Liver Abscess PDF - US Abdulsatar-21-47

Liver abscess It is very difficult to differentiate between a bacterial abscess, an amoebic abscess and an infected cyst. All may be either multiple or single, and usually present as hypochogenic masses with strong back walls, irregular outline and internal debris, There may be internal gas.(See Tab...

Liver abscess It is very difficult to differentiate between a bacterial abscess, an amoebic abscess and an infected cyst. All may be either multiple or single, and usually present as hypochogenic masses with strong back walls, irregular outline and internal debris, There may be internal gas.(See Table 2, differential diagnosis of the liver abscesses). Table 2: Differential diagnosis of the liver abscesses Subphrenic and subhepatic abscesses A predominantly echo-free, sharply delineated, crescentic area between the liver and the right hemidiaphragm may be due to a right-sided subphrenic abscess. When using ultrasound to search for the cause of pyrexia of unknown origin, or postsurgical pyrexia, both left and right subphrenic regions should be examined. The posterior aspect of the lower chest should also be scanned to exclude an associated pleural effusion. Occasionally, a subphrenic abscess may extend to the subhepatic space, most commonly between the liver and the kidney. Trauma to the liver Haematomas Ultrasound can reliably detect intrahepatic haematomas, which vary from hyperechogenic to hypoechogenic. However, the clinical history and symptoms may be needed to differentiate haematomas from abscesses. Subcapsular haematomas present as an echo-free or complex (due to blood clots) area located between the capsule of the liver and the underlying liver parenchyma. Extracapsular haematomas present as an echo-free or complex (due to blood clots) area adjacent to the liver but lying outside the capsule. Bilomas Fluid within or around the liver may be bile, resulting from trauma to the biliary tract. It is not possible to distinguish biloma from haematoma by ultrasound imaging. Posttest: :‫االختبار البعدي‬ What are the differential diagnosis of liver lesions? References: :‫المصادر‬ • Palmer, Philip ES, ed. Manual of diagnostic ultrasound. World Health Organization, 2002. • Gibbs JF, Litwin AM, Kahlenberg MS (2004) Contemporary management of benign liver tumors. Surg Clin N Am 84:463–480 ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫المادة‪ :‬فحوصات الموجات فوق الصوتية‬ ‫المرحلة‪ :‬الرابعة‬ ‫العنوان‪:‬‬ ‫‪Title:‬‬ ‫‪Normal gallbladder and biliary tract‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ Introduction: :‫المقدمة‬ Biliary system diseases are a common pathology in medical practice. A frequent situation in everyday practice is a patient with pain in the right upper quadrant, in which the suspicion of biliary disease is the first diagnosis to confirm or exclude. Ultrasound is a reliable method for the evaluation of the biliary system and is the first method of choice when a biliary disease is suspected. Ideally a correct examination of the gallbladder and the biliary tree is performed on fasting patients. The gallbladder is evaluated by means of right subcostal oblique sections while for the hilum evaluation sections perpendicular on the ribs are used. The structures are assessed regarding their size, wall thickness and content. Pretest: :‫االختبار القبلي‬ How does the gall bladder and biliary tract appear by ultrasound? Scientific Content: :‫المحتوى العلمي‬ Indications • Pain in the right upper abdomen: suspected gallstones and/or cholecystitis. • Jaundice. • Palpable right upper abdominal mass. • Recurrent symptoms of peptic ulcer. • Pyrexia of unknown origin. Normal anatomy of the gallbladder On the longitudinal scan the gallbladder will appear as an echo-free, pear-shaped structure. It is very variable in position, size and shape, but the normal gallbladder is seldom more than 4 cm wide (Fig-5). The gallbladder may be mobile. It may be elongated and on scanning may be found below the level of the superior iliac crest (especially when the patient is erect). It may be to the left of the midline. If not located in the normal position, scan the whole abdomen, starting on the right side. The thickness of the gallbladder wall can be measured on transverse scans; in a fasting patient it is normally 3 mm or less and 1 mm when the gallbladder is distended. It is not always easy to identify the normal main right and left hepatic biliary ducts, but when visible they are within the liver and appear as thin-walled tubular structures. However, the common hepatic duct can usually be recognized just anterior and lateral to the crossing portal vein, and its cross-section at this level should not exceed 5 mm. The diameter of the common bile duct is variable but should not exceed 9 mm near its entrance into the pancreas. Fig-5: Longitudinal scan: normal full gallbladder Nonvisualization of the gallbladder There are various reasons why the gallbladder may not be seen