Real-time photoacoustic and ultrasound imaging: a simple solution for clinical ultrasound systems with linear arrays

Abstract

Recent clinical studies have demonstrated that photoacoustic imaging (PAI) provides important diagnostic information during a routine breast exam for cancer. PAI enhances contrast between blood vessels and background tissue, which can help characterize suspicious lesions. However, most PAI systems are either not compatible with commercial ultrasound systems or inefficiently deliver light to the region of interest, effectively reducing the sensitivity of the technique. To address and potentially overcome these limitations, we developed an accessory for a standard linear ultrasound array that optimizes light delivery for PAI. The photoacoustic enabling device (PED) exploits an optically transparent acoustic reflector to help direct laser illumination to the region of interest. This study compares the PED with standard fiber bundle illumination in scattering and non-scattering media. In scattering media with the same incident fluence, the PED enhanced the photoacoustic signal by 18 dB at a depth of 5 mm and 6 dB at a depth of 20 mm. To demonstrate in vivo feasibility, we also used the device to image a mouse with a pancreatic tumor. The PED identified blood vessels at the periphery of the tumor, suggesting that PAI provides complementary contrast to standard pulse echo ultrasound. The PED is a simple and inexpensive solution that facilitates the translation of PAI technology to the clinic for routine screening of breast cancer.

Photoacoustic imaging of carotid artery atherosclerosis

“…There will be a strong PA signal generated near the surface of the transducer, 11 and incomplete overlap between the noncollinear light and US receiving beams, leading to signal generation outside the imaging plane. 12 We, therefore, propose to image the CA by means of interstitial illumination (from the pharynx) and external (neck side) US detection, aiming to circumvent the aforementioned problems [ Fig. 1(a)].…”

Tracking delivery of a drug surrogate in the porcine heart using photoacoustic imaging and spectroscopy

“…Specifically, the PED held both the optical components and linear US array (Zonare L10-5, 7.1-MHz center frequency, and 5-MHz bandwidth) for coregistered PE and PA imaging, which has been previously described. 19,20 Furthermore, the PED allowed for coalignment between the optical illumination and plane of US detection. Briefly, light from the fiber passed through a cylindrical lens to provide line illumination at the surface of the tissue.…”

Full-view photoacoustic tomography using asymmetric distributed sensors optimized with compressed sensing method

“…Increasing the amount of sensors may lead to better image quality, yet resulting in longer calculating time and the increase of system cost. Traditionally, linear array sensors are frequently used for their accessibility and convenience [23]. However, the image boundaries perpendicular to the longer axis of the array will be seriously blurred due to the limited-view effect, and only the boundaries within the receive range can be recovered.…”