Superiority of [(68)Ga]Ga-FAPI-04/[(18)F]FAPI-42 PET/CT to [(18)F]FDG PET/CT in delineating the primary tumor and peritoneal metastasis in initial gastric cancer.

This study aimed to compare [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT with [18F]FDG PET/CT in the evaluation of initial gastric cancer. We retrospectively compared [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT with [18F]FDG PET/CT in patients with initial gastric cancer from September 2020 to March 2021. Lesion detectability and the uptake of lesions quantified by the maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR) were compared between the two modalities using the Wilcoxon signed-rank test, Mann-Whitney U test, and McNemar's chi-square test. A total of 61 patients (37 males, aged 23-81 years) were included, of which 22 underwent radical gastrectomy. For primary lesions, higher uptake of [68Ga]Ga-FAPI-04/[18F]FAPI-42 was observed compared to [18F]FDG (median SUVmax, 14.60 vs 4.35, p < 0.001), resulting in higher positive detection using [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT than [18F]FDG PET/CT (95.1% vs 73.8%, p < 0.001), particularly for tumors with signet-ring cell carcinoma (SRCC) (96.4% vs 57.1%, p < 0.001). [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT detected more positive lymph nodes than [18F]FDG PET/CT (637 vs 407). However, both modalities underestimated N staging compared to pathological N staging. [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT showed a higher sensitivity (92.3% vs 53.8%, p = 0.002) and peritoneal cancer index score (18 vs 3, p < 0.001) in peritoneum metastasis and other suspect metastases compared to [18F]FDG PET/CT. Our findings indicate that [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT outperformed [18F]FDG PET/CT in the evaluation of primary tumors with SRCC and peritoneum metastasis in initial gastric cancer. However, no clinically useful improvement was seen in N staging. • The uptake of [68Ga]Ga-FAPI-04/[18F]FAPI-42 in primary tumor and metastasis was intensely higher than that of [18F]FDG (p < 0.001) in 61 patients with initial gastric cancer. • [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT had a higher sensitivity detection in primary tumors (95.1% vs 73.8%, p < 0.001) and peritoneal metastases (92.3% vs 53.8%, p = 0.002) than [18F]FDG PET/CT. • [68Ga]Ga-FAPI-04/[18F]FAPI-42 PET/CT depicted more positive lymph nodes than [18F]FDG PET/CT (637 vs 407); however, both underestimated N staging compared to pathological N staging.

Fu L ，Huang S ，Wu H ，Dong Y ，Xie F ，Wu R ，Zhou K ，Tang G ，Zhou W ... -  《-》

[(68)Ga]Ga-DOTA-FAPI-04 PET/CT in the evaluation of gastric cancer: comparison with [(18)F]FDG PET/CT.

This study aimed to compare the performance of [68Ga]Ga-DOTA-FAPI-04 and [18F]FDG PET/CT in the evaluation of primary and metastatic lesions of gastric cancer. Fifty-six patients with histologically proven gastric carcinomas were enrolled in this study, including 45 patients for staging and 11 patients for restaging after surgery. Each patient underwent both [18F]FDG and [68Ga]Ga-DOTA-FAPI-04 PET/CT within 1 week. The activity of tracer accumulation in lesions was assessed by maximum standardized uptake value (SUVmax) and TBR (lesions SUVmax/ascending aorta SUVmean). Histological workup served as a standard of reference. If tissue diagnosis was not applicable, the follow-up data including the results of laboratory tests and medical imaging could also serve as a reference. [68Ga]Ga-DOTA-FAPI-04 PET/CT was comparable to [18F]FDG on detecting primary tumors and lymph node (LN) metastases, whereas [68Ga]Ga-DOTA-FAPI-04 outperformed [18F]FDG in detecting peritoneal (159 vs. 47, P < 0.001) and bone metastases (64 vs. 55, P = 0.003) by the lesion-based analysis. [68Ga]Ga-DOTA-FAPI-04 showed higher SUVmax (10.3 vs. 8.1, P = 0.004) and TBR (11.6 vs. 5.8, P < 0.001) in primary tumor, and higher TBR in LN involvement (8.0 vs. 3.7, P < 0.001) and peritoneal metastases (8.1 vs. 3.2, P < 0.001), compared with [18F]FDG PET/CT. The specificity and positive predictive value of [68 Ga]Ga-DOTA-FAPI-04 were significantly higher than that of [18F]FDG (100.0% vs. 97.7%, P < 0.001; 100.0% vs. 57.1%, P = 0.001) in determining the LN status. [68Ga]Ga-DOTA-FAPI-04 was comparable to [18F]FDG in evaluating N-staging (47.1% vs. 23.5%, P = 0.282). [68Ga]Ga-DOTA-FAPI-04 PET/CT detected more positive recurrent lesions in all restaging patients and showed clearer tumor delineation. Two patients underwent follow-up [68Ga]Ga-DOTA-FAPI-04 PET/CT scans after chemotherapy, which both showed remission. [68Ga]Ga-DOTA-FAPI-04 PET/CT can better evaluate primary gastric cancer and metastatic lesions in the peritoneum, abdominal LNs, and bone. Furthermore, [68Ga]Ga-DOTA-FAPI-04 PET/CT provided more information for patients with recurrent disease and had the potential in monitoring response to treatment.

