Novel use of laser Doppler imaging for investigating epicondylitis.

Abstract

This investigation evaluated a novel form of tissue perfusion measurement, laser Doppler imaging (LDI), in a case of lateral epicondylitis to establish if it might have applications in assessing soft tissue lesions. LDI was used in conjunction with ultrasonography to provide information about tissue oedema as well as the power Doppler signal as an alternative method of assessing blood flow. A laser Doppler imager with a near-infrared (NIR) laser source was used to improve tissue penetration and yield measurements of perfusion (flux) from structures under the skin. Skin temperature over the lateral epicondylar region was also measured. Ultrasonography was used in both grey-scale and power Doppler modes. LDI, temperature measurements and ultrasonographic data were obtained before treatment and serially after local injection of methylprednisolone. Before treatment there was increased perfusion and skin temperature and the presence of a power Doppler sign associated with the right lateral epicondyle as well as oedema at the extensor origin. None of these was present at the asymptomatic contralateral epicondylar region. Twenty-four hours after methylprednisolone administration, both perfusion and skin temperature had increased, and they declined over the subsequent 48 h. Although skin temperature had declined to normal (referenced to the contralateral epicondyle) by the third day after injection, it took until the eleventh day after injection for perfusion to normalize. LDI using an NIR laser source appears to be an effective non-invasive method for the examination of inflammatory responses in soft tissue, with greater sensitivity than thermally based methods. In addition, LDI was found to correlate with power Doppler ultrasonography.