فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي PDF

‫الجامعة التقنية الوسىط‬ ‫كلية التقنيات الصحية والطبية‪/‬بغداد‬ ‫قسم تقنيات االشعة‬ ‫فحوصات شعاعية خاصة للجهاز الصفراوي والتناسل‬ ‫المرحلة الثانية‪ /‬الكورس الثان‬ ‫‪1‬‬  ‫الج...

‫الجامعة التقنية الوسىط‬ ‫كلية التقنيات الصحية والطبية‪/‬بغداد‬ ‫قسم تقنيات االشعة‬ ‫فحوصات شعاعية خاصة للجهاز الصفراوي والتناسل‬ ‫المرحلة الثانية‪ /‬الكورس الثان‬ ‫‪1‬‬  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪METHODS OF IMAGING THE HEPATOBILIARY SYSTEM‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية قسم تقنيات االشعة‬ ‫‪2‬‬ Scientific Content: :‫المحتوى العلمي‬ 1. Plain film 2. Ultrasound (US): (a) Transabdominal (b) Endoscopic (c) Intraoperative 3. Computed tomography (CT), including: (a) Routine ‘staging’ (portal venous phase) CT (b) Triple phase ‘characterization’ CT (c) CT cholangiography 4. Magnetic resonance imaging (MRI) 5. Endoscopic retrograde cholangiopancreatography (ERCP) 6. Percutaneous transhepatic cholangiography (PTC) 7. Operative cholangiography 8. Postoperative (T-tube) cholangiography 9. Angiography—diagnostic and interventional 10. Radionuclide imaging: (a) Static, with colloid (b) Dynamic, with iminodiacetic acid derivatives. METHODS OF IMAGING THE PANCREAS 1. Plain abdominal films 2. US: (a) Transabdominal (b) Intraoperative (c) Endoscopic 3. CT 4. MRI 3 5. ERCP 6. Arteriography: (a) Coeliac axis (b) Superior mesenteric artery PLAIN FILMS Not a routine indication.1 May incidentally demonstrate air within the biliary tree or portal venous system, opaque calculi or pancreatic calcification. 4  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪ULTRASOUND OF THE LIVER‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪5‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Suspected focal or diffuse liver lesion 2. Jaundice 3. Abnormal liver function tests 4. Right upper-quadrant pain or mass 5. Hepatomegaly 6. Suspected portal hypertension 7. Staging known extrahepatic malignancy, superseded by CT 8. Pyrexia of unknown origin, now superseded by CT for patients over 30 years old 9. To provide real-time image guidance for the safe placement of needles for biopsy 10. Assessment of portal vein, hepatic artery or hepatic veins 11. Assessment of patients with surgical shunts or transjugular intrahepatic portosystemic shunt (TIPS) procedures 12. Follow-up after surgical resection or liver transplant Contraindications None. Patient Preparation Fasting or restriction to clear fluids only required if the gallbladder is also to be studied. Equipment 3–5-MHz transducer and contact gel. Selection of the appropriate preset protocol and positioning of focal zone will depend upon the type of machine, manufacturer and patient habitus. 6 Technique 1. Patient supine 2. Time-gain compensation set to give uniform reflectivity throughout the right lobe of the liver 3. Suspended inspiration 4. Longitudinal scans from epigastrium or left subcostal region across to right subcostal region. The transducer should be angled cephalad to include the whole of the left and right lobes. 5. Transverse scans, subcostally, to visualize the whole liver 6. If visualization is incomplete, due to a small or high-positioned liver, then additional right intercostal, longitudinal, transverse and oblique scans may be useful. Suspended respiration without deep inspiration may allow useful intercostal scanning. In patients who are unable to hold their breath, real-time scanning during quiet respiration is often adequate. Upright or left lateral decubitus positions are alternatives if visualization is still incomplete 7. Contrast-enhanced ultrasound of the liver uses microbubble agents to enable the contrast enhancement pattern of focal liver lesions, analogous to contrast-enhanced CT or MRI, to be assessed and thus to characterize them. It requires specific software on the ultrasound machine. The lesion to be interrogated is identified on conventional B mode scanning, and then the scanner is switched to low mechanical index (to avoid bursting the bubbles too quickly) contrast-specific scanning mode, with a split screen to allow the contrast-enhanced image to be simultaneously viewed with the B mode image. The images are recorded after bolus injection of the contrast agent flushed with saline. Advantages: Feasible even in the presence of impaired renal function Disadvantages: Limited to single lesion visualization per pass 7 Additional Views Hepatic veins These are best seen using a transverse intercostal or epigastric approach. During inspiration, in real time, these can be seen traversing the liver to enter the inferior vena cava (IVC). Hepatic vein walls do not have increased reflectivity in comparison to normal liver parenchyma. The normal hepatic vein waveform on Doppler is triphasic, reflecting right atrial pressures. Power Doppler may be useful to examine flow within the hepatic segment of the IVC since it is angle-independent. Portal vein The longitudinal view of the portal vein is shown by an oblique subcostal or intercostal approach. Portal vein walls are of increased reflectivity in comparison to parenchyma. The normal portal vein blood flow is toward the liver. There is usually continuous flow, but the velocity may vary with respiration. Hepatic artery This may be traced from the coeliac axis, which is recognized by the ‘seagull’ appearance of the origins of the common hepatic artery and splenic artery. There is normally forward flow throughout systole and diastole, with a sharp systolic peak. 8 Common bile duct Spleen The spleen size should be measured in all cases of suspected liver disease or portal hypertension. Ninety-five percent of normal adult spleens measure 12 cm or less in length, and less than 7 × 5 cm in thickness. The spleen size is commonly assessed by ‘eyeballing’ and measurement of the longest diameter.1 In children, splenomegaly should be suspected if the spleen is more than 1.25 times the length of the adjacent kidney; normal ranges have also been tabulated according to age and sex. ULTRASOUND OF THE GALLBLADDER AND BILIARY SYSTEM Indications 1. Suspected gallstones 2. Right upper quadrant pain 3. Jaundice 4. Fever of unknown origin 5. Acute pancreatitis 6. To assess gallbladder function 7. Guided percutaneous procedures Contraindications None. Patient Preparation Fasting for at least 6 h, preferably overnight. Water is permitted. Equipment 3–5-MHz transducer and contact gel. Selection of the appropriate preset protocol and positioning of focal zone will depend upon the type of machine, manufacturer and patient habitus. A stand off may be used for a very anterior-sited gallbladder. 9 Technique 1. The patient is supine. 2. The gallbladder can be located by following the reflective main lobar fissure from the right portal vein to the gallbladder fossa. 3. Developmental anomalies are rare, but the gallbladder may be intrahepatic or on a long mesentery. In the absence of a previous cholecystectomy, the commonest cause for a nonvisualized gallbladder is when a gallbladder packed with stones is mistaken for a gas-filled bowel (usually duodenal) loop. 4. The gallbladder is scanned slowly along its long axis and transversely from the fundus to the neck, leading to the cystic duct. 5. The gallbladder should then be rescanned in the left lateral decubitus or erect positions, because stones may be missed if only supine scanning is performed. 6. Visualization of the neck and cystic ducts may be improved by head-down tilt. Note: The normal gallbladder wall is never more than 3-mm thick. Additional Views Assessment of gallbladder function 1. Fasting gallbladder volume may be assessed by measuring longitudinal, transverse and antero-posterior (AP) diameters. 2. Normal gallbladder contraction reduces the volume by more than 25%, 30 min after a standard fatty meal. Somatostatin, calcitonin, indomethacin and nifedipine antagonize this contraction. Intrahepatic bile ducts 1. Left lobe—Transverse epigastric scan 2. Right lobe—Subcostal or intercostal longitudinal oblique normal intrahepatic ducts are visualized with modern scanners. Intrahepatic ducts are dilated if their diameter is more than 40% of the accompanying portal vein branch. There is 10 normally acoustic enhancement posterior to dilated ducts but not portal veins. Dilated ducts have a beaded branching appearance. Extrahepatic bile ducts 1. The patient is supine or in a lateral position. 2. The upper common duct is demonstrated on a longitudinal oblique, subcostal or intercostal scan running anterior to the portal vein. The right hepatic artery is often seen crossing transversely between the two. 3. The common duct may be followed downward along its length through the head of the pancreas to the ampulla, and when visualized, transverse scans should also be performed to improve detection of intraduct stones. However, gas in the duodenum often impedes the view of the lower duct. The segment of bile duct proximal to the junction with the cystic duct (the common hepatic duct) is 4 mm or less in a normal adult; 5 mm is borderline and 6 mm is considered dilated. The lower bile duct (common bile duct) is normally 6 mm or less. Distinction of the common hepatic duct from the common bile duct depends on identification of the junction with the cystic duct. This is usually not possible with US. Colour-flow Doppler enables quick distinction of bile duct from ectatic hepatic artery. In less than one-fifth of patients, the artery lies anterior to the bile duct. Postcholecystectomy There is disagreement as to whether the normal common duct dilates after cholecystectomy. Symptomatic patients and those with abnormal liver function tests should have further investigations if the common duct measures more than 4 mm age 40, plus 1 mm for each decade over 40, and 1 mm for the postcholecystectomy state. 11 ULTRASOUND OF THE PANCREAS Indications 1. Suspected pancreatic tumour 2. Pancreatitis or its complications 3. Epigastric mass 4. Epigastric pain 5. Jaundice 6. To facilitate guided biopsy and/or drainage Contraindications None. Patient Preparation Nil by mouth, preferably overnight. Equipment 3–5-MHz transducer and contact gel. Selection of the appropriate preset protocol and positioning of focal zone will depend upon the type of machine, manufacturer and patient habitus. A stand off may be required in thin patients. Technique 1. The patient is supine. 