Functional renal perfusion imaging with colour mapping:: is it a useful adjunct to spiral CT of in the assessment of abdominal aortic aneurysm (AAA)?

Aim: To ensure optimal timing with pre-operative spiral CT for abdominal aortic aneurysms (AAA), an initial 'timing' single level CT is commonly performed with a small bolus of contrast. This can be exploited to obtain adjunct functional information on renal perfusion. We have investigated the potential of this to measure renal perfusion, to produce colour renal perfusion maps and to predict surgical outcome in infrarenal aortic aneurysm assessment.;Methods: We studied 21 patients being assessed for repair of infrarenal AAA. Prior to the spiral CT, a single level through the renal hill and aorta was scanned after the intravenous injection of 25 mi of contrast given at 10 ml/s. Ten 1 s duration scans were performed from 8 to 30 s after injection. Optimal timing for CT angiography can then be determined. Time-density curves were then drawn for both kidneys and aorta using regions of interest (ROIs) or pixel-by-pixel analysis. Renal cortical perfusion was measured using both ROI analysis and pseudocolour perfusion images. Following previous work, perfusion was calculated as the peak upslope of the tissue time density curve divided by peak aortic enhancement. Results: Cortical mean perfusion averaged 2.48 ml/min per mi (range 0.8-3.7 ml/min per mi n = 34) and the values obtained agreed with literature expectations. Follow up in the 10 patients proceeding to AAA. repair suggest low mean perfusion values and predict a raised postoperative creatinine (P < 0.05) Conclusion: Additional functional data and imaging can be obtained from the initial timing scan of a CT study, without requiring a dedicated study. (C) 1999 Elsevier Science Ireland Ltd. All rights' reserved.