Recent studies have shown the potential of fibroblast activating protein inhibitor (FAPI) PET imaging for pancreatic cancer assessment. This article is dedicated to comparing the diagnostic efficacy of FAPI PET and [18F]fluorodeoxyglucose (FDG) PET in the evaluation of primary tumors, lymph nodes, and distant metastases in pancreatic cancer. In this review, we conducted a systematic search of studies published in PubMed and Web of Science databases up to September 18, 2023. All included studies used radionuclide labeled FAPI and FDG as PET diagnostic tracers to evaluate their applicability in patients with pancreatic cancer. The FAPI PET imaging group showed significantly higher sensitivity in the detection of primary lesions (1.000, [95

ABSTRACT:A 67-year-old woman presented with dysphagia for 2 months. Enhanced chest CT suggested thickening of the esophageal wall, which was suspected to be a malignancy. The patient then underwent 18 F-FDG and 68 Ga-FAPI PET/CT. Increased uptake was observed in both tracers in the thickened esophageal wall. However, biopsy demonstrated candida infection of esophagus. After treatment, the symptoms of the patient were relieved.

This study aimed to explore the feasibility of [68 Ga]pentixafor positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma (NPC). This prospective study included patients with NPC who underwent [68 Ga]pentixafor PET/CT and 2-[18F]fuoro-2-deoxy-D-glucose ([18F]FDG) PET/CT within one week between November 2022 and March 2023. The [68 Ga]pentixafor and [18F]FDG uptakes in primary and metastatic lesions were measured and compared. Twenty-five participants (21 patients for initial stage and four patients for recurrence detection) were enrolled in our study. The participants underwent [18F]FDG PET/CT and [68 Ga]pentixafor PET/CT. [68 Ga]pentixafor PET/CT had the same detection rate as [18F]FDG for primary tumor (96

Abstract A 2-and-a-half-year-old boy with a previous history of Langerhans cell histiocytosis reached remission as assessed by 18F-FDG PET/CT. Routine follow-up 18F-FDG PET/CT revealed the appearance of new bone lesions in the right scapula and right ischium with abnormal FDG activity 3 months after the end of treatment, and Langerhans cell histiocytosis recurrence was considered. Meanwhile, these lesions also showed increased FAPI uptake. After adjusting the chemotherapy regimen, both FDG and FAPI uptake almost disappeared in these lesions.

ABSTRACT:A 57-year-old woman without hepatitis B or immunodeficiency presented with right upper abdominal pain and cough for 3 months. CT revealed one nodule in the lung and another in the liver. Both 18 F-FDG and 68 Ga-FAPI PET/CT showed increased tracer uptake in these 2 nodules, suggesting pulmonary carcinoma with hepatic metastasis. Finally, biopsies of these 2 nodules demonstrated the diagnoses of hepatic adenocarcinoma and pulmonary cryptococcosis. This case highlights that cryptococcosis can be FAPI-avid.

PURPOSE:[18F]FDG PET/CT to detect unknown primary lesions is essential for clinical management but still has limitations. [68Ga]Ga-FAPI is a tumor-stromal imaging agent that provides a promising alternative to [18F]FDG for the assessment of malignancies. We aimed to investigate whether [68Ga]Ga-FAPI PET/CT has an additional role in identifying unknown primary lesions with negative or equivocal [18F] FDG PET/CT results.METHODS:This single-center prospective clinical study was conducted between March 2020 and March 2022 at Southwest Medical University Hospital. Patients underwent [18F]FDG PET/CT for the identification of unknown primary lesions. They underwent repeat [68Ga]Ga-FAPI PET/CT when [18F]FDG PET/CT results were negative or equivocal. Histopathological examination, surgery, or clinical follow-up (at least 3 months) for FAPI-positive lesions. The diagnostic efficacy of [68Ga]Ga-FAPI in identifying unknown primary lesions was evaluated.RESULTS:A total of 44 participants (median age, 57 ± 12 [SD]; 22 [50%] men) were evaluated. Thirteen of the 44 patients had equivocal [18F]FDG PET/CT findings, while the diagnosis was clear on [68Ga]Ga-FAPI PET/CT. [68Ga]Ga-FAPI PET/CT also revealed primary lesions in additional 17 patients with negative [18F]FDG PET/CT findings. In fourteen of 44 patients, no primary lesion was detected by either tracer. On this basis, we analyzed 94 lymph node metastatic lesions. The mean SUVmax of lymph node metastases on [68Ga] Ga-FAPI PET/CT and [18F]FDG PET/CT were 9.2 ± 5.1, 7.9 ± 4.8 (p = 0.03) and the mean TBR were 9.1 ± 5.2, 4.9 ± 3.1 (p < 0.01), respectively.CONCLUSION:[68Ga]Ga-FAPI PET/CT showed great potential for identifying unknown primary lesions and has the potential to improve the detection rate of unknown primary lesions with negative or equivocal for [18F]FDG findings.TRIAL REGISTRATION:ClinicalTrial.gov. Identifier: ChiCTR2100044131.

Abstract A 57-year-old woman without hepatitis B or immunodeficiency presented with right upper abdominal pain and cough for 3 months. CT revealed one nodule in the lung and another in the liver. Both 18F-FDG and 68Ga-FAPI PET/CT showed increased tracer uptake in these 2 nodules, suggesting pulmonary carcinoma with hepatic metastasis. Finally, biopsies of these 2 nodules demonstrated the diagnoses of hepatic adenocarcinoma and pulmonary cryptococcosis. This case highlights that cryptococcosis can be FAPI-avid.

Purpose We aimed to compare the potential value of 68Ga-FAPI-04 and 18F-FDG PET/CT in primary cervical cancer and lymph node metastases. Methods Patients with cervical cancer underwent both 68Ga-FAPI-04 and 18F-FDG PET/CT. Histopathology and follow-up CT or MRI results (at least 3 months of follow-up) were used as reference criteria. Paired-sample t test was used to compare the SUVmax of 18F-FDG and 68Ga-FAPI-04 PET/CT for cervical cancer primary lesions and metastatic lymph nodes. Results A total of 35 patients with a mean age of 53 ± 11 years (range, 30–76 years) were included. The detection rate of both tracers for primary tumors was 100%. There was no significant correlation between 18F-FDG and 68Ga-FAPI-04 for SUVmax (14.5 ± 5.7 vs 15.1 ± 6.2; P = 0.645). In addition, the detection rates of 68Ga-FAPI-04 and 18F-FDG for lymph node metastasis were 100% and 98%, respectively. No significant difference was found in SUVmax between 18F-FDG and 68Ga-FAPI-04 groups (7.6 ± 4.0 vs 7.0 ± 3.5; P = 0.572). Twelve false-positive lymph nodes were detected in 8 patients with 18F-FDG PET/CT, none of which were developed on 68Ga-FAPI-04 PET/CT. Conclusion 68Ga-FAPI-04 PET/CT has a high tracer rate for the diagnosis of primary cervical cancer and lymph node metastases. Moreover, 68Ga-FAPI-04 PET/CT also showed good results in distinguishing metastatic lymph nodes from reactive lymph nodes of cervical cancer.

ABSTRACT:An 84-year-old man with prostate cancer with neuroendocrine differentiation underwent PET/CT for staging. 68 Ga-prostate-specific membrane antigen PET/CT did not show significant abnormal tracer accumulation, whereas 18 F-OC ( 18 F-AlF-NOTA-octreotide) PET/CT showed elevated tracer uptake at multiple sites throughout the body. Therefore, the patient opted to receive 1 cycle of 177 Lu-DOTATATE peptide receptor radionuclide therapy with a dose of 200 mCi. Encouragingly, radiographic tumor remission and improvement of clinical symptoms were observed after only 1 cycle of treatment.

Objectives: Although FAPI, as a pan-tumor tracer, shows high expression in the malignancy imaging, FAPI uptake is also seen in some benign lesions. The purpose of this study was to retrospectively analyze the characteristics of benign lesions with FAPI uptake on 68Ga-FAPI PET/CT imaging. Methods: The electronic medical and imaging records of patients undergoing 68Ga-FAPI PET/CT imaging in the Department of Nuclear Medicine of our hospital from March 2020 to March 2022 were retrospectively analyzed. Patients with benign lesions confirmed by histopathological analysis or long-term follow-up of FAPI-positive lesions were included in the study. Results: A total of 44 patients (i.e., 44 benign lesions) were included in this study, including 14 women and 30 men, ranging in age from 19 to 74 years. Benign lesions involved eight systems, including liver (n = 3), tail of pancreas (n = 3), stomach (n = 3), esophagus (n = 1), lung (n = 14), and mediastinum (n = 2), sinuses (n = 1), brain (n = 2), lymph nodes (n = 5), kidneys (n = 4), bones (n = 2), muscles (n = 1), thyroid (n = 1), parathyroid gland (n = 1), and breast (n = 1). The mean SUVmax (p = 0.471) and mean TBR (p = 0.830) of benign lesions in the eight systems were not significantly different. Conclusion: Our studies have shown that in addition to malignant tumors, certain benign lesions also show uptake of FAPI, and it is necessary for doctors to distinguish these benign lesions from true malignant tumors. Advances in knowledge: Benign lesions may also show FAPI expression, which may make the differential diagnosis of benign and malignant lesions difficult and should be alerted by physicians.