Performance of 68Ga-DOTA–Conjugated Somatostatin Receptor–Targeting Peptide PET in Detection of Pheochromocytoma and Paraganglioma: A Systematic Review and Metaanalysis

Head and Neck Paraganglioma (HNPGL) Registry: A study protocol for prospective data collection in patients with Head and Neck Paragangliomas

INTRODUCTION

There is a lack of comprehensive and uniform data on head and neck paragangliomas (HNPGLs), and research is challenging due to its rarity and the involvement of multiple medical specialties. To improve current research data collection, we initiated the Head and Neck Paraganglioma Registry (HNPGL Registry). The aim of the HNPGL Registry is to a) collect extensive data on all HNPGL patients through a predefined protocol, b) give insight in the long term outcomes using patient reported outcome measures (PROMs), c) create uniformity in the diagnostic and clinical management of these conditions, and thereby d) help provide content for future (randomized) research.

METHODS AND ANALYSIS

The HNPGL Registry is designed as a prospective longitudinal observational registry for data collection on HNPGL patients and carriers of (likely) pathogenic variants causative of HNPGLs. All patients, regardless of the received treatment modality, can be included in the registry after informed consent is obtained. All relevant data regarding the initial presentation, diagnostics, treatment, and follow-up will be collected prospectively in an electronic case report form. In addition a survey containing the EuroQol 5D-5L (EQ-5D-5L), European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), Modified Fatigue Impact Scale (MFIS), Short QUestionnaire to Assess Health-enhancing physical activity (SQUASH), Cancer Worry Scale (CWS) and Hospital Anxiety and Depression Scale (HADS) will be sent periodically. The registry protocol was approved by the Medical Ethical Review Board of the University Medical Center Utrecht.

CONCLUSION

The HNPGL Registry data will be used to further establish the optimal management for HNPGL patients and lay the foundation for guideline recommendations and the outline of future research.

Presentation of metastatic carotid body paraganglioma on F-18 FDG PET/CT: a rare disease

Carotid body paraganglioma is a slow growing tumor of head and neck region. It can rarely be malignant in nature which is characterized by distant metastases on anatomical imaging. We share an interesting presentation of a malignant carotid body on F-18 FDG PET/CT in form of liver and skeletal metastases.

[68Ga]DOTATOC PET-derived radiomics to predict genetic background of head and neck paragangliomas: a pilot investigation

PURPOSE

To investigate the [68Ga]DOTATOC PET radiomic profile of head and neck paragangliomas (HNPGLs) and identify radiomic characteristics useful as predictors of succinate dehydrogenase genes (SDHx) pathogenic variants.

METHODS

Sporadic and SDHx HNPGL patients, who underwent [68Ga]DOTATOC PET/CT, were retrospectively included. HNPGLs were analyzed using LIFEx software, and extracted features were harmonized to correct for batch effects and confronted testing for multiple comparison. Stepwise discriminant analysis was conducted to remove redundancy and identify best discriminating features. ROC analysis was used to define optimal cut-offs. Multivariate decision-tree analysis was performed using CHAID method.

RESULTS

34 patients harboring 60 HNPGLs (51 SDHx in 25 patients) were included. Three sporadic and nine SDHx HNPGLs were metastatic. At stepwise discriminant analysis, both GLSZM-Zone Size Non-Uniformity (ZSNU, reflecting tumor heterogeneity) and IB-TLSRE (total lesion somatostatin receptor expression) were independent predictors of genetic status, with 96.4% of lesions and 91.6% of patients correctly classified after cross validation (p < 0.001). Among non-metastatic patients, GLSZM-ZSNU and IB-TLSRE were significantly higher in sporadic than SDHx HNPGLs (p < 0.001). No differences were revealed in metastatic patients. Decision-tree analysis highlights multifocality and IB-TLSRE as useful variables, correctly identifying 6/9 sporadic and 24/25 SDHx patients. Model failed to classify one SDHA and three sporadic patients (2 metastatic).

CONCLUSION

Radiomics features GLSZM-ZSNU and IB-TLSRE appear to reflect HNPGLs SDHx status and tumor behavior (metastatic vs. non-metastatic). If validated, especially IB-TLSRE might represent a simple and time-efficient radiomic index for SDHx variants early screening and prediction of tumor behavior in HNPGL cases.

Somatostatin receptor subtype 2A expression and genetics in 184 paragangliomas: a single center retrospective observational study

PURPOSE

Adrenal and extra-adrenal paragangliomas (PGLs) are a group of neuroendocrine tumors (NETs) with strong heterogeneity, which often express somatostatin receptor subtype 2 A (SSTR2A). However, the association between SSTR2A expression and genetic status of PGLs remains unclear. The purpose of the study was to identify whether various pathogenic variants (PVs) had an impact on SSTR2A expression in PGLs.

METHODS

This retrospective study included 184 patients with pathologically confirmed PGLs. The immunohistochemical expression of SSTR2A were studied in 184 tumors and PVs were tested in 159 tumor samples. Clinical and genetic data were compared in SSTR2A positive and negative PGLs.

RESULTS

SSTR2A was positive in 63.6% (117/184) of all tumors. PGLs with negative SSTR2A were more likely to be extra-adrenal (37.0% vs 18.0%; P = 0.005) and exhibited a considerably greater proportion of PVs (75.4% vs. 49.0%; P = 0.001) than those with positive SSTR2A. Compared to those without PVs, a higher proportion of PGLs with PVs in cluster 1B (P = 0.004) and cluster 2 (P = 0.004) genes, especially VHL (P = 0.009), FGFR1 (P = 0.010) and HRAS (P = 0.007), were SSTR2A negative. SSTR2A was positive in all tumors (4/4) with SDHx PVs and in 87.5% (7/8) of metastatic PGLs.

CONCLUSIONS

SSTR2A negativity was correlated with extra-adrenal tumor location and PVs in cluster 1B and cluster 2 genes such as VHL, FGFR1 and HRAS. Immunohistochemistry of SSTR2A should be taken into consideration in the personalized management of PGLs.

Radio theranostics in paragangliomas and pheochromocytomas

This continuing education aims to present in a clear and easy-to-understand manner the biology of paragangliomas and pheochromocytomas (PPGLs), the functional imaging studies available for their diagnosis and therapeutic planning, the requirements necessary to administer radioligand therapy (RLT) and the characteristics of these treatments (inclusion criteria, administration protocols, adverse effects and future perspectives). In this pathology we have two RLT options: [131I]MIBG and [177Lu]Lu-DOTA-TATE. The indication for treatment is determined by the expression of its therapeutic target in functional imaging studies, allowing precision and personalized medicine. Although most of the results we have for both treatments have as origin small retrospective series, RLT is presented as a safe and well-tolerated therapeutic option in PPGLs with slow-moderate progression or with uncontrollable symptoms, obtaining high disease control rates.

