Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods

Abstract

Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion and supply the brain with the necessary oxygen and energy substrates. Adequate brain perfusion is required to support normal brain function, to achieve successful aging, and to navigate acute and chronic medical conditions. We review the general principles of CBF measurements and the current techniques to measure CBF based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance imaging, ultrasound techniques, thermal diffusion, and optical methods. We also review techniques for arterial blood pressure measurements as well as theoretical and experimental methods for the assessment of CA, including recent approaches based on optical techniques. The assessment of cerebral perfusion in the clinical practice is also presented. The comprehensive description of principles, methods, and clinical requirements of CBF and CA measurements highlights the potentially important role that noninvasive optical methods can play in the assessment of neurovascular health. In fact, optical techniques have the ability to provide a noninvasive, quantitative, and continuous monitor of CBF and autoregulation.

Molecular imaging with engineered physiology

“…Although quantification of probe responses might not be required for detecting the mere presence versus absence of analytes or probe-expressing cells, more quantitative readouts would be needed for absolute measurements of continuously varying molecular or cellular parameters, such as analyte concentrations, or for comparison of such variables across different subjects or treatments. In these cases, approximately quantitative responses would have to be inferred from in vitro probe measurements (EC 50 values and receptor affinities), in combination with haemodynamic modelling3738 and calibration techniques3940. In animals, it might also be possible to quantify vasoactive probe readouts with respect to standard curves obtained by injecting known concentrations of probes and analytes.…”

Evaluation of Enhanced Learning Techniques for Segmenting Ischaemic Stroke Lesions in Brain Magnetic Resonance Perfusion Images using a Convolutional Neural Network Scheme

“…One such parameter is cerebral perfusion, which describes the passage of blood through the brain’s vascular network. Amongst the several techniques used to measure cerebral perfusion (Fantini et al, 2016; Petrella and Provenzale, 2000), MRI is perhaps the most widely used due to its non-invasiveness. Thus, having great potential in becoming an important tool in the diagnosis and treatment of patients with cerebrovascular disease and other brain disorders.…”

β‐Blockade attenuates renal blood flow in experimental endotoxic shock by reducing perfusion pressure

“…Assessment and interpretation of renal autoregulation is not trivial (Cupples & Braam, ; Loutzenhiser, Griffin, Williamson, & Bidani, ). Studies have addressed either static or dynamic autoregulation: static refers to RPP and RBF values under steady‐state conditions that are observed over a time scale of minutes to hours, while dynamic refers to transient RPP and RBF changes that are observed in a time scale of seconds (Fantini, Sassaroli, Tgavalekos, & Kornbluth, ). Even though the mechanisms underlying static and dynamic renal autoregulation may overlap, lack of correlations between the two emphasizes the need to assess both (Jong, Tarumi, Liu, Zhang, & Claassen, ).…”