Reliability of Quantitative 18F-FDG PET/CT Imaging Biomarkers for Classifying Early Response to Chemoradiotherapy in Patients With Locally Advanced Non–Small Cell Lung Cancer

Abstract

Purpose of the Report We evaluated the reliability of 18F-FDG PET imaging biomarkers to classify early response status across observers, scanners, and reconstruction algorithms in support of biologically adaptive radiation therapy for locally advanced non–small cell lung cancer. Patients and Methods Thirty-one patients with unresectable locally advanced non–small cell lung cancer were prospectively enrolled on a phase 2 trial (NCT02773238) and underwent 18F-FDG PET on GE Discovery STE (DSTE) or GE Discovery MI (DMI) PET/CT systems at baseline and during the third week external beam radiation therapy regimens. All PET scans were reconstructed using OSEM; GE-DMI scans were also reconstructed with BSREM-TOF (block sequential regularized expectation maximization reconstruction algorithm incorporating time of flight). Primary tumors were contoured by 3 observers using semiautomatic gradient-based segmentation. SUVmax, SUVmean, SUVpeak, MTV (metabolic tumor volume), and total lesion glycolysis were correlated with midtherapy multidisciplinary clinical response assessment. Dice similarity of contours and response classification areas under the curve were evaluated across observers, scanners, and reconstruction algorithms. LASSO logistic regression models were trained on DSTE PET patient data and independently tested on DMI PET patient data. Results Interobserver variability of PET contours was low for both OSEM and BSREM-TOF reconstructions; intraobserver variability between reconstructions was slightly higher. ΔSUVpeak was the most robust response predictor across observers and image reconstructions. LASSO models consistently selected ΔSUVpeak and ΔMTV as response predictors. Response classification models achieved high cross-validated performance on the DSTE cohort and more variable testing performance on the DMI cohort. Conclusions The variability FDG PET lesion contours and imaging biomarkers was relatively low across observers, scanners, and reconstructions. Objective midtreatment PET response assessment may lead to improved precision of biologically adaptive radiation therapy.

Multitask Learning Radiomics on Longitudinal Imaging to Predict Survival Outcomes following Risk-Adaptive Chemoradiation for Non-Small Cell Lung Cancer

“…Patients scanned on the GE Discovery STE (GE Healthcare, Waukesha, WI, USA) underwent acquisitions of 5 min per bed position while patients scanned on GE Discovery MI underwent acquisitions of 2.5 min per bed position due to differences in scanner sensitivity. PET ordered subset expectation maximization (OSEM) reconstruction parameters were harmonized between scanners to yield concordant quantitative images [ 53 ]. CT-based attenuation correction (CTAC) of the standardized uptake values (SUV) in quantitative PET was applied [ 54 ].…”

“…Metabolic tumor volume (MTV) contours were prospectively delineated at each time point under the FLARE-RT trial protocol using a commercially validated semi-automatic gradient-based segmentation tool in MIM (PET Edge, MIM Software, Cleveland, OH, USA) with consensus from a multidisciplinary team, including a board-certified radiation oncologist. MTV contours defined in this way improved repeatability compared to manual contouring and reduced sensitivity to image reconstruction compared to fixed threshold contouring [ 53 ]. MTV contours were then propagated to all co-registered images.…”

Adding predictive and diagnostic values of pulmonary ground-glass nodules on lung cancer via novel non-invasive tests

“…The technique has been utilized in discrimination of lung cancers and prediction of possible responsiveness to treatments. For instance, peak standardized uptake value (SUVpeak) has been reported to be utilized to predict early response for adaptive radiation in locally advanced non-small cell lung cancer ( 45 ). Recent advances in techniques have highlighted the utilization of PET-CT scanning to determine invasiveness of GGNs, and to predict probable response to certain interventions.…”

PET/CT en estadiaje y evaluación del tratamiento en cáncer de pulmón de células no pequeñas

“…Otros investigadores, como Horn y su equipo (38) , han encontrado la gran utilidad que puede tener un estudio de PET/CT realizado en los regímenes quimio-radioterapia, pues así sería posible encontrar áreas susceptibles de tratamiento, que no han respondido a la quimioterapia inicial. Reconocen que existen limitaciones y que aún se requieren los resultados de trabajos en curso en varios lugares del mundo.…”