Computerized Nailfold Video Capillaroscopy — A New Tool for Assessment of Raynaud's Phenomenon

MARINA E. ANDERSON, P. DANNY ALLEN, TONIA MOORE, VAL HILLIER, CHRISTOPHER J. TAYLOR, and ARIANE L. HERRICK

ABSTRACT.

Objective. To develop a computer based nailfold video capillaroscopy system with enhanced image quality and to assess its disease-subgroup resolving power in patients with primary and secondary Raynaud's phenomenon (RP).

Methods. Using frame registration software, digitized video images from the microscope were combined to form a panoramic mosaic of the nailfold. Capillary dimensions (apex, arterial, venous, and total width) and density were measured onscreen. Significantly, the new system could guarantee analysis of the same set of capillaries by 2 observers. Forty-eight healthy control subjects, 21 patients with primary RP, 40 patients with limited cutaneous systemic sclerosis (lcSSc), and 11 patients with diffuse cutaneous SSc (dcSSc) were studied. Intra- and interobserver variability were calculated in a subset of 30 subjects.

Results. The number of loops/mm was significantly lower, and all 4 capillary dimensions significantly greater, in SSc patients versus controls plus primary RP patients (p < 0.001 for all measures). When comparing control (+ primary RP) patients with SSc patients (lcSSc + dcSSc) the most powerful discriminator was found to be the number of loops/mm. Results for intra- and interobserver reproducibility showed that the limits of agreement were closer when both observers measured the same capillaries.

Conclusion. The key feature of the newly developed system is that it improves reproducibility of nailfold capillary measurements by allowing reidentification of the same capillaries by different observers. By allowing access to previous measurements, the new system should improve reliability in longitudinal studies, and therefore has the potential of being a valuable outcome measure of microvessel disease/involvement in clinical trials of scleroderma spectrum disorders. (J Rheumatol 2005;32:841-8)

Key Indexing Terms:

NAILFOLD VIDEO CAPILLAROSCOPY
NAILFOLD MICROSCOPY
OUTCOME MEASUREMENT
MICROVASCULAR
RAYNAUD'S PHENOMENON
SYSTEMIC SCLEROSIS

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From the University of Manchester Rheumatic Diseases Centre, Hope Hospital, Salford; and Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK.

Supported by a project grant from the Raynaud's and Scleroderma Association. Dr. M.E. Anderson was funded by the Arthritis Research Campaign.

M.E. Anderson, MRCP, Clinical Research Fellow; T. Moore, BSc, Vascular Technician; A.L. Herrick, MD, Senior Lecturer in Rheumatology, University of Manchester Rheumatic Diseases Centre; P.D. Allen, PhD, Research Associate; V. Hillier, PhD, Senior Lecturer in Statistics; C.J. Taylor, PhD, Professor of Imaging Science, Imaging Science and Biomedical Engineering, University of Manchester.

Address reprint requests to Dr. A.L. Herrick, Rheumatic Diseases Centre, Clinical Sciences Building, Hope Hospital, Eccles Old Road, Salford, M6 8HD, England. E-mail: aherrick@fs1.ho.man.ac.uk

Accepted for publication December 22, 2004.

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