Connective tissue diseases affect finger-vein patterns, pointing to these patterns as a possible biometric authentication technique and diagnostic tool in rheumatoid arthritis (RA). These are the conclusions of a study, “Personal Authentication Analysis Using Finger-Vein Patterns in Patients with Connective Tissue Diseases—Possible Association with Vascular Disease and Seasonal Change,” published in the journal PLOS ONE.
Personal identification relies increasingly on biometric authentication techniques, such as fingerprint authentication, iris recognition, and face recognition. Finger-vein patterns, acquired by near-infrared (IR) light, were first developed 20 years ago in Japan, and have since been improved and established by the Hitachi Central Research Laboratory. This technique relies on light transmission through tissues, a factor also affected by the absorbance of tissue proteins such as hemoglobin. Because the feasibility of this technique had only been studied in healthy studies, researchers wanted to investigate how it might be affected by diseases that impact blood flow in peripheral tissues, such as is seen in connective tissue diseases.
The team acquired finger-vein pattern images of 68 patients with connective tissue diseases and 24 healthy subjects. These images were acquired by transmitting near-infrared light through the fingers and captured as CCD (charge-coupled device) images. The results, acquired once in each season for one year, were compared with those of healthy volunteers to detect possible differentiating characteristics and/or problems using this identification method in people with diseases ranging from RA and lupus to mixed connective tissue disease (MCTD) and systemic sclerosis (SSc).
The results showed that the authentication of patients was more sensitive to seasonal change than for healthy volunteers. In the winter, patients’ C values, a measure of change in blood circulation, showed statistically significant reduction not only compared to healthy controls but also compared to patients’ C values in other seasons. Healthy controls showed no significant seasonal variation. The values were especially reduced in November and February for patients with systemic sclerosis or mixed connective tissue disease, while patients with rheumatoid arthritis did not show statistically significant seasonal changes. Researchers attribute these observations to the fact that SSc patients experience reduction of blood flow, dermal sclerosis, and skin roughness, which affect the vein pattern imaging.
The team concluded this method can be used in most patients with connective tissue diseases and has a diagnostic value to determine connective tissue disease throughout the year — provided special attention is given to patients with advanced disease such as SSc. “Although this method may not contribute to the precision of classification of connective tissue diseases, it has a possibility to assist evaluation of the severity of impairment in peripheral circulation noninvasively,” the authors wrote.