title: Variations in signal intensity with periodical temperature changes in vivo in rat brain: analysis using wide-field optical coherence tomography.
abstract: In a previous study, we reported measurements of three-dimensional (3D) optical coherence tomography (OCT) images through a thinned skull by reducing temperatures from 28 °C to 18 °C in vivo in the rat brain to show negative correlation coefficients (CCs) between ratios of signal intensity (RSI) and temperature for applications to monitoring brain viability. In this study, using the same OCT system, we measured 3D OCT images of the rat brain by periodically changing tissue temperatures from 20 °C to 32 °C in vivo. In the evaluation of CCs among RSI, temperature, and heart rate, the largest number of periods was four, and the longest measurement time was 570 min. Averaged CCs between RSI and temperature, and between RSI and heart rate, were -0.42 to -0.50 and -0.48 to -0.64, respectively. RSI reversibly changed subsequent variations of temperatures and finally increased rapidly just before cardiac arrest. These results indicate that RSI could correspond to decreases in viability because of local ischemia and recovery.
authors.affiliation: Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata, Japan. msato@yz.yamagata-u.ac.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Sato
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nomura
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Kitano
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsunenari
authors.forename: Izumi
authors.initials: I
authors.lastname: Nishidate
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D041623:Tomography, Optical Coherence / Q000379:methods*