Role of DOTATATE-PET/CT in preoperative assessment of phaeochromocytoma and paragangliomas

Diagnostic pitfalls in [68Ga]Ga-DOTATATE PET/CT imaging: a systematic review

[68Ga]Ga-DOTA-Tyr3-octreotate ([68Ga]Ga-DOTATATE) is an established somatostatin receptor imaging agent that has demonstrated superior efficacy in visualizing neuroendocrine tumors (NETs) and meningiomas compared with traditional [111In]In-octreotide imaging. Despite its enhanced affinity and sensitivity, [68Ga]Ga-DOTATATE imaging is not without challenges. To date, numerous diagnostic pitfalls and false-positive findings have been reported. This systematic review investigates the currently recognized diagnostic pitfalls in [68Ga]Ga-DOTATATE positron imaging. A systematic literature search was conducted using PubMed, Scopus, and Web of Science databases, with the most recent update on 8 March 2024. Two authors screened the titles and abstracts of retrieved articles and selected studies based on predefined inclusion and exclusion criteria. Qualitative analysis of 70 included research articles, encompassing 199 patients, identified 234 diagnostic pitfalls. Malignant neoplastic etiologies predominated, constituting 56% of pitfalls, followed by nononcologic pitfalls (32.1%), and benign oncologic tumors (11.9%). Anatomically, the head and neck region was the most frequent site for pitfalls (35.5%), followed by the musculoskeletal system (27.4%), abdomen (17.5%), and chest (16.6%). Pelvic-related pitfalls were least common, accounting for only 3% of cases. This study details potential diagnostic pitfalls, predominantly occurring in the head-neck regions - primary sites for meningiomas and paragangliomas. Understanding these diagnostic pitfalls is crucial for accurate diagnosis. Moreover, recognizing these diagnostic pitfalls may lead to novel applications of [68Ga]Ga-DOTATATE beyond its conventional use in NETs and meningiomas, potentially expanding its diagnostic utility.

Pheochromocytoma and Paragangliomas: Current Management Strategies

Pheochromocytomas and paragangliomas are rare neuroendocrine tumors with complex clinical presentations and potential for malignancy. This review highlights advancements in biochemical testing, imaging, genetic counseling, and surgical management, which have improved diagnostic accuracy and patient outcomes. Minimally invasive surgical approaches are commonly preferred, but open surgery remains necessary for larger or complex tumors. Emerging treatments in the metastatic stage, such as targeted therapies and radioligand therapy, show promise. However, access to advanced imaging and treatment options varies globally, underscoring the need for multidisciplinary care and further research to optimize management strategies.

Somatostatin Receptor 2 Negative Pheochromocytoma Masked by Normal Adrenal Gland on Gallium-68 DOTATATE

Background/Objective

Gallium-68 DOTATATE (68Ga-DOTATATE) positron emission tomography/computed tomography (CT) is a somatostatin receptor (SSTR)-based imaging with high sensitivity that can be used for detection of pheochromocytomas and paragangliomas. We report a pheochromocytoma with negative SSTR2 expression and low uptake on 68Ga-DOTATATE, whose detection was masked by the uptake of normal adrenal tissue.

Case Report

A 50-year-old man presented with a right adrenal incidentaloma. He had mildly elevated plasma normetanephrine levels of 194 pg/mL (ref. 0-145 pg/mL). Adrenal CT scan showed a right 1.9-cm lesion with unenhanced attenuation of 38 Hounsfield units. 68Ga-DOTATATE showed a 1.9-cm right adrenal lesion and reported diffuse uptake in the adrenal glands, with maximum standardized uptake value (SUVmax) of 17.23 on the right and SUVmax of 22.78 on the left. After a 2-year interval, plasma normetanephrine level increased to 420 pg/mL (ref. 0-136.8 pg/mL). Adrenal CT scan showed the right adrenal lesion increased in size to 2.6 cm. He underwent right adrenalectomy, and pathology reported a 2.3-cm pheochromocytoma. Subsequent review of the initial 68Ga-DOTATATE identified the pheochromocytoma as a photopenic area in the right adrenal gland with 7.73 SUVmax. Tissue staining was negative for SSTR2 expression. Genetic testing was negative for pheochromocytoma syndromes.

Discussion

Although 68Ga-DOTATATE has strong affinity for SSTR2, some pheochromocytomas have low expression of SSTR2. The negative SSTR2 expression, small lesion size, and background uptake of the adrenal gland can affect the detection of pheochromocytoma.

Conclusion

68Ga-DOTATATE may have limitations when evaluating small pheochromocytomas or other neuroendocrine tumors with low SSTR2 expression.

Castleman disease presenting as DOTATATE-positive retroperitoneal mass

Castleman disease is a rare, heterogeneous group of lymphoproliferative disorders whose imaging characteristics can resemble malignancy. We present a case of a patient who initially presented with intermittent hypertension, palpitations, and chest pain. Despite a negative biochemical workup, CT imaging revealed a left retroperitoneal mass intimately associated with the left adrenal gland with 68Ga-DOTATATE positron emission tomography-computed tomography (PET/CT) detecting uptake in the mass as well as several left para-aortic lymph nodes and bone lesions. Based on the imaging findings, the patient was taken to the operating room for resection of what was presumed to be a metastatic neuroendocrine tumour. However, the diagnosis on histopathological examination was hyaline-vascular Castleman disease. While DOTATATE PET/CT has high sensitivity and specificity for neuroendocrine tumours (NETs), this case report highlights that non-neuroendocrine pathology may result in DOTATATE uptake, and that Castleman disease should be considered when encountering DOTATATE-positive masses on imaging.

Diagnostic Performance of [18 F] FDOPA PET/CT and Other Tracers in Pheochromocytoma: A Meta-Analysis

RATIONALE AND OBJECTIVES

PET-CT is extensively used in the diagnosis of pheochromocytoma (PHEO). However, various PET-CT tracers are recommended for the diagnosis of PHEO. Therefore, this study evaluated the diagnostic performance of all tracers currently used in the PET-CT detection of PHEO.

