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• Original Article •
Changes in relaxation value and cerebral blood flow observed in rat brain with delivery of pure oxygen under 7.0 T
GAO Xin  TANG Wei-jun  WANG Xia  LIU Shi-yuan  TAO Xiao-feng 

DOI:10.3969/j.issn.1674-8034.2010.06.013.


[Abstract] Objective: To compare the changes in relaxation value of the cortex, striatum and corpus callosum in rats, and clarify the relationship between the cerebral blood flow (CBF) and changes in relaxation value during hyperoxia.Materials and Methods: Twelve male Sprague-Dawley rats weighting 200-250g were examined with 7.0 T MR scanner. T1, T2 and T2* value of the cortex, striatum and corpus callosum were determined in air, respectively. After the air changed to 100% oxygen, T1, T2 and T2* value were determined again. Percentage changes in all values were compared. Changes in CBF value between the cerebral cortex and striatum in frontal lobe were also compared using the FAIR sequence in eight male rats.Results: Compared with room air, T1 values of the cortex, striatum and corpus callosum decreased obviously, whereas significant T2 and T2* prolongation of which was demonstrated. Percentage changes in all values between the cortex, striatum and corpus callosum were different (P<0.001) when exposed to 100% oxygen. Percentage changes of T1 and T2* value was respectively biggest in the cortex, whereas that of T2 value was biggest in the corpus callosum. The decrease of CBF value was more obvious in the cerebral cortex than that of striatum.Conclusion: Using 7.0 T MR scanner permits getting higher spatial resolution and more reliable experiment data. The shortening T1 was induced by the increased amount of paramagnetic free oxygen. The contribution of reduction of CBF was negligible in changes to T1 and T2* value. The prolonging T2 and T2* was caused by the increased fraction of oxyhaemoglobin. The different T2 percentage changes between the cortex, striatum and corpus callosum may be decided by the distribution of vascular population. Administered 100% oxygen was shown to be effective as a exogenous 'contrast agent’ on high field MRI system that can be used as a new method to study the cerebrovascular responses.
[Keywords] Brain；Relaxation value；Oxygen；Magnetic resonance imaging；Cerebral blood flow

GAO Xin Department of Radiology, Changzheng Hospital Affiliated to the Second Military Medical University, Shanghai 200052, China

TANG Wei-jun Department of Radiology, Changzheng Hospital Affiliated to the Second Military Medical University, Shanghai 200052, China

WANG Xia Department of Radiology, Changzheng Hospital Affiliated to the Second Military Medical University, Shanghai 200052, China

LIU Shi-yuan Department of Radiology, Changzheng Hospital Affiliated to the Second Military Medical University, Shanghai 200052, China

TAO Xiao-feng* Department of Radiology, Changzheng Hospital Affiliated to the Second Military Medical University, Shanghai 200052, China

*Correspondence to: Tao XF, E-mail: cjr.taoxiaofeng@vip.163.com

Conflicts of interest   None.

致谢： 感谢东南大学江苏省分子影像与功能成像重点实验室提供7.0 T磁共振成像扫描仪，以及在实验中给予的帮助。
Received  2010-06-07
Accepted  2010-09-06
DOI: 10.3969/j.issn.1674-8034.2010.06.013
DOI:10.3969/j.issn.1674-8034.2010.06.013.

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