Localized real time blood flow measurements.

A novel method for real time, localized, flow measurements is applied to blood flow in human fingers. Results for arterial and venous flow in normal subjects and patients with abnormal blood circulation are presented. Effects of blood flow regulation by the autonomic nervous system have been observed. Stricture of the digital arteries could be clearly demonstrated in a patient with Raynaud's phenomenon. Experimental signals due to pulsatile flow in a model system can be simulated in a quantitative way. The calibration, however, depends on the actual spin-spin relaxation time and the shape of the pulsatile flow vs. time curve. Due to these limitations, the volume flow rate can be measured with a relative error of approximately +/- 25%.