Intrahepatic cholangiocarcinoma: spin-echo and contrast-enhanced dynamic MR imaging

[Imaging of intrahepatic cholangiocarcinoma : Reliable diagnosis according to the new S3 guideline]

The S3 guideline on hepatocellular carcinoma has been expanded to include malignant biliary carcinoma (synonym cholangiocarcinoma [CCA]). Magnetic resonance imaging (MRI) with additional magnetic resonance cholangiopancreatography (MRCP) is the imaging modality of choice to evaluate local findings. Use of gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-based contrast agent increases its diagnostic value. Histologic confirmation is always required when diagnosing intrahepatic CCA (iCCA) because using imaging alone there is a risk of confusion with HCC subtypes.

The Clinical Management of Cholangiocarcinoma in the United States and Europe: A Comprehensive and Evidence-Based Comparison of Guidelines

BACKGROUND

The incidence of cholangiocarcinoma has doubled over the last 15 years with a similar rise in mortality, which provides the impetus for standardization of evidence-based care through the establishment of guidelines.

METHODS

We compared available guidelines on the clinical management of cholangiocarcinoma in the United States and Europe, which included the National Comprehensive Cancer Network (NCCN), European Society for Medical Oncology (ESMO), British Society of Gastroenterology (BSG) and the International Liver Cancer Association (ILCA) guidelines.

RESULTS

There is discordance in the recommendation for biopsy in patients with potentially resectable cholangiocarcinoma and in the recommendation for use of fluorodeoxyglucose positron emission tomography scans. Similarly, the recommendation for preoperative biliary drainage for extrahepatic and perihilar cholangiocarcinoma in the setting of jaundice is inconsistent across all four guidelines. The BILCAP (capecitabine) and ABC-02 trials (gemcitabine with cisplatin) have provided the strongest evidence for systemic therapy in the adjuvant and palliative settings, respectively, but all guidelines have refrained from setting them as standard of care, given heterogeneity in the study cohorts and ABC-02's negative intention-to-treat results.

CONCLUSIONS

Future progress in enhancing survivorship of patients with cholangiocarcinoma would likely entail improvements in diagnostic biomarkers and novel systemic therapies. Based on recent results from studies of targeted therapy, future iterations of the guidelines will likely incorporate molecular profiling.

[Radiological diagnostic workup of liver tumors]

The imaging of focal liver lesions is a common task in daily radiological routine. The objectives of diagnostic imaging are, in addition to lesion detection, the characterization of the lesion as well as the follow-up assessment after surgical or local treatment or under systemic therapy. This article presents the typical morphologies observed in computed tomography and magnetic resonance imaging of hepatocellular carcinomas and intrahepatic cholangiocarcinomas as the most important representatives of primary malignant liver tumors and juxtaposes them with benign primary liver lesions such as adenoma and focal nodular hyperplasia (FNH). In addition, relevant technical aspects of imaging are briefly summarized. Finally, the main and additional criteria of the Liver Imaging Reporting and Data System (LI-RADS®) classification, which are becoming increasingly established clinically for the evaluation of liver lesions in the cirrhotic liver, are presented.

Intratumoral artery on contrast-enhanced computed tomography imaging: differentiating intrahepatic cholangiocarcinoma from poorly differentiated hepatocellular carcinoma

AIM

Differentiating intrahepatic cholangiocarcinoma (ICC) from poorly differentiated hepatocellular carcinoma (p-HCC) is often difficult, but it is important for providing appropriate treatments. The purpose of this study was to examine the features differentiating ICC from p-HCC on contrast-enhanced dynamic-computed tomography (CT).

METHODS

This study examined 42 patients with pathologically confirmed ICC (n = 19) or p-HCC (n = 23) for which contrast-enhanced dynamic CT data were available. CT images were analyzed for enhancement patterns during the arterial phase, washout pattern, delayed enhancement, satellite nodules, capsular retraction, lesion shape, and presence of an intratumoral hepatic artery, intratumoral hepatic vein, intratumoral portal vein, and bile duct dilation around the tumor, portal vein tumor thrombus, lobar atrophy, or lymphadenopathy.

RESULTS

Univariate analysis revealed the presence of rim enhancement (p = 0.037), lobulated shape (p = 0.004), intratumoral artery (p < 0.001), and bile duct dilation (p = 0.006) as parameters significantly favoring ICC, while a washout pattern significantly favored p-HCC (p < 0.001). Multivariate analysis revealed intratumoral artery as a significant, independent variable predictive of ICC (p = 0.037), and 15 ICCs (78.9%) showed this feature. Washout pattern was a significant, independent variable favoring p-HCC (p = 0.049), with 15 p-HCCs (65.2%) showing this feature.

CONCLUSION

The presence of an intratumoral artery in the arterial phase on contrast-enhanced dynamic CT was a predictable finding for ICC, and the presence of a washout pattern was a predictable finding for p-HCC, differentiating between ICC and p-HCC.

Histopathological characteristics of hypervascular cholangiocellular carcinoma as an early stage of cholangiocellular carcinoma

AIM

Prognosis of hypervascular cholangiocellular carcinoma (h-CCC) is reportedly better than that of ordinary hypovascular CCC (o-CCC). The aim of this study is to clarify the histopathological characteristics of h-CCC.

METHODS

On the basis of the findings in the arterial phase of contrast-enhanced computed tomography, 16 cases of mass-forming-type CCC were divided into two groups (h-CCC, n = 8; o-CCC, n = 8). Areas of high (Area H-a) and low (Area H-b) attenuation in h-CCC cases and areas of low attenuation in o-CCC cases (Area O) were delineated. These areas were then evaluated histopathologically to determine the proportion of tumor cells, fibrous stroma, arterial vessel density, and immunohistochemical expression of Vascular endothelial growth factor; angiopoietin-2; cytokeratin 7, CK19, SOX9 and SOX17 genes; epithelial cell adhesion molecule; and the Bmi-1, Ki-67, epithelial membrane antigen and polyclonal carcinoembryonic antigen.

