Microwave Radiometry for the Diagnosis and Monitoring of Inflammatory Arthritis

Abstract

The ability of microwave radiometry (MWR) to detect with high accuracy in-depth temperature changes in human tissues is under investigation in various medical fields. The need for non-invasive, easily accessible imaging biomarkers for the diagnosis and monitoring of inflammatory arthritis provides the background for this application in order to detect the local temperature increase due to the inflammatory process by placing the appropriate MWR sensor on the skin over the joint. Indeed, a number of studies reviewed herein have reported interesting results, suggesting that MWR is useful for the differential diagnosis of arthritis as well as for the assessment of clinical and subclinical inflammation at the individual large or small joint level and the patient level. MWR showed higher agreement with musculoskeletal ultrasound, used as a reference, than with clinical examination in rheumatoid arthritis (RA), while it also appeared useful for the assessment of back pain and sacroiliitis. Further studies with a larger number of patients are warranted to confirm these findings, taking into account the current limitations of the available MWR devices. This may lead to the production of easily accessible and inexpensive MWR devices that will provide a powerful impetus for personalized medicine.

Keywords: imaging biomarker; microwave radiometry; osteoarthritis; rheumatoid arthritis; sacroiliitis; synovitis; ultrasound.

Figure 1

The measured temperature is the average temperature within the volume in the vicinity of the antenna, weighted according to its sensitivity pattern (lobe). The temperature of the dark (red) area volume is of more weight in the measurement than that of the volume in the light (yellow) area. Modified from Zampeli et al. [13].