Quantitative Evaluation of Carotid Artery Stenosis by Multi-VENC 4D Flow MRI: Incorporating Turbulent Kinetic Energy for Clinical Validity.

BACKGROUND

Cervical internal carotid artery stenosis (ICS) is a recognized risk factor for ischemic stroke, yet morphological severity alone may not fully reflect hemodynamic alterations. Turbulent kinetic energy (TKE), derived from multi-velocity-encoding (multi-VENC) four-dimensional (4D) flow MRI, may provide a robust marker for ICS assessment, though its utility in carotid arteries remains underexplored.

PURPOSE

To investigate the reproducibility of TKE measurement and to assess correlations with MR angiography (MRA)-derived stenosis, black blood T1-weighted imaging (T1BB)-derived plaque scale, and ultrasound parameters.

STUDY TYPE

Prospective.

POPULATION

Twenty-three patients (6 [26%] female; median age: 72 years, IQR: 60-80) with suspected ICS based on cerebrovascular symptoms or screening carotid ultrasound.

FIELD STRENGTH/SEQUENCE: 3-T, multi-VENC (33-100-300 cm/s) 4D flow MRI of the carotid arteries at 1.0 mm isotropic resolution, using k-space-time principal component analysis (k-t PCA) acceleration, time of flight-MRA (3D gradient-echo), and T1BB (turbo spin echo).

ASSESSMENT

Two neuroradiologists measured TKE once per case for interobserver evaluation. TKE was measured in a volume from just proximal to the bifurcation and slightly distal to the ICA stenosis. TKEbeat was defined as the total TKE integrated over the cardiac cycle. Stenosis and plaque features were assessed by MRA and T1BB, respectively. Carotid ultrasound parameters included peak systolic velocity, resistance index, intima-media thickness (IMT), and plaque characteristics.

STATISTICAL TESTS

Intraclass correlation coefficient (ICC) and Bland-Altman analyses were used for interobserver agreements. Associations between TKEbeat and conventional parameters were evaluated using Spearman's rank correlation. TKEbeat was compared between subgroups based on stenosis, plaque grade, and vascular risk factors using Mann-Whitney U-tests. Significance threshold: p < 0.05.

RESULTS

The ICC was 0.922 for TKEbeat. TKE correlated with stenosis (r = 0.309), plaque scale (r = 0.392), and IMT (r = 0.543). TKEbeat was higher in the stenosis group.

DATA CONCLUSION

Multi-VENC 4D flow MRI enables reproducible TKE measurement correlated with carotid stenosis and plaque features.

EVIDENCE LEVEL

Level 1. TECHNICAL EFFICACY: Stage 1.