title: Laser speckle imaging reveals multiple aspects of cerebral vascular responses to whole body mild hypothermia in rats.
abstract: In this paper, we present a novel method to study the effect of induced mild hypothermia on cerebral vascular responses. To measure cerebral vascular responses, a minimally invasive imaging method, temporal laser speckle imaging, was developed and adapted for induced-hypothermia rat model. Experiments were carried out in rats under anesthesia. Laser speckle images were acquired at different temperature points, normothermia (37 °Q and mild therapeutic hypothermia (34 °Q. We extracted multiple hemodynamic responses simultaneously from the images, including blood flow, vessel size and deoxy-hemoglobin saturation. A wide-field view of the cerebral vascular response distribution was studied, which showed an inhomogeneous response map across the region of interest. A comparison between responses in arterioles and venules was carried out (blood flow decreased by 58 ± 9 % vs. 27 ± 8 %). The global decrease of blood flow, dilatation in arterioles and decrease of deoxy-hemoglobin saturation in veins at mild hypothermia suggests a beneficial role of circulatory and oxygenation changes in therapeutic hypothermia. The results reported provide a circulatory explanation for the hypothermia therapeutic effects and mechanism.
authors.affiliation: Biomedical Engineering Department, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA. nanli@jhu.edu
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Nitish V
authors.initials: NV
authors.lastname: Thakor
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Jia
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001921:Brain / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007035:Hypothermia / Q000175:diagnosis* / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation*; D007834:Lasers; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity