Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis

Bammer, Roland; Augustin, Michael; Strasser-Fuchs, Siegrid; Seifert, Thomas; Kapeller, Peter; Stollberger, Rudolf; Ebner, Franz; Hartung, Hans‐Peter; Fazekas, Franz

doi:10.1002/1522-2594(200010)44:4<583::aid-mrm12>3.0.co;2-o

Cited by 244 publications

(189 citation statements)

References 21 publications

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“…All studies [6][7][8][9][10] have shown, perhaps not surprisingly, that the mean diffusivity is elevated in lesions seen on T 2 -weighted scans. The degree of elevation seems to depend somewhat on the clinical course of the patient, but can be as high as 250%, with some lesions having diffusivity close to that of pure water at body temperature.…”

Section: Elevated Diffusivity In Lesionsmentioning

confidence: 92%

“…Two recent studies show that diffusion anisotropy is generally reduced in MS lesions. 8,9 However, one study showed the lowest anisotropy in acute inflammatory lesions, 8 while the other showed that T 1 -hypointense lesions (black holes) have the lowest anisotropy. 9 Figure 1 shows T 1 -weighted, T 2 -weighted and diffusion tensor images obtained by Werring et al 8 in an MS patient (reproduced with permission), in which a ringenhancing lesion is clearly evident on T 2 -weighted and post-contrast T 1 -weighted images [ Fig.…”

Section: Reduced Diffusion Anisotropymentioning

confidence: 95%

“…These include lesions that are hypointense on T 1 -weighted scans (black holes) and lesions with low magnetisation transfer ratio (MTR) values: those lesions with more destructive pathology are generally shown to have the most strongly elevated diffusivity. [6][7][8][9][10]13 Elevated diffusivity in normal-appearing white matter A pattern of slightly elevated diffusivity, evident from even the earliest work, strongly suggests that there are abnormalities in the so-called normal-appearing white matter (NAWM) between the T 2 -visible lesions. The elevation in diffusivity of around 4-8% (Table 1) in NAWM suggests that either MS is a diffuse WM disease as well as multi-focal in nature, or the WM is subject to Wallerian degeneration proximal and distal to the visible lesions.…”

Section: Elevated Diffusivity In Lesionsmentioning

confidence: 99%

“…The fractional anisotropy image [ Fig. 1(c)] exquisitely 6 12.7% Werring et al 8 4.8% Bammer et al 9 3.5% Filippi et al 14 12.9%…”

Section: Reduced Diffusion Anisotropymentioning

confidence: 99%

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Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

2002

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This paper reviews the current applications of diffusion-weighted and diffusion tensor MRI in diseases of the brain white matter. The contribution that diffusion-weighted imaging has made to our understanding of white matter diseases is critically appraised. The quantitative nature of diffusion MRI is one of its major attractions; however, this is offset by the more advanced hardware required to collect diffusion-weighted images reliably, and the more complex processing to produce quantitative parametric diffusion images. With the now common availability of scanners equipped to perform echo-planar imaging, the acquisition of diffusion tensor images is sure to become more widespread and routine.

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Section: Elevated Diffusivity In Lesionsmentioning

confidence: 92%

Section: Reduced Diffusion Anisotropymentioning

confidence: 95%

Section: Elevated Diffusivity In Lesionsmentioning

confidence: 99%

“…The fractional anisotropy image [ Fig. 1(c)] exquisitely 6 12.7% Werring et al 8 4.8% Bammer et al 9 3.5% Filippi et al 14 12.9%…”

Section: Reduced Diffusion Anisotropymentioning

confidence: 99%

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Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

2002

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“…We investigated the impact of variations in the intercompartmental water exchange rate on multicomponent T 2 , and on two-pool parameter estimates from pulsed MT. Since diffusivity increases of up to 50% are reported in the MS literature (29)(30)(31), the effect of increased exchange from potential pathologic changes was simulated by increases in the water exchange rate (R D ) of 25, 50, and 100%. Simulations were also performed at the fast-and slow-exchange limits (R D 3 0 and R D ϭ 10 4 sec -1 , respectively).…”

Section: Modification Of the Modelmentioning

confidence: 99%

Characterizing healthy and diseased white matter using quantitative magnetization transfer and multicomponent T₂ relaxometry: A unified view via a four‐pool model

