Ultrasound Imaging PDF - Al-Kitab University 2012

Ministry of Higher Education and Scientific Research Al-Kitab University College of Medical Techniques Radiology and Ultrasonic .Dept 4th Stage Ultrasound Imaging First Semester Theory L-3 Dr. Rezan H Muhammed Liver abnormality Liver abnormality 1.Focal 2.Diffuse Focal 1.Hyperechoic liver l...

Ministry of Higher Education and Scientific Research Al-Kitab University College of Medical Techniques Radiology and Ultrasonic .Dept 4th Stage Ultrasound Imaging First Semester Theory L-3 Dr. Rezan H Muhammed Liver abnormality Liver abnormality 1.Focal 2.Diffuse Focal 1.Hyperechoic liver lesions. 2.Hypoechoic halo sign / target lesions. 3.Simple hepatic cyst. 4.Hepatic haemangioma. 5.Focal nodular hyperplasia. 6.Hepatic adenoma. 7.Hepatic metastases. 8.Hepatic abscess. Diffuse •acute hepatitis •cirrhosis •hyperechoic liver -diffuse hepatic steatosis •coarse hepatic echotexture •generalized decrease in hepatic echogenicity •starry sky appearance" of the liver diffuse hepatic steatosis starry sky appearance" of the liver Hyperechoic liver lesions A hyperechoic liver lesion on ultrasound can arise from a number of entities, both benign and malignant. A benign hepatic hemangioma is the most common entity encountered. Benign 1.hepatic hemangioma: commonest hyperechoic liver lesion by far (present in 4% of the population) 2.focal nodular hyperplasia. 3.hepatic adenoma with high fat content. 4.focal fatty change: focal hepatic steatosis. 5.hepatic angiomyolipoma. 6.inflammatory pseudotumor of the liver. 7.lipoma. focal hepatic steatosis hepatic adenoma hepatic hemangioma Liver angiomyolipoma Malignant 1.hepatic metastases 2.hepatocellular carcinoma: particularly in a cirrhotic liver 3.cholangiocarcinoma(bile duct cancers) hepatic metastases hepatocellular carcinoma (bile duct cancers) cholangiocarcinoma Sonographic halo sign is used in a number of situations. They include: hypoechoic halo sign (also known as target or bull's eye sign) in liver metastases: used in hepatobiliary imaging, is a concerning feature for malignant lesion if the lesion is a hyperechoic liver lesion Sonographic halo sign Sonographic halo sign Sonographic halo sign liver transplant hepatic arterial resistive index: The resistive index (RI) is the commonest Doppler parameter used for hepatic arterial evaluation. The usual range in normal, as well as post-transplant individuals, is between 0.55 and 0.8. It is measured by: Resistive index (RI) = (peak systolic velocity - end-diastolic velocity)/peak systolic velocity Hepatic arterial resistive index is most often assessed during the evaluation of a liver transplant. In this setting, a low RI is usually more specific for disease than a high RI (the opposite situation from a renal transplant) . Low RI: more specific for disease in a liver transplant. The biliary tree The biliary tree is a system of vessels that directs there secretions from the liver, gallbladder and pancreas through a series of ducts into the duodenum. The exit hole into the duodenum is called the papilla of Vater. The biliary tract refers to the path by which bile is secreted by the liver then transported to the duodenum, the first part of the small intestine. The biliary tract is often referred to as a tree because it begins with many small branches that end in the common bile duct Scanning technique The patient should be fasted. Begin with the patient supine. Assess the pancreas and visualise the Common Bile Duct (CBD) in the head of pancreas. Follow the CBD back into the liver at porta hepatis. Measure the diameter of the extrahepatic bile duct. Most authors accept a diameter of 6 mm or less, with a range of 4–8 mm, for a normal extrahepatic bile duct at the level of the common hepatic duct at the porta hepatis. biliary tree abnormality 1.dilated intrahepatic bile ducts 2.bile duct wall thickening 3.cholangiocarcinoma 4.Mirizzi syndrome: is defined as common hepatic duct obstruction caused by extrinsic compression from an impacted stone in the cystic duct 5.Choledocholithiasis(also called bile duct stones or gallstones in the bile duct) The normal range of CBD diameter was 1.8mm to 5.9 mm. However, 65% of the study participants had a common bile duct diameter of < 4 mm. Choledocholithiasis Choledocholithiasis denotes the presence of gallstones within the bile ducts (including the common hepatic duct/common bile duct). . Cholangiocarcinomas (bile duct cancers) are malignant epithelial tumors arising from the biliary tree, excluding the gallbladder or ampulla of Vater. Cholangiocarcinoma is the second most common primary hepatobiliary malignancy after hepatocellular carcinoma (HCC). They tend to have a poor prognosis and high morbidity. Ultrasound feature of gallstone Ministry of Higher Education and Scientific Research Al-Kitab University College of Medical Techniques Radiology and Ultrasonic .Dept 4 th Stage Ultrasound Imaging First Semester Theory L-4 Dr. Rezan H Muhammed ULTRASOUND OF THE GALLBLADDER Normal ULTRASOUND OF THE GALLBLADDER - Normal GB ANATOMY Anatomy of the Gallbladder: The gallbladder is a pear shaped organ that is about 7 to 10 centimeters