MR imaging findings of early bile duct cancer

Intraductal magnetic resonance imaging of cholangiocarcinoma - a practical possibility

Intraductal T2 mapping based on a catheter receiver is proposed as a method of visualizing the extent of intraductal and periductal cholangiocarcinoma (CCA). Compared to external receivers, internal receivers provide locally enhanced signal-to-noise ratios by virtue of their lower field-of-view for body noise, allowing smaller voxels and higher resolution. However, inherent radial sensitivity variation and segmentation for patient safety both distort image brightness. We discuss simulated T2 weighted images and T2 maps, and in vitro images obtained using a thin film catheter receiver of a freshly resected liver specimen containing a polypoid intraductal tumor from a patient with CCA. T2 mapping provides a simple method of compensating non-uniform signal reception patterns of catheter receivers, allowing the visualization of tumor extent without contrast enhancement and potentially quantitative tissue characterization. Potential advantages and disadvantages of in vivo intraductal imaging are considered.

ACR Appropriateness Criteria® Jaundice

Jaundice is the end result of myriad causes, which makes the role of imaging in this setting particularly challenging. In the United States, the most common causes of all types of jaundice fall into four categories including hepatitis, alcoholic liver disease, blockage of the common bile duct by a gallstone or tumor, and toxic reaction to a drug or medicinal herb. Clinically, differentiating between the various potential etiologies of jaundice requires a detailed history, targeted physical examination, and pertinent laboratory studies, the results of which allow the physician to categorize the type of jaundice into mechanical or nonmechanical causes. Imaging modalities used to evaluate the jaundiced patient (all etiologies) include abdominal ultrasound (US), CT, MR cholangiopancreatography, endoscopic retrograde cholangiopancreatography and endoscopic US. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

In Vitro Intraductal MRI and T2 Mapping of Cholangiocarcinoma Using Catheter Coils

AIM

Diagnostic imaging of early-stage cholangiocarcinoma is challenging. A previous in vitro study of fixed-tissue liver resection specimens investigated T2 mapping as a method of exploiting the locally increased signal-to-noise ratio (SNR) of duodenoscope coils for improved quantitative magnetic resonance imaging (MRI), despite their non-uniform sensitivity. This work applies similar methods to unfixed liver specimens using catheter-based receivers.

METHODS

Ex vivo intraductal MRI and T2 mapping were carried out at 3T on unfixed resection specimens obtained from cholangiocarcinoma patients immediately after surgery using a catheter coil based on a thin-film magneto-inductive waveguide, inserted directly into an intrahepatic duct.

RESULTS

Polypoid intraductal cholangiocarcinoma was imaged using fast spin-echo sequences. High-resolution T2 maps were extracted by fitting of data obtained at different echo times to mono-exponential models, and disease-induced changes were correlated with histopathology. An increase in T2 was found compared with fixed specimens and differences in T2 allowed the resolution of tumour tissue and malignant features such as polypoid morphology.

CONCLUSION

Despite their limited field of view, useful data can be obtained using catheter coils, and T2 mapping offers an effective method of exploiting their local SNR advantage without the need for image correction.

Improving the Detection of Cholangiocarcinoma: In vitro MRI-Based Study Using Local Coils and T2 Mapping

Aim

Cholangiocarcinoma is endemic in southeast Asia, generally developing from liver fluke infestation. However, diagnostic imaging of early-stage disease is challenging. The aim of this work is to investigate relaxometry (specifically, T2 mapping) as a method of exploiting the higher signal-to-noise ratio (SNR) of internal coils for improved reception of magnetic resonance signals, despite their non-uniform sensitivity.

Methods

Ex vivo T2 mapping was carried out at 3T on fixed resection specimens from Thai cholangiocarcinoma patients using an mGRASE sequence and an endoscope coil based on a thin-film magneto-inductive waveguide and designed ultimately for internal use.

Results

Disease-induced changes including granulomatous inflammation, intraepithelial neoplasia and intraductal tumours were correlated with histopathology, and relaxation data were compared with mono- and bi-exponential models of T2 relaxation. An approximately 10-fold local advantage in SNR compared to a 16-element torso coil was demonstrated using the endoscope coil, and improved tissue differentiation was obtained without contrast agents.

Conclusion

The performance advantage above follows directly from the inverse relation between the component of the standard deviation of T2 due to thermal noise and the SNR, and offers an effective method of exploiting the SNR advantage of internal coils. No correction is required, avoiding the need for tracking, relaxing constraints on coil and slice orientation and providing rapid visualization.

Cross-Sectional Imaging of Intrahepatic Cholangiocarcinoma: Development, Growth, Spread, and Prognosis

OBJECTIVE

Intrahepatic cholangiocarcinoma (ICC) is a malignant tumor that arises from the intrahepatic bile ducts. Although the pathologic and imaging features of ICC have been clearly identified, recent updates have addressed the pathologic classification and imaging features of ICC using new imaging techniques. First, a proposed new pathologic ICC subclassification includes perihilar large duct and peripheral small duct ICCs. Second, advanced MR-based imaging features of ICC, such as hepatobiliary phase imaging using hepatocytespecific contrast material and DWI, have recently been described. These imaging features are important when differentiating ICCs from hepatocellular carcinomas. Finally, some imaging features of ICC, such as prominent arterial enhancement or degree of delayed enhancement, exhibit potential as prognostic imaging biomarkers.

CONCLUSION

Comprehensive and updated knowledge of ICC is necessary for accurate diagnosis and could facilitate prediction of clinical outcomes for patients with ICC.

