FUNCTIONAL MAGNETIC-RESONANCE-IMAGING OF HUMAN RENAL-ALLOGRAFTS DURING THE POSTTRANSPLANT PERIOD - PRELIMINARY-OBSERVATIONS

Graft dysfunction is a common occurrence during the first weeks follow ing renal transplantation. The current study was designed to evaluate the potential of renal magnetic resonance (MR) perfusion imaging to di fferentiate acute allograft rejection (AAR) from acute tubular necrosi s (ATN) during the post-transplant period, Twenty-three consecutive pa tients with clinically suspected ATN and/or AAR and eight consecutive control patients (asymptomatic, serum creatinine concentration < 1.5 m g/dL) underwent MR perfusion imaging of the renal allograft within 64 days after transplantation. Histopathology was obtained in all cases w ith clinical suspicion of ATN or AAR, Sixty sequential fast gradient-r ecalled-echo MK images were acquired in each patient after intravenous administration of gadolinium-DTPA (0.1 mmol/kg), Histopathology revea led 6 patients with pure AAR, 4 patients with a combination of AAR and ATN, 12 patients with ATN and 1 patient with normal findings, Kidney graft recipients with normal renal function showed a moderate increase in signal intensity (SI) of the renal cortex and medulla after admini stration of contrast agent followed by an immediate and short decrease in SI of the medulla (biphasic medullary enhancement pattern), The in crease in cortical SI of patients with AAR was significantly smaller ( 61 +/- 4% increase above baseline) than that measured in normal allogr afts (136 +/- 9% increase above baseline) (p < 0.05) and patients with ATN (129 +/- 3% increase above baseline) (p < 0.05), Patients with AT N had a slightly delayed and diminished cortical enhancement and an un iphasic and lesser medullary enhancement pattern compared to that obse rved in normal allografts (p < 0.05), A close correlation (r = 0.72) w as found between serum creatinine concentration levels and changes in SI, Thus, MR imaging results and histopathology were in agreement in 2 2 of 23 patients (96%), MR perfusion imaging of renal allografts can b e used to noninvasively differentiate ATN from AAR during the post-tra nsplant period, and may also be helpful in cases where covert AAR is s uperimposing ATN during a phase of anuria, Patients with ATN can be se parated from normals in the majority of cases as reflected by an uniph asic medullary enhancement pattern, (C) 1997 Elsevier Science Inc.