Pyroelectric vidicon thermography and cold challenge quantify the severity of Raynaud's phenomenon

Thermographic images of the hands of patients with primary and secondary Raynaud's phenomenon and of a group of normal subjects, recorded before and after cold provocation using a pyroelectric vidicon thermal imaging system, showed differences in thermal distribution patterns that were characteristic of primary Raynaud's phenomenon (RP), scleroderma (RS) and normal, and were exaggerated by cold provocation. The responses to cold challenge, assessed by computing the mean temperature of the hand as it recovered from cold challenge and plotting these values against time to produce a rewarming curve, were also characteristic of the patient and the normal groups, and gave an indication of the severity of circulatory impairment. Methods are described for the simple numerical characterization of these parameters.