Application of Photoacoustic Methods and Confocal Microscopy for Monitoring of Therapeutic Response in Plaque Psoriasis

Abstract

Psoriasis is prone to relapses and requires long-term therapy that may induce a range of adverse effects; therefore, an efficient and early detection of relapses is desirable. In this study, photoacoustic imaging and confocal laser scanning microscopic (CLSM) methods were investigated for their suitability in psoriasis follow-up examinations. Using a high-resolution photoacoustic system, the vascular structures of 11 psoriatic patients and 6 healthy volunteers were investigated. No differences were detected with respect to the average vessel diameter and vasculature per unit volume in the tissue of healthy volunteers and non-lesional and lesional skin areas of psoriatic patients. By means of CLSM, the diameters of the dermal papillae of 6 volunteers and 6 psoriatic patients were determined. The diameters of the dermal papillae of the healthy volunteers (0.074 ± 0.006 mm) revealed no significant difference when compared to non-lesional skin areas of psoriatic patients (0.079 ± 0.005 mm). The results obtained for the lesions in psoriatic patients showed a significant difference (Wilcoxon test, p = 0.028) between the diameters of the dermal papillae of the lesional skin areas (0.114 ± 0.012 mm) and the non-lesional skin areas (0.079 ± 0.005 mm). Thus, CLSM can be applied for monitoring psoriasis follow-up examinations.

Progress in the application of reflectance confocal microscopy in dermatology

“…The lesions of psoriasis can occur anywhere in the body, usually symmetrically distributed [ 28 ] ( Figure 1 J ). The characteristics under RCM include hyperkeratosis, parakeratosis, thickening of the spinous layer, accumulation of cells with a lobular nucleus and expansion of the dermal papilla in dilated vessels [ 29 , 30 ] ( Figure 1 K ). The histopathological features of psoriasis are as follows: hyperkeratosis, parakeratosis, thickening of the spinous layer, capillary dilatation and hyperaemia, and peripheral inflammatory cell infiltration [ 31 , 32 ] ( Figure 1 L ).…”

Optoacoustic imaging of the skin

“…Other microscopic OA imaging systems have further demonstrated a powerful performance for the characterization of psoriasis. 113,114 Inflammation-related alterations to the dermal vasculature are similarly present in Eczema with dilation and increased vessel density clearly observed in the OA images, although the capillary loops appear to be sparser and more irregularly distributed than in psoriasis. 111…”

Slide Over

“…94 Because a scanningbased imaging setup is used in PAM, the functionality of confocal fluorescence microscopy can be easily integrated into a PAM system. 95 The integration of PAM with other scanning-based imaging modalities such as Fourier-domain optical coherence tomography has also been reported. 94…”