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Updated: Jun 5, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
Improving the Detection of Myelin Integrity in Multiple Sclerosis Using Selective Inversion Recovery for MRI With
Ahmad A Toubasi1, Dhairya A Lakhani1,2, Gary Cutter3
1Neuroimaging Unit, Neuroimmunology Division, Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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 T1-weighted (T1-w) turbo spin echo, T2-w fluid-attenuated inversion recovery (FLAIR), DTI, and SIR-qMT sequences.
Assessment:
T2-lesions were identified as hyperintense on T2-w-FLAIR, and chronic black holes (cBHs) by simultaneous T2-w-FLAIR hyperintensity and T1-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 T2-lesions and cBHs were compared to their matched p/dNAWM and NWM in HCs. Comparisons were also made between T2-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 T2-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. T2-lesions (P = 0.051). PSR had significantly higher accuracy in differentiating T2-lesions from p/dNAWM and NWM, with a larger ES when comparing T2-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.
Insights
Selective inversion recovery quantitative magnetization transfer (SIR-qMT)-derived macromolecular to free water pool size ratio (PSR) is more accurate than diffusion tensor imaging (DTI)-derived radial diffusivity (RD) for detecting tissue injury in multiple sclerosis (MS). PSR offers superior accuracy and effect size for assessing myelin integrity.
Area of Science:
- Neuroimaging
- Biomarkers
- Multiple Sclerosis Research
Background:
- Selective inversion recovery quantitative magnetization transfer (SIR-qMT) and diffusion tensor imaging (DTI) offer potential metrics for assessing myelin integrity in multiple sclerosis (MS).
- Macromolecular to free water pool size ratio (PSR) from SIR-qMT and radial diffusivity (RD) from DTI are key metrics under investigation.
- Establishing the accuracy of PSR and RD in identifying MS-related tissue injury is crucial for clinical translation.
Purpose of the Study:
- To compare the diagnostic accuracy and Cohen's effect size (ES) of PSR and RD.
- To evaluate the ability of PSR and RD to detect and quantify tissue injury in early MS patients.
- To determine which metric, PSR or RD, is superior for assessing MS pathology.
Main Methods:
- A cross-sectional prospective study involving 43 newly diagnosed MS patients and 18 healthy controls (HCs).
- 3-Tesla MRI scans were acquired using T1-weighted, T2-weighted fluid-attenuated inversion recovery (FLAIR), DTI, and SIR-qMT sequences.
- Regions of interest (ROIs) were defined in T2-lesions, chronic black holes (cBHs), normal-appearing white matter (NAWM) proximal and distant to lesions, and normal white matter (NWM) in HCs. Receiver operating characteristic curves and paired t tests were used for analysis.
Main Results:
- PSR values significantly differed across all comparisons between MS lesions/NAWM and NWM in HCs.
- RD values also differed significantly, except when comparing cBHs to T2-lesions (P = 0.051).
- PSR demonstrated significantly higher accuracy and a larger effect size than RD in differentiating T2-lesions and cBHs from various white matter regions.
Conclusions:
- Macromolecular to free water pool size ratio (PSR) derived from SIR-qMT exhibits superior accuracy and effect size compared to radial diffusivity (RD) from DTI.
- PSR is a more effective metric for detecting and quantifying tissue injury in multiple sclerosis (MS).
- These findings support the clinical utility of PSR as a sensitive biomarker for MS-related white matter damage.
