From the Departments of Radiology.
Rheumatology, and.
Invest Radiol. 2019 Feb;54(2):89-97. doi: 10.1097/RLI.0000000000000511.
The aim of this study was to test multiparametric magnetic resonance imaging including blood oxygen level-dependent (BOLD) imaging by T2* mapping, magnetic resonance elastography (MRE) by tomoelastography, and diffusion-weighted imaging (DWI) for detecting nephropathy in patients with lupus nephritis (LN).
Forty-one subjects (25 patients with LN and 16 age- and sex-matched healthy volunteers; LN: mean age, 47.3 ± 14.8 years; 22 female subjects; volunteers: mean age, 43.9 ± 11.6 years; 13 female subjects) were prospectively enrolled. The LN group was further divided into subgroups with normal (LN-nRF, GFR > 90 mL/min per 1.73 m) and compromised renal function (LN-cRF, GFR < 90 mL/min per 1.73 m). All subjects were examined by multifrequency MRE, BOLD imaging, and DWI, yielding shear wave speed (SWS; in meter per second), T2* relaxation times (in millisecond), and apparent diffusion coefficient (ADC; in millimeter square per second), respectively. Renal subregional analysis was performed for the medulla (ME), inner cortex (CoI), and outer cortex (CoO). Imaging markers were correlated to clinical parameters such as GFR and protein-to-urine creatinine ratio. Cutoffs and area under the receiver operating curve (AUROC) were computed to test diagnostic performances.
Compared with CoI and CoO, LN-nRF predominantly affects ME tissue (SWS: -7%, P < 0.01; T2*: +9%, P < 0.05; ADC: -5%, P = 0.27). Detection of LN-nRF was better with MRE compared with BOLD imaging and DWI (AUROC = 0.81, 0.76, not significant), whereas pairing MRE with T2* further increased diagnostic power (AUROC = 0.91). Disease progression was associated with reduction of SWS also in CoI (LN-nRF, 3.04 ± 0.38 m/s; LN-cRF, 2.60 ± 0.26 m/s; p = 0.013), allowing distinction of LN-nRF from LN-cRF (AUROC = 0.83). Diffusion-weighted imaging was only sensitive to LN-cRF in ME tissue (ADC, -12%; P < 0.05).
Lupus nephritis with normal renal function first arises in MRE and BOLD images within ME tissue, progressing to CoI tissue once renal function becomes impaired and diffusion of tissue water changes.
本研究旨在通过血氧水平依赖（BOLD）成像 T2*映射、磁共振剪切波弹性成像（MRE）的体元弹性成像、扩散加权成像（DWI）检测狼疮性肾炎（LN）患者的肾病。
前瞻性纳入 41 名受试者（25 名 LN 患者和 16 名年龄和性别匹配的健康志愿者；LN：平均年龄 47.3±14.8 岁；22 名女性；志愿者：平均年龄 43.9±11.6 岁；13 名女性）。LN 组进一步分为肾功能正常（LN-nRF，GFR＞90 mL/min/1.73 m）和肾功能受损（LN-cRF，GFR＜90 mL/min/1.73 m）亚组。所有受试者均接受多频 MRE、BOLD 成像和 DWI 检查，分别获得剪切波速度（SWS；米/秒）、T2*弛豫时间（毫秒）和表观扩散系数（ADC；毫米平方/秒）。对髓质（ME）、内皮质（CoI）和外皮质（CoO）进行肾脏亚区分析。将成像标志物与肾小球滤过率（GFR）和蛋白尿与尿肌酐比等临床参数相关联。计算截断值和受试者工作特征曲线（AUROC）下面积，以测试诊断性能。
与 CoI 和 CoO 相比，LN-nRF 主要影响 ME 组织（SWS：-7%，P＜0.01；T2*：+9%，P＜0.05；ADC：-5%，P=0.27）。与 BOLD 成像和 DWI 相比，MRE 对 LN-nRF 的检测效果更好（AUROC=0.81、0.76，无显著差异），而将 MRE 与 T2* 结合可进一步提高诊断能力（AUROC=0.91）。疾病进展与 CoI 中 SWS 降低有关（LN-nRF：3.04±0.38 m/s；LN-cRF：2.60±0.26 m/s；P=0.013），从而可以区分 LN-nRF 和 LN-cRF（AUROC=0.83）。DWI 仅在 ME 组织中对 LN-cRF 敏感（ADC：-12%；P＜0.05）。
在 ME 组织的 MRE 和 BOLD 图像中首先出现肾功能正常的狼疮性肾炎，一旦肾功能受损，组织水扩散发生变化，就会进展到 CoI 组织。
