Semiautomated Segmentation and Volume Measurements of Cervical Carotid High-Signal Plaques Using 3D Turbo Spin-Echo T1-Weighted Black-Blood Vessel Wall Imaging: A Preliminary Study.

Unstable carotid plaques are visualized as high-signal plaques (HSPs) on 3D turbo spin-echo T1-weighted black-blood vessel wall imaging (3D TSE T1-BB VWI). The purpose of this study was to compare manual segmentation and semiautomated segmentation for the quantification of carotid HSPs using 3D TSE T1-BB VWI. Twenty cervical carotid plaque lesions in 19 patients with a plaque contrast ratio of > 1.3 compared to adjacent muscle were studied. Using the mean voxel value for the adjacent muscle multiplied by 1.3 as a threshold value, the semiautomated software exclusively segmented and measured the HSP volume. Manual and semiautomated HSP volumes were well correlated (r = 0.965). Regarding reproducibility, the inter-rater ICC was 0.959 (bias: 24.63, 95% limit of agreement: −96.07, 146.35) for the manual method and 0.998 (bias: 15.2, 95% limit of agreement: −17.83, 48.23) for the semiautomated method, indicating improved reproducibility by the semiautomated method compared to the manual method. The time required for semiautomated segmentation was significantly shorter than that of manual segmentation times (81.7 ± 7.8 s versus 189.5 ± 49.6 s; p < 0.01). The results obtained in this study demonstrate that the semiautomated segmentation method allows for reliable assessment of the HSP volume in patients with carotid plaque lesions, with reduced time and effort for the analysis.

Cervical carotid plaque evaluation using 3D T1-weighted black-blood magnetic resonance imaging: Comparison of turbo field-echo and turbo spin-echo sequences.

PURPOSE: To compare the capability of three-dimensional (3D) T1-weighted turbo field-echo (TFE) black-blood (BB) magnetic resonance imaging (MRI) and turbo-spin echo (TSE) BB MRI for discerning carotid plaques and the difference of signal intensities of the plaques from that of adjacent muscle in patients with cervical carotid stenosis. METHODS: Cervical carotid stenosis was evaluated by 3.0-T MR in 43 patients (38 men and 5 women; age, 36-83 years; mean age, 70 years) during 8 months. The carotid BB MRI comprised 3D T1-weighted TSE BB (T1-TSEBB) and 3D T1-weighted TFE BB (T1-TFEBB) sequences. The delineation of the carotid plaque border was evaluated in comparison with digital subtraction angiography (DSA). The border between the plaque and vessel lumen was rated visually (4-point analysis) and quantitatively (contrast-to-noise ratio). The signal-intensity ratio (SIR) of the plaque to the adjacent muscle was also measured. Data of 3D T1-TSEBB and 3D T1-TFEBB were compared statistically using the Wilcoxon signed-rank test. RESULTS: Visual and quantitative analyses revealed that the border between the plaque and vessel lumen was better delineated on 3D T1-TSEBB MRI than on 3D T1-TFEBB MRI (p<0.01, respectively). SIR of the plaque-to-adjacent muscle was higher on 3D T1- TFEBB MRI than on 3D T1-TSEBB MRI (p<0.05). High signal plaques with a SIR of >1.5 were underestimated on 3D T1-TSEBB MRI. CONCLUSIONS: 3D T1-TSEBB MRI was superior to 3D T1-TFEBB MRI for delineating carotid plaques; however, high signal plaques were underestimated on 3D T1-TSEBB MRI.