Intravoxel incoherent motion (IVIM) imaging at different magnetic field strengths: What is feasible?

Rydhög, Anna; Osch, Matthias J.P. van; Lindgren, Emelie; Nilsson, Markus; Lätt, Jimmy; Ståhlberg, Freddy; Wirestam, Ronnie; Knutsson, Linda

doi:10.1016/j.mri.2014.07.013

Cited by 28 publications

(56 citation statements)

References 41 publications

(48 reference statements)

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“…The extent of the perfusion effects was demonstrated by the in vivo human data, for which the observed levels of f b with the comprehensive acquisition were between 1% and 3% in most (30 of 43) white matter ROIs, which is in accordance with previous studies (32, 45). However, as predicted by the simulations, even though f b had low values, the effect on the estimation of f w was considerable.…”

Section: Discussionsupporting

confidence: 89%

“…Moreover, the fractional volume parameters are weighted by the T1 and T2 relaxation times, which are not accounted for in the current model. Previous studies have shown that relaxation compensation could be included in the IVIM model (32, 58, 59) to get a better estimation of the fractional volumes and to separate the different components. However, this will significantly increase the acquisition time, as well as the number of model parameters.…”

Section: Discussionmentioning

confidence: 99%

“…With data acquired at multiple b -values, the two-compartment IVIM model allows estimation of f b . In previous studies, estimates of the average f b in healthy white matter varied between 3.3% (32) to as high as 16% (at low SNR) (18), with a number of studies reporting average fb of around 5% (19, 20, 33). The rapidly attenuated signal component arising from perfusion is detectable only at low b -values, while the slower attenuation of water molecules in or around brain tissue is identified at higher b -values.…”

Section: Methodsmentioning

confidence: 99%

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Separating blood and water: Perfusion and free water elimination from diffusion MRI in the human brain

et al. 2017

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The assessment of the free water fraction in the brain provides important information about extracellular processes such as atrophy and neuroinflammation in various clinical conditions as well as in normal development and aging. Free water estimates from diffusion MRI are assumed to account for freely diffusing water molecules in the extracellular space, but may be biased by other pools of molecules in rapid random motion, such as the intravoxel incoherent motion (IVIM) of blood, where water molecules perfuse in the randomly oriented capillary network. The goal of this work was to separate the signal contribution of the perfusing blood from that of free-water and of other brain diffusivities. The influence of the vascular compartment on the estimation of the free water fraction and other diffusivities was investigated by simulating perfusion in diffusion MRI data. The perfusion effect in the simulations was significant, especially for the estimation of the free water fraction, and was maintained as long as low b-value data were included in the analysis. Two approaches to reduce the perfusion effect were explored in this study: (i) increasing the minimal b-value used in the fitting, and (ii) using a three-compartment model that explicitly accounts for water molecules in the capillary blood. Estimation of the model parameters while excluding low b-values reduced the perfusion effect but was highly sensitive to noise. The three-compartment model fit was more stable and additionally, provided an estimation of the volume fraction of the capillary blood compartment. The three-compartment model thus disentangles the effects of free water diffusion and perfusion, which is of major clinical importance since changes in these components in the brain may indicate different pathologies, i.e., those originating from the extracellular space, such as neuroinflammation and atrophy, and those related to the vascular space, such as vasodilation, vasoconstriction and capillary density. Diffusion MRI data acquired from a healthy volunteer, using multiple b-shells, demonstrated an expected non-zero contribution from the blood fraction, and indicated that not accounting for the perfusion effect may explain the overestimation of the free water fraction evinced in previous studies. Finally, the applicability of the method was demonstrated with a dataset acquired using a clinically feasible protocol with shorter acquisition time and fewer b-shells.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Separating blood and water: Perfusion and free water elimination from diffusion MRI in the human brain

et al. 2017

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“…Several groups have investigated the reproducibility of conventional IVIM and have shown good results (eg, low coefficients of variation [CVs]) for both the perfusion volume fraction and parenchymal diffusivity. [12][13][14][15] Thus far, only 1 reproducibility study has been performed on IR-IVIM. This study examined only f and healthy participants.…”

Section: Discussionmentioning

confidence: 99%

“…[12][13][14][15] In patients with gliomas, CVs of 6.5% and 0.6% in the NAWM outside the tumor mass for f and D were reported, respectively. 12 Furthermore,…”

Section: Discussionmentioning

confidence: 99%

On the Reproducibility of Inversion Recovery Intravoxel Incoherent Motion Imaging in Cerebrovascular Disease

Wong¹,

Backes²,

Zhang

et al. 2017

AJNR Am J Neuroradiol

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Modified triexponential analysis of intravoxel incoherent motion for brain perfusion and diffusion

Ohno

Miyati

Kobayashi

et al. 2015

J. Magn. Reson. Imaging

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Intravoxel incoherent motion (IVIM) imaging at different magnetic field strengths: What is feasible?

Cited by 28 publications

References 41 publications

Separating blood and water: Perfusion and free water elimination from diffusion MRI in the human brain

Separating blood and water: Perfusion and free water elimination from diffusion MRI in the human brain

On the Reproducibility of Inversion Recovery Intravoxel Incoherent Motion Imaging in Cerebrovascular Disease

Modified triexponential analysis of intravoxel incoherent motion for brain perfusion and diffusion

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