2. The body of the pancreas is located anterior to the splenic vein in a transverse epigastric scan. 3. The transducer is angled transversely and obliquely to visualize the head and tail. 4. The tail may be demonstrated from a left intercostal view using the spleen as an acoustic window. 5. Longitudinal epigastric scans may be useful. 6. The pancreatic parenchyma increases in reflectivity with age, being equal to liver reflectivity in young adults. 12 7. Gastric or colonic gas may prevent complete visualization. This may be overcome by left and right oblique decubitus scans or by scanning with the patient erect. Water may be drunk to improve the window through the stomach, and the scans repeated in all positions. One cup is usually sufficient. Degassed water is preferable. The pancreatic duct should not measure more than 3 mm in the head or 2 mm in the body. Endoscopic US and intraoperative US are useful adjuncts to transabdominal US. EUS may be used to further characterize and biopsy pancreatic solid and cystic lesions. Intraoperative US is used to localize small lesions (e.g. islet cell tumours prior to resection). 13  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪COMPUTED TOMOGRAPHY OF THE LIVER AND BILIARY TREE‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪14‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Suspected focal or diffuse liver lesion 2. Staging known primary or secondary malignancy 3. Abnormal liver-function tests 4. Right upper-quadrant pain or mass 5. Hepatomegaly 6. Suspected portal hypertension 7. Characterization of liver lesion 8. Pyrexia of unknown origin 9. To facilitate the placement of needles for biopsy 10. Assessment of portal vein, hepatic artery or hepatic veins 11. Assessment of patients with surgical shunts or transjugular intrahepatic portosystemic shunt (TIPS) procedures 12. Follow-up after surgical resection or liver transplant Contraindications 1. Pregnancy 2. Allergy to iodinated contrast agents Technique Single-phase (portal phase) contrast-enhancedcomputed tomography This is the technique for the majority of routine liver CT imaging. The liver is imaged during the peak of parenchymal enhancement-i.e. when contrast-medium- laden portal venous blood has fully perfused the liver (around 60–70 s after the start of a bolus injection). Oral contrast may be given but is not necessary if only the liver is being investigated. Slice thickness will depend upon the CT scanner specification but should be 5 mm or less. 15 Multiphasic contrast-enhanced computed tomography The fast imaging times of helical/multislice CT enable the liver to be scanned multiple times after a single bolus injection of contrast medium. Most primary liver tumours receive their blood supply from the hepatic artery, unlike normal hepatic parenchyma, which receives 80% of its blood supply from the portal vein. Liver tumours (particularly hypervascular tumours) will therefore enhance strongly during the arterial phase (beginning 20–25 s after the start of a bolus injection) but are of similar or lower density to enhanced normal parenchyma during the portal venous phase (washout). Some tumours are most conspicuous during early-phase arterial scanning (25 s after the start of a bolus injection), and others later, during the late arterial phase 35 s after the start of a bolus injection. Thus a patient who is likely to have hypervascular primary or secondary liver tumours should have an arterial phase scan as well as a portal venous phase CT scan (discussed previously). Early and late arterial phase with portal venous phase is appropriate for patients with suspected hepatocellular cancer (triple phase). In general, late arterial and portal venous scans are appropriate to investigate suspected hypervascular metastases. Some centres, however, also use a ‘delayed’ or ‘equilibrium’ phase scan at 180 s to help identify and characterize primary liver tumours (quadruple phase). Terminology may be potentially confusing, as some centres may consider a triple phase scan to include arterial, portal and delayed scans. Noncontrast examinations have limited usefulness. Haemangiomas often show a characteristic peripheral discontinuous nodular enhancement and progressive centripetal ‘fill-in’. After the initial dual- or triple- phase protocol, delayed images at 5 and 10 min are obtained through the lesion. 16 COMPUTED TOMOGRAPHIC CHLANGIOGRAPHY Magnetic resonance (MR) cholangiography is noninvasive but sometimes fails to display the normal intrahepatic ducts. Multidetector CT cholangiography can be useful in this instance. With this technique, the biliary tree is opacified using an intravenous (i.v.) cholangiographic agent. Isotropic data from 0.625 mm section thickness slices can be reconstructed to provide high-resolution three-dimensional images. Insufficient opacification may be seen with excessively dilated ducts. Contraindications Allergy to iodinated contrast agents. Indications 1. Screening for cholelithiasis 2. Preoperative screening of anatomy 3. Suspected traumatic bile-duct injury 4. Other biliary abnormalities—e.g. cholesterol polyps, adenomyomatosis and congenital abnormalities Technique 1. Patient fasted for at least 6 h. 2. 100 mL i.v. cholangiographic agent—e.g. meglumine iotroxate (biliscopin R) infused for 50 min as a biliary contrast or iodipamide meglumine 52%—20 mL diluted with 80 mL of normal saline infused over 30 min. 3. CT scan should be obtained at least 35 min after infusion of contrast agent. COMPUTED TOMOGRAPHY OF THE PANCREAS Indications 1. Epigastric pain 2. Obstructive jaundice 3. Suspected pancreatic malignancy 4. Acute pancreatitis and its complications 17 5. Chronic pancreatitis and its complications Contraindications 1. Pregnancy 2. Allergy to iodinated contrast agents Technique 1. Negative (e.g. water) oral contrast is generally preferred. Positive (e.g. iodinated) contrast may be given if necessary to opacify distal bowel loops but is contraindicated if CT angiography is to be performed. Volume and timing of oral contrast agent will depend upon whether opacification of distal bowel loops is required. 2. Venous access is obtained. 3. The patient is scanned supine and a scout view is obtained. 4. An initial non-contrast-enhanced examination to identify calcification is no longer indicated, as this will be evident on vascular phases. 5. The volume and strength of the i.v. contrast will depend upon the speed of the scanner. The volume of i.v. contrast usually varies from 100 to 150 mL s−1 of iodinated contrast at 3–4 mL s−1, with a saline chaser, depending on the scanner type. Pancreatic parenchymal phase enhancement (35–40 s after commencement of bolus injection) is necessary for optimum contrast differentiation between pancreatic adenocarcinoma and normal pancreatic tissue, with portal venous phase scans (65– 70 s after onset of the injection) included in the protocol to investigate hepatic metastatic disease. Images should be reconstructed at 0.625–1.25 mm in the pancreatic phase and 2 mm in the portal venous phase. 6. Islet cell tumours and their metastases may show avid enhancement on arterial phase scans and become isodense with normal pancreatic tissue on portal phase scans. A portal phase scan is generally necessary to investigate flow and the relationship of the tumour to the portal vein. 18  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪MAGNETIC RESONANCE IMAGING OF THE LIVER‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪19‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Lesion characterization following detection by CT or US. Unenhanced MRI including heavily T2 weighted sequences and DWI can be considered the definitive protocol for detection and characterization of typical cystic and cystic like structures and haemangiomas. 2. Lesion detection, particularly prior to hepatic resection for hepatic metastatic disease. Magnetic resonance imaging (MRI) is rapidly emerging as the imaging modality of choice for detection and characterization of liver lesions. There is high specificity with optimal lesion-to-liver contrast and characteristic appearances on differing sequences and after contrast agents. Focal lesions may be identified on most pulse sequences. Most metastases are hypo- to isointense on T1 and iso- to hyperintense on T2-weighted images. However, multiple sequences are usually necessary for confident tissue characterization. The timing, degree and nature of tumour vascularity form the basis for liver lesion characterization based on enhancement properties. Liver metastases may be hypo- or hypervascular. Magnetic Resonance Imaging Pulse Sequences A minimum field strength of 1.5T is required using a multichannel phased-array coil. Common pulse sequences are: 1. T1-weighted spoiled gradient echo (GRE). This has replaced the conventional spin-echo sequence. In and out of phase scans are used to investigate patients with suspected fatty liver. 2. Magnetization-prepared T1-weighted GRE. A further breath-hold technique with very short sequential image acquisition. 3. T1-W GRE fat-suppressed volume acquisition. This sequence can be obtained rapidly following i.v. gadolinium. 20 4. T2-weighted spin echo (SE). T2-weighted fast spin-echo (FSE; General Electric) or turbo spin-echo (TSE; Siemens). Compared with conventional T2-weighted SE images, FSE/TSE images show: 1. Fat with higher signal intensity. 2. Reduced magnetic susceptibility effects which are of advantage in patients with embolization coils, IVC filters, etc., but disadvantageous after injection of superparamagnetic oxide contrast agent. 