Development of a Noninvasive Perfusion Measurement System

Aims of Consultant

1. Develop a non-invasive thermal perfusion measurement system
2. Evaluate and assess the perfusion system performance

Results of Consultant

Each of the aims was fully satisfied. We constructed a prototype of the thermal perfusion system using convective air cooling to provide the thermal event. Future directions involve designs using thermoelectric cooling and a totally passive probe, both of which have undergone successful initial testing. We have developed and built a tissue phantom test bed to evaluate the devices. The volumetric flow rate into the phantom tissue can be adjusted and quantified relative to perfusion through independent measurements and analysis. Sensitivity and repeatability were determined with flow rates from 0 to 30 cc/min, corresponding to perfusion rates from 0 to 0.09 ml/ml/s. Perfusion estimates provided a sensitivity of at least 0.005 ml/ml/s and an average repeatability of seven percent for flows greater than 5 cc/min. These experiments were further verified theoretically using a detailed finite element analysis to simulate flow conditions and the response to the imposed thermal event. Resulting perfusion estimates from these simulations were within ten percent of experimental estimates over this range. We have also conducted preliminary animal tissue experiments using rat kidney and rat liver models. These results clearly illustrated the ability of the probe to track changes in perfusion in animal tissue. Details of the probe design, the tissue phantom test bed design and results, and the preliminary studies are outlined in the following PDF file.

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