METHODS

Studies were retrieved from PubMed, Web of Science, Embase, and Cochrane Library from inception to Feb. 7, 2024. The studies were screened according to the eligibility criteria and the data were extracted. Quality of the included studies was evaluated by the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic (sROC) curve (AUC) were pooled in Stata 15, and diagnostic accuracy was pooled in R 4.3.3.

RESULTS

Sixteen studies were included in the meta-analysis. The sensitivity and specificity of [18 F]FDOPA PET/CT for initial PHEO diagnosis were 97% (95% CI: 91%-99%, I2 = 46.14%, p > 0.01) and 94% (95% CI: 86%-98%, I2 = 87.90%, p < 0.01), respectively. The AUC was 0.99 (95% CI: 0.98-1.00). The diagnostic accuracy of [18 F]FDOPA PET/CT was 98.9% (95% CI: 95%-100%) for PHEO patients and 89.7% (95% CI: 85.4%-92.8%) for PHEO lesions. [68Ga]DOTATATE PET/CT had a diagnostic accuracy of 86.9% (95% CI: 78.2%-93.9%) for PHEO and 87.5% (95% CI: 70.3%-95.4%) for PHEO lesions. FDG PET/CT had a diagnostic accuracy of 85.2% (95% CI: 73.6%-94.1%) for PHEO and 86.8% (95% CI: 73%-94.2%) for PHEO lesions. [68Ga]DOTANOC PET/CT had a diagnostic accuracy of 79.3% (95% CI: 49.2%-98.3%) for PHEO.

CONCLUSIONS

In general, PET/CT demonstrates superior performance in the diagnosis of PHEO. In addition, [18 F]FDOPA PET/CT has the best diagnostic performance in PHEO compared with other tracers. Given the limited research on other PET/CT tracers and the potential constraints on their widespread use, additional multicenter and multiregional studies are warranted to further evaluate their diagnostic performance and provide recommendations for clinical use.

Positron Emission Tomography Imaging of Pheochromocytoma and Paraganglioma-18F-FDOPA vs Somatostatin Analogues

CONTEXT

Functional imaging with positron emission tomography (PET) scans is an essential part of the diagnostic workup for pheochromocytoma and paraganglioma (PPGL). The purpose of this review is to (1) provide a brief overview of functional imaging for PPGL, (2) summarize selected present and older guideline and review recommendations, and (3) conduct a literature review on the diagnostic performance of the most used PET tracers for PPGL.

EVIDENCE ACQUISITION

We conducted a systematic literature search in PubMed from January 2004 to August 2024 with the search string ("Pheochromocytoma" OR "Paraganglioma") AND ("Positron Emission Tomography" OR "Radionuclide Imaging" OR ("PET" AND ("FDG" OR "DOTATOC" OR "DOTANOC" OR "DOTATATE" OR "DOPA" OR "FDOPA"))). Studies involving PET scans of at least 20 individuals with PPGL or at least 5 individuals in a rare, well-defined subgroup of PPGL (eg, sympathetic or head-neck paragangliomas and specific pathogenic variants) were included.

EVIDENCE SYNTHESIS

Seventy studies were identified of which 21 were head-to-head comparisons of at least 2 different PET tracers [18F-fluorodihydroxyphenylalanine, fluorodihydroxyphenylalanine positron emission tomography (18F-FDOPA), 68Ga-DOTA-conjugated somatostatin analogues, 68Ga-DOTA-conjugated somatostatin analogue positron emission tomography (68Ga-SSA), and 18F-fluorodeoxyglucose]. 18F-FDOPA had higher sensitivity for pheochromocytoma compared to 68Ga-SSA and equal sensitivity for metastatic pheochromocytoma. 18F-FDOPA and 68Ga-SSA had similar sensitivity for primary non-succinate dehydrogenase subunits (SDHx) sympathetic and head-neck paraganglioma. However, 68Ga-SSA had higher sensitivity for metastatic sympathetic and head-neck paraganglioma and for SDHx-related paraganglioma.

CONCLUSION

18F-FDOPA and 68Ga-SSA PET are both sensitive for localizing PPGL. However, 18F-FDOPA is the most sensitive for detecting pheochromocytoma, while 68Ga-SSA is superior to 18F-FDOPA for metastatic sympathetic and head-neck paraganglioma and SDHx-related paraganglioma.

Pheochromocytoma in MEN2

Pheochromocytomas (PCs) are rare neuroendocrine tumors found in 20-50% of MEN2 patients. MEN2-related PCs are more often bilateral, identified at a younger age and have a low metastatic potential. They secrete epinephrine as the predominant catecholamine, along with its metabolite metanephrine, and lesser amounts of norepinephrine and normetanephrine. The advent of molecular diagnostic tools has enhanced the identification and stratification of these tumors, revealing a strong genotype-phenotype correlation which is crucial for screening and managing patients. Evaluation involves a combination of structural (CT/MRI) and functional imaging. MIBG remains helpful for PC assessment but novel PET ligands (18F-DOPA, 68Ga-DOTATATE, 18F-FDG) aid in the detection of extra-adrenal paragangliomas, recurrence, and metastatic disease. The treatment paradigm has shifted toward personalized medicine, incorporating genetic insights to tailor interventions, particularly surgical approaches and novel therapeutics such as radiolabeling of somatostatin analogs with lutetium and tyrosine kinase inhibitors.

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.

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.

