正常及肿瘤旁肾组织的肾血流和微观结构各向异性（REFMAP）MRI
REnal Flow and Microstructure AnisotroPy (REFMAP) MRI in Normal and Peritumoral Renal Tissue.
机构信息
New York University School of Medicine, New York, New York, USA.
Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.
出版信息
J Magn Reson Imaging. 2018 Jul;48(1):188-197. doi: 10.1002/jmri.25940. Epub 2018 Jan 13.
BACKGROUND
Diffusion-weighted imaging (DWI) provides insight into the pathophysiology underlying renal dysfunction. Variants of DWI include intravoxel incoherent motion (IVIM), which differentiates between microstructural diffusion and vascular or tubular flow, and diffusion tensor imaging (DTI), which quantifies diffusion directionality.
PURPOSE
To investigate the reproducibility of joint IVIM-DTI and compare controls to presurgical renal mass patients.
STUDY TYPE
Prospective cross-sectional.
SUBJECTS
Thirteen healthy controls and ten presurgical renal mass patients were scanned. Ten controls were scanned twice to investigate reproducibility.
FIELD STRENGTH/SEQUENCE: Subjects were scanned on a 3T system using 10 b-values and 20 diffusion directions for IVIM-DTI in a study approved by the local Institutional Review Board.
ASSESSMENT
Retrospective coregistration and measurement of joint IVIM-DTI parameters were performed.
STATISTICAL ANALYSIS
Parameter reproducibility was defined as intraclass correlation coefficient (ICC) >0.7 and coefficient of variation (CV) <30%. Patient data were stratified by lesion side (contralateral/ipsilateral) for comparison with controls. Corticomedullary differentiation was evaluated.
RESULTS
In controls, the reproducible subset of REnal Flow and Microstructure AnisotroPy (REFMAP) parameters had average ICC = 0.82 and CV = 7.5%. In renal mass patients, medullary fractional anisotropy (FA) was significantly lower than in controls (0.227 ± 0.072 vs. 0.291 ± 0.044, P = 0.016 for the kidney contralateral to the mass and 0.228 ± 0.070 vs. 0.291 ± 0.044, P = 0.018 for the kidney ipsilateral). In the kidney ipsilateral to the mass, cortical D was significantly higher than in controls (P = 0.012). Conversely, medullary D was significantly lower in contralateral than ipsilateral kidneys (P = 0.027) and normal controls (P = 0.044).
DATA CONCLUSION
REFMAP-MRI parameters provide unique information regarding renal dysfunction. In presurgical renal mass patients, directional flow changes were noted that were not identified with IVIM analysis alone. Both contralateral and ipsilateral kidneys in patients show reductions in structural diffusivities and anisotropy, while flow metrics showed opposing changes in contralateral vs. ipsilateral kidneys.
LEVEL OF EVIDENCE
2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.
背景
弥散加权成像（DWI）提供了对肾功能障碍的病理生理学的深入了解。DWI 的变体包括体素内不相干运动（IVIM），它区分微观结构扩散和血管或管状流动，以及扩散张量成像（DTI），它量化扩散方向。
目的
研究联合 IVIM-DTI 的可重复性，并将对照与术前肾肿块患者进行比较。
研究类型
前瞻性横断面研究。
受试者
13 名健康对照者和 10 名术前肾肿块患者接受了扫描。10 名对照者接受了两次扫描以研究可重复性。
磁场强度/序列：受试者在获得当地机构审查委员会批准的研究中，使用 3T 系统对 10 个 b 值和 20 个扩散方向进行了 IVIM-DTI 扫描。
评估
回顾性核心配准和联合 IVIM-DTI 参数的测量。
统计分析
参数可重复性定义为组内相关系数（ICC）>0.7 和变异系数（CV）<30%。根据病变侧（对侧/同侧）对患者数据进行分层，以与对照组进行比较。评估皮质髓质分化。
结果
在对照组中，REFMAP 参数的可重复性子集的平均 ICC=0.82，CV=7.5%。在肾肿块患者中，髓质各向异性分数（FA）明显低于对照组（0.227±0.072 vs. 0.291±0.044，P=0.016 对肿块对侧的肾脏和 0.228±0.070 vs. 0.291±0.044，P=0.018 对肿块同侧的肾脏）。在肿块同侧的肾脏中，皮质 D 明显高于对照组（P=0.012）。相反，对侧肾脏的髓质 D 明显低于同侧肾脏（P=0.027）和正常对照组（P=0.044）。
数据结论
REFMAP-MRI 参数提供了有关肾功能障碍的独特信息。在术前肾肿块患者中，除了 IVIM 分析之外，还发现了定向流变化。患者的对侧和同侧肾脏均显示结构扩散率和各向异性降低，而流测量值显示对侧与同侧肾脏的变化相反。
证据水平
2 技术功效：第 2 阶段 J. 磁共振成像 2018 年。
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