Key points are not available for this paper at this time.
Background Accurate clinical staging is crucial to managing gastrointestinal cancer, but fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT has limitations. Targeting fibroblast-activation protein is a newer diagnostic approach for the visualization of tumor stroma, and gallium 68 (68Ga)-labeled fibroblast-activation protein inhibitors (FAPIs), hereafter 68Ga-FAPIs, present a promising alternative to 18F-FDG. Purpose To compare the diagnostic efficacy of 68Ga-FAPI PET/CT in primary and metastatic lesions of gastrointestinal malignancies with that of 18F-FDG PET/CT. Materials and Methods Images from patients with gastric, duodenal, and colorectal cancers who underwent contemporaneous 18F-FDG and 68Ga-FAPI PET/CT between October 2019 through June 2020 were retrospectively analyzed. 18F-FDG and 68Ga-FAPI uptakes were compared by using the Wilcoxon signed-rank test. The McNemar test was used to compare the diagnostic performance between the two techniques. Results Thirty-five patients (median age, 64 years interquartile range, 53-68 years; 18 men) were evaluated. In treatment-naive patients (n = 19), 68Ga-FAPI PET/CT led to upstaging of the clinical TNM stage in four (21%) patients compared with 18F-FDG PET/CT. Tracer uptake was higher with 68Ga-FAPI PET/CT than with 18F-FDG PET/CT in primary lesions (gastric cancer: 12.7 vs 3.7, respectively, P = .003; colorectal cancer: 15.9 vs 7.9, P = .03), involved lymph nodes (6.7 vs 2.4, P P P P P = .01). In addition, the sensitivity of 68Ga-FAPI PET/CT was higher than that of 18F-FDG PET/CT in the detection of primary tumors (100% 19 of 19 vs 53% 10 of 19, respectively; P = .004), lymph nodes (79% 22 of 28 vs 54% 15 of 28, P P < .001). Conclusion Gallium 68 fibroblast-activation protein inhibitor PET/CT was superior to fluorine 18 fluorodeoxyglucose PET/CT in the detection of primary and metastatic lesions in gastric, duodenal, and colorectal cancers, with higher tracer uptake in most primary and metastatic lesions. Published under a CC BY 4.0 license.
Pang et al. (Tue,) studied this question.