High speed solution of 2nd order curves with special application to planar sections of blood vessels

Rapid determination of the areas of planar sections through a blood vessel are required in an on-line blood flow measurement system which utilizes an intravascular ultrasonic catheter. Vessel areas are determined by: (1) using a fast algorithm to fit an ellipse to 6 data points of the vessel wall's location measured with the ultrasonic catheter; (2) computing the area of the determined ellipse. The program is implemented in a general purpose computer with a hardware floating point processor, using 3320 of 16 bit words of memory for storing variables, data, look-up tables, and computation instructions. The program executes in 3 ms, which, when combined with the other computations and timing requirements of the system, allows instantaneous flow computation every 7.3 ms. The system is fast enough to follow pulsatile blood flow. The algorithm applies in other areas which also require fast quantitative measurement; for example, in determining organ or tissue structural contours describable with a 2nd order equation.