RT Journal Article
SR Electronic
T1 Role of 68Ga-fibroblast activation protein inhibitor (FAPI) PET/CT in the evaluation of peritoneal carcinomatosis and comparison with 18F-FDG PET/CT
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 20
OP 20
VO 62
IS supplement 1
A1 Haojun Chen
A1 Liang Zhao
A1 Yizhen Pang
A1 Long Sun
A1 Hua Wu
YR 2021
UL http://jnm.snmjournals.org/content/62/supplement_1/20.abstract
AB 20Purpose: Peritoneal carcinomatosis mainly refers to metastatic malignant spread to the peritoneum, mostly from gastric, colorectal, and ovarian cancers. The aim of this study was to explore the role of 68Ga-FAPI PET/CT, compared with 18F-fluorodeoxyglucose (18F-FDG) PET/CT, for evaluating peritoneal carcinomatosis in patients with various types of cancer. Methods: This is a post-hoc retrospective analysis of a sub-cohort of patients from a previously prospectively acquired database, namely the patient data screened in a study that was registered at ClinicalTrials.gov (NCT04416165) and was approved by the Institutional Clinical Research Ethics Committee. Patients with suspected peritoneal malignancy, who underwent both 18F-FDG and 68Ga-FAPI (DOTA-FAPI-04) PET/CT between October 2019 and August 2020, were retrospectively analysed. The radiotracer uptake, peritoneal cancer index (PCI) score, and diagnostic performance of 18F-FDG and 68Ga-FAPI PET/CT were evaluated and compared. Results: Our cohort consisted of 46 patients, including 16 patients with diffuse-type peritoneal carcinomatosis, 27 with nodular-type peritoneal carcinomatosis, and 3 true negative patients. A significant difference in standard uptake values (SUV) of lesions between 18F-FDG and 68Ga-FAPI PET/CT examination was observed (median SUV: 3.48 vs. 9.82; P < 0.001), particularly in peritoneal carcinomatosis from gastric cancer (median SUV: 3.44 vs. 8.05; P = 0.001). Peritoneal carcinomatosis was detected by 18F-FDG PET/CT in 31 of 43 patients, leading to a sensitivity of 72.09%, while the sensitivity of 68Ga-FAPI PET/CT for the diagnosis of peritoneal carcinomatosis was 97.67% (P = 0.002). Specifically, the diagnostic performance of 18F-FDG PET/CT was the worst in gastric cancer, with a sensitivity of 53.85% (7/13), compared with 100% (13/13) for 68Ga-FAPI PET/CT (P = 0.015). In addition, 18F-FDG PET/CT showed relatively lower sensitivity in colorectal cancer (71.43%) and pancreatic cancer (66.67%) than in 68Ga-FAPI PET/CT (100%). Moreover, the extent of lesions on 68Ga-FAPI PET/CT was significantly greater than that on 18F-FDG, which was reflected by the greater PCI score derived from 68Ga-FAPI PET/CT (median PCI, 16 vs. 32, P < 0.001). Lesion-by-lesion analysis was further performed in this patient group, with a total number of 124 nodular lesions evaluated (those lesions which were visible on the CT images and were confirmed by surgical exploration or radiographic follow-up). The median lesion size for the 124 lesions was 1.12 cm (range, 0.34‒3.67 cm). The 18F-FDG PET-positive lesions had mostly a large volume of disease (median, 1.64 cm; 0.74‒3.67 cm). In contrast, 18F-FDG PET-negative lesions demonstrated low-volume disease, and the peritoneal implants from these patients were relatively small, ranging from 0.34 to 3.42 cm (median 1.01 cm). Less than half of the nodular-type lesions (49/124) were detected by 18F-FDG PET, resulting in a sensitivity of 39.52%. Impressively, most of the nodular-type lesions (115/124) were detected by 68Ga-FAPI PET/CT, which yielded a significantly higher sensitivity (92.74%) than that of 18F-FDG PET/CT for the detection of nodular-type lesions (P < 0.001). Conclusions: 68Ga-FAPI PET/CT demonstrated superior sensitivity over 18F-FDG PET/CT for the detection of peritoneal carcinomatosis in patients with various types of cancer, particularly gastric cancer. Furthermore, the uptake of 68Ga-FAPI in peritoneal carcinomatosis was significantly higher than that of 18F-FDG, demonstrating a larger extent of the lesion and yielding a higher PCI score. This could help enhance the image contrast, improve physicians’ diagnostic confidence, and reduce the proportion of missed diagnoses.