RESULTS

The areal ratio of tumor cells decreased and that of fibrous stroma increased in the following order: Area H-a, Area H-b and Area O. Values for AVD and neural cell adhesion molecule positivity rate were significantly higher in Area H-a than in Areas H-b or O. Expressions of vascular endothelial growth factor and angiopoietin-2 were significantly higher in Areas H-a and H-b than in Area O. The Ki-67 labeling index increased in the following order: Area H-a, Area H-b and Area O.

CONCLUSION

A high areal ratio of tumor cells and AVD as well as a high expression of stem cells and angiogenic markers were observed in cases of h-CCC, whereas the areal ratio of fibrous stroma and malignant potential were low. These results suggest that h-CCC may represent the early stage of CCC.

Gadoxetate disodium-enhanced MRI of mass-forming intrahepatic cholangiocarcinomas: imaging-histologic correlation

OBJECTIVE

The purpose of this study was to describe the enhancement patterns of mass-forming intrahepatic cholangiocarcinomas on gadoxetate disodium-enhanced MR images using imaging-histologic correlation.

MATERIALS AND METHODS

We retrospectively evaluated the preoperative gadoxetate disodium-enhanced MR images of 19 patients with mass-forming intrahepatic cholangiocarcinomas. Two readers independently interpreted enhancement patterns on arterial (globally high, rimlike), dynamic (washout, progressive), and hepatobiliary (target, nontarget) phase images. Dynamic enhancement was categorized as washout (hypoenhancement on later phase compared with arterial phase images) or progressive (persistent or gradually increased enhancement). Tumor enhancement ratio and tumor-to-liver signal difference curves were analyzed. The enhancement patterns were correlated with the extent of stromal fibrosis within the tumors.

RESULTS

Rimlike arterial enhancement (89%, reader 1; 84%, reader 2) and a progressive dynamic pattern (89%, both readers) were predominant. Tumor enhancement ratio increased gradually from the arterial to the equilibrium phase then decreased in the hepatobiliary phase, but the tumor signal intensities were lower than liver signal intensity in all phases. The two lesions that both readers considered to have globally high arterial enhancement and a washout dynamic pattern presented with minimal or scattered stromal fibrosis. Target appearance in the hepatobiliary phase (reader 1, 42%; reader 2, 47%) was more commonly seen in tumors with central stromal fibrosis (reader 1, p = 0.025; reader 2, p = 0.001).

CONCLUSION

Mass-forming intrahepatic cholangiocarcinomas may be characterized by rimlike enhancement and a progressive dynamic pattern on gadoxetate disodium-enhanced MR images, and these features seem related to the extent of stromal fibrosis in the tumor. Furthermore, mass-forming intrahepatic cholangiocarcinomas may have a pseudowashout pattern on gadoxetate disodium-enhanced MR images because of progressive background liver enhancement. Therefore, radiologists need to be aware of this pattern as a possible pitfall.

Intrahepatic mass-forming cholangiocarcinoma: enhancement patterns on gadoxetic acid-enhanced MR images

PURPOSE

To evaluate the enhancement patterns of intrahepatic mass-forming cholangiocarcinomas (IMCCs) with emphasis on the hepatobiliary phase (HBP) of gadoxetic acid-enhanced magnetic resonance (MR) imaging.

MATERIALS AND METHODS

This retrospective study was institutional review board approved, and the requirement for informed consent was waived. Fifty patients (41 men, nine women; mean age, 62.3 years; range, 44-76 years) with IMCC underwent unenhanced and gadoxetic acid-enhanced T1- and T2-weighted MR imaging including dynamic phase and hepatobiliary phase imaging between May 2008 and December 2010. Signal intensity and enhancement patterns of lesions were compared with those of the liver parenchyma in each phase. Conspicuity and margin sharpness of lesions on dynamic phase and HBP images were rated on a 4- or 5-point scale and compared by using the Wilcoxon signed-rank test. Percentage of relative enhancement was compared among pathologic subgroups by using the unpaired Student t test.

RESULTS

On dynamic phase images, 29 of 48 (60%) lesions showed a thin peripheral rim with centripetal or gradual progression. On HBP images, 48 of 50 (96%) IMCCs were hypointense, and two of 50 (4%) were hyperintense. Subjective ratings of conspicuity and margin sharpness were significantly higher on HBP (median scores, 5 and 4, respectively) (P < .001) than on the dynamic phase (median scores, 4 and 3, respectively) images (P < .001). Additional daughter nodules were found in five patients and intrahepatic metastasis was found in one. Percentage of relative enhancement on HBP images was significantly higher in moderately differentiated (66.4% ± 42.1) than in poorly differentiated (36.84% ± 21.5) tumors (P = .039) and in patients without (59.7% ± 28.8) than in those with (24.9% ± 14.7) (P = .036) lymph node metastasis.

CONCLUSION

The most prevalent enhancement pattern on gadoxetic acid-enhanced MR images of IMCCs was a thin peripheral rim with internal heterogeneous enhancement during the dynamic phase. HBP images showed increased lesion conspicuity and better delineation of daughter nodules and intrahepatic metastasis, which may aid in the diagnosis of IMCC.

Differentiating combined hepatocellular and cholangiocarcinoma from mass-forming intrahepatic cholangiocarcinoma using gadoxetic acid-enhanced MRI

PURPOSE

To examine the differential features of combined hepatocellular and cholangiocarcinoma (HCC-CC) from mass-forming intrahepatic cholangiocarcinoma (ICC) on gadoxetic acid-enhanced MRI.

MATERIALS AND METHODS

Forty patients with pathologically proven combined HCC-CC (n = 20) and ICCs (n = 20) who had undergone gadoxetic acid-enhanced MRI were enrolled in this study. MR images were analyzed for the shape of lesions, hypo- or hyperintense areas on the T2-weighted image (T2WI), rim enhancement during early dynamic phases, and central enhancement with hypointense rim (target appearance) on the 10-min and 20-min hepatobiliary phase (HBP). The significance of these findings was determined by the χ(2) test.

