HEMODYNAMIC SIGNIFICANCE OF RENAL-ARTERY STENOSIS - DIGITAL SUBTRACTION ANGIOGRAPHY VERSUS SYSTOLICALLY GATED 3-DIMENSIONAL PHASE-CONTRAST MR-ANGIOGRAPHY

PURPOSE: To compare digital subtraction angiography with three-dimensi onal phase-contrast magnetic resonance (MR) angiography in detection o f significant renal artery stenosis. MATERIALS AND METHODS: Sixteen pa tients underwent digital subtraction angiography and systolically gate d three-dimensional phase-contrast MR angiography within 1 week. Scori ng of stenosis on MR angiograms was based on presence and length of a flow void and quality of flow signal intensity in the distal part of t he artery. Intraarterial pressure measurement was the reference standa rd for hemodynamically significant renal artery stenosis. RESULTS: MR angiography depicted two of five patent accessory arteries. Comparison of digital subtraction angiography and MR angiography with intraarter ial pressure measurements was possible in 25 main renal arteries. In 1 3 arteries, a pressure gradient of more than 15 mm Hg was found. Digit al subtraction angiography depicted 10 of these stenoses (sensitivity, 77%; specificity, 92%). A flow void was present at MR angiography in eight stenoses (sensitivity, 62%; specificity, 83%). In 12 of the sten osed vessels, distal flow signal intensity was impaired at MR angiogra phy (sensitivity, 92%; specificity, 75%). There was no difference betw een the two modalities (P >.05) in grading hemodynamic significance of renal artery stenosis. CONCLUSION: Systolically gated MR angiography and digital subtraction angiography are equally effective in depicting hemodynamically significant stenoses in the main renal arteries. MR a ngiography, however, is not adequate in depiction of accessory renal a rteries.