7T quantitative magnetization transfer (qMT) of cortical gray matter in multiple sclerosis correlates with cognitive impairment

McKeithan, Lydia; Lyttle, Bailey D.; Box, Bailey A.; O’Grady, Kristin P.; Dortch, Richard D.; Conrad, Benjamin; Thompson, Lindsey; Rogers, Baxter P.; Newhouse, Paul; Pawate, Siddharama; Bagnato, Francesca; Smith, Seth A.

doi:10.1016/j.neuroimage.2019.116190

Cited by 18 publications

(22 citation statements)

References 47 publications

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“…The study of NAGM abnormalities in vivo, made possible by advanced MRI techniques including magnetization transfer imaging (MTI) [ 61 ], quantitative relaxometry [ 62 ], quantitative susceptibility mapping (QSM) [ 63 ] and diffusion MRI [ 64 ], has provided valuable insights into MS pathophysiology and has proved worthwhile in terms of clinical correlations, even if it is not always clear to what extent these correlations are driven by GM atrophy [ 60 ]. In particular, globally reduced MT ratio in the NAGM, considered as an index of demyelination, has been related to cognitive impairment in MS patients [ 65 , 66 ]. In accordance with this finding, T1 relaxometry studies demonstrated an association between cognitive impairment and higher mean values and skewness of GM T1-relaxation time, both reflecting demyelination, mainly in the thalamus and fronto-temporal cortices [ 67 , 68 , 69 ].…”

Section: Structural Correlates Of Cognitive Impairmentmentioning

confidence: 99%

Neuroimaging Correlates of Cognitive Dysfunction in Adults with Multiple Sclerosis

et al. 2021

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Cognitive impairment is a frequent and meaningful symptom in multiple sclerosis (MS), caused by the accrual of brain structural damage only partially counteracted by effective functional reorganization. As both these aspects can be successfully investigated through the application of advanced neuroimaging, here, we offer an up-to-date overview of the latest findings on structural, functional and metabolic correlates of cognitive impairment in adults with MS, focusing on the mechanisms sustaining damage accrual and on the identification of useful imaging markers of cognitive decline.

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Section: Structural Correlates Of Cognitive Impairmentmentioning

confidence: 99%

Neuroimaging Correlates of Cognitive Dysfunction in Adults with Multiple Sclerosis

et al. 2021

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“…In certain applications, this assumption may be violated. For example, recent work has reported that the MT exchange rate may correlate with cognitive impairment in multiple sclerosis 43 . As shown in Equation (), the proposed approach can be used to quantify MT parameters other than MPF.…”

Section: Discussionmentioning

confidence: 99%

Macromolecular proton fraction mapping based on spin‐lock magnetic resonance imaging

Hou

Wong

Jiang

et al. 2020

Magnetic Resonance in Med

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Purpose In MRI, the macromolecular proton fraction (MPF) is a key parameter of magnetization transfer (MT). It represents the relative amount of immobile protons associated with semi‐solid macromolecules involved in MT with free water protons. We aim to quantify MPF based on spin‐lock MRI and explore its advantages over the existing MPF‐mapping methods. Methods In the proposed method, termed MPF quantification based on spin‐lock (MPF‐SL), off‐resonance spin‐lock is used to sensitively measure the MT effect. MPF‐SL is designed to measure a relaxation rate (Rmpfsl) that is specific to the MT effect by removing the R1ρ relaxation due to the mobile water and chemical exchange pools. A theory is derived to quantify MPF from the measured Rmpfsl. No prior knowledge of tissue relaxation parameters, including T1 or T2, is needed to quantify MPF using MPF‐SL. The proposed approach is validated with Bloch‐McConnell simulations, phantom, and in vivo liver studies at 3.0T. Results Both Bloch‐McConnell simulations and phantom experiments show that MPF‐SL is insensitive to variations of the mobile water pool and the chemical exchange pool. MPF‐SL is specific to the MT effect and can measure MPF reliably. In vivo liver studies show that MPF‐SL can be used to detect collagen deposition in patients with liver fibrosis. Conclusion A novel MPF imaging method based on spin‐lock MRI is proposed. The confounding factors are removed, and the measurement is specific to the MT effect. It holds promise for MPF‐sensitive diagnostic imaging in clinical settings.

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“…The median TE was 11.70 ms (k=73, range: 1.23 ms [41][42][43][44]68,79 to 90 ms 38,[52][53][54]64 ). Some studies did not, however, report TR (k=12) 30,31,39,50,56,58,71,72,87,91,108,110 or TE (k=13). 31,33,39,58,69,71,72,87,91,102,108,110,112 The excitation flip angle ranged from 3° for a 3D FLASH (fast low-angle shot) acquisition 67 to 90° for 3D selective inversion recovery (SIR)-turbo SE & 3D SIR-EPI (echo planar imaging), 50 T1-weighted 2D SE 100 and PD-weighted MT sequences, 88 with a median of 15° (k=55).…”

Section: Image Contrast: Tr Te and Excitation Flip Anglementioning

confidence: 99%

“…Two studies used onresonance pulse MTI but did not report further details 55,86 and fourteen studies did not report the offset frequency. 31,34,37,56,68,72,79,87,94,99,100,106,108,110…”

Section: Radiofrequency Pulse Frequencymentioning

confidence: 99%

“…30,33,35,47,50,51,56-58,67,69,72,80,84,91,112 30,33,35,47,50,51,56-58,67,69,72,74,80,84,91,112 . qMT parameters included the R1free (k=7) 30,33,35,47,50,56,69 or T1free (k=5) 51,58,67,80,91 including under saturation (T1sat, k=2), 57,58 T2free (k=4) 33,35,47,69 and T2bound (k=5), 33,35,47,51,69 kf (k=8) 30,33,56,67,69,72,80,91 including under saturation (ksat, k=2), 57,58 the equilibrium magnetisation of the "bound" pool and the non-ideal inversion of the "free" pool signal (M0f and Sf, respectively, k=2), 30,56 f (k=3), 35,47,51 and F (k=2). 30,33,47,50,56,69,72,112…”

Section: Metrics Usedmentioning

confidence: 99%

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Quantitative magnetisation transfer imaging in relapsing-remitting multiple sclerosis: a systematic review and meta-analysis

York

Thrippleton

Meijboom

et al. 2021

Preprint

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Myelin-sensitive MRI such as magnetisation transfer imaging has been widely used in the clinical context of multiple sclerosis. The influence of methodology and differences in disease subtype on imaging findings is, however, not well established. Here, we aim to review systematically the use of quantitative magnetisation transfer imaging in the brain in relapsing-remitting multiple sclerosis. We examine how methodological differences, disease effects and their interaction influence magnetisation transfer imaging measures. Articles published before 06/01/2021 were retrieved from online databases (PubMed, EMBASE and Web of Science) with search terms including "magnetisation transfer" and "brain" for systematic review. Only studies which used human in vivo quantitative magnetisation transfer imaging in adults with relapsing-remitting multiple sclerosis (with or without healthy controls) were included. Data including sample size, magnetic field strength, MRI acquisition protocol parameters, treatments and clinical findings were extracted. Where possible, effect sizes were calculated for meta-analyses to determine magnetisation transfer (1) differences between patients and healthy controls; (2) longitudinal change; and, (3) relationships with clinical disability in relapsing-remitting multiple sclerosis. Eighty-six studies met the inclusion/exclusion criteria. MRI acquisition parameters varied widely, and were also underreported. The majority of studies examined MTR (magnetisation transfer ratio) in white matter, but magnetisation transfer metrics, brain regions and results were heterogeneous. Analysis demonstrated a risk of bias due to selective reporting and small sample sizes. A random-effects meta-analysis revealed MTR was 1.1 percent units [95% CI -1.47pu to -0.73pu] lower in relapsing-remitting multiple sclerosis than healthy controls (z-value: -6.04, p<0.001, n=23). Linear mixed-model analysis did not show a significant longitudinal change in MTR across all brain regions (β=-0.14 [-0.9 to 0.61], t-value=-0.38, p=0.71, n=13) or normal-appearing white matter alone (β=-0.082 [-0.13 to -0.29], t-value=0.78, p=0.44, n=7). There was a significant negative association between MTR and clinical disability, as assessed by the Expanded Disability Status Scale (r=-0.30 [95% CI -0.48 to -0.08]; z-value=-2.91, p=0.01, n=8). Evidence suggests that magnetisation transfer imaging is sensitive to pathological changes in relapsing-remitting multiple sclerosis, although the effect of relapsing-remitting multiple sclerosis on magnetisation transfer metrics in different brain tissue types was small in comparison to the inter-study variability. Recommended improvements include: the use of techniques such as MTsat (magnetisation transfer saturation) or ihMTR (inhomogeneous MTR) which provide more robust and specific microstructural measures within clinically feasible acquisition times; detailed methodological reporting standards; and larger, demographically diverse cohorts for comparison, including healthy controls.

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7T quantitative magnetization transfer (qMT) of cortical gray matter in multiple sclerosis correlates with cognitive impairment

Cited by 18 publications

References 47 publications

Neuroimaging Correlates of Cognitive Dysfunction in Adults with Multiple Sclerosis

Neuroimaging Correlates of Cognitive Dysfunction in Adults with Multiple Sclerosis

Macromolecular proton fraction mapping based on spin‐lock magnetic resonance imaging

Quantitative magnetisation transfer imaging in relapsing-remitting multiple sclerosis: a systematic review and meta-analysis

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