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Updated: Oct 28, 2025
Positron Emission Tomography Imaging for In Vivo Measuring of Myelin Content in the Lysolecithin Rat Model of Multiple Sclerosis
Published on: February 28, 2021
Multicomponent T2 relaxometry reveals early myelin white matter changes induced by proton radiation treatment
Pietro Bontempi1, Daniele Scartoni1, Dante Amelio1
1Proton Therapy Unit, Hospital of Trento, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy.
Purpose:
To investigate MRI myelin water imaging (MWI) by multicomponent T2 relaxometry as a quantitative imaging biomarker for brain radiation-induced changes and to compare it with DTI.
Methods:
Sixteen patients underwent fractionated proton therapy (PT) receiving dose to the healthy tissue because of direct or indirect (base skull tumors) irradiation. MWI was performed by a multi-echo sequence with 32 equally spaced echoes (10-320 ms). Decay data were processed to identify 3 T2 compartments: myelin water (Mw) below 40 ms, intra-extracellular water (IEw) between 40 and 250 ms, and free water (CSFw) above 250 ms. Both MWI and DTI scans were acquired pre (pre)-treatment and immediately at the end (end) of PT. After image registration, voxel-wise difference maps, obtained by subtracting MWI and DTI pre from those acquired at the end of PT, were compared with the corresponding biological equivalent dose (BED).
Results:
Mw difference showed a positive correlation and IEw difference showed a negative correlation with BED considering end-pre changes (P < .01). The changes in CSFw were not significantly correlated with the delivered BED. The changes in DTI data, considering end-pre acquisitions, showed a positive correlation between fractional anisotropy and the delivered BED.
Conclusion:
MWI might detect early white matter radiation-induced alterations, providing additional information to DTI, which might improve the understanding of the pathogenesis of the radiation damage.
Insights
Myelin water imaging (MWI) can detect early white matter changes after radiation therapy. This quantitative MRI technique provides insights beyond diffusion tensor imaging (DTI), aiding in understanding radiation damage.
Area of Science:
- Radiology
- Neuroimaging
- Oncology
Background:
- Radiation therapy can induce changes in brain white matter.
- Quantitative imaging biomarkers are needed to assess these radiation-induced alterations.
- Diffusion tensor imaging (DTI) is commonly used but may have limitations.
Purpose of the Study:
- To evaluate MRI myelin water imaging (MWI) using multicomponent T2 relaxometry as a quantitative biomarker for radiation-induced brain changes.
- To compare the efficacy of MWI with DTI in detecting these changes.
Main Methods:
- Sixteen patients undergoing fractionated proton therapy were studied.
- MWI and DTI scans were acquired before and after treatment.
- Changes in MWI and DTI parameters were correlated with the biological equivalent dose (BED).
Main Results:
- Myelin water (Mw) changes positively correlated with BED, while intra-extracellular water (IEw) changes negatively correlated.
- Free water (CSFw) changes did not significantly correlate with BED.
- DTI's fractional anisotropy showed a positive correlation with BED.
Conclusions:
- MWI shows potential for detecting early white matter alterations following radiation therapy.
- MWI may offer complementary information to DTI for understanding radiation-induced brain damage.
- This could lead to improved monitoring and management of patients.
