目的:本研究旨在探讨超高b值弥散加权成像(ubDWI)评价兔肾动脉狭窄(RAS)所致肾纤维化(RF)的可行性。
方法:32只兔子接受左RAS手术,而8只兔子接受了假手术。所有兔子均进行了UbDWI(b=0-4500s/mm2)。标准表观扩散系数(ADCst),分子扩散系数(D),灌注分数(f),术前以及术后第2、4和6周纵向评估灌注相关扩散系数(D*)和超高表观扩散系数(ADCuh)。通过病理检查确定间质纤维化程度以及水通道蛋白(AQP)1和AQP2的表达。
结果:在狭窄的肾脏中,ADCst,D,f,与基线相比,肾实质的ADCuh值显着降低(均P<0.05),而RAS诱导后D*值显着增加(P<0.05)。ADCst,D,D*,f与间质纤维化以及AQP1和AQP2的表达弱相关。此外,ADC与间质纤维化呈负相关(ρ=-0.782,P<0.001),与AQP1和AQP2表达呈正相关(分别为ρ=0.794,P<0.001和ρ=0.789,P<0.001)。
结论:具有超高b值的扩散加权成像显示了无创性评估单侧RAS兔RF进展的潜力。从ubDWI导出的ADCuh可以反映AQPs在RF中的表达。
OBJECTIVE: This study aimed to investigate the feasibility of diffusion-weighted imaging with ultrahigh b values ( ub DWI) for the evaluation of renal fibrosis (RF) induced by renal artery stenosis (RAS) in a rabbit model.
METHODS: Thirty-two rabbits underwent left RAS operation, whereas 8 rabbits received sham surgery. All rabbits underwent ub DWI ( b = 0-4500 s/mm 2 ). The standard apparent diffusion coefficient (ADC st ), molecular diffusion coefficient ( D ), perfusion fraction ( f ), perfusion-related diffusion coefficient ( D *) and ultrahigh apparent diffusion coefficient (ADC uh ) were longitudinally assessed before operation and at weeks 2, 4, and 6 after operation. The degree of interstitial fibrosis and the expression of aquaporin (AQP) 1 and AQP2 were determined through pathological examination.
RESULTS: In the stenotic kidney, the ADC st , D , f , and ADC uh values of the renal parenchyma significantly decreased compared with those at baseline (all P < 0.05), whereas the D * values significantly increased after RAS induction ( P < 0.05). The ADC st , D , D *, and f were weakly to moderately correlated with interstitial fibrosis as well as with the expression of AQP1 and AQP2. Furthermore, the ADC uh negatively correlated with interstitial fibrosis ( ρ = -0.782, P < 0.001) and positively correlated with AQP1 and AQP2 expression ( ρ = 0.794, P < 0.001, and ρ = 0.789, P < 0.001, respectively).
CONCLUSIONS: Diffusion-weighted imaging with ultrahigh b values shows the potential for noninvasive assessment of the progression of RF in rabbits with unilateral RAS. The ADC uh derived from ub DWI could reflect the expression of AQPs in RF.