Lin R ，Lin Z ，Chen Z ，Zheng S ，Zhang J ，Zang J ，Miao W ... -  《-》

Comparison of [(68)Ga]Ga-FAPI and [(18)F]FDG uptake in patients with gastric signet-ring-cell carcinoma: a multicenter retrospective study.

In this study, we investigated the role of [68Ga]Ga-FAPI PET imaging in the detection of primary and metastatic gastric signet-ring-cell carcinoma (GSRCC) and compared with [18F]FDG PET. This retrospective multicenter analysis included 34 patients with histologically confirmed GSRCCs from four medical centers. The maximum standard uptake value (SUVmax), tumor-to-background ratio (TBR), and diagnostic accuracy were compared between the two modalities. [18F]FDG and [68Ga]Ga-FAPI uptakes were compared by using the Wilcoxon signed-rank test. McNemar's test was used to compare the diagnostic accuracy between the two techniques. Data were analyzed from 27 paired PET/CT and 7 paired PET/MRI scans for 34 GSRCC patients (16 men and 18 women) who had a median age of 51 years (range: 25-85 years). [68Ga]Ga-FAPI PET showed higher SUVmax and TBR values than did [18F]FDG PET in the primary tumors (SUVmax: 5.2 vs. 2.2, p = 0.001; TBR: 7.6 vs. 1.3, p < 0.001), involved lymph nodes (SUVmax: 6.8 vs. 2.5, p < 0.001; TBR: 5.8 vs. 1.3, p < 0.001), and bone and visceral metastases (SUVmax: 6.5 vs. 2.4, p < 0.001; TBR: 6.3 vs. 1.3, p < 0.001). In diagnostic performance, [68Ga]Ga-FAPI PET exhibited higher sensitivity than [18F]FDG PET for detecting primary tumors (73% [16/22] vs. 18% [4/22], p < 0.001), local recurrences (100% [7/7] vs. 29% [2/7], p = 0.071), lymph node metastases (77% [59/77] vs. 23% [18/77], p < 0.001), and distant metastases (93% [207/222] vs. 39% [86/222], p < 0.001). The results from this multicenter retrospective analysis justify the clinical use of [68Ga]Ga-FAPI tracers for GSRCC diagnosis and staging. • [68Ga]Ga-FAPI PET/CT is a promising imaging modality for the detection of primary and metastatic disease and has implications for TNM staging in GSRCC. • In this multicenter study of 34 patients with GSRCC, [68Ga]Ga-FAPI PET exhibited greater radiotracer uptake, tumor-to-background ratios, and diagnostic accuracy than [18F]FDG PET for detecting primary/recurrent tumors and metastatic lesions.

Chen H ，Pang Y ，Li J ，Kang F ，Xu W ，Meng T ，Shang Q ，Zhao J ，Guan Y ，Wu H ，Xie F ，Wang J ，Sun L ... -  《-》

(68)Ga-DOTA-FAPI-04 PET/MR in the Evaluation of Gastric Carcinomas: Comparison with (18)F-FDG PET/CT.

