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Updated: Jun 2, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
High-Field-Blinded Assessment of Portable Ultra-Low-Field Brain MRI for Multiple Sclerosis
Serhat V Okar1, Govind Nair2, Karan D Kawatra3
1Translational Neuroradiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
Background And Purpose:
MRI is crucial for multiple sclerosis (MS), but the relative value of portable ultra-low field MRI (pULF-MRI), a technology that holds promise for extending access to MRI, is unknown. We assessed white matter lesion (WML) detection on pULF-MRI compared to high-field MRI (HF-MRI), focusing on blinded assessments, assessor self-training, and multiplanar acquisitions.
Methods:
Fifty-five adults with MS underwent pULF-MRI following their HF-MRI. Two neuroradiologists independently assessed pULF-MRI images in an evaluation process, including initial assessment blinded to HF-MRI, self-training with reference to HF-MRI and evaluation of 20 cases with additional T2-fluid-attenuated inversion recovery in an additional plane. A third rater conducted cross-referenced analysis with HF-MRI data to determine true-positive lesions, false-positive areas, and case-level sensitivity and positive predictive value.
Results:
The mean age of participants was 50 years (standard deviation: 11; 74% women). Initially, Rater 2 marked more false-positive areas than Rater 1 (p = 0.003). After self-training, both raters embraced a conservative approach, with Rater 2 marking fewer false-positive areas (p = 0.01). Both raters maintained 100% case-level sensitivity and positive predictive value for detecting at least one WML, particularly in periventricular areas. Multiplanar acquisitions reduced both false-positive areas and true-positive lesions. True-positive lesions and false-positive areas had similar contrast-to-noise ratios in the juxtacortical region (p = 0.73) but not in periventricular, deep parenchymal regions (p = 0.004, p = 0.01).
Conclusion:
With adequate training, radiological interpretation of pULF-MRI has high sensitivity and positive predictive value for MS lesions but should be approached conservatively. These results suggest utility for patient triage, potentially reducing diagnostic delay, and screening high-risk individuals.
Insights
Portable ultra-low field MRI (pULF-MRI) shows high sensitivity and positive predictive value for detecting multiple sclerosis (MS) white matter lesions after training. This technology may help triage patients and reduce diagnostic delays.
Area of Science:
- Neuroimaging
- Radiology
- Medical Technology
Background:
- Magnetic Resonance Imaging (MRI) is essential for multiple sclerosis (MS) diagnosis and monitoring.
- Portable ultra-low field MRI (pULF-MRI) offers potential for increased MRI accessibility.
- The diagnostic value of pULF-MRI for MS white matter lesions (WMLs) compared to high-field MRI (HF-MRI) requires evaluation.
Purpose of the Study:
- To assess the efficacy of pULF-MRI in detecting WMLs in patients with MS.
- To compare WML detection on pULF-MRI against HF-MRI.
- To evaluate the impact of blinded assessments, assessor self-training, and multiplanar acquisitions on pULF-MRI performance.
Main Methods:
- Fifty-five adults with MS underwent both pULF-MRI and HF-MRI.
- Two neuroradiologists independently assessed pULF-MRI images, including blinded assessments and post-training evaluations.
- A third rater performed cross-referenced analysis with HF-MRI to determine lesion accuracy, calculating case-level sensitivity and positive predictive value.
Main Results:
- Following self-training, both raters demonstrated improved accuracy, with reduced false-positive areas.
- Both raters achieved 100% case-level sensitivity and positive predictive value for detecting at least one WML.
- Multiplanar acquisitions decreased false-positive areas and true-positive lesions; contrast-to-noise ratios varied by lesion location.
Conclusions:
- Radiological interpretation of pULF-MRI demonstrates high sensitivity and positive predictive value for MS lesions, contingent on adequate training.
- A conservative approach to pULF-MRI interpretation is recommended.
- pULF-MRI shows promise for patient triage, potentially shortening diagnostic timelines and screening high-risk individuals.
