Repeatability of high‐resolution laser Doppler images of the hands in patients with systemic sclerosis and secondary Raynaud's phenomenon

OBJECTIVES The objective of the study was to establish the repeatability of baseline diagnostic images of the dorsum of the hands acquired using a high resolution Laser Doppler imager in patients with Raynaud's phenomenon secondary to Systemic Sclerosis (SSc). METHODS The dorsal side of the hands of 22 patients (8 male 14 female) , age range 29-73, median 62, with SSc and secondary Raynaud's phenomenon were imaged over two consecutive days at approximately the same time using a Moor Instruments High Resolution Laser Doppler imaging unit. The images were analysed by taking regions of interest at discrete locations in the images to calculate dimensionless values of flux(PU). Repeatability of the diagnostic investigation was assessed by using methods described by Bland and Altman and by also plotting the results from visit 1 against visit 2 and calculating the line of best fit. RESULTS AND CONCLUSIONS Based on the criteria that 95% of all measurement differences should be within a factor of 1.96 of the standard deviations of the mean values, then high resolution Laser Doppler Imaging technique is probably repeatable when acquiring and analysing baseline images of patients with Raynaud's phenomenon secondary to SSc. However a larger study with more patients is required to prove this conclusively - as only data from 19 patients was analysed [3 patients were not included due to technical issues] - and was therefore susceptible to marked clinical variations in patients presenting on different days for the investigations.