3. Increased magnetization transfer which may lower signal intensity for solid liver tumours. These sequences may be obtained with fat suppression. Fat suppression: 1. Decreases the motion artifact from subcutaneous and intraabdominal fat 2. Increases the dynamic range of the image 3. Improves signal-to-noise and contrast-to-noise ratios of focal liver lesions Very heavily T2-weighted sequences can be used to show water content in bile ducts, cysts and some focal lesions. These may be obtained as: 1. Gradient echo breath-hold sequences (e.g. fast imaging with steady-state precession (FISP), fast imaging employing steady state acquisition [FIESTA]) 2. Breath-hold very fast spin echo (e.g. half Fourier acquisition singleshot turbo spin echo [HASTE]) 3. Non-breath-hold respiratory-gated sequences used for magnetic resonance cholangiopancreatography (MRCP) Fat suppression is also used to allow better delineation of fluidcontaining structures. Short tau inversion recovery (STIR) also suppresses fat, which has a short T1 relaxation time. Other tissues with short T1 relaxation (haemorrhage, metastases and melanoma) are also suppressed. 21 Diffusion Weighted Imaging This very rapidly acquired sequence forms an image based on the microscopic motion of water molecules and provides additional information regarding both lesion detection and characterization. Contrast-enhanced Magnetic Resonance Liver Imaging Gadolinium-enhanced T1-weighted magnetic resonance imaging This probably does not increase sensitivity for focal abnormalities, but may help in tissue characterization. When used in conjunction with spoiled GRE sequences, it is possible to obtain images during the arterial phase (ideal for metastatic disease and hepatocellular carcinoma), portal phase (hypovascular malignancies) and equilibrium phase (cholangiocarcinoma, slow-flow haemangiomas and fibrosis). Hepatic arterial phase and FSE T2-weighted sequences are the most sensitive sequences for the detection of hepatic metastases of neuroendocrine tumours. Contrast should be administered at a rate of 1–2 mL s−1 followed by a 20 mL saline flush at 1–2 mL s−1 using a power injector. Bolus triggered techniques are recommended for optimized arterial phase. Liver-specific contrast agents Standard gadolinium extracellular agents are commonly used for liver MRI as described previously, but other contrast agents have been developed to enhance the distinction between normal liver and lesions, especially malignant lesions. These are mostly used in patients who are potentially suitable for major liver surgery, e.g. resection or transplantation: 1. Hepato-biliary agents (e.g. Gadoxetic acid [Primovist]; gadobenate dimeglumine [Multihance]) are taken up by normal hepatocytes and excreted by normal liver into the bile. Liver specific contrast agents shorten T1 relaxation times, which results in normal liver showing increased signal on T1 weighted sequences. Metastases, and other lesions not containing normal-functioning hepatocytes, show 22 as a lower signal than the background liver. Lesions containing hepatocytes will enhance to varying extents. High signal contrast can be seen in the bile ducts, which has clinical usefulness. These agents are also excreted by the kidneys. Further details can be found in 2. Reticuloendothelial (RE) cell agents (also called super paramagnetic iron oxides, SPIO) are not currently available, as they have been withdrawn from the market for commercial reasons. They are taken up by the RE or Kuppfer cells in normal liver, giving a decrease in signal on T2- and especially T2*- weighted sequences. They can also be used with T1-weighted sequences for characterization. On T2*-weighted images, malignant lesions without RE cells show as higher signal than the background normal liver. Examination with a SPIO agent may be combined with dynamic gadolinium enhancement in order to maximize the detection and characterization of metastases (and benign lesions) in a patient being considered for surgical resection of metastases. The same combination can be used in a patient with cirrhosis to maximize diagnosis and characterization of HCC versus dysplastic or regenerative nodules. Magnetic resonance angiography Contrast-enhanced spoiled GRE images may be obtained to give information with respect to the hepatic artery, portal vein and hepatic venous system.MA RESONANCE MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY Magnetic resonance cholangiopancreatography (MRCP) with 3T scanner provides improved image quality over 1.5T scanners. Indications 1. Investigation of obstructive jaundice 2. Suspected biliary colic/bile duct stones 3. Suspected chronic pancreatitis 23 4. Suspected sclerosing cholangitis 5. Investigation of jaundice or cholangitis in patients who have undergone biliary enteric anastomosis 6. Prior to ERCP/PTC Contraindications Those that apply to MRI Technique MRCP is a noninvasive technique, which uses heavily T2-weighted images to demonstrate the intra- and extrahepatic biliary tree and pancreatic duct. Most commonly used to demonstrate the presence of stones and the level and cause of obstruction, especially combined with cross-sectional MRI, in cases of tumour or suspected tumour. MAGNETIC RESONANCE IMAGING OF THE PANCREAS Indications 1. Staging of pancreatic tumours 2. Suspected islet cell tumour 3. Other indications are similar to CT, although CT is generally preferred because of availability, cost and time implications. Technique Sequences are acquired in both axial and coronal oblique planes. The optimal plane depends on the location of the tumour. For pancreatic head tumours, the pancreatic and portal venous phase acquisitions are best acquired initially in an oblique coronal plane followed by axial. The converse is true for tumours of the body and tail: 1.T1-weighted fat-suppressed gradient-echo. Normal pancreas hyperintense to normal liver. 2. T1-weighted spoiled gradient-echo (SPGR, GE Medical Systems; fast low-angle shot [FLASH], Siemens). Normal pancreas isointense to normal liver. 24 3. T2 weighted turbo-spin echo. 4. Gadolinium-enhanced T1-weighted fat-suppressed spoiled GRE. Images are obtained immediately after the injection of contrast medium, after 45 s, after 90 s and after 10 min. Normal pancreas hyperintense to normal liver and adjacent fat on early images, fading on later images. Bolus triggered techniques are recommended for an optimal arterial phase. 5. The polypeptide hormone secretin may be given slowly i.v. over 1 minute to temporarily distend the pancreatic ducts. This can help better assess pancreatic ductal anomalies and also provide information about the exocrine function of the gland. 25  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قس قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪INTRAOPERATIVE CHOLANGIOGRAPHY‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪26‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications Performed during cholecystectomy or bile duct surgery, to avoid need for surgical exploration of the common bile duct. (Preoperative MRCP and/or EUS has replaced this technique in some centres.) Contraindications None. Contrast Medium High osmolar contrast media (HOCM) or low osmolar contrast media (LOCM) 150—i.e. low iodine content to avoid obscuring any calculi; 20 mL. Equipment 1. Operating table with CR/DR available or a film cassette tunnel 2. Mobile x-ray machine Patient Preparation As for surgery. Technique The surgeon cannulates the cystic duct, with a fine catheter prefilled with contrast medium (with all air bubbles that might simulate calculi) carefully excluded. Images 1. After 5 mL have been injected. 2. After 20 mL have been injected. Contrast medium should be seen to flow freely into the duodenum. Spasm of the sphincter of Oddi is a fairly frequent occurrence and may be due to anaesthetic agents or surgical manipulation. It can be relieved by glucagon, propantheline or amyl nitrite. The criteria for a normal operative choledochogram were given by Le Quesne1 as the following: 27 1. Common bile duct width not greater than 12 mm 2. Free flow of contrast medium into the duodenum 3. The terminal narrow segment of the duct is clearly seen 4. There are no filling defects 5. There is no excess retrograde filling of the hepatic ducts. POSTOPERATIVE (T-TUBE) CHOLANGIOGRAPHY Indications 1. To exclude biliary tract calculi, where (a) operative cholangiography was not performed, or (b) the results of operative cholangiography are not satisfactory or are suspect 2. Assessment of biliary leaks following biliary surgery Contraindications None. Contrast Medium HOCM or LOCM 150 mg I mL–1; 20–30 mL. Equipment Fluoroscopy unit with spot image device. Patient Preparation Antibiotics may be considered if previous cholangitis or if immunosuppressed (e.g. liver transplant). Preliminary Image Coned supine PA of the right side of the abdomen. Technique 1. The examination is performed on or about the 10th postoperative day, prior to removal of the T-tube. 28 2. The patient lies supine on the x-ray table. The drainage tube is clamped off near to the patient and cleaned thoroughly with antiseptic. 3. A 23G needle, extension tubing, and 20 mL syringe are assembled and filled with contrast medium (e.g. a butterfly needle). After all air bubbles have been expelled, the needle is inserted into the tubing between the patient and the clamp. The injection is made under fluoroscopic control, the total volume depending on duct filling. In the case of recent biliary anastomosis (i.e. liver transplant), only a small volume of contrast (approximately 10 mL), gently injected, is required. Images Intermittent fluoroscopic ‘grab’ images during filling are frequently useful. PA and oblique exposures when there is satisfactory opacification of the biliary system. Aftercare None. Complications Due to the contrast medium The biliary ducts do absorb contrast medium, and cholangio-venous reflux can occur with high injection pressures. Adverse reactions are therefore possible, but the incidence is small. Due to the technique Injection of contrast medium under high pressure into an obstructed biliary tract can produce septicaemia.CU TANEOUS TRANSHEPATIC PERCUTANEOUS TRANSHEPATIC CHOLANGIOGRAPHY Indications 1. Prior to therapeutic intervention, e.g. biliary drainage procedure to relieve obstructive jaundice, or to drain infected bile 2. Place a percutaneous biliary stent 29 3. Dilate a postoperative stricture 4. Stone removal (discussed later) 5. To facilitate ERCP by rendezvous technique 6. Rarely for diagnostic purposes only Contraindications 1. Bleeding tendency: (a) Platelets less than 100 × 109 L–1 (b) Prothrombin time prolonged >2 s more than control Vitamin K will correct abnormal prothrombin time due to biliary obstruction if hepatocellular function is preserved; if it is not, or the patient requires urgent intervention, then platelet transfusion and FFP can be used. 2. Biliary tract sepsis except specifically to control the infection by drainage. Contrast Medium LOCM 150 mg I mL–1; 20–60 mL. Equipment 1. Fluoroscopy unit with digital spot film device (tilting table optional) 2. Chiba needle (a fine, flexible 22G needle with stilette, 15–20-cm long) 3. Appropriate catheters and wire for drainage or interventional procedure planned Patient Preparation 1. Haemoglobin, prothrombin time and platelets are checked, and corrected if necessary 2. Prophylactic antibiotics, e.g. ciprofloxacin 500–750 mg oral before and after procedure 3. Nil by mouth or clear fluids only for 4 h prior to the procedure 4. Ensure patient well hydrated, by i.v. fluids if necessary 5. Sedation (i.v.) and analgesia with oxygen and monitoring 30 Preliminary Imaging US to confirm position of liver and dilated ducts. Technique 1. The patient lies supine. Using US, a spot is marked over the right or left lobe of the liver as appropriate. On the right side this is usually intercostal between mid and anterior axillary lines. For the left lobe this is usually subcostal to the left side of the xiphisternum in the epigastrium. 