Atherosclerotic Plaques: Classification and Characterization with T2-weighted High-Spatial-Resolution MR Imaging—An in Vitro Study1
Jean-Michel Serfaty, MD,
Linda Chaabane, MS,
André Tabib, MD,
Jean-Michel Chevallier, MD,
André Briguet, PhD and
Phillippe C. Douek, MD, PhD
1 From the Laboratoire de Résonance Magnétique Nuclèaire Unité Mixte de Recherche, Villeurbanne, France (J.M.S., L.C., A.B.); Department of Radiology (J.M.S., P.C.D., J.M.C.) and Centre de Recherche et d’Applications en Traitement d l’Image et du Signal (J.M.S., P.C.D.), Hôpital Cardiovasculaire et Pneumologique L. Pradel, Bron, France; Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Md (J.M.S.); and Department of Vascular Surgery, Hôpital Edouart Herriot, Lyon, France (A.T.). From the 1999 RSNA scientific assembly. Received December 6, 1999; revision requested January 18, 2000; final revision received August 15; accepted September 12. Supported by a grant from La Fondation pour la Recherche Médicale, Paris, France. Address correspondence to J.M.S., Department of Diagnostic and Therapeutic Imaging, Hôpital Cardio-Vasculaire, B.P. Lyon Montchat, 69394 Lyon Cedex 03, France (e-mail: jserfaty@mri.jhu.edu).
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Figure 1. Schematic depicts the correlation between MR imaging sections and histologic slices. During the MR imaging experiment, seven transverse 1.5-mm-thick MR imaging sections were obtained at the center of the specimen. During histologic examination, the specimen was cut seven times into eight equal tissue rings as follows: a = one cut in the center of the specimen, b = one cut in the center of each of the two halves, and c = one cut in the center of each of the four quarters. Two tissue rings were analyzed microscopically.
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Figure 2. Schematic depicts measurement of the ratio (in percentage [p]) between lipid core thickness (a) and total intimal thickness (b): p = (a/b) x 100. In this example, p = (a/b) x 100 = 30%. L = lumen.
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Figure 3a. Carotid artery. In a and b, a = adventitia, L = lumen, m = media, p = periadventitial fat. (a) Transverse T2-weighted SE MR image (2,000/50) shows the lumen with high signal intensity, the adventitia with low signal intensity, the media with intermediate signal intensity, and the perivascular fat with low signal intensity (type 0 plaque, MR imaging classification). (b) Corresponding transverse photomicrograph shows concentric type II intimal thickening (i, arrowheads)(type I-II plaque, AHA classification). (Hematoxylin-eosin and safranin stain; original magnification, x4.)
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Figure 3b. Carotid artery. In a and b, a = adventitia, L = lumen, m = media, p = periadventitial fat. (a) Transverse T2-weighted SE MR image (2,000/50) shows the lumen with high signal intensity, the adventitia with low signal intensity, the media with intermediate signal intensity, and the perivascular fat with low signal intensity (type 0 plaque, MR imaging classification). (b) Corresponding transverse photomicrograph shows concentric type II intimal thickening (i, arrowheads)(type I-II plaque, AHA classification). (Hematoxylin-eosin and safranin stain; original magnification, x4.)
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Figure 4a. Carotid endarterectomy. In a and b, F = fibrous cap. (a) Transverse T2-weighted SE MR image (2,000/50) shows a large area of low signal intensity (arrow) surrounded by a tissue cap with heterogeneous signal intensity (type IV-Va plaque, MR imaging classification). (b) Corresponding transverse photomicrograph confirms the presence of a large granular lipidic core (arrow) surrounded by a thick, dense fibrous cap unequally infiltrated with lipids (stained black) (type IV-Va plaque, AHA classification). (Black Sudan stain; original magnification, x4.)
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Figure 4b. Carotid endarterectomy. In a and b, F = fibrous cap. (a) Transverse T2-weighted SE MR image (2,000/50) shows a large area of low signal intensity (arrow) surrounded by a tissue cap with heterogeneous signal intensity (type IV-Va plaque, MR imaging classification). (b) Corresponding transverse photomicrograph confirms the presence of a large granular lipidic core (arrow) surrounded by a thick, dense fibrous cap unequally infiltrated with lipids (stained black) (type IV-Va plaque, AHA classification). (Black Sudan stain; original magnification, x4.)
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Figure 5a. Iliac artery. (a) Transverse T2-weighted SE MR image (2,000/50) shows an upper (1) fibrocalcic plaque (type Vb, MR imaging classification) and a lower (2) plaque (type IV-Va, MR imaging classification). (b) Corresponding transverse photomicrograph confirms the fibrocalcic plaque (1) (type Vb, AHA classification) but also a recent thrombosis due to dissection of the media (M) (2). The thrombus (T) mimics a large lipidic core, whereas the media mimics a thin fibrotic cap. c = calcification. (Hematoxylin-eosin and safranin stain; original magnification, x4.)
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Figure 5b. Iliac artery. (a) Transverse T2-weighted SE MR image (2,000/50) shows an upper (1) fibrocalcic plaque (type Vb, MR imaging classification) and a lower (2) plaque (type IV-Va, MR imaging classification). (b) Corresponding transverse photomicrograph confirms the fibrocalcic plaque (1) (type Vb, AHA classification) but also a recent thrombosis due to dissection of the media (M) (2). The thrombus (T) mimics a large lipidic core, whereas the media mimics a thin fibrotic cap. c = calcification. (Hematoxylin-eosin and safranin stain; original magnification, x4.)
