Impact of Image Reconstruction on Quantitative Analysis of 18F-FDG PET in Epilepsy Evaluation: A Preliminary Study

Naghmeh  Firouzi; Ali Asghar  Parach; Kaveh  Tanha; Mohammad Sadegh  Rostami; Parham  Geramifar

doi:10.18502/fbt.v13i2.21944

Naghmeh Firouzi Department of Medical Physics, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Ali Asghar Parach Institut de Recherche en Cancérologie de Montpellier, INSERM U1194 – ICM, France
Kaveh Tanha Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Sadegh Rostami Faculty of Psychology, Tarbiat Modarres University, Tehran, Iran
Parham Geramifar Research Center for Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/fbt.v13i2.21944

Keywords: Positron Emission Tomography; Fluorine-18-fluorodeoxyglucose; Drug-Resistant Epilepsy, Image Reconstruction.

Abstract

Purpose: In epilepsy pre-surgical evaluations, semi-automated quantitative analysis of Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) brain PET complements visual assessment for localizing the seizure onset zone. This study evaluates how adjusting reconstruction parameters enhances quantitative accuracy, aiming to identify optimal configurations for reliable clinical decision-making.

Materials and Methods: 234 reconstruction methods were applied to ¹⁸F-FDG brain PET images of a 47-year-old male with focal epilepsy. The parameters encompassed the 3D-Ordered-Subset Expectation Maximization image reconstruction method, both with Resolution Recovery (RR) and without (non-RR), various numbers of iterations×subset (#it×sub), pixel sizes, and Gaussian filters. The accuracy errors were determined by the Relative Difference Percentage (RDP) in measured maximum standardized uptake value SUV_max and absolute Z-scores from all 234 reconstructed images, compared to reference values from the normal database reconstruction set as the benchmark

Results: The study revealed that reconstructed images with 5 mm or 8 mm full width at half maximum (FWHM) Gaussian filters yielded RDP values above 5% for SUV_max and Z-scores, indicating potential inaccuracy with higher values of post-smoothing filters. The recommended reconstruction sets with RDP values below 5% for both RR and non-RR images were those with a 3 mm FWHM Gaussian filter and higher (#it×sub), specifically (5×21, 8×21), (5×21, 6×21), and (7×21, 8×21) for pixel sizes of 1.01 mm, 1.35 mm, and 2.03 mm, respectively.

Conclusion: The findings underscore the significant impact of altering the image reconstruction sets on the SUVmax and Z-scores. Furthermore, the inconsistent fluctuations of Z-scores emphasize the importance of using standardized image reconstruction sets to ensure accurate and reliable quantitative outcomes in epilepsy pre-surgical evaluations.