Transcranial Imaging of Functional Cerebral Hemodynamic Changes in Single Blood Vessels using in vivo Photoacoustic Microscopy

• Published in: Journal of cerebral blood flow and metabolism Vol. 32; no. 6; pp. 938 - 951
• Main Authors: Liao, Lun-De, Lin, Chin-Teng, Shih, Yen-Yu I, Duong, Timothy Q, Lai, Hsin-Yi, Wang, Po-Hsun, Wu, Robby, Tsang, Siny, Chang, Jyh-Yeong, Li, Meng-Lin, Chen, You-Yin
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.06.2012; Nature Publishing Group; Sage Publications Ltd
• Subjects: Animals; Arteries; Arterioles; Biological and medical sciences; Blood vessels; Brain; Cerebral Arteries - physiology; Cerebral blood flow; Cerebrovascular Circulation - physiology; Cortex; Electrical stimuli; Hemodynamics; Hemodynamics - physiology; Hemoglobin; Hemoglobins - metabolism; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Mice; Microscopy; Nervous system; Neuroimaging; Neurology; Oxygen; Oxygen - metabolism; Photoacoustic Techniques - instrumentation; Photoacoustic Techniques - methods; Photoacoustics; Probes; Skull; spatial discrimination; superior sagittal sinus; Ultrasonic investigative techniques; Vascular diseases and vascular malformations of the nervous system; Veins; transcranial photoacoustic microscopy; hemodynamic response; hemoglobin oxygen saturation; cerebral blood volume; forepaw electrical stimulation; total hemoglobin concentration; Optoacoustical microscopy; Oxygen; Nervous system diseases; Saturation; Cerebral disorder; Encephalon; Blood volume; Central nervous system disease; Hemoglobin; Hemodynamics; Cerebrovascular disease; Functional imaging
• DOI: 10.1038/jcbfm.2012.42
• ISSN: 0271-678X; 1559-7016

Optical imaging of changes in total hemoglobin concentration (HbT), cerebral blood volume (CBV), and hemoglobin oxygen saturation (SO2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36 × 65-μm2 spatial resolution. In addition, an early decrease of SO2 in single blood vessels during activation (i.e., ‘the initial dip’) was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels.