Photoacoustic computed tomography of human extremities

Abstract

We present a method of imaging angiographic structures in human extremities, including hands, arms, legs, and feet, using a newly developed photoacoustic computed tomography (PACT) system. The system features deep penetration (1.8 cm in muscular tissues) with high spatial and temporal resolutions. A volumetric image is acquired within 5 to 15 s while each cross sectional image is acquired within 100 μs. Therefore, we see no blurring from motion in the imaging plane. Longitudinal and latitudinal cross-sectional images of a healthy volunteer clearly show the vascular network of each appendage and highlight the system's ability to image major and minor vasculatures, without the use of an external contrast or ionizing radiation. We also track heartbeatinduced arterial movement at a two-dimensional frame rate of 10 Hz. This work substantiates the idea that PACT could be used as a noninvasive method for imaging human vasculatures.

Recent advances in photoacoustic contrast agents for in vivo imaging

“…Using blood as the endogenous contrast, PAT could image small‐animal whole‐body including internal organs such as heart, liver, spleen, kidney, spine at high resolution (Fehm et al, ; L. Li et al, ; D. Wang et al, ). PAT was also successfully applied for imaging human organs such as whole‐breast (Lin et al, ), skin (Schwarz, Aguirre, et al, ), thyroid gland (Dima & Ntziachristos, ), finger joints (Deng & Li, ), hands, feet, wrist, forearm, leg, bicep (Wray et al, ) using blood as the main contrast. In all these applications, blood absorption at 1,064 nm was used to image the anatomy of blood vessels deep inside animal body and human organs.…”

MEMS Ultrasound Transducers for Endoscopic Photoacoustic Imaging Applications

“…Thanks to the advantages described above, PAI has been extensively exploited in brain functional imaging [ 10 , 11 ], early cancer detection [ 12 , 13 ], vascular visualization [ 14 , 15 , 16 ], and diagnosis of arthritis [ 17 , 18 ]. Most of these efforts are based on benchtop PAI systems.…”

Transcranial photoacoustic computed tomography based on a layered back-projection method

“…Intrinsically sensitive to optical absorption with a 100 % relative sensitivity, PACT can measure the concentrations of both oxyhemoglobin (HbO 2 ) and HbR based on their distinct spectral signatures in a proportional relationship, allowing quantifications of both concentrations [ 14 ]. PACT systems can be transportable, open, and quiet, minimizing site requirements and patient/subject stress [ 15 , 16 ].…”