Photoacoustic 3D imaging can detect potential microvascular injuries

The photoacoustic imaging (PAI) system is an emerging imaging modality that can be useful in clinical diagnostic testing. Previous studies have shown utility of PAI in diagnosing breast cancer, visualizing vascular change in ageing, and planning flap reconstruction surgeries. In this study, we show that PAI can be used to non-invasively visualize microvascular injuries in smokers, and in a vasculitis patient. We used two prototype PAI systems, PAI-03, and PAI-04 in this study. These systems were equipped with hemisphere-detector arrays, and used lasers at wavelengths of 795 nm (PAI-03), 756 and 797nm (PAI-04). Healthy volunteers and a patient diagnosed with vasculitis were enrolled upon obtaining written informed consent. The whole hand of the volunteers was scanned. We noted there were unique circular structures that we coined "minute signals". There were higher number of minute signals in smokers than in non-smokers. Enhanced minute signals were noted in the patient with vasculitis. In this patient, minute signals were suggested to have lower oxygenated hemoglobin content, likely suggesting blood clots or hemorrhage. Our study shows PAI systems can visualize unappreciated abnormalities in fine vasculatures non-invasively. Use of PAI can extend to other clinical entities with suspected vascular involvement.