Utilization of Gallium-68 Fibroblast Activation Protein Inhibitor Positron Emission Tomography (⁶⁸Ga-FAPI PET) for...

Background Head and neck cancers (HNCs) encompass a group of malignancies that arise in the mucosal surfaces of the oral cavity, pharynx, larynx, and other related structures. Advances in imaging modalities such as positron emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) have improved tumor detection and staging, aiding in personalized treatment approaches. PET-CT is used to diagnose and stage various cancers. Interpretation of neck masses can be quite challenging, particularly in the context of prior surgery and radiotherapy. A standardized lexicon and risk classification system for interpreting images in patients treated for HNC has been developed by the American College of Radiology (ACR) Neck Imaging Reporting and Data System (Ni-RADS) Committee. While fluorine-18 fluorodeoxyglucose (18F-FDG) PET-CT is widely used to assess head and neck malignancies, we have chosen to employ gallium-68 fibroblast activation protein inhibitor (⁶⁸Ga FAPI) PET-CT in the Ni-RADS category in this investigation because to its exclusive advantages over FDG. Methodology This was a non-funded retrospective-prospective study conducted in the Department of Radiodiagnosis at Healthcare Global Hospital, KR Road, Bangalore, following approval from the Institutional Ethical Committee. The period of observation for this study was January 2024 to June 2024. Patients with known HNC who were on follow-up and referred for a ⁶⁸Ga FAPI PET-CT scan were included in the study. The Ni-RADS score was assigned, and histopathological correlation was performed. Descriptive statistics were used, and sensitivity and specificity were calculated. Results Out of the 41 cases selected for the study, all Ni-RADS 1 cases (100%, 6/6) were nonmalignant. Among Ni-RADS 2 cases 3 (37.5%) were malignant and 5 (62.5%) were nonmalignant. Nearly all Ni-RADS 3 cases (26/27, 96.3%) were malignant, indicating that higher Ni-RADS scores strongly correlate with malignancy. Recurrence is significantly associated with a Ni-RADS 3 score, whereas nonmalignancy is associated with a lower score (P < 0.001). Similar results were also seen in the case of nodal recurrences. This study showed that ⁶⁸Ga FAPI PET-CT has a high sensitivity of 88.3% and specificity of 95.8% in identifying recurrent malignant and nonmalignant cases. Conclusions We can conclude that FAPI PET, which offers several advantages over FDG, can be effectively used in the Ni-RADS criteria for diagnosing HNC recurrences. The utilization of FAPI PET in conjunction with contrast-enhanced CT facilitates the identification of tumor morphological and metabolic features. However, further research and larger cohorts are needed to improve prediction accuracy and guide personalized treatment decisions.