Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, Germany.
Invest Radiol. 2013 Mar;48(3):140-4. doi: 10.1097/RLI.0b013e318277bfe3.
The purpose of the present study was to explore the correlation between diffusion parameters assessed by biexponential analysis and the tissue perfusion measured by arterial spin labeling (ASL) imaging in renal allografts.
Seventeen recipients of renal allograft (11 men and 6 women; mean [SD] age, 53.6 [14.1] years) were included in this study. For diffusion-weighted imaging, a paracoronal echo-planar imaging sequence was acquired with 16 b values (range, b = 0-750 s/mm²) and 6 averages at 1.5 T. For the quantitative assessment of transplanted kidney perfusion, a flow-sensitive alternating inversion recovery true fast imaging with steady precession-ASL technique was applied. No respiratory gating was used. For quantitative analysis, region of interest measurements were performed on parameter maps. The Spearman correlation coefficients were calculated to determine the association between mean serum creatinine levels, estimated glomerular filtration rate, the apparent diffusion coefficient (ADC) of pure diffusion, the ADC of pseudodiffusion, the monoexponential ADC, the fraction of pseudodiffusion, and the tissue perfusion ASL values.
In the renal cortex, the fraction of pseudodiffusion was 17.4% ± 4.0%, the apparent diffusion coefficient of pure diffusion was 160.7 ± 15.0 × 10⁻⁵ mm²/s, the monoexponential ADC was 193.2 ± 16.7 × 10⁻⁵ mm²/s, and the ADC of pseudodiffusion was 1421.0 ± 237.7 × 10⁻⁵ mm²/s. Mean cortical perfusion of renal allografts, as assessed with ASL imaging, was 247.2 ± 75.0 mL/100 g/min. There was a significant correlation between ASL perfusion and the fraction of pseudodiffusion (r = 0.68; P < 0.005) but not with the other diffusion coefficients. Both ASL perfusion and the fraction of pseudodiffusion exhibited a significant correlation with serum creatinine levels (r = 0.51 and r= 0.53, respectively; P < 0.05) and estimated glomerular filtration rate (r = 0.63 and r = 0.54, respectively; P < 0.05).
This is the first study that shows a significant correlation between renal allograft perfusion, as assessed with ASL perfusion measurements, and the fraction of pseudodiffusion derived from biexponential diffusion-weighted imaging measurements.
本研究旨在探讨双指数分析评估的扩散参数与肾移植组织的动脉自旋标记（ASL）成像测量的灌注之间的相关性。
本研究纳入了 17 例接受肾移植的受者（11 名男性，6 名女性；平均[标准差]年龄，53.6[14.1]岁）。采用矢状面 echo-planar 成像序列进行扩散加权成像，共采集 16 个 b 值（范围，b=0-750 s/mm²）和 6 个平均 b 值，采集时使用 1.5 T 磁场。采用流量敏感交替反转恢复真正快速成像稳态进动 ASL 技术对移植肾灌注进行定量评估。未使用呼吸门控。进行定量分析时，在参数图上进行感兴趣区测量。使用 Spearman 相关系数来确定平均血清肌酐水平、估算肾小球滤过率、纯扩散的表观扩散系数（ADC）、假性扩散的 ADC、单指数 ADC、假性扩散分数和组织灌注 ASL 值之间的相关性。
在肾皮质中，假性扩散分数为 17.4%±4.0%，纯扩散的 ADC 为 160.7±15.0×10⁻⁵mm²/s，单指数 ADC 为 193.2±16.7×10⁻⁵mm²/s，假性扩散的 ADC 为 1421.0±237.7×10⁻⁵mm²/s。使用 ASL 成像评估的肾移植皮质平均灌注为 247.2±75.0mL/100g/min。ASL 灌注与假性扩散分数之间存在显著相关性（r=0.68；P<0.005），但与其他扩散系数无相关性。ASL 灌注和假性扩散分数均与血清肌酐水平（r=0.51 和 r=0.53，均 P<0.05）和估算肾小球滤过率（r=0.63 和 r=0.54，均 P<0.05）呈显著相关。
本研究首次表明，肾移植组织的灌注（通过 ASL 灌注测量）与双指数扩散加权成像测量得到的假性扩散分数之间存在显著相关性。
