title: 18F, 11C and 68Ga in small animal PET imaging. Evaluation of partial volume correction methods.
abstract: OBJECTIVE
  The partial volume effect (PVE) significantly affects quantitative accuracy in PET. In this study we used a micro-hollow sphere phantom filled with 18F, 11C or 68Ga to evaluate different partial volume correction methods (PVC). Additionally, phantom data were applied on rat brain scans to evaluate PVC methods on in vivo datasets.
  
  
  METHODS
  The four spheres (7.81, 6.17, 5.02, 3.90 mm inner diameter) and the background region were filled to give sphere-to-background (sph/bg) activity ratios of 20 : 1, 10 : 1, 5 : 1 and 2 : 1. Two different acquisition and reconstruction protocols and three radionuclides were evaluated using a small animal PET scanner. From the obtained images the recovery coefficients (RC) and contrast recovery coefficients (CRC) for the different sph/bg ratios were calculated. Three methods for PVC were evaluated: a RC based, a CRC based and a volume of interest (VOI) based method. The most suitable PVC methods were applied to in vivo rat brain data.
  
  
  RESULTS
  RCs were shown to be dependent on the radionuclide used, with the highest values for 18F, followed by 11C and 68Ga. The calculated mean CRCs were generally lower than the corresponding mean RCs. Application of the different PVC methods to rat brain data led to a strong increase in time-activity curves for the smallest brain region (entorhinal cortex), whereas the lowest increase was obtained for the largest brain region (cerebellum).
  
  
  CONCLUSIONS
  This study was able to show the importance and impact of PVE and the limitations of several PVC methods when performing quantitative measurements in small structures.
authors: J
authors: J
authors: Muellauer
authors: R
authors: R
authors: Willimayer
authors: A L
authors: AL
authors: Goertzen
authors: T
authors: T
authors: Wanek
authors: O
authors: O
authors: Langer
authors: W
authors: W
authors: Birkfellner
authors: Claudia Kuntner, Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, Austria, Tel. +43/505 50 34 71, Fax +43/505 50 34 73, E-mail: claudia.kuntner@ait.ac.at.
authors: C
authors: C
authors: Kuntner
mesh_terms: D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging*; D002250:Carbon Radioisotopes; D005260:Female; D019788:Fluorodeoxyglucose F18; D005710:Gallium Radioisotopes; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000662:veterinary; D049268:Positron-Emission Tomography / Q000379:methods / Q000662:veterinary*; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002250:Carbon Radioisotopes; D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: PET; Positron emission tomography; partial volume correction; partial volume effect; quantification; recovery coefficient