Blood Velocity and Volumetric Flow Rate Calculated from Dynamic 4D CT Angiography using a Time of Flight Approach

Purpose: A time of flight approach to the analysis of 4D CT angiography is examined to calculate blood flow in arteries. Materials and Methods: Software was written to track contrast bolus TOF along a central vessel axis. Time density curves were analyzed to determine bolus time to peak at successive vessel cross-sections which were plotted against vessel path length. A line of best fit was plotted through the resulting data and 1/slope provided a measurement of velocity. Results: Validation was successful in simulation and in flow phantoms, though quality of results depended strongly on quality of curve fit. In phantoms and in vivo, accuracy and reproducibility of measurements improved with longer path lengths and, in vivo, depended on the avoidance of venous contamination. Conclusions: Quantitative functional intravascular information such as blood velocity and flow rate may be calculated from 4D CT angiography.