title: Optimal CT breathing protocol for combined thoracic PET/CT.
abstract: OBJECTIVE
  The objective of this study was to determine the optimal breathing protocol for combined PET/CT scans of the thorax.
  
  
  METHODS
  Eighty combined PET/CT scans were obtained in 64 patients (30 women, 34 men; mean age, 57 years; range, 19-86 years). The 80 PET/CT scans consisted of five group of patients (16 PET/CT scans per group) who underwent whole-body combined 18F-FDG PET/CT with different CT breathing protocols: expiration, mid suspended breath-hold, quiet breathing, small breath in, and regular breath in. The quality of alignment was analyzed at the diaphragm, aortic arch, heart, thoracic spine, and lung apices using a scale of ratings from 1 (very poor) to 5 (excellent). The Kruskal-Wallis test was used to compare alignment between breathing protocols for each anatomic reference point.
  
  
  RESULTS
  Alignment of the PET and CT data sets was excellent with three breathing protocols: expiration, mid suspended breath-hold, and quiet breathing, with no statistical differences. Significant misalignment occurred at the diaphragm (p < 0.0001) and heart (p < 0.0001) with the small breath-in and regular breath-in techniques.
  
  
  CONCLUSIONS
  Excellent image fusion of combined PET/CT data sets in the thorax, especially at the diaphragm and heart, can be achieved with expiration, mid suspended breath-hold, or quiet breathing. Quiet breathing is recommended for optimal patient comfort during acquisition of attenuation-correction CT data sets.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, FND 202, 55 Fruit St., Boston, MA 02114, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Gilman
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Fischman
authors.forename: Vikram
authors.initials: V
authors.lastname: Krishnasetty
authors.forename: Elkan F
authors.initials: EF
authors.lastname: Halpern
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Aquino
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D019275:Radiopharmaceuticals; D012119:Respiration; D013909:Thorax / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging / Q000379:methods
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18