Contributions
Abstract: P1038
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - Imaging
Purpose: Myelin evolution of Multiple Sclerosis (MS) lesion can be monitored via MRI by using the traditional Magnetization Transfer Ration (MTR). However, inflammation, oedema and axonal loss together with myelination influence the MTR. Quantitative Magnetization Transfer (qMT) measure macromolecules content independently from T1 change due to oedema or inflammation. It can be measured via Chemical Exchange Saturation Transfer (CEST), and can be used to monitor accurately myelination changes inside and at the rim of the lesion taking into account the water content of the tissue. Recently susceptibility of the tissue, quantified by Quantitative Susceptibility Mapping (QSM) and indicating iron concentration, also showed evolution at the edge as well as inside the lesion during its formation. Here we present a longitudinal MS study aimed at tracking and quantifying lesion evolution with qMT together with QSM data.
Methods: With ethics approval, 4 patients with early Multiple Sclerosis were scanned 6 times with 6 weeks between scans (30 weeks total) using a 7T MRI. Imaging protocol includes Quantitative MT derived from CEST data as well as QSM derived from multi-echo T2star, standard FLAIR and PSIR images. FLAIR images were used to track MS lesions and create masks for ROI processing. Mean percentage MT pool sizes and susceptibility in an ROI drawn where white matter (WM) lesions appeared during the 30 weeks, were compared to regions of normal appearing WM close to the lesion site.
Results: We detected demyelination and remyelination as seen by changes of qMT in acute lesions as reported before. In addition we found a correlation of qMT with QSM inside the lesions both in crossectional analysis (r=-0.31, p=1e-9). The correlation in lesions was stronger than in the normal appearing tissue (r=-0.14, p=1e-9). However when the rim of acute lesions were studied we detected loss of qMT with initially associated loss of QSM. QSM increased signal appeared within 6 weeks. The differential appearance of QSM and qMT rings in acute lesions suggests degradation of myelin first and local accumulation of iron as a secondary effect.
Conclusion: Concomitant use of QSM and qMT concentration measurements appear to provide additional information about pathological changes in white matter lesions in MS and show promise for the study of early evolution of MS lesions.
Disclosure: Olivier Mougin: nothing to disclose
Amal Samaraweera: nothing to disclose
Nicolas Geades: nothing to disclose
Matthew Croning: nothing to disclose
Penny Gowland: nothing to disclose
Nikos Evangelou: nothing to disclose
Abstract: P1038
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - Imaging
Purpose: Myelin evolution of Multiple Sclerosis (MS) lesion can be monitored via MRI by using the traditional Magnetization Transfer Ration (MTR). However, inflammation, oedema and axonal loss together with myelination influence the MTR. Quantitative Magnetization Transfer (qMT) measure macromolecules content independently from T1 change due to oedema or inflammation. It can be measured via Chemical Exchange Saturation Transfer (CEST), and can be used to monitor accurately myelination changes inside and at the rim of the lesion taking into account the water content of the tissue. Recently susceptibility of the tissue, quantified by Quantitative Susceptibility Mapping (QSM) and indicating iron concentration, also showed evolution at the edge as well as inside the lesion during its formation. Here we present a longitudinal MS study aimed at tracking and quantifying lesion evolution with qMT together with QSM data.
Methods: With ethics approval, 4 patients with early Multiple Sclerosis were scanned 6 times with 6 weeks between scans (30 weeks total) using a 7T MRI. Imaging protocol includes Quantitative MT derived from CEST data as well as QSM derived from multi-echo T2star, standard FLAIR and PSIR images. FLAIR images were used to track MS lesions and create masks for ROI processing. Mean percentage MT pool sizes and susceptibility in an ROI drawn where white matter (WM) lesions appeared during the 30 weeks, were compared to regions of normal appearing WM close to the lesion site.
Results: We detected demyelination and remyelination as seen by changes of qMT in acute lesions as reported before. In addition we found a correlation of qMT with QSM inside the lesions both in crossectional analysis (r=-0.31, p=1e-9). The correlation in lesions was stronger than in the normal appearing tissue (r=-0.14, p=1e-9). However when the rim of acute lesions were studied we detected loss of qMT with initially associated loss of QSM. QSM increased signal appeared within 6 weeks. The differential appearance of QSM and qMT rings in acute lesions suggests degradation of myelin first and local accumulation of iron as a secondary effect.
Conclusion: Concomitant use of QSM and qMT concentration measurements appear to provide additional information about pathological changes in white matter lesions in MS and show promise for the study of early evolution of MS lesions.
Disclosure: Olivier Mougin: nothing to disclose
Amal Samaraweera: nothing to disclose
Nicolas Geades: nothing to disclose
Matthew Croning: nothing to disclose
Penny Gowland: nothing to disclose
Nikos Evangelou: nothing to disclose