Diseases of the liver

Diseases of the liver

Diseases of the Liver Kenneth J. W. Taylor and Tina S. Richman U LTRASOUND permits the diagnosis of liver tumors with a sensitivity of approximately...

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Diseases of the Liver Kenneth J. W. Taylor and Tina S. Richman

U

LTRASOUND permits the diagnosis of liver tumors with a sensitivity of approximately 90%.’ Equally important from the viewpoint of patient management, ultrasound makes possible the reliable exclusion of a liver mass with a specificity of 96%.’ However, benign tumors cannot be differentiated from malignant ones by ultrasound. Hemangioma and focal nodular hyperplasia are notable exceptions, since they have specific characteristics that suggest the diagnosis. Needle biopsy under ultrasound guidance may provide both histologic and cytologic diagnosis in a most expeditious way. Major disadvantages of ultrasound are the lack of standardization in equipment, the wide variation in expertise, and the fact that numerous sections must be made to examine the liver adequately. Recent improvements in real time technology have facilitated the acquisition of technically optimal scans, overcoming some of these limitations. A variety of modalities are currently available for imaging the liver, and any of these can detect liver lesions greater than 2 cm in diameter.*” However, for reasons of efficiency and economy, we advocate the use of ultrasonically guided biopsy of a hepatic mass in preference to the other imaging procedures. SEGMENTAL

ANATOMY

The liver is highly variable in size and shape. A common normal variant is the small left lobe; another is the large right lobe extending into the iliac fossa (Riedel lobe). Attempts have been made to quantify liver size by measuring the longitudinal span of the liver in the midclavicular line.4 A span of 13 cm was found to be normal in 98% of patients, whereas 15.5 cm or greater proved abnormal in 75%. Using these measureFrom the Yale University School of Medicine. Department of Diagnostic Radiology, New Haven, Conn. 06510. Kenneth J. W. Taylor: Professor of Diagnostic Radiology, Yale University School of Medicine; Tina S. Richman: Assistant Professor of Diagnosiic Radiology, Yale University School of Medicine. Address reprint requests to Dr. Kenneth J. W. Taylor, Dept. of Diagnostic Radiology, Yale University School of Medicine, 333 Cedar Avenue, New Haven. CT 06510. 0 I983 by Crune & Stratton, Inc. 0037-198X/83/18024008$01.00/0 94

ments, a sonographic estimate of liver enlargement can be made with an overall accuracy of 87%. However, a major limitation of this measurement exists in that 25% of the population falls between 13 cm and 15.5 cm. Since an estimate of liver size is of so little value as a diagnostic indicator, focal areas of abnormal echogenicity are sought. The vessels supplying the liver form the landmarks that delineate the segmental anatomy. The hepatic veins lie between the lobes and between segments. These vessels can easily be traced by real time ultrasound, making this modality superior to both CT and angiography in defining the exact anatomic position of a tumor. The main lobar fissure, which contains the middle hepatic vein, divides the embryologic left and right lobes of the liver. This fissure can be clearly seen on transverse scans as an echogenic line passing from the inferior vena cava to the gallbladder fossa (Fig. 1A).’ On the longitudinal scan, the fissure is seen as a bright echogenic line extending from the right portal vein to the gallbladder fossa. It serves as a valuable landmark for the gallbladder (Fig. 1B). The right lobe is subdivided into anterior and posterior segments by a branch of the right hepatic vein. Each segment is supplied by its respective branch of the right portal vein. The left lobe of the liver is comprised of medial and lateral segments. The ligamenturn teres lies in the caudal third of the left intersegmental fissure. The middle third of this fissure contains the left portal vein, while the cranial third contains the left hepatic vein. The caudate lobe of the liver is separate from the left and right lobes, and possesses its own vascular supply. The lobe is limited posteriorly by the inferior vena cava (Fig. 2). The fissure for the ligamenturn venosum separates the caudate lobe from the left lobe of the liver anteriorly and superiorly. Shadowing from fat in the fissure may cause the caudate lobe to appear hypoechoic, simulating a tumor.* However, the straight borders identify this as an obvious artifact. SONOGRAPHIC APPEARANCES OF LIVER METASTASES

Metastases are the most common tumors of the liver. The sonographic appearance varies and

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Fig. 1. Main lobar fissure (arrow) dividing left and right lobes of the liver. lobar fissure extends from the right portal vein to the gallbladder fossa (G).

is similar to that seen in benign tumors and inflammatory masses. Differentiation from a simple cyst of the liver can be reliably made, and this is valuable in the cancer patient referred because of a positive liver-spleen scan. The combination of an echo-free cavity with good through transmission is virtually diagnostic of a simple cyst (Fig. 3). Such cysts are common, occurring

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in approximately I’% of the population. Cysts may be partially or completely septated and are usually not associated with polycystic disease or metastases. While a necrotic metastasis may become cystic, it almost invariably shows a solid component and debris. If a necrotic metastasis is suspected, needle aspiration may be performed, but in practice this is rarely necessary.

