Performance of fibroblast activating protein inhibitor PET imaging for pancreatic neoplasms assessment: a systematic review and meta-analysis.

BACKGROUND: Recent studies have shown the potential of fibroblast activating protein inhibitor (FAPI) PET imaging for pancreatic cancer assessment. PURPOSE: 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. METHODS: 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. RESULTS: The FAPI PET imaging group showed significantly higher sensitivity in the detection of primary lesions (1.000, [95% CI: 0.999-1.000]), lymph node metastases (0.624 [95% CI: 0.391-0.834]) and distant metastatic (0.965 [95% CI: 0.804-1.000]) in pancreatic cancer compared to the FDG PET imaging group (0.889 [95% CI: 0.788-0.966], 0.373 [95% CI: 0.163-0.606] and 0.889 [95% CI: 0.689-0.999], respectively). Furthermore, the maximum standardized uptake value (SUVmax) in FAPI PET imaging is significantly higher than that in FDG imaging for primary lesions (mean difference (MD) = 7.51, 95% CI: 5.34-9.67). CONCLUSION: Compared with [18F]FDG PET/CT, FAPI PET imaging showed higher sensitivity, SUVmax. This method can be effectively utilized for the evaluation of pancreatic cancer. CLINICAL RELEVANCE STATEMENT: Fibroblast activating protein inhibitor PET may be a better alternative to [18F]FDG in evaluating primary pancreatic cancer, lymph node metastases, and distant metastases. KEY POINTS: Fibroblast activating protein inhibitor (FAPI) PET is compared with FDG PET for evaluating pancreatic cancer. Multiple radiolabeled FAPI variants have shown promising results in the diagnosis of pancreatic cancer. FAPI PET imaging effectively helps clinicians diagnose and stage pancreatic cancer.

Comparison of [18F]FDG and [68 Ga]pentixafor PET/CT in Nasopharyngeal Carcinoma.

PURPOSE: This study aimed to explore the feasibility of [68 Ga]pentixafor positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma (NPC). PROCEDURES: 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. RESULTS: 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% vs. 96%). The [68 Ga]pentixafor maximum standard uptake value (SUVmax) and target-to-background ratio (TBR) of primary tumors were lower than those of [18F]FDG (SUVmax: 8.13 ± 2.78 vs. 14.25 ± 6.45; P < 0.01; TBR: 5.17 ± 2.14 vs. 9.81 ± 5.30, P < 0.01). The difference between tumor volume of [68 Ga]pentixafor (TVpentixafor) and tumor volume of [18F]FDG (TVFDG) showed no significance (median: 16.01 vs. 9.56, P = 0.332). In the detection of suspected metastatic cervical lymph nodes (CLNs), [68 Ga]pentixafor PET possessed a lower SUVmax than [18F]FDG PET/CT (SUVmax: 6.86 ± 2.63 vs. 10.39 ± 5.28, P < 0.01), but there was no significant difference in the detection rate between [68 Ga]pentixafor and [18F]FDG PET/CT (96 vs. 98, P = 0.613). CONCLUSIONS: [68 Ga]pentixafor is a promising imaging tracer for detecting primary and metastatic NPC. [68 Ga]pentixafor PET/CT is comparable to [18F]FDG PET/CT in the detection rate of primary tumors and metastatic cervical lymph nodes in nasopharyngeal carcinoma, but [68 Ga]pentixafor uptake was heterogeneous. [68 Ga]pentixafor PET/CT may help select patients most likely to benefit from CXCR4-directed endoradiotherapy. CLINICAL TRIAL REGISTRATION NO: ChiCTR2200065902.

MALT Lymphoma in Histologic Transformation: FDG-Avid but Pentixafor-Negative.

ABSTRACT: An 81-year-old woman experienced compression symptoms due to diffuse enlargement of the thyroid gland. The cytopathological results of thyroid fine-needle suggested malignancy. Therefore, she underwent bilateral thyroidectomy. Postoperative pathology indicated mucosa-associated lymphoid tissue (MALT) lymphoma. Three months later, she found a progressively enlarged mass in her neck. The biopsy showed MALT lymphoma with highly aggressive B-cell lymphoma transformation. 18F-FDG PET/CT showed increased metabolism in multiple lymph nodes. However, some of these lymph nodes were negative in 68Ga-pentxafor PET/CT. Our case demonstrated that 68Ga-pentixafor may have limited value in evaluating MALT lymphoma transformation.

68 Ga-FAPI and 18 F-FDG Uptake in a Patient With Esophageal Candida Infection.

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.

Head-to-Head Comparison of 18 F-FDG and 68 Ga-FAPI-04 PET/CT for Radiological Evaluation of Cervical Cancer.

