Related Experiment Video
Updated: Apr 27, 2026
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
Filtered-phase imaging versus susceptibility-weighted imaging for paramagnetic rim lesion detection in multiple
Chris Hollen1, Carolina Garcia1, Christopher C Hemond2
1Department of Neurology, Oregon Health & Science University, Portland, OR, USA; Portland VA Medical Center, Portland, OR, USA.
Background:
Paramagnetic rim lesions (PRLs) detected on susceptibility-sensitive magnetic resonance imaging (MRI) represent chronic active lesions and correlate with disease progression in multiple sclerosis (MS). However, optimal detection methods remain unclear.
Objective:
To compare PRL detection using filtered-phase imaging versus susceptibility-weighted imaging (SWI) and assess inter-rater reliability among clinical neuroimmunologists.
Methods:
We retrospectively analyzed 3T MRI from 44 relapsing-remitting MS patients. Four neurologists with neuroimmunology training received 30-minute training sessions and evaluated PRLs on both filtered-phase and SWI sequences. Consensus adjudication resolved discordant ratings and served as the reference standard for calculating diagnostic accuracy.
Results:
PRLs were identified in 21/44 patients (48%). Relative to consensus as the reference standard, SWI demonstrated higher sensitivity than filtered-phase imaging (66.0% vs. 60.4%), while filtered phase showed superior positive predictive value (0.903 vs. 0.714). Both sequences achieved very high specificity (>97%). Inter-rater reliability was good for SWI (Intraclass Correlation Coefficient [ICC] = 0.85) and moderate for filtered phase (ICC = 0.71) for per-subject PRL counts. Vascular complexity was the most common cause of false-positive identification (65% of cases).
Conclusions:
Both techniques reliably detect PRLs with substantial inter-rater agreement. Filtered-phase imaging offers superior positive predictive value, while SWI provides better sensitivity and inter-rater reliability. Further development of a standardized training program for assessment of PRL and studies directly comparing susceptibility-sensitive sequences on different vendor platforms are warranted.
Insights
Susceptibility-weighted imaging (SWI) and filtered-phase imaging both detect paramagnetic rim lesions (PRLs) in multiple sclerosis (MS). SWI offers higher sensitivity and reliability, while filtered-phase imaging provides better positive predictive value for these chronic active lesions.
Area of Science:
- Neuroimaging
- Radiology
- Neurology
Background:
- Paramagnetic rim lesions (PRLs) on MRI indicate active, chronic lesions in multiple sclerosis (MS).
- PRLs correlate with disease progression in MS.
- Optimal MRI techniques for detecting PRLs are not yet established.
Purpose of the Study:
- To compare the effectiveness of filtered-phase imaging versus susceptibility-weighted imaging (SWI) for detecting PRLs.
- To evaluate the inter-rater reliability of PRL detection among neuroimmunologists.
Main Methods:
- Retrospective analysis of 3T MRI scans from 44 relapsing-remitting MS patients.
- Four trained neurologists assessed PRLs using both filtered-phase and SWI sequences.
- Consensus adjudication was used as the reference standard for accuracy assessment.
Main Results:
- PRLs were detected in 48% of patients.
- SWI showed higher sensitivity (66.0%) compared to filtered-phase imaging (60.4%).
- Filtered-phase imaging had a superior positive predictive value (0.903 vs. 0.714), with both sequences exceeding 97% specificity.
- SWI demonstrated better inter-rater reliability (ICC=0.85) than filtered phase (ICC=0.71).
Conclusions:
- Both filtered-phase imaging and SWI reliably detect PRLs with good inter-rater agreement.
- Filtered-phase imaging offers higher positive predictive value, while SWI provides better sensitivity and reliability.
- Standardized training and multi-vendor platform comparisons are needed for PRL assessment.