long (3 to 4 inches) and 2 to 3 centimeters wide (about 1 inch). It has the ability to hold about 50 milliliters of bile which can be emptied via the cystic duct (gallbladder duct) into the common bile duct. The gallbladder The gallbladder Ultrasound of the Gallbladder-Protocol Role of Ultrasound : •Always tailor your scan to the clinical signs. •Always take a thorough history including previous cancer diseases, blood results, family history and past surgery. •Perform an initial overall scan without imaging to get an idea what pathology there might be and how it might relate to the patients current complaint. Limitations Often you will have problems with bowel gas overlying the gallbladder. Ways to overcome this include : •Roll the patient into a left lateral decubitus or erect position. •Use the liver as a window especially when rolling the pt onto their left side . • Deep inspiration / expiration . • Distend the abdomen against the probe. (ask the patient to push their stomach out as if they are pregnant!) Patient position Generally the gallbladder is best viewed in the left lateral decubitus position. However it can be viewed with the patient supine and erect. Erect views may be useful to determine if stones are mobile or impacted in the neck. Patient Preparation Fast for 6 hours. No food or drink. Preferably book the appointment in the morning to reduce bowel gas. Scanning Technique Looking supine, left lateral decubitus and erect . • Use the liver as a window especially when rolling the pt onto their left side • Measure the wall <3mm . •If the gallbladder enlarged>10cm in length •Check with colour Doppler for increased vascularity of the wall •Assess the cystic duct, neck , body and fundus (sometimes there is a phrygian cap) SCAN PLANE Normal Scanning Position to take advantage of using the liver as a window and displacing the bowel. Normal gallbladder A normal Gallbladder should be thin walled (<3mm) and anechoic.It is a pear shaped saccular structure for bile storage in the Right Upper Quadrant. Its size varies depending on the amount of bile. Fasted it will be approximately 10cm long. Folds are commonly seen and are normal. Make note if pathology such as calculi are contained within a compartment created by a fold. Phrygian cap: A relatively common,inversion of the distal fundus of the gallbladder into the body.It may become adherent. It is an anatomic variant or acquired abnormality BILIARY TREE ANATOMY The biliary tree descends from the canaliculi at the hepatocytes, gradually enlarging and merging to the right and left hepatic ducts. These 2 merge at porta hepatis to form the Common Hepatic Duct(CHD). The Common Bile Duct (CBD) is formed by the junction of the cystic duct with the CHD. The CBD traverses through the head of the pancreas entering the duodenum at the Ampulla of Vater through the Sphyncter of Oddi. Prior to draining into the duodenum the CBD is joined by the pancreatic duct. A smaller accessory pancreatic duct and sphincter is usually present (but rarely visible). ULTRASOUND OF THE BILIARY TREE - Normal EXTRAHEPATIC JUNCTION •A common anatomic variation is to have an extrahepatic junction of the right/left hepatic ducts.(20% of people). •It is useful to make note of this in the report, particularly if it is a very distal junction. During cholecystectomy surgery, the common duct is cannulated to image for duct calculi which may be missed. Also to avoid mistaking the RHD for the cystic duct. •A less common, but important variation, is for the right hepatic duct to join the cystic duct rather than merge with the LHD Ultrasound of the Biliary Tree -Protocol Role of Ultrasound : Ultrasound is the primary tool for assessment of the structure of the biliary tree. Whilst studies on have been performed on functional assessment of CBD diameter (pre/post fatty meal), they are not easily or objectively reproducable. Limitations 1.Non fasted patients . 2.Large habitus patients Equipment Selection Use of a curvi-linear probe 3-Mhz depending on patient habitus. • If the gallbladder is superficial in a thin patient, a linear array may be utilized however reverberation from the anterior abdominal wall becomes an issue. • To minimze this artefact, try reducing transducer pressure • Good colour / power / Doppler capabilities when assessing vessels Versus ducts or vascularity of the gallbladder wall. • Be prepared to change frequency output of probe (or probes) to adequately assess both superficial and deeper structures. • Throughout a comprehensive investigation the patient may need to be supine, erect or left decubitus. Utilise inspiration/expiration and asking the patient to 'puff their stomach out' like a pregnant. This can move anatomy out from beneath the ribs and help mobilize bowel gas obscuring view. Scanning Technique The patient should be fasted. Begin with the patient supine. Assess the pancreas and visualise the Common Bile Duct (CBD) in the head of pancreas. Follow the CBD back into the liver at porta hepatis. Measure the diameter of the extrahepatic bile duct. Gall Bladder abnormalities 1.Phrygian cap:is the most common abnormality of gallbladder shape, occurring