EVALUATION OF MALIGNANT BILIARY OBSTRUCTION - EFFICACY OF FAST MULTIPLANAR SPOILED GRADIENT-RECALLED MR-IMAGING VS SPIN-ECHO MR-IMAGING, CT, AND CHOLANGIOGRAPHY

OBJECTIVE. Although CT and cholangiography have proven value in the de tection of biliary obstruction, determining the extent of biliary tumo rs and imaging small pancreatic or ampullar tumors remain problematic. We hypothesized that the superior contrast resolution of MR, coupled with contrast-enhanced breath-hold imaging, might increase the sensiti vity for tumor detection and improve the depiction of the point of obs truction in patients with malignant biliary disease. SUBJECTS AND METH ODS. Twenty-one MR studies were performed prospectively in patients wi th malignant biliary obstruction by obtaining breath-hold contrast-enh anced fast multiplanar spoiled gradient-recalled (FMPSPGR) images at 0 and 10 min, conventional spin-echo T1-weighted images, and fast spin- echo TP-weighted images. Findings on MR images were correlated with fi ndings on CT scans (15 cases) and/or cholangiograms (14 cases) by two observers. All MR images, CT scans, and cholangiograms were reviewed t o evaluate tumor detection, visualization of dilated bile ducts, and c onspicuity of the obstructing tumor. A four-point scale (1 = excellent tumor depiction and conspicuity, 4 = tumor not detected) was used for evaluation. Contrast-to-noise ratios for tumor and bile were calculat ed for the three MR pulse sequences. RESULTS. The contrast-enhanced FM PSPGR images and CT scans provided excellent depiction of the dilated biliary tree in 95% and 93% of examinations, respectively, with both t echniques superior to fast spin-echo and T1-weighted images (p < .005) . Tumor detection was best with the immediate FMPSPGR MR images (20/21 ), compared with fast spin-echo MR images (16/21) (p = .04), T1-weight ed MR images (16/21) (p = .04), CT scans (12/15) (p > .05), and cholan giograms (13/14) (p > .05). Of 13 examinations showing proximal biliar y obstruction, the mean score for tumor conspicuity was best with the immediate enhanced FMPSPGR MR images (1.38 +/- .65), compared with T1- weighted MR images (2.38 +/- 1.3) and fast spin-echo MR images (2.08 /- 1.0) (p < .05), but it was not different from the delayed FMPSPGR M R images (1.75 +/- 1.1) or CT scans (1.9 +/- 0.99) (p > .05). For five of six cholangiocarcinomas, the immediate and delayed enhanced FMPSPG R MR images showed excellent tumor conspicuity owing to their enhancem ent with gadopentetate dimeglumine. Data for contrast-to-noise ratios of tumor showed that the immediate FMPSPGR MR images (15.8 +/- 10.2) w ere superior to T1-weighted images (6.3 +/- 3.5, p < .01), but were no t different from fast spin-echo images (13.5 +/- 6.7) or delayed FMPSP GR images (11.5 +/- 8.9). For eight examinations in patients with dist al biliary obstruction, the mean score for tumor conspicuity was great er with the immediate FMPSPGR MR images (1.38 +/- 0.52), compared with fast spin-echo images (3.25 +/- 0.71, p < .005), T1-weighted images ( 2.63 +/- 1.06, p < .05), and delayed FMPSPGR MR images (2.60 +/- 1.5, p < .05), but was similar to that with CT scans (1.40 +/- 0.89, p > .0 5). Data for contrast-to-noise ratios of tumor showed an advantage for the immediate FMPSPGR MR images (12.0 +/- 7.7) over T1-weighted image s (4.0 +/- 2.6, p < .0l) and delayed FMPSPGR images (4.3 +/- 2.6, p < .025), but no difference from fast spin echo images (6.6 +/- 8.8, p = .05). CONCLUSION. Contrast-enhanced FMPSPGR MR imaging is sensitive fo r the detection of tumors causing biliary obstruction. For proximal ob struction, it may be particularly effective for detecting and defining tumor extent of hilar cholangiocarcinomas because of their enhancemen t with gadopentetate dimeglumine. For cases of distal obstruction, thi s technique showed improved tumor detection and conspicuity compared w ith T1- and fast spin-echo T2-weighted images, but showed no advantage over CT.