Imaging bile duct tumors: pathologic concepts, classification, and early tumor detection

Cholangiocarcinoma is the most common primary malignancy of the bile ducts which has several predisposing factors such as hepatolithiasis and primary sclerosing cholangitis, and can develop from precancerous conditions such as biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile duct. As surgical resection of early stage cholangiocarcinoma or precancerous lesions may provide better prognosis, early detection of those lesions is very important. Imaging studies play important roles in the diagnosis of bile duct tumors followed by appropriate management. Indeed, not only diagnosis of cholangiocarcinoma but also appropriate categorization of bile duct tumors based on their morphologic features and location on cross-sectional imaging studies, including computed tomography and magnetic resonance imaging, is important to predict their biologic behaviors, and choose relevant treatment strategies. We herein review the classification system of the bile duct tumors with their radiologic and pathologic findings as well as role of imaging in the early detection of bile duct tumors.

Magnetic resonance evaluations of biliary malignancy and condition at high-risk for biliary malignancy: Current status

Tumors of the biliary tree are relatively rare; but their incidence is rising worldwide. There are several known risk factors for bile duct cancers, and these are seem to be associated with chronic inflammation of the biliary epithelium. Herein, 2 risk factors have been discussed, primary sclerosing cholangitis and reflux of pancreatic juice into the bile duct, as seen in such as an abnormal union of the pancreatic-biliary junction because magnetic resonance imaging (MRI) is used widely and effectively in the diagnosis of these diseases. When biliary disease is suspected, MRI can often help differentiate between benignity and malignancy, stage tumors, select surgical candidates and guide surgical planning. MRI has many advantages over other modalities. Therefore, MRI is a reliable noninvasive imaging tool for diagnosis and pre-surgical evaluation of bile duct tumors. Nowadays remarkable technical advances in magnetic resonance technology have expanded the clinical applications of MRI in case of biliary diseases. In this article, it is also discussed how recent developments in MRI contributes to the diagnosis of the bile duct cancer and the evaluation of patients with risk factors affecting bile duct cancer.

The T1W hyperintense signal on the surface of distal segment of bile duct tumor thrombi and its significance

RATIONALE AND OBJECTIVES

To evaluate the magnetic resonance (MR) findings of bile duct tumor thrombi (BDTT) and intraductal growing-type cholangiocarcinoma (IDG-type CC), especially focusing on the distal segment of intrabiliary tumors.

MATERIALS AND METHODS

Twenty-nine cases of hepatocellular carcinoma with BDTT and 17 cases of IDG-type CC were available for retrospective review. The following MR findings were evaluated: presence of necrosis and T1-weighted (T1W) hyperintense signal on the surface of the distal segment of intrabiliary tumors, bile duct wall thickening adjacent to the tumor, dilation of bile duct of the tumor-bearing segment, location and maximum diameter of intraductal mass, and presence of a hepatic parenchymal mass.

RESULTS

There was significant difference in T1W hyperintense signal on the surface of the distal segment of intrabiliary tumors between BDTT and IDG-type CC (P < .05). The T1W hyperintense signal detected in BDTT was identified as bile layering (9/25) or hemobilia (16/25) pathologically. For the diagnosis of BDTT, the sensitivity and specificity of T1W hyperintense signal was 86.2% and 100%, respectively. There was significant difference in necrosis at the distal end of intrabiliary tumors and presence of hepatic parenchymal mass between BDTT and IDG-type CC (P < .05). However, no statistical significance was found in bile duct dilation, the absence of wall thickening, the location of intraductal mass, or the maximum diameter of intrabiliary mass between the two groups (P > .05).

CONCLUSIONS

The T1W hyperintense signal on the distal segment of intrabiliary mass was because of concentrated bile deposits or hemobilia. The sign of T1W hyper signal on the distal segment is valuable to differentiate BDTT and IDG-type CC.

Differentiation of intraductal growing-type cholangiocarcinomas from nodular-type cholangiocarcinomas at biliary MR imaging with MR cholangiography

PURPOSE

To describe the magnetic resonance (MR) findings of intraductal growing (IDG)-type cholangiocarcinoma (CC) and to identify the features that differentiate it from nodular-type CC.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the informed consent requirement. Thirty-nine patients with pathologically proved IDG-type (n = 19) or nodular-type (n = 20) CCs who had undergone preoperative gadolinium-enhanced MR imaging with MR cholangiography were included in this study. Analysis of MR findings included determination of the (a) shape, enhancement degree, and pattern of the tumor; (b) outer caliber of the tumor-bearing segment; and (c) presence of tumor multiplicity, upstream and downstream bile duct dilatation, bile duct wall thickening adjacent to the tumor, and adjacent organ invasion. The significance of these findings was determined with the χ² test.

RESULTS

Significant features in the differentiation of IDG-type CCs from nodular-type CCs included papillary or irregular polypoid shape, lack of constriction of the tumor-bearing segment, hypoenhancement of the tumor to the liver during the equilibrium phase, tumor multiplicity, upstream and downstream bile duct dilatation, and no bile duct wall thickening adjacent to the tumor (P < .05). When at least two of these six imaging features were used in combination, sensitivity and specificity in the diagnosis of IDG-type CCs were 95% and 70%, respectively.

CONCLUSION

By using characteristic MR features, one can differentiate IDG-type CC from nodular-type CC with a high degree of accuracy at biliary MR imaging with MR cholangiography.