Jiang Kai, Fang Yiyuan, Ferguson Christopher M, Tang Hui, Mishra Prasanna K, Macura Slobodan I, Lerman Lilach O
Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.
Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA.
J Magn Reson Imaging. 2020 Sep 17. doi: 10.1002/jmri.27370.
Renal fibrosis is a common pathway in tubulointerstitial injury and a major determinant of renal insufficiency. Collagen deposition, a key feature of renal fibrosis, may serve as an imaging biomarker to differentiate scarred from healthy kidneys.
To test the feasibility of using quantitative magnetization transfer (qMT), which assesses tissue macromolecule content, to measure renal fibrosis.
Prospective.
Fifteen 129S1 mice were studied 4 weeks after either sham (n = 7) or unilateral renal artery stenosis (RAS, n = 8) surgeries.
FIELD STRENGTH/SEQUENCE: Magnetization transfer (MT)-weighted images were acquired at 16.4T using an MT-prepared fast-low-angle-shot sequence. Renal B, B, and T maps were also acquired, using a dual-echo gradient echo, an actual flip angle, and inversion recovery method, respectively.
A two-pool model was used to estimate the bound water fraction (f) and other tissue imaging biomarkers. Masson's trichrome staining was subsequently performed ex vivo to evaluate renal fibrosis.
Comparisons of renal parameters between sham and RAS were performed using independent samples t-tests. Pearson's correlation was conducted to investigate the relationship between renal fibrosis by histology and the qMT-derived bound pool fraction f.
The two-pool model provided accurate fittings of measured MT signal. The qMT-derived f of RAS kidneys was significantly increased compared to sham in all kidney zones (renal cortex [CO], 7.6 ± 2.4% vs. 4.6 ± 0.6%; outer medulla [OM], 8.2 ± 4.2% vs. 4.2 ± 0.9%; inner medulla [IM] + P, 5.8 ± 1.6% vs. 2.9 ± 0.6%, all P < 0.05). Measured f correlated well with histological fibrosis in all kidney zones (CO, Pearson's correlation coefficient r = 0.95; OM, r = 0.93; IM + P, r = 0.94, all P < 0.05).
The bound pool fraction f can be quantified using qMT at 16.4T in murine kidneys, increases significantly in fibrotic RAS kidneys, and correlates well with fibrosis by histology. Therefore, qMT may constitute a valuable tool for measuring renal fibrosis in RAS.
1 TECHNICAL EFFICACY STAGE: 3.
肾纤维化是肾小管间质损伤的常见途径，也是肾功能不全的主要决定因素。胶原沉积作为肾纤维化的关键特征，可作为一种成像生物标志物，用于区分瘢痕肾和健康肾。
测试使用定量磁化传递（qMT）评估组织大分子含量来测量肾纤维化的可行性。
前瞻性研究。
对15只129S1小鼠进行研究，这些小鼠在假手术（n = 7）或单侧肾动脉狭窄（RAS，n = 8）手术后4周接受检查。
场强/序列：使用MT准备的快速低角度激发序列在16.4T采集磁化传递（MT）加权图像。还分别使用双回波梯度回波、实际翻转角和反转恢复方法采集肾脏的B、B和T图。
采用双池模型估计结合水分数（f）和其他组织成像生物标志物。随后进行离体Masson三色染色以评估肾纤维化。
使用独立样本t检验比较假手术组和RAS组的肾脏参数。采用Pearson相关性分析来研究组织学上的肾纤维化与qMT衍生的结合池分数f之间的关系。
双池模型对测量的MT信号提供了准确拟合。与假手术组相比，RAS组肾脏所有区域的qMT衍生f均显著增加（肾皮质[CO]，7.6±2.4%对4.6±0.6%；外髓质[OM]，8.2±4.2%对4.2±0.9%；内髓质[IM]+肾盂，5.8±1.6%对2.9±0.6%，所有P<0.05）。在所有肾脏区域，测量的f与组织学纤维化均具有良好的相关性（CO，Pearson相关系数r = 0.95；OM，r = 0.93；IM+P，r = 0.94，所有P<0.05）。
结合池分数f可在16.4T下使用qMT对小鼠肾脏进行量化，在纤维化RAS肾脏中显著增加，且与组织学纤维化具有良好的相关性。因此，qMT可能是测量RAS中肾纤维化的一种有价值的工具。
1 技术效能阶段：3。
