Differentiation of Delayed Kidney Graft Function with Gadolinium-DTPA-Enhanced Magnetic Resonance Imaging and Doppler Ultrasound

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Abstract
The authors differentiate acute tubular necrosis from transplant rejection in patients with delayed kidney graft function using gadolinium (Gd)-DTPA enhanced magnetic resonance (MR) imaging. Twenty-four patients after renal transplantation (10 with normal graft function, 14 with delayed graft function) underwent conventional and Doppler sonography and MR imaging examination after bolus application of Gd-DTPA. Within a time period of 512 seconds, 39 single-slice MR images were obtained. Measurements of signal intensity in three regions of interests (cortex, medulla, renal pelvis) resulted in a graphic description of the dynamics of the contrast enhancement. The time between the start of the scan and the peaks of the curves was measured. In patients with normal graft function the curves reached the peaks between 39 and 55 seconds (cortex), 44 and 61 seconds (medulla), and between 161 and 318 seconds (renal pelvis). Six patients with acute tubular necrosis showed normal values for the curves 1 and 2 but markedly prolonged time for curve 3 (between 420 and 512 seconds). In all patients with histologically proven transplant rejection, the peaks of all curves were not reached before the ends of the scans. The authors' preliminary results suggest that MR imaging seems to be a sensitive, noninvasive diagnostic tool to differentiate acute tubular necrosis from transplant rejection in the critical early postoperative period.