Gastroenteropancreatic neuroendocrine neoplasms: current development, challenges, and clinical perspectives

Neuroendocrine neoplasms (NENs) are highly heterogeneous and potentially malignant tumors arising from secretory cells of the neuroendocrine system. Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are the most common subtype of NENs. Historically, GEP-NENs have been regarded as infrequent and slow-growing malignancies; however, recent data have demonstrated that the worldwide prevalence and incidence of GEP-NENs have increased exponentially over the last three decades. In addition, an increasing number of studies have proven that GEP-NENs result in a limited life expectancy. These findings suggested that the natural biology of GEP-NENs is more aggressive than commonly assumed. Therefore, there is an urgent need for advanced researches focusing on the diagnosis and management of patients with GEP-NENs. In this review, we have summarized the limitations and recent advancements in our comprehension of the epidemiology, clinical presentations, pathology, molecular biology, diagnosis, and treatment of GEP-NETs to identify factors contributing to delays in diagnosis and timely treatment of these patients.

A comparative analysis of surgically excised hereditary and sporadic pheochromocytomas: Insights from a single-center experience

Pheochromocytoma is a tumor that usually originating from adrenal medullary chromaffin cells and producing one or more catecholamines, can manifest as hereditary or sporadic. While the majority pheochromocytomas are sporadic, hereditary forms are often associated with genetic syndromes such as von Hippel-Lindau, multiple endocrine neoplasia type 2, and neurofibromatosis type 1. This study aims to analyze data from our series of surgically excited pheochromocytoma patients and compare the characteristics between hereditary and sporadic cases. We retrospectively evaluated 33 diagnosed pheochromocytoma patients, documenting clinical features, surgical complications, and tumor characteristics in both hereditary and sporadic cases. Among the patients, 21% (7 individuals) had hereditary pheochromocytoma, while 79% (26 individuals) had sporadic cases. During diagnosis, hereditary pheochromocytoma patients exhibited a significantly lower mean age compared to the sporadic group (26.4 ± 9.9 years vs. 50.4 ± 14.0 years; p < 0.001). The maximum tumor size was also lower in hereditary cases compared to sporadic cases (p = 0.004). Adrenal tumor localization analysis showed that 63.6% were right-sided, 24.2% were left-sided, and 12.1% were bilateral. Laboratory analysis revealed significantly higher urinary norepinephrine levels in hereditary pheochromocytoma patients (p = 0.021). Our findings suggest that hereditary pheochromocytoma cases are characterized by a younger age at diagnosis, smaller tumor size, and a higher prevalence of multiple bilateral adrenal adenomas. We recommend genetic testing for all pheochromocytoma patients, particularly those with early-onset disease and bilateral adrenal tumors.

Role of 18F-FDG PET/CT in Head and Neck Squamous Cell Carcinoma: Current Evidence and Innovative Applications

This article provides an overview of the use of 18F-FDG PET/CT in various clinical scenarios of head-neck squamous cell carcinoma, ranging from initial staging to treatment-response assessment, and post-therapy follow-up, with a focus on the current evidence, debated issues, and innovative applications. Methodological aspects and the most frequent pitfalls in head-neck imaging interpretation are described. In the initial work-up, 18F-FDG PET/CT is recommended in patients with metastatic cervical lymphadenectomy and occult primary tumor; moreover, it is a well-established imaging tool for detecting cervical nodal involvement, distant metastases, and synchronous primary tumors. Various 18F-FDG pre-treatment parameters show prognostic value in terms of disease progression and overall survival. In this scenario, an emerging role is played by radiomics and machine learning. For radiation-treatment planning, 18F-FDG PET/CT provides an accurate delineation of target volumes and treatment adaptation. Due to its high negative predictive value, 18F-FDG PET/CT, performed at least 12 weeks after the completion of chemoradiotherapy, can prevent unnecessary neck dissections. In addition to radiomics and machine learning, emerging applications include PET/MRI, which combines the high soft-tissue contrast of MRI with the metabolic information of PET, and the use of PET radiopharmaceuticals other than 18F-FDG, which can answer specific clinical needs.

Imaging of Pheochromocytomas and Paragangliomas

Pheochromocytomas/paragangliomas are unique in their highly variable molecular landscape driven by genetic alterations, either germline or somatic. These mutations translate into different clusters with distinct tumor locations, biochemical/metabolomic features, tumor cell characteristics (eg, receptors, transporters), and disease course. Such tumor heterogeneity calls for different imaging strategies in order to provide proper diagnosis and follow-up. This also warrants selection of the most appropriate and locally available imaging modalities tailored to an individual patient based on consideration of many relevant factors including age, (anticipated) tumor location(s), size, and multifocality, underlying genotype, biochemical phenotype, chance of metastases, as well as the patient's personal preference and treatment goals. Anatomical imaging using computed tomography and magnetic resonance imaging and functional imaging using positron emission tomography and single photon emission computed tomography are currently a cornerstone in the evaluation of patients with pheochromocytomas/paragangliomas. In modern nuclear medicine practice, a multitude of radionuclides with relevance to diagnostic work-up and treatment planning (theranostics) is available, including radiolabeled metaiodobenzylguanidine, fluorodeoxyglucose, fluorodihydroxyphenylalanine, and somatostatin analogues. This review amalgamates up-to-date imaging guidelines, expert opinions, and recent discoveries. Based on the rich toolbox for anatomical and functional imaging that is currently available, we aim to define a customized approach in patients with (suspected) pheochromocytomas/paragangliomas from a practical clinical perspective. We provide imaging algorithms for different starting points for initial diagnostic work-up and course of the disease, including adrenal incidentaloma, established biochemical diagnosis, postsurgical follow-up, tumor screening in pathogenic variant carriers, staging and restaging of metastatic disease, theranostics, and response monitoring.

Theranostics in Neuroendocrine Tumors

ABSTRACT

Neuroendocrine tumors (NETs) are rare tumors that develop from cells of the neuroendocrine system and can originate in multiple organs and tissues such as the bowels, pancreas, adrenal glands, ganglia, thyroid, and lungs. This review will focus on gastroenteropancreatic NETs (more commonly called NETs) characterized by frequent somatostatin receptor (SSTR) overexpression and pheochromocytomas/paragangliomas (PPGLs), which typically overexpress norepinephrine transporter. Advancements in SSTR-targeted imaging and treatment have revolutionized the management of patients with NETs. This comprehensive review delves into the current practice, discussing the use of the various Food and Drug Administration-approved SSTR-agonist positron emission tomography tracers and the predictive imaging biomarkers, and elaborating on 177Lu-DOTATATE peptide receptor radionuclide therapy including the evolving areas of posttherapy imaging practices and peptide receptor radionuclide therapy retreatment. SSTR-targeted imaging and therapy can also be used in patients with PPGL; however, this patient population has demonstrated the best outcomes from norepinephrine transporter-targeted therapy with 131I-metaiodobenzylguanidine. Metaiodobenzylguanidine theranostics for PPGL will be discussed, noting that in 2024 it became commercially unavailable in the United States. Therefore, the use and reported success of SSTR theranostics for PPGL will also be explored.

