New imaging approaches to phaeochromocytomas and paragangliomas

[Diagnosis and management of patients with pheochromocytoma/paraganglioma: Consensus of experts of the Russian Medical Society for Arterial Hypertension and the Multidisciplinary Group for the Diagnosis and Treatment of Neuroendocrine Tumors]

The understanding of the nature of catecholamine-secreting tumors has changed significantly in recent years, affecting terminology and classification. Phaeochromocytoma/paraganglioma (PCC/PG) is a rare neuroendocrine tumor from chromaffin tissue that produces and secretes catecholamines. The incidence of PCC/PG is relatively low, with 2-8 cases per 1 million population per year; among patients with arterial hypertension, their prevalence is 0.2-0.6%. However, delayed diagnosis of PCC/PG is associated with a high risk of cardiovascular complications and a high mortality rate. The consensus presents the clinical manifestations of the disease with an emphasis on the course of arterial hypertension as the most common symptom in PCC/PG; modern ideas about the features of diagnosis, aspects of preoperative preparation, treatment, and follow-up of patients with PCC/PG are considered.

Intraoperative Scintigraphy With Portable Gamma Camera for the Localization of Interaortocaval Paraganglioma

ABSTRACT

A 15-year-old adolescent girl diagnosed of interaortocaval paraganglioma with a positive 123I-MIGB SPECT/CT and 1 unsuccessful prior surgery was operated on with the assistance of a handheld gamma camera. Once the lesion was located and removed, 2 images were taken, one of the surgical field (without 123I-MIGB uptake) and another of the tumor ex vivo (with high 123I-MIGB uptake), confirming that the lesion had been satisfactorily excised. This case highlights the use of a portable gamma camera as a useful tool to locate this rare tumor, with a SPECT/CT positive for 123I-MIGB and a difficult anatomical location suspected.

Multidisciplinary practice guidelines for the diagnosis, genetic counseling and treatment of pheochromocytomas and paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors that arise from chromaffin cells of the adrenal medulla and the sympathetic/parasympathetic neural ganglia, respectively. The heterogeneity in its etiology makes PPGL diagnosis and treatment very complex. The aim of this article was to provide practical clinical guidelines for the diagnosis and treatment of PPGLs from a multidisciplinary perspective, with the involvement of the Spanish Societies of Endocrinology and Nutrition (SEEN), Medical Oncology (SEOM), Medical Radiology (SERAM), Nuclear Medicine and Molecular Imaging (SEMNIM), Otorhinolaryngology (SEORL), Pathology (SEAP), Radiation Oncology (SEOR), Surgery (AEC) and the Spanish National Cancer Research Center (CNIO). We will review the following topics: epidemiology; anatomy, pathology and molecular pathways; clinical presentation; hereditary predisposition syndromes and genetic counseling and testing; diagnostic procedures, including biochemical testing and imaging studies; treatment including catecholamine blockade, surgery, radiotherapy and radiometabolic therapy, systemic therapy, local ablative therapy and supportive care. Finally, we will provide follow-up recommendations.

Somatostatin Receptors and Analogs in Pheochromocytoma and Paraganglioma: Old Players in a New Precision Medicine World

Neuroendocrine tumors overexpress somatostatin receptors, which serve as important and unique therapeutic targets for well-differentiated advanced disease. This overexpression is a well-established finding in gastroenteropancreatic neuroendocrine tumors which has guided new medical therapies in the administration of somatostatin analogs, both "cold", particularly octreotide and lanreotide, and "hot" analogs, chelated to radiolabeled isotopes. The binding of these analogs to somatostatin receptors effectively suppresses excess hormone secretion and tumor cell proliferation, leading to stabilization, and in some cases, tumor shrinkage. Radioisotope-labeled somatostatin analogs are utilized for both tumor localization and peptide radionuclide therapy, with ⁶⁸Ga-DOTATATE and ¹⁷⁷Lu-DOTATATE respectively. Benign and malignant pheochromocytomas and paragangliomas also overexpress somatostatin receptors, irrespective of embryological origin. The pattern of somatostatin receptor overexpression is more prominent in succinate dehydrogenase subunit B gene mutation, which is more aggressive than other subgroups of this disease. While the Food and Drug Administration has approved the use of ⁶⁸Ga-DOTATATE as a radiopharmaceutical for somatostatin receptor imaging, the use of its radiotherapeutic counterpart still needs approval beyond gastroenteropancreatic neuroendocrine tumors. Thus, patients with pheochromocytoma and paraganglioma, especially those with inoperable or metastatic diseases, depend on the clinical trials of somatostatin analogs. The review summarizes the advances in the utilization of somatostatin receptor for diagnostic and therapeutic approaches in the neuroendocrine tumor subset of pheochromocytoma and paraganglioma; we hope to provide a positive perspective in using these receptors as targets for treatment in this rare condition.

