Inter-observer and segmentation method variability of textural analysis in pre-therapeutic FDG PET/CT in head and neck cancer.

Catherine Guezennec,Fanny Orlhac,Ulrike Schick,David Bourhis,Yves Gobel,Jean-Baptiste Corre,Pierre-Yves Salaün,Olivier Delcroix,Philippe Robin,Ronan Abgral

doi:10.1371/journal.pone.0214299

Abstract

AimCharacterizing tumor heterogeneity with textural indices extracted from 18F-fluorodeoxyglucose positron emission tomography (FDG PET/CT) is of growing interest in oncology. Several series showed promising results to predict survival in patients with head and neck squamous cell carcinoma (HNSCC), analyzing various tumor segmentation methods and textural indices. This preliminary study aimed at assessing the inter-observer and inter-segmentation method variability of textural indices in HNSCC pre-therapeutic FDG PET/CT.Materials and methodsConsecutive patients with HNSCC referred in our department for a pre-therapeutic FDG PET/CT from January to March 2016 were retrospectively included. Two nuclear medicine physicians separately segmented all tumors using 3 different segmentation methods: a relative standardized uptake value (SUV) threshold (40%SUVmax), a signal-to-noise adaptive SUV threshold (DAISNE) and an image gradient-based method (PET-EDGE). SUV and metabolic tumor volume were recorded. Thirty-one textural indices were calculated using LIFEx software (www.lifexsoft.org). After correlation analysis, selected indices’ inter-segmentation method and inter-observer variability were calculated.ResultsForty-three patients (mean age 63.8±9.3y) were analyzed. Due to a too small segmented tumor volume of interest, textural analysis could not be performed in 6, 11 and 15 cases with respectively DAISNE, 40%SUVmax and PET-EDGE segmentation methods. Five independent textural indices were selected (Homogeneity, Correlation, Entropy, Busyness and LZLGE). There was a high inter-contouring method variability for Homogeneity, Correlation, Entropy and LZLGE (p<0.0001 for each index). The inter-observer reproducibility analysis revealed an excellent agreement for 3 indices (Homogeneity, Correlation and Entropy) with an intraclass correlation coefficient higher than 0.90 for the 3 methods.ConclusionsThis preliminary study showed a high variability of 4 out of 5 textural indices (Homogeneity, Correlation, Entropy and LZLGE) extracted from pre-therapeutic FDG PET/CT in HNSCC using 3 different contouring methods. However, for each method, there was an excellent agreement between observers for 3 of these textural indices (Homogeneity, Correlation and Entropy).

Highlights

Solid malignancies usually show high levels of biologic heterogeneity, in terms of hypoxic and necrotic regions, variability in cellular proliferation and intra-tumoral angiogenesis
Consecutive patients with head and neck squamous cell carcinoma (HNSCC) referred in our department for a pre-therapeutic FDG PET/CT from January to March 2016 were retrospectively included
Taking this heterogeneity into account could help improve patients’ therapeutic management, classifying patients between different risk subgroups [1][2][3]. This could be useful in head and neck squamous cell carcinoma (HNSCC) which typically presents a high biologic heterogeneity [4][5][6]

Summary

Introduction

Solid malignancies usually show high levels of biologic heterogeneity, in terms of hypoxic and necrotic regions, variability in cellular proliferation and intra-tumoral angiogenesis. Taking this heterogeneity into account could help improve patients’ therapeutic management, classifying patients between different risk subgroups [1][2][3]. This could be useful in head and neck squamous cell carcinoma (HNSCC) which typically presents a high biologic heterogeneity [4][5][6]. Predicting tumor response to therapy remains difficult and could benefit from heterogeneity analysis

Methods

Results

Conclusion