Visualising peripheral arterioles and venules through high-resolution and large-area photoacoustic imaging

Abstract

Photoacoustic (PA) imaging (PAI) has been shown to be a promising tool for non-invasive blood vessel imaging. A PAI system comprising a hemispherical detector array (HDA) has been reported previously as a method providing high morphological reproducibility. However, further improvements in diagnostic capability will require improving the image quality of PAI and fusing functional and morphological imaging. Our newly developed PAI system prototype not only enhances the PA image resolution but also acquires ultrasonic (US) B-mode images at continuous positions in the same coordinate axes. In addition, the pulse-to-pulse alternating laser irradiation shortens the measurement time difference between two wavelengths. We scanned extremities and breasts in an imaging region 140 mm in diameter and obtained 3D-PA images of fine blood vessels, including arterioles and venules. We could estimate whether a vessel was an artery or a vein by using the S-factor obtained from the PA images at two wavelengths, which corresponds approximately to the haemoglobin oxygen saturation. Furthermore, we observed tumour-related blood vessels around breast tumours with unprecedented resolution. In the future, clinical studies with our new PAI system will help to elucidate various mechanisms of vascular-associated diseases and events.

Photoacoustic imaging of breast cancer: a mini review of system design and image features

“…In the subsequent generations, to increase the field of view, the rotational scanning is replaced by a rectilinear scan of the whole array in a spiral pattern. [45][46][47] In addition, the number of the array elements is increased to 512, and the central frequency is reduced to 2 MHz. The spiral scan is such that PA data acquired is at equidistant locations.…”

“…So far, US imaging could only be achieved using a secondary transducer array, which needs additional image co-registration. 47 Another hemispherical system implemented by Oraevsky et al 51 features an arc-shaped transducer that is rotated around the breast. This system, called the laser optoacoustic imaging system assembly (LOUISA-3D), consists of two subsystems-the PA subsystem and the US subsystem.…”

Twente Photoacoustic Mammoscope 2: system overview and three-dimensional vascular network images in healthy breasts

“…We contribute to the field of photoacoustic breast imaging with our PAM 2 system, which is different from other systems recently presented [15][16][17] in terms of illumination and detector specifications. We show that adding more illumination beams and changing the ratio of delivered energy to these beams alters the observed results.…”

“…Several other research groups are working in the field of photoacoustic tomographic breast imaging. Matsumoto et al 15 showed a (breast) imaging system (PAI-04) where a woman is prone on a bed with one breast inside a breast-holding cup. A hemispherical-shaped detector array (center frequency 4 MHz) is used to measure the ultrasound as the breast is illuminated by a large beam, directed at the ventral side of the breast.…”

Photoacoustic assessment of hemodynamic changes in foot vessels

“…It can afford high resolution images in deep tissue based on optical absorption. PAT has shown its ability in breast cancer , thyroid cancer , vascular examination , inflammatory arthritis and osteoarthritis , oral cancer , bone pathology and dermatology in human studies. PAT of vasculature can be achieved because hemoglobin is concentrated in blood vessels with strong optical absorption.…”