title: Thermoacoustic molecular imaging of small animals.
abstract: We have designed, constructed, and tested a thermoacoustic computed tomography (TCT) scanner for imaging optical absorption in small animals in three dimensions. The device utilizes pulsed laser irradiation (680-1064 nm) and a unique, 128-element transducer array. We quantified the isotropic spatial resolution of this scanner to be 0.35 mm. We describe a dual-wavelength subtraction technique for isolating optical dyes with TCT. Phantom experiments demonstrate that we can detect 5 fmol of a near-infrared dye (indocyanine green, ICG) in a 1-microL volume using dual-wavelength subtraction. Initial TCT imaging in phantoms and in two sacrificed mice suggests that three-dimensional, optical absorption patterns in small animals can be detected with an order of magnitude better spatial resolution and an order of magnitude better low-contrast detectability in small animals when compared to fluorescence imaging or diffusion optical tomography.
authors.affiliation: OptoSonics, Inc., 7210 Georgetown Road, Suite 400, Indianapolis, IN 46268, USA. rkruger@optosonics.com
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kruger
authors.forename: William L
authors.initials: WL
authors.lastname: Kiser
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Reinecke
authors.forename: Gabe A
authors.initials: GA
authors.lastname: Kruger
authors.forename: Kathy D
authors.initials: KD
authors.lastname: Miller
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000378:metabolism; D004396:Coloring Agents / Q000494:pharmacology; D004058:Diffusion; D004305:Dose-Response Relationship, Drug; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D007208:Indocyanine Green / Q000494:pharmacology; D007700:Kinetics; D016014:Linear Models; D051379:Mice; D008856:Microscopy, Fluorescence; D019047:Phantoms, Imaging; D013696:Temperature; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green