by ultrasound: • The patient has not been fasting: re-examine after an interval of at least 6 hours without food or drink. • The gallbladder lies in an unusual position. • The gallbladder is congenitally hypoplastic or absent. • The gallbladder is shrunken and full of stones (calculi), with associated acoustic shadowing. • The gallbladder has been removed surgically: examine the abdomen for scars and ask the patient (or relatives). • The examiner is not properly trained or experienced: ask a colleague to examine the patient. • There are very few pathological conditions (other than congenital absence or surgical removal) that result in persistent nonvisualization of the gallbladder by ultrasound. Posttest: :‫االختبار البعدي‬ What are the indications of the gallbladder and biliary tract scanning? What are the causes of non-visualization of the gall bladder? References: :‫المصادر‬ • Palmer, Philip ES, ed. Manual of diagnostic ultrasound. World Health Organization, 2002. • Popescu, A., & Sporea, I. (2010). Ultrasound examination of normal gall bladder and biliary system. Medical Ultrasonography, 12(2), 150-152. ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫المادة‪ :‬فحوصات الموجات فوق الصوتية‬ ‫العنوان‪:‬‬ ‫المرحلة‪ :‬الرابعة‬ ‫‪Title:‬‬ ‫‪Abnormal gallbladder and biliary tract: distended gallbladder, Acute‬‬ ‫‪cholecystitis, Echoes within the gallbladder‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ :‫المقدمة‬ Introduction: A distended gallbladder is not usually a serious condition, it can sometimes lead to more serious problems that can lead to potentially life-threatening complications if left untreated. If you experience any of the symptoms listed below, it is important to see a doctor right away so that the underlying cause can be properly diagnosed and treated. Also, Rupturing of the distended gallbladder is a medical emergency that requires immediate treatment. A distended gallbladder is a condition when the gallbladder becomes swollen or enlarged. Also, a distended gallbladder does not function properly. The gallbladder is a small, pear-shaped organ that stores bile, a substance produced by the liver that helps to break down fats. Pretest: What are the causes of gallbladder distended? :‫االختبار القبلي‬ Scientific Content: :‫المحتوى العلمي‬ Enlarged (distended) gallbladder The gallbladder is enlarged if it exceeds 4 cm in width (transverse diameter). The normal gallbladder may appear distended when the patient is de- hydrated, has been on a low-fat diet or on intravenous nutrition, or has been immobilized for some time. If there is no clinical evidence of cholecystitis, and fi the gallbladder wall does not appear thickened on ultrasound, give the patient a fatty meal and repeat the ultrasound examination in 45 minutes to 1hour. A normal gallbladder will contract. If there is no contraction, search for: • A gallstone or other cause of obstruction within the cystic duct. The hepatic and bile ducts will be normal. If there is no internal obstruction, there may be a mass or lymph node pressing externally on the duct. • A stone or other obstruction in the common bile duct. The common hepatic duct will be dilated (over 5 mm diameter). Examine the common bile duct for Ascaris. • If the gallbladder is distended with thickened walls (greater than 5 mm) and filled with fluid, there may be an empyema: local tenderness is likely. Check the patient clinically. • If the gallbladder is distended with thin walls and filled with fluid, there may be a mucocele. This does not usually result in local tenderness. Acute cholecystitis Clinically, acute cholecystitis usually associated with pain in the right upper abdomen and with local tenderness when the transducer is (carefully) applied near the gallbladder. There may be one or more gallstones, probably including a stone in the gallbladder neck or in the cystic duct. The walls of the gallbladder are likely to be thickened and oedematous, and, therefore, the gallbladder is not always distended. If the gallbladder has perforated, there is usually fluid adjacent to it. Echoes within the gallbladder Mobile internal echoes with shadowing • Gallstones can be recognized as bright intraluminal echogenic structures with an acoustic shadow. The stones may be single or multiple, large or small, calcified or non-calcified. The gallbladder walls may be normal or thickened (Fig-6). • When gallstones are suspected but not seen clearly on routine scans, rescan with the patient oblique or erect. Most gallstones will change position within the gallbladder as the patient moves. • If there is still any doubt, scan the patient in the hands/knees position. The gallstones will move anteriorly. This position may also be useful fi there is excessive bowel gas. Fig-6: Transverse scan: a single stone in the gallbladder Mobile internal echoes without shadowing Scans should be taken in different positions. The common causes are: • Gallstones. Note that there will be no acoustic shadow