Paraganglioma of the Neck: A Rare Case With Spinal Metastasis

Paragangliomas are rare neuroendocrine tumors that arise from the paraganglia, which are clusters of neuroendocrine cells associated with the autonomic nervous system. These tumors are commonly found in the adrenal medulla but can also occur in other locations outside the adrenal gland. Here, we present a case report of a slow-growing paraganglioma in the left neck with spinal metastasis in a 60-year-old man. This case highlights the importance of considering paraganglion tumors in the differential diagnosis of neck masses and the need for early diagnosis and management to prevent potential complications. Importantly, both the clinical picture and anatomical location of these tumors is important when determining treatment plans.

Recent Progress in Peptide-Based Molecular Probes for Disease Bioimaging

Recent strides in molecular pathology have unveiled distinctive alterations at the molecular level throughout the onset and progression of diseases. Enhancing the in vivo visualization of these biomarkers is crucial for advancing disease classification, staging, and treatment strategies. Peptide-based molecular probes (PMPs) have emerged as versatile tools due to their exceptional ability to discern these molecular changes with unparalleled specificity and precision. In this Perspective, we first summarize the methodologies for crafting innovative functional peptides, emphasizing recent advancements in both peptide library technologies and computer-assisted peptide design approaches. Furthermore, we offer an overview of the latest advances in PMPs within the realm of biological imaging, showcasing their varied applications in diagnostic and therapeutic modalities. We also briefly address current challenges and potential future directions in this dynamic field.

3-[18F]Fluoro-para-hydroxyphenethylguanidine (3-[18F]pHPG) PET-A Novel Imaging Modality for Paraganglioma

Context

Functional positron emission tomography (PET) imaging for the characterization of pheochromocytoma and paraganglioma (PCC/PGL) and for detection of metastases in malignant disease, offers valuable clinical insights that can significantly guide patient treatment.

Objective

This work aimed to evaluate a novel PET radiotracer, 3-[18F]fluoro-para-hydroxyphenethylguanidine (3-[18F]pHPG), a norepinephrine analogue, for its ability to localize PCC/PGL.

Methods

3-[18F]pHPG PET/CT whole-body scans were performed on 16 patients (8 male:8 female; mean age 47.6 ± 17.6 years; range, 19-74 years) with pathologically confirmed or clinically diagnosed PCC/PGL. After intravenous administration of 304 to 475 MBq (8.2-12.8 mCi) of 3-[18F]pHPG, whole-body PET scans were performed at 90 minutes in all patients. 3-[18F]pHPG PET was interpreted for abnormal findings consistent with primary tumor or metastasis, and biodistribution in normal organs recorded. Standardized uptake value (SUV) measurements were obtained for target lesions and physiological organ distributions.

Results

3-[18F]pHPG PET showed high radiotracer uptake and trapping in primary tumors, and metastatic tumor lesions that included bone, lymph nodes, and other solid organ sites. Physiological biodistribution was universally present in salivary glands (parotid, submandibular, sublingual), thyroid, heart, liver, adrenals, kidneys, and bladder. Comparison [68Ga]DOTATATE PET/CT was available in 10 patients and in all cases showed concordant distribution. Comparison [123I]meta-iodobenzylguanidine [123I]mIBG planar scintigraphy and SPECT/CT scans were available for 4 patients, with 3-[18F]pHPG showing a greater number of metastatic lesions.

Conclusion

We found the kinetic profile of 3-[18F]pHPG PET affords high activity retention within benign and metastatic PCC/PGL. Therefore, 3-[18F]pHPG PET imaging provides a novel modality for functional imaging and staging of malignant paraganglioma with advantages of high lesion affinity, whole-body coregistered computed tomography, and rapid same-day imaging.

Quarter Century PET/Computed Tomography Transformation of Oncology: Neuroendocrine Tumors

Significant improvement in molecular imaging and theranostics in the management of neuroendocrine tumors (NETs) has been made in the last few decades. Somatostatin receptor-targeted PET imaging outperforms conventional, planar, and single-photon emission computed tomography imaging and is indicated in the evaluation of these patients when available, resulting in a significant impact on staging, treatment response assessment, and restaging of these patients. Radionuclide therapy can have an impact on patient outcome in metastatic disease when not many treatment options are available.

The Additional Value of Somatostatin Receptor Positron Emission Computed Tomography ([68Ga]Ga-DOTATOC PET/CT) Compared with Magnetic Resonance Imaging of the Head and Neck Region in Paraganglioma Patients: A Pilot Study

The Dutch guideline for patients suspected of head and neck paragangliomas (HNPGLs) recommends magnetic resonance imaging (MRI) and/or computed tomography (CT) of the head and neck area. Additionally, it suggests considering additional nuclear imaging. The aim of this study was to evaluate the outcomes of [68Ga]Ga-DOTATOC PET/CT compared to MRI in patients with suspected HNPGLs and carriers of genetic variations.

METHODS

In this single-center pilot study, retrospective data were obtained from consecutive patients between 2016 and 2023. Both MRI and [68Ga]Ga-DOTATOC PET/CT were performed within 12 months. The primary outcome was the location of HNPGLs.

RESULTS

A total of 25 consecutive patients were included, and 7 patients (28.0%, p = 0.5) showed differences between the imaging modalities, of whom 5 patients had unexpected localizations with additional uptake by somatostatin receptors (SSTR) on the [68Ga]Ga-DOTATOC PET/CT.

CONCLUSIONS

The authors recommend performing baseline imaging with [68Ga]Ga-DOTATOC PET/CT (if available) in variant carriers and using MRI/CT for follow-up according to the regional protocol, thereby shifting the gold standard for baseline imaging from MRI/CT to [68Ga]Ga-DOTATOC PET/CT.

A Prospective Comparative Study of 18 F-FDOPA PET/CT Versus 123 I-MIBG Scintigraphy With SPECT/CT for the Diagnosis of Pheochromocytoma and Paraganglioma

PURPOSE

This study aimed to compare the diagnostic performances of 18 F-FDOPA PET/CT and 123 I-MIBG scintigraphy with SPECT/CT for detection of pheochromocytoma and paraganglioma (PPGL).

PATIENTS AND METHODS

We conducted a prospective, single-institution comparative study. Patients suspected of having PPGL or those showing recurrence and/or distant metastasis of PPGL were enrolled. The primary objective was to affirm the noninferiority of 18 F-FDOPA PET/CT for diagnostic sensitivity. Both 123 I-MIBG scintigraphy with SPECT/CT (at 4 and 24 hours) and 18 F-FDOPA PET/CT (at 5 and 60 minutes after radiotracer administration) were performed. The final diagnosis was established either pathologically or via clinical follow-up. Nuclear physicians, unaware of the clinical data, undertook image analysis.

