Phantom and clinical evaluation of Block Sequential Regularized Expectation Maximization (BSREM) reconstruction algorithm in 68Ga-PSMA PET-CT studies

Abstract

Purposewe aimed to investigate the effect of various β-value in BSREM algorithm under different lesion sizes, in order to determine an optimal penalty factor for clinical use. MethodsThe NEMA IQ phantom and 15 patients with prostate cancer were injected with 68Ga-PSMA and scanned by GE Discovery IQ PET/CT scanner. Images were reconstructed using OSEM and BSREM with different β-values and then background variability (BV), contrast recovery (CR), signal-to-noise ratio (SNR), and lung residual error (LE) from phantom data, and Signal-to-Background Ratio (SBR), contrast from clinical data were measured. ResultsThe increment of BV using β-value of 100 was 120% and the decrement of BV using β-value 1000 were 40.5% compared to OSEM. As the β decreased from 1000 to 100, the SUV max increased by 59% and 26.4% for sphere with diameter of 10 mm and 37 mm, respectively.Δ SNR (100-1000) % increased by 140.5 and 29.0 in the smallest and the largest sphere, respectively. The Δ LE OSEM-100 and Δ LE OSEM-1000 was − 41.1% and − 36.7% respectively. In the clinical study, the lowest SBR and contrast was related to the OSEM. The SBR and contrast, respectively increased by 69.7% and 71.8% in small lesions and 35.6% and 33% in large lesions, respectively, when β-value was decreased from 500 to 100. ConclusionsAs the lesion size decreased, the optimum β-value decreased. In both studies, a β value of 400 would be optimal for reconstruction of small lesions, whereas for large lesions in phantom and clinical studies respectively, β-value of 600 and 500 is recommended.

Optimizing scan time and bayesian penalized likelihood reconstruction algorithm in copper-64 PET/CT imaging: a phantom study

“…As demonstrated in figure 4(b), BPL resulted in significantly higher RC compared to OSEM-PSF (p < 0.05). This agrees with prior studies performed using other isotopes [27][28][29][30][31]. In particular, the phantom study using BPL reconstruction with F-18 by te Riet et al demonstrated RC decreased with increasing b and that all RC were increased relative to OSEM-PSF reconstruction [30].…”

“…In addition to F-18, the trends identified in this manuscript are further reinforced by a study conducted by Sadeghi et al, which examined BPL reconstruction in Ga-68 PSMA imaging. Their clinical results indicate that 400 b = can match noise levels achieved by OSEM-PSF reconstruction with a higher number of iterations [31]. CNR and SNR improve while RC decreases as a function of increasing ; b this means there will always be a tradeoff when optimizing the imaging protocol.…”

The effects of various penalty parameter values in Q.Clear algorithm for rectal cancer detection on 18F-FDG images using a BGO-based PET/CT scanner: a phantom and clinical study

“…Our previous research exclusively conducted a phantom study at only a lesion-to-background ratio of 4 (LBR 4:1) to evaluate Q.Clear in 68Ga-PSMA PET-CT examinations. We concluded that at LBR 4:1, Q.Clear with a β value of 400 is most effective for reconstructing small lesions, while larger lesions in the phantom benefit from β values of 600 [ 24 ]. Chen et al.…”