Dynamic MRIによる移植腎機能の検討--予報--

Abstract

腎移植患者14例でGd-DTPA (dimeglumine gadopentetate)注射後small tip angle gradient echo法を行い, フリップ角は20度とした.Gd-DTPA注射前, 腎機能良好例では皮質は髄質に比し信号強度が高く, 注射30秒後で皮質の信号強度は低下し, 1分後に回復し, 皮髄境界付近に低信号帯を認めた.髄質の信号強度は3分後に低下した.5分後の実質の信号強度は注射前と大体同じであった.機能不良腎の画像は不明瞭であった.時間-信号強度曲線上, 機能良好腎では皮質及び髄質共に約2分後に急速に低下した後, 上昇し, 5分後は殆ど平坦であった.一方, 機能不良腎では検査の全経過を通じて殆ど平坦であった.時間-信号強度曲線におけるΔI1及びΔI2は移植腎機能の有効なパラメータであった

The value of dynamic magnetic resonance imaging (MRI) in the examination of the function of transplanted kidneys was examined. Dynamic MRI was performed on 14 renal transplant patients. After the injection of Gd-DTPA (dimeglumine gadopentetate), we used small tip angle gradient echo (STAGE) technique with a flip angle of 20 degrees. The cortex was higher in signal intensity of well functioning grafts than the medulla before the injection in Gd-DTPA. Signal intensity of the cortex decreased after 30 seconds. After 1 minute the signal intensity of the cortex recovered and low intensity band meaning passage of Gd-DTPA at corticomedullary differentiation was displayed. Signal intensity of the medulla decreased after 3 minutes. Signal intensity of the parenchyma of transplanted kidney after 5 minutes was much the same as that before injection. Image of poor functioning grafts displayed unclear figures. Time-intensity values of both cortex and medulla in well functioning grafts decreased rapidly after about 2 minutes, and rose thereafter. Time-intensity curves of both cortex and medulla were almost flat on and after 5 minutes. Time-intensity curves of both cortex and medulla in poor functioning grafts were almost flat through out the examination. We concluded that effective parameters of the graft function for the time-intensity curve were delta I1 and delta I2. Dynamic MRI was suggested to be useful in the evaluation of kidney graft function.