Utility of preoperative [¹⁸F]FDG PET/CT for CT-guided biopsy planning of large tumors: target adjustment and malignant yield with hotspot targeting

Abstract

Objective

To assess the clinical utility of preoperative [¹⁸F]FDG PET/CT for CT-guided biopsy planning of large tumors, including predictors of PET/CT-informed target adjustment and malignant yield with FDG hotspot targeting in very large tumors.

Methods

In this retrospective single-center study (January 2015–December 2025), we analyzed 82 patients who underwent pre-biopsy [¹⁸F]FDG PET/CT at our institution within 90 days. Target adjustment was retrospectively adjudicated as the presence of a spatial difference between the contrast-enhanced CT-based target and the PET/CT-informed target selected after considering intratumoral FDG uptake. ROC analysis was used to evaluate whether tumor size predicted target adjustment and to determine the optimal cutoff. Multivariable logistic regression included age, sex, tumor size, PET system (analog vs. digital), ΔSUV, lesion location (chest vs. other), and lymphoma (vs. other). In tumors ≥ 52 mm, malignant yield was compared between hotspot (highest uptake) and non-hotspot targeting.

Results

Target adjustment was performed in 28/82 cases (34.1%). Interobserver agreement was 89% with Cohen’s κ = 0.74 (95% CI, 0.58–0.89). Tumor size predicted target adjustment (AUC 0.847; 95% CI 0.761–0.934), and the Youden-optimal cutoff was 52 mm (sensitivity 0.82, specificity 0.81). Target adjustment rates were 5/49 (10.2%) for < 52 mm and 23/33 (69.7%) for ≥ 52 mm (p < 0.001). In multivariable analysis, tumor size (per 10 mm) was independently associated with target adjustment (OR 2.33; 95% CI 1.56–3.50; p < 0.001), while female sex was inversely associated (OR 0.20; 95% CI 0.04–0.96; p = 0.045). Lymphoma showed a trend toward an inverse association that did not reach statistical significance (OR 0.11; 95% CI 0.01–1.11; p = 0.062). The multivariable model showed good discrimination (AUC 0.90; 95% CI 0.82–0.98; DeLong). Among tumors ≥ 52 mm, malignant pathology was obtained in 14/14 cases (100%) with hotspot targeting versus 5/9 (55.6%) with non-hotspot targeting (p = 0.014).

Conclusions

Preoperative [¹⁸F]FDG PET/CT supports CT-guided biopsy planning of large tumors by identifying cases likely to require target adjustment and was associated with higher malignant yield when the FDG hotspot was targeted in tumors ≥ 52 mm.