van der Kolk A G, Zwanenburg J J M, Denswil N P, Vink A, Spliet W G M, Daemen M J A P, Visser F, Klomp D W J, Luijten P R, Hendrikse J
Radiology (A.G.v.d.K., J.J.M.Z., F.V., D.W.J.K., P.R.L., J.H.)
Radiology (A.G.v.d.K., J.J.M.Z., F.V., D.W.J.K., P.R.L., J.H.) Image Sciences Institute (J.J.M.Z.), University Medical Center Utrecht, Utrecht, the Netherlands.
AJNR Am J Neuroradiol. 2015 Apr;36(4):694-701. doi: 10.3174/ajnr.A4178. Epub 2014 Dec 4.
Several studies have attempted to characterize intracranial atherosclerotic plaques by using MR imaging sequences. However, dedicated validation of these sequences with histology has not yet been performed. The current study assessed the ability of ultra-high-resolution 7T MR imaging sequences with different image contrast weightings to image plaque components, by using histology as criterion standard.
Five specimens of the circle of Wills were imaged at 7T with 0.11 × 0.11 mm in-plane-resolution proton attenuation-, T1-, T2-, and T2*-weighted sequences (through-plane resolution, 0.11-1 mm). Tissue samples from 13 fiducial-marked locations (per specimen) on MR imaging underwent histologic processing and atherosclerotic plaque classification. Reconstructed MR images were matched with histologic sections at corresponding locations.
Forty-four samples were available for subsequent evaluation of agreement or disagreement between plaque components and image contrast differences. Of samples, 52.3% (n = 23) showed no image contrast heterogeneity; this group comprised solely no lesions or early lesions. Of samples, 25.0% (n = 11, mostly advanced lesions) showed good correlation between the spatial organization of MR imaging heterogeneities and plaque components. Areas of foamy macrophages were generally seen as proton attenuation-, T2-, and T2*- hypointense areas, while areas of increased collagen content showed more ambiguous signal intensities. Five samples showed image-contrast heterogeneity without corresponding plaque components on histology; 5 other samples showed contrast heterogeneity based on intima-media artifacts.
MR imaging at 7T has the image contrast capable of identifying both focal intracranial vessel wall thickening and distinguishing areas of different signal intensities spatially corresponding to plaque components within more advanced atherosclerotic plaques.
多项研究尝试利用磁共振成像序列对颅内动脉粥样硬化斑块进行特征描述。然而，这些序列与组织学的专门验证尚未开展。本研究以组织学为标准，评估了具有不同图像对比权重的超高分辨率7T磁共振成像序列对斑块成分成像的能力。
对5个Willis环标本在7T下进行成像，采用面内分辨率为0.11×0.11mm的质子衰减加权、T1加权、T2加权和T2*加权序列（层面分辨率为0.11 - 1mm）。对磁共振成像上13个基准标记位置（每个标本）的组织样本进行组织学处理和动脉粥样硬化斑块分类。重建的磁共振图像与相应位置的组织学切片进行匹配。
44个样本可用于后续评估斑块成分与图像对比差异之间的一致性或不一致性。其中，52.3%（n = 23）的样本未显示图像对比异质性；该组仅包括无病变或早期病变。25.0%（n = 11，大多为晚期病变）的样本显示磁共振成像异质性的空间组织与斑块成分之间具有良好的相关性。泡沫巨噬细胞区域通常表现为质子衰减加权、T2加权和T2*加权低信号区，而胶原含量增加的区域信号强度表现得更为模糊。5个样本显示图像对比异质性，但组织学上无相应的斑块成分；另外5个样本显示基于内膜 - 中膜伪影的对比异质性。
7T磁共振成像具有图像对比能力，能够识别局灶性颅内血管壁增厚，并在空间上区分更晚期动脉粥样硬化斑块内与斑块成分相对应的不同信号强度区域。