RESULTS

Thirty-two patients were evaluated: 14 of 21 with an initial diagnosis and 9 of 11 with recurrence/metastasis had PPGLs in their final diagnoses. In patient-based analyses, 18 F-FDOPA PET/CT (95.7%) exhibited noninferior sensitivity compared with 123 I-MIBG SPECT/CT (91.3%), within the predetermined noninferiority margin of -12% by a 95% confidence interval lower limit of -10%. Both modalities showed no significant difference in specificity (88.9% vs 88.9%). In the region-based analysis for the recurrence/metastasis group, 18 F-FDOPA PET/CT demonstrated significantly higher sensitivity compared with 123 I-MIBG SPECT/CT (86.2% vs 65.5%, P = 0.031) and superior interobserver agreement (κ = 0.94 vs 0.85). The inclusion of an early phase in dual-phase 18 F-FDOPA PET/CT slightly improved diagnostic performance, albeit not to a statistically significant degree.

CONCLUSIONS

18 F-FDOPA PET/CT demonstrated noninferior sensitivity and comparable specificity to 123 I-MIBG SPECT/CT in the diagnosing PPGL. Notably, in the assessment of PPGL recurrence and metastasis, 18 F-FDOPA PET/CT outperformed 123 I-MIBG SPECT/CT in terms of both sensitivity and interobserver agreement.

Diagnosis and Management of Pheochromocytomas and Paragangliomas: A Guide for the Clinician

OBJECTIVE

The aim of this review was to provide a practical approach for clinicians regarding the diagnosis and management of pheochromocytomas and paragangliomas (PPGLs).

METHODS

A literature search of PubMed was carried out using key words, including pheochromocytoma, paraganglioma, treatment, diagnosis, screening, and management. The discussion of diagnosis and management of PPGL is based on the evidence available from prospective studies when available and mostly from cohort studies, cross-sectional studies, and expert consensus.

RESULTS

PPGL are neuroendocrine tumors arising from the chromaffin cells of adrenal medulla and sympathetic and parasympathetic ganglia, respectively. PPGL can be localized or metastatic, and they may secrete catecholamines, causing a variety of symptoms and potentially catastrophic and lethal complications if left untreated. The rarity of these tumors along with heterogeneous clinical presentation often poses challenges for the diagnosis and management. PPGL can be associated with several familial syndromes which are important to recognize.

CONCLUSION

The last few years have witnessed an exponential growth in the knowledge around PPGL. This review aims at providing a comprehensive discussion of current concepts for clinicians regarding clinical presentation, diagnostic tools, and management strategies for PPGL.

Abdominal Positron Emission Tomography/Magnetic Resonance Imaging

Hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) is highly suited for abdominal pathologies. A precise co-registration of anatomic and metabolic data is possible thanks to the simultaneous acquisition, leading to accurate imaging. The literature shows that PET/MRI is at least as good as PET/CT and even superior for some indications, such as primary hepatic tumors, distant metastasis evaluation, and inflammatory bowel disease. PET/MRI allows whole-body staging in a single session, improving health care efficiency and patient comfort.

Somatostatin Receptor-Directed PET/CT Can Differentiate Between Different Subtypes of Head and Neck Paragangliomas

BACKGROUND

Given their neuroendocrine origin, head and neck paragangliomas (HNPGLs) can be imaged with somatostatin receptor (SSTR)-directed PET/CT. We aimed to determine whether the in vivo PET signal can differentiate between varying HNPGL subtypes.

PATIENTS AND METHODS

Fourteen patients with HNPGL received pretherapeutic SSTR-PET/CTs using 68 Ga-DOTATOC. Six (42.9%) patients had a jugular paraganglioma (PGL-J), 5 (35.7%) were diagnosed with carotid paraganglioma (PGL-Cs), and the remaining 3 patients (21.4%) had PGL-C with pathogenic SDHx germline variants (PGL-C-SDH). A visual and quantitative assessment of the primary tumor on SSTR-PET was performed, including SUV max and target-to-background ratio (TBR). Quantitative values were then compared between subgroups of patients affected with different HNPGL entities.

RESULTS

On visual assessment, all primary HNPGLs could be identified on SSTR-PET/CT. Quantification of HNPGL revealed substantially elevated SUV max in PGL-J (101.7 ± 58.5) when compared with PGL-C-SDH (13.4 ± 5.6, P < 0.05), but not when compared with PGL-C (66.7 ± 27.3, P = 0.4; PGL-C vs PGL-C-SDH, P = 0.2). TBR of PGL-J (202.9 ± 82.2), however, further differentiated between PGL-C (95.7 ± 45.4, P < 0.05) and PGL-C-SDH (20.4 ± 12.2, P < 0.01; PGL-C vs PGL-C-SDH, P = 0.3). Moreover, whole-body readout revealed metastases in 2/3 (66.7%) of PGL-C-SDH patients, with a single SSTR-expressing skeletal lesion in one subject and bipulmonary lesions in the other patient.

CONCLUSIONS

In patients with HNPGL, SSTR-PET/CT identified the primary and metastatic disease and provides substantially elevated TBR, indicating excellent image contrast. PET-based quantification can also differentiate between varying HNPGL subtypes.

Caution on the Use of 68Ga-DOTATATE for the Diagnosis of Pheochromocytoma: A Report of 2 Cases

Pheochromocytomas are intra-adrenal sympathetic neuroendocrine tumors that arise from chromaffin cells. Paragangliomas similarly arise from chromaffin cells, although at extra-adrenal sites such as sympathetic paraganglia in the abdomen/thorax, or parasympathetic paraganglia in the head/neck. Collectively, pheochromocytomas and paragangliomas are important to diagnose and resect because they may secrete harmful levels of catecholamines, have mass effects, hemorrhage, and/or metastasize. Anatomic imaging of pheochromocytomas is usually completed with computed tomography or magnetic resonance imaging; however, functional imaging may be used to provide additional localization, staging, and/or biologic information. Accordingly, selection of the proper functional imaging modality can be critical to developing the optimal therapeutic strategy. 68Gallium- and 64Copper-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate positron emission tomography computed tomography (68Ga- and 64Cu-DOTATATE) are widely used in evaluating pheochromocytomas and paragangliomas, although data regarding the sensitivity for diagnosing pheochromocytoma are limited. We report 2 cases of pheochromocytoma that showed nondiagnostic 68Ga-DOTATATE uptake but were subsequently visualized using alternative functional imaging modalities. Additionally, we provide a review of the literature to highlight the underappreciated limitations of functional adrenal imaging with somatostatin-based compounds.

