[Magnetic resonance imaging, with surface coil, of a transplanted kidney]

MR appearance of the kidney transplant is evaluated on a series of 80 examinations performed on a supraconductive unit operating at 0.5 T. Normal function kidneys displayed a clearly delineated corticomedullary differentiation (CMD); the ratio between the thickness of cortex and medulla didn't exceed 0.6. The same appearance was observed in non complicated acute tubular necrosis. Complete loss of CMD was the major finding in acute rejection (74% of the cases), but it was not specific as it was also observed in chronic rejection and in acute glomerulonephritis. Cortex thickening was helpful for the detection of rejected transplants with visible CMD. The sensitivity of MR in the detection of acute rejection was 94%. Specificity of MR findings for acute rejection depended on the transplant age: it varied from 100% for examinations performed during the first 3 months after transplantation, to less than 50% for examinations of the second year.