Intravoxel incoherent motion
To overcome a limitation of Diffusion weighted magnetic resonance imaging DWI in glioma diagnosis, which is that perfusion can substantially confound diffusion measurements because of the incoherent motion of blood, intravoxel incoherent motion (IVIM) based on DWI is proposed 1) 2)
Intravoxel incoherent motion (IVIM) imaging is a concept and a method initially introduced and developed by Le Bihan et al. to quantitatively assess all the microscopic translational motions that could contribute to the signal acquired with Diffusion weighted magnetic resonance imaging. In biological tissue, these motions essentially are molecular diffusion of water and microcirculation of blood in the capillary network (perfusion). The concept introduced by D. Le Bihan is that water flowing in randomly oriented capillaries (at the voxel level) mimics a random walk (“pseudo-diffusion”)
It is responsible for a signal attenuation in diffusion MRI, which depends on the velocity of the flowing blood and the vascular architecture. Similarly to molecular diffusion, the effect of pseudodiffusion on the signal attenuation depends on the b value. However, the rate of signal attenuation resulting from pseudodiffusion is typically an order of magnitude greater than molecular diffusion in tissues, so its relative contribution to the diffusion-weighted MRI signal becomes significant only at very low b values, allowing diffusion and perfusion effects to be separated.
A study reported a first attempt to address this issue, only parameter differences between low grade glioma and high grade gliomas were reported, and there was no information regarding the suitable cutoff values of the suggested differentiating parameters 3).
This imaging is useful in differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs) 4) 5).
Intravoxel incoherent motion (IVIM) imaging is a concept and a method initially introduced and developed by Le Bihan et al. to quantitatively assess all the microscopic translational motions that could contribute to the signal acquired with Diffusion weighted magnetic resonance imaging. In biological tissue, these motions essentially are molecular diffusion of water and microcirculation of blood in the capillary network (perfusion). The concept introduced by D. Le Bihan is that water flowing in randomly oriented capillaries (at the voxel level) mimics a random walk (“pseudo-diffusion”)
It is responsible for a signal attenuation in diffusion MRI, which depends on the velocity of the flowing blood and the vascular architecture. Similarly to molecular diffusion, the effect of pseudodiffusion on the signal attenuation depends on the b value. However, the rate of signal attenuation resulting from pseudodiffusion is typically an order of magnitude greater than molecular diffusion in tissues, so its relative contribution to the diffusion-weighted MRI signal becomes significant only at very low b values, allowing diffusion and perfusion effects to be separated.
A study reported a first attempt to address this issue, only parameter differences between low grade glioma and high grade gliomas were reported, and there was no information regarding the suitable cutoff values of the suggested differentiating parameters 3).
This imaging is useful in differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs) 4) 5).
1) Luciani A. et al. Liver cirrhosis: intravoxel incoherent motion MR imaging–pilot study. Radiology 249, 891–899, 10.1148/radiol.2493080080 (2008).
2) Le Bihan D. et al. Separation of diffusion and perfusion in intravoxel incoherent motion MR imaging. Radiology 168, 497–505, 10.1148/radiology.168.2.3393671 (1988).
3) Bisdas S. et al. Intravoxel incoherent motion diffusion-weighted MR imaging of gliomas: feasibility of the method and initial results. Neuroradiology 55, 1189–1196, 10.1007/s00234-013-1229-7 (2013).
4) Hu YC, Yan LF, Wu L, Du P, Chen BY, Wang L, Wang SM, Han Y, Tian Q, Yu Y, Xu TY, Wang W, Cui GB. Intravoxel incoherent motion diffusion-weighted MR imaging of gliomas: efficacy in preoperative grading. Sci Rep. 2014 Dec 1;4:7208. doi: 10.1038/srep07208. PubMed PMID: 25434593; PubMed Central PMCID: PMC4248278.
5) Togao O, Hiwatashi A, Yamashita K, Kikuchi K, Mizoguchi M, Yoshimoto K, Suzuki SO, Iwaki T, Obara M, Van Cauteren M, Honda H. Differentiation of high-grade and low-grade diffuse gliomas by intravoxel incoherent motion MR imaging. Neuro Oncol. 2015 Aug 4. pii: nov147. [Epub ahead of print] PubMed PMID: 26243792.