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Updated: Dec 7, 2025
Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
Published on: February 19, 2021
In Vivo Proton Exchange Rate (kex ) MRI for the Characterization of Multiple Sclerosis Lesions in Patients
Haiqi Ye1, Mehran Shaghaghi2, Qianlan Chen1
1Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Background:
Currently available radiological methods do not completely capture the diversity of multiple sclerosis (MS) lesion subtypes. This lack of information hampers the understanding of disease progression and potential treatment stratification. For example, inflammation persists in some lesions after gadolinium (Gd) enhancement resolves. Novel metabolic and molecular imaging methods may improve the current assessments of MS pathophysiology.
Purpose:
To compare the in vivo proton exchange rate (kex ) MRI with Gd-enhanced MRI for characterizing MS lesions.
Study Type:
Retrospective.
Subjects:
Sixteen consecutively diagnosed relapsing-remitting multiple sclerosis (RRMS) patients.
Field Strength/Sequence:
3.0T MRI with T2 -weighted imaging, postcontrast T1 -weighted imaging, and single-slice chemical exchange saturation transfer imaging.
Assessment:
MS lesions in white matter were assessed for Gd enhancement and kex elevation compared to normal-appearing white matter (NAWM).
Statistical Tests:
Student's t-test was used for analyzing the difference of kex values between lesions and NAWM, with statistical significance set at 0.05.
Results:
Of all 153 MS lesions, 78 (51%) lesions were Gd-enhancing and 75 (49%) were Gd-negative. Without exception, all 78 Gd-enhancing lesions showed significantly elevated kex values compared to NAWM (924 ± 130 s-1 vs. 735 ± 61 s-1 , P < 0.05). Of 75 Gd-negative lesions, 18 lesions (24%) showed no kex elevation (762 ± 29 s-1 vs. 755 ± 28 s-1 , P = 0.47) and 57 (76%) showed significant kex elevation (950 ± 124 s-1 vs. 759 ± 48 s-1 , P < 0.05) compared to NAWM. MS lesions with kex elevation appeared nodular (118, 87.4%), ring-like (15, 11.1%), or irregular-shaped (2, 1.5%).
Data Conclusion:
For Gd-enhancing lesions, kex MRI is highly consistent with Gd-enhanced images by showing 100% of elevated kex . For all Gd-negative lesions, the discrepancy on kex MRI may further differentiate active slowly expanding lesions or chronic inactive lesions, supporting kex as an imaging biomarker for tissue oxidative stress and inflammation. Level of Evidence 2 Technical Efficacy Stage 3 J. MAGN. RESON. IMAGING 2021;53:408-415.
Insights
Proton exchange rate (kex) MRI shows elevated inflammation in multiple sclerosis (MS) lesions, even those not enhancing with gadolinium (Gd). This novel imaging method may help differentiate active from inactive MS lesions.
Area of Science:
- Radiology
- Neuroimaging
- Biomarkers
Background:
- Current radiological methods for multiple sclerosis (MS) do not fully capture lesion diversity, hindering understanding of disease progression and treatment stratification.
- Inflammation can persist in MS lesions even after gadolinium (Gd) enhancement resolves, indicating limitations of existing imaging techniques.
- Novel metabolic and molecular imaging approaches are needed to improve the assessment of MS pathophysiology.
Purpose of the Study:
- To compare in vivo proton exchange rate (kex) MRI with Gd-enhanced MRI for characterizing MS lesions.
- To evaluate the utility of kex MRI in identifying active inflammation in MS lesions.
Main Methods:
- Retrospective study of 16 relapsing-remitting MS patients.
- Utilized 3.0T MRI with T2-weighted imaging, postcontrast T1-weighted imaging, and single-slice chemical exchange saturation transfer (CEST) imaging.
- Assessed Gd enhancement and kex elevation in MS lesions compared to normal-appearing white matter (NAWM) using Student's t-test.
Main Results:
- Of 153 MS lesions, 78 were Gd-enhancing and 75 were Gd-negative.
- All 78 Gd-enhancing lesions showed significantly elevated kex compared to NAWM (P < 0.05).
- Of 75 Gd-negative lesions, 76% (57 lesions) demonstrated significant kex elevation compared to NAWM (P < 0.05), suggesting ongoing inflammation.
Conclusions:
- kex MRI is highly consistent with Gd-enhanced imaging for detecting active inflammation in MS lesions.
- kex MRI can identify inflammation in Gd-negative lesions, potentially differentiating active from inactive lesions.
- kex MRI shows promise as an imaging biomarker for tissue oxidative stress and inflammation in MS.