Dissecting a diagnostic enigma: Hypertension in a young patient from an organ of Zuckerkandl paraganglioma

Hypertension in young patients can mask rare conditions like paragangliomas, especially in the absence of conventional symptoms. A comprehensive diagnostic evaluation and multidisciplinary approach are crucial for optimal management and outcomes.

Metastatic Pheochromocytoma and Paraganglioma: Somatostatin Receptor 2 Expression, Genetics, and Therapeutic Responses

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) with pathogenic mutations in the succinate dehydrogenase subunit B (SDHB) are associated with a high metastatic risk. Somatostatin receptor 2 (SSTR2)-dependent imaging is the most sensitive imaging modality for SDHB-related PPGLs, suggesting that SSTR2 expression is a significant cell surface therapeutic biomarker of such tumors.

OBJECTIVE

Exploration of the relationship between SSTR2 immunoreactivity and SDHB immunoreactivity, mutational status, and clinical behavior of PPGLs. Evaluation of SSTR-based therapies in metastatic PPGLs.

METHODS

Retrospective analysis of a multicenter cohort of PPGLs at 6 specialized Endocrine Tumor Centers in Germany, The Netherlands, and Switzerland. Patients with PPGLs participating in the ENSAT registry were included. Clinical data were extracted from medical records, and immunohistochemistry (IHC) for SDHB and SSTR2 was performed in patients with available tumor tissue. Immunoreactivity of SSTR2 was investigated using Volante scores. The main outcome measure was the association of SSTR2 IHC positivity with genetic and clinical-pathological features of PPGLs.

RESULTS

Of 202 patients with PPGLs, 50% were SSTR2 positive. SSTR2 positivity was significantly associated with SDHB- and SDHx-related PPGLs, with the strongest SSTR2 staining intensity in SDHB-related PPGLs (P = .01). Moreover, SSTR2 expression was significantly associated with metastatic disease independent of SDHB/SDHx mutation status (P < .001). In metastatic PPGLs, the disease control rate with first-line SSTR-based radionuclide therapy was 67% (n = 22, n = 11 SDHx), and with first-line "cold" somatostatin analogs 100% (n = 6, n = 3 SDHx).

CONCLUSION

SSTR2 expression was independently associated with SDHB/SDHx mutations and metastatic disease. We confirm a high disease control rate of somatostatin receptor-based therapies in metastatic PPGLs.

Imaging of Small-Bowel Neuroendocrine Neoplasms: AJR Expert Panel Narrative Review

Neuroendocrine neoplasms (NENs) of the small bowel are typically slow-growing lesions that remain asymptomatic until reaching an advanced stage. Imaging modalities for lesion detection, staging, and follow-up in patients with known or suspected NEN include CT enterography, MR enterography, and PET/CT using a somatostatin receptor analog. FDG PET/CT may have a role in the evaluation of poorly differentiated NENs. Liver MRI, ideally with a hepatocyte-specific contrast agent, should be used in the evaluation of hepatic metastases. Imaging informs decisions regarding both surgical approaches and systematic therapy (specifically, peptide receptor radionuclide therapy). This AJR Expert Panel Narrative Review describes the multimodality imaging features of small-bowel NENs; explores the optimal imaging modalities for their diagnosis, staging, and follow-up; and discusses how imaging may be used to guide therapy.

Multimodality Imaging of Cardiac Paragangliomas

Paragangliomas are rare neuroendocrine tumors of extra-adrenal autonomic paraganglia origin. Paragangliomas rarely involve the heart, and they account for less than 1% of primary cardiac tumors. Most cardiac paragangliomas are incidentally detected at echocardiography or CT or during the workup of symptomatic patients with high catecholamine levels. Paragangliomas are typically located around the great vessels, coronary arteries (atrioventricular groove), or the atria, which can be explained by the tumor origin from the paraganglia and the distribution of the cardiac plexus. At MRI, cardiac paragangliomas typically have low to intermediate signal on T1-weighted images and high signal on T2-weighted images. The tumors are strongly vascularized, with high uptake on first-pass perfusion images and a heterogeneous pattern on late gadolinium enhancement images. Functional imaging is indicated for diagnostic confirmation and to screen for additional tumor locations or metastatic disease. Surgical excision is the only curative treatment. Cardiac CT angiography or invasive angiography should be performed preoperatively to precisely delineate tumor vascularization. In particular, its relation with the coronary arteries should be determined, as paragangliomas can be perfused by the coronary arteries, posing additional surgical challenges and the need for coronary revascularization. This imaging essay reviews the characteristics of paragangliomas and the use of multimodality imaging for diagnosis and treatment. Keywords: CT Angiography, Molecular Imaging, MR Imaging, PET/CT, Cardiac, Heart, Neoplasms-Primary © RSNA, 2023.

Paediatric phaeochromocytoma and paraganglioma: A clinical update

Paediatric phaeochromocytomas and paragangliomas (PPGLs), though rare tumours, are associated with significant disability and death in the most vulnerable of patients early in their lives. However, unlike cryptogenic and insidious disease states, the clinical presentation of paediatric patients with PPGLs can be rather overt, allowing early diagnosis, granted that salient findings are recognized. Additionally, with prompt and effective intervention, prognosis is favourable if timely intervention is implemented. For this reason, this review focuses on four exemplary paediatric cases, succinctly emphasizing the now state-of-the-art concepts in paediatric PPGL management.

A Case of Generalized, Unrelenting Sweating Resulting in Social Isolation for Over Two Decades

Pheochromocytoma, a rare neuroendocrine tumor, affects less than 1 in 100,000 people per year. Individuals with pheochromocytoma usually present with headache, diaphoresis, and tachycardia; however, diaphoresis occurs in less than half of the patients. Diaphoresis or chronic persistent hyperhidrosis can significantly impact patients' lives, leading to depression, anxiety, and social isolation, as in our case. We report a patient with chronic persistent sweating for over two decades as the predominant manifestation of pheochromocytoma and sympathetic overdrive, affecting her mental and social well-being. Importantly, we would like to demonstrate the significance of long-standing sweating, which can impact an individual's mental well-being and social life. Incorporating the Hyperhidrosis Disease Severity Measure-Axillary (HDSM-Ax) in the evaluation and management might be a relevant consideration. Pertinently, if medical measures and Botulinum toxin have failed to resolve excessive sweating, a thoracoscopic sympathetic block deserves consideration. Note that diaphoresis and hyperhidrosis, terms representing excessive sweating, will be used interchangeably.