if the stones are smaller than the diameter of the ultrasound beam. • Gallbladder sludge. This is thickened bile which produces fine dependent echoes that move slowly with a change in the position of • the patient, unlike stones which tend to move quickly. • Pyogenic debris. • Blood clots. • Hydatid membranes. Scan the liver for cysts. • Ascaris and other parasites. Nonmobile internal echoes with shadowing The commonest cause is an impacted calculus: search for other calculi. The calcification may also be in the gallbladder wall: if the wall is also thickened, there may be acute or chronic cholecystitis, but it may be difficult to exclude an associated carcinoma. Nonmobile internal echoes without shadowing • The most common cause is a polyp. It may be possible to identify the pedicle by using different scanning projections. There should be no acoustic shadowing, and changing the patient's position will not move the polyp but may alter its shape. Malignant disease may resemble a polyp but is more often associated with thickening of the gallbladder wall and does not usually have a pedicle. A malignant tumour is less likely to change its shape when the patient changes position. • A septum or fold within the gallbladder is not likely to be of any clinical significance. • A malignant tumour. Posttest: :‫االختبار البعدي‬ Mention the clinical and sonographic features of acute cholecystitis? What are the internal echoes within gallbladder without shadowing? References: :‫المصادر‬ • Palmer, Philip ES, ed. Manual of diagnostic ultrasound. World Health Organization, 2002. ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫المادة‪ :‬فحوصات الموجات فوق الصوتية‬ ‫العنوان‪:‬‬ ‫المرحلة‪ :‬الرابعة‬ ‫‪Title:‬‬ ‫‪Thick gallbladder walls, Small gallbladder, Gallbladder in jaundice‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ Introduction: :‫المقدمة‬ Thickening of the gallbladder wall is a relatively frequent finding on diagnostic imaging studies. Historically, a thick-walled gallbladder has been regarded as proof of primary gallbladder disease, and it is a well-known hallmark feature of acute cholecystitis. The finding itself, however, is nonspecific and can also be found in a variety of conditions unrelated to intrinsic gallbladder disease. Diffuse gallbladder wall thickening may produce a diagnostic problem because it occurs in symptomatic and asymptomatic patients and in patients with and those without an indication for cholecystectomy. Misinterpretation of the cause of this imaging finding can lead to an unnecessary cholecystectomy in patients without intrinsic gallbladder disease and, conversely, misdiagnosis in patients who do require a cholecystectomy may result in delayed treatment with increased morbidity. In this essay, we discuss and illustrate the various causes of a thickened gallbladder wall because knowledge of its differential diagnosis is essential for the correct interpretation of this finding. Pretest: :‫االختبار القبلي‬ What is the association between gallbladder wall and acute cholecystitis? Scientific Content: :‫المحتوى العلمي‬ Sonography, CT, and MRI all allow direct visualization of the normal and thickened gallbladder wall. Traditionally, sonography is used as the initial imaging technique for evaluating patients with suspected gallbladder disease because of its high sensitivity in the detection of gallbladder stones, its real-time character, and its speed and portability. However, CT has become popular for evaluating the acute abdomen and often is the first technique to show gallbladder wall thickening, or CT may be used as an adjunct to an inconclusive sonography examination or for staging of disease. The potential value of MRI in the evaluation of gallbladder disease , but it still plays little role. The normal gallbladder wall appears as a pencil-thin echogenic line on sonography and is usually visible on CT as a thin rim of soft-tissue density that enhances after contrast injection. The thickness of the gallbladder wall depends on the degree of gallbladder distention, and pseudothickening can occur in the postprandial state. A thickened gallbladder wall measures more than 3 mm, typically has a layered appearance at sonography, and frequently contains a hypodense layer of subserosal edema that mimics pericholecystic fluid at CT. Thick gallbladder walls Generalized thickening The thickness of the gallbladder wall is normally less than 3 mm and should not exceed 5 mm. When the thickness is between 3 m m and 5 mm, careful clinical correlation is needed. Generalized thickening of the gallbladder wall can occur in the following conditions: • Acute cholecystitis. • Chronic cholecystitis. • Hypoalbuminaemia resulting from cirrhosis. Check for ascites, dilated portal veins and splenomegaly. • Congestive cardiac failure. Check for ascites, pleural effusions, and dilated inferior vena cava and hepatic veins. Examine the patient. • Chronic renal insufficiency. Examine the kidneys and the