Ho Sung Kim1
1Asan Medical Center, Seoul, Korea, Republic of
Synopsis
Intravoxel incoherent motion (IVIM)
magnetic resonance imaging technique aims to separate water molecule diffusion
(D) component and microvascular perfusion or pseudo‐diffusion (D*) component in the diffusion‐weighted (DW) signals of tissues. Perfusion‐related information (pseudo‐diffusion D*, perfusion fraction F) was shown to be able to diagnose
brain tumors. Because D values is not reliant on the effects of perfusion, the
state of diffusion can be more accurately depicted than through conventional
ADC measurements. IVIM does not require the use of intravenous contrast agents
and can, therefore, be administered to children, pregnant women, patients with
a previous anaphylactic reaction to gadolinium-based contrast agents.
Intravoxel Incoherent Motion in Brain Tumor Imaging
Intravoxel incoherent motion (IVIM)
magnetic resonance imaging technique, initially introduced by Le Bihan et al.
aims to separate water molecule diffusion (D) component and microvascular
perfusion or pseudo‐diffusion (D*)
component in the diffusion‐weighted (DW)
signals of tissues. Perfusion‐related
information (pseudo‐diffusion D*,
perfusion fraction F) was shown to be able to diagnose brain tumors, such as
tumor grading and differentiation of recurrent tumors from posttreatment
effects. The lower the ADC value is, the higher the tumor cell density is, and
D* and f represent microangiogenesis; the greater the D* and f values, the more
microvessels. The proliferation of tumor cell density and microvessels may
predict the poor prognosis of the patients.
However, reliable estimation of perfusion‐related parameters is a
persistent problem. Nonlinear least squares method does not take into account the independent characterization of
diffusion and perfusion components. Segmented least squares fitting causes bias
errors due to the assumption on the influence of D* at high b‐values. More recently, Bayesian methods have been proposed to solve
the regression problem in a probabilistic manner.
Because D values are based on a model that
is not reliant on the effects of perfusion, the state of diffusion can be more
accurately depicted than through conventional ADC measurements. IVIM does not
require the use of intravenous contrast agents and can, therefore, be
administered to children, pregnant women, patients with a previous anaphylactic
reaction to gadolinium-based contrast agents.Acknowledgements
No acknowledgement found.References
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Grenier P, Cabanis E, Laval‐Jeantet M MR
imaging of intravoxel incoherent motions: application to diffusion and
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2. Bisdas S, Koh TS, Roder C, et al.
Intravoxel incoherent motion diffusion‐weighted MR imaging of gliomas: feasibility of the method and
initial results. Neuroradiology. 2013; 55: 1189– 1196.
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Histogram analysis of intravoxel incoherent motion for differentiating
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clinical experience. Am J Neuroradiol. 2014; 35: 490– 497.