Deconvolution analysis of renal blood flow: evaluation of postrenal transplant complications.

UNLABELLED: Medical complications after renal transplantation cause problems in treatment decision making. To differentiate acute tubular necrosis from acute rejection when it occurs in the early posttransplant period is difficult. Renal scintigraphy offers a noninvasive means for renal blood flow (RBF) and renal function assessment.
METHODS: This retrospective study of RBF and renal function evaluation after kidney transplantation is an attempt to calculate the "renal vascular transit time" from the 99mTc-diethylenetriaminepentaaacetic acid renal vascular flow with a deconvolution technique. The results of 102 studies on 38 graft recipients were evaluated. Of these, 19 were diagnosed as acute rejection, 12 as acute tubular necrosis, 4 as chronic rejection, 1 as vesicoureteric reflux, 1 as recurrent immunoglobulin A nephropathy, 1 as iliac vein thrombosis, 1 as cyclosporine nephrotoxicity and 63 as normal. All diagnoses were established by clinical and/or pathologic criteria.
RESULTS: With renal vascular transit times more than 12.8 secm the sensitivity and specificity for the detection of acute rejection was 95% and 94%, respectively. The sensitivity and specificity for the differential diagnosis of acute rejection against acute tubular necrosis was 95% and 92%, respectively.
CONCLUSION: The use of renal vascular transit time in addition to 131I-labeled hippuran renogram provides a promising diagnostic parameter to differentiate between acute rejection and acute tubular necrosis.