Normal and Abnormal Liver in Ultrasound PDF

Introduction: :‫المقدمة‬ What is ultrasound? Ultrasound is the name given to high-frequency sound waves, over 20000 cycles per second (20 kHz). These waves, inaudible to humans, can be transmitted in beams and are used to scan the tissues of the body. Different tissues alter the waves in different...

Introduction: :‫المقدمة‬ What is ultrasound? Ultrasound is the name given to high-frequency sound waves, over 20000 cycles per second (20 kHz). These waves, inaudible to humans, can be transmitted in beams and are used to scan the tissues of the body. Different tissues alter the waves in different ways: some reflect directly while others scatter the waves before they return to the transducer as echoes. The reflected ultrasound pulses detected by the transducer need to be amplified in the scanner. The echoes that come from deep within the body are more attenuated than those from the more superficial parts, and therefore require more amplification. Pretest: What is ultrasound and how is generated? :‫االختبار القبلي‬ Scientific Content: :‫المحتوى العلمي‬ Ultrasound generators The ultrasound waves are generated by a piezoelectric transducer which is capable of changing electrical signals into mechanical (ultrasound) waves. The same transducer can also receive the reflected ultrasound and change it back into electrical Signals. Transducers are both transmitters and receivers of ultrasound. Different modes of ultrasound The various modes show the returning echoes in different ways: A-mode: With this type of ultrasound unit, the echoes are shown as peaks, and the distances between the various structures can be measured. This pattern is not usually displayed but similar information is used to build the two-dimensional B-mode image. B-mode: This type of image shows all the tissue traversed by the ultrasound scan. The images are two-dimensional and are known as B-mode images or B-mode sections. If multiple B-mode images are watched in rapid sequence, they become real-time images. Real-time: This mode displays motion by showing the images of the part of the body under the transducer as it is being scanned. The images change with each movement of the transducer or if any part of the body is moving (for example, a moving fetus or pulsating artery). The movement is shown on the monitor in real time, as it occurs. In most real-time units, it is possible to "freeze" the displayed image, holding it stationary so that it can be studied and measured if necessary. M-mode: is another way of displaying motion. The result is a wavy line. This mode is most commonly used for cardiac ultrasound Ultrasound terms/ Glossary • Acoustic enhancement: The increased echogenicity (echo brightness) of tissues that lie behind a structure that causes little or no attenuation of the ultrasound waves, such as a fluid-filled cyst. The opposite to acoustic enhancement is acoustic shadowing • Acoustic shadowing: The decreased echogenicity of tissues that lie behind a structure that causes marked attenuation of the ultrasound waves. The opposite to acoustic shadowing is acoustic enhancement. • Acoustic window: A tissue or structure that offers little obstruction to the ultrasound waves, and can therefore be used as a route to obtain images of a deeper structure. For example. when the bladder is full of urine it forms an excellent acoustic window through which the pelvic structures may be imaged. Similarly, it is better to image the right kidney through the liver than through the thick muscles of the back. In this case the liver is the acoustic window. • Anechogenic (anechoic): Without echoes; echo-free. For example, normal urine and bile are anechogenic, i.e. they have no internal echoes. • Cyst: A fluid-filled structure (mass) with thin walls. A simple cyst characteristically has anechogenic (echo-free) content. with strong back wall reflections and enhancement of the echoes behind the cyst. A cyst can be histologically benign or malignant. • Debris: Echogenic solid masses (of various sizes and shapes. with irregular outlines) within a fluid-filled mass. May be mobile. changing with the patient's position or movement. • Hyperechogenic (hyperechoic): Describes tissues that create brighter echoes than adjacent tissues, e.g. bone, perirenal fat, the wall of the gallbladder, and a cirrhotic liver (compared with normal liver). • Hypoechogenic (hypoechoic): Describes tissues that create dimmer echoes than adjacent tissues, e.g. lymph nodes, some tumours and fluid. It is important to note that fluid is not the only hypoechogenic material. • Internal echoes: Ultrasound reflections from tissues of different density within an organ. Internal echoes may arise from, for example, gallstones within the gallbladder or debris within an abscess. Posttest: :‫االختبار البعدي‬ Define the following ultrasound terms? 