title: Coregistration of diffuse optical spectroscopy and magnetic resonance imaging in a rat tumor model.
abstract: We report coregistration of near-infrared diffuse optical spectroscopy (DOS) and magnetic resonance imaging (MRI) for the study of animal model tumors. A combined broadband steady-state and frequency-domain apparatus was used to determine tissue oxyhemoglobin, deoxyhemoglobin, and water concentration locally in tumors. Simultaneous MRI coregistration provided structural (T2-weighted) and contrast-enhanced images of the tumor that were correlated with the optical measurements. By use of Monte Carlo simulations, the optically sampled volume was superimposed on the MR images, showing precisely which tissue structure was probed optically. DOS and MRI coregistration measurements were performed on seven rats over 20 days and were separated into three tumor tissue classifications: viable, edematous, and necrotic. A ratio of water concentration to total hemoglobin concentration, as measured optically, was performed for each tissue type and showed values for edematous tissue to be greater than viable tissue (1.2 +/- 0.49 M/microM versus 0.48 +/- 0.15 M/microM). Tissue hemoglobin oxygen saturation (StO2) also showed a large variation between tissue types: viable tissue had an optically measured StO2 value of 61 +/- 5%, whereas StO2 determined for necrotic tissue was 43 +/- 6%.
authors.affiliation: Laser Microbeam and Medical Program, Beckman Laser Institute, University of California Irvine, Irvine, California 92612, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Merritt
authors.forename: Frederic
authors.initials: F
authors.lastname: Bevilacqua
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Durkin
authors.forename: David J
authors.initials: DJ
authors.lastname: Cuccia
authors.forename: Ryan
authors.initials: R
authors.lastname: Lanning
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Tromberg
authors.forename: Gultekin
authors.initials: G
authors.lastname: Gulsen
authors.forename: Hon
authors.initials: H
authors.lastname: Yu
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Orhan
authors.initials: O
authors.lastname: Nalcioglu
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000818:Animals; D005260:Female; D008279:Magnetic Resonance Imaging; D009368:Neoplasm Transplantation; D055095:Optics and Photonics; D051381:Rats; D011916:Rats, Inbred F344; D012878:Skin Neoplasms / Q000175:diagnosis*