Cascaded nanozyme-based high-throughput microfluidic device integrating with glucometer and smartphone for point-of-care pheochromocytoma diagnosis

The development of point-of-care (POC) diagnostics devices for circulating tumor cells (CTCs) detection plays an important role in the early diagnosis of pheochromocytoma (PCC), especially in a low-resource setting. To further realize the rapid, portable, and high-throughput detection of CTCs, an Au@CuMOF cascade enzyme-based microfluidic device for instant point-of-care detection of CTCs was constructed by combining a smartphone application and a commercial portable glucose meter (PGM). In this microfluidic system, DOTA and norepinephrine (NE) modified Au@CuMOF signal probes and Fe3O4@SiO2 capture probes were used for the dual recognition and capture of rare PCC-CTCs. Then, the targeted binding of the Au@CuMOF cascade nanozymes to the CTCs endowed the cellular complexes with multienzyme mimetic activities (i.e., glucose oxidase-like and peroxidase-like activity) to catalyze glucose reduction as signal output for colorimetric and personal glucose meter (PGM) dual-mode detection of CTCs. The developed method has a linear range of 4 to 105 cells mL-1 and a detection limit of 3 cells mL-1. This method allows the simultaneous detection of six samples and demonstrates good applicability for CTCs detection in whole blood samples. More importantly, the combination of PGM, smartphone app and array microfluidic chips enables the rapid, portable, and high-throughput diagnoses of PCC, and providing provide a convenient and reliable alternative to traditional liquid biopsy diagnosis of various cancers.

Clinical Characteristics of Adrenal Hemangioma

Objective

Adrenal hemangioma (AH) is a rare, benign adrenal tumor often detected incidentally by imaging. This retrospective study aimed to investigate the clinical characteristics of AH, including clinical and diagnostic imaging features, to improve the recognition and understanding of AH.

Methods

We retrospectively analyzed the medical records of patients diagnosed with AH at Peking Union Medical College Hospital between 2008 and 2022. Clinical manifestations, adrenal hormone levels, imaging findings, treatment approaches, and pathological results were collected and analyzed.

Results

Of the 7140 adrenal tumor patients, 40 (0.56%) had AH confirmed postoperatively. The mean age at diagnosis was 53.9 years, with a female predominance. Most (70%) were asymptomatic and diagnosed incidentally. Misdiagnosis before surgery was common, most frequently as pheochromocytoma. Imaging characteristics, especially enhanced computed tomography, revealed distinct features based on tumor size. Surgery was the main treatment, with laparoscopic adrenalectomy preferred.

Conclusion

This study elucidates the clinical characteristics of AH, including demographics, diagnostic challenges, and imaging features. AH often presents incidentally and is frequently misdiagnosed preoperatively. Recognizing distinct imaging characteristics and appropriate surgical management can enable accurate diagnosis and optimal treatment.

The Clinical Utility of Gallium-68-DOTATATE Positron Emission Tomography Scanning in Medullary Thyroid Cancer

OBJECTIVE

Somatostatin receptor (SST) functional imaging with positron emission tomography (PET)/computed tomography (CT) has broadened the diagnostic and staging capabilities for medullary thyroid cancer (MTC). Gallium-68 (68Ga)-DOTA-conjugated peptide (Tyr3)-octreotate (DOTATATE) is a radiotracer with a high affinity for type 2 SSTs expressed in several, but not all, MTCs. The utility of 68Ga-DOTATATE PET/CT and 18fluorine-labeled fluoro-2-deoxy-D-glucose (18F-FDG)-PET/CT imaging in predicting MTC prognosis is also unknown.

METHODS

In this single-center retrospective study, 103 of patients with MTC underwent assessment of SST2 and SST5 immunohistochemistry (IHC). A subgroup of 37 patients received 68Ga-DOTATATE PET/CT imaging, and 13 received contemporaneous 18F-FDG-PET/CT imaging. The maximum standardized uptake value (SUV), mean SUV, metabolic tumor volume, and total lesion activity (TLA) were assessed.

RESULTS

Forty-two patients (41%) demonstrated positive expression of SST2, and 45 (44%) had a positive SST5 IHC result. Seventeen patients (17%) expressed both SST2 and SST5. No survival advantage was identified with SST2 or SST5 IHC positivity. No correlation was noted between the maximum SUV, mean SUV, metabolic tumor volume, or TLA and SST2 and/or SST5 expression by IHC. Shorter survival was associated with a TLA of >20 (P = .04). A RET-negative status also appeared to have shorter survival, although this may be because the small numbers did not reach statistical significance (P = .12).

CONCLUSION

Assessment of TLA from 68Ga-DOTATATE PET/CT may predict survival. SST2 IHC was not correlated with 68Ga-DOTATATE avidity. Metastatic disease may be optimally assessed by concurrent 18F-FDG and 68Ga-DOTATATE imaging.

[18F]FDOPA PET/CT is superior to [68Ga]DOTATOC PET/CT in diagnostic imaging of pheochromocytoma

BACKGROUND

Both [18F]FDOPA (FDOPA) and [68Ga]DOTATOC PET/CT (DOTATOC) are widely used for detection of pheochromocytomas/paraganglioma (PPGL). However, direct comparisons of the performance of the two tracers are only available in small series. We conducted a retrospective comparative analysis of FDOPA and DOTATOC to assess their sensitivity and accuracy in detecting PPGL when administered based on suspicion of PPGL. We consecutively included patients referred on suspicion of PPGL or PPGL recurrence who were scanned with both FDOPA and DOTATOC. Both scans were reviewed retrospectively by two experienced observers, who were blinded to the final diagnosis. The assessment was made both visually and quantitatively. The final diagnosis was primarily based on pathology.

RESULTS

In total, 113 patients were included (97 suspected of primary PPGL and 16 suspected of recurrence). Of the 97 patients, 51 had pheochromocytomas (PCC) (in total 55 lesions) and 6 had paragangliomas (PGL) (in total 7 lesions). FDOPA detected and correctly localized all 55 PCC, while DOTATOC only detected 25 (sensitivity 100% vs. 49%, p < 0.0001; specificity 95% vs. 98%, p = 1.00). The negative predictive value (100% vs. 63%, p < 0.001) and diagnostic accuracy (98% vs. 70%, p < 0.01) were higher for FDOPA compared to DOTATOC. FDOPA identified 6 of 6 patients with hormone producing PGL, of which one was negative on DOTATOC. Diagnostic performances of FDOPA and DOTATOC were similar in the 16 patients with previous PPGL suspected of recurrence.

