Saam Tobias, Underhill Hunter R, Chu Baocheng, Takaya Norihide, Cai Jianming, Polissar Nayak L, Yuan Chun, Hatsukami Thomas S
Department of Clinical Radiology, University of Munich, Grosshadern Campus, Munich, Germany.
J Am Coll Cardiol. 2008 Mar 11;51(10):1014-21. doi: 10.1016/j.jacc.2007.10.054.
Via magnetic resonance imaging (MRI), we sought to determine the prevalence of atherosclerotic American Heart Association type VI lesions (AHA-LT6) (lesions with luminal surface defect, hemorrhage/thrombus, or calcified nodule) in carotid arteries that represented all categories of stenosis as measured by duplex ultrasound.
Arterial stenosis alone has been shown to be a poor predictor of cardiovascular events. Autopsy studies suggest that features associated with AHA-LT6 lesions, rather than the degree of luminal narrowing, characterize the high-risk plaque.
A total of 192 subjects underwent bilateral carotid artery magnetic resonance imaging (MRI) scans at 1.5T after evaluation with ultrasound to determine stenosis. After excluding arteries with a previous endarterectomy, poor image quality, or missing ultrasound data, there were 175 patients with 260 arteries available for analysis. The AHA lesion type was determined by the consensus opinion of 2 experienced carotid MRI reviewers.
In total, 96 of 260 (37.0%) arteries had >or=1 location with AHA-LT6. Of the arteries with AHA-LT6, 84.4% had hemorrhage, 45.8% had a ruptured fibrous cap, and 14.6% showed other type of complications. Prevalence of AHA-LT6 was an increasing sequence of 8.1% in the 37 arteries with 1% to 15% stenosis, 21.7% in the 60 arteries with 16% to 49% stenosis, 36.8% in the 114 arteries with 50% to 79% stenosis, and 77.6% in the 49 arteries with 80% to 99% stenosis.
Complicated AHA-LT6 are frequently found in arteries with <or=50% stenosis. These findings indicate that complex lesions develop in a substantial number of arteries in the absence of high-grade stenosis. Ongoing prospective studies will determine the predictive value of vulnerable plaque features, as visualized by MRI, for risk of subsequent ischemic events.
通过磁共振成像（MRI），我们试图确定在经双功超声测量的代表所有狭窄类别的颈动脉中，动脉粥样硬化美国心脏协会VI型病变（AHA-LT6）（具有管腔表面缺陷、出血/血栓或钙化结节的病变）的患病率。
单独的动脉狭窄已被证明是心血管事件的不良预测指标。尸检研究表明，与AHA-LT6病变相关的特征而非管腔狭窄程度，才是高危斑块的特征。
共有192名受试者在经超声评估以确定狭窄后，接受了1.5T的双侧颈动脉磁共振成像（MRI）扫描。在排除曾接受内膜切除术、图像质量差或缺少超声数据的动脉后，有175名患者的260条动脉可供分析。AHA病变类型由2名经验丰富的颈动脉MRI阅片者达成的共识意见确定。
总共260条动脉中有96条（37.0%）有一处或多处AHA-LT6病变。在有AHA-LT6病变的动脉中，84.4%有出血，45.8%有纤维帽破裂，14.6%显示其他类型的并发症。AHA-LT6的患病率按狭窄程度递增顺序排列：在37条狭窄1%至15%的动脉中为8.1%，在60条狭窄16%至49%的动脉中为21.7%，在114条狭窄50%至79%的动脉中为36.8%，在49条狭窄80%至99%的动脉中为77.6%。
在狭窄程度≤50%的动脉中经常发现复杂的AHA-LT6病变。这些发现表明，在没有高度狭窄的情况下，大量动脉中会出现复杂病变。正在进行的前瞻性研究将确定MRI显示的易损斑块特征对后续缺血事件风险的预测价值。