Research progress of 18F labeled small molecule positron emission tomography (PET) imaging agents

With the development of positron emission tomography (PET) technology, a variety of PET imaging agents labeled with radionuclide ¹⁸F have been developed and widely used in the diagnosis and treatment of various clinical diseases in recent years. For example, they have showed a great value of study in the field of tumor detection, tumor treatment and evaluation of tumor therapy in a non-invasive, qualitative and quantitative way. In this review, we highlight the recent development in chemical synthesis, structure and characterization, imaging characterization, and potential applications of these ¹⁸F labeled small molecule PET imaging agents for the past five years. The development and application of ¹⁸F labeled small molecules will expand our knowledge of the function and distribution of diseases-related molecular targets and shed light on the diagnosis and treatment of various diseases including tumors.

MEN2-related pheochromocytoma: current state of knowledge, specific characteristics in MEN2B, and perspectives

Multiple endocrine neoplasia type 2 (MEN2) is a rare hereditary syndrome due to mutations of the proto-oncogene REarranged during Transfection (RET), defined by the association of medullary thyroid carcinoma (MTC) in almost 100% cases, and pheochromocytoma in roughly 50% (primary hyperparathyroidism can be seen in 10-20% of patients with MEN2A). Early thyroidectomy and the efficacy of novel tyrosine kinase inhibitors modified the natural history of MTC, with possibilities of cure or long-term control. The second main compound, pheochromocytoma, is reported with a variable penetrance, from 10 to 80% cases, depending on the mutation of RET. Pheochromocytoma constitutes the main disease to screen in patients with RET mutations. Pheochromocytoma clinical and biochemical diagnosis, as well as the way to treat it are thus crucial. This review will thus focus on the epidemiological specificities of MEN2-related pheochromocytoma, the genotype/phenotype relationship, the modern imaging modalities necessary to confirm the diagnosis in this hereditary context, as well as the optimal management and the possibilities of adrenal sparing surgery. Additional information will include the natural history of MEN2B-pheochromocytoma, the rare cases of malignant pheochromocytoma, and the factors that could modify the penetrance between individuals carrying the same mutation, especially in the same family.

68Ga-DOTATATE PET/CT Compared with 131I-MIBG SPECT/CT in the Evaluation of Neural Crest Tumors

Objective(s):

⁶⁸Ga-DOTATATE positron emission tomography (PET)/computed tomography (CT) has shown promising results in imaging of neural crest tumors (NCT). Herein, we compared the performance of ⁶⁸Ga-DOTATATE PET/CT and ¹³¹I-MIBG single photon emission computed tomography (SPECT)/CT in the initial diagnosis, staging and follow-up of patients with NCTs.

Methods:

Twenty-five patients (males:females=8:17; age range=2–71 years) with clinically proven or suspicious neuroblastoma, pheochromocytoma (PCC) or paraganglioma (PGL) were enrolled in this prospective study and underwent both ⁶⁸Ga-DOTATATE PET/CT and ¹³¹I-MIBG SPECT/CT. A composite reference standard derived from histopathological information, together with anatomical and functional imaging findings, was used to validate the results. Imaging findings were assessed on a per-patient and on a per-lesion basis. Sensitivity and accuracy were assessed using McNemar’s test.

Results:

Referring to radiological imaging and histopathological findings as reference standard, ⁶⁸Ga-DOTATATE and ¹³¹I-MIBG scans showed a sensitivity and accuracy of (100%, 96%) and (86.7%, 88%), respectively, on a per-patient basis. In PCC/PGL patients, on a per-patient basis, the sensitivity of ⁶⁸Ga-DOTATATE was 100% and that of ¹³¹I-MIBG was 77.8%. In neuroblastoma patients, on a per-patient basis, the sensitivities of both ⁶⁸Ga-DOTATATE and ¹³¹I-MIBG were 100%. Overall, in this patient cohort, ⁶⁸Ga-DOTATATE PET/CT identified 52 lesions and ¹³¹I-MIBG SPECT/CT identified only 30 lesions. On a per-lesion analysis, ⁶⁸Ga-DOTATATE was found to be superior to ¹³¹I-MIBG in detecting lesions in all anatomical locations, particularly osseous lesions. According to the McNemar test results, differences were not statistically significant.

