Abstract
Background SLE arthritis is difficult to evaluate because of the sometimes-evanescent nature of the symptoms and limitations of physical exams and imaging studies. Dynamic diffuse optical spectroscopy (dDOS) can be used to assess changes in light absorption through tissues during transient venous occlusion. The optical signal reflects changes in blood perfusion and has diagnostic value in rheumatoid arthritis. The current study explored the use of dDOS in SLE arthritis.
Methods 12 SLE patients (ACR criteria) with active arthritis and 5 controls were evaluated. A dDOS sensor module was developed (figure 1a). Hemodynamic effects were obtained by inflating a BP cuff to 40 mmHg ×60 s. Light at 3 wavelengths (lambda=530, 655, 940 nm) was used to illuminate joints at 8 different points. Transmitted light intensities were measured with Si-photodetectors at 8 other positions (total 8×8×3=192 signal traces). Swollen, tender and healthy joints were examined by the same assessor.
Results SLE patients and normal controls dDOS data were available for analysis from 66 and 24 proximal interphalangeal (PIP) joints, respectively (PIPs 2–4). Best results were obtained at 530 nm with cuff inflation at 40 mmHg. A representative measurement of 3 SLE arthritis and 3 normal joints is shown in figure 1b, highlighting differences in rise and plateau time. Given the pronounced effects at lambda=530 nm, we speculate that altered vessel physiology paired with already-increased blood pooling in the affected inflamed joints resulted in quicker increase in light absorption (rise time) that is maintained longer (plateau time) compared to normal joints. The AUC for dDOS was consistent with excellent discrimination, AUC=0.8639, sensitivity=76.19, specificity=88.57 (figure 1c).
Methods 12 SLE patients (ACR criteria) with active arthritis and 5 controls were evaluated. A dDOS sensor module was developed (figure 1a). Hemodynamic effects were obtained by inflating a BP cuff to 40 mmHg ×60 s. Light at 3 wavelengths (lambda=530, 655, 940 nm) was used to illuminate joints at 8 different points. Transmitted light intensities were measured with Si-photodetectors at 8 other positions (total 8×8×3=192 signal traces). Swollen, tender and healthy joints were examined by the same assessor.
Results SLE patients and normal controls dDOS data were available for analysis from 66 and 24 proximal interphalangeal (PIP) joints, respectively (PIPs 2–4). Best results were obtained at 530 nm with cuff inflation at 40 mmHg. A representative measurement of 3 SLE arthritis and 3 normal joints is shown in figure 1b, highlighting differences in rise and plateau time. Given the pronounced effects at lambda=530 nm, we speculate that altered vessel physiology paired with already-increased blood pooling in the affected inflamed joints resulted in quicker increase in light absorption (rise time) that is maintained longer (plateau time) compared to normal joints. The AUC for dDOS was consistent with excellent discrimination, AUC=0.8639, sensitivity=76.19, specificity=88.57 (figure 1c).
| Original language | English (US) |
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| DOIs | |
| State | Published - 2019 |