Utility of Volumetric Metabolic Parameters on Preoperative FDG PET/CT for Predicting Tumor Lymphovascular Invasion in Non–Small Cell Lung Cancer

BACKGROUND. Lymphovascular invasion (LVI) is an adverse prognostic indicator in non-small cell lung cancer (NSCLC) and serves as an indication for postoperative adjuvant chemotherapy recommendation after resection. OBJECTIVE. The purpose of this article was to assess the utility of clinicopathologic factors and volumetric metabolic parameters from preoperative FDG PET/CT in predicting primary tumor LVI in NSCLC. METHODS. This retrospective study included 161 patients (mean age, 61.8 ± 8.1 [SD] years; 111 men, 50 women) with surgically confirmed NSCLC who underwent preoperative FDG PET/CT between January 2018 and November 2020. Two nuclear medicine physicians used software to place automated volumes of interest delineating each tumor to record metabolic indexes (SUV_max', SUV_mean', and metabolic tumor volume [MTV]), which in turn were used to calculate total lesion glycolysis (TLG). Measurements were first performed independently to determine interobserver agreement using intraclass correlation coefficients (ICCs) and then repeated in consensus. Associations of clinicopathologic and metabolic parameters with tumor LVI status were assessed using t test, Mann-Whitney U test, and chi-square test. Diagnostic performance was assessed using ROC analysis. Multivariable logistic regression analysis was performed to identify independent predictors of tumor LVI. RESULTS. A total of 23.6% (38/161) of patients had LVI. The ICCs were 1.000 for SUV_max', 0.997 for SUV_mean', and 0.999 for MTV. Tumors with LVI, compared with tumors without LVI, exhibited higher SUV_max (15.4 ± 5.9 vs 11.7 ± 7.5; p = .006), SUV_mean (6.0 ± 1.6 vs 5.1 ± 2.0; p = .009), MTV (median, 15.8 cm³ vs 5.5 cm³; p < .001), and TLG (median, 88.8 vs 24.5; p < .001). Among the metabolic parameters, AUC was highest for MTV (0.704), with an optimal MTV cutoff of 6.4 cm³ yielding sensitivity of 92.1% (35/38), specificity of 56.1% (69/123), PPV of 39.3% (35/89), and NPV of 95.8% (69/72) for LVI. Independent predictors (p < .05) of LVI were MTV (≥ 6.4 cm³; odds ratio [OR], 6.5), category N1 (OR, 6.4) or N2 (OR, 4.0) disease, and category T2 disease (OR, 3.6). These factors combined achieved AUC of 0.854 for LVI. CONCLUSION. The volumetric metabolic parameter MTV from preoperative FDG PET/CT is an independent predictor of tumor LVI in NSCLC. CLINICAL IMPACT. Further studies are warranted to assess the potential role of preoperative prediction of LVI using FDG PET/CT to help guide clinical decision making in NSCLC.