Influence of Ambient Temperature on Recording of Skin and Deep Tissue Temperature in Region of Lumbar Spine

Medical Microwave Radiometry (MWR) allows non-invasive measurement of human internal body temperature which is potentially useful for diagnosing a range of pathologies. The technique is used to to meaure so-called brightness temperature and it is recommended that investigations are performed in a room with temperature controlled in the range 20 to 24°C. This is not always possible in impromptu investigations or if studies are to be conducted in certain remote facilities or outdoors. We have therefore investigated the influnce of room temperature on brightness temperature (BT) and skin temperature (ST) measurements were obtained using the respective microwave and infra red sensors of the MMWR2020 (former RTM-01-RES) system (www.mmwr.co.uk). MWR measurements of BT and ST were obtained for 93 healthy subjects in the sitting position. Recordings were taken above each of the L1 to L5 vertebral bodies and along corresponding left and right paravertebral lines. The data were subdivided according to whether room temperature was recorded as being from 17.1 to 21.9°С (n=24) (i.e. low temperature), 22.0 to 26.9°С (n =56) (i.e. moderate temperature) or 27.0 to 29.5°C (n=13) (i.e. high temperature). The average value of BT was identical at low and moderate temperatures. No correlation is observed between BT and room temerature. On the other hand average value of ST is linearly proportional to rise in room temperature (R2 = 0.36). In conclusion, the present study has shown that reliable values of BT, but not ST, can be obtained even when room temperature can vary between 17 and 30°C. However, to ensure patient comfort and to support simultaneous measurement of ST, MWR study of the lumbar region should be conducted with room temperature controlled to lie between 22 and 26°C.