Imaging Small-animal Whole-body Dynamics by Single-impulse Panoramic Photoacoustic Computed Tomography Lei Li a , Liren Zhu a, b , Cheng Ma c , Li Lin a, b , Junjie Yao d , Lidai Wang e , Konstantin Maslov a , Ruiying Zhang b , Wanyi Chen b , Junhui Shi a , Lihong V. Wang a * a Department of Medical Engineering, California Institute of Technology, 1200 E California Blvd. MC 136-93, Pasadena, CA 91125; b Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130; c Department of Electronic Engineering, Tsinghua University, Beijing, 100084, China; d Department of Biomedical Engineering, Duke University, Durham, NC, 27708; d Department of Biomedical Engineering, Duke University, Durham, NC, 27708; e Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong, China. *Correspondence to: L.V.W. (LVW@Caltech.edu) ABSTRACT Small animal whole-body imaging, providing physiological, pathological, and phenotypical insights into biological processes, is indispensable in preclinical research. With high spatiotemporal resolution and functional contrast, small animal imaging can visualize biological dynamics in vivo at whole-body scale, which can advance both fundamental biology and translational medicine. However, current non-optical imaging techniques lack either spatiotemporal resolution or functional contrasts, and pure optical imaging suffers from either shallow penetration (up to ~1 mm) or a poor resolution-to-depth ratio (~1/3). Here, we present a standalone system, termed single-impulse panoramic photoacoustic computed tomography (SIP-PACT), which overcomes all the above limitations. Our technology, with unprecedented performance, is envisioned to complement existing modalities for imaging entire small animals. As an optical imaging modality, SIP-PACT captures the high molecular contrast of endogenous substances such as hemoglobin, melanin, and lipid, as well as exogenous biomarkers, at the whole animal scale with full-view fidelity. Unlike other optical imaging methods, SIP-PACT sees through ~5 cm of tissue in vivo, and acquires cross-sectional images with an in-plane resolution of ~100 µm. Such capabilities allow us to image, for the first time, mouse whole- body dynamics in real time with clear sub-organ anatomical and functional details and without motion artifacts. SIP- PACT can capture transients of whole-body oxygen saturation and pulse wave propagation in vivo without labeling. In sum, we expect widespread applications of SIP-PACT as a whole-body imaging tool for small animals in fundamental biology, pharmacology, pathology, oncology, and other areas. Keywords: Single-impulse, whole-body imaging, small-animal imaging, photoacoustic computed tomography 1. INTRODUCTION Small animals, especially rodents, are essential models for preclinical studies, and they play an important role in modeling human physiology and development, in guiding the study of human diseases, and in devising effective treatments [1]. Previously, small-animal whole-body imaging has typically relied on non-optical approaches, including magnetic resonance imaging (MRI), X-ray computed tomography (X-ray CT), positron emission tomography (PET) or single-photon emission computed tomography (SPECT), and ultrasound tomography (UST) [2, 3]. Although these techniques provide deep penetration, they suffer from significant limitations. Optical imaging of biological tissue employs non-carcinogenic electromagnetic waves to provide extraordinary structural, functional, and molecular contrasts with either endogenous or exogenous agents [4-6]. Unfortunately, the application of conventional optical imaging technologies to small-animal whole-body imaging is impeded by the strong optical scattering of tissue, which prevents high-resolution imaging beyond the optical diffusion limit of ~1–2 mm in depth [2]. To date, photoacoustic tomography (PAT) is the only high-resolution optical imaging modality that breaks the optical diffusion limit [7]. Photoacoustic Photons Plus Ultrasound: Imaging and Sensing 2017, edited by Alexander A. Oraevsky, Lihong V. Wang, Proc. of SPIE Vol. 10064, 100640M · © 2017 SPIE · CCC code: 1605-7422/17/$18 · doi: 10.1117/12.2251593 Proc. of SPIE Vol. 10064 100640M-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 08/10/2017 Terms of Use: http://spiedigitallibrary.org/ss/termsofuse.aspx