  Significance: Dynamic photoacoustic computed tomography (PACT) is a valuable
technique for monitoring physiological processes. However, current dynamic PACT
techniques are often limited to 2D spatial imaging. While volumetric PACT
imagers are commercially available, these systems typically employ a rotating
gantry in which the tomographic data are sequentially acquired. Because the
object varies during the data-acquisition process, the sequential
data-acquisition poses challenges to image reconstruction associated with data
incompleteness. The proposed method is highly significant in that it will
address these challenges and enable volumetric dynamic PACT imaging with
existing imagers. Aim: The aim of this study is to develop a spatiotemporal
image reconstruction (STIR) method for dynamic PACT that can be applied to
commercially available volumetric PACT imagers that employ a sequential
scanning strategy. The proposed method aims to overcome the challenges caused
by the limited number of tomographic measurements acquired per frame. Approach:
A low-rank matrix estimation-based STIR method (LRME-STIR) is proposed to
enable dynamic volumetric PACT. The LRME-STIR method leverages the
spatiotemporal redundancies to accurately reconstruct a 4D spatiotemporal
image. Results: The numerical studies substantiate the LRME-STIR method's
efficacy in reconstructing 4D dynamic images from measurements acquired with a
rotating gantry. The experimental study demonstrates the method's ability to
faithfully recover the flow of a contrast agent at a frame rate of 0.1 s even
when only a single tomographic measurement per frame is available. Conclusions:
The LRME-STIR method offers a promising solution to the challenges faced by
enabling 4D dynamic imaging using commercially available volumetric imagers. By
enabling accurate 4D reconstruction, this method has the potential to advance
preclinical research.