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Figure 6a. Carotid endarterectomy. In a, b, and d, L = lumen and O = region of the plaque magnified in d. (a) Transverse T2-weighted SE MR image (2,000/50) shows homogeneous high signal intensity (type Vc, MR imaging classification). (b, c) Corresponding transverse photomicrographs at different magnifications show an infiltration of dead foam cells (d) surrounded by thin collagenous fibers (type IV-Va, AHA classification). (Hematoxylin-eosin and safranin stain; original magnification: b, x4; c, x20.) (d) Corresponding transverse photomicrograph shows no lipidic infiltration, suggesting a hydrophilic necrosis. (Sudan III stain; original magnification, x10.)
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Figure 6b. Carotid endarterectomy. In a, b, and d, L = lumen and O = region of the plaque magnified in d. (a) Transverse T2-weighted SE MR image (2,000/50) shows homogeneous high signal intensity (type Vc, MR imaging classification). (b, c) Corresponding transverse photomicrographs at different magnifications show an infiltration of dead foam cells (d) surrounded by thin collagenous fibers (type IV-Va, AHA classification). (Hematoxylin-eosin and safranin stain; original magnification: b, x4; c, x20.) (d) Corresponding transverse photomicrograph shows no lipidic infiltration, suggesting a hydrophilic necrosis. (Sudan III stain; original magnification, x10.)
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Figure 6c. Carotid endarterectomy. In a, b, and d, L = lumen and O = region of the plaque magnified in d. (a) Transverse T2-weighted SE MR image (2,000/50) shows homogeneous high signal intensity (type Vc, MR imaging classification). (b, c) Corresponding transverse photomicrographs at different magnifications show an infiltration of dead foam cells (d) surrounded by thin collagenous fibers (type IV-Va, AHA classification). (Hematoxylin-eosin and safranin stain; original magnification: b, x4; c, x20.) (d) Corresponding transverse photomicrograph shows no lipidic infiltration, suggesting a hydrophilic necrosis. (Sudan III stain; original magnification, x10.)
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Figure 6d. Carotid endarterectomy. In a, b, and d, L = lumen and O = region of the plaque magnified in d. (a) Transverse T2-weighted SE MR image (2,000/50) shows homogeneous high signal intensity (type Vc, MR imaging classification). (b, c) Corresponding transverse photomicrographs at different magnifications show an infiltration of dead foam cells (d) surrounded by thin collagenous fibers (type IV-Va, AHA classification). (Hematoxylin-eosin and safranin stain; original magnification: b, x4; c, x20.) (d) Corresponding transverse photomicrograph shows no lipidic infiltration, suggesting a hydrophilic necrosis. (Sudan III stain; original magnification, x10.)
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Figure 7. Quantification of lipidic core thickness at MR imaging and histologic examination. Graph shows that the lipid core was overestimated ( 30%) with MR imaging for 43% of the arteries. The graph shows the linear regression line and the linear regression equation and its regression R2 coefficient value.
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Figure 8a. Carotid endarterectomy. In a-c, arrows = lipidic core. (a) Transverse T2-weighted SE MR image (2,000/50) shows a low-signal-intensity area (arrow) that occupies a maximum of 80% of plaque thickness (MR imaging classification, type IV-Va). (b) Corresponding transverse photomicrograph shows a lipidic core stabilized within by collagenous fibers (type IV-Va, AHA classification; percentage of plaque diameter, 80%). (Hematoxylin-eosin and safranin stain; original magnification, x4.) (c) Corresponding transverse photomicrograph shows a small necrotic core (n) and an important extracellular lipidic deposit around collagenous fibers. (Black Sudan stain; original magnification, x4.)
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Figure 8b. Carotid endarterectomy. In a-c, arrows = lipidic core. (a) Transverse T2-weighted SE MR image (2,000/50) shows a low-signal-intensity area (arrow) that occupies a maximum of 80% of plaque thickness (MR imaging classification, type IV-Va). (b) Corresponding transverse photomicrograph shows a lipidic core stabilized within by collagenous fibers (type IV-Va, AHA classification; percentage of plaque diameter, 80%). (Hematoxylin-eosin and safranin stain; original magnification, x4.) (c) Corresponding transverse photomicrograph shows a small necrotic core (n) and an important extracellular lipidic deposit around collagenous fibers. (Black Sudan stain; original magnification, x4.)
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Figure 8c. Carotid endarterectomy. In a-c, arrows = lipidic core. (a) Transverse T2-weighted SE MR image (2,000/50) shows a low-signal-intensity area (arrow) that occupies a maximum of 80% of plaque thickness (MR imaging classification, type IV-Va). (b) Corresponding transverse photomicrograph shows a lipidic core stabilized within by collagenous fibers (type IV-Va, AHA classification; percentage of plaque diameter, 80%). (Hematoxylin-eosin and safranin stain; original magnification, x4.) (c) Corresponding transverse photomicrograph shows a small necrotic core (n) and an important extracellular lipidic deposit around collagenous fibers. (Black Sudan stain; original magnification, x4.)
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Copyright © 2001 by the Radiological Society of North America.