RESULTS

Irregular shape and strong rim enhancement during early dynamic phases, and absence of target appearance on HBP favored combined HCC-CCs (P < 0.05). Lobulated shape, weak peripheral rim enhancement, and the presence of complete target appearance on the 10-min and 20-min HBP favored ICCs (P < 0.05). However, 10 CC-predominant type of combined HCC-CC showed complete or partial target appearance on 10-min HBP.

CONCLUSION

The shape of tumors, degree of rim enhancement during early dynamic phases, and target appearance on HBP were valuable for differentiating between combined HCC-CC and mass-forming ICC on gadoxetic acid-enhanced MRI.

Hepatobiliary MR imaging with gadolinium-based contrast agents

The advent of gadolinium-based "hepatobiliary" contrast agents offers new opportunities for diagnostic magnetic resonance imaging (MRI) and has triggered great interest for innovative imaging approaches to the liver and bile ducts. In this review article we discuss the imaging properties of the two gadolinium-based hepatobiliary contrast agents currently available in the U.S., gadobenate dimeglumine and gadoxetic acid, as well as important pharmacokinetic differences that affect their diagnostic performance. We review potential applications, protocol optimization strategies, as well as diagnostic pitfalls. A variety of illustrative case examples will be used to demonstrate the role of these agents in detection and characterization of liver lesions as well as for imaging the biliary system. Changes in MR protocols geared toward optimizing workflow and imaging quality are also discussed. It is our aim that the information provided in this article will facilitate the optimal utilization of these agents and will stimulate the reader's pursuit of new applications for future benefit.

Differentiating mass-forming intrahepatic cholangiocarcinoma from atypical hepatocellular carcinoma using gadoxetic acid-enhanced MRI

AIM

To examine the differential features of mass-forming intrahepatic cholangiocarcinoma (ICC) from atypical hypovascular hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived informed patient consent. Seventy patients with pathologically proven ICCs (35) and hypovascular atypical HCCs (35) who had undergone preoperative gadoxetic acid-enhanced MRI were enrolled in this study. Images were analysed for the shape of the lesions and presence of hyperintensity on the T1-weighted image (T1WI) and hypo- or hyperintense areas on the T2-weighted image (T2WI). In addition, images were analysed for the presence of linear hyperintensity or multifocal, tiny, hyperintense foci on T2WI and the presence of rim enhancement during early dynamic phases and a central enhancement with a hypointense rim (target appearance) on the 10 and 20 min hepatobiliary phase images. The significance of these findings was determined by the X(2) test.

RESULTS

Univariate analysis revealed that the following significant parameters favour ICC or hypovascular HCC; the presence of T2 hypo- and hyperintense areas and target appearance on the 10 min hepatobiliary phase images favour ICC, and the presence of T2 linear hyperintensity and T2 multifocal hyperintense foci favour hypovascular HCC (p < 0.05). Multivariate analysis revealed that only target appearance on the 10 min hepatobiliary phase was predictive of ICC (p = 0.002) as 30 ICCs (85.7%) showed this feature. However, the target appearance was also observed in all six scirrhous HCCs.

CONCLUSION

A target appearance on the 10 min hepatobiliary phase images is the best predictor for identifying mass-forming ICC at gadoxetic acid-enhanced MRI.

Magnetic resonance imaging of focal liver lesions: approach to imaging diagnosis

This article is a review of magnetic resonance imaging (MRI) of incidental focal liver lesions. This review provides an overview of liver MRI protocol, diffusion-weighted imaging, and contrast agents. Additionally, the most commonly encountered benign and malignant lesions are discussed with emphasis on imaging appearance and the diagnostic performance of MRI based on a review of the literature.

Mass-forming intrahepatic cholangiocarcinoma with marked enhancement on arterial-phase computed tomography reflects favorable surgical outcomes

BACKGROUND

Outcomes after hepatectomy in patients with mass-forming (MF) type intrahepatic cholangiocarcinoma (ICC) with marked enhancement within the tumor on arterial-phase computed tomography (CT) scans have not been clarified in detail.

METHODS

We retrospectively studied 140 patients with MF type ICC who underwent hepatectomy from 1989 through 2008. Surgical outcomes were compared between 25 patients with MF type ICC with marked enhancement within the tumor (hypervascular ICC) and 109 patients without enhancement within the tumor (hypovascular ICC) on arterial-phase CT scans.

RESULTS

Portal invasion and intrahepatic metastasis were significantly lower in patients with hypervascular ICC than in those with hypovascular ICC. The 5-year survival rate was significantly higher in patients with hypervascular ICC (86%) than in patients with hypovascular ICC (27%, P < 0.0001). Multivariate analysis showed hypervascular ICC on arterial-phase CT scans, normal level of cancer-associated carbohydrate antigen 19-9, absence of portal invasion, and absence of intrahepatic metastasis of ICC to be significant independent prognostic factors for overall survival in patients with MF type ICC.

CONCLUSIONS

MF type ICC with marked enhancement within the tumor on arterial CT scans showed a favorable surgical outcome due to its less invasive histopathologic characteristics in patients with MF type ICC.

Intrahepatic peripheral cholangiocarcinoma in cirrhosis patients may display a vascular pattern similar to hepatocellular carcinoma on contrast-enhanced ultrasound

The aim of this study was to describe the imaging features by contrast-enhanced ultrasound (CEUS) of intrahepatic cholangiocarcinoma (ICC) in cirrhosis patients. We registered the CEUS images of cirrhosis patients with histologically confirmed ICC. In all cases magnetic resonance imaging (MRI) was done to confirm the diagnosis and/or staging purposes. A total of 21 patients met all the criteria to be included in the study. The median nodule size was 32 mm. All nodules showed contrast enhancement at arterial phase; in 10 cases it was homogeneous and in 11 cases peripheral (rim-like). All nodules displayed washout during the venous phases; it appeared during the first 60 seconds in 10 nodules, between 60-120 seconds in five cases, and in six cases after 2 minutes. Ten nodules (five larger than 2 cm) displayed homogeneous contrast uptake followed by washout and they correspond to the specific pattern of hepatocellular carcinoma according to the American Association for the Study of Liver Diseases criteria. However, none of these lesions displayed washout on MRI.

CONCLUSION

CEUS should not be used as the sole imaging technique for conclusive hepatocellular carcinoma diagnosis and if the MRI does not display the diagnostic vascular pattern, a confirmatory biopsy is mandatory.

Comparison of diffuse hepatocellular carcinoma and intrahepatic cholangiocarcinoma using sequentially acquired gadolinium-enhanced and Resovist-enhanced MRI

PURPOSE

The purpose of this study was to compare MRI findings of diffuse hepatocellular carcinoma (D-HCC) and intrahepatic cholangiocarcinoma (IHC) to identify characteristics of each.

MATERIALS AND METHODS

We retrospectively analyzed MRI that consisted of unenhanced T1- and T2-weighted image, gadolinium (Gd)-enhanced dynamic image, and sequentially acquired Resovist-enhanced image from 29 patients with D-HCCs and 32 patients with IHC.

RESULTS

On T2-weighted imaging, D-HCCs usually appeared as poorly defined, infiltrative mildly hyperintense masses, whereas IHC appeared as well-defined, lobulated mildly hyperintense masses with areas of strong hyperintensity and hypointensity. On dynamic- and Resovist-enhanced T1-weighted MRIs, D-HCCs appeared as hypovascular and homogeneously hypointense or isointense masses with internal reticulation, whereas IHD appeared as centripetal enhancing masses with or without delayed central hyperintensity. Biliary dilatation was predominantly observed in the area adjacent to the IHC and in the intratumoral area of D-HCC. Portal venous tumor thrombus was observed in most of the D-HCC, and portal vein encasement was seen in 17 of the IHC.

CONCLUSION

D-HCC and IHC exhibited characteristics of each at T1- and T2-weighted imaging, Gd-enhanced dynamic imaging, and sequentially acquired Resovist-enhanced T1-weighted imaging.

MR and MRCP in the Evaluation of Primary Sclerosing Cholangitis

Primary sclerosing cholangitis is a progressive cholestatic disease of unknown etiology leading to cirrhosis and liver failure. Several imaging modalities have been used to study this disease, including ultrasonography, computed tomography and hepatobiliary scintigraphy, but accurate diagnosis was found to be best made with endoscopic retrograde cholangiopancreatography or direct cholangiography. However, these 2 methods are invasive and may produce serious complications. Magnetic resonance cholangiopancreatography is a noninvasive imaging technique that has become very useful for diagnosing primary sclerosing cholangitis. Contrast enhanced magnetic resonance imaging provides pertinent information of extraductal abnormalities in addition to biliary ductal changes.

Phenotypic diversity of intrahepatic and extrahepatic cholangiocarcinoma on aspiration cytology and core needle biopsy: case series and review of the literature

BACKGROUND

Cholangiocarcinoma (CC) represents approximately 10% of primary liver malignancies and can mimic metastatic adenocarcinoma.

METHODS

The authors retrospectively reviewed the cytopathology files at the University of Texas Medical Branch to identify patients who were diagnosed with intrahepatic or extrahepatic CC by aspiration cytology between 1995 and 2004. Brush cytology specimens of extrahepatic CC were excluded. All diagnoses were confirmed as CC by clinical, imaging, and histopathologic findings and by chart review.

RESULTS

Cytopathology files from 13 patients with CC diagnosed by FNA were retrieved. The male:female ratio was 5:8, and the patients ranged in age from 29 years to 74 years (mean age, 59 years). In 12 of 13 patients, aspirates were obtained by ultrasound guidance; and, in 1 patient, computed tomography guidance was used. Three patients had aspirates only, 10 patients also had core biopsies, and 1 patient had cell block preparations. The phenotypic distribution of CC according to the World Health Organization (WHO) histologic classification was 9 adenocarcinoma (intrahepatic), not otherwise specified (NOS) (69%); 2 gastric foveolar type (extrahepatic) CCs (15%); 1 intestinal type (extrahepatic) CC (8%); and 1 sarcomatous/spindle cell type (intrahepatic) CC (8%). One adenocarcinoma, NOS was well differentiated CC with bland tubular architecture, and one was pleomorphic. Ancillary histochemical and immunochemical stains were performed on 5 of 13 specimens, which included 4 core biopsies and 1 aspirate with Mucicarmine positivity (3 specimens), carcinoembryonic antigen positivity (3 specimens), and a cytokeratin 7 (CK7)-positive/CK20-negative pattern (2 specimens). The 1 sarcomatous/spindle cell type CC was chromogranin-negative and low molecular weight keratin (cell adhesion molecule 5.2)-positive, which excluded metastatic carcinoid.

CONCLUSIONS

Classification of intrahepatic and extrahepatic CC in aspiration cytology specimens was achieved in a reliable manner concordant with the WHO histologic classification. Special types of CC with bland nuclear features posed a diagnostic challenge on cytologic evaluation, particularly the well differentiated CC with tubular architecture and the gastric foveolar type CC with mucin-producing tumor cells. The addition of core biopsy and/or ancillary studies, such as histochemical and immunochemical stains, were helpful in reaching the correct diagnosis.

Clonorchiasis and cholangiocarcinoma: etiologic relationship and imaging diagnosis

Despite a gradual decrease in prevalence, clonorchiasis is still prevalent in East Asia. A large and compelling body of evidence links clonorchiasis and cholangiocarcinoma, although the mechanisms involved are not completely understood. Clonorchiasis induces biliary epithelial hyperplasia and metaplasia, and this could facilitate at least one stage of the carcinogenesis, which is promoting effect. In areas of endemic infection, more clonorchiasis cases are now diagnosed incidentally during radiological examinations such as cholangiography, ultrasonography, and computed tomography. Radiological findings are regarded as pathognomonic for clonorchiasis since they reflect the unique pathological changes of this disorder. These radiological examinations currently play important roles in the diagnosis, staging, and decision-making process involved in the treatment of cholangiocarcinoma. The morphological features and radiological findings of clonorchiasis-associated cholangiocarcinoma are essentially combinations of the findings for the two diseases. The morphological features of clonorchiasis- associated cholangiocarcinoma, observed in radiological examinations, do not differ from those of the usual cholangiocarcinoma. In patients diagnosed with or suspected to have clonorchiasis, radiological findings should be carefully scrutinized for occult cholangiocarcinoma.