1. Hypoechoic 2. Hyperechoic 3. Internal echoes 4. Acoustic enhancement 5. Acoustic 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 ‫المرحلة‪ :‬الرابعة‬ ‫العنوان‪:‬‬ ‫‪Title:‬‬ ‫‪Normal and abnormal liver in ultrasound‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ Introduction: :‫المقدمة‬ While using Ultrasound in the screening of high risk patients for liver diseases, there are some important signs to look at to perform both a morphological and a functional assessment. These signs include Liver size, Liver surface appearance or texture (e.g. for assessment of a potential Fatty Liver infiltration). Ultrasound can also spot potential Liver lesions deserving a second level of diagnosis. Last, Ultrasound are key to check the patency of the hepatic and portal veins. Indications • Enlarged liver/hepatomegaly. • Suspected liver abscess. • Jaundice. • Abdominal trauma. • Ascites. • Suspected metastases in liver. • Suspected liver mass. • Right upper abdominal pain. • Screening for endemic echinococcosis. Pretest: What is the ultrasound appearance of normal liver? :‫االختبار القبلي‬ Scientific Content: :‫المحتوى العلمي‬ Normal liver The normal liver parenchyma appears homogeneous, interrupted by the portal vein and its branches which are seen as linear tubular structures with reflective walls. The thinner hepatic veins are non-reflective. In a normal liver, it should be possible to follow the hepatic veins to their confluence with the inferior vena cava. Hepatic veins can be made to dilate when the patient performs the Valsalva manoeuvre (forced expiration against a closed mouth and nose). The vena cava may be seen in the liver and may vary with respiration. The aorta may be identified as a pulsatile tubular structure behind and medial to the liver (Fig-1 and 2). As well as the right and left lobes of the liver, it is also important to recognize the caudate lobe, limited posteriorly by the inferior vena cava. The gallbladder and the right kidney must also be identified. The gallbladder will appear on a longitudinal scan as an echo-free, pear- shaped structure. The echogenicity of the normal liver parenchyma lies midway between that of the pancreas (more echogenic) and the spleen (less echogenic). Fig-1: Oblique (upper) and transverse (lower) scans of the liver showing the portal and hepatic veins and the inferior vena cava. Fig-2: Two transverse scans at slightly different angles showing the inferior vena cava, the hepatic veins and the bright (echogenic) walls of the portal veins. Abnormal liver Enlarged liver/hepatomegaly: homogeneous pattern When the liver is enlarged but has a normal diffuse homogeneous echo pattern, consider the following: • Congestive cardiac failure. The hepatic veins will be dilated. The inferior vena cava does not vary on respiration. Look for a pleural effusion above the diaphragm • Acute hepatitis. There are no characteristic sonographic changes, but the liver may be enlarged and tender. • Tropical hepatomegaly. The only significant finding is liver enlargement, usually associated with splenomegaly. • Schistosomiasis. The liver can be either sonographically normal or enlarged, with thickening of the portal vein and the main branches, which become highly echogenic, especially around the porta hepatis. Enlarged liver: non-homogeneous pattern - Without discrete masses. when there is increased echogenicity in the liver parenchyma, with loss or the highly reflective edges or the peripheral portal veins, cirrhosis, chronic hepatitis or a fatty liver should be suspected. - With multiple echogenic masses. Multiple masses of various Sizes, shapes and echo textures, producing a non-homogeneous echo pattern throughout the liver, are consistent with. • Macronodular cirrhosis. The liver is enlarged with echogenic masses of various sizes but with normal intervening tissue. The normal vascular anatomy is distorted. • Multiple abscesses. These are usually ill defined, with strong back wall echoes and internal echoes. • Multiple metastases. These may be hyperechogenic or hypo echogenic and well circumscribed or ill defined, or both.Metastases are often more numerous and more variable in size than abscesses: multinodular hepatocarcinoma can resemble metastases(Fig-3). Fig-3: Transverse scan: multiple well-defined metastases in the liver • Lymphoma. This may