2. Using aseptic technique, the skin, deeper tissues and liver capsule are anaesthetized at the site of the mark. 3. During suspended respiration the Chiba needle is inserted into the liver, but once it is within the liver parenchyma, the patient is allowed shallow respirations. The needle is advanced into the liver with real-time US or fluoroscopy control. 4. The stilette is withdrawn and the needle connected to a syringe and extension tubing prefilled with contrast medium. Contrast medium is injected under fluoroscopic control while the needle is slowly withdrawn. If a duct is not entered at the first attempt, the needle tip is withdrawn to approximately 2–3 cm from the liver capsule and further passes are made, directing the needle tip more cranially, caudally, anteriorly or posteriorly, and contrast is injected until a duct is entered. The incidence of complications is not related to the number of passes within the liver itself and the likelihood of success is directly related to the degree of duct dilatation and the number of passes made. 5. Excessive parenchymal injection should be avoided, and when it does occur, it results in opacification of intrahepatic lymphatics. Injection of contrast medium into a vein or artery is followed by rapid dispersion. 6. If the intrahepatic ducts are seen to be dilated, bile should be aspirated and sent for microbiological examination. (The incidence of infected bile is high in such cases.) 31 7. Contrast medium is injected to outline the duct system and allow access for a guidewire or selection of an appropriate duct for drainage. Where undertaken for diagnostic purposes only, PTC, the needle can be removed once suitable images have been obtained. 8. Care should be taken not to overfill an obstructed duct system as this may precipitate septic shock. Images As contrast medium is denser than bile, the sequence of duct opacification is therefore gravity-dependent and determined by the site of injection and the position of the patient. Using the undercouch tube with the patient horizontal: 1. PA 2. LAO 3. RAO 4. If on a nontilting table, rolling the patient onto the left side will fill the left ducts and common duct above an obstruction. When the previous images have shown an obstruction at the level of the porta hepatis, a further image after the patient has been tilted towards the erect position for 30 min may show the level of obstruction to be lower than originally thought. Delayed Images Images taken after several hours, or the next day, may show contrast medium in the gallbladder if this was not achieved during the initial part of the investigation. Aftercare Bed rest, pulse and blood pressure measurement half-hourly for 6 h. Complications Morbidity approximately 3%; mortality less than 0.1%.1 Due to the contrast medium Allergic/idiosyncratic reactions—very uncommon. 32 Due to the technique Local 1. Puncture of extrahepatic structures—usually no serious sequelae 2. Intrathoracic injection 3. Cholangitis 4. Bile leakage—may lead to biliary peritonitis (incidence 0.5%). More likely if the ducts are under pressure and if there are multiple puncture attempts. Less likely if a drainage catheter is left in situ. 5. Subphrenic abscess 6. Haemorrhage 7. Shock—owing to injection into the region of the coeliac plexus Generalized Bacteraemia, septicaemia and endotoxic shock. The likelihood of sepsis is greatest in the presence of choledocholithiasis because of the higher incidence of preexisting infected bile. 33  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪BILIARY DRAINGE‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪34‬‬ Scientific Content: :‫المحتوى العلمي‬ EXTERNAL BILIARY DRAINAGE This is achieved following transhepatic cannulation of the biliary tree as described previously. The procedure may be performed to relieve jaundice or sepsis prior to surgery or as a further percutaneous intervention. INTERNAL BILIARY DRAINAGE This can be achieved following transhepatic (as described previously) or endoscopic cannulation of the biliary tree. A percutaneous drainage catheter may allow internal or external drainage with side holes above and below the point of obstruction. At ERCP an endoprosthesis or stent is placed to drain bile from above a stricture or to prevent obstruction by a stone in the duct. Indications 1. Malignant biliary stricture 2. Benign stricture following balloon dilatation Contraindications As for PTC. Contrast Media LOCM 200 mg I mL−1; 20–60 mL. Equipment 1. Wide-channelled endoscope for introduction of endoprosthesis by ERCP 2. A biplane fluoroscope facility is useful but not essential for transhepatic puncture 3. Set including guidewires, dilators and endoprosthesis Patient Preparation 35 Technique Transhepatic 1. A percutaneous transhepatic cholangiogram is performed. 2. A duct in the right lobe of the liver that has a horizontal or caudal course to the porta hepatis is usually chosen. This duct is studied on US to judge its depth, and then a 22G Chiba needle is inserted into the duct under US or fluoroscopic guidance. A coaxial introducer system is used over a 0.018 guidewire to allow 0.035 wire and catheter access into the bile ducts. If the duct is not successfully punctured, the Chiba needle is withdrawn but remains within the liver capsule, allowing a further puncture attempt. Once a 0.035 wire is established in the bile duct, a sheath can be inserted— e.g. 7-F. Bile can be drained through the side arm of the sheath while a catheter is manipulated over the wire. For internal drainage or stent insertion, the wire and catheter must be passed through the stricture into the duodenum or postoperative jejunal loop. For external drainage, a suitable catheter can be inserted over the wire after the sheath is withdrawn. A variety of wires and catheters may be needed to cross difficult strictures. Failing this, external drainage is instituted, and a further attempt is made to pass the stricture a few days later. 3. An internal/external catheter may be placed across the stricture and secured to the skin with sutures. 4. A metal biliary stent may be positioned and deployed across a malignant stricture to facilitate internal drainage of bile. Balloon dilatation may be required before or after stent deployment in some cases. A temporary external drainage tube may be left in place for 24–48 h. Endoscopic 1. Cholangiography following cannulation of the biliary tree 2. Endoscopic sphincterotomy 3. A guidewire is placed via the channel of the endoscope through the sphincter and pushed past the stricture using fluoroscopy to monitor progress 36 4. Following dilatation of the stricture, the endoprosthesis (plastic stent) is pushed over the guidewire and sited with its side-holes above and below the stricture. Metal biliary stents can also be placed at ERCP when appropriate. Aftercare 1. As for percutaneous transhepatic cholangiography 2. Antibiotics for at least 3 days 3. An externally draining catheter should be regularly flushed through with normal saline and exchanged at 3-monthly intervals. (It is rare to leave a drain in situ for such a long period.) Complications 1. As for PTC, ERCP and sphincterotomy 2. Sepsis—particularly common with long-term, externally draining catheters 3. Dislodgement of catheters, endoprostheses 4. Blockage of catheters/endoprostheses 5. Perforation of bile duct above the stricture on the passage of giudewire PERCUTANEOUS EXTRACTION OF RETAINED BILIARY CALCULI (BURHENNE TECHNIQUE) Indications Retained biliary calculi seen on the T-tube cholangiogram (incidence3%). Contraindications 1. Small T-tube (98% compared with 60% for plain films). Technique As for preliminary films for excretion urography (discussed later). INTRAVENOUS EXCRETION UROGRAPHY The technique is less frequently used than in the past and has now been very largely replaced by US, CT or MRI or a combination. Indications 1. Haematuria 2. Renal colic (see the section on variation) 3. Recurrent urinary tract infection 4. Loin pain 5. Suspected urinary tract pathology Contraindications General contraindications to intravenous (i.v.) watersoluble contrast media and ionizing radiation. In patients with contrast medium allergies, alternative modalities such as ultrasound or MR can be considered. Patients with impaired 42 renal function, particularly those with diabetes, should be prepared with oral or i.v. hydration, or an alternative imaging modality should be considered. Contrast Medium Low osmolar contrast material (LOCM) 300–370 mg I mL−1 Adult dose 50–100 mL Paediatric dose 1 mL kg−1 Patient Preparation 1. No food for 5 h prior to the examination. Dehydration is not necessary and does not improve image quality. 