We sought to evaluate the performance of 68Ga-DOTA-FAPI-04 ( 68 Ga-FAPI) PET/MR for the diagnosis of primary tumor and metastatic lesions in patients with gastric carcinomas and to compare the results with those of 18F-FDG PET/CT. Methods: Twenty patients with histologically proven gastric carcinomas were recruited, and each patient underwent both 18F-FDG PET/CT and 68 Ga-FAPI PET/MR. A visual scoring system was established to compare the detectability of primary tumors and metastases in different organs or regions (the peritoneum, abdominal lymph nodes, supradiaphragmatic lymph nodes, liver, ovary, bone, and other tissues). The original SUVmax and normalized SUVmax (calculated by dividing a lesion's original SUVmax with the SUVmean of the descending aorta) of selected lesions on both 18F-FDG PET/CT and 68Ga-FAPI PET/MR were measured. Original/normalized SUVmax-FAPI and SUVmax-FDG were compared for patient-based (including a single lesion with the highest activity uptake in each organ/region) and lesion-based (including all lesions [≤5] or the 5 lesions with highest activity [>5]) analyses, respectively. Results: The 20 recruited patients (median age: 56.0 y; range: 29-70 y) included 9 men and 11 women, 14 patients for initial staging and 6 for recurrence detection. 68Ga-FAPI PET was superior to 18F-FDG PET for primary tumor detection (100.00% [14/14] vs. 71.43% [10/14]; P = 0.034), and the former had higher tracer uptake levels (P < 0.05). 68Ga-FAPI PET was superior to 18F-FDG PET in both patient-based and lesion-based evaluation except for the metastatic lesions in supradiaphragmatic lymph nodes and ovaries. Additionally, multiple sequences of MR images were beneficial for the interpretation of hepatic metastases in 3 patients, uterine and rectal metastases in 1 patient, ovarian lesions in 7 patients, and osseous metastases in 2 patients. Conclusion:68Ga-FAPI PET/MR outperformed 18F-FDG PET/CT in visualizing the primary and most metastatic lesions of gastric cancer and might be a promising method, with the potential of replacing 18F-FDG PET/CT.

Qin C ，Shao F ，Gai Y ，Liu Q ，Ruan W ，Liu F ，Hu F ，Lan X ... -  《-》

Usefulness of [(68)Ga]FAPI-04 and [(18)F]FDG PET/CT for the detection of primary tumour and metastatic lesions in gastrointestinal carcinoma: a comparative study.

To assess and compare the diagnostic performance of gallium-68-labelled fibroblast activation protein inhibitor ([68Ga]FAPI-04) and fluorine-18 fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) in gastrointestinal cancer. Fifty-one patients who underwent both [18F]FDG and [68Ga]FAPI-04 PET/CT for initial staging or restaging were enrolled. Histopathological findings, typical radiological appearances, and clinical imaging follow-up were used as the reference standard. The diagnostic performance of the two tracers was calculated and compared. The maximum standardised uptake value (SUVmax), mean SUV (SUVmean), tumour-to-mediastinal blood pool ratio (TBR), and tumour-to-liver ratio (TLR) of primary and metastatic lesions were measured and compared between two imaging modalities. In patient-based analysis, [68Ga]FAPI-04 showed much better diagnostic sensitivity than [18F]FDG in detecting primary tumour (94.44% [17/18] vs. 61.11% [11/18]), postoperative recurrence and metastases (95.65% [22/23] vs. 69.57% [16/23]), and peritoneal carcinomatosis (100% [28/28] vs. 60.71% [17/28]) (all p < 0.05). In lesion-based analysis, [68Ga]FAPI-04 showed higher sensitivity than [18F]FDG for detecting lymph node metastases. In peritoneal carcinomatosis, the median SUVmax (12.12 vs. 7.18) and SUVmean (6.84 vs. 4.11) with [68Ga]FAPI-04 were significantly higher than those with [18F]FDG (all p < 0.005). The TBR and TLR of [68Ga]FAPI-04 were significantly higher than those of [18F]FDG for detecting primary tumour, lymph node, liver, and peritoneal metastases (all p < 0.005). Therapeutic management changed in 13 patients according to [68Ga]FAPI-04 PET/CT compared with conventional imaging. [68Ga]FAPI-04 is superior to [18F]FDG PET/CT for detecting primary tumour, postoperative recurrence and metastasis, and peritoneal carcinomatosis in gastrointestinal cancer. • [68Ga]FAPI-04 PET/CT showed significantly higher sensitivity than [18F]FDG PET/CT in the detection of primary tumour and postoperative recurrence and metastasis in patients with gastrointestinal carcinoma. • [68Ga]FAPI-04 PET/CT had obvious advantages over [18F]FDG PET/CT in the detection of peritoneal carcinomatosis from gastrointestinal carcinoma with a much higher FAPI uptake value, TBR, and TLR. • Although the median SUVmax and SUVmean of [68Ga]FAPI-04 were similar to those of [18F]FDG for the primary tumour, lymph node metastases, and liver metastases in gastrointestinal carcinoma, the TBR and TLR of the SUVmax and SUVmean were significantly higher on [68Ga]FAPI-04 PET/CT, causing the lesions to be displayed more clearly.

Li C ，Tian Y ，Chen J ，Jiang Y ，Xue Z ，Xing D ，Wen B ，He Y ... -  《-》