Assessment of quantitative methods for enhancement measurement on vessel wall magnetic resonance imaging evaluation of intracranial atherosclerosis

Abstract

Purpose: Quantitative measures of vessel wall magnetic resonance imaging (vwMRI) for the evaluation of intracranial atherosclerotic disease (ICAD) offers standardization not available with previously used qualitative approaches that may be difficult to replicate.

Methods: vwMRI studies performed to evaluate ICAD that had caused a stroke were analyzed. Two blinded reviewers qualitatively rated culprit lesions for the presence of enhancement on T1 delay alternating with nutation for tailored excitation (DANTE) SPACE images. At least 3 months later, quantitative analysis was performed of the same images, comparing lesion enhancement to reference structures. Cohen's kappa and intraclass correlation coefficients were calculated to assess agreement. Ratios of enhancement of lesions to references were compared to qualitative ratings.

Results: Studies from 54 patients met inclusion criteria. A mean of 49 (90.7%) lesions were qualitatively rated as enhancing, with good inter-rater agreement (κ = 0.783). Among reference structure candidates, low infundibulum demonstrated the highest inter-rater agreement on pre- and post-contrast imaging. The ratio of percentage increase in plaque signal following contrast to the same measure in low infundibulum demonstrated the highest agreement with qualitative assessment, with highest agreement seen with a ratio of 0.8 set as a threshold (κ = 0.675).

Conclusion: Quantitative metrics can yield objective data to better standardize techniques and acceptance of vwMRI evaluation of ICAD. The low infundibulum had the highest inter-rater agreement on both pre- and post-contrast images and is best suited as a normally enhancing reference structure. Such quantitative techniques should be implemented in future research of vwMRI for the evaluation of ICAD.

Keywords: Imaging; Intracranial atherosclerosis; MRI; Quantitative analysis; Vessel wall.

Conflict of interest statement

Conflict of interest—The authors declare that they have no conflict of interest.

Figures

Figure 1.

Sequence diagram for 3D DANTE T1W SPACE sequence, which consists of 150 trains of DANTE module followed by 3D T1W SPACE readouts.

Figure 2.

Representative images of structures analyzed and intensities recorded before and after administration of contrast: (A, B) symptomatic left MCA ICAD plaque, (C, D) normal right MCA wall segment, (E, F) low infundibulum, (G, H) mid infundibulum, (I, J) choroid plexus, (K, L) cavernous sinus, (M, N) temporalis muscle.

Figure 3.

Graphical representation of Cohen’s Kappa values for ratios of signal measurements of plaque over various reference structures.