Reliability and Value of 3D Sequential QUantitative T1-T2-T2 MAppings (SQUMA) MR Multi-Parametric Imaging in Characterizing Carotid Artery Atherosclerosis

Background T-1, T-2, and T-2* mappings are seldom performed in a single examination, and their values in evaluating symptomatic atherosclerosis are lacking. Purpose To perform three-dimensional (3D) quantitative T-1, T-2, and T-2* mappings (SQUMA) multi-parametric imaging for carotid vessel wall and evaluate its reliability and value in assessing carotid atherosclerosis. Study Type Prospective. Subjects Eight healthy subjects and 20 patients with symptomatic carotid atherosclerosis. Field Strength/Sequence 3 T, SQUMA imaging T-1-, T-2-, and T-2*-mapping, multi-contrast vessel wall imaging including T-1- and T-2-weighted, time-of-flight, and SNAP sequences. Assessment SQUMA was acquired in all subjects and multi-contrast images were acquired in healthy subjects. T-1, T-2, and T-2* values and lumen area (LA), wall area (WA), mean wall thickness (MeanWT), and normalized wall index (NWI) of carotid arteries were measured. SQUMA and multi-contrast measurements were compared in healthy subjects and differences in SQUMA measurements between healthy subjects and patients were assessed. The discriminative value of SQUMA measurements for symptomatic vessel was determined. Statistical Tests Paired t or Wilcoxon signed-rank test, independent t or Mann-Whitney U test, area under the receiver operating characteristic curve (AUC), intraclass correlation coefficients, and Bland-Altman plots. Statistically significant level, P < 0.05. Results There were no significant differences in LA (P = 0.340), WA (P = 0.317), MeanWT (P = 0.088), and NWI (P = 0.091) of carotid arteries between SQUMA and multi-contrast vessel wall images. The values of T-2 (50.9 +/- 2.9 msec vs. 44.5 +/- 4.2 msec), T-2* (28.2 +/- 4.3 msec vs. 24.7 +/- 2.6 msec), WA (23.7 +/- 4.6 mm(2) vs. 36.2 +/- 7.7 mm(2)), MeanWT (0.99 +/- 0.05 mm vs. 1.50 +/- 0.28 mm), and NWI (40.7 +/- 3.0% vs. 53.8 +/- 5.4%) of carotid arteries in healthy subjects were significantly different from those in atherosclerotic patients. The combination of quantitative T-1, T-2, and T-2* values and MeanWT showed greatest AUC (0.81; 95% CI: 0.65-0.92) in discriminating symptomatic vessels. Data Conclusion Carotid MR 3D quantitative multi-parametric imaging of SQUMA enables acquisition of T-1, T-2, and T-2* maps, reliably measuring carotid morphology and discriminating carotid symptomatic atherosclerosis. Level of Evidence 2 Technical Efficacy Stage 2

Automated summary

This study evaluated carotid atherosclerosis using three-dimensional quantitative imaging (SQUMA) and found that the combination of T-1, T-2, and T-2* values and mean wall thickness showed the best performance in discriminating symptomatic vessels.