Importance of Attenuation Correction (AC) for Small Animal PET Imaging

Diagnostics

Henrik H. El Ali¹  Rasmus Poul Bodholdt²  Jesper Tranekjær Jørgensen²  Rebecca Myschetzky² 

[1] Cluster for Molecular Imaging, Faculty of Health Sciences & Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark;

关键词: attenuation correction;    small animal;    PET imaging;    MicroPET;    molecular imaging;   

DOI  :  10.3390/diagnostics2040042

来源: mdpi

【 摘 要 】

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 9–21% for MAP reconstructed images, i.e., SUV without AC could underestimate the true activity at this level. For subcutaneous tumors, the attenuation was 13 ± 4% (9–17%), for kidneys 20 ± 1% (19–21%), and for bladder 18 ± 3% (15–21%). 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.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.