2. The routine administration of bowel preparation has been shown not to improve the diagnostic quality of the examination. Preliminary Images Supine, full-length anterior posterior (AP) of the abdomen, in inspiration. The lower border of the cassette is at the level of the symphysis pubis, and the x-ray beam is centred in the midline at the level of the iliac crests. If necessary, the location of overlying opacities may be further determined by: supine AP film of the renal areas, in expiration. The x-ray beam is centred in the midline at the level of the lower costal margin. 35° posterior oblique views (side of interest towards the film) tomography of the kidneys The examination should not proceed further until these images have been reviewed by the radiologist or radiographer and deemed satisfactory. Technique Venous access is established. The gauge of the cannula/needle should allow the injection to be given rapidly as a bolus to maximize the density of the nephrogram. 43 Images 1. Immediate film. AP of the renal areas. This film is exposed 10–14 s after the injection (approximate ‘arm-to-kidney’ time). It aims to show the nephrogram at its most dense—i.e. the renal parenchyma opacified by contrast medium in the renal tubules. Tomography may assist in evaluation of the renal outline or possible masses (or ultrasound if subsequently available). 2. 5-min film. AP of the renal areas. This film gives an initial assessment of pathology—specifically the presence or absence of obstruction before administering compression. A compression band is then applied positioned midway between the anterior superior iliac spines—i.e. over the ureters as they cross the pelvic brim. The aim is to produce pelvicalyceal distension. Compression is, however, contraindicated: (a) after recent abdominal surgery (b) after renal trauma (c) if there is a large abdominal mass or aortic aneurysm (d) when the 5-min film shows already distended calyces indicative of obstruction 3. 10-min film. AP of the renal areas. There is usually adequate distension of the pelvicalyceal systems with opaque urine by this time. Compression is released when satisfactory demonstration of the pelvicalyceal system has been achieved. If the compression film is inadequate, the compression should be checked and repositioned if necessary and a further 50 mL of contrast medium administered and a repeat film taken after 5 min. 4. Release film. Supine AP abdomen taken immediately after the release of compression. This film is taken to show the ureters. If this film is satisfactory, the patient is asked to empty the bladder. 5. After micturition film. Full-length supine AP abdomen. The aims of this film are to assess bladder emptying, to demonstrate drainage of the upper tracts, to aid the 44 diagnosis of bladder tumours, to confirm ureterovesical junction calculi, and uncommonly, to demonstrate a urethral diverticulum in females. Additional Images 1. 35° posterior oblique of the kidneys, ureters or bladder—for equivocal collecting system lesions or localization of calculi 2. Tomography—if renal outlines are not well seen 3. Prone abdomen following the release film—may improve visualization of distal ureters 4. Delayed films at increasing (doubling of time intervals) up to 24 h after injection in renal obstruction Variation Renal colic—a limited study may be performed: preliminary films; 20-min full length (no compression); postmicturition full length; delayed films up to 24 h as required to show level and cause of obstruction. ULTRASOUND OF THE URINARY TRACT Indications 1. Renal mass lesion 2. Renal parenchymal disease 3. Renal obstruction/loin pain 4. Haematuria 5. Hypertension 6. Renal cystic disease 7. Renal size measurement 8. Bladder outflow obstruction 9. Urinary tract infection 10. Bladder tumour 11. Following renal transplant: 45 (a) Obstruction (b) Patency of vessels (c) Perirenal collections. 12. To guide needle placement in interventional procedures 13. Renal vascular studies. Contraindications None. Patient Preparation Kidneys only—none. Kidneys and bladder—prehydrate with oral fluids, e.g. 500–1000 mL 1 h before scan; patient attends with a full bladder. This may have the disadvantage of making the collecting systems appear mildly hydronephrotic premicturition. Equipment 3.5–5-MHz transducer. Technique 1. Patient supine, right (RAO) and left anterior oblique (LAO) positions or lateral for kidneys. The kidneys are scanned longitudinally in an oblique coronal plane supplemented by transverse sections perpendicular to the axis. The right kidney may be scanned through the liver and posteriorly in the right loin. The left kidney is harder to visualize anteriorly, but can be visualized from a lateral approach. In difficult cases, the patient should lie on their side with a pillow under the loin to widen the space between the rib cage and pelvis. 2. The length of the kidney measured by US is 1–2 cm smaller than that measured at excretion urography, because there is no geometric magnification. With US measurement, care must be taken to ensure that the true longitudinal length measurement is obtained. The range of lengths of the normal kidneys is 9–12 cm, and the difference between each kidney should be less than 1–2 cm. 46 3. The bladder is scanned suprapubically in transverse and longitudinal planes. Measurements taken of the three orthogonal diameters before and after micturition enable an approximate volume to be calculated by multiplying the three diameters and applying a conversion factor. (A conversion factor [approximately 0.5] is usually preprogrammed into modern ultrasound machines.) 4. Renal transplants are usually located in the right or left iliac fossa. These lie fairly superficially and are easy to evaluate using oblique planes and gentle pressure to displace overlying bowel loops. 5. The native or transplant kidneys can be evaluated for vascular pathology using Doppler techniques. Renal artery stenosis is diagnosed by direct Doppler interrogation of the main renal arteries from a transabdominal approach. Elevated peak systolic velocities >200 cm s−1 are suggestive of a >50% stenosis. Alternatively, as the main renal arteries in the native kidneys are often hard to visualize, the intrarenal arteries can be evaluated from a flank approach for downstream changes in waveform—the tardus parvus pattern, a slow rise (tardus) to a reduced peak (parvus), producing a prolonged acceleration time (a value >70 ms is indicative of a severe stenosis). Renal vein thrombosis is diagnosed by absent colour Doppler venous flow, direct visualization of thrombus within the distended vein, and a raised resistive index with reversal of arterial diastolic flow within the intrarenal arteries. 47  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪COMPUTED TOMOGRAPHY URINARY TRACT‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪48‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Renal colic/renal stone disease 2. Renal tumour 3. Renal/perirenal collection 4. Loin mass 5. Staging and follow-up of renal, collecting system or prostatic cancer (local staging of prostatic cancer is performed using thin-section MRI) 6. Investigation of renal tract obstruction 7. CT angiography may be used to assess renal vessels for suspected renal artery stenosis or arteriovenous fistula or malformation. Techniques Standard diagnostic computed tomography This technique is used to stage and follow-up known renal-tract malignancy or to investigate nonspecific signs attributed to the renal tract. Examination of the thorax in addition to the abdomen and pelvis is usually performed, where pulmonary metastatic disease or mediastinal nodal spread is a possibility: 1. Venous access is obtained. 2. Patient lies supine. 3. Scanogram is taken of chest, abdomen and pelvis as appropriate. 4. 100 mL i.v. LOCM given. 5. Scans obtained approximately 70 s (portal venous phase) after i.v. contrast (arterial phase scans of the liver may be appropriate in those patients with suspected metastatic renal cancer who may have hypervascular liver metastases). Renal lesion characterization computed tomography this is used to assess renal cysts or masses identified on another imaging modality such as ultrasound. Pre- and post-i.v. contrast scans are obtained through the kidneys in order to assess precontrast attenuation and 49 subsequent enhancement patterns. Many practitioners advise the postcontrast scan be performed at 100 s (nephrographic phase) to prevent small intraparenchymal lesions being obscured by corticomedullary differentiation. Adrenal lesion characterization computed tomography Indication: Adrenal mass is suspected or needs characterization. Technique: Unenhanced CT of the abdomen to enable measurement of attenuation (HU) of any adrenal mass. A value less than 10 HU is highly specific for a benign (lipid-rich) adenoma, and is often the only test required. This may, however, be supplemented when necessary by washout CT, remeasurement of the adrenal density in Hounsfield units at 15 min following i.v. contrast. Benign adenomas (whether or not lipid-rich) typically show rapid washout of contrast; an absolute percentage washout (APW) greater than 60% or relative percentage washout (RPW) greater than 40%, on delayed images, is highly specific for a benign lesion. Computed tomography kidneys, ureters, bladder Plain CT (commonly referred to as CT KUB—kidneys, ureters, bladder) is useful to assess possible stone disease. It is now used in most centres as the primary investigation of renal colic (replacing plain KUB radiograph): 1. No i.v. or oral contrast is given. 2. Patient supine. (Some authorities advise prone scanning to differentiate if stones are impacted at the vesicoureteric junction or have passed into the bladder.) 3. A low-radiation-dose technique is used to scan from the top of the kidneys to include the bladder base with a slice thickness of 5 mm or less, as determined by CT scanner. (Due to the low-dose nature of the scan and the absence of i.v. and oral contrast, the scan has a very limited role in identifying pathology other than renal tract calculus disease and should not be used indiscriminately for investigation of non-specific abdominal pain.) 50 Computed tomography urogram (CTU) This technique uses a combination of unenhanced, nephrographic and delayed scans following i.v. contrast to sequentially allow examination of renal parenchyma and collecting systems. Suggested protocol includes the following: 1. An oral water load of 500–1000 mL 45–60 min before injection is recommended to ensure a diuresis and collecting system dilatation. No positive oral contrast is given. 