Optimal CT breathing protocol for combined thoracic PET/CT

AJR Am J Roentgenol. 2006 Nov;187(5):1357-60. doi: 10.2214/AJR.05.1427.


Objective: The objective of this study was to determine the optimal breathing protocol for combined PET/CT scans of the thorax.

Subjects and 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.

Conclusion: 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.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Fluorodeoxyglucose F18
  • Humans
  • Male
  • Middle Aged
  • Positron-Emission Tomography / methods*
  • Radiography, Thoracic / methods*
  • Radiopharmaceuticals
  • Respiration*
  • Thorax / diagnostic imaging*
  • Tomography, X-Ray Computed / methods*
  • Whole Body Imaging / methods


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18