Stacy M R, Qiu M, Papademetris X, Caracciolo C M, Constable R T, Sinusas A J
Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.
Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT, USA.
Eur J Vasc Endovasc Surg. 2016 May;51(5):743-9. doi: 10.1016/j.ejvs.2016.02.008. Epub 2016 Mar 9.
OBJECTIVE/BACKGROUND: To evaluate the feasibility and repeatability of applying blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) in the feet to quantify regional dynamic changes in tissue oxygenation during proximal cuff occlusion and reactive hyperemia.
Ten healthy male subjects underwent BOLD and T1-weighted imaging of the feet on two separate occasions, using a 3-T scanner. Dynamic changes in BOLD signal intensity were assessed before and during proximal cuff occlusion of the thigh and during reactive hyperemia, and BOLD time course data were evaluated for the time-to-half ischemic minimum, minimum ischemic value, peak hyperemic value, time-to-peak hyperemia, time-to-half peak hyperemia, and end value. T1-weighted images were used for segmentation of volumes of interest (VOI) in anatomical regions of the foot (heel, toes, dorsal foot, medial and lateral plantar foot). Repeatability of vascular responses was assessed for each foot VOI using semiautomated image registration and quantification of serial BOLD images.
The heel VOI demonstrated a significantly higher peak hyperemic response, expressed as percent change from baseline BOLD signal intensity, compared with all other VOIs of the foot (heel, 7.4 ± 1.2%; toes, 5.6 ± 0.8%; dorsal foot, 5.7 ± 1.6%; medial plantar, 5.6 ± 1.7%; lateral plantar, 5.6 ± 1.5% [p < .05]). Additionally, the lateral plantar VOI had a significantly lower terminal signal intensity value (i.e., end value) when compared with all foot VOIs (p < .05). BOLD MRI was repeatable between visits in all foot VOIs, with no significant differences between study visits for any of the evaluated functional indices.
BOLD MRI offers a repeatable technique for volumetric assessment of regional foot tissue oxygenation. Future application of BOLD imaging in the feet of patients with peripheral vascular disease may permit serial evaluation of regional tissue oxygenation and allow for improved assessment of therapeutic interventions targeting specific sites of the foot.
目的/背景：评估应用足部血氧水平依赖（BOLD）磁共振成像（MRI）来量化近端袖带阻断和反应性充血期间组织氧合的区域动态变化的可行性和可重复性。
10名健康男性受试者在两个不同时间使用3-T扫描仪对足部进行BOLD和T1加权成像。在大腿近端袖带阻断前、阻断期间以及反应性充血期间评估BOLD信号强度的动态变化，并评估BOLD时间历程数据的半缺血最小值时间、最小缺血值、充血峰值、充血峰值时间、半充血峰值时间和终末值。T1加权图像用于分割足部解剖区域（足跟、脚趾、足背、足底内侧和外侧）的感兴趣体积（VOI）。使用半自动图像配准和连续BOLD图像定量评估每个足部VOI血管反应的可重复性。
与足部所有其他VOI相比，足跟VOI表现出显著更高的充血峰值反应，以相对于基线BOLD信号强度的百分比变化表示（足跟，7.4±1.2%；脚趾，5.6±0.8%；足背，5.7±1.6%；足底内侧，5.6±1.7%；足底外侧，5.6±1.5%[p<.05]）。此外，与所有足部VOI相比，足底外侧VOI的终末信号强度值（即终末值）显著更低（p<.05）。所有足部VOI在不同检查之间BOLD MRI具有可重复性，对于任何评估的功能指标，研究检查之间均无显著差异。
BOLD MRI为区域足部组织氧合的容积评估提供了一种可重复的技术。BOLD成像在周围血管疾病患者足部的未来应用可能允许对区域组织氧合进行系列评估，并有助于改进针对足部特定部位的治疗干预评估。
