@article{oai:repo.qst.go.jp:00044836,
 author = {Ibaraki, Masanobu and Ito, Hiroshi and Simosegawa, Masayuki and Ishigami, Keiichi and Takahashi, Kazuhiro and Kanno, Iwao and et.al and 伊藤 浩 and 下瀬川 正幸 and 高橋 和弘 and 菅野 巖},
 issue = {2},
 journal = {Journal of Cerebral Blood Flow and Metabolism},
 month = {Feb},
 note = {Cerebral vascular mean transit time (MTT), defined as the ratio of cerebral blood volume to cerebral blood flow (CBV/CBF), is a valuable indicator of the cerebral circulation. Positron emission tomography (PET) and dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) are useful for the quantitative determination of MTT in the clinical setting. The aim of this study was to establish a normal value set of MTT as determined by PET and by DSC-MRI and to identify differences between these methods. Seven healthy volunteers were studied with (15)O-PET (H(2)(15)O and C(15)O) and gradient-echo echo-planar DSC-MRI at 1.5 T. In the DSC-MRI study with bolus injection of contrast agent, deconvolution analysis was performed. Comparison of gray-to-white matter ratios showed fairly good agreement between PET and DSC-MRI for all parameters (relative CBV, relative CBF, and relative MTT), confirming the validity of relative measurements with DSC-MRI. However, quantitative MTT measured by DSC-MRI was significantly shorter than that measured by PET in cerebral cortical regions (2.8 to 3.0 secs for DSC-MRI versus 3.9 to 4.3 secs for PET) and the centrum semiovale (3.5 secs for DSC-MRI versus 4.8 secs for PET). These discrepancies may be because of the differences in the intrinsic sensitivity of each imaging modality to vascular components; whereas PET measurement of CBV is equally sensitive to all vascular components, measurement with DSC-MRI originates from the microvasculature in the vicinity of the brain parenchyma. This underlying difference may influence interpretation of MTT determined by PET or by DSC-MRI for patients with cerebrovascular disease.},
 pages = {404--413},
 title = {Cerebral vascular mean transit time in healthy humans: a comparative study with PET and dynamic susceptibility contrast-enhanced MRI.},
 volume = {27},
 year = {2007}
}