Magnetic Resonance Imaging of cholangiocarcinoma

Preoperative imaging with MRI/MRA/MRCP is an accurate non-invasive method for staging cholangiocarcinoma, and determining resectability. It provides information regarding tumor size, extent of bile duct involvement, vascular patency, extrahepatic extension, nodal or distant metastases, and the presence of lobar atrophy. MRCP is better for demonstrating bile ducts distal to the stricture, although with ERCP, therapeutic intervention such as stent placement and biopsy can be performed.

Malignant liver tumors

The primary hepatic malignancies are a diverse group of neoplasms with distinctive clinical and pathologic features. Imaging of the primary hepatic malignancies continues to be challenging. Ultrasonography, CT scanning, and MR imaging play complementary roles in the evaluation of these patients. Many [figure: see text] of these neoplasms have distinctive imaging features that may permit diagnosis. In most instances, however, biopsy is required for definitive diagnosis and treatment planning.

Radiologic spectrum of cholangiocarcinoma: emphasis on unusual manifestations and differential diagnoses

Most cholangiocarcinomas are ductal adenocarcinomas that arise from both intra- and extrahepatic bile duct epithelium, and their typical growth pattern can be classified as exophytic, infiltrative, polypoid, or a combination of these. Those of unusual histologic type (eg, mucin-hypersecreting cholangiocarcinoma, squamous adenocarcinoma, biliary cystadenocarcinoma, and mucinous carcinoma) show a growth pattern different from that of the typical ones (ie, ductal). Cholangiocarcinomas frequently develop in patients with any of a variety of preexisting bile duct diseases, some of which are considered precursors of cholangiocarcinoma (eg, biliary lithiasis, clonorchiasis, recurrent pyogenic cholangitis, and primary sclerosing cholangitis). Some bulky hepatic tumors of either primary or secondary origin mimic exophytic peripheral cholangiocarcinoma. Some variants of hepatocellular carcinoma, such as sclerosing, fibrolamellar, and cholangiohepatocellular carcinoma, resemble exophytic peripheral cholangiocarcinoma, while that with intraductal growth resembles polypoid cholangiocarcinoma. Among benign bile duct diseases, tumorous conditions (eg, benign biliary tumors) may mimic polypoid cholangiocarcinoma, whereas benign stricture of various causes (eg, cholangitides, traumatic and postsurgical sequelae, chronic pancreatitis, papillary stenosis) usually mimics infiltrative cholangiocarcinoma.

MR imaging of intrahepatic cholangiocarcinoma with pathologic correlation

OBJECTIVE

The objective of this study was to determine the MR imaging features of intrahepatic cholangiocarcinoma.

MATERIALS AND METHODS

MR images of 50 patients with pathologically proven intrahepatic cholangiocarcinoma were reviewed retrospectively. T1- and T2-weighted spin-echo images were obtained in all patients. Contrast-enhanced T1-weighted imaging was performed in 25 patients. Signal intensity and enhancement pattern of the tumors were correlated with pathology findings. The frequency of central hypointense regions on T2-weighted images and the intrahepatic bile duct dilatation of several other hepatic tumor types were investigated. Results were compared with imaging results of cholangiocarcinoma.

RESULTS

On T2-weighted images, central hypo- and hyperintense regions were detected in tumors in 27 and 17 patients, respectively. Contrast-enhanced T1-weighted imaging revealed central hypointense areas exhibiting homogeneous, heterogeneous, and no enhancement in six, three, and five, respectively, of 14 patients. Regions of fibrosis displayed enhancement, whereas those of coagulative necrosis showed no enhancement. The signal intensity difference on T2-weighted images between the center and the edge of the tumor correlated well with the fibrotic ratio difference between those two areas corresponding to the MR image (Spearman's rank correlation test, r = 0.72, 95% confidence interval = 0.48-0.86). T2-weighted images revealed central hypointense regions in 16 of 34 instances of hepatic colorectal metastases. However, hypointensity was observed in only 26 of 234 other hepatic tumors. Intrahepatic bile duct dilatation was evident in 27 of 50 cases of cholangiocarcinoma but occurred in only a single case of 34 instances of hepatic colorectal metastases.

CONCLUSION

The combination of the signal intensity on T2-weighted images and the enhancement pattern on contrast-enhanced T1-weighted images showed good correlation with the pathologic findings of cholangiocarcinoma. The occurrence of a central hypointense area on T2-weighted images is not pathognomonic; however, this finding, which reflects severe fibrosis, appears to be a characteristic marker of intrahepatic cholangiocarcinoma. The presence of intrahepatic bile duct dilatation may indicate cholangiocarcinoma, although it is difficult to differentiate cholangiocarcinoma from hepatic colorectal metastasis.

Evaluation of the accuracy of gadobenate dimeglumine-enhanced MR imaging in the detection and characterization of focal liver lesions

OBJECTIVE

We evaluated the extent to which hepatic lesion characterization and detection is improved by using gadobenate dimeglumine for enhancement of MR images.

MATERIALS AND METHODS

Eighty-six patients were imaged before gadobenate dimeglumine administration, immediately after the 2 mL/sec bolus administration of a 0.05 mmol/kg dose (dynamic imaging), and at 60-120 min after the IV infusion at 10 mL/min of a further 0.05 nmol/kg dose (delayed imaging). The accuracy for lesion characterization was assessed for a total of 107 lesions. Sensitivity for lesion detection was assessed for a total of 149 lesions detected on either intra-operative sonography, iodized oil CT, CT during arterial portography, or follow-up contrast-enhanced CT as the gold standard.

