Myelin water mapping by spatially regularized longitudinal relaxographic imaging at high magnetic fields

Labadie, Christian; Lee, Jing Huei; Rooney, William D.; Jarchow, Silvia; Aubert‐Frécon, M.; Springer, Charles S.; Möller, Harald E.

doi:10.1002/mrm.24670

Cited by 116 publications

(173 citation statements)

References 68 publications

Supporting

Mentioning

154

Contrasting

Order By: Relevance

“…(12) depends on R b 1 , which, thereby, also influences the estimation of R a 1 , the deviation might be related to an underestimation of the semisolid-pool relaxation rate constant, as proposed by Helms and Hagberg [39]. Moreover, brain tissue is known to have at least two separate free water T 2 components [48], and recent evidence supports the assumption that there are also separate free water T 1 components [49]. It is, thus, conceivable that the divergence in the estimates of R a 1 from the different fitting approaches might result from differently weighted averages of separate components contributing to the free water pool.…”

Section: Mt Experiments In Normal Human Brainmentioning

confidence: 92%

Matrix-algebra-based calculations of the time evolution of the binary spin-bath model for magnetization transfer

Müller¹,

Pampel²,

Möller³

2013

Journal of Magnetic Resonance

Self Cite

View full text Add to dashboard Cite

Section: Mt Experiments In Normal Human Brainmentioning

confidence: 92%

Matrix-algebra-based calculations of the time evolution of the binary spin-bath model for magnetization transfer

Müller¹,

Pampel²,

Möller³

2013

Journal of Magnetic Resonance

Self Cite

View full text Add to dashboard Cite

“…This is usually sufficient and the T1 relaxation can then be described by a single value. In real tissue, however, multi-exponential T1 behaviour has been detected (67), and it may be more accurate to model T1 using several exponents:…”

Section: T1 Relaxationmentioning

confidence: 99%

“…1.16 and 1.27), either on a continuous spectrum or using discrete distributions (67,70,71,85). These in vivo models have been created with two (70,71,86) or three (87) separate water environments.…”

Section: Myelin Water Fractionmentioning

confidence: 99%

“…A typical T2 distribution spectrum for brain tissue is shown in Figure 1.10. This technique has mostly been used in multi-exponential T2 relaxation (70,71,90,91), but also in T2* relaxation (85), and T1 relaxation (67). By estimating the relative sizes of the different components this has been used as a surrogate measure of myelin content in tissue, the myelin water fraction (MWF):…”

Section: Myelin Water Fractionmentioning

confidence: 99%

“…Furthermore, it is well known that brain tissues exhibit multi-exponential T1 (67) and T2 relaxation (70,71), reflecting the underlying water compartments in the microscopic environment. When a single mono-exponential relaxation is assumed, as is done in QMAP, the actual estimated values of T1 and T2 depend to some degree on the specific number of echoes used, the number of saturation delays, the echo times, and the saturation delay times.…”

Section: Limitationsmentioning

confidence: 99%

See 2 more Smart Citations

Quantitative Magnetic Resonance Imaging of the Brain : Applications for Tissue Segmentation and Multiple Sclerosis

West¹

2014

View full text Add to dashboard Cite

Magnetic resonance imaging (MRI) is a sensitive technique for assessing white matter (WM) lesions in multiple sclerosis (MS), but there is a low correlation between MRI findings and clinical disability. Because of this, other pathological changes are of interest, including changes in normal appearing white matter (NAWM) and diffusely abnormal white matter (DAWM). Even so, the mechanisms leading to permanent disability in MS remain unclear. In contrast to conventional MRI, quantitative MRI (qMRI) is aimed at the direct measurement of the physical tissue properties, such as the relaxation times, T1 and T2, as well as the proton density (PD). QMRI is promising for characterising and quantifying changes in MS and for brain tissue segmentation. The present work describes a novel method of qMRI for the human brain (QMAP), and a segmentation method based on this. The developed methods were validated in control subjects and MR phantoms. Furthermore, an application in diseased human brain was demonstrated in MS patients. In all, 50 healthy controls and 35 MS patients were scanned with qMRI in a total of 225 acquisitions. One major finding of this work was that qMRI was able to detect and quantify changes in the MS disease that were not visible using conventional MRI. In particular, it was found that DAWM appears to constitute an intermediate between focal white matter (WM) lesions and NAWM. These changes may be caused by pathological processes that are not entirely attributable to Wallerian degeneration. This study showed that the QMAP method had high accuracy and relatively high precision, within a clinically acceptable time. This work also demonstrated that qMRI could be used for brain tissue segmentation and volume estimation of the whole brain, using pre-defined tissue characteristics. The results showed that brain tissue segmentation had high repeatability, which was somewhat lower when different geometries were acquired or different field strengths used. In particular, small differences were found between 1.5 T and 3.0 T in deep brain structures, the cerebellum and the brain stem. This work leads the way for early clinical applications of qMRI, and the challenge for the years to come is to understand the connection between qMRI properties of the brain and underlying biology.Bildtagning med magnetresonanstomografi (MRT) är en teknik som kan användas för att upptäcka lesioner i vit substans hos patienter med multipel skleros (MS), men sambandet mellan lesioner och klinisk funktionsnedsättning är svagt. På grund av detta har intresset för andra patologiska processer i hjärnan ökat. Exempel är förändringar i vit substans som ser normal ut vid MRT (NAWM) och även så kallad diffus vit vävnad (DAWM). Det är emellertid fortfarande oklart vilka mekanismer i MS som leder till klinisk funktionsnedsättning. Med kvantitativ MRT (qMRT) kan fysiologiska egenskaper i vävnaden, som till exempel relaxationstiderna (T1 och T2) samt protontäthet (PD), mätas. QMRT kan användas för att mäta förändringar i hjärnan hos MS patienter och des...

