Abstract
PurposeWe compared attenuation correction of PET images with helical CT (PET/HCT) and respiration-averaged CT (PET/ACT) in patients with non-small-cell lung cancer (NSCLC) with the goal of investigating the impact of respiration-averaged CT on 18F FDG PET texture parameters.Materials and MethodsA total of 56 patients were enrolled. Tumors were segmented on pretreatment PET images using the adaptive threshold. Twelve different texture parameters were computed: standard uptake value (SUV) entropy, uniformity, entropy, dissimilarity, homogeneity, coarseness, busyness, contrast, complexity, grey-level nonuniformity, zone-size nonuniformity, and high grey-level large zone emphasis. Comparisons of PET/HCT and PET/ACT were performed using Wilcoxon signed-rank tests, intraclass correlation coefficients, and Bland-Altman analysis. Receiver operating characteristic (ROC) curves as well as univariate and multivariate Cox regression analyses were used to identify the parameters significantly associated with disease-specific survival (DSS). A fixed threshold at 45% of the maximum SUV (T45) was used for validation.ResultsSUV maximum and total lesion glycolysis (TLG) were significantly higher in PET/ACT. However, texture parameters obtained with PET/ACT and PET/HCT showed a high degree of agreement. The lowest levels of variation between the two modalities were observed for SUV entropy (9.7%) and entropy (9.8%). SUV entropy, entropy, and coarseness from both PET/ACT and PET/HCT were significantly associated with DSS. Validation analyses using T45 confirmed the usefulness of SUV entropy and entropy in both PET/HCT and PET/ACT for the prediction of DSS, but only coarseness from PET/ACT achieved the statistical significance threshold.ConclusionsOur results indicate that 1) texture parameters from PET/ACT are clinically useful in the prediction of survival in NSCLC patients and 2) SUV entropy and entropy are robust to attenuation correction methods.
Highlights
Despite significant advances in targeted therapy [1], the prognosis of patients with non-small cell lung cancer (NSCLC) remains dismal. 18F-FDG PET imaging plays an essential role in the diagnosis and staging of NSCLC
Texture parameters obtained with PET/averaged CT (ACT) and PET images with helical CT (PET/helical CT (HCT)) showed a high degree of agreement
PET/ACT and PET/HCT were significantly associated with disease-specific survival (DSS)
Summary
Despite significant advances in targeted therapy [1], the prognosis of patients with non-small cell lung cancer (NSCLC) remains dismal. 18F-FDG PET imaging plays an essential role in the diagnosis and staging of NSCLC. The mining of a large number of quantitative image features has been referred to “radiomics” and holds promise as a method for identifying specific prognostic signatures [10, 21,22,23,24,25,26] In this scenario, accurate and reproducible measurements of texture features are essential for clinical use. The temporal difference between PET and CT introduces misalignment artifacts in PET images To address this issue, attenuation correction of PET images with respiration averaged CT (ACT) has been utilized. We designed the current study to compare attenuation correction of PET images with HCT and ACT in NSCLC with the goal of investigating the impact of respiration-averaged CT on FDG PET texture parameters
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