title: Impact of tissue photon attenuation in small animal cardiac PET imaging.
abstract: OBJECTIVE
  Tissue photon attenuation is one of the essential artifacts requiring correction in clinical cardiac positron emission tomography (PET) imaging. However, due to small body size its impact on diagnostic accuracy in small rodents is considered to be limited or even ignorable. The present cardiac PET study compares lean and obese rats to determine the influence of tissue attenuation on quantitative assessment as well as regional tracer distribution.
  
  
  METHODS
  A dedicated small animal PET system equipped with a57Co rotating source for transmission was used. To assess the impact of tissue attenuation in rats with different body sizes, cardiac18F-FDG -PET studies for Zucker diabetic fatty rats (obese rats) and Zucker lean rats (lean rats) were performed. The radiotracer activity reduction by attenuation was compared between the two groups. Regional tracer distribution calculated with and without attenuation correction was also assessed.
  
  
  RESULTS
  The chest diameter was significantly longer in obese than in lean rats (5.6±0.3cm in obese and 4.5±0.2cm in lean rats, p<0.0001). Whereas the activity reduction by attenuation was significantly greater in obese than in lean rats (44.1±2.5% and 5.1±3.1%, p<0.0001), the regional variation of tissue attenuation among the ventricular walls was minimal in both lean (p=0.73) and obese rats (p=0.65).
  
  
  CONCLUSIONS
  Attenuation correction is indispensable for accurate comparison of cardiac tracer activity between animals with different body size, whereas it can be omitted for evaluation of regional tracer distribution.
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany; Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hayakawa
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany; Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Yamane
authors.affiliation: Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany; Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Anahi-Paula
authors.initials: AP
authors.lastname: Arias-Loza
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany; Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shinaji
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany; Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wakabayashi
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Lapa
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany; Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Rudolf A
authors.initials: RA
authors.lastname: Werner
authors.affiliation: Division of Nuclear Medicine, Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, MD, United States.
authors.forename: Mehrbod S
authors.initials: MS
authors.lastname: Javadi
authors.affiliation: Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Theo
authors.initials: T
authors.lastname: Pelzer
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany; Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany. Electronic address: thiguchi@me.com.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Higuchi
mesh_terms: D000818:Animals; D016477:Artifacts; D057791:Cardiac Imaging Techniques; D019788:Fluorodeoxyglucose F18; D006321:Heart / Q000000981:diagnostic imaging*; D008297:Male; D009765:Obesity / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness / Q000000981:diagnostic imaging
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Attenuation correction; Cardiac PET; Small animal; Tissue photon attenuation