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Fig. 5. carcinoma Fig. 3. Simple cyst. Note the smooth walls, absence of echoes within the cavity (C) except for the reverberation artifact superficially, and the excellent through transmission.

In our experience, 37.5% of liver metastases were hypoechoic (Fig. 4) 27% were purely echogenic lesions (Fig. 5), and 37.5% were of mixed echogenicity.4 In our series, 54% of the echogenic metastases were of colonic origin. Hillman et al5 reported that 62% of liver metastases in their series were echogenic and 61% of these were of colonic origin. Scheible et al6 found 37% of liver metastases echogenic, of which 70% were of colonic origin. The incidence of liver metas-

Fig. 4. Small hypoechoic liver lesion (arrow) approximately 1 cm in diameter, on a transverse scan. This was a metastasis from a carcinoma of the ovary.

Small echogenic liver metastasis of the colon. Longitudinal scan.

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tases of colonic origin in a large postmortem study was only 16%. Thus there is a strong correlation between colon carcinoma and echogenie metastases.’ In our series, 44% of hypoechoic metastatic liver tumors were lymphomas (Fig. 6). PRIMARY TUMORS OF THE LIVER Malignant

Tumors

Hepatoma We have found hepatomas to be highly variable in appearance; a complete spectrum has been noted, from cystic to purely echogenic lesions (Fig. 7). Dubbins et al8 reported 32 patients with hepatoma and found the lesion to be hypoechoic in 47%, echogenic in 23%, and of mixed echogenicity in 17%. Diffuse neoplastic infiltration of the liver occurred in the remaining 13%. The lesion was detected on ultrasound scan in 31 of 32 tumors, a sensitivity of 97%. Broderick et al9 reported detection with ultrasound in 17 of 19 hepatomas, a sensitivity of 89%. All the hepatomas were detected as cold areas on 99m technetium sulfur colloid scintigraphy and showed uptake of “gallium citrate. They concluded that the combination of these two radionuclide examinations was more sensitive than ultrasound for the detection of hepatoma. However, uptake of 67gallium will occur in up to 50% of liver metastases and virtually all inflammatory lesions, so that the diagnosis of hepatoma cannot be made by radionuclide studies or ultrasonography.

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In the clinical setting of cirrhosis, however, ultrasound in conjunction with a liver-spleen scan and a “gallium scan allows a more specitic diagnosis. A focal cold area seen on the liver scan may be due to a regenerating nodule, an area of dense fibrosis, or a hepatoma. Uptake of “‘gallium in the lesion is highly suggestive of hepatoma. In contrast, a regenerating nodule seldom appears as a focal defect on ultrasonography. In 22 alcoholics we noted 4 focal lesions on ultrasound and all of them proved to be hepatoma on biopsy.‘” C’holangiocarcinoma

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Klatskin” reported I3 patients with cholangiocarcinoma who displayed distinctive clinical and pathologic features. These tumors tend to be small and have a predilection for the confluence of the hepatic ducts. Thus they tend to present early with jaundice. Initially only one hepatic duct may be obstructed, resulting in unilateral “pre-icteric” biliary dilatation.” Such an appearance is seen in Fig. 8. An echogenic mass in the region of the porta hepatis associated with biliary dilatation is highly suggestive of cholangiocarcinoma. Without decompression of the obstructed biliary tree, death usually occurs within a few months. However, the tumor is of

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low grade malignancy, so that if the biliary tree is drained survival of 3 to 4 yr is likely. Response to Therapy Sequential ultrasound studies allow easy assessment of tumor response to therapy. The tumor may increase in size, decrease, or remain constant.13 The tumor may undergo central necrosis. Benign Tumors

