“…There, the CBF value includes increased nonfunctional shunt blood flow in the brain surface venous network during retrograde perfusion [17]. Laser flowmetry provides continuous monitoring that enables probe positioning to exclude nonfunctioning shunt flow in the large veins [16,17]. The microsphere method [13, 21,24] shows the distribution and the functional quantity of nutrient blood flow through the capillary bed in the brain when an adequate size is selected.…”