AJDRAJNR - American Journal of Neuroradiology

Published ahead of print on February 22, 2008
doi: 10.3174/ajnr.A1015
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Characterization of Carotid Atherosclerosis and Detection of Soft Plaque with Use of Black-Blood MR Imaging

K. Yoshidaa, O. Narumia, M. China, K. Inoueb, T. Tabuchic, K. Odac, M. Nagayamac, N. Egawad, M. Hojoa, Y. Gotoa, Y. Watanabec and S. Yamagataa

a Department of Neurosurgery, Kurashiki Central Hospital, Okayama, Japan
b Department of Cardiology, Kurashiki Central Hospital, Okayama, Japan
c Department of Radiology, Kurashiki Central Hospital, Okayama, Japan
d Department of Neurology, Kurashiki Central Hospital, Okayama, Japan


Figure 1
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  		Fig 1. The rSI of plaque components on T1- and T2-weighted images. With use of specimens with matching MR images and excised plaque sections, the rSI of plaque components was calculated in relationship to the sternocleidomastoid muscle on T1-weighted images and the submandibular gland on T2-weighted images. On T1-weighted images, rSI significantly differed among most components, but not between FC and calcification, fibrosis and myxomatous tissues, fibrosis and LC without IPH, and myxomatous tissue and LC without IPH. On T2-weighted images, rSI significantly differed between FC and the other components except for LC without IPH, and between calcification and the other components. Bars indicate SD. FC indicates fibrous cap; Calc., calcification; MT, myxomatous tissue; LC-IPH(+), LC with intraplaque hemorrhage; and LC-IPH(-), LC without intraplaque hemorrhage.


Figure 2
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  		Fig 2. A–E, An example of MR images and histopathologic features of atherosclerotic plaque consisting of LC with intraplaque hemorrhage. First, a long-axis image of the carotid artery including a stenotic lesion was obtained (A), and based on this image, 3 T1-weighted and 3 T2-weighted short-axis images of the artery were obtained for plaque characterization. B–C, Axial T1- (B) and T2- (C) weighted images corresponding to the intermediate section in the long-axis image (A). Inset, a magnification of the atherosclerotic carotid plaque. A manual operator-defined ROI was drawn on a workstation to refer to the histologic features (a, LC-IPH(+); b, FC), and the rSI at the corresponding location on the matched MR image was measured. The rSI for LC-IPH(+) on T1- and T2-weighted images were 1.89 and 0.85, respectively. The rSI for FC on T1- and T2-weighted images were 0.71 and 0.53 in this case. SCM indicates sternocleidomastoid muscle; SMG, submandibular gland; asterisk, lumen. D, Gross sections of carotid endarterectomy specimen at approximately 2-mm intervals. A section corresponding to axial MR images (B–C) is marked with an arrow. E, Masson trichrome–stained cross section matched to axial MR images (B–C) showed an abundant LC-IPH(+) and FC (a and b, manual operator-defined ROIs for LC-IPH(+) (a) and FC (b).


Figure 3
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  		Fig 3. A–C, An example of MR images and histopathologic features of carotid plaque with mixed components. A and B, Short-axis T1- and T2-weighted images. Inset, a magnification of the atherosclerotic carotid plaque. With manual operator-defined ROIs for calcification (a) and fibrosis (b) as major components, the rSIs of calcification and fibrosis on T1-weighted images were 0.61 and 1.05, respectively. In the same way, the rSIs of calcification and fibrosis on T2-weighted image was 0.3 and 1.3, respectively. Asterisks indicate the lumen. C, Masson trichrome stained cross section matched to axial MR images (A,B) demonstrate so-called hard plaque composed of abundant collagen fibers (b) and calcification (a). Small intraplaque hemorrhage was also confirmed in this section.


Figure 4
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  		Fig 4. A–D, An example of MR images and histopathologic features of plaque mainly consisting of myxomatous tissue. A and B, Short-axis T1- and T2-weighted images. Inset, a magnification of the atherosclerotic carotid plaque. With manual operator-defined ROI for myxomatous tissue, the rSIs on T1- and T2-weighted imaging were 1.18 and 2.0, respectively. Asterisks indicate the lumen. C and D, The low- and high-power histologic cross section (Masson trichrome stain; original magnification, 3.87 and 25) matched to axial MR images (A and B). Manual operator-defined ROI for rSI calculation is shown on low-power cross section (C). Myxomatous tissue contains pleomorphic smooth muscle cells and a large amount of extracellular matrix mainly composed of proteoglycan. Remarkable hyperintensity on T2-weighted image (B) is characteristic of myxomatous plaque, which might reflect that the extracellular matrix is associated with abundant water molecules.





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