Impact of total variation regularized expectation maximization reconstruction on the image quality of 68Ga-PSMA PET: a phantom and patient study.

Abstract

OBJECTIVES\nTo investigate the impact of total variation regularized expectation maximization (TVREM) reconstruction on the image quality of 68Ga-PSMA-11 PET/CT using phantom and patient data.\n\n\nMETHODS\nImages of a phantom with small hot sphere inserts and 20 prostate cancer patients were acquired with a digital PET/CT using list-mode and reconstructed with ordered subset expectation maximization (OSEM) and TVREM with 7 penalisation factors between 0.01 and 0.42 for 2 and 3 minutes-per-bed (m/b) acquisition. The contrast recovery (CR) and background variability (BV) of the phantom, image noise of the liver, and SUVmax of the lesions were measured. Qualitative image quality was scored by two radiologists using a 5-point scale (1-poor, 5-excellent).\n\n\nRESULTS\nThe performance of CR, BV, and image noise, and the gain of SUVmax was higher for TVREM 2 m/b groups with the penalisation of 0.07 to 0.28 compared to OSEM 3 m/b group (all p < 0.05). The image noise of OSEM 3 m/b group was equivalent to TVREM 2 and 3 m/b groups with a penalisation of 0.14 and 0.07, while lesions SUVmax increased 15 and 20%. The highest qualitative score was attained at the penalisation of 0.21 (3.30 ± 0.66) for TVREM 2 m/b groups and the penalisation 0.14 (3.80 ± 0.41) for 3 m/b group that equal to or greater than OSEM 3 m/b group (2.90 ± 0.45, p = 0.2\u2009and p < 0.001).\n\n\nCONCLUSIONS\nTVREM improves lesion contrast and reduces image noise, which allows shorter acquisition with preserved image quality for PSMA PET/CT.\n\n\nADVANCES IN KNOWLEDGE\nTVREM reconstruction with optimised penalisation factors can generate higher quality PSMA-PET images for prostate cancer diagnosis.