Lohr J, Mazurchuk R J, Acara M A, Nickerson P A, Fiel R J
Department of Medicine, State University of New York, Buffalo.
Magn Reson Imaging. 1991;9(1):93-100. doi: 10.1016/0730-725x(91)90102-r.
Proton magnetic resonance imaging was performed on rats before induction of diabetes with streptozotocin (STZ) and at 2 and 12 days postinduction. Images revealed an increase in maximal longitudinal and axial dimensions of the kidneys at 2 days and a further increase at 12 days. Similarly, an increase in the size of the remaining kidney was seen in a rat which underwent uninephrectomy as a positive control. Two major differences were observed between the kidney undergoing compensatory hypertrophy and those developing diabetic nephropathy: (i) Expansion of the renal vasculature was seen only in images of the diabetic rat; (ii) A loss in conspicuity of the normal corticomedullary junction was seen in the T2-weighted images of the diabetic rat but not in the uninephrectomized rat. Histologic examination revealed that the medulla increased to a size greater than the cortex during diabetic nephropathy whereas the medullary volume was less than that of the cortex during compensatory hypertrophy. In vitro T1 relaxation times in cortex, outer medulla and inner medulla of kidneys from control rats were measured and compared with the same respective regions in diabetic rats. When these values were correlated with tissue water content, a linear increase in relaxation rate versus percent water content from cortex to inner medulla was found in the control kidneys, but this correlation was absent in diabetic nephropathy. These studies demonstrate that MRI is an effective noninvasive tool for studying the course of renal hypertrophy and hydration changes in the development of renal disease in STZ-induced diabetes in the rat.
在大鼠用链脲佐菌素（STZ）诱导糖尿病之前以及诱导后2天和12天进行质子磁共振成像。图像显示，肾脏的最大纵向和轴向尺寸在诱导后2天增加，在12天时进一步增加。同样，在作为阳性对照进行了单侧肾切除术的大鼠中，观察到剩余肾脏的大小增加。在经历代偿性肥大的肾脏与发生糖尿病肾病的肾脏之间观察到两个主要差异：（i）仅在糖尿病大鼠的图像中可见肾血管系统扩张；（ii）在糖尿病大鼠的T2加权图像中可见正常皮质髓质交界处的清晰度丧失，而在单侧肾切除的大鼠中未见。组织学检查显示，在糖尿病肾病期间髓质增大至大于皮质的大小，而在代偿性肥大期间髓质体积小于皮质。测量了对照大鼠肾脏皮质、外髓和内髓的体外T1弛豫时间，并与糖尿病大鼠相同的相应区域进行比较。当这些值与组织含水量相关时，在对照肾脏中发现从皮质到内髓弛豫率与水含量百分比呈线性增加，但在糖尿病肾病中不存在这种相关性。这些研究表明，MRI是研究大鼠STZ诱导糖尿病中肾脏肥大过程以及肾脏疾病发展过程中水分变化的一种有效的非侵入性工具。