Levesque

Pike

2009

Magnetic Resonance in Med

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Nuclear magnetic resonance relaxation and magnetization transfer in cerebral white matter can be described using a four-pool model: two for water protons (in separate myelin and intra/extracellular compartments) and two for protons associated with the lipids and proteins of biologic membranes (of myelin and nonmyelin semisolids). This model was used to gain insight into the observations from multicomponent quantitative T 2 relaxometry and quantitative magnetization transfer imaging, both based on simplified white matter models and experimentally feasible in vivo. The sensitivity of MRI to white matter (WM) damage in diseases such as multiple sclerosis (MS) has made it indispensable in diagnosis, but its lack of pathologic specificity remains problematic. In response, investigators have turned to quantitative MRI techniques to identify putative indicators of specific pathologic features, such as myelin loss. Quantitative analysis of spin-spin relaxation data using T 2 distributions (QT2), also known as myelin water imaging, can notably distinguish two major T 2 components in human WM (1,2). In particular, QT2 yields an estimate of the myelin water fraction (MWF), the fraction of water contained between the layers of myelin in WM. Magnetization transfer (MT) imaging (3,4), most often measured as the MT ratio, is a widely available technique that is sensitive to the semisolid constituents of tissue (e.g., lipids, proteins), and in WM the MT effect is believed to be dominated by myelin (5). The MT ratio is a semiquantitative index that presents a limited view of the MT effect. More detailed analysis of pulsed, off-resonance MT data using the two-pool model of tissue (6,7) has been extended to in vivo imaging, in particular in human WM (8-10). The resulting method, termed quantitative MT imaging (QMTI), allows mapping of the parameters of the two-pool (liquid and semisolid) model of tissue: the ratio of semisolid to liquid protons F, the first-order forward and reverse exchange rate constants k f and k r (where k r ϭ k f /F), the spin-lattice relaxation rate R 1f of the free pool (R 1f ϭ 1/T 1f ), the spin-spin relaxation time constant of the free pool T 2f , and the "T 2 " of the restricted pool, T 2r (inversely related to the width of the restricted pool resonance). Separating the fundamental parameters of the two-pool model requires an additional measurement of the "long" observed T 1 (T 1obs ), from which the free pool R 1f can then be computed (6). The MWF, MT ratio, and certain QMTI parameters have respectively been shown to correlate with myelin content and demyelination (11-13).QT2 and QMTI techniques each present a different limited view of WM characteristics. QT2 imaging relies on the fundamental assumptions that water exists in isolated compartments and that variations in the estimated MWF are equal to variations in myelin. On the other hand, the two-pool model for MT neglects the existence of multiple water pools. A more comprehensive model for WM that includes four communicating proton pools (myelin soli...

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Progressive Gray Matter Damage in Patients With Relapsing-Remitting Multiple Sclerosis

Oreja‐Guevara¹,

Rovaris²,

Iannucci³

et al. 2005

Arch Neurol

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Background: Diffusion tensor magnetic resonance imaging (DT MRI) has the potential to provide in vivo information about tissue microstructure. In multiple sclerosis (MS), DT MRI has disclosed the presence of occult structural damage in the normal-appearing brain tissues.Objective: To investigate whether DT MRI is sensitive to longitudinal changes of brain damage that may occur beyond the resolution of T2-weighted images in patients with relapsing-remitting MS.Design: Twenty-six untreated patients with relapsingremitting MS were followed up for 18 months. Dualecho, DT and postcontrast T1-weighted MRIs of the brain were obtained at baseline and then every 3 months. Mean diffusivity (D ) histograms of normal-appearing gray (GM) and white matter were produced. Total T2hyperintense and T1-hypointense lesion volumes; normalized whole brain tissue, GM, and white matter volumes; percentage brain volume change between the study entry and exit images; average lesion D ; and fractional anisotropy were also calculated.Results: During the study period, a significant decrease of normalized whole brain tissue, average lesion fractional anisotropy and normal-appearing GM D histogram peak height, and a significant increase of average normal-appearing GM D and T2-hyperintense lesion volumes were observed. Changes of normalappearing GM diffusivity were independent of the concomitant changes of normalized whole brain tissue and GM volumes. Conclusions:The DT MRI findings show progressive microstructural changes in the normal-appearing GM of patients with untreated relapsing-remitting MS. Such changes do not reflect a concomitant development of brain atrophy and confirm the importance of GM pathology in MS.

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Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis

Cited by 244 publications

References 21 publications

Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

Characterizing healthy and diseased white matter using quantitative magnetization transfer and multicomponent T₂ relaxometry: A unified view via a four‐pool model

Progressive Gray Matter Damage in Patients With Relapsing-Remitting Multiple Sclerosis

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Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis

Cited by 244 publications

References 21 publications

Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

Applications of diffusion‐weighted and diffusion tensor MRI to white matter diseases – a review

Characterizing healthy and diseased white matter using quantitative magnetization transfer and multicomponent T2 relaxometry: A unified view via a four‐pool model

Progressive Gray Matter Damage in Patients With Relapsing-Remitting Multiple Sclerosis

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Product

Resources

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Characterizing healthy and diseased white matter using quantitative magnetization transfer and multicomponent T₂ relaxometry: A unified view via a four‐pool model