2. Patient supine 3. Initial low-dose unenhanced scans of urinary tract (CT KUB) to determine if renal tract calculus disease is present 4. LOCM 300 mg I mL−1 100 mL is given as bolus intravenously. 5. Thin-section (usually 1 mm) scans are obtained from the diaphragm to lower poles of kidneys during the nephrographic/ parenchymal enhancement phase (100 s following start of bolus injection). Alternatively, the scan may instead be acquired during the portal venous phase (70 s), but normal corticomedullary differentiation may make small tumours difficult to appreciate. 6. Delayed thin-section (1 mm) scans are acquired from upper pole of kidneys to bladder base 20 min after contrast injection, to examine collecting systems and ureters. 7. Source images are reviewed along with multiplanar reconstructions. Postprocessing with maximum-intensity projections and surfaceshaded displays may be helpful, especially for demonstration. Variations 51 The nephrographic phase may be omitted if the scan is specifically for urothelial tumour or collecting system assessment. Some protocols use diuretics or abdominal compression bands to achieve collecting system distension. Radiation dose is a significant consideration for a triple-phase CTU (compared with an IVU), but newer iterative reconstruction techniques increasingly available are reducing this. Some authorities advocate the use of a split bolus technique, i.e. 50 mL of i.v. contrast 10– 15 min before scanning, with a further 50 mL at the time of the scan, to achieve demonstration of the nephrographic and pyelographic phases in the same acquisition with consequent radiation dose saving. Computed tomography angiography Angiography principles. Indications 1. Renal artery stenosis 2. Renal artery aneurysm, arteriovenous malformation, dissection or thrombosis 3. Delineation of vascular anatomy prior to laparoscopic surgery, e.g. nephrectomy, pyeloplasty Technique 1. No oral iodinated contrast used. 2. Scan from the upper pole of the kidneys to the aortic bifurcation. Modern scanners are fast enough to produce high quality studies of the whole abdomen. 3. Narrow collimation (1 mm). 4. 100–150 mL i.v. contrast medium (LOCM 300) injected at 3–4 Ml s−1. 5. Use of bolus tracking/triggering devices or timing test injections is recommended to ensure appropriate timing. Otherwise scans are initiated after a preset empiric delay of 20–25 s from start of contrast material injection. 52 6. Source axial scans are supplemented by multiplanar reconstructions and maximum intensity projection, and volume-rendered surface shaded display postprocessing. 53  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪MAGNETIC RESONANCE URINARY TRACT‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪54‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Local staging of prostatic cancer 2. Local staging of bladder cancer 3. Staging of pelvic lymph nodes 4. Renal mass 5. Screening of patients with von Hippel–Lindau disease or their relatives, or other genetic conditions 6. MR urography where i.v. or CT urography contraindicated 7. MR angiography: potential living related donors, suspected renal artery stenosis Technique Technique will be tailored to the clinical indication. MR of the kidneys and upper abdomen will generally include T1 and T2 weighted sequences in axial and coronal planes with or without fat saturation; with pre- and postcontrast T1 weighted imaging at 30 and 70 s. MRI of the abdomen and pelvis can be obtained to assess retroperitoneal lymphadenopathy as part of the staging investigations for patients with bladder and prostate cancer, but CT is often used for this purpose with MRI reserved for local staging. MAGNETIC RESONANCE IMAGING OF THE PROSTATE Technique/Example Protocol 1. Patient supine. Phased array body coil. The best images will be obtained with an endorectal coil, but many authorities do not use these. 1.5T or 3T scanners are both used. 3T scanners afford better signal-to-noise ratio, but may be subject to more artifacts—notably susceptibility. 2. Antiperistaltic drugs (hyoscine butyl-bromide or glucagon are recommended) 3. T1W and T2W axial scans whole pelvis 55 4. Thin-section (3–4 mm) small field of view T1-weighted spin echo (SE) scans in axial plane orthogonal to the axis of the prostate to evaluate for postbiopsy haemorrhage 5. Thin-section (3–4 mm) small field of view T2-weighted SE scans in transverse, sagittal and coronal planes orthogonal to the axis of the prostate 6. Multiparametric MRI—there is increasing use of the following functional studies: (a) Diffusion weighted imaging b values 0, 100 and 800–1400 Sn mm−2 with apparent diffusion coefficient (ADC) map (b) Dynamic contrast-enhanced (DCE) T1W imaging (c) MR spectroscopy—citrate, creatine, choline MAGNETIC RESONANCE UROGRAPHY Indications 1. To demonstrate the collecting system/determine level of obstruction in a poorly functioning/obstructed kidney 2. Urinary tract obstruction unrelated to urolithiasis. Suspected renal colic from underlying calculus is better imaged with CT KUB. 3. Congenital anomalies 4. Renal transplant donor assessment (combined with MR angiography) Technique The two most common MR urographic techniques are: static fluid-sensitive urography using heavily T2-weighted MRI techniques to visualize fluid-filled structures (equivalent to magnetic resonance cholangio- pancreatography [MRCP]) excretory MR urography using T1-weighted sequences post gadolinium enhancement 1. Patient supine with an empty bladder for comfort. If the bladder is of interest, a moderately full bladder may be preferred. 56 2. Scout views are obtained. 3. Static MR urography may be performed prior to excretory urography. Thick-slab, single-shot, fast-spin echo or a similar thin-section technique, e.g. half-Fourier rapid acquisition with relaxation enhancement; single-shot, fast-spin echo; singleshot, turbo-spin echo. 3D respiratory triggered sequences may be used to obtain thin- section data sets that may be further postprocessed. 4. Oral or i.v. hydration, compression or diuretics may be used to enhance collecting system distension. 5. Excretory MR urography: a gadolinium-based contrast agent is administered i.v. using a dose of 0.1 mmol gadolinium kg−1 body weight. The collecting systems are imaged during the excretory phase (10–20 min) using a breath-hold, 3D gradient echo, T1-weighted sequence. Fat suppression will improve the conspicuity of the ureters. T2* effects from a high concentration of contrast agent may reduce the signal intensity of urine and potentially obscure small masses within the collecting system. This can be overcome by using a lower volume of i.v. contrast but may compromise soft-tissue imaging.IC RESONANCE IMAGING OF THE MAGNETIC RESONANCE IMAGING OF ADRENALS Indications Characterization of adrenal mass. Technique Chemical shift imaging: based on a high proportion of intracellular lipid causing alteration of the local magnetic environment within the voxel and hence resonant frequency of protons. Lipid-rich benign adenomas can be shown to lose signal on opposed phase T1W imaging compared with in-phase studies. This is highly specific. Alternatively, unenhanced CT can be used to characterize an adrenal mass as malignant, or 18-F fluorodeoxyglucose positron emission tomography (18-F FDG-PET) can be used to characterize an adrenal mass as malignant. 57  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪MICTURATING CYSTOURETHROGRAPHY‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪58‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Vesicoureteric reflux 2. Study of the urethra during micturition 3. Bladder leak post surgery or trauma 4. Urodynamic studies, e.g. for incontinence Contraindications Acute urinary tract infection. Contrast Medium High osmolar contrast material (HOCM) or LOCM 150 mg I mL−1. Equipment 1. Fluoroscopy unit with spot film device and tilting table 2. Video recorder (for urodynamics) 3. Bladder catheter Patient Preparation The patient empties their bladder prior to the examination. Preliminary Image Coned view of the bladder. Technique To demonstrate vesico-ureteric reflux (this indication is almost exclusively confined to children): 1. Using aseptic technique, the bladder is catheterized. Residual urine is drained. 2. Contrast medium (150 mg I mL−1) is slowly injected or dripped in with the patient supine, and bladder filling is observed by intermittent fluoroscopy. It is important that early filling is monitored by fluoroscopy in case the catheter is malpositioned, e.g. in the distal ureter or vagina. 59 3. Intermittent monitoring is also necessary to identify transient reflux. Any reflux should be recorded. 4. The catheter should not be removed until the radiologist is confident that the patient will be able to micturate, the patient does not tolerate further infusion or until no more contrast medium will drip into the bladder. 5. Older children and adults are given a urine receiver, but smaller children should be allowed to pass urine onto absorbent pads on which they can lie. Children can lie on the table, but adults will probably find it easier to micturate while standing erect. In infants and children with a neuropathic bladder, micturition may be accomplished by suprapubic pressure. 6. Spot images are taken during micturition, and any reflux is recorded. A video recording may be useful. The lower ureter is best seen in the anterior oblique position of that side. Boys should micturate in an oblique or lateral projection, so that spot films can be taken of the entire urethra. 7. Finally, a full-length view of the abdomen is taken to demonstrate any undetected reflux of contrast medium that might have occurred into the kidneys and to record the postmicturition residue. 8. Lateral views are helpful when fistulation into the rectum or vagina are suspected. 9. Oblique views are needed when evaluating for leaks. 