Model-Based Optoacoustic Image Reconstruction of Large Three-Dimensional Tomographic Datasets Acquired With an Array of Directional Detectors

Abstract

Image quality in 3-D optoacoustic (photoacoustic) tomography is greatly influenced by both the measurement system, in particular the number and spatial arrangement of ultrasound sensors, and the ability to account for the spatio-temporal response of the sensor element(s) in the reconstruction algorithm. Herein we present a reconstruction procedure based on the inversion of a time-domain forward model incorporating the spatial impulse response due to the shape of the transducer, which is subsequently applied in a tomographic system based on a translation-rotation scan of a linear detector array. The proposed method was also adapted to cope with the data-intensive requirements of high-resolution volumetric optoacoustic imaging. The processing of 2 · 10 (4) individual signals resulted in well-resolved images of both ~ 200 μm absorbers in phantoms and complex vascular structures in biological tissue. The results reported herein demonstrate that the introduced model-based methodology exhibits a better contrast and resolution than standard back-projection and model-based algorithms that assume point detectors. Moreover, the capability of handling large datasets anticipates that model-based methods incorporating the sensor properties can become standard practice in volumetric opto acoustic image formation.

Single-side access, isotropic resolution, and multispectral three-dimensional photoacoustic imaging with rotate-translate scanning of ultrasonic detector array

“…The journal version is the definitive version. 36 reduce background noise of the images and in particular the radial streaks (visible in figure 1 (I-B)) caused by projections outside of the region of higher sensitivity of the detectors (35,48).…”

“…Moreover, no closed-form analytical expression can be found for the SIR of cylindrically focused detector, which results in additional computation complexity (35,49). Practical implementations of more advanced reconstruction methods accounting for the EIR and the SIR of the detectors to improve image resolution are beyond the scope of this paper, but are of great interest for our rotate-translate system and will be considered in future studies.…”

Advanced optoacoustic methods for multiscale imaging of in vivo dynamics

“…Here image formation is based on reconstruction algorithms, such as e.g. back-projection or model-based inversions [54–57], analogous to those used in other tomographic imaging modalities. In fact, the first in vivo optoacoustic images from small animals were obtained with a tomographic optoacoustic system based on a cylindrically-focused transducer scanned around the head of a rat [58].…”

Sparsity‐based acoustic inversion in cross‐sectional multiscale optoacoustic imaging

“…In practice, this requirement necessitates scanning an ultrasound array around the specimen, leading to long imaging durations. 4,5 An alternative approach is the use of circular detection arrays cylindrically focused to the plane of interest. [6][7][8] By simultaneously reading out all the detection channels, a 2D cross-sectional optoacoustic image may be formed from a single laser pulse.…”

“…The advantage of the model-based approach is the ability to incorporate arbitrary detection geometries for which no exact closed-form solution exists. 4,14 In particular, model-based image reconstruction has been demonstrated for reducing image distortion and artifacts due to finite detector aperture or incomplete projection data. 15,16 Quite often, regularization is required in model-based inversion to suppress noise and artifacts in the reconstructed images by making assumptions on the nature of the expected optoacoustic image.…”