The Impact of Attenuation Correction on Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Image Quality: A Phantom Study

Objective:The quality of positron emission tomography/computed tomography (PET/CT) and PET/magnetic resonance (MR) images is a critical factor affecting the diagnostic reliability of clinical studies. An image quality (IQ) phantom is used to evaluate PET IQ. This study aims to acquire PET IQ phantom images on PET/CT and PET/MR systems and investigate the effects of attenuation correction on IQ.Materials and Methods:The PET IQ phantom was filled with F-18 fluorodeoxyglucose to achieve a lesion/background ratio of 4/1. The phantom was imaged separately on two different PET/CT scanners and one PET/MR scanner. Region of interest (ROIs) was drawn on both raw and attenuation-corrected images. Contrast and contrast-to-noise ratios (CNRs) were calculated from ROI counts.Results:For the smallest lesion with a diameter of 10 mm without attenuation correction, the contrast values in PET/CT and PET/MR images were found to be 1.32, 1.68, and 1.76, respectively. In attenuation-corrected images of the same lesion, the contrast values were 1.55, 1.89, and 2.22, respectively. The CNR values for the attenuation-corrected 10 cm lesion were 13.92, 12.05, and 13.36, respectively.Conclusion:Attenuation correction significantly improved IQ, with attenuation-corrected images demonstrating higher contrast and CNR values.