Are staging F-18-FDG PET/MRI radiomic features associated with metastases in cancer of the gastro-esophageal junction?

Purpose: To identify quantitative imaging biomarkers at staging F-18-Fluorodeoxyglucose (FDG)-positron-emission-tomography/magnetic-resonance-imaging (PET/MRI) for predicting distant metastasis in patients with gastro-esophageal junction(GEJ) cancer. Materials and Methods: Following IRB approval and informed consent, 24 patients with histologically proven GEJ cancer were prospectively recruited; 4 patients were excluded for technical reasons. Finally, 19 male and 1 female (68.3\ub19.1 years) were considered. Patients were injected with 326\ub128 MBq FDG intravenously. Uptake time was 90 minutes. Two experienced radiologists and nuclear physicians reviewed the images in consensus. Maximum standardized uptake value (SUVmax) and tumor size were analyzed. First-order and second-order statistical texture features were computed on SUV values of the whole tumor volume. k-means clustering algorithm was used to assess the correlation of feature-pairs with the presence of distant metastases. Sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV) and accuracy (ACC) were calculated to quantify the discrimination ability of features. Results: Second-order entropy and maximum probability, linked to texture irregularity and homogeneity respectively, were the best feature-pair in discriminating patients with and without metastatic disease (SE=80%, SP=70%, PPV=73%, NPV=78%, ACC=75%). SUVmax (SE=80%, SP=30%, PPV=53%, NPV=60%, ACC=55%) and tumor size (SE=90%, SP=10%, PPV=50%, NPV=50%, ACC=50%) performed worse, particularly for specificity. Conclusions: These results confirm the common expectation that greater intra-tumor heterogeneity correlates with metastatic potential. The extraction of advanced quantitative PET imaging features from the primary lesion may help prognostication. Clinical Relevance statement: Radiomics may help in improving prognostication at staging

18F-FDG PET/MRI versus PET/CT in staging Gastro-Esophageal Junction cancer

Purpose: To compare F-18-Flurodeoxyglucose(FDG)-positron-emission-tomography/magnetic-resonance-imaging(PET/MRI) and PET/computed-tomography(PET/CT) in staging of gastro-esophageal junction(GEJ) cancer. Materials and Methods: Following IRB approval and informed consent, 24 patients with histologically proven GEJ cancer were prospectively recruited; 4 patients were excluded for technical reasons (19 male, 1 female; mean 68.3 +/- 9.1 years). Patients were injected with 326+/-28 MBq F-18-FDG intravenously for the clinical PET/CT. Uptake time was 60 minutes. PET/MRI was acquired directly after the PET/CT. 2 experienced radiologists and nuclear physicians reviewed the images and defined the PET/MRI-TNM stage in consensus. PET/CT NM-stage was defined clinically. They were compared to the multidisciplinary team meeting(MDT) stage, which was defined by contrast enhanced CT+/-endoscopic ultrasonography(EUS). Sensitivity(SE), Specificity(SP), positive predictive value(PPV), negative predictive value(NPV) and accuracy(AC) were calculated. McNemar test was performed to assess differences between different modalities. Results: For PET/MRI T-stage was concurred with MDT stage in 14 (70%) of 20 patients. Differences in T-stages between PET/MRI and MDT were statistically significant (p=0.03) (Table1). In our cohort, PET/MRI upstaged three T3 primary lesions as T4 and correctly assigned two T4 lesions. Both PET/MRI and PET/CT agreed in N-and M-staging in all patients. Differences in N-stage between hybrid modalities and MDT were significant (p=0.03) (6 of 20 patients) (Table2). SE, SP, PPV, NPV and AC for detection of lymph node metastases were 94%, 100%, 100%, 67% and 95% for both imaging modalities. Conclusions: PET/MRI and PET/CT performed similarly in N and M staging. PET/MRI has advantages over PET/CT in providing additional T-stage. Clinical Relevance statement: PET/MRI might be used for staging of patients with cancer of GOJ in the future. Table 1: Differences in T-stage. PET/MRI MDT 3 4 4 3 2 3 4 3 4 3 2 3 4 4 Table 2: Differences in N-stage. PET/MRI PET/MRI MDT 2 2 1 0 0 1 2 2 1 2 2 3 2 2 3 1 1

Exploratory radiomic features from integrated ¹⁸F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging are associated with contemporaneous metastases in oesophageal/gastroesophageal cancer

PURPOSE The purpose of this study was to determine if 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) features are associated with contemporaneous metastases in patients with oesophageal/gastroesophageal cancer. METHODS Following IRB approval and informed consent, patients underwent a staging PET/MRI following 18F-FDG injection (326 ± 28 MBq) and 156 ± 23 min uptake time. First-order histogram and second-order grey level co-occurrence matrix features were computed for PET standardized uptake value (SUV) and MRI T1-W, T2-W, diffusion weighted (DWI) and apparent diffusion coefficient (ADC) images for the whole tumour volume. K-means clustering assessed the correlation of feature-pairs with metastases. Multivariate analysis of variance (MANOVA) was performed to assess the statistical separability of the groups identified by feature-pairs. Sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy (ACC) were calculated for these features and compared with SUVmax, ADCmean and maximum diameter alone for predicting contemporaneous metastases. RESULTS Twenty patients (18 males, 2 female; median 67 years, range 52-86) comprised the final study cohort; ten patients had metastases. Lower second-order SUV entropy combined with higher second-order ADC entropy were the best feature-pair for discriminating metastatic patients, MANOVA p value <0.001 (SN = 80%, SP = 80%, PPV = 80%, NPV = 80%, ACC = 80%). SUVmax (SN = 30%, SP = 80%, PPV = 60%, NPV = 53%, ACC = 55%), ADCmean (SN = 20%, SP = 70%, PPV = 40%, NPV = 47%, ACC = 45%) and tumour maximum diameter (SN = 10%, SP = 90%, PPV = 50%, NPV = 50%, ACC = 50%) had poorer sensitivity and accuracy. CONCLUSION High ADC entropy combined with low SUV entropy is associated with a higher prevalence of metastases and a promising initial signature for future study