Feasibility Study of Three-dimensional Co-registered Ultrasound and Photoacoustic Imaging for Cancer Detection and Visualization Andres Aguirre a , John Gamelin a , Puyun Guo b , Shikui Yan c and Quing Zhu a a Dept. of Electrical Engineering, University of Connecticut, Storrs, CT 06269 b Electrocore LLC, 51 Gibraltar Dr, Suite, Morris Plains, NJ 07950 c Siemens Molecular Imaging, 117 Village at Vanderbilt, Nashville, TN 37212 ABSTRACT Three-dimensional imaging is very valuable in detecting and visualizing lesions from multiple viewing angles. In addition, co-registered 3D imaging combining conventional ultrasound and photoacoustic tomography allows visualization of tissue structures with simultaneous structural and functional information. We have developed a 1280 element 3D ultrasound imaging system based on a 1.75D acoustic array. Complete volumetric images over the full scanning range can be achieved in a few minutes. In conjunction with a Ti:Sapphire laser, the system has been used for photoacoustic imaging. We present 3D co-registered images obtained with the system. Ultrasound and photoacoustic co-registered images of phantoms with different optical and acoustical properties are shown to demonstrate its advantage in cancer detection. Keywords: Photoacoustic, ultrasound, tumor, cancer, imaging. INTRODUCTION In the past two decades, medical ultrasound has become an indispensable imaging modality due to its flexibility and non-invasive character. Moreover, owing to continuous improvements in image quality, it is progressively achieving a greater role in radiology. In conventional pulse-echo ultrasound, the transducer is manipulated to get a series of two- dimensional images, which are mentally combined by the operator to form an impression of the three-dimensional anatomy and pathology. This mental transformation is not only time- consuming and inefficient, but is also more importantly, variable and subjective. Thus, the success of the diagnostic is largely dependant on the skill and experience of the operator. Even more, because in conventional 2D ultrasound the transducer determines the location and orientation of the images, some views are impossible to achieve because of restrictions imposed by the patient’s anatomy or position. [1]. These disadvantages of 2D ultrasound can be overcome by 3D ultrasound imaging. In theory, 2D arrays would be the ideal tool to use for 3D volumetric imaging. However, the required number of array elements increases rapidly by N 2 , where N is the number of elements at either dimension. Thus, the large number of elements in 2D arrays bring considerable problems and technical challenges like, fabrication, crosstalk, interconnection, signal-to-noise ratio and a complex electronics [2]. 1.75D arrays have been developed to achieve a balance between 3D imaging capability and system complexity. Compared to 2D arrays, 1.75D arrays have similar element size in azimuth, but fewer and larger elements in elevation; thus decreasing system complexity at the expense of smaller beam steering range in elevation [3,4]. Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, edited by Alexander A. Oraevsky, Lihong V. Wang, Proc. of SPIE Vol. 6856, 68562A, (2008) · 1605-7422/08/$18 · doi: 10.1117/12.775208 Proc. of SPIE Vol. 6856 68562A-1 2008 SPIE Digital Library -- Subscriber Archive Copy