Interim Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography to Predict Pathologic Response to Preoperative Chemoradiotherapy and Prognosis in Patients With Locally Advanced Rectal Cancer.

INTRODUCTION: The goal of the present study was to investigate the predictive and prognostic values of interim fluorine-18 (18F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) parameters for the prediction of a complete pathologic response (pCR) in patients with locally advanced rectal cancer (LARC) who had received preoperative chemoradiotherapy (PCRT). PATIENTS AND METHODS: A total 103 patients with LARC were included in the present study. All the patients were evaluated by 18F FDG PET/CT before and after 45 Gy of radiotherapy with concurrent oral capecitabine chemotherapy. The quantitative, volumetric parameters and their percentage of change (Δ%) were used to predict the pCR and calculate the overall survival (OS). The predictive value for a pCR of 18F FDG PET/CT cutoff values were determined by receiver operating characteristic analysis. The prognostic significance was assessed using Kaplan-Meier analysis. RESULTS: A pCR occurred in 22 patients (21.4%). Univariate and multivariate analyses demonstrated that the post-PCRT maximum standardized uptake value (SUVmax2) and change in the SUVmax (ΔSUVmax) as significant factors for the prediction of pCR, with a sensitivity of 68.2% and specificity of 87.7% and sensitivity of 90.9% and specificity of 80.3%, respectively. Kaplan-Meier analysis showed that a low SUVmax2 (< 2.5) and high ΔSUVmax (≥ 62.2%) were potent predictors for OS. CONCLUSION: The present study has shown the capability of interim 18F FDG PET/CT parameters to predict the achievement of pCR after PCRT in patients with LARC. Of the parameters, SUVmax2 and ΔSUVmax were potent predictors for pCR and well associated with OS.

Initial Experience of 18F-FDG PET/MRI in Thymic Epithelial Tumors: Morphologic, Functional, and Metabolic Biomarkers.

PURPOSE: The aim of this study was to investigate the value of morphologic, functional, and metabolic biomarkers acquired concurrently at PET/MRI in patients with thymic epithelial tumors. PATIENTS AND METHODS: During 1 year, 9 patients with suspected thymic epithelial tumors at contrast-enhanced chest CT were prospectively enrolled and underwent preoperative 18F-FDG PET/MRI. Two chest radiologists prospectively reviewed the CT and MRI scans of PET/MRI in consensus, and 2 nuclear physicians reviewed the PET images. Visual assessment of the tumor morphology, functional biomarkers such as apparent diffusion coefficient from diffusion-weighted images, and metabolic biomarkers (including SUVmax, metabolic tumor volume, total lesion glycolysis, and heterogeneity index) were recorded. All patients underwent operation, and their pathologic reports served as the reference standard. RESULTS: Thymic epithelial tumors were demonstrated in all 9 patients at pathologic examination. Tumor contour (P = 0.012) and shape (P = 0.033) had an association with the World Health Organization subtype, and the presence of septum (P = 0.048) on MRI scans had an association with the Masaoka stage. In terms of functional and metabolic biomarkers, SUVmax (ρ = 0.683, P = 0.042) and SUV/apparent diffusion coefficient (ρ = 0.703, P = 0.035) correlated with the Masaoka stage. Metabolic tumor volume (P = 0.024), heterogeneity index (P = 0.024), and total lesion glycolysis (P = 0.048) were useful for classification between low- and high-risk thymic epithelial tumors. CONCLUSIONS: Although limited by the small number of patients enrolled, morphologic, functional, and metabolic biomarkers derived from PET/MRI scans were useful for the stratification of thymic epithelial tumors.

Volumetric parameters changes of sequential 18F-FDG PET/CT for early prediction of recurrence and death in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy.

UNLABELLED: : The goal of the present study was to determine whether volumetric parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured by sequential F-FDG PET/CT imaging could be used as prognostic factors in patients with locally advanced rectal cancer (LARC) who received preoperative concurrent chemoradiotherapy. METHODS: A total 64 patients with LARC patients were included in the current study. All patients were evaluated by F-FDG PET/CT before and after 45 Gy of radiotherapy with concurrent oral capecitabine chemotherapy. Initial, second, and the percent changes ([INCREMENT], %) of semiquantitative and volumetric parameters were used to calculate recurrence-free survival (RFS) and overall survival (OS). The cutoff values of semiquantitative and volumetric parameters were determined by receiver operating characteristic curve analysis. The prognostic significance was assessed using univariate and multivariate Cox proportional hazard regression analysis. RESULTS: For RFS, American Joint Committee on Cancer (AJCC) stage (χ = 10.7, P = 0.002), surgical margin (+) (χ = 3.39, P = 0.037), lymphatic invasion (+) (χ = 6.8, P = 0.0078), RECIST (Response Evaluation Criteria in Solid Tumors) (χ = 46.3, P < 0.0001), SUVmax1 (χ = 10.1, P = 0.025), ΔSUVmax (χ = 20.4, P < 0.0001), ΔSUVmean (χ = 28.8, P < 0.0001), MTV1 (χ = 24.1, P < 0.0001), ΔMTV (χ = 27.4, P < 0.0001), TLG1 (χ = 21.9, P < 0.0001), TLG2 (χ = 23.3, P < 0.0001), and ΔTLG (χ = 55.6, P < 0.0001) are associated prognostic factors. For OS, AJCC stage (χ = 6.0, P = 0.021), surgical margin (+) (χ = 3.2, P = 0.042), lymphatic invasion (+) (χ = 3.8, P = 0.048), RECIST (χ = 10.4, P = 0.0015), ΔSUVmax (χ = 6.0, P = 0.013), ΔSUVmean (χ = 10.5, P = 0.0009), MTV1 (χ = 14.5, P = 0.0008), ΔMTV (χ = 14.7, P = 0.0002), TLG1 (χ = 15.8, P = 0.0002), TLG2 (χ = 13.5, P = 0.0006), and ΔTLG (χ = 17.5, P < 0.0001) are potent predictors. Multivariate Cox proportional hazard regression analyses revealed that the initial MTV (MTV1) and ΔTLG were the potent predictors for RFS and OS. CONCLUSIONS: Our data suggest that MTV on initial pretreatment F-FDG PET/CT and ΔTLG of sequential F-FDG PET/CT after preoperative concurrent chemoradiotherapy in LARC patients could provide prognostic information.