Sergio Fantini: Optical assessment of cerebral autoregulation

Cerebral autoregulation (CA) is a homeostatic mechanism that maintains a relatively constant cerebral blood flow (CBF) in the presence of changes in the cerebral perfusion pressure (CCP), defined as the difference between mean arterial pressure (MAP) and intracranial pressure (ICP).

Given the importance of adequate and consistent brain perfusion, CA is critical for brain viability and is known to be impaired in a number of neurological disorders. Global brain measurements of dynamic CA have been performed with transcranial Doppler ultrasound (to sense the blood flow velocity in the middle cerebral artery) and finger plethysmography (to measure systemic MAP as a surrogate for CCP).

Optical methods offer the advantage of providing local measurements of cerebral blood flow and CA, thus allowing for local assessment and spatial mapping of CA. Optical techniques for the non-invasive assessment of CA include near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS).

In this plenary session, Segio Fantini of Tuft's University describes his lab's approach to CA assessment with NIRS, complemented by the novel technique of coherent hemodynamics spectroscopy (CHS), and our findings of the expected enhancement in CA during hyperventilation-induced hypocapnia. He also reports dynamic traces of local CBF measured with NIRS-CHS and DCS during transient changes in MAP. Optical techniques offer the potential to address the challenge of continuous monitoring of local cerebral autoregulation at the bedside and in a critical care environment.

Sergio Fantini received his PhD in physics from the University of Florence, Italy, in 1992. His dissertation was based on a Raman scattering study of ceramic superconductors. From 1993 to 1999, he held postdoctoral and faculty appointments at the University of Illinois at Urbana-Champaign, Department of Physics. In 1999, he joined Tufts University as an Assistant Professor, and has been one of the inaugural faculty members of the Department of Biomedical Engineering, created at Tufts in 2002.

Fantini's research interests are in the area of biomedical optics, specifically in diffuse near-infrared spectroscopy and imaging of biological tissues. His research laboratory has ongoing projects aimed at non-invasive functional imaging of the brain, the study of cerebral and skeletal muscle hemodynamics, and the development of novel instrumentation for optical mammography. Fantini's research has resulted in eleven patents and about two-hundred journal and conference proceedings publications.