show abstract

Hypomyelinating leukodystrophies: Translational research progress and prospects

Pouwels

Vanderver

Bernard

et al. 2014

Annals of Neurology

138

108

View full text Add to dashboard Cite

Hypomyelinating leukodystrophies represent a genetically heterogeneous but clinically overlapping group of heritable disorders. Current management approaches in the care of the patient with a hypomyelinating leukodystrophy include use of serial magnetic resonance imaging (MRI) to establish and monitor hypomyelination, molecular diagnostics to determine a specific etiology, and equally importantly, careful attention to neurologic complications over time. Emerging research in oligodendrocyte biology and neuroradiology with bedside applications may result in the possibility of clinical trials in the near term, yet there are significant gaps in knowledge in disease classification, characterization, and outcome measures in this group of disorders. Here we review the biological background of myelination, the clinical and genetic variability in hypomyelinating leukodystrophies, and the insights that can be obtained from current MRI techniques. In addition, we discuss ongoing research approaches to define potential outcome markers for future clinical trials. ANN NEUROL 2014;76:5-19 T he concept of hypomyelinating disorders was originated by Schiffmann, van der Knaap, and colleagues.1-3 Among the inherited white matter (WM) disorders, hypomyelinating leukodystrophies (HLDs) are notable for abnormalities in myelin development rather than destruction. This class of disorders is distinguished by their characteristic appearance on magnetic resonance imaging (MRI), namely, lessening or absence of the T 2 hypointensity that typically signifies the presence of myelin, often without the significant lessening of T 1 hyperintensity seen in the other, nonhypomyelinating leukodystrophies. Other MRI features help to narrow the differential diagnosis and focus genetic and metabolic testing. 3 We are entering a phase of clinical research for HLDs where identification of outcome measures of potential treatment benefit is crucial. In ultrarare diseases, clinical features, and natural history are often This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. poorly known; therefore, clinical/neurological parameters alone are insufficient as endpoints for clinical efficacy studies. In this case, another possible acceptable clinical trial design includes the use of biomarkers as surrogate endpoints. The adoption of criteria for biomarkers of efficacy is an important feasibility step for the planning and execution of clinical studies because it provides an objective endpoint at a defined period of time after an intervention has been initiated. Proposing a standard measure of myelination based upon magnetic resonance (MR) metrics as a reliable biomarker could therefore greatly encourage clinical research.With these challenges in mind, we organized a multidisciplinary group to address clinical and future research priorities for HLDs. The group ...

show abstract

Myelin water mapping by spatially regularized longitudinal relaxographic imaging at high magnetic fields

Abstract: The short-T1 fraction is interpreted as the water resident in myelin. Its detection is facilitated by longer T1 of axoplasmic water at higher magnetic field.

Cited by 116 publications

References 68 publications

Matrix-algebra-based calculations of the time evolution of the binary spin-bath model for magnetization transfer

Matrix-algebra-based calculations of the time evolution of the binary spin-bath model for magnetization transfer

Quantitative Magnetic Resonance Imaging of the Brain : Applications for Tissue Segmentation and Multiple Sclerosis

Hypomyelinating leukodystrophies: Translational research progress and prospects

Contact Info

Product

Resources

About