CONCLUSIONS

FDOPA is superior to DOTATOC for localization of PCC. In contrast to DOTATOC, FDOPA also identified all PGL but with a limited number of patient cases.

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.

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.

An Appraisal and Update of Fluorodeoxyglucose and Non-Fluorodeoxyglucose-PET Tracers in Thyroid and Non-Thyroid Endocrine Neoplasms

Endocrine neoplasms and malignancies are a diverse group of tumors with varied clinical, histopathologic, and functional features. These tumors vary from sporadic to hereditary, isolated entities to multiple neoplastic syndromes, functioning and non functioning tumors, unifocal locally invasive, and advanced to multifocal tumors with disseminated distant metastases. The presence of various specific biomarkers and specific receptor targets serves as valuable tools for diagnosis, prognosis, and management. PET-CT with FDG and a multitude of novel and specific radiotracers towards specific therapeutic targets mandates personalization of their use, so as to ensure maximum clinical benefit in the management of these neoplasms.

Subclinical phaeochromocytoma: a diagnostic and management challenge

There is a paradigm shift in the detection of phaeochromocytomas with more being identified as adrenal 'incidentalomas'. While majority of these individuals are asymptomatic, they are nevertheless at risk of subtle cardiovascular dysfunction and phaeochromocytoma crises. Therefore, early resection of phaeochromocytomas, even if subclinical, is recommended. However, the perioperative management can be challenging as the normotension can limit the initiation and titration of alpha-blockade. We present a man in his 60s with a subclinical phaeochromocytoma, discuss the evaluation of an incidentally discovered adrenal nodule, as well as the practical considerations in the perioperative management.

Personalized Management of Pheochromocytoma and Paraganglioma

Pheochromocytomas/paragangliomas are characterized by a unique molecular landscape that allows their assignment to clusters based on underlying genetic alterations. With around 30% to 35% of Caucasian patients (a lower percentage in the Chinese population) showing germline mutations in susceptibility genes, pheochromocytomas/paragangliomas have the highest rate of heritability among all tumors. A further 35% to 40% of Caucasian patients (a higher percentage in the Chinese population) are affected by somatic driver mutations. Thus, around 70% of all patients with pheochromocytoma/paraganglioma can be assigned to 1 of 3 main molecular clusters with different phenotypes and clinical behavior. Krebs cycle/VHL/EPAS1-related cluster 1 tumors tend to a noradrenergic biochemical phenotype and require very close follow-up due to the risk of metastasis and recurrence. In contrast, kinase signaling-related cluster 2 tumors are characterized by an adrenergic phenotype and episodic symptoms, with generally a less aggressive course. The clinical correlates of patients with Wnt signaling-related cluster 3 tumors are currently poorly described, but aggressive behavior seems likely. In this review, we explore and explain why cluster-specific (personalized) management of pheochromocytoma/paraganglioma is essential to ascertain clinical behavior and prognosis, guide individual diagnostic procedures (biochemical interpretation, choice of the most sensitive imaging modalities), and provide personalized management and follow-up. Although cluster-specific therapy of inoperable/metastatic disease has not yet entered routine clinical practice, we suggest that informed personalized genetic-driven treatment should be implemented as a logical next step. This review amalgamates published guidelines and expert views within each cluster for a coherent individualized patient management plan.

Sporadic Primary Pheochromocytoma: A Prospective Intra-Individual Comparison of Six Imaging Tests (CT, MRI, and PET/CT Using 68Ga-DOTATATE, FDG, 18F-FDOPA, and 18F-FDA)

Background: Recent professional society guidelines for radionuclide imaging of sporadic pheochromocytoma (PHEO) recommend 18F-FDOPA as the radiotracer of choice, deeming 68Ga-DOTATATE and FDG to be secondand third-line agents, respectively. An additional agent, 18F-FDA, remains experimental for PHEO detection. A paucity of research has performed head-to-head comparison among these agents. Purpose: To perform an intra-individual comparison of 68Ga-DOTATATE PET/CT, FDG PET/CT, 18F-FDOPA PET/CT, 18F-FDA PET/CT, CT, and MRI in visualization of sporadic primary PHEO. Methods: This prospective study enrolled patients referred with clinical suspicion for sporadic PHEO. Patients were scheduled for 68Ga-DOTATATE PET/CT, FDG PET/CT, 18F-FDOPA PET/CT, 18F-FDA PET/CT, whole-body staging CT (portal venous phase), and MRI, within a 3-month period. PET/CT examinations were reviewed by two nuclear medicine physicians, and CT and MRI were reviewed by two radiologists; differences were resolved by consensus. Readers scored lesions in terms of confidence in diagnosis of PHEO (1-5 scale; 4-5 considered positive for PHEO). Lesion-to-liver SUVmax was computed using both readers' measurements. Interreader agreement was assessed, using intraclass correlation coefficients (ICCs) for SUVmax. Analysis included only patients with histologically- confirmed PHEO on resection. Results: The analysis included 14 patients (8 women, 6 men; mean age, 52.4±16.8 years) with PHEO. Both 68Ga-DOTATATE PET/CT and FDG PET/CT were completed in 14/14 patients, 18F-FDOPA PET/CT in 11/14, 18F-FDA PET/CT in 7/14, CT in 12/14, and MRI in 12/14. Mean conspicuity score for PHEO was 5.0±0.0 for 18F-FDOPA PET/ CT, 4.7±0.5 for MRI, 4.6±0.8 for 18F-FDA PET/CT, 4.4±1.0 for 68Ga-DOTATATE PET/CT, 4.3±1.0 for CT, and 4.1±1.5 for FDG PET/CT. The positivity rate for PHEO was 100.0% (11/11) for 18F-FDOPA PET/CT, 100.0% (12/12) for MRI, 85.7% (6/7) for 18F-FDA PET/CT, 78.6% (11/14) for FDG PET/CT, 78.6% (11/14) for 68Ga-DOTATATE, and 66.7% (8/12) for CT. Lesion-to-liver SUVmax was 10.5 for 18F-FDOPA versus 3.0-4.2 for the other tracers. Interreader agreement across modalities ranged from 85.7-100.0% for lesion positivity and from ICC=0.55-1.00 for SUVmax measurements. Conclusion: Findings from this small intra-individual comparative study support 18F-FDOPA PET/CT as a preferred firstline imaging modality in evaluation of sporadic PHEO. Clinical Impact: This study provides data supporting current guidelines for imaging evaluation of suspected PHEO.

