Assessment of renal allograft pathology by scintigraphic and ultrasound index-markers

The efficacies of two scintigraphic and two sonographic techniques and resultant index values, as markers of renal allograft pathology, were assessed. Index values of 183 combined scintigraphic and sonographic examinations in 47 graft recipients were compared to the pathological diagnosis of transplant biopsies and subsequent clinical outcome. All recipients were studied with baseline imaging techniques postoperatively, again when indicated by predefined clinical criteria, and prior to graft biopsy. The scintigraphic technique involved the calculation of indices of thrombotic activity and cortical graft perfusion. Ultrasound involved determination of the Doppler resistance index of Pourcelot and estimations of graft volume from real time images. A decreased cortical perfusion index was, overall, the most sensitive index of acute or chronic graft pathology, but it lacked specificity. Increased thrombotic and resistance indices were 96% and 86% sensitive for acute vascular rejection and were 82% and 76% specific. Jointly increased thrombotic and resistance indices improved the specificity for acute vascular rejection to 98%. An increase in graft volume of more than 50% over stable values was 100% sensitive and 92% specific for acute interstitial rejection, and 95% specific when paired with a normal thrombotic index. A marked increase in the thrombotic index was 100% sensitive for cyclosporine-induced thrombotic microangiopathy, but only 49% specific. The specificity of a markedly increased thrombotic index for thrombotic microangiopathy improved to 93% when the Doppler resistance index remained normal or was only marginally elevated. None of the scintigraphic or ultrasound indices were helpful for the diagnosis of acute tubular necrosis, chronic rejection, recurrent glomerulopathy, or graft infection.