Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, No. 160, Pujian Rd, Shanghai, 200127, China.
Department of Vascular Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
J Cardiovasc Magn Reson. 2018 Mar 19;20(1):18. doi: 10.1186/s12968-018-0441-3.
Noninvasive cardiovascular magnetic resonance (CMR) techniques including arterial spin labeling (ASL), blood oxygenation level-dependent (BOLD), and intravoxel incoherent motion (IVIM), are capable of measuring tissue perfusion-related parameters. We sought to evaluate and compare these three CMR techniques in characterizing skeletal muscle perfusion in lower extremities and to investigate their abilities to diagnose and assess the severity of peripheral arterial disease (PAD).
Fifteen healthy young subjects, 14 patients with PAD, and 10 age-matched healthy old subjects underwent ASL, BOLD, and IVIM CMR perfusion imaging. Healthy young and healthy old participants were subjected to a cuff-induced ischemia experiment with pressures of 20 mmHg and 40 mmHg above systolic pressure during imaging. Perfusion-related metrics, including blood flow, T2* relaxation time, perfusion fraction f, diffusion coefficient D, and pseudodiffusion coefficient D*, were measured in the anterior, lateral, soleus, and gastrocnemius muscle groups. Friedman, Mann-Whitney, Wilcoxon signed rank, and Spearman rank correlation tests were used for statistical analysis.
In cases of significant differences determined by the Friedman test (P < 0.05), blood flow, T2*, and D values gradually decreased, while f values showed a tendency to increase in healthy subjects under cuff compression. No significant correlations were found among the ASL, BOLD, and IVIM parameters (all P > 0.05). Blood flow and T2* values showed significant positive correlations with transcutaneous oxygen pressure measurements (ρ = 0.465 and 0.522, respectively; both P ≤ 0.001), while f values showed a significant negative correlation in healthy young subjects (ρ = - 0.351; P = 0.018). T2* was independent of age in every muscle group. T2* values were significantly decreased in PAD patients compared with healthy old subjects and severe PAD patients compared with mild-to-moderate PAD patients (all P < 0.0125). Significant correlations were found between T2* and ankle-brachial index values in all muscle groups in PAD patients (ρ = 0.644-0.837; all P < 0.0125). Other imaging parameters failed to show benefits towards the diagnosis and disease severity evaluation of PAD.
ASL, BOLD, and IVIM provide complementary information regarding tissue perfusion. Compared with ASL and IVIM, BOLD may be a more reliable technique for assessing PAD in the resting state and could thus be applied together with angiography in clinical studies as a tool to comprehensively assess microvascular and macrovascular properties in PAD patients.
非侵入性心血管磁共振（CMR）技术，包括动脉自旋标记（ASL）、血氧水平依赖（BOLD）和体素内不相干运动（IVIM），能够测量组织灌注相关参数。我们旨在评估和比较这三种 CMR 技术在下肢骨骼肌灌注中的特征，并研究它们在诊断和评估外周动脉疾病（PAD）严重程度方面的能力。
15 名健康年轻受试者、14 名 PAD 患者和 10 名年龄匹配的健康老年受试者接受了 ASL、BOLD 和 IVIM CMR 灌注成像。健康年轻和健康老年受试者在成像过程中接受袖带引起的缺血实验，压力分别高于收缩压 20mmHg 和 40mmHg。在股四头肌、外侧肌、比目鱼肌和腓肠肌组中测量灌注相关指标，包括血流、T2弛豫时间、灌注分数 f、扩散系数 D 和假性扩散系数 D。采用 Friedman、Mann-Whitney、Wilcoxon 符号秩和检验和 Spearman 秩相关检验进行统计学分析。
在 Friedman 检验确定有显著差异的情况下（P<0.05），在袖带压迫下，健康受试者的血流、T2和 D 值逐渐降低，而 f 值呈上升趋势。ASL、BOLD 和 IVIM 参数之间没有发现显著相关性（均 P>0.05）。血流和 T2值与经皮氧分压测量值呈显著正相关（ρ=0.465 和 0.522，均 P≤0.001），而健康年轻受试者的 f 值呈显著负相关（ρ=-0.351；P=0.018）。T2在每个肌肉群中均与年龄无关。与健康老年受试者相比，PAD 患者的 T2值显著降低，与轻中度 PAD 患者相比，严重 PAD 患者的 T2值显著降低（均 P<0.0125）。在 PAD 患者的所有肌肉群中，T2值与踝臂指数值之间均存在显著相关性（ρ=0.644-0.837；均 P<0.0125）。其他成像参数未能在 PAD 的诊断和疾病严重程度评估方面提供获益。
ASL、BOLD 和 IVIM 提供了关于组织灌注的互补信息。与 ASL 和 IVIM 相比，BOLD 可能是一种更可靠的评估静息状态下 PAD 的技术，因此可以与血管造影一起应用于临床研究，作为一种全面评估 PAD 患者微血管和大血管特性的工具。