be considered when there are multiple hypoechogenicm masses in the liver, usually with irregular outlines and without associated acoustic enhancement. It is not possible to distinguish between lymphoma and metastases by ultrasound. • Haematomas. These are often irregular in outline, with acoustic enhancement. However, when blood has clotted, the haematomas may be hyperechogenic. It is important to obtain a clinical history of either trauma or anticoagulant medication. Small liver/shrunken liver A diffusely increased echogenicity and distorted portal and hepatic veins in a shrunken liver are usually due to micronodular cirrhosis. This is often associated with portal hypertension, splenomegaly, ascites, dilated splenic veins and multiple varices. If the lumen of portal vein is filled with echoes. there may be thrombosis. which can extend into the splenic and mesenteric veins. Some patients with this type of cirrhosis may have a liver that appears normal in the early stages. Posttest: :‫االختبار البعدي‬ What are the sonographic features of multiple echogenic masses in the liver? 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 ‫المرحلة‪ :‬الرابعة‬ ‫العنوان‪:‬‬ ‫‪Title:‬‬ ‫‪Cystic lesions in normal or large liver‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ :‫المقدمة‬ Introduction: Simple hepatic cysts are common benign liver lesions and have no malignant potential. They can be diagnosed with ultrasound, CT, or MRI. Simple hepatic cysts are one of the commonest liver lesions, occurring in ~5% (range 2-7%) of the population. There may be a slight female predilection. Hepatic cysts are typically discovered incidentally and are almost always asymptomatic. They can demonstrate slow growth over time, although rapid size increase may be caused by internal hemorrhage. Simple hepatic cysts may be isolated or multiple and may vary from a few millimeters to several centimeters in diameter. Simple hepatic cysts are benign developmental lesions that do not communicate with the biliary tree 2. The current theory regarding the origin of true hepatic cysts is that they originate from hamartomatous tissue. On histopathological analysis, true hepatic cysts contain serous fluid and are lined by a nearly imperceptible wall consisting of cuboidal epithelium, identical to that of bile ducts, and a thin underlying rim of fibrous stroma. While they can occur anywhere in the liver, there may be a greater predilection towards the right lobe of the liver. Pretest: What are the types of cystic lesions in the liver? :‫االختبار القبلي‬ Scientific Content: :‫المحتوى العلمي‬ Cystic lesions in normal or large liver • Well defined solitary cyst. A well rounded, echo-free mass with acoustic enhancement, usually less than 3 cm in diameter, and often a chance finding without symptoms, is likely to be a solitary simple congenital cyst. A small hydatid cyst must also be excluded and cannot always be differentiated sonographically (Fig-4). It is usually an incidental finding during the ultrasound scan. Frequently, small cysts are peripheral and therefore more likely to be missed on ultrasound than CT. Fig-4: Transverse scan: a simple hepatic cyst with a sharp outline and acoustic enhancement. • Solitary cyst with a rough irregular outline. See liver abscess. • Multiple cystic lesions. Multiple spherical cystic masses of varying sizes, completely echo-free with a sharp outline and posterior acoustic enhancement, may indicate congenital polycystic disease. Search for cysts in the kidney, pancreas and spleen; congenital cystic disease can be very difficult to differentiate from hydatid disease. • Complex cyst. Haemorrhage or infection of any cyst may result in internal echoes and resemble an abscess or necrotic tumour. • Some cysts may contain a thin septum, which is not a significant finding. However, cysts which contain solid nodules or thickened walls should be viewed with suspicion. • Echinococcal cyst. Hydatid disease can present a broad spectrum of sonographic features. • Ultrasound has a >90% sensitivity for the diagnosis of hydatid cyst, based on its sonographic features, which can be confirmed on antibody titres to hydatid antigen using counter immunoelecrophoresis. • At ultrasound hydatid cysts may be single or multiple and have a number of described appearances, largely dependent upon the stage of the disease as follows: ✓ Initially they can appear as simple cysts. Distinguishing features include a double linear echo to the cyst wall, fine echogenic debris (hydatid sand) within the cyst, which can be accentuated by moving the patient and there may be evidence