Computational and Mathematical Methods in Medicine
Volume 2013 (2013), Article ID 103476, 12 pages
Research Article

Attenuation Correction for Small Animal PET Images: A Comparison of Two Methods

1Medical Physics Department, University Hospital S. Orsola-Malpighi, Via Massarenti 9, 40138 Bologna, Italy
2Medical Physics Department, IRCCS Fondazione Maugeri, Via Salvatore Maugeri 4, 27100 Pavia, Italy
3Medical Physics Department, IRCCS San Raffaele, Via Olgettina 60, 20132 Milano, Italy

Received 18 December 2012; Revised 9 March 2013; Accepted 10 March 2013

Academic Editor: Peng Feng

Copyright © 2013 Daniela D'Ambrosio et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In order to extract quantitative parameters from PET images, several physical effects such as photon attenuation, scatter, and partial volume must be taken into account. The main objectives of this work were the evaluation of photon attenuation in small animals and the implementation of two attenuation correction methods based on X-rays CT and segmentation of emission images. The accuracy of the first method with respect to the beam hardening effect was investigated by using Monte Carlo simulations. Mouse- and rat-sized phantoms were acquired in order to evaluate attenuation correction in terms of counts increment and recovery of uniform activity concentration. Both methods were applied to mice and rat images acquired with several radiotracers such as -FDG, 11C-acetate, 68Ga-chloride, and -NaF. The accuracy of the proposed methods was evaluated in heart and tumour tissues using -FDG images and in liver, kidney, and spinal column tissues using -acetate, -chloride, and -NaF images, respectively. In vivo results from animal studies show that, except for bone scans, differences between the proposed methods were about 10% in rats and 3% in mice. In conclusion, both methods provide equivalent results; however, the segmentation-based approach has several advantages being less time consuming and simple to implement.