urine. • Multiple myeloma. • Hyperplasticcholecystosis. Localized thickening Local thickening of the gallbladder walls may be due to the following: • Mucosal folds. • Polyp. • Primary or secondary carcinoma of the gallbladder. Small gallbladder • The patient may recently have had a meal containing fat and the gallbladder has contracted. • Chronic cholecystitis: check for thickened gallbladder walls and for gallstones within the gallbladder. Jaundice When the patient is jaundiced, ultrasound can usually differentiate between nonobstructive and obstructive jaundice, by showing the dilatation of the biliary system. Normal bile ducts - Extrahepatic ducts. It may be difficult to see the extrahepatic bile ducts. - Intrahepatic ducts. The intrahepatic ducts are best seen on the left side of the liver in deep inspiration. It is not easy to see the normal intrahepatic ducts on ultrasound because they are often too small and thin-walled. • Maximum diameter of normal common hepaticduct: less than5 mm • Maximum diameter of normal common bileduct: less than 9mm • Maximum diameter of common bile duct post-cholecystectomy:10-12mm Sometimes following surgery, and in patients over 70 years of age, the common bile duct may be a few millimetres wider (i.e. 12-14 mm). Add 1 mm to all of the measurements above for each decade over 70 years of age. Gallbladder in jaundice 1. If the gallbladder is distended, the obstruction usually affects the common bile duct (e.g. calculus, Ascaris,pancreatitis or carcinoma). The hepatic ducts will also be distended. 2. If the gallbladder is not distended or is very small, obstruction is unlikely or the obstruction is above the level of the cystic duct (e.g. enlarged lymph nodes or tumour near the porta hepatis). Posttest: :‫االختبار البعدي‬ What are the possible causes of generalized thickened of gall bladder wall? References: :‫المصادر‬ • Palmer, Philip ES, ed. Manual of diagnostic ultrasound. World Health Organization, 2002. • Van Breda Vriesman, A. C., Engelbrecht, M. R., Smithuis, R. H., & Puylaert, J. B. (2007). Diffuse gallbladder wall thickening: differential diagnosis. American Journal of Roentgenology, 188(2), 495-501. ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫المادة‪ :‬فحوصات الموجات فوق الصوتية‬ ‫المرحلة‪ :‬الرابعة‬ ‫العنوان‪:‬‬ ‫‪Title:‬‬ ‫‪Normal and abnormal pancreas‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ :‫المقدمة‬ Introduction: Pancreatic ultrasound can be used to assess for pancreatic malignancy, pancreatitis and its complications, as well as for other pancreatic pathology. As ultrasound (US) is simple and less invasive than other imaging modalities, this technique is widely used for mass screening. However, visualizing the entire pancreas due to complicated anatomy, obesity and overlying gas can be difficult. US plays a key role in the diagnosis of pancreatic carcinoma (PC). To detect these forms of PC, main pancreatic duct (MPD) dilatation (3 mm or more) and pancreatic cysts (5 mm or larger) are US findings of high-risk individuals (HRIs), and these subjects should be observed periodically. Scanning maneuvers are also important for both screening for PC and follow-up of HRIs. As lesions in the groove area and ventral pancreas do not affect the MPD or extrahepatic bile duct, we should pay attention to these areas. Visualization of the tail is also challenging due to gas and stool in the alimentary tract. As the position of the pancreas changes depending on the body posture, and several different body positions should be employed, such as the right lateral decubitus, sitting, and upright positions, rather than only applying strong compression with the transducer. In cases with poor visualization, the liquid-filled stomach method is highly recommended. Pretest: What is the echo pattern and size of normal pancreas? :‫االختبار القبلي‬ Scientific Content: :‫المحتوى العلمي‬ Indications • Midline upper abdominal pain, acute or chronic. • Jaundice. • Upper abdominal mass. • Persistent fever, especially with upper abdominal tenderness. • Suspected malignant disease. • Recurrent chronic pancreatitis. • Suspected complications of acute pancreatitis, especially pseudocyst or abscess. • Polycystic kidneys: cysts in the liver or spleen. • Direct abdominal trauma, particularly in children. • The pancreas can be very difficult to identify, especially the tail. Gas If bowel gas obscures the image: - Try gentle compression with the transducer or use decubitus views, both right and left. - If necessary, give the patient 3 or 4 glasses - of water, wait a few minutes to allow the bubbles to disperse and then repeat the - examination with the patient sitting or standing, viewing the pancreas through the water-filled stomach. Transverse scanning Start with transverse scans across the abdomen moving downwards towards the feet until the splenic vein is seen as a linear, tubular structure with the medial end broadened. This is where it is joined by the superior mesenteric vein , at the level of the body of the pancreas . The superior mesenteric artery will be seen in cross-section just below the vein. By angling and rocking the transducer, the head and the tail of the pancreas may be seen. Continue transverse scans downwards to visualize the head of the pancreas and the uncinate process (if present) between the inferior vena cava and the portal vein. Normal pancreas The pancreas has about the same echogenicity as the adjacent liver and should appear homogeneous. However, the pancreatic echogenicity increases with age. The outline of the normal pancreas is smooth. When scanning the pancreas, certain anatomical landmarks should be identified, in the following order: • Aorta • Inferior vena cava • Superior mesenteric artery • Splenic vein • Superior mesenteric vein • Wall of the stomach • Common bile duct The essential landmarks are the superior mesenteric artery and the splenic vein. Normal pancreatic size There is great variability in the size and shape of the pancreas. The following guidelines may be helpful. • The average diameter of the head of the pancreas: 2.8 cm. • The average diameter of the medial part of the body of the pancreas: less than 2 cm. • The average diameter of the tail of the pancreas: 2.5 cm. • The diameter of the pancreatic duct should not exceed 2 mm. Small pancreas The pancreas is usually smaller in elderly people, but this is not of clinical significance. When there is overall atrophy of the pancreas, the decrease in size is usually uniform throughout the pancreas. If there appears to be atrophy of the tail of the pancreas alone (the head appearing-normal), then a tumour in the head oft h e pancreas must be suspected. The head must be scanned carefully because chronic pancreatitis in the body and tail may be associated with a slow- growing tumour in the head of the pancreas (Fig-7). If the pancreas is small and irregularly hyperechogenic and non- homogeneous compared with the liver, the cause is usually chronic pancreatitis. Fig-7: A small. nonhomogeneous pancreas with calcifications due to chronic pancreatitis Diffuse enlargement of the pancreas In acute pancreatitis, the pancreas may be diffusely enlarged and either normal or hypochogenic compared with the adjacent liver. The serum amylase is usually elevated, and there may be local ileus due to bowel irritation. When the pancreas is irregularlyhyperechogenic and diffusely enlarged, there is usually acute pancreatitis superimposed on chronic pancreatitis. Focal enlargement (noncystic) Almost all pancreatic tumours are hypochogenic compared with the normal pancreas. It is not possible to distinguish between focal pancreatitis or pancreatic tumour by ultrasound alone. Even if the serum amylase is elevated, repeat the ultrasound examination in 2 weeks to assess the change. Tumour and pancreatitis can co-exist.When the pattern is mixed, biopsy is needed. Pancreatic cysts True pancreatic cysts are rare. They are usually single, echo-free, smooth cavities filled with fluid. Small multiple cysts may be con- genital. An abscess or haematoma in the pancreas will appear as a complex mass, often associated with severe pancreatitis. Pseudocysts following trauma or acute pancreatitis are not uncommon; they may increase in size and rupture. Such cysts can be single or multiple. In the early stages they are complex, with internal echoes and ill-defined walls, but eventually these cysts become smooth-walled and echo-free. Pancreatic cystadenoma or other cystic tumours usually appear on ultrasound as multiseptate cystic masses with associated solid components. Hydatid cysts are unusual in the pancreas. Calcification in the pancreas Ultrasound is not the best way to assess pancreatic calcification. A supine anteroposterior radiograph of the upper abdomen is preferable. Calcification within the pancreas can produce acoustic shadowing. However, fi the calcification is very small, there may only be bright discrete echoes without shadowing. Calcification is usually due to: • Chronic pancreatitis. • Calculi in the pancreatic duct. • Biliary calculi in the distal common bile duct can be mistaken for pancreatic calcification. There is usually dilatation of the proximal bile duct. Dilatation of the pancreatic duct The normal maximum internal diameter of the pancreatic duct is 2 mm. The causes of dilatation of the pancreatic duct are: • Tumour of the head of the pancreas or of the ampulla of Vater. Both are usually associated with jaundice and dilatation of the biliary tract. • Calculus in the common pancreatic duct. • Calculus in the intrapancreatic duct. • Chronic pancreatitis • Postoperative strictures following Whipple's operation or partial pancreatectomy. The clinical history should be verified with the patient or relatives if necessary. Posttest: :‫االختبار البعدي‬ How does the pancreas appear in elderly people? References: :‫المصادر‬ • Palmer, Philip ES, ed. Manual of diagnostic ultrasound. World Health Organization, 2002.