Medical Department I, University Hospital Marien Hospital Herne, Ruhr-University of Bochum, Bochum, Germany.
Department of Radiology, University Hospital Marien Hospital Herne, Ruhr-University of Bochum, Bochum, Germany.
Kidney Blood Press Res. 2017;42(6):1078-1089. doi: 10.1159/000485600. Epub 2017 Dec 4.
BACKGROUND/AIMS: To date, there is no imaging technique to assess tubular function in vivo. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) measures tissue oxygenation based on the transverse relaxation rate (R2*). The present study investigates whether BOLD MRI can assess tubular function using a tubule-specific pharmacological maneuver.
Cross sectional study with 28 participants including 9 subjects with ATN-induced acute kidney injury (AKI), 9 healthy controls, and 10 subjects with nephron sparing tumor resection (NSS) with clamping of the renal artery serving as a model of ischemia/reperfusion (I/R)-induced subclinical ATN (median clamping time 15 min, no significant decrease of eGFR, p=0.14). BOLD MRI was performed before and 5, 7, and 10 min after intravenous administration of 40 mg furosemide.
Urinary neutrophil gelatinase-associated lipocalin was significantly higher in ATN-induced AKI and NSS subjects than in healthy controls (p=0.03 and p=0.01, respectively). Before administration of furosemide, absolute medullary R2*, cortical R2*, and medullary/cortical R2* ratio did not significantly differ between ATN-induced AKI vs. healthy controls and between NSS-I/R vs. contralateral healthy kidneys (p>0.05 each). Furosemide led to a significant decrease in the medullary and cortical R2* of healthy subjects and NSS contralateral kidneys (p<0.05 each), whereas there was no significant change of R2* in ATN-induced AKI and the NSS-I/R kidneys (p>0.05 each).
BOLD-MRI is able to detect even mild tubular injury but necessitates a tubule-specific pharmacological maneuver, e.g. blocking the Na+-K+-2Cl- transporter by furosemide.
背景/目的：迄今为止，尚无评估体内管状功能的影像学技术。基于横向弛豫率（R2*）的血氧水平依赖磁共振成像（BOLD MRI）可测量组织氧合。本研究旨在探讨 BOLD MRI 是否可通过特定于管状的药物操作来评估管状功能。
一项横断面研究，共纳入 28 名参与者，包括 9 名急性肾损伤（AKI）所致急性肾小管坏死（ATN）患者、9 名健康对照者和 10 名因保肾肿瘤切除术（NSS）而夹闭肾动脉的患者（肾动脉夹闭中位时间 15 分钟，eGFR 无显著下降，p=0.14）。静脉注射 40mg 呋塞米前、后 5、7 和 10 分钟进行 BOLD MRI。
与健康对照者相比，ATN 所致 AKI 和 NSS 患者的尿中性粒细胞明胶酶相关脂质运载蛋白显著升高（p=0.03 和 p=0.01）。呋塞米给药前，ATN 所致 AKI 与健康对照组之间、NSS 缺血/再灌注（I/R）与对侧健康肾脏之间的绝对髓质 R2*、皮质 R2和髓质/皮质 R2比值无显著差异（p>0.05）。呋塞米可显著降低健康者和 NSS 对侧肾脏的髓质和皮质 R2*（p<0.05），但 ATN 所致 AKI 和 NSS I/R 肾脏的 R2*无显著变化（p>0.05）。
BOLD-MRI 能够检测到即使是轻度的管状损伤，但需要特定于管状的药物操作，例如通过呋塞米阻断 Na+-K+-2Cl-转运体。
