Head-to-Head Comparison of [68Ga]Ga-FAPI-04 and [18F]-FDG PET/CT in Evaluating the Extent of Disease in Gastric Adenocarcinoma

Abstract

Background[18F]-Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) may sometimes be suboptimal for imaging gastric adenocarcinoma. The recently introduced [68Ga]Ga-FAPI-04 (FAPI) PET/CT targets tumor stroma and has shown considerable potential in evaluating the extent of disease in a variety of tumors.MethodsWe performed a head-to-head prospective comparison of FAPI and FDG PET/CT in the same group of 13 patients with gastric adenocarcinoma who presented for either initial staging (n = 10) or restaging (n = 3) of disease. Lesion detection and maximum standardized uptake value (SUVmax) were compared between the two types of radiotracers.ResultsAll ten primary gastric tumors were FAPI-positive (100% detection rate), whereas only five were also FDG-positive (50%). SUVmax was not significantly different, but the tumor-to-background ratio was higher for FAPI (mean, median, and range of 4.5, 3.2, and 0.8-9.7 for FDG and 12.9, 11.9, and 2.2-23.9 for FAPI, P = 0.007). The level of detection of regional lymph node involvement was comparable. FAPI showed a superior detection rate for peritoneal carcinomatosis (100% vs. none). Two patients with widespread peritoneal carcinomatosis underwent a follow-up FAPI scan after chemotherapy: one showed partial remission and the other showed progressive disease.ConclusionsThe findings of this study suggest that FAPI PET/CT outperforms FDG PET/CT in detecting both primary gastric adenocarcinoma and peritoneal carcinomatosis from gastric cancer. FAPI PET/CT also shows promise for monitoring response to treatment in patients with peritoneal carcinomatosis from gastric cancer, however, larger trials are needed to validate these findings.

68Ga-FAPI-04 PET for surveillance of anastomotic recurrence in postoperative patients with gastrointestinal cancer: a comparative study with 18F-FDG PET

“…Generally, the 68 Ga-FAPI-04 distribution at anastomotic sites was positively correlated with ¹⁸F-FDG and exhibited better imaging contrast than ¹⁸F-FDG, which is consistent with a previous finding for the detection of primary gastric cancer [12,24]. It has been reported that ¹⁸F-FDG PET SUVmax at anastomotic sites did not decrease over time in postoperative gastric cancer patients [6], and a similar pattern was observed in our study.…”

“…In preoperative patients, 68 Ga-FAPI-04 PET/CT imaging has recently been reported to have excellent performance in the diagnosis of primary gastrointestinal cancer (100% [10/10], [14/14], [19/19], [38/38]) compared to ¹⁸F-FDG PET/CT imaging (50.0-82.0%) [9,11,12,24], and also in detecting peritoneal carcinomatosis (100.0-97.7% vs. 0.0-72.1%) [10,24]. In this postoperative surveillance study, we discovered that the overall diagnostic performance of 68 Ga-FAPI-04 PET was better than ¹⁸F-FDG PET.…”

A 68Ga-FAPI-46 PET/CT Imaging Pitfall in Assessing Residual Gastric Cancer Early After Chemotherapy

“…In the resectate from patient B, only signs of fibrosis and inflammation were found (ypT0N0). As a radiotracer, the FAPI has shown promising results for the detection and staging of various kinds of cancers, especially in those less suitable for evaluation with 18 F-FDG PET/CT such as gastrointestinal malignancies 1–5 . Because of elevated FAPI uptake in tissues affected by inflammatory processes including fibrotic remodeling, 6 FAPI PET/CT may also be an asset in the evaluation of nononcological conditions such as cardiac ischemic injury 7,8 and IgG4-related disease 9 .…”

“…As a radiotracer, the FAPI has shown promising results for the detection and staging of various kinds of cancers, especially in those less suitable for evaluation with 18 F-FDG PET/CT such as gastrointestinal malignancies. [1][2][3][4][5] Because of elevated FAPI uptake in tissues affected by inflammatory processes including fibrotic remodeling, 6 FAPI PET/CT may also be an asset in the evaluation of nononcological conditions such as cardiac ischemic injury 7,8 and IgG4-related disease. 9 Concurrently, the non-malignancy-related FAPI uptake in degenerative processes, inflammation and in wound healing, 10 may cause difficulties when interpreting FAPI PET/CT in cancer patients.…”

Chronic Gastritis Mimicking Malignancy on 68Ga-FAPI-04 PET/CT

“…PET/CT imaging has been performed in various malignancy using FAP inhibitors (FAPIs) 2,3 . Recent studies have demonstrated that 68 Ga-FAPI-04 PET/CT has a superior detection rate than 18 F-FDG PET/CT for gastric cancer 4,5 . Also, FAPI uptake has been reported in nonmalignant diseases because of the chronic inflammation-induced transformation of fibroblasts to CAFs 6–9 .…”