10. Stress views are used for urodynamic studies. Aftercare 1. No special aftercare is necessary, but patients and parents of children should be warned that dysuria, possibly leading to retention of urine, may rarely be experienced. In such cases a simple analgesic is helpful, and children may be helped by allowing them to micturate in a warm bath. 2. Most children will already be receiving antibiotics for their recent urinary tract infection—the dose will usually be doubled for 3 days, starting on the day prior to 60 the procedure. Children not already on antibiotics will also usually be prescribed a 3-day course (often trimethoprim). Complications 1. Urinary tract infection 2. Catheter trauma may lead to dysuria, frequency, haematuria and urinary retention. 3. Complications of bladder filling, e.g. perforation from overdistension; prevented by using a nonretaining catheter, e.g. Jacques 4. Catheterization of vagina or an ectopic ureteral orifice 5. Retention of a Foley catheter 61  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪ASCENDING URETHROGRAPHY IN THE MALE‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪62‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Stricture 2. Urethral trauma 3. Fistulae or false passage 4. Congenital abnormalities Contraindications 1. Acute urinary tract infection 2. Recent instrumentation Contrast Medium LOCM 200–300 mg I mL−1 20 mL. Prewarming the contrast medium will help reduce the incidence of spasm of the external sphincter. Equipment 1. Fluoroscopy unit and spot film device 2. Foley catheter 8-F. Patient Preparation Consent. Preliminary Image Coned supine posteroanterior (PA) of the bladder base and urethra. Technique 1. Patient supine 2. The catheter is connected to a 50 mL syringe containing contrast medium and flushed to eliminate air bubbles. 3. Using aseptic technique, the tip of the catheter is inserted so that the balloon lies in the fossa navicularis (i.e. immediately proximal to the meatus within the glans), and its balloon is inflated with 2–3 mL of water to anchor the catheter and occlude the meatus. 63 4. Contrast medium is injected under fluoroscopic control, and steep (30–45°) oblique films are taken. Gentle traction on the catheter is used to straighten the penis over the ipsilateral leg and prevent urethral overlap or foreshortening from obscuring pathology. Depending on the clinical indication, ascending urethrography may be followed by descending micturating cystourethrography to demonstrate the proximal urethra and bladder, assuming there is no contraindication to bladder catheterization, e.g. false passage, stricture. It may be possible to fill the bladder retrogradely via the urethral catheter if the patient is able to relax the bladder neck (and thus avoid bladder catheterization). Aftercare None. Complications Due to the Technique 1. Acute urinary tract infection 2. Urethral trauma 3. Intravasation of contrast medium, especially if excessive pressure is used to overcome a stricture 64  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫&‪RETROGRADE PYELOURETEROGRAPHY‬‬ ‫‪HYSTEROSALPINGOGRAPHY‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪65‬‬ Scientific Content: :‫المحتوى العلمي‬ Indications 1. Demonstration of the site and nature of an obstructive lesion 2. Demonstration of the pelvicalyceal system and potential urothelial abnormalities after previous indeterminate imaging Contraindications Acute urinary tract infection. Contrast Medium HOCM or LOCM 150–200 mg I mL−1 (i.e. not too dense to obscure small lesions) 10 mL. Equipment Fluoroscopy unit. Patient Preparation As for surgery. Preliminary Image Full-length supine AP abdomen when the examination is performed in the x-ray department. Technique In the operating theatre The surgeon catheterizes the ureter via a cystoscope and advances the ureteric catheter to the desired level. Contrast medium is injected under fluoroscopic control and spot films are exposed. Some form of hard copy or soft copy recording is recommended—ideally to the hospital PACS (picture archiving and communication system). 66 In the x-ray department 1. With ureteric catheter(s) in situ, the patient is transferred from the operating theatre to the x-ray department. 2. Urine is aspirated, and under fluoroscopic control, contrast medium is slowly injected. Care should be taken to eliminate air bubbles before injection (as these may mimic pathology such as tumour or calculus). About 3–5 mL is usually enough to fill the pelvis, but if the patient complains of pain or fullness in the loin, the injection should be terminated before this. 3. Images are taken as the catheter is withdrawn. These should include frontal and oblique projections. Aftercare 1. Postanaesthetic observations 2. Prophylactic antibiotics may be used. Complications 1. Pyelosinus extravasation and pyelotubular reflux due to overfilling may result in pain, fever and rigors 2. Introduction of infection 3. Damage or perforation of the ureters or renal pelvis PERCUTANEOUS RENAL CYST PUNCTURE ANDBIOPSYY Indications 1. Diagnostic biopsy: unexplained renal failure, mass, etc. 2. Renal cyst puncture to relieve local symptoms attributable to a cyst Contraindications 1. Bleeding diathesis 2. The possibility of renal hydatid disease 67 Equipment Ultrasound or CT guidance. Patient Preparation Premedication or sedation may be needed. Technique Insertion of the needle can be controlled by either ultrasonography or CT: 1. The patient is placed in the prone position, or as appropriate depending on patient habitus and position of lesion. 2. The kidney, mass or cyst is located directly with US or CT or indirectly, after opacification of the kidneys with i.v. contrast medium. The optimum site for puncture is marked on the skin. For renal biopsy in the investigation of parenchymal disease the lower pole of the left kidney is often preferred. 3. The skin and subcutaneous tissues are infiltrated with 1% lidocaine. 4. The needle is passed directly into the lesion during suspended respiration. US or CT are used to monitor the path of the needle. For cyst puncture, the stilette is removed and the cyst contents are aspirated and examined. 5. For biopsy, the biopsy needle is deployed following confirmation of needle position with imaging. Complications Bleeding—perinephric or haematuria Arteriovenous fistula Pseudoaneurysm 68 HYSTEROSALPINGOGRAPHY indication 1. Infertility—to assess tubal patency 2. Recurrent miscarriages—investigation of suspected incompetent cervix, suspected congenital anomaly of uterus 3. Following tubal surgery to establish tubal patency, poststerilization to confirm obstruction and prior to reversal of sterilization 4. Assessment of the integrity of a caesarean uterine scar (rare) Contraindications 1. During menstruation 2. Pregnancy or unprotected intercourse during the cycle 3. A purulent discharge on inspection of the vulva or cervix, or diagnosed pelvic inflammatory disease (PID) in the preceding 6 months 4. Contrast sensitivity (relative) Contrast Medium High osmolar iodinated contrast material (HOCM) or low osmolar iodinated contrast material (LOCM) 270/300 mg I mL−1 10–20 mL. The contrast medium Equipmentshould be prewarmed to body temperature to avoid tubal spasm. 69 Equipment 1. Fluoroscopy unit with spot film device 2. Vaginal speculum 3. Vulsellum forceps 4. Hysterosalpingography balloon catheter 5-F to 7-F. In patients with narrow cervix or stenosis of cervical os, Margolin hysterosalphingography (HSG) cannula may be used. It has a silicone tip and provides tight occlusion of the cervix for contrast injection. Patient Preparation 1. The appointment is made before day 21, or the examination can be booked between the 4th and 10th days in a patient with a regular 28-day cycle. 2. The patient should abstain from unprotected intercourse between booking the appointment and the time of the examination. 3. Apprehensive patients may need premedication. Analgesics before procedure may also help. 4. Informed consent should be obtained. Technique 1. The patient lies supine on the table with knees flexed, legs abducted. 2. The vulva can be cleaned with chlorhexidine or saline. A disposable speculum is then placed using sterile jelly, and the cervix is exposed. 3. The cervical os is identified using a bright light, and the HSG catheter is inserted into the cervical canal. It is usually not necessary to use a Vulsellum forceps to hold 70 the cervix with forceps, but occasionally this may be necessary. The catheter should be left within the lower cervical canal if cervical incompetence is suspected. 4. Care must be taken to expel all air bubbles from the syringe and cannula, as these would otherwise cause confusion in interpretation. Contrast medium is injected slowly into the uterine cavity under intermittent fluoroscopic observation. 5. Spasm of the uterine cornu may be relieved by intravenous (i.v.) Buscopan or glucagon if there is no tubal spill bilaterally. Prewarming the contrast medium to body temperature and injecting slowly may also help avoid tubal spasm. Note: Opiates increase pain by stimulating smooth muscle contraction. Images The radiation dose should be kept as low as possible. Intermittent screening should be performed to the minimal requirement. Images should demonstrate the following: 1. Endometrial cavity, demonstrating or excluding congenital abnormalities or filling defects. 2. Full view of the tubes demonstrating spill. If occluded, show the extent and level of block. 3. If there is abnormal loculation of contrast, a delayed view may be useful. Aftercare 1. It must be ensured that the patient is in no serious discomfort nor has significant bleeding before she leaves. 2. The patient must be advised that she may have spotting or occasional vaginal bleeding for 1–2 days and pain which may persist for up to 2 weeks. 71 3. Prophylactic broad-spectrum antibiotics are routinely given in several centres and are good practice. Complications Due to the contrast medium Allergic phenomena—especially if contrast medium is forced into the circulation. Due to the technique 1. Pain may occur at the following times: (a) When using the speculum (b) During insertion of the cannula or inflation of balloon, some patients may have developed vasovagal syncope—’cervical shock’. (c) Uterine or tubal distension proximal to a block or spasm (d) With peritoneal irritation during the following day, and up to 2 weeks 2. Bleeding from trauma to the uterus or cervix 3. Transient nausea, vomiting and headache 4. Intravasation of contrast medium into the venous system of the uterus results in a fine lace-like pattern within the uterine wall. It is of little significance when water- soluble contrast medium is used. Intravasation may be precipitated by direct trauma to the endometrium, timing of the procedure near to menstruation or curettage, tubal occlusion or congenital abnormalities. 