Magnetization Transfer Ratio in Gray Matter

Khaleeli, Zhaleh; Altmann, Daniel R.; Cercignani, Mara; Ciccarelli, Olga; Miller, David H.; Thompson, Alan J.

doi:10.1001/archneur.65.11.1454

Cited by 57 publications

(11 citation statements)

References 34 publications

(41 reference statements)

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“…23 Wallerian degeneration, both anterograde and retrograde, secondary to proximal and/or distal axonal damage has also been implicated as a mechanism contributing to lower MTR in the gray matter. 24,64 The strong afferent and efferent connectivity of the caudate makes this another credible neurobiological explanation for our finding. The relative contributions of these mechanisms to the MTR may vary across disease states.…”

Section: Discussionsupporting

confidence: 53%

Subcortical biophysical abnormalities in patients with mood disorders

et al. 2013

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Cortical–subcortical circuits have been implicated in the pathophysiology of mood disorders. Structural and biochemical abnormalities have been identified in patients diagnosed with mood disorders using magnetic resonance imaging-related approaches. In this study, we used magnetization transfer (MT), an innovative magnetic resonance approach, to study biophysical changes in both gray and white matter regions in cortical–subcortical circuits implicated in emotional regulation and behavior. Our study samples comprised 28 patients clinically diagnosed with major depressive disorder (MDD) and 31 non-depressed subjects of comparable age and gender. MT ratio (MTR), representing the biophysical integrity of macromolecular proteins within key components of cortical–subcortical circuits—the caudate, thalamic, striatal, orbitofrontal, anterior cingulate and dorsolateral regions—was the primary outcome measure. In our study, the MTR in the head of the right caudate nucleus was significantly lower in the MDD group when compared with the comparison group. MTR values showed an inverse relationship with age in both groups, with more widespread relationships observed in the MDD group. These data indicate that focal biophysical abnormalities in the caudate nucleus may be central to the pathophysiology of depression and critical to the cortical–subcortical abnormalities that underlie mood disorders. Depression may also accentuate age-related changes in the biophysical properties of cortical and subcortical regions. These observations have broad implications for the neuronal circuitry underlying mood disorders across the lifespan.

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Section: Discussionsupporting

confidence: 53%

Subcortical biophysical abnormalities in patients with mood disorders

et al. 2013

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“…Recent observations suggest that GM is involved in an inflammatory demyelination process in early MS (Inglese et al, 2011; Khaleeli et al, 2008; Lucchinetti et al, 2011). However, no evidence was observed to confirm the change in tight junctions within the BBB in the GM of patients with MS (van Horssen et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Quantification of blood-to-brain transfer rate in multiple sclerosis

Taheri

Rosenberg

Ford

2013

Multiple Sclerosis and Related Disorders

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Blood–brain barrier (BBB) disruption visualized in lesions by MRI is a major biomarker of disease activity in multiple sclerosis (MS). However, in MS, destruction occurs to a variable extent in lesions as well as in gray matter (GM) and in the normal appearing white matter (NAWM). A method to quantify the BBB disruption in lesions as well as in non-lesion areas would be useful for assessment of MS progression and treatments. The objective of this study was to quantify the BBB transfer rate (Ki) in WM lesions, in the NAWM, and in the full-brain of MS patients. Thirteen MS patients with active lesions and 10 healthy controls with age and gender matching were recruited for full-brain and WM Ki studies. Dynamic contrast-enhanced MRI (DCEMRI) scans were conducted using T1 mapping with partial inversion recovery (TAPIR), a fast T1 mapping technique, following administration of a quarter-dose of the contrast agent Gadolinium-DTPA (Gd-DTPA). The Patlak modeling technique was used to derive a voxel-based map of Ki. In all patients contrast-enhanced lesions, quantified by Ki maps, were observed. Compared with controls, patients with MS exhibited an increase in mean Ki of the full-brain (P-value<0.05) but no significant difference in mean Ki of NAWM. The identified increase in full-brain Ki of MS patients suggests a global vascular involvement associated with MS disease. The lack of observed significant decrease in Ki in NAWM suggests lower involvement of WM vasculature than full-brain vasculature in MS. Ki maps constructed from time series data acquired by DCEMRI provide additional information about BBB that could be used for evaluation of vascular involvement in MS and monitoring treatment effectiveness.

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“…Although GM atrophy and lesion load are known to be good predictors of clinical disability and clinical outcome (Charil et al, 2007; Khaleeli et al, 2008), the causal relationship between these two surrogate markers is still uncertain (Chard and Miller, 2009; Miller et al, 2002). Mapping the topography of cortical lesions and atrophy across time could potentially provide new insights into the interaction of these two markers (Mainero et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

In vivo evidence of disseminated subpial T2* signal changes in multiple sclerosis at 7 T: A surface-based analysis

et al. 2011

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Cortical subpial demyelination is frequent in multiple sclerosis (MS) and is closely associated with disease progression and poor neurological outcome. Although cortical lesions have been difficult to detect using conventional MRI, preliminary data using T2*-weighted imaging at ultra-high field 7T MRI showed improved sensitivity for detecting and categorizing different histological types of cortical MS lesions. In this study we combined high-resolution 7T MRI with a surface-based analysis technique to quantify and map subpial T2*-weighted signal changes in seventeen patients with MS. We applied a robust method to register 7T data with the reconstructed cortical surface of each individual and used a general linear model to assess in vivo an increase in subpial T2*-weighted signal in patients versus age-matched controls, and to investigate the spatial distribution of cortical subpial changes across the cortical ribbon. We also assessed the relationship between subpial T2* signal changes at 7T, Expanded Disability Status Scale (EDSS) score and white matter lesion load (WMLL). Patients with MS showed significant T2*-weighted signal increase in the frontal lobes (parsopercularis, precentral gyrus, middle and superior frontal gyrus, orbitofrontal cortex), anterior cingulate, temporal (superior, middle and inferior temporal gyri), and parietal cortices (superior and inferior parietal cortex, precuneus), but also in occipital regions of the left hemisphere. We found significant correlations between subpial T2*-weighted signal and EDSS score in the precentral gyrus (R=0.56, P=0.02) and between T2*-weighted signal and WMLL in the lateral orbitofrontal, superior parietal, cuneus, precentral and superior frontal regions. Our data support the presence of disseminated subpial increases in T2* signal in subjects with MS, which may reflect the diffuse subpial pathology described in neuropathology.

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Magnetization Transfer Ratio in Gray Matter

Cited by 57 publications

References 34 publications

Subcortical biophysical abnormalities in patients with mood disorders

Subcortical biophysical abnormalities in patients with mood disorders

Quantification of blood-to-brain transfer rate in multiple sclerosis

In vivo evidence of disseminated subpial T2* signal changes in multiple sclerosis at 7 T: A surface-based analysis

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