RESULTS

The accuracy in differentiating benign from malignant liver lesions increased from 75% and 82% (the findings of two observers) on unenhanced images alone, to 89% and 80% on dynamic images alone (p<0.001, p = 0.8), and to 90.7% when combining the unenhanced and dynamic image sets (p<0.001, p = 0.023). Delayed images did not further improve accuracy (90% and 91%; p = 0.002, p< 0.05). A similar trend was apparent in terms of accuracy for specific diagnosis: values ranged from 49% and 62% on unenhanced images alone, to 76% and 70% on combined unenhanced and dynamic images (p<0.001, p = 0.06), and to 75% and 70% on inclusion of delayed images (p<0.001, p = 0.12). The sensitivity for lesion detection increased from 77% and 81% on unenhanced images alone, to 87% and 85% on combined unenhanced and dynamic images (p = 0.001, p = 0.267), and to 92% and 89% when all images were considered (p<0.001, p = 0.01).

CONCLUSION

Contrast-enhanced dynamic MR imaging with gadobenate dimeglumine significantly increases sensitivity and accuracy over unenhanced imaging for the characterization of focal hepatic lesions, and delayed MR imaging contributes to the improved detection of lesions.

Magnetic resonance imaging and diseases of the liver and biliary tract. Part 2. Magnetic resonance cholangiography and angiography and conclusions

Magnetic resonance cholangiography (MRC) relies on the strong T2 signal from stationary liquids, in this case bile, to generate images. No contrast agents are required, and the failure rate and risk of serious complications is lower than with endoscopic retrograde cholangiopancreatography (ERCP). Data from MRC can be summated to produce an image much like the cholangiogram obtained by using ERCP. In addition, MRC and conventional MRI can provide information about the biliary and other anatomy above and below a biliary obstruction. This provides information for therapeutic intervention that is probably most useful for hilar and intrahepatic biliary obstruction. Magnetic resonance cholangiography appears to be similar to ERCP with respect to sensitivity and specificity in detecting lesions causing biliary obstruction, and in the diagnosis of choledocholithiasis. It is also suited to the assessment of biliary anatomy (including the assessment of surgical bile-duct injuries) and intrahepatic biliary pathology. However, ERCP can be therapeutic as well as diagnostic, and MRC should be limited to situations where intervention is unlikely, where intrahepatic or hilar pathology is suspected, to delineate the biliary anatomy prior to other interventions, or after failed or inadequate ERCP. Magnetic resonance angiography (MRA) relies on the properties of flowing liquids to generate images. It is particularly suited to assessment of the hepatic vasculature and appears as good as conventional angiography. It has been shown to be useful in delineating vascular anatomy prior to liver transplantation or insertion of a transjugular intrahepatic portasystemic shunt. Magnetic resonance angiography may also be useful in predicting subsequent variceal haemorrhage in patients with oesophageal varices.

Biliary obstruction: findings at MR cholangiography and cross-sectional MR imaging

Twenty-two patients with malignant biliary obstruction and 21 patients with suspected obstruction of biliary-enteric anastomoses were evaluated over a 12-month period with magnetic resonance (MR) cholangiography and cross-sectional MR imaging. In patients with malignant obstruction, MR cholangiography helped accurately determine the status of the biliary ductal system by identifying the exact location and extent of the obstruction and the severity of duct dilatation. In so doing, MR cholangiography helped determine whether percutaneous transhepatic cholangiography with antegrade stent placement or retrograde cholangiography with stent placement constituted the more suitable treatment. Cross-sectional MR imaging was necessary to identify the organ of tumor origin, define the tumor margins, and determine the stage of disease. This information helped evaluate the appropriateness of curative surgical therapy versus palliative drainage procedures. In patients with biliary-enteric anastomoses, MR cholangiography clearly depicted the site of the anastomosis and demonstrated the status of the intrahepatic ducts, thereby helping determine which patients would benefit from undergoing antegrade duct cannulation with a drainage procedure or perhaps balloon dilation. In some of these patients, MR cholangiography was sufficient to help plan therapeutic intervention. MR cholangiography also demonstrates the presence and size of biliary stones and associated findings such as intraductal tumor growth. In addition, MR cholangiography may obviate retrograde cholangiography, which can be technically difficult to perform.

Peripheral cholangiocarcinoma (cholangiocellular carcinoma): clinical features, diagnosis and treatment

Peripheral cholangiocarcinoma is a relatively rare cancer. However, it is known to have an unfavourable prognosis compared with that of hepatocellular carcinoma. Little is known about its aetiology, clinical or pathological features. Recently, with the development of imaging modalities, early staged cholangiocarcinoma has been diagnosed with relative ease. Surgery is the optimal therapy. Total hepatectomy does not provide survival benefit. Conventional surgery remains the only effective treatment, even for patients with advanced-stage tumours. Factors influencing survival after hepatectomy were tumour-free margin, lymphnodes metastasis and histopathology of tumour. Palliative intrahepatic tubing or percutaneous transhepatic biliary drainage and brachytherapy can alleviate jaundice and cholangitis, thereby prolonging survival in some cases.

Intrahepatic peripheral cholangiocarcinoma: comparison of dynamic CT and dynamic MRI

PURPOSE

The purpose of this work was to compare dynamic MRI (D-MRI) with dynamic CT (D-CT) for the diagnosis of peripheral cholangiocarcinoma (PCC) of the liver.

METHOD

Twenty patients with PCC underwent both D-CT and D-MRI during the early, middle, and delayed phase after contrast medium administration. The findings from D-MRI were compared with those from D-CT.

RESULTS

D-CT and D-MRI exhibited a similar tumoral enhancement pattern, and this enhancement was more conspicuous on D-MRI. A wedge-like enhancement area peripheral to the tumor was observed in 9 (45%) patients on D-CT and 11 (55%) patients on D-MRI. Ductal dilatation was found in 13 (65%) patients on both techniques. Vascular involvement and extrahepatic invasion were seen in nine (45%) and two (10%) patients, respectively. The relationship of the tumor to the vessels and surrounding organs was more easily evaluated on D-CT.

CONCLUSION

Both D-CT and D-MRI can provide important information for the diagnosis of PCC. D-CT is better than D-MRI for demonstrating vascular involvement and extrahepatic invasion. D-MRI gives more conspicuous enhancement.