Conclusion:

This relatively small patient cohort suggests ⁶⁸Ga-DOTATATE PET/CT be superior to ¹³¹I-MIBG SPECT/CT in providing particularly valuable information for both primary staging and follow-up in patients with NCT.

Pheochromocytoma

Pheochromocytomas are rare tumors originating in the adrenal medulla. They may be sporadic or in the context of a hereditary syndrome. A considerable number of pheochromocytomas carry germline or somatic gene mutations, which are inherited in the autosomal dominant way. All patients should undergo genetic testing. Symptoms are due to catecholamines over production or to a mass effect. Diagnosis is confirmed by raised plasma or urine metanephrines or normetanephrines. Radiology assists in the tumor location and any local invasion or metastasis. All the patients should have preoperative preparation with α-blockers and/or other medications to control hypertension, arrhythmia, and volume expansion. Surgery is the definitive treatment. Follow up should be life-long.

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.

Aggressive Imaging Features in a Malignant Pheochromocytoma With a Novel Mutation of the SDHB Gene

We describe a 15-year-old boy with a huge bilateral adrenal pheochromocytoma that had a de novo germline mutation in the succinate dehydrogenase subunit B (SDHB) gene. F-FDG PET/CT revealed bilateral metabolically active large masses in the adrenal glands and the activated brown adipose tissues. The I-MIBG scintigraphic findings revealed only a mild accumulation of MIBG in the right adrenal mass, but a high uptake in the left adrenal mass. Thus, F-FDG PET/CT imaging may be more effective than I-MIBG scintigraphy for the evaluation of pheochromocytomas that are associated with highly malignant characteristics resulting from mutations of the SDHB gene.

Looking beyond the thyroid: advances in the understanding of pheochromocytoma and hyperparathyroidism phenotypes in MEN2 and of non-MEN2 familial forms

Over the last years, the knowledge of MEN2 and non-MEN2 familial forms of pheochromocytoma (PHEO) has increased. In MEN2, PHEO is the second most frequent disease: the penetrance and age at diagnosis depend on the mutation of RET Given the prevalence of bilateral PHEO (50% by age 50), adrenal sparing surgery, aimed at sparing a part of the adrenal cortex to avoid adrenal insufficiency, should be systematically considered in patients with bilateral PHEO. Non-MEN2 familial forms of PHEO now include more than 20 genes: however, only small phenotypic series have been reported, suggesting that phenotypic features of isolated hereditary PHEO must be better explored, and follow-up series are needed to better understand the outcome of patients carrying mutations of these genes. The first part of this review will mainly focus on these points. In the second part, a focus will be given on MEN2 and non-MEN2 familial forms of hyperparathyroidism (HPTH). Again, the management of MEN2 HPTH should be aimed at curing the disease while preserving an optimal quality of life by a tailored parathyroidectomy. The phenotypes and outcome of MEN1-, MEN4- and HRPT2-related HPTH are briefly described, with a focus on the most recent literature data and is compared with familial hypocalciuric hypercalcemia.

Failure of MIBG scan to detect metastases in SDHB-mutated pediatric metastatic pheochromocytoma

¹²³ I-meta-iodo benzyl guanidine (MIBG) scans are considered the gold standard imaging in neuroblastoma; however, flouro deoxy glucose positron emission tomography (FDG-PET) scans have increased sensitivity in adults with pheochromocytoma/paraganglioma. We describe a pediatric patient initially considered to have localized neuroblastoma based on anatomical imaging and ¹²³ I-MIBG scan, but subsequent investigations revealed germline succinate dehydrogenase complex iron sulfur subunit B (SDHB) mutation-associated pheochromocytoma with multiple FDG-avid skeletal metastases. We then compared ¹²³ I-MIBG and FDG-PET scans in children with metastatic pheochromocytoma/paraganglioma. FDG-PET was superior to ¹²³ I-MIBG scan for the detection of skeletal metastases (median number of skeletal lesions detected 10 [range 1-30] vs. 2 [range 1-26], respectively; P = 0.005 by t-test). FDG-PET should be considered the functional scan of choice in children with pheochromocytoma/paraganglioma.

Quantitative 18F-DOPA PET/CT in pheochromocytoma: the relationship between tumor secretion and its biochemical phenotype

INTRODUCTION

¹⁸F-FDOPA illustrates the properties of uptake and storage of catecholamines in pheochromocytomas (PHEOs). Until now, the relationship between ¹⁸F-FDOPA quantitative parameters and a PHEO secretory profile has not been specifically evaluated.

