Feasibility of using thermal response to Ka band millimeter wave heating to assess skin blood flow

摘要

Objective: Implementation of clinical guidelines for diagnosing peripheral artery disease will demand screening many millions of patients who are considered at-risk. This will require faster, easier screening technologies to identify patients with compromised blood flow to the extremities. Approach: The feasibility of using surface temperature response to Ka band (26.5–40 GHz) nearfield irradiation to assess skin blood flow was explored using an animal model. Ears of domestic rabbits were subjected to low-power continuous wave radio frequency heating from an open-ended waveguide (WR-28) at f = 35 GHz. Three flow conditions were evaluated: (1) a baseline flow condition, (2) occluded flow and (3) reactive hyperemia. Surface temperatures were monitored continuously by means of an infrared thermography camera during each 2 min exposure. Main results: Ensemble average results showed significant differences (p < .05) at exposure times 30, 60, 90 and 120 s between baseline and occluded conditions, and between baseline and reactive hyperemia conditions. The occluded condition (N = 12) resulted in an average temperature increase of 21.4 °C ± 3.9 after 2 min, compared with an average increase of 12.1 °C ± 1.6 for baseline conditions (N = 9) and 4.7 °C ± 3.6 for post-occlusion/hyperemic conditions (N = 8). Significance: Results are compared with the results of a simple two parameter mathematical model. These results suggest a method for non-invasive skin blood flow assessment to screen for peripheral artery disease and associated risk of cardiovascular events.