The Sum of Tumour-to-Brain Ratios Improves the Accuracy of Diagnosing Gliomas Using 18F-FET PET.

Jacek Furtak,Aleksandra Harat,Rita Lopatto,Jonathan H Sherman,Tomasz Wisniewski,Bogdan Malkowski,Maciej Harat,Agnieszka Zyromska

doi:10.1371/journal.pone.0140917

Abstract

Gliomas are common brain tumours, but obtaining tissue for definitive diagnosis can be difficult. There is, therefore, interest in the use of non-invasive methods to diagnose and grade the disease. Although positron emission tomography (PET) with 18F-fluorethyltyrosine (18F-FET) can be used to differentiate between low-grade (LGG) and high-grade (HGG) gliomas, the optimal parameters to measure and their cut-points have yet to be established. We therefore assessed the value of single and dual time-point acquisition of 18F-FET PET parameters to differentiate between primary LGGs (n = 22) and HGGs (n = 24). PET examination was considered positive for glioma if the metabolic activity was 1.6-times higher than that of background (contralateral) brain, and maximum tissue-brain ratios (TBRmax) were calculated 10 and 60 min after isotope administration with their sums and differences calculated from individual time-point values. Using a threshold-based method, the overall sensitivity of PET was 97%. Several analysed parameters were significantly different between LGGs and HGGs. However, in a receiver operating characteristics analysis, TBR sum had the best diagnostic accuracy of 87% and sensitivity, specificity, and positive and negative predictive values of 100%, 72.7%, 80%, and 100%, respectively. 18F-FET PET is valuable for the non-invasive determination of glioma grade, especially when dual time-point metrics are used. TBR sum shows the greatest accuracy, sensitivity, and negative predictive value for tumour grade differentiation and is a simple method to implement. However, the cut-off may differ between institutions and calibration strategies would be useful.

Highlights

Gliomas account for 80% of all primary tumours of the central nervous system (CNS) and can be associated with poor clinical outcomes [1]
The current study assesses the value of both single and dual time-point acquisition of 18F-FET Positron emission tomography (PET) parameters to differentiate between primary low-grade gliomas (LGGs) and high-grade gliomas (HGGs) to improve 18F-FET PET reproducibility between different facilities
Consecutive patients diagnosed at our institution between February 2009 and December 2013 that met the following eligibility criteria were included: a suspicion of primary brain glioma based on routine magnetic resonance imaging (MRI), histopathological confirmation of the diagnosis, no previous treatment, preoperative 18F-FET PET, and subsequent surgery of at least subtotal resection conducted in the 12 months after PET

Summary

Introduction

Gliomas account for 80% of all primary tumours of the central nervous system (CNS) and can be associated with poor clinical outcomes [1]. Since about 50% of brain tumours cannot be totally removed and subjected to complete histological assessment [2], there is great interest in the development and use of non-invasive methods that accurately reveal the biological status of the disease. Such methods are extremely important for obtaining image-guided biopsies to provide tissue for histological diagnosis, especially since biopsy-based diagnosis differs from resection-based diagnosis in up to 50% of cases [2]. The current study assesses the value of both single and dual time-point acquisition of 18F-FET PET parameters to differentiate between primary low-grade gliomas (LGGs) and high-grade gliomas (HGGs) to improve 18F-FET PET reproducibility between different facilities

Methods

Results

Conclusion