Management of pheochromocytomas and paragangliomas: Review of current diagnosis and treatment options

Pheochromocytomas (PCCs) are rare neuroendocrine tumors derived from the chromaffin cells of the adrenal medulla. When these tumors have an extra-adrenal location, they are called paragangliomas (PGLs) and arise from sympathetic and parasympathetic ganglia, particularly of the para-aortic location. Up to 25% of PCCs/PGLs are associated with inherited genetic disorders. The majority of PCCs/PGLs exhibit indolent behavior. However, according to their affiliation to molecular clusters based on underlying genetic aberrations, their tumorigenesis, location, clinical symptomatology, and potential to metastasize are heterogenous. Thus, PCCs/PGLs are often associated with diagnostic difficulties. In recent years, extensive research revealed a broad genetic background and multiple signaling pathways leading to tumor development. Along with this, the diagnostic and therapeutic options were also expanded. In this review, we focus on the current knowledge and recent advancements in the diagnosis and treatment of PCCs/PGLs with respect to the underlying gene alterations while also discussing future perspectives in this field.

Clinical consensus guideline on the management of phaeochromocytoma and paraganglioma in patients harbouring germline SDHD pathogenic variants

Patients with germline SDHD pathogenic variants (encoding succinate dehydrogenase subunit D; ie, paraganglioma 1 syndrome) are predominantly affected by head and neck paragangliomas, which, in almost 20% of patients, might coexist with paragangliomas arising from other locations (eg, adrenal medulla, para-aortic, cardiac or thoracic, and pelvic). Given the higher risk of tumour multifocality and bilaterality for phaeochromocytomas and paragangliomas (PPGLs) because of SDHD pathogenic variants than for their sporadic and other genotypic counterparts, the management of patients with SDHD PPGLs is clinically complex in terms of imaging, treatment, and management options. Furthermore, locally aggressive disease can be discovered at a young age or late in the disease course, which presents challenges in balancing surgical intervention with various medical and radiotherapeutic approaches. The axiom-first, do no harm-should always be considered and an initial period of observation (ie, watchful waiting) is often appropriate to characterise tumour behaviour in patients with these pathogenic variants. These patients should be referred to specialised high-volume medical centres. This consensus guideline aims to help physicians with the clinical decision-making process when caring for patients with SDHD PPGLs.

Paragangliomas and Pheochromocytomas: Positron Emission Tomography/Computed Tomography Diagnosis and Therapy

Molecular imaging evaluation of pheochromocytomas and paragangliomas depends on multiple factors, such as localized versus metastatic disease, the genetic, and biochemical profile of tumors. Positron emission tomography/computed tomography (PET/CT) imaging of these tumors outperforms Meta-Iodo-Benzyl-Guanidine (MIBG) scintigraphy in most cases. A few PET radiotracers have been studied in evaluating these patients with somatostatin receptor PET imaging and have shown superior performance compared with other agents in most of these patients. 18F-fluorodeoxyglucose PET/CT imaging is useful in select patients, such as those with succinate dehydrogenase complex subunit B-associated disease. Treatment strategy depends on multiple factors and necessitates a multidisciplinary approach.

Paraganglioma in a Young Adult Female Patient: A Case Report

Paragangliomas are catecholamine-secreting neuroendocrine tumors that originate from the chromaffin cells of the sympathetic ganglia. Roughly 10% of paragangliomas are malignant, resulting in a rare occurrence of 90-95 cases per 400 million people. Herein, we report a case of a 29-year-old female patient who presented with nausea, vomiting, and bloating and was found to have a large left retroperitoneal tumor upon imaging. The tumor was successfully removed, and subsequent histological analysis was compatible with the presence of a paraganglioma. This case serves as a reminder that despite its rarity, paragangliomas should never be dismissed as a differential diagnosis if correlating symptoms and diagnostic findings are consistent with that of paraganglioma etiology.

Same-day comparative protocol PET/CT-PET/MRI [68 Ga]Ga-DOTA-TOC in paragangliomas and pheochromocytomas: an approach to personalized medicine

BACKGROUND

PET/MRI is an emerging imaging modality which enables the evaluation and quantification of biochemical processes in tissues, complemented with accurate anatomical information and low radiation exposure. In the framework of theragnosis, PET/MRI is of special interest due to its ability to delineate small lesions, adequately quantify them, and therefore to plan targeted therapies. The aim of this study was to validate the diagnostic performance of [⁶⁸ Ga]Ga-DOTA-TOC PET/MRI compared to PET/CT in advanced disease paragangliomas and pheochromocytomas (PGGLs) to assess in which clinical settings, PET/MRI may have a greater diagnostic yield.

METHODS

We performed a same-day protocol with consecutive acquisition of a PET/CT and a PET/MRI after a single [⁶⁸ Ga]Ga-DOTA-TOC injection in 25 patients. Intermodality agreement, Krenning Score (KS), SUVmax (Standard Uptake Value), target-to-liver-ratio (TLR), clinical setting, location, and size were assessed.

RESULTS

The diagnostic accuracy with PET/MRI increased by 14.6% compared to PET/CT especially in bone and liver locations (mean size of new lesions was 3.73 mm). PET/MRI revealed a higher overall lesion uptake than PET/CT (TLR 4.12 vs 2.44) and implied an upward elevation of the KS in up to 60% of patients. The KS changed in 30.4% of the evaluated lesions (mean size 11.89 mm), in 18.4% of the lesions it increased from KS 2 on PET/CT to a KS ≥ 3 on PET/MRI and 24.96% of the lesions per patient with multifocal disease displayed a KS ≥ 3 on PET/MR, that were not detected or showed lower KS on PET/CT. In 12% of patients, PET/MRI modified clinical management.

CONCLUSIONS

PET/MRI showed minor advantages over conventional PET/CT in the detection of new lesions but increased the intensity of SSRs expression in a significant number of them, opening the door to select which patients and clinical settings can benefit from performing PET/MRI.

18 F-MFBG PET/CT Is an Effective Alternative of 68 Ga-DOTATATE PET/CT in the Evaluation of Metastatic Pheochromocytoma and Paraganglioma

PURPOSE

The current guidelines state that the functional imaging choice in the evaluation of metastatic pheochromocytoma and paraganglioma (PPGL) is 68 Ga-DOTATATE PET/CT. 18 F-meta-fluorobenzylguanidine ( 18 F-MFBG) is a new PET tracer and an analog of meta-iodobenzylguanidine (MIBG). This study aimed to compare 18 F-MFBG and 68 Ga-DOTATATE PET/CT in patients with metastatic PPGL.

PATIENTS AND METHODS

Twenty-eight patients with known metastatic PPGL were prospectively recruited for this study. All patients underwent both 18 F-MFBG and 68 Ga-DOTATATE PET/CT studies within 1 week. Lesion numbers detected were compared between these 2 studies.

RESULTS

18 F-MFBG PET/CT was positive for detecting metastases in all patients, whereas positive results of 68 Ga-DOTATATE PET/CT were in 27 (96.4%) patients. A total of 686 foci of metastatic lesions were detected by both 18 F-MFBG and 68 Ga-DOTATATE imaging. In addition, 33 foci of abnormal activity were only detected by 18 F-MFBG, whereas 16 foci were only shown on 68 Ga-DOTATATE PET/CT.