Cholangiocarcinoma: spectrum of appearances on MR images using current techniques

This study describes the spectrum of appearances of cholangiocarcinoma on magnetic resonance (MR) sequences, including gadolinium-enhanced, fat-suppressed spoiled gradient echo images and MR cholangiography. Fifteen patients were included in the study. Histologic diagnosis was established in 11 patients by surgical resection (6 patients), percutaneous biopsy (4 patients), and open liver biopsy (1 patient). The final diagnosis was determined by correlation of the MR findings with cholangiographic studies and laboratory studies in 4 patients. MR studies were performed at 1.5 T, and the following sequences were obtained: T1-weighted spoiled gradient echo (SGE), T1-weighted fat-suppressed spin echo or SGE, T2-weighted fat-suppressed conventional or turbo spin echo, MR cholangiography, and gadolinium-enhanced T1-weighted fat-suppressed SGE images. The following determinations were made: tumor location, tumor extent, ductal dilatation, ductal wall thickness, signal intensity, enhancement pattern, and associated findings. Mass-like neoplasms were peripheral (6 patients), hilar (1 patient), and extrahepatic (2 patients). Circumferential tumors were hilar (2 patients) and extrahepatic (4 patients). All peripheral tumors were multifocal. Mass-like tumors were well-defined, rounded, and ranged from 1 to 14 cm in diameter. Circumferential tumors had less well-defined margins and measured from 3 to 15 mm in thickness. All mass-like tumors were moderately hypointense on T1-weighted images and mildly to moderately hyperintense on T2-weighted images. The circumferential tumors were iso- to moderately hypointense on T1-weighted images and iso- to mildly hyperintense on T2-weighted images. Mass-like tumors were generally well shown on non-contrast and immediate gadolinium-enhanced images, whereas circumferential tumors were poorly seen on non-contrast images and best shown on gadolinium-enhanced T1-weighted fat-suppressed images. The degree of enhancement ranged from minimal to intense on immediate gadolinium-enhanced images, with all tumors becoming more homogeneous in signal intensity on images obtained between 1 and 5 min following contrast administration. Tumor-containing lymph nodes greater than or equal to 1 cm in diameter were demonstrated in 11 out of 15 patients (73.3%). These were best shown on T2-weighted fat-suppressed images and gadolinium-enhanced fat-suppressed SGE images. MR cholangiography demonstrated the level of obstruction and degree of dilatation of the proximal biliary system in 5 out of 6 patients who underwent MR cholangiography. The spectrum of appearances of cholangiocarcinoma is demonstrable on MR images. Mass-like tumors are well shown on both pre- and post-gadolinium sequences. Circumferential tumors may cause minimally increased duct wall thickness and are most clearly shown on gadolinium-enhanced fat-suppressed SGE images obtained 1 to 5 min following gadolinium administration.

Differential diagnosis of hepatic tumors with delayed enhancement at gadolinium-enhanced MRI: a pictorial essay

Hepatic lesions with delayed enhancement are sometimes encountered on gadolinium-enhanced MRI of the liver. This study illustrates the varied appearances of several pathologic entities with delayed enhancement, including hepatic hemangioma, hepatic metastases, intrahepatic cholangiocarcinoma, focal nodular hyperplasia, hepatic abscess, hepatocellular carcinoma, and hepatocellular carcinoma after transcatheter arterial chemoembolization, and presents the utility of arterial-phase dynamic MRI in the differential diagnosis of these lesions. Possible causes of these delayed enhancements are also discussed.

MRI of the liver

MRI of the liver is a powerful imaging modality for detection and characterization of liver pathology. MRI technology continues to evolve with developments in scanner hardware performance and refinements in imaging sequences, particularly in respect to fast imaging techniques, improving the quality of images that can be routinely achieved. Fast imaging techniques allow dynamic contrast-enhanced scanning to assist in lesion detection and characterization. An array of tissue-specific contrast agents are also becoming available; the clinical utility of some of these agents is yet to be fully established. An overview of scanning technique, contrast media, and the role of MRI in liver lesion detection and characterization is presented, with a review of the typical imaging characteristics of common focal and diffuse hepatic diseases. Where possible, emphasis has been placed on features that allow distinction between the various pathologic entities described.

MRI of clonorchiasis and cholangiocarcinoma

Intrahepatic cholangiocarcinomas are usually categorized as peripheral cholangiocarcinoma or hilar cholangiocarcinoma on the basis of the site of origin. Clonorchiasis is a trematodiasis caused by chronic infestation of liver flukes, which are largely confined to the Orient, from Japan to Vietnam. The close relationship between clonorchiasis and cholangiocarcinoma has long been emphasized. This paper discusses the efficacy and possible roles of MRI for imaging clonorchiasis and cholangiocarcinoma of the liver. Although sonography, CT, and direct cholangiography have been used traditionally to diagnose these diseases, the role of MRI has been increasing rapidly with dramatic progress of the MRI techniques. We review MRI findings of clonorchiasis and cholangiocarcinoma and discuss the potential usefulness of MRI.

Magnetic resonance imaging of focal and diffuse hepatic disease

MRI is a powerful tool in the detection and characterization of both focal and diffuse liver pathology. Because of superior soft tissue characterization, direct multi-planar capabilities and lack of ionizing radiation, current state of the art MRI is useful when contrast CT is relatively contraindicated or not definitive. This article reviews the MRI findings of the most common focal and diffuse liver diseases encountered in clinical practice. Reviews of current MR techniques and MR contrast agents used in liver imaging have been recently published. For this article, discussion of specific techniques and use of contrast is addressed for each pathological entity discussed.

