KEY TAKEAWAYS
- The study aimed to investigate the impact of the BPL reconstruction algorithm in PSMA PET/CT for assessing response to [177Lu]Lu-PSMA-617 in patients with mCRPC.
- Researchers noticed that BPL and OSEM reconstructions in PSMA PET/CT yield similar results, supporting their interchangeable use in clinical practice.
PSMA PET/CT is a predictive and prognostic biomarker for determining response to [177Lu]Lu-PSMA-617 in patients with metastatic castration-resistant prostate cancer (mCRPC). However, thresholds defined to date may not be generalizable to newer image reconstruction algorithms. The Bayesian penalized likelihood (BPL) reconstruction algorithm is a novel technique that could potentially improve contrast while minimizing the introduction of image noise.
Narjess Ayati and the team aimed to compare the quantitative parameters obtained using BPL and the Ordered Subset Expectation Maximization (OSEM) reconstruction algorithms.
They performed an inclusive analysis on 50 patients with consecutive metastatic castration-resistant prostate cancer (mCRPC) who underwent [68Ga]Ga-PSMA-11 PET/CT using OSEM reconstruction to assess suitability for [177Lu]Lu-PSMA-617 therapy. The BPL algorithm was then retrospectively applied to reconstruct the same PET raw data.
Quantitative and volumetric measurements were calculated using both reconstruction methods, including tumor standardized uptake value (SUV)max, SUVmean, and Molecular Tumor Volume (MTV-PSMA). Results were compared using Bland-Altman analysis and Pearson correlation coefficient, including subgroups with low and high-volume disease burdens (MTV-PSMA cut-off 40 mL).
The SUVmax and SUVmean were higher, and MTV-PSMA was lower in the BPL reconstructed images compared to the OSEM group, with a mean difference of 8.4 (17.5%), 0.7 (8.2%) and -21.5 mL (-3.4%), respectively. There was a strong correlation between the calculated SUVmax, SUVmean, and MTV-PSMA values in the OSEM and BPL reconstructed images (Pearson r values of 0.98, 0.99, and 1.0, respectively). No patients were reclassified from low to high volume disease or vice versa when switching from OSEM to BPL reconstruction.
The study concluded that the quantitative and volumetric parameters derived from [68Ga]Ga-PSMA-11 PET/CT using BPL and OSEM reconstruction methods exhibit a strong correlation. The differences observed, particularly in SUVmean, are proportionally small and do not carry clinical significance. Therefore, both reconstruction methods are deemed acceptable without impacting quantitative or volumetric findings. However, for longitudinal comparison, maintaining consistency in the choice of reconstruction method is recommended to ensure reliability and consistency over time.
The study received no funds.
Source: https://pubmed.ncbi.nlm.nih.gov/38711135/
Ayati N, McIntosh L, Buteau J, et al. (2024). “Comparison of quantitative whole body PET parameters on [68Ga]Ga-PSMA-11 PET/CT using ordered Subset Expectation Maximization (OSEM) vs. bayesian penalized likelihood (BPL) reconstruction algorithms in men with metastatic castration-resistant prostate cancer.” Cancer Imaging. 2024 May 6;24(1):57. doi: 10.1186/s40644-024-00702-x. PMID: 38711135; PMCID: PMC11075202.
