The sonographic resistivity index: a non‐invasive parameter for therapeutic efficacy assessment in psoriatic onychopathy.

Psoriatic onychopathy represents a disabling manifestation of psoriasis, significantly affecting patients' life quality, as many therapies prove ineffective, limiting adherence.1 In patients with nail psoriasis, a thickening of the vessel wall as well as endothelial swelling is described, mainly because of deposition of immune complexes.2,3 These microcirculatory aspects can be quantified by the ultrasonographic resistivity index (RI), evaluating the resistance to blood flow by assessing systolic and diastolic peak flows of small nail bed vessels.4 RI depends on the inflammatory status: values around 0 show decreased tissue resistivity (no resistance to blood flow), while higher values showed an increased inflammation (maximum resistance to blood flow). Furthermore, we only assessed the RI at the level of the index finger of the dominant hand; further studies assessing RI in all involved fingernails and comparing the mean RI before/after therapy could provide more significant data regarding RI variation under therapy. Our patients presented a mean NAPSI score of 37.94 ± 7.91 and had a mean nail involvement of four nails.7,8 Furthermore, all patients had PASI score > 10, no signs of psoriatic arthritis, and were eligible for biological treatment. [Extracted from the article]

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