2006 Fiscal Year Final Research Report Summary
Development of brain functional imaging using hyperpolarized Xe
| Project/Area Number |
17390340
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Radiation science
|
|---|
| Research Institution | Research Institute for Brain and Blood Vessels-Akita |
|---|
Principal Investigator |
KONDOH Yasushi Research Institute for Brain and Blood Vessels-Akita, Department of Neurology, Senior Scientist, 神経内科学研究部, 主任研究員 (70360360)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KANNO Iwao Research Institute for Brain and Blood Vessels-Akita, Research Bureau, Vice-director, 研究局, 副研究局長 (10360356)
IBARAKI Masanobu Research Institute for Brain and Blood Vessels-Akita, Department of Radiology, Researcher, 放射線医学研究部, 研究員 (40360359)
MIZUSAWA Shigenori Research Institute for Brain and Blood Vessels-Akita, Department of Internal Medicine, Researcher, 内科学研究部, 研究員 (80360361)
KADO Hirotsugu Research Institute for Brain and Blood Vessels-Akita, Department of Radiology, Researcher, 放射線医学研究部, 研究員 (10334830)
NAKAMURA Kazuhiro Research Institute for Brain and Blood Vessels-Akita, Department of Radiology, Researcher, 放射線医学研究部, 研究員 (10312638)
|
|---|
| Project Period (FY) |
2005 – 2006
|
| Keywords | NMR / Hyperpolarize Xe / tissue longitudinal decay / Cerebral Blood Flow / MRI |
|---|
| Research Abstract |
Hyperpolarized 129Xe has the potential to be an NMR tracer with a decay time of 10-25 s in blood and in tissue. Since the decay time of 129Xe in rat brain is affected by both cerebral blood flow (CBF) and longitudinal decay (T1) in brain, making a precise measurement of in vivo 129Xe T1 is difficult. At first, T1 in brain is estimated using an alternative method of perturbing and measuring CBF. Since it has been shown that blood PaCO_2 is a reliable indicator of CBF,CO_2 inhalation and blood gas sampling were used to observe CBF. The rate of signal decay is sensitive to changes in CBF. Parameter estimates were obtained with least-squares fitting of the data to the equation log(S2/S1)=K-ΔTR/T1+ΔTR α PaCO2,with α being an unknown constant of proportionality between CBF and PaCO_2. Uncertainty in the parameter estimates was evaluated using bootstrap resampling. It was found that T1=18.3 s with a 95% confidence interval (13.8,25.0) s
Secondly, we applied it to detect neural activation in human. Chemical shift imaging was performed with a 1.5T MRI obtaining in 5x5 matrixes. Measurements were carried out with an 8Hz-reversing checkerboard and a fixed-point pattern used as a control. The main and second peaks are at 195 and 192 ppm with respect to the gas peak. We found a relative increase of 1.37+/-0.17 for the main peak and 1.26+/-0.23 for the second peak. Assuming that the main and second peaks correspond to gray and white matter, respectively, and that the peak height mainly reflects increased delivery of HpXe due to an increase in blood flow, the relative increase in evoked CBF is approximately the same in both gray and white matter.
|
Research Products
(14 results)
