Stroke：颈动脉外膜灌注成像有助研究斑块发病机理

活检研究提示斑块内出血与血管滋养管存在相关，后者主要来自外膜。颈动脉外膜血管滋养管能够通过动态增强MRI以估计灌注参数得以确定。为此，美国华盛顿大学影像科的Jie Sun与北京医院影像科的Yan Song使用动态增强MRI进行了一项研究。研究结果在线发表在2013年3月7日的Stroke杂志上。研究结果显示：外膜和斑块内出血存在独立的生理病理联系。它们的联系在于外膜血管滋养管的微结构。外膜灌注成像可能有助研究斑块的发病机理，但需要通过前瞻性的研究进行更深入的探讨。
研究人员对有脑缺血症状伴病灶同侧颈动脉斑块的患者进行双侧颈动脉MRI检查，检查包括多个增强序列（以检测斑块内出血）和动态增强MRI序列（以确定外膜灌注）。进行动态增强MRI时间序列的Kinetic模式以估计外膜vp（比例血浆容量，反映局部血供）和Ktrans（转移常数，反映血管表面积和通透性）。
研究结果显示：纳入27位患者(22位为男性，平均年龄69±10岁) ，50条动脉中获得外膜灌注参数。斑块内出血与显著较高的外膜Ktrans值相关(0.142±0.042对比0.112±0.029 min−1;P<0.001) ，但与 vp值无关 (0.163±0.064 vs 0.149±0.062;P=0.338)。在校正缺血症状的情况、颈动脉狭窄程度和其他混杂因素后，这种相关性仍然存在。
该研究显示：外膜和斑块内出血存在独立的生理病理联系。它们的联系在于外膜血管滋养管的微结构。外膜灌注成像可能有助研究斑块的发病机理，但需要通过前瞻性的研究进行更深入的探讨。

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Adventitial perfusion and intraplaque hemorrhage: a dynamic contrast-enhanced MRI study in the carotid artery.
BACKGROUND AND PURPOSE
Autopsy studies have suggested a relationship between intraplaque hemorrhage (IPH) and vasa vasorum, which arise primarily from the adventitia. Adventitial vasa vasorum can be characterized in the carotid arteries by estimating perfusion parameters via dynamic contrast-enhanced MRI. The purpose of this investigation was to use dynamic contrast-enhanced MRI to test in vivo in a clinical population whether adventitial perfusion, indicative of vasa vasorum microstructure, is associated with IPH.
METHODS
Symptomatic patients with carotid plaque ipsilateral to the ischemic event underwent bilateral carotid artery MRI examination, which included multicontrast sequences for detecting IPH and a dynamic contrast-enhanced MRI sequence for characterizing adventitial perfusion. Kinetic modeling of the dynamic contrast-enhanced MRI time series was performed to estimate adventitial vp (fractional plasma volume, reflecting local blood supply) and K(trans) (transfer constant, reflecting vessel surface area, and permeability).
RESULTS
From the 27 patients (22 men; 69±10 years of age) recruited, adventitial perfusion parameters were obtained in 50 arteries. The presence of IPH was associated with a significantly higher value in adventitial K(trans) (0.142±0.042 vs 0.112±0.029 min(-1); P<0.001) but not in vp (0.163±0.064 vs 0.149±0.062; P=0.338). This relationship remained after adjusting for symptomatic status, degree of stenosis, and other confounding factors.
CONCLUSIONS
This study demonstrated an independent pathophysiological link between the adventitia and IPH and related it to the microstructure of adventitial vasa vasorum. Adventitial perfusion imaging may be useful in studying plaque pathogenesis, but further examination through prospective studies is needed.