CONCLUSIONS

Our data suggest that 18 F-MFBG PET/CT is an effective imaging method in the evaluation of metastatic PPGL and could be alternative of 68 Ga-DOTATATE PET/CT in this clinical setting.

New Biology of Pheochromocytoma and Paraganglioma

Pheochromocytomas and paragangliomas continue to be defined by significant morbidity and mortality despite their several recent advances in diagnosis, localization, and management. These adverse outcomes are largely related to mass effect as well as catecholamine-induced hypertension, tachyarrhythmias and consequent target organ damage, acute coronary syndromes, and strokes (ischemic and hemorrhagic stroke). Thus, a proper understanding of the physiology and pathophysiology of these tumors and recent advances are essential to affording optimal care. These major developments largely include a redefinition of metastatic behavior, a novel clinical categorization of these tumors into 3 genetic clusters, and an enhanced understanding of catecholamine metabolism and consequent specific biochemical phenotypes. Current advances in imaging of these tumors are shifting the paradigm from poorly specific anatomical modalities to more precise characterization of these tumors using the advent and development of functional imaging modalities. Furthermore, recent advances have revealed new molecular events in these tumors that are linked to their genetic landscape and, therefore, provide new therapeutic platforms. A few of these prospective therapies translated into new clinical trials, especially for patients with metastatic or inoperable tumors. Finally, outcomes are ever-improving as patients are cared for at centers with cumulative experience and well-established multidisciplinary tumor boards. In parallel, these centers have supported national and international collaborative efforts and worldwide clinical trials. These concerted efforts have led to improved guidelines collaboratively developed by healthcare professionals with a growing expertise in these tumors and consequently improving detection, prevention, and identification of genetic susceptibility genes in these patients.

A Rare Case of Thoracoabdominal Paraganglioma: A Case Report and Literature Review

Pheochromocytomas and paragangliomas are rare neuroendocrine tumors. Pheochromocytomas are derived from chromaffin cells of the adrenal medulla, while paragangliomas arise from the extra-adrenal autonomic paraganglia. Paragangliomas can derive from either parasympathetic or sympathetic paraganglia. The majority of parasympathetic ganglia-derived paragangliomas are nonfunctional and symptoms arise from mass effect, while sympathetic paragangliomas are frequently functional and present with symptoms that result from catecholamine hypersecretion. Here, we present the case of a 19-year-old female with hypertension whose biochemical tests revealed elevated plasma and urinary levels of norepinephrine and normetanephrine. Imaging studies showed a left paravertebral mass which was surgically removed. Histopathology confirmed a paraganglioma. Total surgical resection remains the gold-standard treatment and a cure can be achieved; however, all tumors may harbor malignant potential, and a long-term biochemical and imaging follow-up is required in all patients. Screening for genetic germline mutations may be helpful in identifying patients with a higher risk of recurrence or of developing other primary tumors.

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.

Role of imaging test with radionuclides in the diagnosis and treatment of pheochromocytomas and paragangliomas

Radionuclide imaging tests with [¹²³I] Metaiodobenzylguanidine (MIBG), [¹⁸F] -fluorodeoxyglucose, [¹⁸F]-fluorodopa, or ⁶⁸Ga-DOTA(0)-Tyr(3)-octreotate are useful for the diagnosis, staging and follow-up of pheochromocytomas (PHEOs) and paragangliomas (PGLs) (PPGLs). In addition to their ability to detect and localize the disease, they allow a better molecular characterization of the tumours, which is useful for planning targeted therapy with iodine-131 (¹³¹I) -labelled MIBG or with peptide receptor radionuclide therapy (PRRT) with [¹⁷⁷Lu]-labelled DOTATATE or other related agents in patients with metastatic disease. In this review we detail the main characteristics of the radiopharmaceuticals used in the functional study of PPGLs and the role of nuclear medicine tests for initial evaluation, staging, selection of patients for targeted molecular therapy, and radiation therapy planning. It also offers a series of practical recommendations regarding the functional imaging according to the different clinical and genetic scenarios in which PPGLs occur, and on the indications and efficacy of therapy with [¹³¹I]-MIBG and ¹⁷⁷Lu-DOTATATE.

Bone Metastasis of Glomus Caroticum Demonstrated on 68Ga-DOTATATE PET/CT

ABSTRACT

A 71-year-old man who was diagnosed with carotid body paraganglioma was referred to 68Ga-DOTATATE PET/CT for primary evaluation, which revealed unknown bony metastasis with intense 68Ga-DOTATATE uptake. Head and neck paragangliomas are rare neuroendocrine tumors, with a 10% of malignancy rate, and identification of metastatic sites is important in staging and prognosis of the disease. We aimed to highlight the impact of 68Ga-DOTATATE PET/CT on patient management, especially for equivocal lesions, as in our case.

Molecular Imaging of Neuroendocrine Neoplasms

The key for molecular imaging is the use of a radiotracer with a radioactive and a functional component. While the functional component targets a specific feature of the tumor, the radioactive component makes the target visible. Neuroendocrine neoplasms (NEN) are a diverse group of rare tumors that arise from neuroendocrine cells found mainly in the gastroenteropancreatic system, lung, thyroid, and adrenal glands. They are characterized by the expression of specific hormone receptors on the tumor cell surface, which makes them ideal targets for radiolabeled peptides. The most commonly expressed hormone receptors on NEN cells are the somatostatin receptors. They can be targeted for molecular imaging with various radiolabeled somatostatin analogs, but also with somatostatin antagonists, which have shown improved imaging quality. 18F-DOPA imaging has become a second-line imaging modality in NENs, with the exception of the evaluation of advanced medullary thyroid carcinoma. Alternatives for NENs with insufficient somatostatin receptor expression due to poor differentiation involve targeting glucose metabolism, which can also be used for prognosis. For the localization of the often-small insulinoma, glucagon-like peptide-1 (GLP-1) receptor imaging has become the new standard. Other alternatives involve metaiodobenzylguanidine and the molecular target C-X-C motif chemokine receptor-4. In addition, new radiopeptides targeting the fibroblast activation protein, the glucose-dependent insulinotropic polypeptide receptor and cholecystokinin-2 receptors have been identified in NENs and await further evaluation. This mini-review aims to provide an overview of the major molecular imaging modalities currently used in the field of NENs, and also to provide an outlook on future developments.

