title: A rat head holder for simultaneous scanning of two rats in small animal PET scanners: design, construction, feasibility testing and kinetic validation.
abstract: To reduce imaging costs, we designed a head holder for scanning two rats simultaneously in small animal PET scanners. Our goals were (i) to maintain high sensitivity and (ii) to minimize repositioning error between scans.
  
  
  METHODS
  A semi-stereotaxic dual rat head holder was designed and constructed for dual rat scanning in our IndyPET-II scanner and the commercial microPET P4. It was also used for single rat scanning in a small-bore, high-resolution animal scanner ("ISAP"). Positional repeatability was validated via multiple [11C]Raclopride scans of a single rat on different days. Accuracy of repositioning was determined by visual comparison of images, and by metrics derived through image alignment. Kinetic validation was assessed via analysis of [18F]Fluorodeoxyglucose ([18F]FDG) dynamic PET studies of six rats. Each rat was scanned twice: once individually, with brain positioned at the center of field of view (CFOV), and once with a partner, with brain away from CFOV. Both rats were injected with FDG during each dual rat session. Patlak uptake constants (Ki) were calculated from whole brain images. Effects of attenuation and scatter correction on single versus dual scan images were explored.
  
  
  RESULTS
  Image comparison and alignment metrics indicated excellent repositioning of rats. Scaled time-activity-curves from single and dual rat scans were indistinguishable. Average single and dual scan Ki values differed by only 6.3+/-7.5%.
  
  
  CONCLUSIONS
  Dual rat scanning in a semi-stereotaxic holder is practical for economical small animal scanning and does not compromise kinetic accuracy of [18F]FDG dynamic scan data.
authors.affiliation: Biomedical Engineering Department, Purdue School of Engineering & Technology, Indianapolis, IN 46202, USA. techeng@iupui.edu
authors.forename: Tee Ean
authors.initials: TE
authors.lastname: Cheng
authors.forename: Karmen K
authors.initials: KK
authors.lastname: Yoder
authors.forename: Marc D
authors.initials: MD
authors.lastname: Normandin
authors.forename: Shannon L
authors.initials: SL
authors.lastname: Risacher
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Converse
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Hampel
authors.forename: Michael A
authors.initials: MA
authors.lastname: Miller
authors.forename: Evan D
authors.initials: ED
authors.lastname: Morris
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D005240:Feasibility Studies; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D006257:Head / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods*; D020891:Raclopride / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013238:Stereotaxic Techniques; D051598:Whole Body Imaging / Q000379:methods
chemical_list: D018492:Dopamine Antagonists; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D020891:Raclopride