Kimihiro Ogisu1,
Akiko Fujita2, Toru Yamamoto3
1Department
of Radiology, National Hospital Organization Hokkaido Medical Center,
Sapporo, Hokkaido, Japan; 2Graduate School of Health Sciences,
Hokkaido University, Sapporo, Hokkaido, Japan; 3Faculty of Health
Sciences, Hokkaido University, Sapporo, Hokkaido, Japan
Blood flow in capillaries has been believed to be intravoxel incoherent motion whose MR signal appears in diffusion weighted imaging at low b values as well as MR signal from free water. However, we found an increase in T2 with decreasing b values, and this increase cannot be interpreted by blood in capillaries. MR signal from interstitial fluid (ISF), the T2 of which is around 300 ms, agrees the T2 increase. Blood flow in capillaries is rather understood as intravoxel coherent motion by using anisotropic directional distribution model of vessel segments.