Hemangioma A focal mass in the liver is not infrequent, especially in young females. It is usually found incidentally in a woman referred with possible gallbladder disease. The finding creates a problem in management. The lesion usually proves to be a hemangioma, which has a reported autopsy incidence in the general population of 1% to 7%. Hemangiomas are usually echogenic although they may be hypoechoic, a spectrum similar to that of other benign and malignant tumors (Fig. 9). In a young patient without evidence of a primary tumor and with normal liver function tests, the diagnosis of a hemangioma may be assumed and a follow-up ultrasound examination performed in 3 mo. However, in an older patient with an incidental echogenic liver mass, consideration should be given to performing a barium enema to exclude a primary colonic carcinoma. A CT scan should be suggested if the mass is large. A specific appearance has been described as characteristic of a hemangioma. This includes intense contrast-enhanced vascularity around the periphery of the lesion, with delayed opacification of the center of the mass.14 While this appearance is typical of a hemangioma greater than 4 cm in diameter, most of the lesions we see are smaller than this. A cutting needle biopsy must be avoided at all cost, although we are aware of many skinny needle biopsies performed on hemangiomas without complications. Focal Nodular Hyperplasia Focal nodular hyperplasia (FNH) is a benign innocuous lesion of uncertain pathogenesis. It is composed of hepatocytes and bile vessels, and contains Kupffer cells. Thus it may take up technetium sulfur colloid (Fig. 10). A simple stellate scar demonstrated by CT15 or ultra-

Fig. 9. Hemangioma in a Cmo-old male. (A) Hypoechoic mass (arrows) in the right lobe of the liver. IB) The liver-spleen scan shows no uptake of technetium sulfur colloid by the mass (arrows).

soundI may facilitate the diagnosis. The incidence is around 20 per 100,000 population, Liver Cell Adenoma Liver cell adenoma (LCA) is often confused with FNH. It is a true benign neoplasm composed of hepatocytes. It does not contain Kupffer cells and therefore does not show technetium sulfur colloid uptake (Fig. 11). It is a very rare tumor, with an incidence of only 4 per 100,000 autopsies between 1918 and 1954.” The incidence of LCA has increased with the widespread use of oral contraceptives. There is evidence that

DISEASES

OF THE LIVER

Fig. 10. Focal nodular hyperplasia. (A) Longitudinal liver scan shows a hypoechoic lesion extending from the lower border of the liver (arrows). (B) Anterior view of liver scintigram demonstrates normal uptake of sulfur colloid in the mass farrowsl. This combination of a focal mass on ultrasound, which displays uptake of sulfur colloid is virtually diagnostic of focal nodular hyperplasia. Kourtesy of Dr. Alan Richman of the Department of Radiology, Norwalk Hospital, Norwalk, Corm.)

the risk of developing LCA increases with the duration of oral contraceptive use.” On the contrary, there is no firm evidence that FNH is related to oral contraceptive use. Rupture and hemoperitoneum often result from LCA, so it should be surgically excised, whereas FNH should be managed conservatively. Ultrasound is of no value in differentiating hemangioma, FNH, and LCA. Although most commonly echogenic, these entities may be hypoechoic, especially when there has been hemorrhage.” In practice, it is important to try to avoid overinvestigation, cutting needle biopsy, or surgical excision of an asymptomatic hemangioma. The incidence of hemangioma is approximately 40 times that of L.CA and FNH combined. The

possibility of LCA should be considered in a patient with oral contraceptive exposure, with a large liver mass, or with evidence of hemoperitoneum. These patients should undergo a liverspleen scan to exclude FNH, since about 50% of FNH take up technetium sulfur colloid.‘” The combination of a mass on ultrasound or CT with normal uptake of sulfur colloid appears to be virtually diagnostic of FNH. Other Benign Masses An abscess may be indistinguishable from a necrotic tumor, while cholangitis may give rise to a focal echogenic mass. When taken in clinical context, confusion is less likely, although occasionally the patient with a tumor presents with

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Fig. 11. Liver cell adenoma in a woman on birth demonstrates a complex pedunculated mass (arrows). in the region of the mass (arrows).

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control pills. (A) Longitudinal scan through the right lobe of the liver (BI The liver-spleen scan shows no uptake of technetium sulfur colloid

fever and leukocytosis. Early diagnostic aspiration is the most economic means of differentiating these conditions, and results in early histologic and bacteriologic diagnosis. Finally, the entity of fatty infiltration should be considered. Although usually considered to be diffuse in distribution, focal fatty infiltration may occur. This appears as an echogenic mass on

sonography, indistinguishable from a metastasis. Differentiation is easily achieved by CT scanning, which displays a characteristic attenuation number (Fig. 12).*’ ULTRASONICALLY

GUIDED BIOPSY

A blind liver biopsy is generally performed with a cutting needle through the right lobe of

Fig. 12. Focal fatty infiltration. (A) Longitudinal ultrasound scan shows an echogenic mass (Ml in the right lobe of the liver. (B) CT scan is diagnostic of a fatty mass (MI. The errows in (A) and (Bl delineate fat in the region of the ligamentum teres. (Courtesty of Dr. Norberto Belleza, Department of Radiology, Griffin Hospital, Derby, Corm.)