of cyst wall calcification. Ultrasound is the most sensitive modality for the detection of membranes, septa and hydatid sand. ✓ Multivesicular cysts represent the presence of multiple daughter cysts, sometimes separated by echogenic matrix material. ✓ Calcification of the cyst wall can be partial or complete and dense, with the latter producing a strong acoustic shadow. Partial calcification does not always indicate death of the cyst. • The main complication of hepatic hydatid is cyst rupture (50– 90%). • The cyst becomes increasingly echogenic and layering of echogenic hydatid sand or linear membranous material has been described in the dilated biliary system, in up to 77% of cases (See Table 1, cystic focal liver lesionsdifferential diagnosis). • Before needle aspiration of an apparently solitary cyst , scan the whole abdomen and x-ray the chest. Hydatid cysts are usually multiple and may be dangerous to aspirate. Table 1: cystic focal liver lesions-differential diagnosis Posttest: :‫االختبار البعدي‬ What are the sonographic features of cystic lesions seen in the liver? References: :‫المصادر‬ • Palmer, Philip ES, ed. Manual of diagnostic ultrasound. World Health Organization, 2002. • Paul L. Allan, Grant M. Baxter, Michael J.Weston. Clinical Ultrasound. Volume one, 3rd Edition, 2011. ‫الجامعة التقنية الوسطى‬ ‫كلية التقنيات الصحية والطبية‪ /‬بغداد‬ ‫قسم ‪ :‬تقنيات االشعة‬ ‫المادة‪ :‬فحوصات الموجات فوق الصوتية‬ ‫المرحلة‪ :‬الرابعة‬ ‫العنوان‪:‬‬ ‫‪Title:‬‬ ‫‪Differential diagnosis of liver masses, Trauma of the liver‬‬ ‫اسم المحاضر‪:‬‬ ‫‪Name of the instructor:‬‬ ‫م‪ .‬عبدالستار عارف خماس‬ ‫الفئة المستهدفة‪:‬‬ ‫طلبة المرحلة الرابعة‬ ‫قسم تقنيات االشعة‬ ‫‪Target population:‬‬ Introduction: :‫المقدمة‬ Because abdominal ultrasonography is both noninvasive and inexpensive, currently, it is the imaging method used most frequently to screen for liver tumors. Ultrasonography can effectively identify a liver mass of 5 mm and is valuable to differentiate cystic from solid lesions. Liver cirrhosis results from hepatocellular necrosis, fibrosis, and regeneration. Because regenerative nodules are common in liver cirrhosis, the most important clinical problem is to distinguish a regenerative nodule from a small HCC. On liver ultrasonography, regenerative nodules are small, hypoechoic nodules. Liver lesions represent a heterogeneous group of pathology ranging from solitary benign lesions to multiple metastases from a variety of primary tumors. Liver lesions may be infiltrative or have mass-effect, be solitary or multiple, benign or malignant. Assessment of liver lesions takes into consideration their appearance and vascularity on a variety of imaging modalities: • cystic liver lesions • hypervascular liver lesions • liver tumors The differential diagnosis for pediatric liver lesions is different to that for an adult. Pretest: How to differentiate the liver lesions by ultrasound? :‫االختبار القبلي‬ Scientific Content: :‫المحتوى العلمي‬ Differential diagnosis of liver masses It may be difficult to distinguish hepatocellular carcinoma from multiple liver metastases or abscesses. Primary carcinoma usually develops a s one large dominant mass, but there may be multiple masses of various sizes and patterns, which may have a hypoechogenic rim. The centre may become necrotic and appear quite cystic, with fluid-filled cavities and thick, irregular margins. It can be very difficult to distinguish such tumours from abscesses A single solid mass in the liver Many different diseases may cause a solitary, solid mass in the liver. The differential diagnosis may be very difficult and may require biopsy. A solitary, well defined hyperechogenic mass close to the liver capsule may be a haemangioma: 75% of haemangiomas have posterior acoustic enhancement without acoustic shadowing, but when large may lose hyperechogenicity and cannot be easily differentiated from a primary malignant liver tumour. Occasionally there will be multiple haemangiomas, but they do not usually produce clinical symptoms. It can be very difficult to differentiate a hamangioma from a solitary metastasis, abscess, or hydatid cyst. A lack of clinical symptoms strongly suggests haemangioma. To confirm the diagnosis, either computerized tomography, angiography, magnetic resonance imaging or radionuclide scanning with labelled red blood cells will be necessary. A single homogeneous mass with a low-level echo around the periphery is probably a hepatoma. However, hepatomas may also present with central necrosis or as a diffuse mass, can be multiple and may also infiltrate the portal or hepatic vein.