Imaging of Pheochromocytoma and Paraganglioma

Imaging plays a critical role in the management of pheochromocytomas and paragangliomas and often guides treatment. The discovery of susceptibility genes associated with these tumors has led to better understanding of clinical and imaging phenotypes. Functional imaging is of prime importance because of its sensitivity and specificity in subtypes of pheochromocytoma and paraganglioma. Several radiopharmaceuticals have been developed to target specific receptors and metabolic processes seen in pheochromocytomas and paragangliomas, including 131I/123I-metaiodobenzylguanidine, 6-18F-fluoro-l-3,4-dihydroxyphenylalanine, 18F-FDG, and 68Ga-DOTA-somatostatin analogs. Two of these have consequently been adapted for therapy. This educational review focuses on the current imaging approaches used in pheochromocytomas and paragangliomas, which vary among clinical and genotypic presentations.

Pheochromocytomas and paragangliomas

PURPOSE OF REVIEW

Great progress has been made in understanding the genetic and molecular basis of pheochromocytoma and paragangliomas (PPGLs). This review highlights the new standards in the diagnosis and management of pediatric PPGLs.

RECENT FINDINGS

The vast majority of pediatric PPGLs have an associated germline mutation, making genetic studies imperative in the work up of these tumors. Somatostatin receptor-based imaging modalities such as 68Ga-DOTATATE and 64Cu-DOTATATE are shown to have the greatest sensitivity in pediatric PPGLs. Peptide receptor radionuclide therapies (PRRTs) such as 177Lu-DOTATATE are shown to have efficacy for treating PPGLs.

SUMMARY

Genetics play an important role in pediatric PPGLs. Advances in somatostatin receptor-based technology have led to use of 68Ga-DOTATATE and 64Cu-DOTATATE as preferred imaging modalities. While surgery remains the mainstay for management of PPGLs, PRRT is emerging as a treatment option for PPGLs.

Metastatic Pheochromocytomas and Abdominal Paragangliomas

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) are believed to harbor malignant potential; about 10% to 15% of pheochromocytomas and up to 50% of abdominal paragangliomas will exhibit metastatic behavior.

EVIDENCE ACQUISITION

Extensive searches in the PubMed database with various combinations of the key words pheochromocytoma, paraganglioma, metastatic, malignant, diagnosis, pathology, genetic, and treatment were the basis for the present review.

DATA SYNTHESIS

To pinpoint metastatic potential in PPGLs is difficult, but nevertheless crucial for the individual patient to receive tailor-made follow-up and adjuvant treatment following primary surgery. A combination of histological workup and molecular predictive markers can possibly aid the clinicians in this aspect. Most patients with PPGLs have localized disease and may be cured by surgery. Plasma metanephrines are the main biochemical tests. Genetic testing is important, both for counseling and prognostic estimation. Apart from computed tomography and magnetic resonance imaging, molecular imaging using 68Ga-DOTATOC/DOTATATE should be performed. 123I-MIBG scintigraphy may be performed to determine whether 131I-MIBG therapy is a possible option. As first-line treatment in patients with metastatic disease, 177Lu-DOTATATE or 131I-MIBG is recommended, depending on which shows best expression. In patients with very low proliferative activity, watch-and-wait or primary treatment with long-acting somatostatin analogues may be considered. As second-line treatment, or first-line in patients with high proliferative rate, chemotherapy with temozolomide or cyclophosphamide + vincristine + dacarbazine is the therapy of choice. Other therapies, including sunitinib, cabozantinib, everolimus, and PD-1/PDL-1 inhibitors, have shown modest effect.

CONCLUSIONS

Metastatic PPGLs need individualized management and should always be discussed in specialized and interdisciplinary tumor boards. Further studies and newer treatment modalities are urgently needed.

The utility of 68Ga-DOTATATE PET/CT in localizing primary/metastatic pheochromocytoma and paraganglioma in children and adolescents - a single-center experience

OBJECTIVES

Pediatric pheochromocytoma and paraganglioma (PPGL) are rare tumors with limited data on the diagnostic performance of ⁶⁸Ga-DOTA(0)-Tyr(3)-octreotate positron emission tomography-computed tomography (⁶⁸Ga-DOTATATE PET/CT). We have described our experience of ⁶⁸Ga-DOTATATE PET/CT in overall and von Hippel Lindau (VHL)-associated pediatric PPGL and compared its sensitivity with that of ¹³¹I-meta-iodobenzyl-guanidine (¹³¹I-MIBG), ¹⁸F-fluorodeoxyglucose PET/CT (¹⁸F-FDG PET/CT), and contrast-enhanced CT (CECT).

METHODS

Retrospective evaluation of consecutive PPGL patients (age: ≤20 years), who had undergone at least one functional imaging [¹³¹I-MIBG, ¹⁸F-FDG PET/CT, and/or ⁶⁸Ga-DOTATATE PET/CT], was done. Composite of anatomical and all the performed functional imaging scans, image comparator (IC), was considered as the gold standard for sensitivity analysis.

RESULTS

In a cohort of 32 patients (16 males, age at diagnosis: 16.4 ± 2.68 years), lesion-wise sensitivity of ⁶⁸Ga-DOTATATE PET/CT (95%) was higher than that of both ¹⁸F-FDG-PET/CT (80%, p=0.027) and ¹³¹I-MIBG (65%, p=0.0004) for overall lesions, than that of ¹⁸F-FDG-PET/CT (100 vs. 67%, p=0.017) for primary PPG, and than that of ¹³¹I-MIBG (93 vs. 42%, p=0.0001) for metastases. In the VHL (n=14), subgroup, ⁶⁸Ga-DOTATATE PET/CT had higher lesion-wise sensitivity (100%) compared to ¹⁸F-FDG PET/CT (74%, p=0.045) and ¹³¹I-MIBG (64%, p=0.0145).

