Improvement of image quality for small lesion sizes in ۱۸F-FDG prone breast silicon photomultiplier-based PET/CT imaging

Objective(s): We investigated image quality and standardized uptake values (SUVs) for different lesion sizes using clinical data generated by ۱۸F-FDG-prone breast silicon photomultiplier (SiPM)-based positron emission tomography/computed tomography (PET/CT).Methods: We evaluated the effect of point-spread function (PSF) modeling and Gaussian filtering (Gau) and determined the optimal reconstruction conditions. We compared the signal-to-noise ratio (SNR), contrast, %coefficient of variation (%CV), SUV, and Likert scale score between ordered-subset expectation maximization (OSEM) time-of-flight (TOF) and OSEM+TOF+PSF in phantom and clinical studies. The conventional image was generated with OSEM+TOF_Gau ۶ mm. The National Electrical Manufacturers Association body phantom with ۱۰-mm hot sphere data was acquired for ۵ min. Twenty-six patients (۴۰ lesions, ranging from ۳.۷ to ۶۳.۰ mm) were examined using prone breast PET/CT with a breast positioner for breast cancer staging. PET data were acquired ۱۲۵±۹.۷ min after intravenous injection of ۲۲۰±۱۶.۱ MBq at ۵ min/bed.Results: In the phantom study, a high SNR was obtained from a ۳- to ۵-mm Gaussian filter for OSEM+TOF+PSF. The contrast obtained with OSEM+TOF without Gaussian filtering was superior to that obtained with OSEM+TOF+PSF_Gau ۴ mm. In the clinical study, the image quality depended on lesion size. The average SNR was significantly higher at ۴۰.۸% for lesions >۲۰ mm with OSEM+TOF_Gau ۶ mm than with OSEM+TOF without Gaussian filtering. The average contrast for lesions ≤۱۰ mm was significantly higher by ۴۲.۰% with OSEM+TOF without Gaussian filtering than with OSEM+TOF_Gau ۶ mm. The average SUVmax of OSEM+TOF without Gaussian filtering significantly increased by ۵۳.۳% for lesions ≤۱۰ mm.Conclusion: OSEM+TOF without Gaussian filtering provided good contrast and quantitative value for small lesions.

کلیدواژه ها:

Breast Cancer ، Digital PET ، Prone position