The correlation between MR and angiography in portal hypertension.

Forty-two MR examinations and hepatic panangiograms in 38 patients with portal hypertension were correlated with MR images to determine the ability of MR to detect portal vein hemodynamics. These studies were prospectively analyzed for degree of portal perfusion and direction of flow, portal vein thrombosis, and presence and type of shunt surgery. Thirty-three MR examinations were determined to have grade I (good) or II (fair) portal blood flow. Twenty-nine of these were grade I or II by angiography; the other four were grade IV. Of the eight cases documented as grade IV (hepatofugal portal blood flow) by angiography, none were considered grade IV by MR, suggesting that MR was unable to detect retrograde flow. The other case was not graded because of cavernous transformation of the portal vein. MR correlated well with angiography for the detection or absence of portal vein thrombus, agreeing with angiography in 41 of 42 cases. Two angiographically proven cases of portal vein thrombosis were correctly identified on MR. MR correctly identified the absence of portal vein clot in 39 of 40 angiographically negative cases. MR and angiography also agreed in 41 of 42 cases that a shunt was either present/absent or patent/occluded. The single error was due to inadequate MR scanning in the region of interest. The results show that MR cannot be used to grade blood flow in the portal vein. However, MR accurately detects portal vein thrombosis and the patency of surgical shunts.