CONCLUSIONS

In our pediatric PPGL cohort, overall lesion-wise sensitivity of ⁶⁸Ga-DOTATATE PET/CT was higher than that of ¹⁸F-FDG PET/CT and ¹³¹I-MIBG scintigraphy. Hence, we recommend ⁶⁸Ga-DOTATATE PET/CT as the preferred modality in pediatric PPGL. ⁶⁸Ga-DOTATATE PET/CT may evolve as a preferred imaging modality for disease surveillance in VHL.

The utility of 68ga-dotatate pet/ct in localizing primary/metastatic pheochromocytoma and paraganglioma: Asian Indian experience

Purpose:

Pheochromocytoma and paraganglioma (PGL), together called PPGL, are rare tumors with a limited number of studies on the diagnostic performance of ⁶⁸Ga-DOTA (0)-Tyr (3)-octreotate positron emission tomography-computed tomography (⁶⁸Ga-DOTATATE PET/CT) from the Asian-Indian subcontinent.

Materials and Methods:

In this retrospective study, PPGL suspects (n = 87) who had undergone at least contrast-enhanced computed tomography (CECT) and ⁶⁸Ga-DOTATATE PET/CT, were included. Lesion-wise, patient-wise, and region-wise sensitivities of ⁶⁸Ga-DOTATATE PET/CT, ¹⁸F fluorodeoxyglucose positron emission tomography CT (¹⁸F-FDG PET/CT, n = 53), ¹³¹I-metaiodobenzylguanidine (¹³¹I-MIBG, n = 37), and CECT were compared, and diagnostic performance of ⁶⁸Ga-DOTATATE PET/CT in the detection of PPGL was calculated.

Results:

⁶⁸Ga-DOTATATE PET/CT had significantly higher lesion-wise sensitivity than ¹³¹I-MIBG for both primary (94% vs 75%, P = 0.004) and metastatic disease (85% vs 59%, P = 0.001) and higher sensitivity than CECT for metastatic lesions (83% vs 43%, P = 0.0001). The lesion-wise sensitivity of ⁶⁸Ga-DOTATATE PET/CT was similar to ¹⁸F-FDG PET/CT for both primary tumors (94% vs 85%, P = 0.08) and metastatic lesions (82% vs 84%, P = 0.76) in the whole cohort but tended to be inferior in the head to head comparison.

Conclusion:

⁶⁸Ga-DOTATATE PET/CT had higher sensitivity for detection of PPGL than ¹³¹I-MIBG (primary and metastatic) and CECT (metastatic) but similar to ¹⁸F-FDG PET/CT (primary and metastatic).

68Ga-DOTATATE PET/MRI for Neuroendocrine Tumors: A Pictorial Review

Neuroendocrine tumors (NETs) constitute a variety of neoplastic entities and exhibit variable degrees of neuroendocrine differentiation and phenotypes, as well as genetic profiles. Ga-DOTATATE PET is a novel imaging technique for NET. Although PET/CT is commonly utilized for oncologic imaging, PET/MRI is particularly suited for NETs, as MRI provides greater soft tissue contrast than CT, allowing for improved detection and characterization of NETs, particularly when liver metastasis is suspected or needs to be ruled out. The current pictorial review aims to illustrate the complementary advantages, as well as pitfalls of Ga-DOTATATE PET/MRI in the evaluation of NETs.

Plasma metanephrines and prospective prediction of tumor location, size and mutation type in patients with pheochromocytoma and paraganglioma

Objectives

Plasma free metanephrines are commonly used for diagnosis of pheochromocytoma and paraganglioma (PPGLs), but can also provide other information. This multicenter study prospectively examined whether tumor size, location, and mutations could be predicted by these metabolites.

Methods

Predictions of tumor location, size, and mutation type, based on measurements of plasma normetanephrine, metanephrine, and methoxytyramine were made without knowledge of disease in 267 patients subsequently determined to have PPGLs.

Results

Predictions of adrenal vs. extra-adrenal locations according to increased plasma concentrations of metanephrine and methoxytyramine were correct in 93 and 97% of the respective 136 and 33 patients in who these predictions were possible. Predicted mean tumor diameters correlated positively (p<0.0001) with measured diameters; predictions agreed well for pheochromocytomas but were overestimated for paragangliomas. Considering only patients with mutations, 51 of the 54 (94%) patients with NF1 or RET mutations were correctly predicted with those mutations according to increased plasma metanephrine, whereas no or minimal increase in metanephrine correctly predicted all 71 patients with either VHL or SDHx mutations; furthermore, among the latter group increases in methoxytyramine correctly predicted SDHx mutations in 93% of the 29 cases for this specific prediction.

Conclusions

Extents and patterns of increased plasma O-methylated catecholamine metabolites among patients with PPGLs allow predictions of tumor size, adrenal vs. extra-adrenal locations and general types of mutations. Predictions of tumor location are, however, only possible for patients with clearly increased plasma methoxytyramine or metanephrine. Where possible or clinically relevant the predictions are potentially useful for subsequent clinical decision-making.

