J. K. Han

Imaging of intrahepatic and hilar cholangiocarcinoma

Intrahepatic cholangiocarcinoma arises from the bile ducts peripheral to the secondary bifurcation of the left or right hepatic duct, whereas hilar cholangiocarcinoma arises from one of the hepatic ducts and may involve the bifurcation of the common bile duct [1–6]. For the diagnosis and evaluation of the extent of intrahepatic peripheral cholangiocarcinoma, contrast-enhanced spiral computed tomography (CT) and dynamic magnetic resonance imaging (MRI) could be used. Although CT provides better anatomic detail (e.g., by depicting vascular or extrahepatic invasion) and more accurate staging [7], MRI demonstrates more conspicuous contrast enhancement, which facilitates the detection and evaluation of hepatic parenchymal changes peripheral to the tumor. However, the two modalities are equally effective in the detection and correct diagnosis of the tumor. Traditionally, tumors accompanying biliary dilatation have been evaluated with direct cholangiography (percutaneous transhepatic or endoscopic retrograde cholangiography). However, recent technologic developments have led to rapid improvement in the quality of MR cholangiography. This imaging modality is diagnostic in more than 90% of patients with malignant hilar strictures. Further, MR cholangiography with axial T1and T2-weighted imaging may allow identification, characterization, and staging of these lesions [8, 9]. In this article, we describe the imaging spectrum of intrahepatic and hilar cholangiocarcinomas.

Abdominal amyloidosis: spectrum of radiological findings.

Amyloidosis is a disease characterized by the deposition of fibrillar protein amyloid of beta-structure in organs or tissues. It is usually classified as either a primary disease or secondary to a co-existent condition, such as rheumatoid arthritis, tuberculosis, or neoplasm (particularly multiple myeloma or renal cell carcinoma). Amyloid protein deposition can be seen in a variety of organs though it occurs with higher frequency in the gastrointestinal tract, kidney, and heart. Amyloidosis can have a wide spectrum of manifestations in nearly every abdominal organ. Some of these, for example, multiple cystic submucosal masses of the stomach, amyloidosis of the gallbladder, and dirty soft tissue infiltration of the subcutaneous fat, have not yet been covered in the radiological literature. The combination of various imaging techniques and the identification of characteristic computed tomography (CT) hepatic features may help in the differentiation of amyloidosis from other infiltrative diseases; however, confirmative diagnosis can usually only be achieved by tissue biopsy.

Preoperative evaluation of Klatskin tumor: accuracy of spiral CT in determining vascular invasion as a sign of unresectability

AbstractBackground: To assess the accuracy of spiral computed tomography (CT) in predicting the resectability of Klatskin tumor as determined by vascular invasion. Methods: Twenty-one consecutive patients with Klatskin tumor who had undergone laparotomy were included in this study. The preoperative thin-section (5-mm-thick) spiral CT scans of these patients were assessed for the surgical resectability of tumor by evaluating the vascular invasion. The criterion for vascular invasion indicating unresectability was the tumoral invasion of the proper hepatic artery or main portal vein or simultaneous invasion of one side of the hepatic artery and the other side of the portal vein. Results: All nine patients with tumors thought to be unresectable on the basis of CT findings had tumors that were unresectable at surgery (positive predictive value, 100%). Of 12 patients with tumors thought to be resectable, six had resectable tumors (negative predictive value, 50%). Spiral CT failed to detect small hepatic metastasis (n= 1), lymph node metastasis (n= 1), extensive tumor (n= 2) and variation of bile duct (n= 2), which precluded surgical resection. Conclusion: Spiral CT is a reliable method for detecting vascular invasion and unresectable tumors. However, it has limitations in detecting variations of the bile duct or the intraductal extent of tumor.

Hepatocellular carcinoma: evaluation of therapeutic response to interventional procedures.

Surgical resection remains the principal curative treatment for hepatocellular carcinoma (HCC) [1]. However, most patients with HCC are not eligible for surgical resection at the time of diagnosis owing to the status of the patients or tumors [2, 3]. In the past decade, a variety of interventional procedures have been employed for the local control of HCC. These include transcatheter arterial chemoembolization (TACE) [4], local ablation techniques using a direct intratumoral injection of compounds such as absolute ethanol [5] or hot saline [6], and thermal ablation techniques such as microwave ablation [7] and radiofrequency (RF) ablation [8]. Precise evaluation with imaging modalities is important to determine whether the tumor is completely treated or needs additional treatment. The information provided by imaging studies is used to estimate prognosis and can modify the treatment plan. Color or power Doppler sonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and angiography have been used for that purpose [9–15]. After successful treatment, the treated lesion is devoid of vascularity on color or power Doppler US and it no longer enhances with contrast material on CT and MRI. When the tumor is not completely treated, residual viable tissue can be detected on Doppler US, CT, and MRI as focal hypervascular foci within the treated lesion [9–11, 14, 15]. For the definite assessment of therapeutic efficacy of interventional procedures, histologic examination using percutaneous needle biopsy may be needed. The procedure, however, is invasive and the specimen retrieved does not always represent the entire lesion owing to sampling errors [15]. Therefore, follow-up imaging studies have been used mostly for that purpose. In this article, we review the imaging findings of HCC treated with interventional procedures and discuss the values and pitfalls of each imaging modality in evaluating therapeutic response.

Heterotopic pancreas of the stomach: CT findings correlated with pathologic findings in six patients

AbstractBackground: The purpose of this study was to characterize the computed tomographic (CT) findings of heterotopic pancreas of the stomach. Methods: CT scans of six surgically proven cases of heterotopic pancreas of the stomach were reviewed. Three were dynamic spiral CT scans, with both arterial dominant and late phase scans. In other three, both unenhanced and contrast-enhanced scans were obtained by using conventional techniques. Particular attention was given to the enhancement of the heterotopic pancreas. Pathologic and surgical findings were correlated with CT findings. Results: The locations were in the gastric antrum in five cases and in the mid-body in one. Size ranged from 1 cm to 3 cm (mean = 2.1 cm). Three cases showed homogeneous, strong enhancement similar to the pancreas and consisted mainly of pancreatic acini with the same histologic features as the normal pancreas. Two cases showed poor enhancement and consisted mainly of ducts and hypertrophied muscle; pancreatic acini were a minor component. In one case appearing as a cystic lesion on CT, a pseudocyst was found with many ducts and some nests of pancreatic acini. Conclusions: Heterotopic pancreas of the stomach showed a diverse spectrum of CT findings. Good understanding of these CT findings may be helpful in making a correct diagnosis.

Three-dimensional spiral CT cholangiography with minimum intensity projection in patients with suspected obstructive biliary disease: comparison with percutaneous transhepatic cholangiography

AbstractBackground: To evaluate the diagnostic potential of spiral computed tomographic (CT) cholangiography with minimum intensity projection (minIP) in the diagnosis of patients with suspected biliary obstruction. Methods: Nine consecutive patients with obstructive biliary disease were enrolled in this study. Spiral CT data (3-mm slice thickness, pitch 1∼2:1) obtained 65 s after the start of contrast medium injection (150 mL Ultravist 370, 3 mL/s) were reconstructed at 1-mm intervals. Three-dimensional (3D) CT cholangiography with minIP (3D CTC) was generated with a Siemens software package. The quality of 3D CTC in its ability to demonstrate the anatomic detail, the level of obstruction, and the presence or absence of isolated hepatic segments was evaluated using percutaneous transhepatic cholangiography as a gold standard. Results: In all patients, 3D CTC demonstrated dilated intrahepatic ducts up to tertiary branches. 3D CTC correctly diagnosed the level of biliary obstruction and demonstrated isolated segments in all patients. In determining the cause of biliary obstruction, one patient with hilar cholangiocarcinoma was misdiagnosed as having biliary invasion by hepatocellular carcinoma. Conclusion: 3D CTC with minIP can determine the level and cause of biliary obstruction. 3D CTC can be obtained from regular thin-section helical CT data and may be a strong competitor against diagnostic magnetic resonance cholangiography because of its superior resolution and information on adjacent soft tissues and the duct itself.

Enhancement patterns of hepatocellular carcinomas on multiphasicmultidetector row CT: comparison with pathological differentiation

OBJECTIVE The objective of this study was to determine the incidence of typical and atypical enhancement patterns of hepatocellular carcinomas (HCCs) on multiphasic multidetector row CT (MDCT) and to correlate the enhancement patterns and morphological image findings of HCC with the degree of tumour differentiation. METHODS MDCT images of 217 patients with 243 surgically proven HCCs were evaluated through consensus reading by two radiologists. Our MDCT protocol was composed of precontrast, arterial, portal and delayed phases. The reviewers analysed the CT images for degree of attenuation; relative timing of washout; presence of dysmorphic intratumoral vessels, aneurysms and necrosis; tumour size; tumour margin; presence of pseudocapsule; intratumoral heterogeneity; and determined enhancement pattern. The imaging features were correlated with tumour differentiation using Fishers exact test or the χ(2) test. RESULTS Among 243 HCCs, 137 (56.4%) showed the typical enhancement pattern of HCC, which is arterial enhancement and washout on portal or equilibrium phase images. In the arterial phase, 190 of 243 (78.2%) HCCs showed hypervascularity, with approximately three quarters of poorly differentiated (PD) (34 of 45, 75.6%) and moderately differentiated (MD) HCCs (92 of 123, 74.8%) showing washout during the portal or delayed phases, vs only 50% of well-differentiated (WD) HCCs (11 of 22; p<0.048). The presence of intratumoral vessels and aneurysms, tumour necrosis, attenuation of precontrast, the relative timing of washout, intratumoral attenuation heterogeneity, tumour margin and tumour size were correlated with the pathological differentiation of HCCs (p<0.05). CONCLUSION A typical enhancement of HCCs on MDCT was not unusual (43.6%) and WD and PD HCCs account for most of the atypical enhancement patterns. Early washout favoured MD and PD HCCs rather than WD HCCs, whereas in our study the presence of intratumoral aneurysm was a highly specific finding for PD HCC.

