ASSESSMENT OF RENAL-ARTERY STENOSIS WITH CT ANGIOGRAPHY - USEFULNESS OF MULTIPLANAR REFORMATION, QUANTITATIVE STENOSIS MEASUREMENTS, AND DENSITOMETRIC ANALYSIS OF RENAL PARENCHYMAL ENHANCEMENT AS ADJUNCTS TO MIP FILM READING

Purpose: Our goal was to evaluate CT angiography (CTA) in diagnosing r enal artery stenosis (RAS). Method: Thirty-seven patients underwent di gital subtraction angiography (DSA) and CTA. Visual interpretation and stenosis measurements were made from maximum intensity projection (MI P) and multiplanar reformation (MPR) laser film prints of 78 renal art eries. Results: Visual reading of MIP films showed good diagnostic per formance by receiver operating characteristic curve analysis, with 100 % sensitivity in the assessment of greater than or equal to 50% RAS bu t only 42-54% specificity (overall accuracy 60-75%). The false-positiv e rate decreased when MIP and MPR films were read together, but the ex cess of false negatives among the calcified lesions disabled this diag nostic algorithm. Combining visual interpretation of MIP films with qu antitative measurements yielded the best diagnostic performance: 92% s ensitivity, 80% specificity, and 84% overall accuracy. Renal cortical enhancement measurements (26 patients) had 81% overall accuracy. Concl usion: The overall accuracy of CTA with MIP film reading can be enhanc ed by quantitative measurement of stenosis or reviewing MPRs.