Detectability of Al18F-NOTA-HER2-BCH PET for Nodal Metastases in Patients With HER2-Positive Breast Cancer.

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The aim of this study was to compare Al18F-NOTA-HER2-BCH and 18F-FDG for detecting nodal metastases in patients with HER2-positive breast cancer on PET/CT. In this retrospective study, 62 participants with HER2-positive breast cancer underwent both Al18F-NOTA-HER2-BCH and 18F-FDG PET/CT. Participants were pathologically confirmed as HER2-positive (IHC 3+ or IHC 2+ with gene amplification on FISH). Three independent readers visually assessed uptake of tracers on imaging. Furthermore, the diagnostic accuracy of nodal metastases was assessed using c-statistics. The lesion uptakes were quantified by SUVmax and target-to-background ratio (TBR) and compared using the general linear mixed model. The findings showed nodal metastases in 33 (53%) participants, including 45% only with regional nodal metastasis and 55% with nonregional nodal metastasis. On per-patient level, the sensitivity and specificity of Al18F-NOTA-HER2-BCH and 18F-FDG based on the majority reads were 0.97, 0.97, and 0.85, 0.77, respectively. Five participants were visualized only on Al18F-NOTA-HER2-BCH. Seven participants with high uptake only on 18F-FDG PET/CT were confirmed to be inflammatory uptake by pathological results and later imaging follow-up. On per-lesion level, Al18F-NOTA-HER2-BCH PET/CT detected more axillary (98.8% vs 70.2%), extra-axillary (100% vs 61.7%), and nonregional (99.1% vs 67.0%) lymph nodal metastases than 18F-FDG PET/CT. Additionally, Al18F-NOTA-HER2-BCH PET/CT detected more nodal metastases small than 10 mm than 18F-FDG PET/CT (198 vs 125, 99.5% vs 62.8%). The median SUVmax and TBR of regional or nonregional nodal metastases at Al18F-NOTA-HER2-BCH were all higher than those on 18F-FDG (range of median SUVmax, 8.0-11.4 vs 2.3-5.6; P range, <0.001-0.007; range of median TBR, 7.3-16.3 vs 2.9-5.3; P range, <0.001). No adverse reactions related to imaging agents were observed in all participants. Al18F-NOTA-HER2-BCH PET/CT detected more regional and nonregional lymph nodal metastases in patients with HER2-positive breast cancer than on 18F-FDG PET/CT, especially for lesions small than 10 mm.