Comparison between low cost USB nailfold capillaroscopy and videocapillaroscopy: a pilot study

Area of Science:

• Rheumatology
• Medical Imaging
• Dermatology

Background:

• Systemic sclerosis (SSc) diagnosis can be challenging, requiring specialized tools for microvascular assessment.
• Nailfold capillaroscopy is crucial for evaluating microvascular changes in SSc.
• Existing videocapillaroscopy methods can be costly and less accessible.

Purpose of the Study:

• To evaluate the feasibility of using Universal Serial Bus (USB) microscopy for nailfold capillaroscopy.
• To compare the diagnostic performance of USB microscopy with standard videocapillaroscopy in SSc patients.
• To assess the potential of USB microscopy as a low-cost, accessible diagnostic tool.

Main Methods:

• Acquired nailfold capillaroscopy images from 20 SSc patients and 20 healthy controls using both USB microscopy and videocapillaroscopy.
• Utilized custom software for automated analysis of capillary structure, including width and density.
• Employed receiver operating characteristic (ROC) curve analysis (Area Under the Curve - AZ) to compare diagnostic discrimination between groups.

Main Results:

• High-quality images were generated by the USB microscope, comparable to videocapillaroscopy.
• USB microscopy achieved an AZ of 0.81 for group separation based on mean capillary width, identical to videocapillaroscopy (AZ=0.81).
• Capillary density analysis showed a lower discrimination for USB microscopy (AZ=0.48) compared to videocapillaroscopy (AZ=0.70).

Conclusions:

• USB capillaroscopy demonstrates comparable diagnostic performance to videocapillaroscopy for discriminating SSc patients from controls based on capillary width.
• The high-quality imaging and diagnostic capability highlight USB microscopy's potential as an affordable and accessible tool for clinical and research settings.
• Further research may explore optimizing USB microscopy for capillary density assessment in SSc.