MATERIALS AND METHODS

Fifty-six patients (56% females, median age: 47.5 yrs) with non-metastatic PHEO, evaluated by ¹⁸F-FDOPA PET/CT, were included in this retrospective study. Forty-five patients had negative genetic testing (80.4%); five patients (8.9%) had RET, two patients (3.6%) had SDHB, two had SDHD (3.6%), one patient (1.8%) had NF1, and one patient had a VHL (1.8%) mutation. Correlation between ¹⁸F-FDOPA metabolic parameters (tumor SUVmax, tumor SUVmean, tumor SUVmax/liver SUVmax, MTV 42%, total lesion uptake), urinary metanephrines (MNs), and plasma chromogranin A (CgA) were evaluated.

RESULTS

All patients had positive ¹⁸F-FDOPA PET/CT. On univariate analysis, there was a strong correlation between all metabolic parameters and urinary MNs and plasma chromogranin A (CgA). The highest correlations were observed between total lesion (TL) uptake and the value of urinary MNs regardless of their nature (p = 8.10^-15 and r = 0.80) and between MTV 42% and plasma CgA levels (p = 2.10^-9, r = 0.74). On multivariate analysis, the correlation of uptake parameters and CgA levels did not persist further due to the relation of CgA and tumor diameter. A correlation between TL uptake and the normetanephrine/metanephrine ratio (NMN/MN) was also found, a finding that was in accordance with in vitro studies, which were found to have a higher catecholamine content in epinephrine producing PHEOs.

CONCLUSION

This retrospective study shows a correlation between ¹⁸F-FDOPA uptake, especially using TL uptake, urinary MNs, and a PHEO biochemical phenotype. This illustrates that beyond its localization value, ¹⁸F-FDOPA PET further enables PHEO characterization at a specific metabolic level.

Pheochromocytoma, diagnosis and treatment: Review of the literature

Objective. We conducted an extensive review of the literature and tried to cite the most recent recommendations concerning the pheochromocytoma (PHEO).

Methods. Pub Med and Google Scholar databases were searched systematically for studies concerning pheochromocytomas (intra-adrenal paragangliomas) from 1980 until 2016. Bibliographies were searched to find additional articles.

Results. More than four times elevation of plasma fractionated metanephrines or elevated 24-h urinary fractionated metanephrines are keys to diagnosing pheochromocytoma. If the results are equivocal then we perform the clonidine test. If we have not done it already, we preferably do a CT scan and/or an MRI scan. The patient needs pre-treatment with α1-blockers at least 10–14 days before operation. Alternatives or sometimes adjuncts are Calcium Channels Blockers and/or β-Blockers. Several familial syndromes are associated with PHEO and genetic testing should be considered.

Conclusions. The biggest problem for pheochromocytoma is to suspect it in the first place. Elevated metanephrines establish the diagnosis. With the proper preoperative preparation the risks during operation and the postoperative period are minimal. If there is a risk of the hereditable mutation, it is strongly suggested that all the patients with pheochromocytoma need clinical genetic testing.

Diagnostic Imaging of Pregnant Women - The Role of Magnetic Resonance Imaging

BACKGROUND

Presentation of magnetic resonance imaging (MRI) findings in pregnant women in the Department of Diagnostic Imaging, Institute of Mother and Child, Warsaw, Poland.

MATERIAL/METHODS

Forty-three symptomatic pregnant women underwent MRI between 9 and 33 weeks of gestation (mean of 23 weeks). Moreover, we included 2 pregnant women who underwent fetal MRI and had incidental abnormalities.

RESULTS

In 9 cases, we excluded the suspected brain abnormalities. In 4 cases, we found unremarkable changes in the brain without clinical significance. One patient was diagnosed with multiple sclerosis, one with cortical dysplasia, one with pineal hemorrhage and one with a brain tumor. On abdominal MRI, 2 patients had normal findings, one patient had colon cancer with a hepatic metastasis, one patient had a hepatic angioma, one patient had an extraadrenal pheochromocytoma, one patient had an abscess in the iliopsoas muscle, 9 patients had myomas, two patients had ovarian simple cysts, two endometrial cysts, three dermoid cysts, one patient had sacrococcygeal teratoma, one patient had a cystadenofibroma (partial borderline tumor), one patient had an androgenic ovarian tumor and two patients had hyperreactio luteinalis. One patient was diagnosed with transient osteoporosis of the hip and one with a stress fracture of the sacral bone.