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the liver. However, when there is only minimal metastatic disease or when the tumor is limited to the left lobe, blind biopsy is frequently unproductive. Guided biopsy then becomes the procedure of choice. If the gastroenterologist wishes to perform the biopsy, we provide ultrasonic guidante to an appropriate site, and mark the skin with the projection of the underlying tumor.

However, we prefer to do the biopsy ourselves, using a fine needle in preference to a cutting needle. A 22-gauge needle must be used if the needle is likely to traverse bowel. If there is no bowel intervening, a 20-gauge needle can be safely used. This needle may provide histology in addition to cytology, and is safer than a larger cutting needle.

REFERENCES I. Sullivan DC, Taylor KJW, Gottschalk A: The use of ultrasound to enhance the diagnostic utility of the equivocal liver scintigraph. Radiology 1978;128:727-732 2. Mitchell SE, Gross BH, Spitz HB: The hypoechoic caudate lobe: an ultrasonic pseudolesion. Radiology 1982;144:569%572 3. Viscomi GN, Gonzalez R, Taylor KJW: Histopathologic correlation of ultrasound appearances of liver metastases. J Clin Gastroenterol 1981;3:395-400 4. Gosink BB, Leymaster CE: Ultrasonic determination of hepatomegaly. J Clin Ultrasound 1981;9:37-41 5. Hillman BJ, Smith EH, Gammelgaard J, et al: Ultrasonographic-pathologic correlation of malignant hepatic masses. Gastrointest Rad 1979;4:361-365 6. Scheible W, Gosink BB, Leopold GR: Gray scale echographic patterns of hepatic metastatic disease. AJR 1977; I29:983-987 7. Edmondson HA. Peters RL: Neoplasms of the liver, in Schilf L, Schiff ER (eds): Diseases of the Liver (ed 5). Philadelphia, JB Lippmcott, 1982, p I IO2 8. Dubbins PA, O’Riordan D, Melia WM: Ultrasound in hepatomaxan specific diagnosis be made? Br J Radio] 198 I ;54:307Y3 1 I 9. Broderick TW, Gosink B, Menuck L. et al: Echographic and radionuclide detection of hepatoma. Radiology 1980:135:149 I51 IO Taylor KJW, Gorelick FS, Rosenfield AT, et al: Ultrasonography of alcoholic liver disease with histological correlation. Radiology 1981;141:157-I61 I I. Klatskin G: Adenocarcinoma of the hepatic duct at its bifurcation within the porta hepatis--an unusual tumor with

distinctive clinical and pathological features. Am J Med 1965;38:241-256 12. Zeman R. Taylor KJW, Burrell MI, et al: liltrasound demonstration of anicteric dilatation of the biliary tree. Radiology I980;134:689-692 13. Bernardino ME, Green B: Ultrasonographic evaluation of chemotherapeutic response in hepatic metnstases. Radiology 1979;133:437-441 14. Barnett PH, Zerhouni EA, White RI Jr. et al: Computed tomography of cavernous hemangioma of the liver. AJR 1980;134:439%447 15. Fishman EK. Farmlett E, Kadir S. et al: Computed tomography of benign hepatic tumors. .I Comp Asst Tomogr 1982:6:472-481 16. Scatarige JC, Fishman EK, Sanders RC: The sonographic “scar sign” in focal nodular hyperplasia of the liver. J Ultrasound Med 1982;1:275-278 17. Edmondson HA: Benign mesodermal Iumors, in Tumors of the Liver and lntrahepatic Bile Ducts, section 7, fast 25, AFIP, (I 13-l I5), Washington. DC. 1958 18. Rooks JB, Ory HW, lshak KG, et al: Epidemiology of hepatoceilular adenoma: the role of oral contraceptive use. JAMA 1979;242:644-648 19. Sandler MA, Petrocelli RD. Marks DS, et al: Ultrasonic features and radionuclide correlation in Iwer cell adenoma and focal nodular hyperplasia. Radiology 1980; I35:393%397 20. Scott WW Jr, Sanders RC, Siegelman SS: Irregular fatty infiltration of the liver: diagnostic dilemma\. AJR 1980; I 35:67--7 I