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

FAPI-avid Lesions in the Brain: A Case Report on 99mTc-FAPI-46 Scintigraphy in Glioblastoma Multiforme

A 63-year-old man presented with transient global amnesia, urinary incontinence, and a visual field deficit. MRI revealed a heterogeneous mass in the left parieto-occipital lobe, diagnosed as glioblastoma multiforme (GBM). Following craniotomy, chemotherapy with temozolomide and radiotherapy were initiated. Two months after radiotherapy, MRI indicated possible tumor recurrence, leading to a change in treatment. Despite further interventions, the patient exhibited new-appearing symptoms and a significant increase in mass size. A 99mTc-FAPI-46 scintigraphy showed avidity in the tumoral recurrence. This case highlights the potential of this novel, low-cost imaging technique for assessing eligibility for potential radio-ligand therapy in resource-limited countries.

FAP-targeted PET/CT imaging in patients with breast cancer from a prospective bi-center study: insights into diagnosis and clinic management

PURPOSE

To evaluate the diagnostic accuracy and clinical impact of fibroblast activation protein (FAP)-targeted PET/CT imaging in primary and metastatic breast cancer and compare the results with those of standard-of-care imaging (SCI) and [18F]FDG PET/CT.

METHODS

We prospectively analyzed patients with diagnosed or suspected breast cancer who underwent concomitant FAP-targeted PET/CT (radiotracers including either [68Ga]Ga-FAPI-46 or [18F]FAPI-42) and [18F]FDG PET/CT scans from June 2020 to January 2024 at two medical centers. Breast ultrasound (US) imaging was performed in all treatment-naïve patients as SCI. The SUVmax, tumor-to-background ratio (TBR), lesion detection rate, and tumor-node-metastasis (TNM) classifications between FAP-targeted and [18F]FDG PET/CT were evaluated and compared.

RESULTS

Sixty-one female patients (median age, 52 y; range, 28-82 y) were included. Among them, 23 patients underwent evaluation for a definitive diagnosis of suspected breast lesions, 15 underwent initial staging, and 23 were evaluated for the detection of recurrence. The sensitivities of breast US, [18F]FDG, and FAP-targeted PET/CT for detecting primary breast tumors were 82%, 79%, and 100%, respectively. Regarding the diagnosis of recurrent/metastatic lesions, the lesion-based detection rate of FAP-targeted PET/CT was significantly higher than that of [18F]FDG, which included local and regional recurrence, neck lymph node (LN), abdomen LN, bone, and liver metastases. Compared with [18F]FDG PET/CT, FAP-targeted PET/CT altered thirteen patients' TNM staging/restaging (13/59, 22%) and nine patients' clinical management (9/59, 15%). Compared to SCI, FAPI changed fourteen patients' TNM staging/re-staging (14/59, 24%) and eleven patients' therapeutic regimens(11/59, 19%). There was no significant association between FAPI-derived SUVmax and receptor status/histologic type in both primary and metastatic lesions.

CONCLUSION

FAP-targeted PET/CT was superior to [18F]FDG in diagnosing primary and metastatic breast cancer, with higher radiotracer uptake and TBR, especially in the detection of primary/recurrent tumors, abdominal LN metastases, liver, and bone metastases. FAP-targeted PET/CT is superior to [18F]FDG and SCI in TNM staging and may improve tumor staging, recurrence detection, and implementation of necessary treatment modifications.