CONCLUSIONS

Magnetic resonance imaging is the best imaging modality for pregnant women. Although ultrasonography is the method of choice, doubtful cases as well as structures that cannot be examined with ultrasonography can be non-invasively evaluated with MRI.

Morphological and functional imaging of neck paragangliomas

OBJECTIVE

To review the optimal techniques for localization and characterization of neck paragangliomas (PGL).

MATERIAL AND METHODS

Systematic review of the literature from the PubMed/Medline database.

RESULTS

Neck PGL are hypervascular tumours essentially arising from paraganglionic tissue situated at the carotid bifurcation (carotid body) and along the vagus nerve. Morphological and functional imaging are indicated to confirm the diagnosis, identify multifocal disease and for local and regional staging. MR angiography is the noninvasive technique of choice. CT scan and especially CT angiography are excellent alternatives for diagnosis and staging. Conventional arteriography remains useful preoperatively for embolization and occlusion tests. Functional imaging allows localization and characterization of PGLs. Somatostatin receptor scintigraphy (SRS) was the reference imaging technique for staging of sporadic PGLs. The indications for PET imaging have been extended over recent years in parallel with the development of new tracers such as [¹⁸F]-FDOPA PET or ⁶⁸Gallium-labelled DOTA peptides. ⁶⁸Gallium-labelled DOTA peptides has become the first-line imaging modality in the evaluation of cervical PGLs, regardless of the genetic background.

CONCLUSION

Morphological and functional imaging is essential for the staging of neck PGL.

PET/CT comparing (68)Ga-DOTATATE and other radiopharmaceuticals and in comparison with CT/MRI for the localization of sporadic metastatic pheochromocytoma and paraganglioma

PURPOSE

Pheochromocytomas/paragangliomas (PPGLs) and their metastases are tumors that predominantly express somatostatin receptor 2 (SSR2). (68)Ga-DOTA(0)-Tyr(3)-octreotate ((68)Ga-DOTATATE) is a PET radiopharmaceutical with both high and selective affinity for SSRs. The purpose of this study was to evaluate the utility of (68)Ga-DOTATATE in comparison with other specific and nonspecific radiopharmaceuticals recommended in the current guidelines for the localization of metastatic sporadic PPGL by PET/CT.

METHODS

This prospective study included 22 patients (15 men, 7 women; aged 50.0 ± 13.9 years) with confirmed metastatic PPGL, a negative family history for PPGL, and negative genetic testing, who underwent (68)Ga-DOTATATE, (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) PET/CT, and CT/MRI. Only 12 patients underwent an additional (18)F-fluorodihydroxyphenylalanine ((18)F-FDOPA) PET/CT scan and only 11 patients underwent an additional (18)F-fluorodopamine ((18)F-FDA) PET/CT scan. The rates of detection of metastatic lesions were compared among all the imaging studies. A composite of all functional and anatomical imaging studies served as the imaging comparator.

RESULTS

(68)Ga-DOTATATE PET/CT showed a lesion-based detection rate of 97.6 % (95 % confidence interval, CI, 95.8 - 98.7 %). (18)F-FDG PET/CT, (18)F-FDOPA PET/CT, (18)F-FDA PET/CT, and CT/MRI showed detection rates of 49.2 % (CI 44.5 - 53.6 %; p < 0.01), 74.8 % (CI 69.0 - 79.9 %); p < 0.01), 77.7 % (CI 71.5 - 82.8 %; p < 0.01), and 81.6 % (CI 77.8 - 84.8 %; p < 0.01), respectively.

CONCLUSION

The results of this study demonstrate the superiority of (68)Ga-DOTATATE PET/CT in the localization of sporadic metastatic PPGLs compared to all other functional and anatomical imaging modalities, and suggest modification of future guidelines towards this new imaging modality.

Molecular imaging in hereditary succinate dehydrogenase mutation-related paragangliomas

Multiple paraganglioma (PGL) syndromes related to succinate dehydrogenase (SDH) gene mutations are rare hereditary conditions. These present with heterogeneous clinical signs and symptoms and in many cases are difficult to classify. We summarize the pathophysiological, clinical, laboratory, and morphological and functional imaging characteristics of SDH gene mutation PGLs, emphasizing F-FDG and F-DOPA PET/CT. We correlate clinical and genetic features of SDH-related PGLs with specific PET radiopharmaceuticals, with the aim to obtain an "individualized" diagnostic approach.

