P164 Can non-invasive techniques be used to image calcinosis?

Abstract

Abstract Background A significant proportion of patients with systemic sclerosis (SSc, 20-40%) will develop subcutaneous calcinotic deposits which are painful and can perforate the skin, causing ulceration. The underlying aetiology is unknown and there is currently no effective treatment. Diagnosis is often made with plain radiography, which is not ideal for long-term monitoring. Identifying non-invasive techniques which do not involve ionising radiation will improve our understanding of calcinosis and how to monitor this over time, facilitating the development of potential treatments. The aim of this study was to assess several non-invasive imaging techniques to measure oxygenation (multispectral imaging), perfusion (thermography [a pseudo measure of perfusion] and laser speckle imaging) and size and depth (high frequency ultrasound) of the calcinoses. The hypothesis of the study was that there would be relationships between oxygenation, perfusion and calcinosis size and depth. Methods Twenty-one patients with SSc (all female, median age 63 (IQR 55 to 70) years; disease duration since onset of first non-Raynaud’s feature 14 (9 to 23) years, Raynaud’s phenomenon duration 23 (12- 36) years; underwent imaging of calcinosis. Measurements of oxygenation, perfusion and vessel size and depth were performed at the site of calcinosis and adjacent skin. Results There was no difference in oxygenation at the site of calcinosis vs adjacent median 0.15 (IQR 0.07 to 0.22) vs. 0.16 (0.00 to 0.21) arbitrary units respectively; non-significant. There was a trend for skin temperature (perfusion) to be lower at the site of the calcinosis compared to the adjacent area (calcinosis, 31.4 (28.4 to 35.6) vs adjacent 32.8 (28.4 to 35.7) oC; p = 0.052. Perfusion as measured by speckle imaging was significantly reduced 107.3 [60.3 to 213.4] vs 312.1 [107.8 to 432.2] arbitrary perfusion units; p < 0.01. The mean depth of the calcinoses was 1.5 (1.11 to 2.07) cm and mean lesion area was 3.06 (2.33 to 4.62) cm2. No relationships were identified between perfusion, oxygenation or calcinosis depth and area. Conclusion Perfusion is reduced at the calcinotic sites, as measured by laser speckle imaging and also (although not significantly) as measured indirectly by thermography. That perfusion was decreased in the area of the calcinosis versus the adjacent skin may be due to the pressure on the skin leading to ischaemia, or it may be that calcinosis develops in areas which are under-perfused. This study has demonstrated the feasibility of imaging calcinosis properties. The ability to measure the depth and subcutaneous area with high frequency ultrasound may provide a useful outcome measure of treatment efficacy. Disclosures T.L. Moore None. E. Marjanovic None. J.B. Manning None. G. Dinsdale None. S. Wilkinson None. M.R. Dickinson None. A.L. Herrick None. A.K. Murray None.