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Am J Nucl Med Mol Imaging 2012;2(4):405-414
Original Article
Dual tracer imaging of SPECT and PET probes in living mice using a sequential 
protocol
Sarah E Chapman*, Justin M Diener*, Todd A Sasser*, Carlos Correcher, Antonio J González, Tony Van Avermaete, W Matthew Leevy
Freimann Life Science Center, University of Notre Dame, 400 Galvin Life Science, Notre Dame, IN 46556, USA; Department of 
Chemistry and Biochemistry, 236 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA; Carestream 
Molecular Imaging, 4 Research Drive, Woodbridge, CT 06525, USA; Oncovision, Ciudad Politécnica de la Innovación, Camino de 
Vera s/n, E-46022 Valencia, Spain; Notre Dame Integrated Imaging Facility, Notre Dame, IN 46556, USA. *These authors contributed 
equally to this work.
Received August 8, 2012; Accepted August 28, 2012; Epub October 15, 2012; Published October 30, 2012
Abstract: Over the past 20 years, multimodal imaging strategies have motivated the fusion of Positron Emission Tomography (PET) 
or Single Photon Emission Computed Tomography (SPECT) scans with an X-ray computed tomography (CT) image to provide 
anatomical information, as well as a framework with which molecular and functional images may be co-registered. Recently, 
pre-clinical nuclear imaging technology has evolved to capture multiple SPECT or multiple PET tracers to further enhance the 
information content gathered within an imaging experiment. However, the use of SPECT and PET probes together, in the same 
animal, has remained a challenge. Here we describe a straightforward method using an integrated trimodal imaging system and a 
sequential dosing/acquisition protocol to achieve dual tracer imaging with 99mTc and 18F isotopes, along with anatomical CT, on an 
individual specimen. Dosing and imaging is completed so that minimal animal manipulations are required, full trimodal fusion is 
conserved, and tracer crosstalk including down-scatter of the PET tracer in SPECT mode is avoided. This technique will enhance the 
ability of preclinical researchers to detect multiple disease targets and perform functional, molecular, and anatomical imaging on 
individual specimens to increase the information content gathered within longitudinal in vivo studies. (ajnmmi1208003)
Keywords: Dual tracer imaging, trimodal imaging, Positron Emission Tomography (PET), Single Photon Emission Computed 
Tomography (SPECT), X-ray Computed Tomography (CT), nuclear imaging
Address all correspondence to:
Dr. W Matthew Leevy
Notre Dame Integrated Imaging Facility, University of Notre Dame
Notre Dame, IN 46556, USA.
E-mail: wleevy@nd.edu