Abstract
Background: The sensitivity of radiomic features to several confounding factors, such as image reconstruction settings, makes clinical use challenging. In order to investigate the impact of harmonized image reconstructions on feature consistency, a multicenter phantom study was performed using 3D printed phantom inserts reflecting realistic tumor shapes and heterogeneity uptakes. Methods: Tumours extracted from real PET/CT scans of patients with Non-Small Cell Lung Cancer served as model for three 3D printed phantom inserts. Different heterogeneity pattern were realized by printing separate compartments that can be filled with different activity solutions. The inserts were placed in the NEMA image quality phantom and scanned various times. First, a list-mode scan was acquired and five statistical equal replicates were reconstructed. Secondly, the phantom was scanned four times on the same scanner. Thirdly, the phantom was scanned on six different PET/CT systems. All images were reconstructed using EARL-compliant and the locally clinically-preferred reconstructions. The EARL-compliant reconstructions were performed without (EARL1) or with (EARL2) point-spread function (PSF). Images were analyzed with and without resampling to 2 mm cubic voxels. Images were discretized with a fixed bin width (FBW) of 0.25 and a fixed bin number (FBN) of 64 bins. The intraclass correlation coefficient (ICC) of each scan setup was calculated and compared across reconstruction settings. An ICC above 0.75 was regarded as high. Results: The percentage of features yielding a high ICC was the largest for the statistical equal replicates (70%- 91% for FBN, 90%-96% for FBW discretization). For the scans acquired on the same system, the percentage decreased, but the majority of features still resulted in a high ICC (FBN: 52%-63%, FBW: 75%-85%). The percentage of features yielding a high ICC decreased more in the multicenter setting. In this case, the percentage of features yielding a high ICC was larger for images reconstructed with (harmonizing) EARL-compliant reconstructions: e.g. 40% for EARL1, 60% for EARL2 vs. 21% for the clinically-preferred setting for FBW discretization. When discretized with FBW and resampled to isotropic voxels, this benefit was more pronounced. Conclusion: EARL-compliant reconstructions harmonize a wide range of radiomic features. FBW discretization and a sampling to isotropic voxels, pronounces the benefits of EARL-compliant reconstructions.
- Image Reconstruction
- PET/CT
- Other
- 18F-FDG PET/CT radiomic features
- feature harmonization
- image reconstruction
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.