68Ga-DOTATATE PET/CT in the Localization of Head and Neck Paragangliomas Compared with Other Functional Imaging Modalities and CT/MRI

Pheochromocytomas/paragangliomas overexpress somatostatin receptors, and recent studies have already shown excellent results in the localization of sympathetic succinate dehydrogenase complex, subunit B, mutation-related metastatic pheochromocytomas/paragangliomas using (68)Ga-DOTATATE PET/CT. Therefore, the goal of our study was to assess the clinical utility of this functional imaging modality in parasympathetic head and neck paragangliomas (HNPGLs) compared with anatomic imaging with CT/MRI and other functional imaging modalities, including (18)F-fluorohydroyphenylalanine ((18)F-FDOPA) PET/CT, currently the gold standard in the functional imaging of HNPGLs.

METHODS

(68)Ga-DOTATATE PET/CT was prospectively performed in 20 patients with HNPGLs. All patients also underwent (18)F-FDOPA PET/CT, (18)F-FDG PET/CT, and CT/MRI, with 18 patients also undergoing (18)F-fluorodopamine ((18)F-FDA) PET/CT. (18)F-FDOPA PET/CT and CT/MRI served as the imaging comparators.

RESULTS

Thirty-eight lesions in 20 patients were detected, with (18)F-FDOPA PET/CT identifying 37 of 38 and CT/MRI identifying 23 of 38 lesions (P < 0.01). All 38 and an additional 7 lesions (P = 0.016) were detected on (68)Ga-DOTATATE PET/CT. Significantly fewer lesions were identified by (18)F-FDG PET/CT (24/38, P < 0.01) and (18)F-FDA PET/CT (10/34, P < 0.01).

CONCLUSION

(68)Ga-DOTATATE PET/CT identified more lesions than other imaging modalities. With the results of the present study, and the increasing availability and use of DOTA analogs in the therapy of neuroendocrine tumors, we expect that (68)Ga-DOTATATE PET/CT will become the preferred functional imaging modality for HNPGLs in the near future.

The incremental benefit of functional imaging in pheochromocytoma/paraganglioma: a systematic review

Computed tomography (CT) and magnetic resonance imaging (MRI) are the major imaging modalities used for the localization of catecholamine-producing tumors (pheochromocytoma and paraganglioma). Functional imaging (FI) offers an alternative approach to localize, evaluate, and stage these tumors. Our objective was to describe the additive benefit of FI studies for patients with pheochromocytoma and paraganglioma (PPG) who have undergone MRI or CT scan evaluation. We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus from database inception through June 2012 for studies that included patients with biochemically proven PPGs who underwent CT or MRI and additional FI for the localization of PPGs. We included 32 studies enrolling a total of 1,264 patients with a mean age of 43-years old. The studies were uncontrolled and evaluated six FI modalities. FI tests provided small additive value to CT/MRI, aiding in the localization of only 24/1,445 primary cases (1.4 %) and 28/805 metastatic cases (3.5 %). In metastatic cases, 6-[F-18]fluoro-L-dihydroxyphenylalanine (DOPA) and fluorodopamine-PET (FDA) were the FI tests most successful at identifying disease missed by CT/MRI, providing additional benefit in 6/60 (10 %) and 5/78 (6.4 %) cases, respectively. No clinically significant findings were observed in any of the predefined subgroups. No study evaluated the impact of FI on the completeness of surgical resection or other patient-important outcomes. Observational evidence suggests that FI tests have a limited additional role in patients with PPGs who have undergone CT/MRI evaluation. However, the role of FI tests in specific subgroups of patients with atypical presentations (metastatic, extra-adrenal) as well as the use of hybrid FI tests should be explored. Further research should also evaluate the impact of FI tests on patient-important outcomes.

A Rare Case of Adrenal Pheochromocytoma with Unusual Clinical and Biochemical Presentation: A Case Report and Literature Review