Turning Points in Cross-Disciplinary Perspective of Primary Hyperparathyroidism and Pancreas Involvements: Hypercalcemia-Induced Pancreatitis, MEN1 Gene-Related Tumors, and Insulin Resistance

We aimed to provide an in-depth analysis with respect to three turning points in pancreas involvement in primary hyperparathyroidism (PHP): hypercalcemia-induced pancreatitis (HCa-P), MEN1 (multiple endocrine neoplasia)-related neuroendocrine tumors (NETs), and insulin resistance (IR). This was a comprehensive review conducted via a PubMed search between January 2020 and January 2024. HCa-P (n = 9 studies, N = 1375) involved as a starting point parathyroid NETs (n = 7) or pancreatitis (n = 2, N = 167). Case report-focused analysis (N = 27) showed five cases of pregnancy PHP-HCa-P and three reports of parathyroid carcinoma (female/male ratio of 2/1, ages of 34 in women, men of 56). MEN1-NET studies (n = 7) included MEN1-related insulinomas (n = 2) or MEN1-associated PHP (n = 2) or analyses of genetic profile (n = 3), for a total of 877 MEN1 subjects. In MEN1 insulinomas (N = 77), the rate of associated PHP was 78%. Recurrence after parathyroidectomy (N = 585 with PHP) was higher after less-than-subtotal versus subtotal parathyroidectomy (68% versus 45%, p < 0.001); re-do surgery was 26% depending on surgery for pancreatic NETs (found in 82% of PHP patients). MEN1 pathogenic variants in exon 10 represented an independent risk factor for PHP recurrence. A single pediatric study in MEN1 (N = 80) revealed the following: a PHP rate of 80% and pancreatic NET rate of 35% and 35 underlying germline MEN1 pathogenic variants (and 3/35 of them were newly detected). The co-occurrence of genetic anomalies included the following: CDC73 gene variant, glucokinase regulatory protein gene pathogenic variant (c.151C>T, p.Arg51*), and CAH-X syndrome. IR/metabolic feature-focused analysis identified (n = 10, N = 1010) a heterogeneous spectrum: approximately one-third of adults might have had prediabetes, almost half displayed some level of IR as reflected by HOMA-IR > 2.6, and serum calcium was positively correlated with HOMA-IR. Vitamin D deficiency was associated with a higher rate of metabolic syndrome (n = 1). Normocalcemic and mildly symptomatic hyperparathyroidism (n = 6, N = 193) was associated with a higher fasting glucose and some improvement after parathyroidectomy. This multilayer pancreas/parathyroid analysis highlighted a complex panel of connections from pathogenic factors, including biochemical, molecular, genetic, and metabolic factors, to a clinical multidisciplinary panel.

Increased 68 Ga-FAPI Uptake in Capillary Hemangiomas in an Adult Patient

ABSTRACT

A 67-year-old woman was enrolled in our 68 Ga-FAPI PET/CT tumor clinical trial due to her lung adenocarcinoma. The PET/CT scan additionally revealed increased uptake of FAPI in the tongue. Combined with the patient's medical history and the contrast-enhanced CT of the maxillofacial region, it was suspected to be a hemangioma. Subsequently, the patient underwent surgery and was diagnosed with capillary hemangioma of the left side of her tongue.

A retrospective study of 68Ga-FAPI PET/CT in differentiating the nature of pulmonary lesions

Purpose

This study aimed to investigate the characteristics of various pulmonary lesions as revealed by 68Ga-FAPI PET/CT and to determine the utility of 68Ga-FAPI PET/CT in distinguishing the nature of these pulmonary lesions.

Methods

A retrospective analysis was conducted on 99 patients with pulmonary lesions, who were categorized into three distinct groups: primary lung tumors (G1), metastatic lung tumors (G2), and benign lesions (G3). Each participant underwent a 68Ga-FAPI PET/CT scan. Among these groups, variables such as the Tumor/Background Ratio (TBR), Maximum Standardized Uptake Value (SUVmax), and the true positive rate of the lesions were compared. Furthermore, the FAPI uptake in nodular-like pulmonary lesions (d<3cm) and those with irregular borders was evaluated across the groups. A correlation analysis sought to understand the relationship between FAPI uptake in primary and pulmonary metastatic lesions.