PURPOSE: We aimed to compare the potential value of 68 Ga-FAPI-04 and 18 F-FDG PET/CT in primary cervical cancer and lymph node metastases. METHODS: Patients with cervical cancer underwent both 68 Ga-FAPI-04 and 18 F-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 SUV max of 18 F-FDG and 68 Ga-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 18 F-FDG and 68 Ga-FAPI-04 for SUV max (14.5 ± 5.7 vs 15.1 ± 6.2; P = 0.645). In addition, the detection rates of 68 Ga-FAPI-04 and 18 F-FDG for lymph node metastasis were 100% and 98%, respectively. No significant difference was found in SUV max between 18 F-FDG and 68 Ga-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 18 F-FDG PET/CT, none of which were developed on 68 Ga-FAPI-04 PET/CT. CONCLUSION: 68 Ga-FAPI-04 PET/CT has a high tracer rate for the diagnosis of primary cervical cancer and lymph node metastases. Moreover, 68 Ga-FAPI-04 PET/CT also showed good results in distinguishing metastatic lymph nodes from reactive lymph nodes of cervical cancer.

177 Lu-DOTATATE Therapy in a Case of Castrate-Resistant Prostate Cancer With Neuroendocrine Differentiation.

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.

FDG-Avid But Pentixafor-Negative in EBV-Associated T-Cell Lymphoproliferative Disorders.

ABSTRACT: An 18-year-old woman with intermittent fever, pancytopenia, abnormal liver function, and enlarged lymph nodes and hepatosplenomegaly was clinically suspected as hemophagocytic lymphohistiocytosis. 18 F-FDG PET/CT showed increased metabolism in multiple lymph nodes, which were highly suggestive of lymphoma. No increased CXCR4 expression in lymph nodes was demonstrated on 68 Ga-pentixafor PET/CT. Subsequent right neck lymph node biopsy pathology revealed EBV-associated lymphoproliferative disorders. Our case shows that 68 Ga-pentixafor PET/CT may have potential value in differentiating EBV-associated lymphoproliferative disorders from lymphomas.

The additional role of [68Ga]Ga-FAPI-04 PET/CT in patients with unknown primary lesion with a negative or equivocal [18F]FDG.

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.

Benign lesions with 68Ga-FAPI uptake: a retrospective study.

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.

Similar Findings on 68 Ga-Pentixafor PET/CT and 18 F-FDG PET/CT in a Patient With Widespread Metastatic Hepatic Neuroendocrine Carcinoma.

ABSTRACT: A patient with suspected malignant tumor underwent 18 F-FDG PET/CT. Based on the findings, the patient was suspected of having multiple myeloma. Then the patient underwent 68 Ga-pentixafor PET/CT, which showed similar results to 18 F-FDG PET/CT. Finally, the patient was eventually diagnosed with neuroendocrine carcinoma.

Intense 68 Ga-Pentixafor Activity in Idiopathic Retroperitoneal Fibrosis.

ABSTRACT: A 52-year-old man was admitted to our hospital with lower abdominal and low back pain, and abdomen CT at an outside hospital presented a retroperitoneal mass with left urinary tract obstruction and hydronephrosis. In 68 Ga-pentixafor PET/CT, the retroperitoneal mass showed intense radioactivity. Subsequently, the patient underwent biopsy of the retroperitoneal mass. The pathological examination showed only fibrous tissue without tumor cells. The patient was finally diagnosed with idiopathic retroperitoneal fibrosis. Our case demonstrated that idiopathic retroperitoneal fibrosis had intense uptake of 68 Ga-pentixafor.

Comparison of 18 F-MFBG and 68 Ga-DOTATATE PET/CT in the Imaging of Metastatic Paraganglioma and Pheochromocytoma.

ABSTRACT: Two men with metastatic paraganglioma/pheochromocytoma underwent PET/CT examination in our hospital to understand the treatment effect and progression of the disease. Both patients had previously been treated with 131 I-MIBG, and at this evaluation, both of them underwent 68 Ga-DOTATATE and 18 F-MFBG PET/CT. The 68 Ga-DOTATATE PET/CT showed more metastases in the images of these 2 patients. This case highlighted that 68 Ga-DOTATATE PET/CT is superior to 18 F-MFBG PET/CT in detecting metastases from paraganglioma and pheochromocytoma in these 2 patients.

Imaging Aldosterone-Producing Adrenocortical Carcinoma With 68 Ga-Pentixafor PET/CT.

ABSTRACT: Chemokine receptor 4 (CXCR4) is a 7-transmembrane G protein-coupled receptor, and pentixafor is considered to be a potent ligand for the CXCR4 receptor. Recently, 68 Ga-pentixafor has been reported as a potential PET imaging agent for CXCR4-positive tumors and inflammatory lesions, including adrenocortical lesions. We report a case of primary aldosteronism due to adrenocortical carcinoma with intense 68 Ga-pentixafor activity on PET/CT.