Genetics, diagnosis, management and future directions of research of phaeochromocytoma and paraganglioma: a position statement and consensus of the Working Group on Endocrine Hypertension of the European Society of Hypertension

: Phaeochromocytoma and paraganglioma (PPGL) are chromaffin cell tumours that require timely diagnosis because of their potentially serious cardiovascular and sometimes life- threatening sequelae. Tremendous progress in biochemical testing, imaging, genetics and pathophysiological understanding of the tumours has far-reaching implications for physicians dealing with hypertension and more importantly affected patients. Because hypertension is a classical clinical clue for PPGL, physicians involved in hypertension care are those who are often the first to consider this diagnosis. However, there have been profound changes in how PPGLs are discovered; this is often now based on incidental findings of adrenal or other masses during imaging and increasingly during surveillance based on rapidly emerging new hereditary causes of PPGL. We therefore address the relevant genetic causes of PPGLs and outline how genetic testing can be incorporated within clinical care. In addition to conventional imaging (computed tomography, MRI), new functional imaging approaches are evaluated. The novel knowledge of genotype-phenotype relationships, linking distinct genetic causes of disease to clinical behaviour and biochemical phenotype, provides the rationale for patient-tailored strategies for diagnosis, follow-up and surveillance. Most appropriate preoperative evaluation and preparation of patients are reviewed, as is minimally invasive surgery. Finally, we discuss risk factors for developing metastatic disease and how they may facilitate personalised follow-up. Experts from the European Society of Hypertension have prepared this position document that summarizes the current knowledge in epidemiology, genetics, diagnosis, treatment and surveillance of PPGL.

Multiple endocrine neoplasia: an update

The multiple endocrine neoplasia (MEN) syndromes include MEN1, MEN2 (formerly MEN2A), MEN3 (formerly MEN2B) and the recently identified MEN4. Clinical presentations are varied and often relate to the overproduction of specific hormones. Understanding the genetics of each syndrome assists in determining screening timelines. Treatments for each manifestation are dependent on location, risk of recurrence or malignancy, hormone excess and surgical morbidity. Multidisciplinary management should include geneticists, genetic counsellors, endocrinologists and endocrine surgeons.

Metastatic pheochromocytoma and paraganglioma: Management of endocrine manifestations, surgery and ablative procedures, and systemic therapies

Metastatic pheochromocytomas and paragangliomas (MPPGs) are rare neuroendocrine tumors. Most patients present with advanced disease that is associated with manifestations of catecholamine release. Surgical resection of the primary tumor and ablative therapies of metastases-whenever possible-may improve clinical outcomes and, perhaps, lengthen the patient's overall survival. Significant steps in understanding the genetic alterations linked to MPPGs and scientific progress made on cancers that share a similar pathogenesis are leading to the recognition of potential systemic therapeutic options. Data derived from clinical trials evaluating targeted therapies such as tyrosine kinase inhibitors, radiopharmaceuticals, immunotherapy, and combinations of these will likely improve the outcomes of patients with advanced and progressive MPPGs. Exemplary of this success is the recent approval in the United States of the high-specific-activity iodine¹³¹ meta-iodine-benzylguanidine (MIBG) for patients with unresectable and progressive MPPGs that express the noradrenaline transporter. This review will discuss the therapeutic approaches for patients with MPPGs.

Diagnostic des phéochromocytomes et paragangliomes

Les phéochromocytomes et les paragangliomes sont des tumeurs rares responsables d’une surmorbidité et d’une surmortalité. Au cours de ces 20 dernières années, de nombreuses avancées ont permis de mieux les caractériser sur le plan phénotypique (via l’imagerie métabolique) et génotypique (avec la mise en évidence de nombreux gènes de prédisposition). La prise en charge d’un phéochromocytome ou d’un paragangliome nécessite désormais le recours à un centre expert dès la phase diagnostique. L’objectif de cette revue est de souligner les principales caractéristiques de ces tumeurs, et ce, afin de sensibiliser le clinicien aux différentes étapes permettant d’aboutir à une prise en charge optimale.

Molecular imaging and radionuclide therapy of pheochromocytoma and paraganglioma in the era of genomic characterization of disease subgroups

In recent years, advancement in genetics has profoundly helped to gain a more comprehensive molecular, pathogenic, and prognostic picture of pheochromocytomas and paragangliomas (PPGLs). Newly discovered molecular targets, particularly those that target cell membranes or signaling pathways have helped move nuclear medicine in the forefront of PPGL precision medicine. This is mainly based on the introduction and increasing experience of various PET radiopharmaceuticals across PPGL genotypes quickly followed by implementation of novel radiotherapies and revised imaging algorithms. Particularly, 68Ga-labeled-SSAs have shown excellent results in the diagnosis and staging of PPGLs and in selecting patients for PRRT as a potential alternative to 123/131I-MIBG theranostics. PRRT using 90Y/177Lu-DOTA-SSAs has shown promise for treatment of PPGLs with improvement of clinical symptoms and/or disease control. However, more well-designed prospective studies are required to confirm these findings, in order to fully exploit PRRT's antitumoral properties to obtain the final FDA approval. Such an approval has recently been obtained for high-specific-activity 131I-MIBG for inoperable/metastatic PPGL. The increasing experience and encouraging preliminary results of these radiotherapeutic approaches in PPGLs now raises an important question of how to further integrate them into PPGL management (e.g. monotherapy or in combination with other systemic therapies), carefully taking into account the PPGLs locations, genotypes, and growth rate. Thus, targeted radionuclide therapy (TRT) should preferably be performed at specialized centers with an experienced interdisciplinary team. Future perspectives include the introduction of dosimetry and biomarkers for therapeutic responses for more individualized treatment plans, α-emitting isotopes, and the combination of TRT with other systemic therapies.

Current Management of Pheochromocytoma/Paraganglioma: A Guide for the Practicing Clinician in the Era of Precision Medicine

Pheochromocytomas and paragangliomas (PCC/PGLs) are rare, mostly catecholamine-producing neuroendocrine tumors of the adrenal gland (PCCs) or the extra-adrenal paraganglia (PGL). They can be separated into three different molecular clusters depending on their underlying gene mutations in any of the at least 20 known susceptibility genes: The pseudohypoxia-associated cluster 1, the kinase signaling-associated cluster 2, and the Wnt signaling-associated cluster 3. In addition to tumor size, location (adrenal vs. extra-adrenal), multiplicity, age of first diagnosis, and presence of metastatic disease (including tumor burden), other decisive factors for best clinical management of PCC/PGL include the underlying germline mutation. The above factors can impact the choice of different biomarkers and imaging modalities for PCC/PGL diagnosis, as well as screening for other neoplasms, staging, follow-up, and therapy options. This review provides a guide for practicing clinicians summarizing current management of PCC/PGL according to tumor size, location, age of first diagnosis, presence of metastases, and especially underlying mutations in the era of precision medicine.

