The Brain Thermal Response as a Potential Neuroimaging Biomarker of Cerebrovascular Impairment

• Published in: American journal of neuroradiology : AJNR 2017-11, Vol.38 (11), p.2044-2051
• Main Authors: Fleischer, C C, Wu, J, Qiu, D, Park, S-E, Nahab, F, Dehkharghani, S
• Format: Article
• Language: English
• Subjects: Acetazolamide; Acetazolamide - therapeutic use; Adult; Adult Brain; Aged; Biomarkers; Blood circulation; Body Temperature; Brain; Brain - physiopathology; Carbonic Anhydrase Inhibitors - therapeutic use; Cerebrovascular Circulation; Cerebrovascular Disorders - diagnostic imaging; Cerebrovascular Disorders - physiopathology; Coefficients; Editor's Choice; Female; Hemodynamics; Historical account; Homeostasis; Humans; Impairment; Invasiveness; Labeling; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Mathematical models; Medical imaging; Metabolism; Middle Aged; Neuroimaging; Neuroimaging - methods; Neurology; Oxygen - blood; Patients; Perfusion; Reactivity; Retrospective Studies; Spin labeling; Spin Labels; Temperature; Temperature effects; Thermal imaging; Thermal response; Thermometry - methods
• ISSN: 0195-6108; 1936-959X
• DOI: 10.3174/ajnr.a5380

Brain temperature is critical for homeostasis, relating intimately to cerebral perfusion and metabolism. Cerebral thermometry is historically challenged by the cost and invasiveness of clinical and laboratory methodologies. We propose the use of noninvasive MR thermometry in patients with cerebrovascular disease, hypothesizing the presence of a measurable brain thermal response reflecting the tissue hemodynamic state. Contemporaneous imaging and MR thermometry were performed in 10 patients (32-68 years of age) undergoing acetazolamide challenge for chronic, anterior circulation steno-occlusive disease. Cerebrovascular reactivity was calculated with blood oxygen level-dependent imaging and arterial spin-labeling methods. Brain temperature was calculated pre- and post-acetazolamide using previously established chemical shift thermometry. Mixed-effects models of the voxelwise relationships between the brain thermal response and cerebrovascular reactivity were computed, and the significance of model coefficients was determined with an test ( < .05). We observed significant, voxelwise quadratic relationships between cerebrovascular reactivity from blood oxygen level-dependent imaging and the brain thermal response ( coefficient = 0.052, < .001; coefficient = 0.0068, < .001) and baseline brain temperatures ( coefficient = 0.59, = .008; coefficient = -0.13, < .001). A significant linear relationship was observed for the brain thermal response with cerebrovascular reactivity from arterial spin-labeling ( = .001). The findings support the presence of a brain thermal response exhibiting complex but significant interactions with tissue hemodynamics, which we posit to reflect a relative balance of heat-producing versus heat-dissipating tissue states. The brain thermal response is a potential noninvasive biomarker for cerebrovascular impairment.