Focal eosinophilic infiltration in the liver: radiologic findings and clinical course.

AbstractBackground: We investigated the radiologic findings and clinical course of focal eosinophilic infiltration in the liver. Methods: We retrospectively reviewed computed tomographic (CT) and sonographic scans in 20 patients (18 male, two female; mean age, 50 years) with pathologically or clinically proven focal eosinophilic infiltration in the liver by two experienced radiologists in our institute from August 1995 to June 1999. We also correlated radiologic findings with peripheral eosinophil count. Radiologic and clinical findings during the follow-up (range, 2–49 months; mean, 19.5 months) also were analyzed. Results: Clinical symptoms and signs included abdominal pain (n = 4), easy fatigability (n = 3), weight loss (n = 1), and peripheral eosinophilia (n = 19). Twelve patients were asymptomatic. On sonographic examinations, all lesions were seen as focal, low echoic nodules. On CT, the lesions appeared isoattenuated or low attenuated in the arterial phase and low attenuated in the portal phase, except one case that showed high attenuation in the arterial phase. The margins of most lesions appeared poorly defined. Lesions were single (n = 9) and multiple: two to five (n = 6), six to 10 (n = 3), and more than 10 (n = 2). Each lesion was smaller than 2 cm; only one was 4 cm in diameter. The distribution of the lesion was subcapsular in 14 patients and central in five. Diffuse dissemination was observed in one. Eosinophil-associated abnormality was not present in other abdominal organ in all cases. The peripheral eosinophil count correlated closely with the number but not with the size of lesions. Sixteen patients who had follow-up images showed complete (n = 14) or partial regression of the lesions with a decrease in size (n = 1) or number (n = 1) after 2–22 months (mean, 6.4 months). Conclusion: Focal eosinophilic infiltration in the liver had somewhat characteristic radiologic findings on sonography and CT. In the correct clinical context of peripheral eosinophilia and self-limited course, these radiologic findings may be helpful in differentiating this condition from other focal hepatic lesions.

Hepatic Hemangioma: Contrast-Enhancement Pattern during the Arterial and Portal Venous Phases of Spiral CT

The objective of the present study was to evaluate contrast-enhancement patterns of hepatic hemangioma according to size during hepatic arterial (30-s delay) and portal venous (65-s delay) phases of spiral computed tomography (CT). During a 10-month-period, 73 patients with 118 hemangiomas underwent two-phase spiral CT examination. The enhancement patterns of tumors were divided into four types based on the attenuation of surrounding liver parenchyma: peripherally nodular high, uniform high, iso, and low. The diameter of the tumors were <10 mm (n= 39), 11–20 mm (n= 33), and >21 mm (n= 46). Overall, the most common enhancement patterns of hemangioma were peripherally nodular high (66/118, 55.9%) during the arterial and portal venous phases. The second most common contrast-enhancement patterns of hemangioma were uniform high (15/118, 12.7%) during the arterial and portal venous phases. In tumors smaller than 20 mm, 11 (9.3%) had low-low attenuation and two (1.7%) had iso-low attenuation during the arterial and portal venous phases, respectively. In conclusion, at two-phase spiral CT, the most common contrast-enhancement patterns of hemangioma are peripherally nodular high and/or uniform high during the arterial and portal venous phases. However, hemangiomas smaller than 2 cm may have atypical enhancing patterns including low and iso-attenuation.

Primary angiosarcoma of the spleen. CT and MR imaging.

The CT and MR findings in 2 patients with surgically proven splenic angiosarcoma are presented. Two distinctive radiologic and pathologic patterns were observed: total tumor replacement of the spleen with preservation of normal contour or multiple nodular masses in the spleen. The various findings on CT and MR imaging reflected the hemorrhagic nature of the lesions with increased iron content. MR imaging appeared to be superior to CT in demonstrating these features. In the case of focal lesions, radiologic differentiation from lymphoma or metastasis was impossible.