in 1% to 6% of the population. This deformity is characterized by a fold or septum of the gallbladder between the body and fundus. Congenital Abnormalities of the Gallbladder 1.Agenesis of GB: Congenital absence of GB. 2.Hypogenesis of GB: Rudimentary or atretic GB 3.Bilobed GB: 2 completely divided GB cavities with a common cystic duct 4.Duplicated GB: Duplicated GB with separate cystic ducts for each moiety 5.Multiseptate GB: Single GB with “honeycomb” appearance due to innumerable internal septations 6.Hourglass GB: Hourglass shape of GB may be congenital or acquired due to chronic inflammation 7.Congenital diverticulum: Usually true diverticulum that can be seen anywhere in GB 8.Phrygian cap: Folding of GB fundus (considered normal variant given its high prevalence) 9.Ectopic GB: Ectopically positioned GB has been reported in nearly every possible position in abdomen and pelvis. – Most common ectopic positions are intrahepatic, under left hepatic lobe, transverse, and retrohepatic. 10.Floating or wandering GB: Mobile GB due to long mesentery, completely covered by peritoneum – High risk of GB torsion and gangrenous inflammation Septations within the GB Ultrasound demonstrates many septations within the GB, creating a “honeycomb” appearance, characteristic of a multiseptate GB Emphysematous cholecystitis Emphysematous cholecystitis: is a rare form of acute cholecystitis where gallbladder wall necrosis causes gas formation in the lumen or wall. It is a surgical emergency, due to the high mortality from gallbladder gangrene and perforation. Chronic Cholecystitis Ministry of Higher Education and Scientific Research Al-Kitab University College of Medical Techniques Radiology and Ultrasonic .Dept 4th Stage Ultrasound Imaging First Semester Theory L-2 Dr. Rezan H Muhammed Ultrasound of liver A liver scan may be done to check for diseases such as liver cancer , hepatitis or cirrhosis . Lesions such as tumors, abscesses, or cysts of the liver, spleen may be seen on a liver scan. By ultrasound the normal liver span is usually < 16 cm in the midclavicular scan. The exact dimention of normal liver span is (6-15)cm. Lobes of the Liver: Traditionally, the liver is divided into four lobes: left, right, caudate, and quadrate. The lobes are further divided into lobules. The quadrate lobe is located on the inferior surface of the right lobe. The caudate lobe is located between the left and right lobes in an anterior and superior location Liver Segmental Anatomy Blood Supply The liver receives a blood supply from two sources. The first is the hepatic artery which delivers oxygenated blood from the general circulation. The second is the portal vein delivering deoxygenated blood from the small intestine containing nutrients. The blood flows through the liver tissue to the hepatic cells where many metabolic functions take place. The blood drains out of the liver via the hepatic vein. The liver tissue is not vascularised with a capillary network as with most other organs, but consists of blood filled sinusoids surrounding the hepatic cells. Role of Ultrasound To assess the: Size Capsular contour (smooth, coarse, lobulated) Parenchymal echogenicity Vascularity Biliary tree Masses or collections Preparation Ideally, fast the patient for 6 hours to reduce bowel gas and prevent gall bladder contraction. Scanning Technique Begin doing a full sweep through the liver. You will need the patient take deep inspirations to fully visualise the superior borders of the liver. Look in transverse up and down the left lobe from a subcostal approach. Look in transverse through the right lobe subcostally or intercostally. Roll the patient in a left lateral decubitus position for assessment of the Rt lobe only after checking for fluid. Bowel gas can overlie the liver in a subcostal approach, so getting the patient to distend their abdomen can help with visualisation. Look For 1.Homogeneous v's Attenuative(normal v's fatty) 2.Smooth v's coarse echotexture 3.Size: To measure the size of the liver, use a sagittal approach in the mid clavicular line. Measure from the diaphragm to the inferior border. This can be very subjective. Also look at the lower edge of liver in relation to the Rt kidney.It should finish half way down the kidney. PROBE POSITIONING TO SCAN THE LIVER Parasagittal Scan Plane The Liver and Rt Kidney are visualised in this view Intercostal Scan Plane The Middle and Rt Hepatic Vein are visualised in this view Subcostal Scan Plane. The probe is angled cephalad under the ribs to avoid any bowel or ribs shadowing over the liver Rt Portal Vein is shown coursing transversely in this view Scan Plane Left Lobe of Liver. The probe is in the epigastric region just below the sternum Normal Anatomy seen in the Transverse View of the Left Lobe The Portal Vein should have constant forward flow into the liver (hepatopetal flow) .As seen in next image, the colour is red ,which is set for movement towards the probe. Be very careful to make sure you look at the colour box on the side of the image to know the setting. If there is flow reversal,this is hepatofugal (tip: Fugitive= run away) and represents portal hypertension.