Hye-Young Heo1,
2, Casey P. Johnson1, Daniel R. Thedens1, John A.
Wemmie3, 4, Vincent A. Magnotta1, 3
1Department
of Radiology, University of Iowa, Iowa City, IA, United States; 2Department
of Biomedical Engineering, University of Iowa, Iowa City, IA, United States; 3Department
of Psychiatry, University of Iowa, Iowa City, IA, United States; 4Department
of Neurosurgery, University of Iowa, Iowa City, IA, United States
The purpose of this study is to measure the change of T1ρ response to the activity-dependent localized acidosis. We used a flashing checkerboard with different temporal frequencies of 1, 4, and 7Hz to evaluate if dynamicT1ρ imaging responds to the varied degree of neuronal activity. In addition, 31P spectroscopy was used to validate pH changes in visual cortex during visual fixation and visual stimulation with the different temporal frequencies. We found that the magnitude of the T1ρ response was proportional to the stimulus intensity induced by the change of the temporal frequencies. Furthermore, brain pH estimated by 31P spectroscopy in the visual cortex was found to decrease with the temporal frequency. Consequently, it suggests that T1ρ and pH changes depend on the degree of neuronal activity.
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