5. Infection—which may be delayed. Occurs in up to 2% of patients and is more likely when there is a previous history of pelvic infection. 72  ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫المرحلة‪ :‬الثانية‬ ‫المادة‪ :‬فحوصات شعاعية خاصة للجهاز الصفراوي والتناسلي‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫‪Title:‬‬ ‫العنوان‪:‬‬ ‫‪PERCUTANEOUS ANTEGRADE PYELOGRPHY AND‬‬ ‫‪NEPHROSTOMY‬‬ ‫‪Name of the instructor:‬‬ ‫اسم المحاضر‪:‬‬ ‫م‪.‬د‪.‬صفوان سعيد محمد‬ ‫‪Target population:‬‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الثانية‬ ‫قسم تقنيات االشعة‬ ‫‪73‬‬  Scientific Content: :‫المحتوى العلمي‬ This is the introduction of a drainage catheter into the collecting system of the kidney. Indications 1. Renal tract obstruction 2. Pyonephrosis 3. Prior to percutaneous nephrolithotomy 4. Ureteric or bladder fistulae: external drainage (i.e. urinary diversion may allow closure) Contraindications Uncontrolled bleeding diathesis. Contrast Medium As for percutaneous renal puncture. Equipment 1. Puncturing needle: coaxial needle/catheter set or sheathed 18G needle 2. Drainage catheter: at least 6-F pigtail with multiple side holes 3. Guidewires: conventional J-wire ± extra stiff wire 4. US and/or fluoroscopy—usually used in combination Patient Preparation 1. Fasting for 4 h 2. Premedication as required 3. Prophylactic antibiotic Technique Patient position Patient lies prone oblique with a foam pad or pillow under the abdomen to present the kidney optimally. 74 Identifying the collecting system prior to the definitive procedure 1. Freehand or with a biopsy needle attachment; US guidance is the most common method for localizing the kidney and guiding the initial needle puncture into the collecting system. 2. Excretion urography, if adequate residual function and a nondilated system using a parallax technique. 3. Occasionally retrograde injection through an ileal conduit or a ureteric catheter may be used to demonstrate the target collecting system. Site/plane of puncture A point on the posterior axillary line is chosen below the twelfth rib. Having identified the mid/lower pole calyces with US or contrast, the plane of puncture is determined. This will be via the soft tissues and renal parenchyma avoiding direct puncture of the renal pelvis, so that vessels around the renal pelvis will be avoided and the drainage catheter will gain some purchase on the renal parenchyma. There is a relatively avascular plane between the ventral and dorsal parts of the kidney, which affords the ideal access. Techniques of puncture and catheterization The skin and soft tissues are infiltrated with local anaesthetic using a spinal needle. Puncture may then be made using one of the following systems (depending on preference): 1. An 18G sheathed needle, or Kellett needle, using the Seldinger technique for catheterization. Contrast injection is used to confirm successful siting of the needle and for preliminary demonstration of the pelvicalyceal system. On occasion, air is used as a negative contrast medium to enable targeting of a posterior nondependent calyx. Upon successful puncture, a J-guidewire is inserted and coiled within the collecting system; the sheath is then pushed over the wire, which may be exchanged for a stiffer wire. Dilatation is then performed to the size of the drainage catheter, which is then inserted. Care must be taken not to kink the guidewire within the soft 75 tissues. Sufficient guidewire should be maintained within the collecting system, ideally with the wire in the upper ureter to maintain position, and if kinking does occur, the kinked portion of the wire can be withdrawn outside the skin. 2. Coaxial needle puncture systems using a 22/21G puncturing needle that takes a 0.018 guidewire. This affords a single puncture with a fine needle, with insertion of a three-part coaxial system to allow insertion of 0.035 guidewire and then proceeding as in list item (1). 3. The trochar-cannula system, in which direct puncture of the collecting system is made with the drainage catheter already assembled over a trocar. On removal of the trocar, the drainage catheter is advanced further into the collecting system. Having successfully introduced the catheter, it is securely fixed to the skin and drainage commenced. Antegrade pyelography is rarely performed as an isolated procedure; usually it is undertaken following placement of, and via, a nephrostomy catheter, as noted previously. Oblique and AP images are taken with gentle introduction of water-soluble contrast medium. Semierect films may be necessary to encourage contrast medium down the ureters, to show the site and nature of obstruction. Postnephrostomy studies are best performed after a delay of 1–2 days, to allow the patient to recover and be able to cooperate, blood clot to resolve and infected systems to be drained. Aftercare 1. Bed rest for 4 h 2. Pulse, blood pressure and temperature half-hourly for 6 h 3. Analgesia 4. Urine samples sent for culture and sensitivity Complications 76 1. Septicaemia 2. Haemorrhage 3. Perforation of the collecting system with urine leak 4. Unsuccessful drainage 5. Injury to adjacent organs such as lung, pleura, spleen or colon 6. Later catheter dislodgement PERCUTANEOUS NEPHROLITHOTOMY This is the removal of renal calculi through a nephrostomy track. It is often reserved for large complicated calculi, which are unsuitable for extracorporeal shock-wave lithotripsy. Indications 1. Removal of renal calculi 2. Disintegration of large renal calculi Contraindications Uncontrolled bleeding diathesis. Contrast Medium As for percutaneous renal puncture. Equipment 1. Puncturing needle (18G): Kellett (15–20 cm length) or equivalent 2. Guidewires, including hydrophilic and superstiff 3. Track dilating equipment; Teflon dilators (from 7-F to 30-F), metal coaxial dilators or a special angioplasty-type balloon catheter 4. US machine 5. Fluoroscopy facilities with rotating C arm, if possible Patient Preparation 77 1. Full discussion between radiologist/urologist concerning indications and so on 2. Imaging (IVU, CT KUB, CTU) to demonstrate position of calculus and relationship to calyces 3. General anaesthetic 4. Coagulation screen 5. Two units of blood cross matched 6. Antibiotic cover 7. Premedication 8. Bladder catheterization, as large volumes of irrigation fluid will pass down the ureter during a prolonged procedure Technique Preprocedure planning may include a CT KUB and CTU to localize stones and to choose most appropriate access. Patient position As for a percutaneous nephrostomy, usually prone. Methods of opacification of the collecting system 1. Retrograde ureteric catheterization for demonstration and distension of the collecting system may be achieved. In addition, a retrograde occlusion balloon catheter in the ureter will prevent large fragments of stone passing down the ureter 2. Intravenous excretion urography 3. Antegrade pyelography; this also enables distension of the collecting system. Puncture of the collecting system A lower pole posterior calyx is ideally chosen if the calculus is situated in the renal pelvis. Otherwise the calyx in which the calculus is situated is usually punctured. Special care must be taken if puncturing above the twelfth rib, because of the risk of perforating the diaphragm and pleura. Puncture is in an oblique plane from the posterior axillary line through the renal parenchyma. Puncture of the selected calyx 78 is made using a combination of US and a rotating C-arm fluoroscopic facility. On successful puncture, a guidewire is inserted through the cannula, and as much wire as possible is guided into the collecting system. The cannula is then exchanged for an angled catheter, and the wire and catheter are manipulated into the distal ureter. At this stage full dilatation may be performed (single stage) or a nephrostomy tube left in situ with dilatation later (two-stage procedure). Dilatation This is carried out under general anaesthesia. It is performed using Teflon dilators from 7-F to 30-F, which are introduced over the guidewire. Alternatively, metal coaxial dilators or a special angioplasty balloon (10 cm long) are used. A sheath is inserted over the largest dilator or balloon, through which the nephroscope is passed followed by removal of the calculus or disintegration. Removal/disintegration Removal of calculi of less than 1 cm is possible using a nephroscope and forceps. Larger calculi must be disintegrated using an ultrasonic or electrohydraulic disintegrator. Aftercare 1. A large bore soft nonlocking straight nephrostomy tube (sutured) is left in for 24 h following the procedure. 2. Patient care is usually determined by the anaesthetist/urologist. 3. Plain radiograph of the renal area to ensure that all calculi/ fragments have been removed. Complications Immediate 1. Failure of access, dilatation or removal 2. Perforation of the renal pelvis on dilatation 3. Inadvertent access to renal vein and IVC 79 4. Haemorrhage. Less than 3% of procedures should require transfusion. Rarely, balloon tamponade of the tract or embolization may be required. 5. Damage to surrounding structures (i.e. diaphragm, colon, spleen, liver and lung) 6. Problems related to the irrigating fluid Delayed 1. Pseudoaneurysm of an intrarenal artery 2. Arteriovenous fistula RENAL ARTERIOGRAPHY Indications 1. Renal artery stenosis prior to angioplasty or stent placement. Diagnostic arteriography has been replaced generally by MR or CT angiography (MRA or CTA). 2. Assessment of living related renal transplant donors—replaced generally by MRA or CTA 3. Embolization of vascular renal tumour prior to surgery 4. Haematuria particularly following trauma, including biopsy. This may precede embolization. 5. Prior to prophylactic embolization of an angiomyolipoma (AML) or therapeutic embolization of a bleeding AML. Contrast medium Flush aortic L