Toussaint J F, Southern J F, Fuster V, Kantor H L
Cardiac Unit, Massachusetts General Hospital, Boston 02114, USA.
Arterioscler Thromb Vasc Biol. 1995 Oct;15(10):1533-42.
We sought to determine whether 1H NMR images without chemical-shift selection can adequately characterize the components of human atheromatous arteries. NMR, as a nondestructive, biochemical imaging tool, has the potential to identify lipids in atherosclerotic plaques but has not yet produced detailed images of atheroma components. Using 1H NMR spectroscopy at 9.4 T, we examined microdissected components of diseased and normal arteries to determine water relaxation constants (T1 and T2) as well as the relative content of mobile lipid. Relaxation times were also measured at 1.5 and 4.7 T. Sections of arteries with atherosclerotic lesions of graded severity were imaged at 1.5 and 9.4 T. The contrast-to-noise ratio (CNR) was used to assess lesion conspicuity. In the atheromatous core, the water NMR signal predominates over that of lipid (lipid-to-water ratio, 0.11). At 9.4 T, T2 is 20.2 ms for the atheromatous core, 30.1 ms for the collagenous cap, and 29.5 ms for normal media. This results in a high CNR on T2-weighted (T2w) images for atheromatous core compared with the collagenous cap and normal media. A similar contrast was measured at lower field strength. Calcifications do not generate appreciable signal due to their low water content but can be detected on T1-weighted (T1w) images. The water T2 contrast allows discrimination of the atheromatous lipid core from collagenous regions. The combination of T1w and T2w sequences permits in vitro identification of the atheromatous core, collagenous cap, calcifications, media, adventitia, and perivascular fat. The discrimination of collagen fibers that overlie lipid deposits permits study of plaque protection and stability at all field strengths and may provide the basis for in vivo microscopy of human atherosclerosis.
我们试图确定未进行化学位移选择的1H NMR图像是否能够充分表征人类动脉粥样硬化动脉的组成成分。核磁共振（NMR）作为一种无损的生化成像工具，有潜力识别动脉粥样硬化斑块中的脂质，但尚未生成动脉粥样硬化成分的详细图像。我们使用9.4 T的1H NMR光谱，检查了患病动脉和正常动脉的显微切割成分，以确定水的弛豫常数（T1和T2）以及可移动脂质的相对含量。还在1.5 T和4.7 T下测量了弛豫时间。对具有不同严重程度动脉粥样硬化病变的动脉切片在1.5 T和9.4 T下进行成像。使用对比噪声比（CNR）来评估病变的清晰度。在动脉粥样硬化核心中，水的NMR信号比脂质信号占主导（脂质与水的比例为0.11）。在9.4 T时，动脉粥样硬化核心的T2为20.2 ms，胶原帽为30.1 ms，正常中膜为29.5 ms。这导致在T2加权（T2w）图像上，动脉粥样硬化核心与胶原帽和正常中膜相比具有较高的CNR。在较低场强下也测量到了类似的对比度。钙化由于其低含水量不会产生明显信号，但可在T1加权（T1w）图像上检测到。水的T2对比度可区分动脉粥样硬化脂质核心和胶原区域。T1w和T2w序列的组合允许在体外识别动脉粥样硬化核心、胶原帽、钙化、中膜、外膜和血管周围脂肪。对覆盖脂质沉积物的胶原纤维的区分允许在所有场强下研究斑块的保护和稳定性，并可能为人类动脉粥样硬化的体内显微镜检查提供基础。
