Fast Whole-Brain Three-dimensional Macromolecular Proton Fraction Mapping in Multiple Sclerosis

Abstract

).q RSNA, 2014 Purpose:To evaluate the clinical utility of fast whole-brain macromolecular proton fraction (MPF) mapping in multiple sclerosis (MS) and compare MPF with established quantitative magnetic resonance (MR) imaging measures of tissue damage including magnetization transfer (MT) ratio and relaxation rate (R1). Materials and Methods:In this institutional review board-approved and HIPAAcompliant study, 14 healthy control participants, 18 relapsing-remitting MS (RRMS) patients, and 12 secondary progressive MS (SPMS) patients provided written informed consent and underwent 3-T MR imaging. Threedimensional MPF maps were reconstructed from MTweighted images and R1 maps by the single-point method.Mean MPF, R1, and MT ratio in normal-appearing white matter (WM), gray matter (GM), and lesions were compared between subject groups by using analysis of variance. Results:RRMS patients had lower WM and GM MPF than controls, with percentage decreases of 6.5% (P , .005) and 5.4% (P , .05). MPF in SPMS was reduced relative to RRMS in WM, GM, and lesions by 6.4% (P , .005), 13.4% (P , .005), and 11.7% (P , .05), respectively. EDSS and MSFC demonstrated strongest correlations with MPF in GM (r = 20.74 and 0.81; P , .001) followed by WM (r = 20.57 and 0.72; P , .01) and lesions (r = 20.42 and 0.50; P , .05). R1 and MT ratio in all tissues were significantly less correlated with clinical scores than GM MPF (P , .05). Conclusion:MPF mapping enables quantitative assessment of demyelination in normal-appearing brain tissues and shows primary clinical relevance of GM damage in MS. MPF outperforms MT ratio and R1 in detection of MS-related tissue changes.q RSNA, 2014

Quantitative Assessment of Normal Fetal Brain Myelination Using Fast Macromolecular Proton Fraction Mapping

“…The MPF is a biophysical parameter describing the amount of macromolecular protons in tissues involved in cross-relaxation with free water showed promising clinical results in adult brain studies 11,12 and has been histologically validated as an accurate quantitative tool for measuring demyelination. 10 The single-point technique 4 also allowed designing an ultrafast MPF mapping protocol for nonbrain applications.…”

Demyelination of subcortical nuclei in multiple sclerosis

“…Detailed characteristics of the study population can be found elsewhere [4]. Caudate nucleus, putamen, globus pallidus and substantia nigra were outlined on MPF maps.…”

“…At present it was obvious that gray matter damage which was poorly detectable using conventional MRI method occurred at the first stage of MS and correlated with clinical symptoms (both motor and cognitive) [2]- [4] Subcortical gray matter involvement in MS pathology was also observed [2], [5]but still need to be studied. In our research, basal ganglia demyelination in MS patients was evaluated using fast mapping of macromolecular proton fraction (MPF).…”

“…We present the results of secondary analysis of earlier published data [4] aimed to identify the effect of demyelination on MPF in subcortical gray matter structures in MS.…”

“…The method of fast MPF mapping was developed by Yarnykh [6] and based on the magnetization transfer effect. Of note, relaxation-based MRI methods [7]-[9] are highly sensitive to paramagnetic ions and hardly appropriate for the assessment of demyelination in structures with high iron content, such as basal ganglia In contrast, MPF mapping is a highly-accurate quantitative method insensitive to iron and, therefore, very suitable for studying demyelination in gray matter in MS.We present the results of secondary analysis of earlier published data [4] aimed to identify the effect of demyelination on MPF in subcortical gray matter structures in MS. …”