Potential Use of Optical Coherence Tomography and High-Frequency Ultrasound for the Assessment of Nail Disease in Psoriasis and Psoriatic Arthritis

Psoriatic nail disease is increasingly recognised to be of major clinical and research relevance. Clinical assessment remains the current gold standard for its evaluation.We compared optical coherence tomography (OCT) and ultrasound (US) for nail disease assessment in psoriatic disease.18 patients with at least one involved nail and 12 healthy controls were scanned using OCT; psoriatic patients also had an US scan (using a linear probe at 9-14 MHz). Nail and contour abnormalities were documented. Clinical onychopathy was scored independently using the modified Nail Psoriasis Severity Index.Among 180 nails, 67.8% had clinical findings whereas 33.9% were abnormal by US and 44.4% had abnormalities on OCT. A positive OCT had a sensitivity and specificity of 44.4 and 95.8%, respectively, with a positive likelihood ratio of 10.7 for nail disease. OCT demonstrated 76.3% absolute agreement compared with clinical assessment and 65% with US. OCT detected subtle abnormalities in 12 clinically normal nails and in 41 nails with normal US findings.These findings show that OCT has a potential for the systematic characterisation of psoriatic nail changes and could be useful in diagnosis and more objective assessment of treatment response.