磁共振T2弛豫时间和表观弥散系数对孤肾猪肾缺血再灌注损伤后病理过程的监测

T2 relaxation time and apparent diffusion coefficient for noninvasive evaluation of renal pathology after renal ischemia -reperfusion injury in solitary -kidney porcine

目的探讨磁共振（MRDT2弛豫时间和表观弥散系数（ADC）在无创性监测肾缺血再灌注损伤后病理过程中的作用。方法12头猪按照是否接受肾动脉主干阻断（MRAC）随机分成两组，即对照组（Control组）和MRAC组，每组6头。麻醉后切除右肾，制造孤肾模型。再取左侧与腰骶肌平行切口，Control组仅分离而不夹闭左侧肾动脉主干，MRAC组夹闭左侧肾动脉主干，60min后去除血管夹。于术前及术后1、7、28、90d进行MRI扫描，检测T2弛豫时间和ADC值；术后第1、90天每组处死3头猪，取左肾行病理观察。结果Control组术后各时间点左肾T2弛豫时间和ADC值与术前比较差异无统计学意义（P〉0．05）。MRAC术后第1、7、28天，MRAC组他弛豫时间分别为（45．83±2．06）、（52．33±2．37）和（40．87±1．79）ms，均显著性高于Control组的（36．13±1．86）、（36．30±1．86）和（35．30±1．82）ms（P〈0．05）；MRAC组ADC值分别为（2．34±0．07）×10、（2．07±0．09）×10^-3和（2．40±0．08）×10^-3mm^2／s，均显著性低于Control组的（2．59±0．05）×10^-3、（2．67±0．06）×10^-3和（2．58±0．07）×10^-3mm^2／s（P〈0．05）。术后第90天，两组间12弛豫时间和ADC值比较，差异无统计学意义（P〉0．05）。Control组术后第1、90天声。降小球、肾小管及肾间质均未见异常；MRAC组术后第1天左肾广泛性肾小管水样变性，第90天左肾少数肾小管轻度水样变性，肾小球均未见特殊改变，肾间质均未见纤维组织增生及炎性细胞浸润。结论1、2弛豫时间和ADC可以无创性监测肾缺血再灌注损伤后病理过程的变化，有临床推广价值。

Objective To evaluate the value of the functional magnetic resonance imaging （MRI） techniques including T2 mapping and diffusion - weighted imaging （DWI） in characterizing renal pathology after renal ischemia - reperfusion injury in solitary - kidney porcine. Methods A total of 12 domestic pigs were randomized equally into 2 groups such as sham clanlping （control group） and main renal artery clamping （ MRAC group） according to the method of renal artery clamping. Each subject underwent right radical nephrectomy to create the condition of a solitary kidney. On the left kidney, sham clamping or MRAC was performed for 60 minutes. T2 relaxation time and apparent diffusion coefficient （ADC） were detected before surgery and at 4 time points thereafter （ day 1, 7, 28, 90） using a 3.0T magnet. Renal histology was determined on day 1, 90 after operation. Results In the control group, the T2 relaxation time and ADC of the left kidney were not significantly different from the preperative baseline value at every time point （ P 〉 0.05）. On day 1, 7, 28 after operation, T2 relaxation time of the MRAC group increased to （45.83 ± 2. 06）, （52. 33 ± 2. 37） and （40. 87 ± 1.79 ） ms, which were significantly higher than those of the control group [（36. 13 ± 1.86）, （36.30 ± 1.86）, （35.30 ±1.82） ms, P〈0.05] ; ADC values of the MRAC group decreased to （2.34±0.07） xl0-3, （2.07 ±0.09）×10^-3and （2.40±0.08） ×10^-3mm^2/s, which were significantly lower than those of the control group [ （ 2. 59 ±0. 05 ） x 10 - 3, （ 2. 67 ±0. 06 ） ×10^-3 and （2. 58 ±0. 07 ）×10^-3mm^2/s, p 〈 0. 05 ]. On day 90 after operation, there were no significantly differences on the T2 relaxation time and ADC values between the two groups （ P 〉 0. 05 ）. No pathological changes were found in control group on day 1,90 after operation, while the left kidney in the MRAC group experienced extensive tubular hydropic degeneration on day 1 and the tubular hydropic degeneration alleviated on day 90. Conclusion Measuring T2 relaxation time and ADC values through is an effective and noninvasive way to evaluate renal pathology after renal ischemia - reperfusion injury in solitary - kidney porcine. Thus, it may be useful in human clinical studies.