Predictive value of 18F-fluorodeoxyglucose PET/CT in histological grade of incidental colorectal adenoma.

BACKGROUND: 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/computed tomography (PET/CT) as an imaging modality for the whole body has shown its value in detecting incidental colorectal adenoma. In clinical practice, adenomatous polyps can be divided into three groups: low-grade intraepithelial neoplasia (LGIN), high-grade intraepithelial neoplasia (HGIN) and cancer, which can lead to different clinical management. However, the relationship between the 18F-FDG PET/CT SUVmax and the histological grade of adenomatous polyps is still not established, which is a challenging but valuable task. METHODS: This retrospective study included 255 patients with colorectal adenoma (CRA) or colorectal adenocarcinomas (AC) who had corresponding 18F-FDG uptake incidentally found on PET/CT. The correlations of SUVmax with pathological characteristics and tumor size were assessed. Neoplasms were divided into LGIN, HGIN, and AC according to histological grade. Receiver operating characteristic (ROC) analysis was applied to evaluate the predictive value of the SUVmax-only model and comprehensive models which were established with imaging and clinical predictors identified by univariate and multivariate analysis. RESULTS: The SUVmax was positively correlated with histological grades (r=0.529, P<0.001). Univariate and multivariate analysis showed that SUVmax was an independent risk factor among all groups except between HGIN and AC. The area under the curves (AUCs) of the comprehensive model for distinguishing between AC and adenoma, LGIN and HIGN, LGIN and AC, and HGIN and AC were 0.886, 0.780, 0.945, 0.733, respectively, which is statistically higher than the AUCs of the SUVmax-only model with 0.812, 0.733, 0.863, and 0.688, respectively. CONCLUSIONS: As an independent risk factor, SUVmax based on 18F-FDG PET/CT is highly associated with the histological grade of CRA. Thus, 18F-FDG PET/CT can serve as a noninvasive tool for precise diagnosis and assist in the preoperative formulation of treatment strategies for patients with incidental CRA.

Evaluation of recurrence risk for patients with stage I invasive lung adenocarcinoma manifesting as solid nodules based on 18F-FDG PET/CT, imaging signs, and clinicopathological features.

BACKGROUND: Stage I lung adenocarcinoma is a heterogeneous group. Previous studies have shown the prognostic evaluation value of PET/CT in this cohort; however, few studies focused on stage I invasive adenocarcinoma manifesting as solid nodules. This study aimed to evaluate the recurrence risk for patients with stage I invasive lung adenocarcinoma manifesting as solid nodules based on 18F-FDG PET/CT, CT imaging signs, and clinicopathological parameters. METHODS: We retrospectively enrolled 230 patients who underwent 18F-FDG PET/CT examination between January 2013 and July 2019. Metabolic parameters: maximum standard uptake value (SUVmax), mean standard uptake value, tumor metabolic volume (MTV), and total tumor glucose digestion were collected. Kaplan-Meier method was used to evaluate recurrence-free survival (RFS), and the multivariate Cox proportional hazards model was used to determine the independent risk factors associated with RFS. The time-dependent receiver operating characteristic curve (ROC) method was used to calculate the optimal cutoff value of metabolic parameters. RESULTS: The 5-year RFS rate for all patients was 71.7%. Multivariate Cox analysis revealed that the International Association for the Study of Lung Cancer Pathology Committee (IASLC) pathologic grade 3 [Hazard ratio (HR), 3.96; 95% Confidence interval (CI), 1.11-14.09], the presence of cavity sign (HR 5.38; 95% CI 2.23-12.96), SUVmax (HR 1.23; 95% CI 1.13-1.33), and MTV (HR 1.05; 95% CI 1.01-1.08) were potential independent prognostic factors for RFS. Patients with IASLC grade 3, the presence of cavity sign, SUVmax > 3.9, or MTV > 5.4 cm3 were classified as high risk, while others were classified as low risk. There was a significant difference in RFS between the high-risk and low-risk groups (HR 6.04; 95% CI 2.17-16.82, P < 0.001), and the 5-year RFS rate was 94.1% for the low-risk group and 61.3% for the high-risk group. CONCLUSIONS: We successfully evaluate the recurrence risk of patients with stage I invasive adenocarcinoma manifesting as solid nodules for the first time. The 5-year RFS rate in the high-risk group was significantly lower than in the low-risk group (61.3% vs. 94.1%). Our study may aid in optimizing therapeutic strategies and improving survival benefits for those patients.