Relationships between histogram analysis of ADC values and complex 18F-FDG-PET parameters in head and neck squamous cell carcinoma.

Hans-Jonas Meyer,Sandra Purz,Alexey Surov,Osama Sabri,Kewei Chen

doi:10.1371/journal.pone.0202897

Abstract

PurposeHistogram analysis is an emergent imaging technique to further analyze radiological images and to obtain imaging biomarker. In head and neck cancer, MRI and PET are routinely used in clinical practice. The aim of this study was to analyze associations between histogram based ADC parameters and complex FDG-PET derived parameters in head and neck squamous cell carcinoma (HNSCC).Methods34 patients (26% female, mean age, 56.7 ± 10.2 years) with primary HNSCC were prospectively included into the study. ADC histogram parameters were calculated by inhouse made matlab software using a whole lesion measurement. For each tumor, maximum and mean standardized uptake values (SUVmax, SUVmean), Total Lesion Glycolysis (TLG) and Metabolic Tumor Volume (MTV) were determined on PET-images. Spearman's correlation coefficient (ρ) was used to analyze associations between investigated parameters. Benjamini-Hochberg correction was used to adjust for multiple testing. Mann-Whitney test was used for group discrimination. P-values < 0.05 were taken to indicate statistical significance.ResultsThe correlation analysis in the whole tumor group revealed a statistically significant correlation between entropy and MTV as well as TLG (ρ = 0.67, P<0.0001 and ρ = 0.61, P = 0.0002 respectively).There were statistically significant differences between T1/2 and T3/4 tumors in the following parameters: entropy (2.07 ± 0.36 vs 2.61 ± 0.43, P = 0.007), SUVmax (10.79 ± 4.13 vs 17.93 ± 5.89, P = 0.007), SUVmean (6.39 ± 2.48 vs 9.81 ± 4.49, P = 0.01), SUVmin (4.09 ± 1.57 vs 6.34 ± 2.59, P = 0.03), MTV (9.50 ± 7.92 vs 20.36 ± 13.30, P = 0.02), TGU (55.97 ± 39.09 vs 212.3 ± 186.3, P = 0.002).ConclusionThis study showed that entropy derived from ADC maps is strongly associated with MTV and TLG in HNSCC. Entropy, SUVmax, SUVmean, TLG and MTV were statistically significant higher in T3/4 tumors in comparison to T1/2 carcinomas.

Highlights

Head and neck squamous cell carcinoma (HNSCC) is one of the most frequent malignancies [1]
This study showed that entropy derived from apparent diffusion coefficient (ADC) maps is strongly associated with Metabolic Tumor Volume (MTV) and Total Lesion Glycolysis (TLG) in HNSCC
Various studies identified an inverse relationship between ADC values and cellularity as well proliferation index indicating that ADC values reflect tumor microstructure [3, 4]

Summary

Introduction

Head and neck squamous cell carcinoma (HNSCC) is one of the most frequent malignancies [1]. Different imaging modalities like computed tomography (CT) and magnetic resonance tomography (MRI) are used for correct tumor staging in HNSCC [2]. Functional imaging modalities, such as diffusion-weighted imaging (DWI) can be added into imaging protocol to provide further insight into tumor microstructure [2]. DWI measures random water movement and can be quantified by the apparent diffusion coefficient (ADC) [3]. A novel approach, namely histogram analysis of different images, was proposed [7]. For this technique, every voxel of a region of interest is used to issue a histogram and gain more data regarding tumor [7]. Thereby, a broad spectrum of ADC parameters can be estimated: ADC percentiles, mode ADC, median ADC, kurtosis, skewness, and entropy [7]

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Conclusion