Feasibility of photoacoustic/ultrasound imaging of synovitis in finger joints using a point-of-care system

Abstract

We evaluate a portable ultrasound and photoacoustic imaging (PAI) system for the feasibility of a point-of-care assessment of clinically evident synovitis. Inflamed and non-inflamed proximal interphalangeal joints of 10 patients were examined and compared with joints from 7 healthy volunteers. PAI scans, ultrasound power Doppler (US-PD), and clinical examination were performed. We quantified the amount of photoacoustic (PA) signal using a region of interest (ROI) drawn over the hypertrophic joint space. PAI response was increased 4 to 10 fold when comparing inflamed with contralateral non-inflamed joints and with joints from healthy volunteers (p < 0.001 for both). US-PD and PAI were strongly correlated (Spearman’s ρ = 0.64, with 95% CI: 0.42, 0.79). Hence, PAI using a compact handheld probe is capable of detecting clinically evident synovitis. This motivates further investigation into the predictive value of PAI, including multispectral PAI, with other established modalities such as US-PD or MRI.

Novel Optical Techniques for Imaging Microcirculation in the Diabetic Foot

“…The feasibility of detection of synovitis in finger joints in rheumatoid arthritis patients with PAI was tested by Van den Berg et al [88] using a handheld ultrasound probe with integrated diode lasers (Figure 7). They used a portable system to examine inflamed and non-inflamed proximal interphalangeal joints of ten patients and compared these with joints from seven healthy subjects.…”

“…Generally, the costs for the equipment for each technique are tens of thousands of euros. Most PAI systems are quite expensive because of the laser, however, these costs can be reduced when a diode laser is used, as was for example applied in the study by van den Berg et al [88]. Furthermore, LDPI systems are more expensive than LSCI because the camera for LDPI needs to have a higher frame-rate to capture the LDPI data.…”

“…PAI systems are usually less compact and therefore less convenient to use in the clinical setting. This might be fixed with the current development of handheld PAI probes, as described in multiple studies [74,84,86,88,90], although the scanning surface and therefore the imaging dimensions are smaller in those devices. LDPI, LSCI and HSI are all available in compact systems and usable on portable trolleys for bedside measurements for the patient.…”

“…PAI device (handheld PAI probe), as used in the study of Van den Berg et al[88]. Source: Mennes, O.A., 2018.…”

Reducing artifacts in photoacoustic imaging by using multi-wavelength excitation and transducer displacement

“…PA images are reconstructed from the detected signals providing localized information about optical absorption properties of the samples. In clinical applications, the obtained information of endogenous chromophores such as hemoglobin helps diagnosing early stages of various diseases [2,[4][5][6]. A typical PAI system basically consists of a light source and US transducer array.…”