Intrabiliary MR imaging: Assessment of biliary obstruction with use of an intraluminal MR receiver coil

PURPOSE: The primary aim of this study was to determine whether intrabiliary magnetic resonance (MR) imaging is feasible in a clinical setting and to optimize MR imaging parameters for the technique. In addition, it was attempted to determine the accuracy of intrabiliary MR imaging in the setting of biliary obstruction of unknown cause. MATERIALS AND METHODS: Intrabiliary MR was performed prospectively in 15 patients with biliary obstruction of unknown cause. A 0.030-inch MR intravascular receiver coil was placed in an existing biliary tube. Intrabiliary MR was performed on a 1.5-T system. T1-weighted, T2-weighted, and single-shot fast spin-echo images were acquired. T1-weighted images were also acquired after the administration of a gadolinium contrast agent. Signal intensity analysis was conducted in the region of the common bile duct. Accuracy of intrabiliary MR, computed tomography (CT), MR, and cholangiography were determined by correlation with surgical pathologic findings. RESULTS: Intrabiliary MR was successfully performed in 14 of 15 patients. MR examinations were performed in less than 1 hour. The signal-to-noise ratio in the region of the common bile duct with the intrabiliary MR technique was increased by a factor of 9 compared with standard surface-coil MR imaging (P < .00001). The mean n-plane resolution achieved was 740 ± 20 μm × 1,150 ± 20 μm obtained with use of a field of view of 18 cm x 18 cm (range, 15-24 cm) and a matrix of 256 x 160. Of the pulse sequences tested, the gadolinium-enhanced T1-weighted image was the best for identifying tumor and delineating tumor margins. Intrabiliary MR had a higher sensitivity than CT (100% vs 50%), a higher specificity than cholangiography (80% vs 20%), and a better correlation (P = .015) with surgical pathologic findings than CT, MR imaging, or cholangiography. CONCLUSIONS: Intrabiliary MR was well tolerated in a clinical setting and provided high spatial resolution and excellent contrast between the biliary lumen and adjacent structures. Intrabiliary MR demonstrated an advantage in detecting the presence or absence of biliary malignancies compared with currently available standard imaging techniques. The technique may be useful to evaluate biliary obstruction of unknown cause.