PET-CT in Clinical Adult Oncology-VI. Primary Cutaneous Cancer, Sarcomas and Neuroendocrine Tumors

PET-CT is an advanced imaging modality with many oncologic applications, including staging, therapeutic assessment, restaging and surveillance for recurrence. The goal of this series of six review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for specific oncologic indications, the potential pitfalls and nuances that characterize these applications, and guidelines for image interpretation. Tumor-specific clinical information and representative PET-CT images are provided. The current, sixth article in this series addresses PET-CT in an evaluation of aggressive cutaneous malignancies, sarcomas and neuroendocrine tumors. A discussion of the role of FDG PET for all types of tumors in these categories is beyond the scope of this review. Rather, this article focuses on the most common malignancies in adult patients encountered in clinical practice. It also focuses on Food and Drug Agency (FDA)-approved and clinically available radiopharmaceuticals rather than research tracers or those requiring a local cyclotron. This information will serve as a guide to primary providers for the appropriate role of PET-CT in managing patients with cutaneous malignancies, sarcomas and neuroendocrine tumors. The nuances of PET-CT interpretation as a practical guide for imaging providers, including radiologists, nuclear medicine physicians and their trainees, are also addressed.

68Ga-DOTATATE PET/CT Scan as a Valuable Tool for Diagnosis and Staging of the Rare Entity of Tracheal Paragangliomas

ABSTRACT

Primary paraganglioma of the trachea is a rare differential among more common tracheal masses. Definitive diagnosis of tracheal masses is obtained via endoscopic biopsy. Utilization of 68Ga-DOTATATE PET/CT is valuable in the workup of these lesions as paragangliomas would have significantly higher radiotracer uptake compared with the more common squamous cell and adenoid cystic carcinomas. This is particularly important in tracheal paragangliomas, which are typically friable and hypervascular with higher risk of significant bleeding on biopsy. In addition, 68Ga-DOTATATE PET/CT can be used to evaluate for local invasion and metastatic disease as a 1-step imaging modality.

Metastatic pheochromocytomas and paragangliomas: where are we?

Pheochromocytomas and paragangliomas (PPGLs) can metastasize in approximately 15-20% of cases. This review discusses the available evidence on the biology and treatment of metastatic PPGLs. Chemotherapy is the first-line treatment option for this evolving and symptomatic disease. In patients with high MIBG uptake and positive PETGa-68, radiometabolic treatment may be considered. The efficacy of sunitinib has been shown in observational studies, and pembrolizumab has been evaluated in phase II clinical studies, while other agents investigated in this setting are anti-angiogenic drugs cabozantinib, dovitinib, axitinib and lenvatinib. As these agents' efficacy and safety data, alone or in combination, are scant and based on few treated patients, enrollment in clinical trials is mandatory. Future therapeutic options may be represented by DNA repair system inhibitors (such as olaparib), HIF2 inhibitors and immunotherapy.

Management of Pheochromocytomas and Paragangliomas: A Case-Based Review of Clinical Aspects and Perspectives

Paraganglioma and pheochromocytoma are rare medical conditions. Thus, there are still a small number of studies, clinical trials, and evidence-based data in this field. This makes clinical decisions more difficult. In this study, we present a case report enriched with a short review of available essential clinical data, indicating the need for constant metoxycatecholamine level observation and a proper diagnostic imaging approach, especially in terms of ongoing pandemics. Our research also provides a summary of the molecular background of these diseases, indicating their future role in clinical management. We analyzed the ClinicalTrials.gov dataset in order to show future perspectives. In this paper, the use of the PET-CT before MRI or CT is proposed in specific cases during diagnosis processes contrary to the guidelines. PET-CT may be as effective as standard procedures and may provide a faster diagnosis, which is important in periods with more difficult access to health care, such as during the COVID-19 pandemic.

Head and Neck Paragangliomas: An Update on the Molecular Classification, State-of-the-Art Imaging, and Management Recommendations

Paragangliomas are neuroendocrine tumors that derive from paraganglia of the autonomic nervous system, with the majority of parasympathetic paragangliomas arising in the head and neck. More than one-third of all paragangliomas are hereditary, reflecting the strong genetic predisposition of these tumors. The molecular basis of paragangliomas has been investigated extensively in the past couple of decades, leading to the discovery of several molecular clusters and more than 20 well-characterized driver genes (somatic and hereditary), which are more than are known for any other endocrine tumor. Head and neck paragangliomas are largely related to the pseudohypoxia cluster and have been previously excluded from most molecular profiling studies. This review article introduces the molecular classification of paragangliomas, with a focus on head and neck paragangliomas, and discusses its impact on the management of these tumors. Genetic testing is now recommended for all patients with paragangliomas to provide screening and surveillance recommendations for patients and relatives. While CT and MRI provide excellent anatomic characterization of paragangliomas, gallium 68 tetraazacyclododecane tetraacetic acid-octreotate (ie, ⁶⁸Ga-DOTATATE) has superior sensitivity and is recommended as first-line imaging in patients with head and neck paragangliomas with concern for multifocal and metastatic disease, patients with known multifocal and metastatic disease, and in candidates for targeted peptide-receptor therapy. Keywords: Molecular Imaging, MR Perfusion, MR Spectroscopy, Neuro-Oncology, PET/CT, SPECT/CT, Head/Neck, Genetic Defects © RSNA, 2022.

Wide Variability in Catecholamine Levels From Adrenal Venous Sampling in Primary Aldosteronism

INTRODUCTION

While adrenal venous sampling (AVS) differentiates between the unilateral and bilateral disease in patients with primary aldosteronism (PA), it is unknown if AVS can determine laterality of pheochromocytoma in patients with bilateral adrenal masses. This study analyzes adrenal vein (AV) epinephrine and norepinephrine levels in nonpheochromocytoma patients to determine the "normal" range.

MATERIALS AND METHODS

We reviewed patients who underwent AVS for PA between 2009 and 2019 at a single institution; pheochromocytoma was excluded. Aldosterone, cortisol, epinephrine, and norepinephrine levels were obtained from the inferior vena cava (IVC), left adrenal vein (LAV), and right adrenal vein (RAV). Successful AV cannulation was defined by an AV/IVC cortisol ratio of ≥3:1 or an AV epinephrine level ≥364 pg/mL. Plasma measurements (pg/mL) are median values with interquartile ranges; normal ranges for epinephrine and norepinephrine are 10-200 pg/mL and 80-520 pg/mL, respectively.

RESULTS

AVS was performed in 172 patients in 405 AVs (173 LAV and 232 RAV). Median epinephrine levels were IVC = 19 (14 and 34), LAV = 3811 (1870 and 6915), and RAV = 2897 (1500 and 5288). Median norepinephrine levels were IVC = 325 (186 and 479), LAV = 1450 (896 and 2050), and RAV = 786 (436 and 1582). There was a difference between LAV and RAV epinephrine levels (P = 0.024) and between LAV and RAV norepinephrine (P = 0.002) levels.

CONCLUSIONS

This extensive experience with AVS demonstrated a wide range of "normal" AV catecholamine levels in patients without pheochromocytoma, which suggests that the utility of AVS to determine disease laterality in patients with pheochromocytoma and bilateral adrenal nodules is likely to be limited.