Focal hepatic lymphoma: magnetic resonance demonstration using current techniques including gadolinium enhancement

This study demonstrates the appearance of focal hepatic lymphoma using current magnetic resonance techniques including gadolinium enhancement. Fifteen patients with hepatic lymphoma were imaged at 1.5T. T1-weighted, T2-weighted, immediate, and 5-10-min delayed T1-weighted spoiled gradient echo images were acquired in all patients. Determination was made of lesion size, number, morphology, and signal intensity of lesions on all sequences. Seven patients had solitary lesions and 8 patients had multiple lesions. Focal lesions of hepatic lymphoma ranged in size from 5 mm to 15 cm. They were well defined masses with mild to moderate low signal intensity relative to liver on T1-weighted images. Lymphoma lesions in 6 patients were moderately high in signal intensity on T2-weighted images compared with liver (Type I lesions), and enhancement of lesions was intense on early post-gadolinium images in 5 of these patients. Lymphoma lesions in 6 patients were mildly hypointense to mildly hyperintense on T2-weighted images compared to liver (Type II lesions), and lesions in 5 of these patients enhanced minimally on the early post-gadolinium spoiled gradient echo images. The remaining 3 patients had received chemotherapy before the magnetic resonance examination, and the imaging findings varied reflecting presumed differences in treatment responses. Transient ill defined perilesional enhancement on immediate post-gadolinium spoiled gradient echo images was observed in 9 patients including patients with either type of lesion. Focal lesions of hepatic lymphoma are usually low in signal intensity on T1-weighted images but have variable signal intensity on T2-weighted images. In general, lesions that are mildly hypointense to minimally hyperintense in signal intensity on T2-weighted images enhance minimally, and lesions moderately high in signal intensity of T2-weighted images enhance intensely. Transient increased perilesional enhancement is common.

Intrahepatic cholangiocarcinoma: MRI and pathologic correlation in 14 patients

PURPOSE

Our goal was to determine the MR features of intrahepatic cholangiocarcinoma and to correlate them with pathologic findings in a surgical series.

METHOD

MRI in 14 patients with intrahepatic cholangiocarcinoma who had undergone resection was reviewed. All patients had T1- and T2-weighted SE sequences. Contrast-material-enhanced MRI was performed in 12 cases. Comparison between findings at MRI and pathologic examination was made.

RESULTS

MRI depicted all the lesions but one satellite nodule of 2 cm diameter. All lesions were hypointense relative to the liver on T1-weighted images. On T2-weighted images, the tumors were predominantly isointense or slightly hyperintense relative to liver parenchyma in nine cases (64%) and were strongly hyperintense in five cases (36%). Central hypointense areas or bands were seen in eight cases. No capsule was detected. On contrast-enhanced MR studies, all lesions had progressive and concentric filling with contrast material. Associated findings such as vascular encasement, focal liver atrophy, or dilatation of intrahepatic bile ducts were observed in 10 cases (71%). Comparison with pathologic examination revealed that lesion signal intensity on T2-weighted MR images was due mostly to the amount of fibrosis, necrosis, and mucous secretion within the lesion. The nine isointense or slightly hyperintense lesions contained abundant fibrosis and had a low content of mucous secretion or necrosis, whereas the five hyperintense lesions contained low or moderate fibrosis and prominent mucous secretion and/or necrosis.

CONCLUSION

Our study suggests that the MR features of intrahepatic cholangiocarcinoma are well correlated with pathologic findings, but are nonspecific. Associated findings may strengthen the diagnosis of intrahepatic cholangiocarcinoma at MRI.

Renal cell cancer: incidence of hemorrhage on MR images in patients with chronic renal insufficiency

This study describes the occurrence of hemorrhage in renal cancer in patients with chronic renal insufficiency as shown on MR images. Thirteen consecutive patients with chronic renal insufficiency who had histologically proven renal cancer and underwent MRI at 1.5 T were entered in the study. MR examinations included spoiled gradient echo (SGE) and T1-weighted fat-suppressed imaging pre- and postgadolinium administration. All renal cancers were well shown on MR images and were most clearly depicted on postgadolinium T1-weighted fat-suppressed images. Tumors in 12 of 13 patients had regions of high signal intensity on precontrast T1-weighted images. Histology demonstrated intratumoral hemorrhage in all 12 of these patients. Four hemorrhagic tumors were largely cystic on imaging studies. One of these cancers altered in appearance from largely cystic with extensive hemorrhage to largely solid with substantial enhancement after a 2.5-year interval. Renal cancers demonstrated minimal enhancement (11 patients) on early postgadolinium images and were minimally enhanced on delayed images in 10 of 13 tumors. Two renal cancers demonstrated intense enhancement. Renal cancers are well shown on MR images in patients with chronic renal insufficiency. Because of the common occurrence of hemorrhage into renal cancers in patients with renal insufficiency, caution should be exercised when evaluating hemorrhagic cystic lesions in these patients.

Lingual carcinoma. Correlation of MR imaging with histopathological findings

PURPOSE

To determine the utility of MR imaging in the evaluation of lingual carcinomas.

MATERIAL AND METHODS

Eleven patients with lingual carcinoma were evaluated with MR imaging including dynamic study within one week before surgery. Nine patients underwent preoperative chemotherapy or irradiation, and 2 patients had no preoperative treatment. Delineation of the tumor, the contrast between tumor and surrounding tissue, and extent of the tumor were evaluated in a blinded manner. After glossectomy, MR images were correlated with pathological findings. Statistical analysis was performed on the visual assessment ratings.

RESULTS

Blinded evaluation suggested that dynamic and T2-weighted images (T2WI) were significantly superior to postcontrast T1WI in demonstrating the lesion. There were no significant differences between dynamic MR images and T2WIs. However, histopathological correlation showed that in patients with preoperative treatment, dynamic MR imaging demonstrated more accurately the size and extent of the residual tumor than did T2WI and postcontrast T1WI, which tended to demonstrate an area of signal abnormality that was more extensive than the true size of the residual lesion. In patients without preoperative treatment, dynamic MR imaging, T2WI, and postcontrast T1WI gave an equivalent depiction of the extent of the carcinoma.

CONCLUSION

In patients with no preoperative treatment, dynamic MR imaging does not appear to offer any advantage over T2WI. However, in patients with preoperative treatment, dynamic MR imaging provides a more accurate assessment of the residual tumor than do T2WI and postcontrast T1WI.

Fast MR imaging techniques: impact in the abdomen

The increased efficiency of MRI data acquisition has had a substantial impact on clinical MRI of the abdomen. Five particular applications that have thus been affected include breath-hold imaging of liver lesions (including detection, characterization, and biopsy), MR cholangiopan- creatography, practical chemical shift imaging (including liver and adrenal glands), dynamic imaging after contrast media injection, and MR angiography.