Bone Marrow Metastases From Gastric Adenocarcinoma on 68Ga-FAPI-04 PET/CT

The Complementary Role of 68 Ga-FAPI-04 PET/CT in a Case of Neuroblastoma

ABSTRACT

As a common and highly aggressive malignancy of childhood, more than half of neuroblastomas are metastatic at the time of presentation. Herein, we reported 68 Ga-FAPI-04 and 18 F-FDG PET/CT findings in a 13-year-old girl with undifferentiated neuroblastoma. FAPI PET/CT showed intense uptake in the bone and bone marrow metastases. The primary lesions presented with low FAPI uptake but moderate FDG uptake. Above findings suggested the potential of FAPI PET/CT in the imaging evaluation of neuroblastoma.

Incidental FAPI Localization in Benign Bone Lesions in a Case of Carcinoma Stomach

ABSTRACT

Recently developed radiolabeled FAPI (fibroblast-activation protein inhibitors) have attracted researcher's attention in diagnosing various tumors because of its high specificity and better tumor-to-background ratio. Increasing use of 68 Ga-FAPI PET/CT has resulted in reporting of incidental benign findings as well. We hereby present a case of suspected carcinoma stomach showing increased uptake in primary tumor in stomach as well as incidental uptake in benign subchondral cysts in bilateral shoulder joints and right hip joint on 68 Ga-FAPI PET CT scan.

Early Detection of Gastric Intramucosal Adenocarcinoma on 68Ga-FAPI PET/CT

ABSTRACT

18F-FDG PET/CT may sometimes not be an ideal imaging method for gastric adenocarcinoma. Because of the unstable physiological uptake of 18F-FDG in the gastrointestinal tract and muscles, it may interfere with the detection of lesions. We present a case of gastric intramucosal adenocarcinoma detected by 68Ga-FAPI PET/CT in a patient with nasopharyngeal carcinoma.

Current research topics in FAPI theranostics: a bibliometric analysis

PURPOSE

The study aimed to provide a comprehensive bibliometric overview of the current scientific publications on fibroblast activation protein inhibitor (FAPI) positron emission tomography imaging and radionuclide therapy.

METHODS

A PubMed search was performed to identify all MEDLINE-indexed publications on FAPI imaging and radionuclide therapy. The last update was performed on 31 May 2022. An online database of this literature was created, and hierarchical topic-related tags were subsequently assigned to all relevant studies. Frequency analysis was used to evaluate the distribution of the following characteristics: first author's country of origin, journal of publication, study design, imaging techniques and radiopharmaceutical used, histopathological correlation, the type of cancer, and benign disease/uptake types evaluated.

RESULTS

A total of 294 relevant publications on original studies were identified, consisting of 209 (71%) case reports/series and 85 cohort studies (29%). The majority of studies focused on imaging topics, predominantly comparing uptake on FAPI-PET/CT with 2-[¹⁸F]FDG-PET/CT, anatomical imaging, and/or histopathology results. 68% of studies focused on malignancies, with gastro-intestinal cancer, hepato-pancreato-biliary cancer, mixed cancers/metastases, lung cancer, sarcoma, head and neck cancer, and breast cancer being the most frequently reported. 42% of studies focused on benign disease categories, with cardiovascular, musculoskeletal, HPB, head and neck, and IgG4-related disease as most common categories. 16/294 (5%) studies focused on radionuclide therapy, with preliminary reports of acceptable toxicity profiles, tumour activity retention, and suggestion of disease control.

CONCLUSION

FAPI research is rapidly expanding from diagnostic studies in malignancies and benign diseases to the first reports of salvage radionuclide therapy. The research activity needs to shift now from low-level-of-evidence case reports and series to prospectively designed studies in homogenous patient groups to provide evidence on how and in which clinical situations FAPI theranostics can be of added value to clinical care. We have provided an overview of current research topics to build upon.

Comparison of Diagnostic Efficacy of [68Ga]Ga-FAPI-04 and [18F]FDG PET/CT for Staging and Restaging of Gastric Cancer

Purpose

This study aimed to compare the potential diagnostic efficacy of gallium68-fibroblast-activation protein inhibitor ([⁶⁸Ga]Ga-FAPI-04) and fluorine18-fluorodeoxyglucose ([¹⁸F]-FDG) positron emission tomography-computed tomography (PET/CT) for primary tumors, lymph nodes, and distant metastatic lesions of gastric cancer (GC), and to explore the effects of [⁶⁸Ga]Ga-FAPI-04 and [¹⁸F]-FDG on tumor staging and restaging in GC.

Methods

This single-center retrospective study (NCT2100044131) was conducted at the Affiliated Hospital of the Southwest Medical University between June 2020 and December 2021. Images of patients with GC who were pathologically confirmed and underwent contemporaneous [¹⁸F]-FDG and [⁶⁸Ga]Ga-FAPI-04 PET/CT within 1 week were analyzed. The diagnostic efficacy of [⁶⁸Ga]Ga-FAPI-04 PET/CT and [¹⁸F]-FDG PET/CT for TNM staging of GC was compared using McNemar test. The maximum standard uptake value (SUVmax) of each lesion in the two imaging types was compared using the Mann-Whitney U test.

Results

In total, 25 patients with GC (mean age, 56 ± 12 years) were evaluated. [⁶⁸Ga]Ga-FAPI-04 PET/CT exhibited higher sensitivity compared to [¹⁸F]-FDG PET/CT for detecting primary tumors (18/19 [94.74%] vs. 13/19 [68.42%], χ2 = 6.866, P < 0.01), lymph node metastasis (75/77 [97.40%] vs. 32/77 [41.56%], χ2 = 2.888, P =0.089), and distant metastases (275/283 [97.17%] vs. 122/283 [43.11%], χ2 = 11.858, P < 0.01). [⁶⁸Ga]Ga-FAPI-04 accumulation was significantly higher than that of [¹⁸F]FDG in tumors (median SUVmax, 10.28 vs 3.20; U=59.00, P < 0.01), lymph node metastasis metastases (median SUVmax, 9.20 vs 3.15; U=53.50, P < 0.01), and distant metastases (median SUVmax, 8.00 vs 4.20; U=200.00, P < 0.01). Compared to [¹⁸F]-FDG PET/CT, [⁶⁸Ga]Ga-FAPI-04 PET/CT resulted in new oncological findings in 14/25 patients and corrected tumor staging or restaging in 7/25 patients.

Conclusion

Our preliminary results regarding the impact of [⁶⁸Ga]Ga-FAPI-04 PET/CT on tumor staging highlight the potential of this approach for increasing the accuracy of GC diagnosis, which may facilitate treatment decision-making.