Image quality evaluation in a modern PET system: impact of new reconstructions methods and a radiomics approach

Gabriel Reynés-Llompart,Aida Sabaté-Llobera,Cristina Gámez-Cenzano,Elena Llinares-Tello,Josep M Martí-Climent

doi:10.1038/s41598-019-46937-8

Abstract

The present work investigates the influence of different biological and physical parameters on image quality (IQ) perception of the abdominal area in a modern PET scanner, using new reconstruction algorithms and testing the utility of a radiomics approach. Scans of 112 patients were retrospectively included. Images were reconstructed using both OSEM + PSF and BSRM methods, and IQ of the abdominal region was subjectively evaluated. First, 22 IQ related parameters were obtained (including count rate and biological or mixed parameters) and compared to the subjective IQ scores by means of correlations and logistic regression. Second, an additional set of radiomics features was extracted, and a model was constructed by means of an elastic-net regression. For the OSEM + PSF and especially for the BSRM reconstructions, IQ parameters presented only at best moderated correlations with the subjective IQ. None of the studied parameters presented a good predictive power for IQ, while a simple radiomics model increased the performance of the IQ prediction. These results suggest the necessity of changing the standard parameters to evaluate IQ, particularly when a BSRM algorithm is involved. Furthermore, it seems that a simple radiomics model can outperform the use of any single parameter to assess IQ.

Highlights

Positron emission tomography (PET) with 18F-2-fluoro-2-deoxy-D-glucose (FDG) has become a routine image procedure for the management of oncological patients
Some of the measurements could be considered as standard image quality (IQ) parameters, such as the variance, signal-to-noise ratio (SNR) or contrast-to-noise ratio (CNR) of a target region[3,4,5]
The measurement of the patient noise equivalent count rate (NECR) is a promising idea in order to predict IQ, providing a measure of the image count statistics corrected by the degrading scatter and random events

Summary

Introduction

Positron emission tomography (PET) with 18F-2-fluoro-2-deoxy-D-glucose (FDG) has become a routine image procedure for the management of oncological patients. Some of the measurements could be considered as standard IQ parameters, such as the variance, SNR or contrast-to-noise ratio (CNR) of a target region (commonly a lesion or part of the healthy liver when human beings are involved)[3,4,5]. These parameters are an objective measurement that allows automation, though there can lack a connection between them and how IQ is perceived by the physician in some defined tasks (e.g. organ definition). Qualitative tasks are difficult to automate, as they involve a subjective human assessment, and models are usually limited to lesion detectability and conspicuity[12,13]

Methods

Results

Conclusion