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 ao rtic aneurysms (AAA), an initial 'timing' single level CT is commonly perfo rmed with a small bolus of contrast. This can be exploited to obtain adjunc t functional information on renal perfusion. We have investigated the poten tial of this to measure renal perfusion, to produce colour renal perfusion maps and to predict surgical outcome in infrarenal aortic aneurysm assessme nt.;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 aor ta was scanned after the intravenous injection of 25 mi of contrast given a t 10 ml/s. Ten 1 s duration scans were performed from 8 to 30 s after injec tion. Optimal timing for CT angiography can then be determined. Time-densit y curves were then drawn for both kidneys and aorta using regions of intere st (ROIs) or pixel-by-pixel analysis. Renal cortical perfusion was measured using both ROI analysis and pseudocolour perfusion images. Following previ ous work, perfusion was calculated as the peak upslope of the tissue time d ensity curve divided by peak aortic enhancement. Results: Cortical mean per fusion 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: Additiona l functional data and imaging can be obtained from the initial timing scan of a CT study, without requiring a dedicated study. (C) 1999 Elsevier Scien ce Ireland Ltd. All rights' reserved.