CTA for Screening of Complicated Atherosclerotic Carotid Plaque—American Heart Association Type VI Lesions as Defined by MRI

M. Trelles; K.M. Eberhardt; M. Buchholz; A. Schindler; A. Bayer-Karpinska; M. Dichgans; M.F. Reiser; K. Nikolaou; T. Saam

doi:10.3174/ajnr.A3607

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Fig 1.
General plaque characteristics by MR imaging–derived American Heart Association lesion type. Thickness is given in centimeters, density in Hounsfield units, stenosis in percentage (%) ± confidence interval.
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Fig 2.
Receiver operating characteristic curves for the performance of the maximum wall thickness, maximum soft plaque thickness, maximum hard plaque thickness, mean attenuation NASCET percentage stenosis values, and presence of ulceration in screening for complicated AHA-LT6 plaques (area under the curve, 0.810 ± 0.084, 0.897 ± 0.063, 0.433 ± 0.123, 0.384 ± 0.155, 0.756 ± 0.106, and 0.602 ± 0.139, respectively).
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Fig 3.
CTA image through a complicated AHA-LT6 plaque in the right carotid artery at the carotid bifurcation shows a soft plaque with a mean attenuation of 16 HU (range, −7 to 46) and a thickness of the soft plaque component of 6 mm. TOF, T1, T2, and T1 postgadolinium images at the same level show a hyperintense plaque on all 4 weightings, which suggests the presence of type II IPH.
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Fig 4.
TOF, T1, T2, and T1 postgadolinium images of a complicated AHA-LT6 plaque in the left internal carotid artery. The plaque is hyperintense on TOF and T1WI and hypointense on T2WI, which suggests the presence of type I IPH. The CT image at the identical location shows a high attenuation soft plaque with a mean attenuation of 51 HU (range, 29–144) and a thickness of the soft plaque component of 8 mm.

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Table 1:

Patient characteristics

	Study Population (n = 51)
Demographic
Age, y	71.3 ± 0.9
Male sex	74%
Body mass index	26.0 ± 0.3
CT imaging
Stenosis, % (NASCET)	26.7% ± 5.6%
Cardiovascular risk factors
Smoker	25.5% (13)
Ex-smoker	41.2% (21)
Hypertension	76.5% (39)
Hypercholesterolemia	45.1% (23)
Diabetes	23.5% (12)
Coronary heart disease	13.7% (7)
Family history of cardiovascular events	31.4% (16)

Note:—Values are mean ± CI unless otherwise shown.

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Table 2:

General plaque characteristics by MRI-derived AHA lesion type

MRI-AHA Lesion Type	Maximum Wall Thickness	Maximum Soft Plaque Thickness	Maximum Hard Plaque Thickness	Minimum Density	Maximum Density	Mean Density	NASCET Percentage Stenosis
I-II	2.2 ± 0.6	1.8 ± 0.6	1.4 ± 0.8	38 ± NA^a	197 ± NA^a	82 ± NA^a	0.0% ± NA^a
III	3.7 ± 0.5	1.8 ± 0.8	3.0 ± 0.5	41 ± 18	224 ± 68	114 ± 29	15.1% ± 12.5%
IV-V	4.0 ± 0.3	2.9 ± 0.5	2.4 ± 0.5	14 ± 10	134 ± 21	59 ± 12	21.1% ± 8.0%
VI	5.3 ± 0.4	4.7 ± 0.5	2.5 ± 0.5	18 ± 9	143 ± 18	60 ± 12	46.3% ± 10.6%
VII	4.4 ± 0.7	1.1 ± 0.5	3.9 ± 0.5	31 ± 8	215 ± 33	91 ± 11	33.1% ± 14.0%
Total	4.2 ± 0.3	2.8 ± 0.4	2.7 ± 0.3	20 ± 6	152 ± 17	67 ± 9	26.7% ± 5.6%

Note:—Thickness is given in millimeters; density of the soft plaque component in Hounsfield units (HU) ±CI. AHA indicates American Heart Association.
↵a Only 1 HU measurement was obtained for AHA lesion type I/II, therefore no CIs are reported.

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Table 3:

General plaque characteristics of noncomplicated versus complicated AHA-LT6 by MRI

	AHA-LT6	Others	P Value
Maximum wall thickness	5.3 ± 0.4	3.9 ± 0.3	(<.001)
Maximum soft plaque thickness	4.7 ± 0.5	2.2 ± 0.3	(<.001)
Maximum hard plaque thickness	2.5 ± 0.5	2.7 ± 0.3	(.24)
Minimum density	18 ± 9	21 ± 9	(.36)
Maximum density	143 ± 18	162 ± 24	(.16)
Mean density	60 ± 12	72 ± 12	(.12)
NASCET percentage stenosis	46.3% ± 10.6%	20.5% ± 6.0%	(<.001)
Presence of ulcer	15.8% ± 19.5%	34.8% ± 7.8%	(.02)

Note:—Thickness is given in millimeters; density in Hounsfield Units ±CI.

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Table 4:

Interreader and intermeasurement intraclass correlation coefficients for maximum wall, calcified plaque, and soft plaque thickness

	Interreader Intraclass Correlation Coefficient	First Axial Reading versus Orthogonal Intraclass Correlation Coefficient	Second Axial Reading versus Orthogonal Intraclass Correlation Coefficient
Maximum wall thickness	0.94 (0.89–0.97)	0.86 (0.75–0.92)	0.93 (0.87–0.96)
Maximum calcified plaque thickness	0.69 (0.48–0.83)	0.80 (0.64–0.89)	0.69 (0.47–0.82)
Maximum soft plaque thickness	0.95 (0.91–0.98)	0.93 (0.87–0.96)	0.97 (0.94–0.98)