European Association of Nuclear Medicine Practice Guideline/Society of Nuclear Medicine and Molecular Imaging Procedure Standard 2019 for radionuclide imaging of phaeochromocytoma and paraganglioma

PURPOSE

Diverse radionuclide imaging techniques are available for the diagnosis, staging, and follow-up of phaeochromocytoma and paraganglioma (PPGL). Beyond their ability to detect and localise the disease, these imaging approaches variably characterise these tumours at the cellular and molecular levels and can guide therapy. Here we present updated guidelines jointly approved by the EANM and SNMMI for assisting nuclear medicine practitioners in not only the selection and performance of currently available single-photon emission computed tomography and positron emission tomography procedures, but also the interpretation and reporting of the results.

METHODS

Guidelines from related fields and relevant literature have been considered in consultation with leading experts involved in the management of PPGL. The provided information should be applied according to local laws and regulations as well as the availability of various radiopharmaceuticals.

CONCLUSION

Since the European Association of Nuclear Medicine 2012 guidelines, the excellent results obtained with gallium-68 (68Ga)-labelled somatostatin analogues (SSAs) in recent years have simplified the imaging approach for PPGL patients that can also be used for selecting patients for peptide receptor radionuclide therapy as a potential alternative or complement to the traditional theranostic approach with iodine-123 (123I)/iodine-131 (131I)-labelled meta-iodobenzylguanidine. Genomic characterisation of subgroups with differing risk of lesion development and subsequent metastatic spread is refining the use of molecular imaging in the personalised approach to hereditary PPGL patients for detection, staging, and follow-up surveillance.

11C-hydroxy-ephedrine-PET/CT in the Diagnosis of Pheochromocytoma and Paraganglioma

Pheochromocytomas (PCC) and paragangliomas (PGL) may be difficult to diagnose because of vague and uncharacteristic symptoms and equivocal biochemical and radiological findings. This was a retrospective cohort study in 102 patients undergoing ¹¹C-hydroxy-ephedrine (¹¹C-HED)-PET/CT because of symptoms and/or biochemistry suspicious for PCC/PGL and/or with radiologically equivocal adrenal incidentalomas. Correlations utilized CT/MRI, clinical, biochemical, surgical, histopathological and follow-up data. ¹¹C-HED-PET/CT correctly identified 19 patients with PCC and six with PGL, missed one PCC, attained one false positive result (nodular hyperplasia) and correctly excluded PCC/PGL in 75 patients. Sensitivity, specificity, positive and negative predictive values of ¹¹C-HED-PET/CT for PCC/PGL diagnosis was 96%, 99%, 96% and 99%, respectively. In 41 patients who underwent surgical resection and for whom correlation to histopathology was available, the corresponding figures were 96%, 93%, 96% and 93%, respectively. Tumor ¹¹C-HED-uptake measurements (standardized uptake value, tumor-to-normal-adrenal ratio) were unrelated to symptoms of catecholamine excess (p > 0.05) and to systolic blood pressure (p > 0.05). In PCC/PGL patients, norepinephrine and systolic blood pressure increased in parallel (R² = 0.22, p = 0.016). ¹¹C-HED-PET/CT was found to be an accurate tool to diagnose and rule out PCC/PGL in complex clinical scenarios and for the characterization of equivocal adrenal incidentalomas. PET measurements of tumor ¹¹C-HED uptake were not helpful for tumor characterization.

Impact of 123 I-MIBG scintigraphy on clinical decision making in pheochromocytoma and paraganglioma

CONTEXT

Cross sectional imaging with computed tomography (CT) or magnetic resonance imaging (MRI) is regarded as a first-choice modality for tumor localization in patients with pheochromocytoma and paraganglioma (PPGL). 123I-labeled metaiodobenzylguanidine (123I-MIBG) is widely used for functional imaging but the added diagnostic value is controversial.

OBJECTIVE

To establish the virtual impact of adding 123I-MIBG scintigraphy to CT or MRI on diagnosis and treatment of PPGL.

DESIGN

International multicenter retrospective study.

INTERVENTION

None.

PATIENTS

236 unilateral adrenal, 18 bilateral adrenal, 48 unifocal extra-adrenal, 12 multifocal and 26 metastatic PPGL.

MAIN OUTCOME MEASURES

Patients underwent both anatomical imaging (CT and/or MRI) and 123I-MIBG scintigraphy. Local imaging reports were analyzed centrally by two independent observers who were blinded to the diagnosis. Imaging-based diagnoses determined by CT/MRI only, 123I-MIBG only, and CT/MRI combined with 123I-MIBG scintigraphy were compared with the correct diagnoses.

RESULTS

The rates of correct imaging-based diagnoses determined by CT/MRI only versus CT/MRI plus 123I-MIBG scintigraphy were similar: 89.4 versus 88.8%, respectively, (P=0.50). Adding 123I-MIBG scintigraphy to CT/MRI resulted in a correct change in the imaging-based diagnosis and ensuing virtual treatment in four cases (1.2%: two metastatic instead of non-metastatic, one multifocal instead of single, one unilateral instead of bilateral adrenal) at the cost of an incorrect change in seven cases (2.1%: four metastatic instead of non-metastatic, two multifocal instead of unifocal and one bilateral instead of unilateral adrenal).

CONCLUSIONS

For the initial localization of PPGL, the addition of 123I-MIBG scintigraphy to CT/MRI rarely improves the diagnostic accuracy at the cost of incorrect interpretation in others, even when 123I-MIBG scintigraphy is restricted to patients who are at risk for metastatic disease. In this setting, the impact of 123I-MIBG scintigraphy on clinical decision-making appears very limited.