Are There MRI Features of Early Bile Duct Neoplasm?

Are There MRI Features of Early Bile Duct Neoplasm?

A recent study was conducted to determine if there are MRI findings that can aid in the detection of early bile duct neoplasms.

The results, published in a recent issue of The Journal of Magnetic Resonance Imaging, indicates that early bile duct neoplasms can be detected when using magnetic resonance cholangiopancreatography (MRCP) combined with dynamic contrast-enhanced MRI.

The Study
17 patients with surgically proven early bile duct cancer.

Methodology
Early bile duct neoplasm was diagnosed when the lesion was confined to the bile duct wall and depth of invasion was confined within the fibromuscular layer.

MRI examinations were performed on 1.5-Tesla systems. Sequences included T2 half-Fourier acquired single-shot turbo spin-echo (HASTE) and fat-suppressed 3-dimensional gradient recalled echo sequence prior to and following dynamic administration of IV gadolinium.

Magnetic resonance cholangiopancreatography (MRCP) examinations were performed with thin-slab multi-section HASTE and thick-slab T2-weighted turbo spin-echo sequences.

Images were reviewed by 2 radiologists. T2-weighted MRCP images were first evaluated.

Signal intensities and degrees of enhancement were classified  as: hypointense, iso-intense, or hyperintense relative to the hepatic parenchyma.

The outer margin of the narrowed bile duct wall was classified as indistinct if there was marginal blurring, speculation, or irregularity. The signal-to-noise ratio of the tumor relative to the normal bile duct wall was also calculated.

Results of Study
All patients had intraductal masses found at surgery. These masses were well demonstrated on MRCP, and had sharply defined outer margins.

On unenhanced images, all tumors were hyperintense compared with the hepatic parenchyma on T2-weighted images, and all but 2 were low-signal intensity on T1-weighted images.

The outer margin of the bile duct segment containing the tumor was sharply defined on T2-weighted images in all but 1 patient.

The inner surface of the tumor had a papillary appearance in 13 patients, irregular surface in 3, and smooth margin in 1.

During the arterial phase, most biliary tumors demonstrated heterogeneous enhancement consisting of an amorphous pattern, central dots, or a central vascular structure.

The outer margin of the bile duct wall with the tumor was sharply defined in all but one patient on the delayed-phase image.

The signal-to-noise ratio of the bile duct wall was greater than that of the neoplasm, but the difference in signal-to-noise ratio of the tumor relative to the normal bile duct wall was statistically significant in only delayed-phase images.

Reviewer’s Comments
The results of this study are useful in demonstrating that magnetic resonance cholangiopancreatography (MRCP) combined with dynamic contrast-enhanced MRI can be valuable in detecting early bile duct neoplasms. These are typically intraductal and papillary.

In addition, the combined imaging findings can aid in determining lesion resectability.

One of the limitations reported in this study was the small sample size, although the detection of early bile duct neoplasm is difficult, which consequently supports the small size of the study population.

Author: John C. Sabatino, MD, MSD

Reference:
Lee DH, Lee JM, et al. MR Imaging Findings of Early Bile Duct Cancer. J Magn Reson Imaging; 2008;28 (December): 1466-147