TEMPERATURE-DEPENDENT ULTRASOUND COLOR FLOW DOPPLER IMAGING IN THE STUDY OF A VX2 TUMOR IN RABBITS - PRELIMINARY FINDINGS

Neovascularity in a VX2 carcinoma in rabbit liver was detectable, usin g an ultrasonic color Doppler flow imager. Intraportal infusion of hea ted saline increased the fractional area of color flow Doppler signals by at least 5% and as much as 30%, within and surrounding the tumors of all six rabbits studied. The effect of the fluid load was an increa se in fractional area of color flow Doppler signals by 5 to 20% and wa s determined by the measurements following infusion and return to base line temperature. The largest increment in color Doppler signal was ob served in peritumoral vessels (10-40%). In contrast, the fractional ar ea of color-coded pixels within the tumor was only slightly higher or lower (5-10%) at the peak temperature than at the baseline measurement s. The temperature within the tumors was as much as 1 degree lower tha n parenchymal tissue in all animals measured. This was presumably due to the portal vein blood supply to normal tissue and predominantly hep atic artery supply to the pathological tissue. High velocities and per sistent bidirectional flow were observed within the tumors only at the peak temperatures (>43.5-degrees-C). This experiment suggests that th ermal stress may enhance tumor detectability by color Doppler imaging. Further development of a quantitative analysis method for color Doppl er studies is needed.