%0 Journal Article
%T Importance of Attenuation Correction (AC) for Small Animal PET Imaging
%A Henrik H. El Ali
%A Rasmus Poul Bodholdt
%A Jesper Tranekj£¿r J£¿rgensen
%A Rebecca Myschetzky
%A Andreas Kjaer
%J Diagnostics
%D 2012
%I MDPI AG
%R 10.3390/diagnostics2040042
%X The purpose of this study was to investigate whether a correction for annihilation photon attenuation in small objects such as mice is necessary. The attenuation recovery for specific organs and subcutaneous tumors was investigated. A comparison between different attenuation correction methods was performed. Methods: Ten NMRI nude mice with subcutaneous implantation of human breast cancer cells (MCF-7) were scanned consecutively in small animal PET and CT scanners (MicroPET TM Focus 120 and ImTek¡¯s MicroCAT TM II). CT-based AC, PET-based AC and uniform AC methods were compared. Results: The activity concentration in the same organ with and without AC revealed an overall attenuation recovery of 9¨C21% for MAP reconstructed images, i.e., SUV without AC could underestimate the true activity at this level. For subcutaneous tumors, the attenuation was 13 ¡À 4% (9¨C17%), for kidneys 20 ¡À 1% (19¨C21%), and for bladder 18 ¡À 3% (15¨C21%). The FBP reconstructed images showed almost the same attenuation levels as the MAP reconstructed images for all organs. Conclusions: The annihilation photons are suffering attenuation even in small subjects. Both PET-based and CT-based are adequate as AC methods. The amplitude of the AC recovery could be overestimated using the uniform map. Therefore, application of a global attenuation factor on PET data might not be accurate for attenuation correction.
%K attenuation correction
%K small animal
%K PET imaging
%K MicroPET
%K molecular imaging
%U http://www.mdpi.com/2075-4418/2/4/42