Correlation between the infrared thermogram and microvascular abnormalities of the nailfold in patients with systemic sclerosis

Abstract

Introduction Systemic sclerosis (SSc) is a multisystemic disease with an extensive microvasculopathy. The gold standard for its investigation is nailfold videocapillaroscopy (NVC). Aim To assess the value of thermography (IRT) for the assessment of microvasculopathy in patients with SSc. Material and methods Nineteen patients with limited cutaneous SSc were enrolled in the study. They underwent IRT imaging and NVC. An average temperature (Tavg) at the nailfold and a gradient of temperatures (ΔTavg) between the central metacarpus of the hand and the nailfold was determined for all fingers. NVC pictures were classified to capillaroscopic patterns according to Cutolo et al . system and they were analysed quantitatively to measure the density of capillaries and to calculate capillaroscopic skin ulcers risk index (CSURI) for each finger separately. Results There was only a moderate correlation (0.4 < r < 0.6) between thermographic parameters and density of capillaries in fingers II–V ( r = 0.5; p < 0.001 for Tavg and r = –0.45; p < 0.001 for ΔTavg), but none in thumbs ( r = 0.29; p = 0.089 for Tavg and r = –0.19; p = 0.275 for ΔTavg). Early pattern was associated with a significantly greater surface temperature (Tavg) of nailfolds and essentially milder ΔTavg in fingers II–V when compared to all other capillaroscopic patterns in fingers II–V. Surface temperature (Tavg) was significantly lower and ΔTavg was markedly more pronounced in fingers II–V with a greater risk of development of digital ulcers (DU) calculated by CSURI. Conclusions Although IRT measurements correlate only moderately with density of capillaries, this technique seems to be substantial to determine the capillaroscopic pattern and to identify patients at greater risk of DU development.

Imaging techniques for assessment of vascular involvement in systemic sclerosis

“…A local cold challenge does not account for the influence of convective and conductive heat exchange on surface skin temperature, thus does not truly recapitulate RP [32]. Although IRT measurements correlate only moderately with density of capillaries, abnormal initial thermography associates with nailfold capillaroscopy patterns and identifies SSc that are more likely to develop digital ulcers and require more frequent surgical debridement [33,34]. Of interest, baseline thermographic temperature is influenced by gender but, not race and trends show decreased perfusion in tobacco users relative to nonsmokers, which highlights the importance of subject characterization [35].…”

Diagnostic Methods for Microvasculopathy in Systemic Sclerosis

“…The measure of temperature in nailfolds of thumbs seems to be preferentially performed in the fist, when thumbs lay on a cork plate or gauze and fingers II-V remain covered below (Figure 14). Regions of interests can be determined over the nailfolds, but measurements may include a gradient of temperatures between the center of the metacarpus and the nailfolds of separate fingers [32,33].…”

“…Although there was found only moderate correlation between temperature measurements in nailfolds and the density of capillaries, thermography showed dependence of IR emission on capillaroscopic patterns in patients with SSc. One should remember that thermography measures IR emission from the portion of the tissue (3D space), whereas capillaroscopy quantifies density of vascular loops on a short distance (2D space) [32]. Thermography recently demonstrated differences in the control of temperature in hands between SSc patients with limited and diffuse cutaneous involvement [33].…”

“…Thermography recently demonstrated differences in the control of temperature in hands between SSc patients with limited and diffuse cutaneous involvement [33]. Finally, thermography seems to be promising for the identification of fingers at then greater risk for the development of digital tip ulcers [32].…”

Correlation between Microvascular Damage and Internal Organ Involvement in Scleroderma: Focus on Lung Damage and Endothelial Dysfunction

“…Moreover, it can be combined with a local cold challenge: exposure to a localized cold stimulus largely mimics an RP attack, thus allowing dynamic vascular assessment [89]. The pathological findings of IRT have been shown to be predictive of an increased likelihood of developing DU and a more frequent need for surgical debridement [54,90], however, there is still no standardization [91].…”