68Ga-DOTATATE PET in juvenile angiofibroma

Integrated Molecular and Histological Insights for Targeted Therapies in Mesenchymal Sinonasal Tract Tumors

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of mesenchymal sinonasal tract tumors (STTs), a distinct subset of STTs. Despite their rarity, mesenchymal STTs represent a unique clinical challenge, characterized by their rarity, often slow progression, and frequently subtle or overlooked symptoms. The complex anatomy of the sinonasal area, which includes critical structures such as the orbit, brain, and cranial nerves, further complicates surgical treatment options. This underscores an urgent need for more advanced and specialized therapeutic approaches.

RECENT FINDINGS

Advancements in molecular diagnostics, particularly in next-generation sequencing, have significantly enhanced our understanding of STTs. Consequently, the World Health Organization has updated its tumor classification to better reflect the distinct histological and molecular profiles of these tumors, as well as to categorize mesenchymal STTs with greater accuracy. The growing understanding of the molecular characteristics of mesenchymal STTs opens new possibilities for targeted therapeutic interventions, marking a significant shift in treatment paradigms. This review article concentrates on mesenchymal STTs, specifically addressing sinonasal tract angiofibroma, sinonasal glomangiopericytoma, biphenotypic sinonasal sarcoma, and skull base chordoma. These entities are marked by unique histopathological and molecular features, which challenge conventional treatment approaches and simultaneously open avenues for novel targeted therapies. Our discussion is geared towards delineating the molecular underpinnings of mesenchymal STTs, with the objective of enhancing therapeutic strategies and addressing the existing shortcomings in the management of these intricate tumors.

Clinical Applications of Somatostatin Receptor (Agonist) PET Tracers beyond Neuroendocrine Tumors

Somatostatin receptor (SSTR) agonist tracers used in nuclear medicine scans are classically used for neuroendocrine tumor diagnosis and staging. SSTR are however, expressed more widely in a variety of cells as seen in the distribution of physiological tracer uptake during whole body scans. This provides opportunities for using these tracers for applications other than NETs and meningiomas. In this qualitative systematic review, novel diagnostics in SSTR-PET imaging are reviewed. A total of 70 studies comprised of 543 patients were qualitatively reviewed. Sarcoidosis, atherosclerosis and phosphaturic mesenchymal tumors represent the most studied applications currently with promising results. Other applications remain in progress where there are many case reports but a relative dearth of cohort studies. [¹⁸F]FDG PET provides the main comparative method in many cases but represents a well-established general PET technique that may be difficult to replace, without prospective clinical studies.

Fusion 68Ga-DOTANOC PET/MRI in Primary Juvenile Nasal Angiofibroma

ABSTRACT

Somatostatin cell surface receptors are expressed in many different benign and malignant tumors and are often exploited for imaging and therapy of neuroendocrine tumors. A 17-year-old adolescent boy with clinicoradiologically diagnosed JNA (juvenile nasopharyngeal angiofibroma) also underwent 68Ga-DOTANOC PET to explore somatostatin cell surface receptors' expression and its theranostic potential. Fusion PET/MRI, a novel imaging technology, exactly depicted the anatomical extensions of the tumor with avid DOTANOC uptake. This software-based fusion technique is advantageous for easy early recurrence identification, better delineation from postoperative scar tissue, for planning the exact target volumes for stereotactic radiotherapy therapy of inoperable/residual/recurrent JNAs in the future.

Clinical utility of Ga68 DOTANOC PET/CT imaging in juvenile nasal angiofibroma and the PARIS protocol: a preliminary report

OBJECTIVES

Juvenile nasopharyngeal angiofibroma (JNA) expresses different somatostatin cell surface receptors and Ga68 [DOTA, 1-Nal3]-octreotide (DOTANOC)-PET/computed tomography (CT) scan may be used for its imaging. Also, functional imaging with DOTANOC-PET/CT may promise of greater accuracy in the detection or exclusion of recurrent/residual JNA.

METHODS

In this prospective study, five JNA patients who underwent a DOTANOC-PET-CT scan both preoperatively and postoperatively during June 2018-March 2020 were included. Postcontrast enhancement of a definite lesion was considered residual/recurrent tumor in contrast-enhanced MRI (CEMRI). In DOTANOC-PET/CT, any abnormal uptake apart from physiological sites was considered as residual lesions. Radiological results were categorized as negative, suspicious or definite residual/recurrent tumors. Any discrepancy was resolved by endoscopic biopsies.

RESULTS

Preoperatively all five cases of JNA showed avid DOTANOC expression in the tumor. The mean (SD) value of DOTANOC standardised uptake value in the tumor was 4.3 (1.4) (range = 2.1-6.2). In postoperative CEMRI evaluation, three of five patients had residual tumors and two had normal scans. On DOTANOC-PET/CT, two of five patients had residual tumors and three had normal scans. In one patient with residual tumor, the discrepancy with regard to tumor extent was noted in two scans, and further biopsy confirmed the findings of DOTANOC-PET/CT as accurate.

CONCLUSION

68Ga-DOTANOC-PET/CT uptake is universal in JNA and appears to be more specific in the identification of residual/recurrent JNA. In residual tumors, DOTANOC-PET/CT may have an advantage over CEMRI in the diagnosis, decision making and planning stereotactic radiation. However, these findings are to be validated in studies with larger patients.