A 50-year-old Omani woman presented to the Outpatient Clinic, Royal Hospital, Oman with right upper abdominal pain and backache that had lasted 10 days. She had no palpitation, sweating, or hypertension (blood pressure 122/78mmHg). The patient's history revealed that she had a similar incidence of abdominal pain two months prior, which was a "dull ache" in nature and somewhat associated with headache. The pain was relieved using a mild analgesic drug. Abdominal ultrasonography showed a right adrenal mass, and both computed tomography and magnetic resonance imaging of the adrenal glands confirmed a right adrenal mass consistent with adrenal pheochromocytoma. However, clinical biochemistry tests revealed normal levels of plasma catecholamines (dopamine, norepinephrine, and epinephrine) and metanephrine, which are unusual findings in adrenal pheochromocytoma. Meanwhile, the patient had markedly raised plasma normetanephrine (10-fold) which, together with the normal metanephrine, constitutes a metabolic profile that is compatible with extra-adrenal pheochromocytoma. The patient also had markedly raised chromogranin A (16-fold), consistent with the presence of a neuroendocrine tumor. Laparoscopic right adrenalectomy was done and the adrenal tumor was excised and retrieved in total. Histopathology and immunohistochemistry confirmed the diagnosis of adrenal pheochromocytoma; the tumor cells being positive for chromogranin, synaptophysin, and S-100 protein. Following surgery, the patient did well and showed full recovery at follow-up after three months. Molecular genetic testing showed no pathogenic mutation in pheochromocytoma genes: MAX, SDHA, SDHAF2, SDHB, SDHC, SDHD, VHL, and PRKAR1A. A review of the literature was conducted to identify the pathophysiology and any previous reports of such case. To our knowledge, this is the first report in Oman of the extremely rare entity of pheochromocytoma with an unusual clinical and biochemical scenario.

Superiority of [68Ga]-DOTATATE PET/CT to Other Functional Imaging Modalities in the Localization of SDHB-Associated Metastatic Pheochromocytoma and Paraganglioma

PURPOSE

Patients with succinate dehydrogenase subunit B(SDHB) mutation-related pheochromocytoma/paraganglioma (PHEO/PGL) are at a higher risk for metastatic disease than other hereditary PHEOs/PGLs. Current therapeutic approaches are limited, but the best outcomes are based on the early and proper detection of as many lesions as possible. Because PHEOs/PGLs overexpress somatostatin receptor 2 (SSTR2), the goal of our study was to assess the clinical utility of [(68)Ga]-DOTA(0)-Tyr(3)-octreotate ([(68)Ga]-DOTATATE) positron emission tomography/computed tomography (PET/CT) and to evaluate its diagnostic utility in comparison with the currently recommended functional imaging modalities [(18)F]-fluorodopamine ([(18)F]-FDA), [(18)F]-fluorodihydroxyphenylalanine ([(18)F]-FDOPA), [(18)F]-fluoro-2-deoxy-d-glucose ([(18)F]- FDG) PET/CT as well as CT/MRI.

EXPERIMENTAL DESIGN

[(68)Ga]-DOTATATE PET/CT was prospectively performed in 17 patients with SDHB-related metastatic PHEOs/PGLs. All patients also underwent [(18)F]-FDG PET/CT and CT/MRI, with 16 of the 17 patients also receiving [(18)F]-FDOPA and [(18)F]-FDA PET/CT scans. Detection rates of metastatic lesions were compared between all these functional imaging studies. A composite synthesis of all used functional and anatomical imaging studies served as the imaging comparator.

RESULTS

[(68)Ga]-DOTATATE PET/CT demonstrated a lesion-based detection rate of 98.6% [95% confidence interval (CI), 96.5%-99.5%], [(18)F]-FDG, [(18)F]-FDOPA, [(18)F]-FDA PET/CT, and CT/MRI showed detection rates of 85.8% (CI, 81.3%-89.4%; P < 0.01), 61.4% (CI, 55.6%-66.9%; P < 0.01), 51.9% (CI, 46.1%-57.7%; P < 0.01), and 84.8% (CI, 80.0%-88.5%; P < 0.01), respectively.

CONCLUSIONS

[(68)Ga]-DOTATATE PET/CT showed a significantly superior detection rate to all other functional and anatomical imaging modalities and may represent the preferred future imaging modality in the evaluation of SDHB-related metastatic PHEO/PGL.

Diagnostic Performance of (68)Ga-DOTATATE PET/CT, (18)F-FDG PET/CT and (131)I-MIBG Scintigraphy in Mapping Metastatic Pheochromocytoma and Paraganglioma

PURPOSE

To evaluate the diagnostic performance of (68)Ga-DOTATATE (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)/computed tomography (CT), (18)F-FDG PET/CT and (131)I-MIBG scintigraphy in the mapping of metastatic pheochromocytoma and paraganglioma.

MATERIALS AND METHODS

Seventeen patients (male = 8, female = 9; age range, 13-68 years) with clinically proven or suspicious metastatic pheochromocytoma or paraganglioma were included in this prospective study. Twelve patients underwent all three modalities, whereas five patients underwent (68)Ga-DOTATATE and (131)I-MIBG without (18)F-FDG. A composite reference standard derived from anatomical and functional imaging findings, along with histopathological information, was used to validate the findings. Results were analysed on a per-patient and on per-lesion basis. Sensitivity and accuracy were assessed using McNemar's test.

