Related Experiment Video
Updated: Jul 20, 2026
Rat Model of Widespread Cerebral Cortical Demyelination Induced by an Intracerebral Injection of Pro-Inflammatory Cytokines
Published on: September 21, 2021
Evidence for a white matter lesion size threshold to support the diagnosis of relapsing remitting multiple sclerosis
S Grahl1, V Pongratz1, P Schmidt1
1Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81541, Munich, Germany; TUM Neuroimaging Center, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81541, Munich, Germany.
Background:
The number of white matter lesions (WML) in brain MRI is the most established paraclinical tool to support the diagnosis of multiple sclerosis (MS) and to monitor its course. Diagnostic criteria have stipulated a minimum detectable diameter of 3 mm per WML, although this threshold is not evidence-based. We aimed to provide a rationale for a WML size threshold for three-dimensional MRI sequences at 3 T by comparing patients with relapsing-remitting MS (RRMS) to control subjects (CS).
Methods:
We analyzed MR images from two cohorts, obtained at scanners from two different vendors, each comprising patients with RRMS and CS. Both cohorts were examined with FLAIR and T1w sequences. In total, 232 patients with RRMS (Expanded Disability Status Scale: mean = 1.6 ± 1.2; age: mean = 36 ± 10) as well as 116 age- and sex-matched CS were studied. We calculated odds ratios across WML volumes. The WML size threshold, which discriminated best between patients and CS, was estimated with receiver operating characteristic curve analysis.
Results:
In both cohorts, odds ratios increased continuously with increasing WML volumes, and discriminative power was highest at a WML size threshold corresponding to a diameter of about 3 mm.
Conclusion:
The stipulated WML size threshold of 3 mm in diameter for the diagnostic criteria of MS seems a reasonable choice for three-dimensional MRI sequences at 3 T.
Insights
The 3 mm white matter lesion diameter threshold is a reasonable choice for diagnosing multiple sclerosis (MS) using 3-Tesla MRI. This size effectively differentiates MS patients from healthy controls in brain imaging studies.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- White matter lesions (WML) on brain MRI are crucial for diagnosing and monitoring multiple sclerosis (MS).
- Current diagnostic criteria use a 3 mm WML diameter threshold, but this lacks strong evidence.
- Research is needed to validate WML size thresholds for advanced MRI techniques.
Purpose of the Study:
- To establish an evidence-based rationale for a WML size threshold in 3D MRI sequences at 3 Tesla.
- To compare WML characteristics between relapsing-remitting MS patients and control subjects.
- To determine the optimal WML size threshold for discriminating MS from healthy controls.
Main Methods:
- Analysis of brain MRI scans (FLAIR, T1w) from two independent cohorts (232 RRMS patients, 116 controls).
- Utilized 3D MRI sequences at 3 Tesla across different scanner vendors.
- Employed receiver operating characteristic (ROC) curve analysis to estimate the best discriminating WML size threshold.
Main Results:
- Odds ratios for MS increased continuously with WML volume in both cohorts.
- The highest discriminative power between MS patients and controls was observed at a WML diameter threshold of approximately 3 mm.
- This finding held true across different MRI vendors and cohorts.
Conclusions:
- The established 3 mm WML diameter threshold appears to be a reasonable and effective criterion for MS diagnosis using 3D MRI at 3 Tesla.
- This study provides a scientific basis for the current diagnostic guideline.
- The findings support the continued use of the 3 mm threshold in clinical practice for MS detection.