68 Ga DOTANOC PET/CT Scan in Primary Juvenile Nasopharyngeal Angiofibroma - A Pilot Study

OBJECTIVES/HYPOTHESIS

Somatostatin receptors (SSTRs) are highly expressed in neuroendocrine tumors and is exploited for its imaging and treatment. SSTRs expression is also demonstrated in diverse benign and malignant tumor cell types and proliferating peri-tumoral vessels. Similarly, Juvenile Nasopharyngeal Angiofibroma (JNA) expresses different SSTRs and may be utilized for its imaging and treatment using DOTA, 1-Nal3-octreotide (DOTANOC)-PET/CT scan.

STUDY DESIGN

Prospective cohort.

METHODS

Nineteen clinico-radiologically diagnosed primary JNA patients underwent a ⁶⁸ Ga-DOTANOC PET-CT scan. Using a dedicated PET/CT scanner, a low-dose head and neck spot CT scan was performed after 45 to 60 minutes of intravenous injection of 2 to 3 mCi(74-111 MBq) of DOTANOC. The primary objective was to assess the intensity and pattern of DOTANOC uptake in these patients.

RESULTS

DOTANOC expression was noted in all cases (n = 19) of primary JNA (100%). The mean (SD) DOTANOC SUVmax ratio of tumor and background was 6.9+/-1.4(range, 3.8-9.5). Intra-cranial extension in all 13/19 patients was prominently visualized due to the absence of DOTANOC uptake in the brain. Compared to the background all stages of JNA showed significant DOTANOC uptake (P < .0001). No difference in uptake between advanced-stage tumors and early tumors was noted (P = .47). A statistically non-significant negative trend was noted for decreasing uptake with increasing age (Spearman correlation coefficient, r = -0.19).

CONCLUSIONS

This first study of ⁶⁸ Ga-DOTANOC-PET/CT scan in JNA demonstrates consistent and reliable uptake activity in all patients irrespective of age and stage. This opens up possibilities to physiological diagnostic imaging with a promise of greater specificity and sensitivity and may have applications in ambivalent diagnostic situations such as the detection of recurrence.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:1509-1515, 2021.

Clinical Utility of 68Ga-DOTANOC Positron Emission Tomography-Computed Tomography Scan on Postoperative Assessment of Juvenile Nasal Angiofibroma

Somatostatin cell surface receptors are expressed on the peritumoral vessels of various benign and malignant neoplasms including angiofibromas. Positive initial uptake on positron emission tomography-computed tomography (PET/CT) imaging with ⁶⁸Ga-labeled DOTANOC is noted in a patient with juvenile nasal angiofibroma (JNA), and the same is noted to be absent following complete surgical excision. Functional ⁶⁸Ga-DOTANOC PET/CT may be an early useful tool for JNA residual/recurrence identification and precise postoperative surveillance.

Juvenile Nasal Angiofibroma on 68Ga-DOTANOC PET/CT: Exploring Theranostic Avenues

Somatostatin (SST) cell surface receptors (SSTRs) are expressed in many different malignant, benign, and neuroendocrine tumors. SSTRs are also expressed in the endothelium of human vessels during angiogenesis and not in the nonproliferating vessels. We present a case of 19-year-old boy with juvenile nasal angiofibroma (JNA), who underwent ⁶⁸Ga-DOTANOC PET/CT to explore SSTRs expression and theranostic potential. The scan revealed high uptake in the tumor, and in certain areas, the uptake was similar to that of the pituitary gland. Performance of DOTANOC PET/CT in JNA opens up new frontiers with respect to radiological staging, early recurrence identification, better delineation from postoperative scar tissue, possible preoperative treatment with SST analogs, and perhaps even radiopharmaceutical based-ligand therapy of inoperable/residual/recurrent JNAs in the future.

The Genetic and Molecular Determinants of Juvenile Nasopharyngeal Angiofibroma: A Systematic Review

Objective:

Juvenile nasopharyngeal angiofibroma (JNA) is a rare vascular tumor of unknown etiology. Studies investigating the molecular and genetic determinants of JNA are limited by small sample size and inconsistent approaches. The purpose of this study is to examine all eligible JNA studies in aggregate, applying qualitative analysis to highlight areas of particular relevance, including potential targets for therapeutic intervention.

Methods:

The PubMed, MEDLINE, Embase, Web of Science, Cochrane, and CINAHL databases were screened with inclusion and exclusion criteria applied to all citations. Manuscripts investigating the genetic determinants, histopathogenesis, and heritability of juvenile nasopharyngeal angiofibroma were included. Non-English studies, case reports, and articles focusing on clinical management without original data were excluded. Full text articles were obtained. A qualitative synthesis of data was performed.

Results:

A total of 59 articles met criteria for inclusion. These were divided into 6 categories based on the primary topic or target discussed, (1) steroid hormone receptors, (2) chromosomal abnormalities, (3) growth factors, (4) genetic targets, (5) molecular targets, (6) Wnt cell signaling, and (7) studies that overlapped multiple of the aforementioned categories. Although relatively low n values prevent definitive conclusions to be drawn, a predominance of certain molecular targets such as vascular endothelial growth factor (VEGF) and Wnt/β-catenin pathway intermediaries is apparent.

Conclusions:

Although the etiology of JNA remains elusive, contemporary molecular genetic investigation holds promise for risk stratification and could form the basis of a modernized staging system. A multicenter clinical registry and linked tissue bank would further promote the search for JNA specific biomarkers.