Improving the Detection of Myelin Integrity in Multiple Sclerosis Using Selective Inversion Recovery for MRI With Quantitative Magnetization Transfer.

BACKGROUND

Selective inversion recovery quantitative magnetization transfer (SIR-qMT)-derived macromolecular to free water pool size ratio (PSR) and diffusion tensor imaging (DTI)-derived radial diffusivity (RD) are potential metrics for assessing myelin integrity in multiple sclerosis (MS). However, establishing their accuracy in identifying tissue injury is essential for clinical translation.

PURPOSE

To compare the accuracy and Cohen's effect size (ES) of PSR and RD in detecting and quantifying tissue injury in early MS.

STUDY TYPE

Cross-sectional prospective study.

SUBJECTS

Fourty-three subjects with newly diagnosed MS (mean age 38 ± 11 years, 70% females) and 18 age- and sex-matched healthy controls (HCs; age 38 ± 12 years, 62.5% females).

FIELD STRENGTH/SEQUENCE: 3-T MRI using T-weighted (T-w) turbo spin echo, T-w fluid-attenuated inversion recovery (FLAIR), DTI, and SIR-qMT sequences.

ASSESSMENT

T-lesions were identified as hyperintense on T-w-FLAIR, and chronic black holes (cBHs) by simultaneous T-w-FLAIR hyperintensity and T-w hypointensity. Regions of interest (ROIs) in normal-appearing white matter (NAWM) were classified as proximal (p) or distant (d) to lesions, while normal white matter (NWM) was identified in HCs. PSR and RD values of T-lesions and cBHs were compared to their matched p/dNAWM and NWM in HCs. Comparisons were also made between T-lesions and cBHs.

STATISTICAL TESTS

Receiver operating characteristic curves evaluated metric accuracy, and paired t tests compared ES values of PSR and RD, with significance set at P < 0.050.

RESULTS

We identified 823 T-lesions, 392 cBHs, 426 p-, and 213 d-NAWM ROIs in patients, and 162 NWM ROIs in HCs. PSR differed significantly in all comparisons, while RD was differed in all except cBHs vs. T-lesions (P = 0.051). PSR had significantly higher accuracy in differentiating T-lesions from p/dNAWM and NWM, with a larger ES when comparing T-lesions to p/dNAWM and NWM and cBHs to pNAWM and NWM.

DATA CONCLUSION

PSR offers superior accuracy and ES over RD in detecting tissue injury in MS.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 2.