Breathing-induced Errors in Quantification and Description of Dominant Intra-Prostatic Lesions (Dils) in PET Images: A Simulation Study by Means of The ۴D NCAT Phantom

Background: Respiratory movement and the motion range of the diaphragm can affect the quality and quantity of prostate images.Objective: This study aimed to investigate the magnitude of respiratory-induced errors to determine Dominant Intra- prostatic Lesions (DILs) in positron emission tomography (PET) images.Material and Methods: In this simulation study, we employed the ۴D NURBS-based cardiac-torso (۴D-NCAT) phantom with a realistic breathing model to simulate the respiratory cycles of a patient to assess the displacement, volume, maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), signal to noise ratio (SNR), and the contrast of DILs in frames within the respiratory cycle.Results: Respiration in a diaphragm motion resulted in the maximum superior-inferior displacement of ۳.۹ and ۶.۱ mm, and the diaphragm motion amplitudes of ۲۰ and ۳۵ mm. In a no-motion image, the volume measurement of DILs had the smallest percentage of errors. Compared with the no-motion method, the percentages of errors in the average method in ۲۰ and ۳۵ mm- diaphragm motion were ۲۵% and ۱۰۵%, respectively. The motion effect was significantly reduced in terms of the values of SUVmax and SUVmean in comparison with the values of SUVmax and SUVmean in no- motion images. The contrast values in respiratory cycle frames were at a range of ۳.۳-۱۹.۲ mm and ۶.۵-۴۶ for diaphragm movements’ amplitudes of ۲۰ and ۳۵ mm. Conclusion: The respiratory movement errors in quantification and delineation of DILs were highly dependent on the range of motion, while the average method was not suitable to precisely delineate DILs in PET/CT in the dose-painting technique.