Diagnostic value of [¹⁸F]AlF-NOTA-FAPI-04 PET/CT in breast cancer: comparison with conventional imaging

Conventional imaging has limitations in differentiating benign from malignant breast lesions and in staging breast cancer (BC). This study compared the diagnostic and staging performance of [¹⁸F]AlF-NOTA-FAPI-04 PET/CT with conventional imaging in suspected breast lesions.

This single-center post hoc retrospective analysis included therapy-naïve participants with suspected breast lesions who underwent [¹⁸F]AlF-NOTA-FAPI-04 PET/CT between July 2023 and February 2025. All patients underwent ultrasonography, mammography, breast MRI, whole-body CT, and bone scan. Conventional imaging results were based on consensus visual interpretation integrating these modalities. PET/CT images were assessed visually and semi-quantitatively to assess the diagnostic accuracy. Lesions were confirmed by histopathology and follow-up (median, 4.5 months). Diagnostic performance for primary breast lesions, regional lymph nodes metastases (LNM), and distant metastases was evaluated on lesion-based, whereas visual scoring and staging (the AJCC eighth edition) comparisons were patient-based. Receiver operating characteristic/Delong and McNemar χ² analyses were performed using SPSS Statistics 29.0. A two-sided P < 0.05 was statistically significant.

Sixty-nine women (median age, 50 years) with 81 breast lesions, 797 regional lymph nodes, and 94 distant metastases were included, and all 69 patients underwent ultrasonography, mammography, breast MRI, whole-body CT, and bone scan. For primary breast lesions, conventional imaging showed sensitivity and specificity of 93.75% and 100.00%, whereas visual PET/CT showed 98.44% and 70.59%. Although LBR_breast achieved the highest area under the curve (AUC), its AUC was not significantly different from that of conventional imaging (1.000 vs. 0.970, P = 0.078). In contrast, visual PET/CT showed a significantly lower AUC than conventional imaging (0.845 vs. 0.970, P = 0.034). For regional LNM detection, visual PET/CT achieved sensitivity and specificity of 95.95% and 97.60%, which were significantly higher than the corresponding values of conventional imaging (73.99% and 95.41%, all P < 0.05). PET/CT detected all 94 distant metastases, and patient-based visual scores favored PET/CT over conventional imaging (52 vs. 34). PET/CT also improved the accuracy in predicting pathological N staging (91.43% vs. 65.71%, P = 0.008) and final staging (74.29% vs. 45.71%, P = 0.009).

[¹⁸F]AlF-NOTA-FAPI-04 PET/CT outperforms conventional imaging in detecting regional LNM and improving pathological staging accuracy in BC.