Comparative Study\nof [<sup>18</sup>F]AlF-LNC1007,\n[<sup>18</sup>F]FDG, and [<sup>18</sup>F]AlF-NOTA-FAPI-04 PET/CT in Breast Cancer Diagnosis: A Methodological\nExploration and Analytical Insight

<b>Objective:</b> To compare the diagnostic value\nof [<sup>18</sup>F]AlF-LNC1007, [<sup>18</sup>F]FDG, and [<sup>18</sup>F]AlF-NOTA-FAPI-04\nPET/CT in breast cancer. <b>Methods:</b> 33 patients with highly\nsuspected or already diagnosed but untreated breast cancer were enrolled\nin the study and underwent [<sup>18</sup>F]AlF-LNC1007 (30 patients),\n[<sup>18</sup>F]FDG (22 patients), and [<sup>18</sup>F]AlF-NOTA-FAPI-04\n(8 patients) PET/CT. Quantitative measurements included the SUV<sub>max</sub> and tumor-to-background ratio (TBR) for all lesions and\nbackground tissues. The Chi-square test was used for intergroup diagnostic\nefficacy, and the Wilcoxon test was used for intergroup SUV<sub>max</sub> or TBR. Diagnostic efficacy for lymph node metastasis was evaluated\nusing receiver operating characteristic (ROC) analysis. <b>Results:</b> Compared to [<sup>18</sup>F]FDG, [<sup>18</sup>F]AlF-LNC1007 had\na higher positive predictive value (100% vs 91%, <i>P</i> = 0.0004) in lymph node metastases (42 vs 46) and higher sensitivity\n(100 vs 76%, <i>P</i> = 0.0003) in bone metastases (33 vs\n25) but lower sensitivity (93 vs 100%, <i>P</i> = 0.001)\nin liver metastases. Apart from liver metastases, [<sup>18</sup>F]AlF-LNC1007\nPET/CT had higher SUV<sub>max</sub> in primary tumor and other metastases,\nwith no statistical difference in TBR. Compared to [<sup>18</sup>F]AlF-NOTA-FAPI-04\nPET/CT, [<sup>18</sup>F]AlF-LNC1007 had less false-positive and a\nhigher positive predictive value in bone metastases (99 vs 95%, <i>P</i> = 0.0003) but had lower SUV<sub>max</sub>(<i>P</i> < 0.01) in all primary and metastases lesions. The TBR difference\nbetween [<sup>18</sup>F]AlF-LNC1007 and [<sup>18</sup>F]AlF-NOTA-FAPI-04\nwas statistically significant only in bone metastases (5.97 vs 5.02, <i>P</i> = 0.001). The comparison of lymph node detection efficacy\nbetween [<sup>18</sup>F]AlF-LNC1007 and [<sup>18</sup>F]FDG PET/CT\nshowed significant differences in SUV<sub>max</sub> cutoff values\nfor diagnosing lymph node metastases (2.62 vs 3.90), sensitivity (95.2%\nvs 66.67), and specificity (100% vs 85.00) (all <i>P</i> < 0.001). <b>Conclusion:</b> [<sup>18</sup>F]AlF-LNC1007\ndemonstrated superior efficacy compared to [<sup>18</sup>F]FDG and\n[<sup>18</sup>F]AlF-NOTA-FAPI-04 and higher uptake than [<sup>18</sup>F]FDG in primary tumor, lymph node and bone metastases, and higher\nTBR than [<sup>18</sup>F]AlF-NOTA-FAPI-04, especially in bone metastases.\n[<sup>18</sup>F]AlF-LNC1007 also showed high specificity in differentiating\ninflammatory and metastatic lymph nodes.