Results

The study's participants were composed of 52 males and 47 females, with an average age of 56.8 ± 13.2 years. A higher uptake and detection rate for pulmonary lesions were exhibited by Group G1 compared to the other groups (SUVmax [G1 vs. G2 vs. G3: 9.1 ± 4.1 vs. 6.1 ± 4.1 vs. 5.3 ± 5.8], P<0.05; TBR [G1 vs. G2 vs. G3: 6.2 ± 2.4 vs. 4.1 ± 2.2 vs. 3.2 ± 2.7], P<0.01; true positive rate 95.1% vs. 88% vs. 75.6%]. In nodular-like lung lesions smaller than 3 cm, G1 showed a significantly higher FAPI uptake compared to G2 and G3 (SUVmax [G1 vs. G2 vs. G3: 8.8 ± 4.3 vs. 5.2 ± 3.2 vs. 4.9 ± 6.1], P<0.01; TBR [G1 vs. G2 vs. G3: 5.7 ± 2.7 vs. 3.7 ± 2.1 vs. 3.3 ± 4.4], P<0.05). Both G1 and G2 demonstrated significantly elevated FAPI agent activity in irregular-bordered pulmonary lesions when compared to G3 (SUVmax [G1 vs. G2 vs. G3: 10.9 ± 3.3 vs. 8.5 ± 2.7 vs. 4.6 ± 2.7], P<0.01; TBR [G1 vs. G2 vs. G3: 7.2 ± 2.1 vs. 6.4 ± 1.3 vs. 3.2 ± 2.4], P<0.01). A positive correlation was identified between the level of 68Ga-FAPI uptake in primary lesions and the uptake in pulmonary metastatic lesions within G2 (r=0.856, P<0.05).

Conclusion

68Ga-FAPI PET/CT imaging proves to be of significant value in the evaluation of pulmonary lesions, offering distinctive insights into their nature.

Comparison of the 68 Ga-FAPI Versus 18 F-FDG in Gastric Adenocarcinoma and Anthracosis-Associated Lymph Nodes: FAPI Unmasking False-Negatives and False-Positives

ABSTRACT

A 73-year-old woman with poorly differentiated gastric adenocarcinoma was referred to 18 F-FDG PET/CT for evaluation of the disease. FDG PET/CT showed intense uptake in the disseminated lymph nodes. However, there was no uptake in the primary tumoral lesion. Subsequently, 68 Ga-FAPI-04 PET/CT was performed with the decision of the tumor board and demonstrated intense uptake in the tumoral lesion. However, there was low or no uptake in disseminated lymph nodes. Tru-cut biopsy results revealed that all the lymph nodes were associated with anthracosis.

Advancements in theranostic applications: exploring the role of fibroblast activation protein inhibition tracers in enhancing thyroid health assessment

BACKGROUND

The diagnostic accuracy of [18F]-fluorodeoxyglucose ([18F]-FDG) positron emission tomography imaging in accurately identifying thyroid lesions is limited, primarily due to the physiological uptake of normal head and neck tissues and inflammatory uptake in lymph nodes. Since fibroblast activating protein is highly expressed in tumors and largely unexpressed in normal tissues, quinoline-based fibroblast activating protein inhibitors (FAPI) have emerged as promising tools in the diagnosis of cancer and other medical conditions. Several studies have reported on the feasibility and value of FAPI in thyroid cancer.

MAIN BODY

In this narrative review, we summarize the current literature on state-of-the-art FAPI positron emission tomography imaging for thyroid cancer and fibroblast activating protein-targeted radionuclide therapy. We provide an overview of FAPI uptake in normal thyroid tissue, thyroid cancer and its metastases. Additionally, we highlight the difference between FAPI uptake and [18F]-FDG uptake in thyroid lesions. Furthermore, we discuss the therapeutic value of FAPI in iodine-refractory thyroid cancer.

CONCLUSION

The utilization of fibroblast activating protein inhibitors in thyroid cancer holds significant promise, offering clinicians valuable insights for more precise diagnose choices and treatments strategies in the future.