Apparatus for measuring cerebral blood flow in a patient undergoing coronary artery bypass grafting at Duke University, Durham, North Carolina. There are bilateral detectors of ¹³³Xe and a jugular bulb catheter for sampling of jugular blood used to compute cerebral metabolism. This technique was routinely used in the many studies at Duke, but a simpler single detector and no jugular bulb catheter were used in the classic paper.¹