[¹⁸F]F-FAPI PET/CT is superior to [¹⁸F]F-FDG PET/CT for lymph node staging in lung cancer: a pathologically validated...

Area of Science:

• Oncology
• Radiology
• Nuclear Medicine

Background:

• Accurate lymph node staging is crucial for effective lung cancer treatment planning.
• Current imaging modalities like fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) have limitations in differentiating metastatic from benign lymph nodes.
• Fibroblast activation protein inhibitor (FAPI) PET/CT presents a potential alternative for improved diagnostic accuracy.

Purpose of the Study:

• To evaluate the diagnostic efficacy of [¹⁸F]F-FAPI PET/CT compared to [¹⁸F]F-FDG PET/CT for lung cancer lymph node staging.
• To determine the sensitivity, specificity, accuracy, and predictive values of FAPI PET/CT against histopathology.
• To assess the potential of FAPI PET/CT to reduce unnecessary invasive staging procedures.

Main Methods:

• A cohort of 32 lung cancer patients with FDG-positive lymph nodes was included.
• [¹⁸F]F-FAPI PET/CT was performed, followed by pathological confirmation of 71 lymph nodes via surgery or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).
• Diagnostic performance metrics, including SUVmax and TBR, were analyzed and compared between FAPI and FDG PET/CT.

Main Results:

• Metastatic lymph nodes exhibited significantly higher FAPI uptake (SUVmax: 13.6 ± 9.6) than benign nodes (SUVmax: 2.7 ± 1.9) (p < 0.001).
• [¹⁸F]F-FAPI PET/CT demonstrated superior diagnostic performance with a higher area under the curve (AUC 0.98) compared to [¹⁸F]F-FDG PET/CT (AUC 0.78) (p < 0.001).
• FAPI PET/CT achieved higher sensitivity (100% vs. 100%), specificity (91.7% vs. 16.7%), accuracy (97.0% vs. 43.9%), PPV (85.2% vs. 36.5%), and NPV (100% vs. 100%) than FDG PET/CT, leading to improved staging accuracy (93.8% vs. 43.8%) and downstaging in 15 patients.

Conclusions:

• [¹⁸F]F-FAPI PET/CT is a highly promising imaging modality for accurate lung cancer lymph node staging.
• FAPI PET/CT offers significantly higher specificity and a lower false-positive rate compared to FDG PET/CT.
• This advanced imaging technique has the potential to optimize invasive staging strategies and avoid unnecessary procedures like EBUS-TBNA.