RESULTS

On a per-patient basis, 14/17 patients were detected in (68)Ga-DOTATATE, 7/17 patients in (131)I-MIBG, and 10/12 patients in (18)F-FDG. The sensitivity and accuracy of (68)Ga-DOTATATE, (131)I-MIBG and (18)F-FDG were (93.3 %, 94.1 %), (46.7 %, 52.9 %) and (90.9 %, 91.7 %) respectively. On a per-lesion basis, an overall of 472 positive lesions were detected; of which 432/472 were identified by (68)Ga-DOTATATE, 74/472 by (131)I-MIBG, and 154/300 (patient, n = 12) by (18)F-FDG. The sensitivity and accuracy of (68)Ga-DOTATATE, (131)I-MIBG and (18)F-FDG were (91.5 %, 92.6 % p < 0.0001), (15.7 %, 26.0 % p < 0.0001) and (51.3 %, 57.8 % p < 0.0001) respectively. Discordant lesions were demonstrated on (68)Ga-DOTATATE, (131)I-MIBG and (18)F-FDG.

CONCLUSIONS

Ga-DOTATATE PET/CT shows high diagnostic accuracy than (131)I-MIBG scintigraphy and (18)F-FDG PET/ CT in mapping metastatic pheochromocytoma and paraganglioma.

Comparison of 131I-MIBG, 68Ga-DOTANOC PET/CT and 18F-FDG PET/CT scans in a patient with extra adrenal paraganglioma associated with SDH-B gene mutation

Paragangliomas (PGLs) due to succinate dehydrogenase subunit B (SDH-B) mutation can be aggressive. A 40-year-old woman with normetanephrine-secreting, extra-adrenal, abdominal PGL due to SDH-B genetic mutation underwent surgical excision of primary, followed by whole-body I-MIBG scan after 6 months, which showed no abnormality. However, Ga-DOTANOC and F-FDG PET/CT scans showed primary site recurrence, hepatic and skeletal metastasis, with latter scan revealing more lesions. We suggest that F-FDG PET should be done in all patients with PGL due to SDH-B mutations, as it may show additional unsuspected lesions that may be missed by other tracers.

Association of urinary bladder paragangliomas with germline mutations in the SDHB and VHL genes

OBJECTIVE

Our primary goal was to examine the clinical characteristics of a series of patients with urinary bladder paragangliomas (UBPGLs), focusing particularly on their genetic backgrounds.

MATERIALS AND METHODS

We analyzed the medical records of patients who presented to the National Institutes of Health with UBPGL from 2000 to 2013 to determine their clinical characteristics and outcomes, biochemical phenotype, tumor size, and genetic background.

RESULTS

Of the 27 patients with UBPGLs who were identified, 17 (63%) had underlying genetic mutations. Overall, 14 (51.9%) patients had a germline mutation in the succinate dehydrogenase subunit B gene (SDHB), and 3 (11.1%) had mutations in the von Hippel-Lindau gene (VHL). Of the 21 patients who had biochemical data available before their first operation, 19 (90.5%) presented with a noradrenergic biochemical phenotype; 7 (33.3%) patients had tumors that also secreted dopamine. In addition, 1 patient (4.8%) had elevated metanephrine levels, and 2 (9.5%) had normal biochemical data. In total, 13 (48.1%) patients in the series were diagnosed with metastatic disease, at either first presentation or follow-up; 6 of these patients (46.1%) had SDHB mutations.

CONCLUSIONS

UBPGLs typically present with a noradrenergic phenotype and are frequently associated with underlying germline mutations. Patients presenting with these rare neuroendocrine tumors should be screened for these mutations. In addition, patients with UBPGLs should be followed up closely for metastatic development regardless of genetic background, as almost half of the patients in this series presented with metastatic disease and less than half of them had SDHB mutations.

Endocrine scintigraphy with hybrid SPECT/CT

Nuclear medicine imaging of endocrine disorders takes advantage of unique cellular properties of endocrine organs and tissues that can be depicted by targeted radiopharmaceuticals. Detailed functional maps of biodistributions of radiopharmaceutical uptake can be displayed in three-dimensional tomographic formats, using single photon emission computed tomography (CT) that can now be directly combined with simultaneously acquired cross-sectional anatomic maps derived from CT. The integration of function depicted by scintigraphy and anatomy with CT has synergistically improved the efficacy of nuclear medicine imaging across a broad spectrum of clinical applications, which include some of the oldest imaging studies of endocrine dysfunction.

Primary paraganglioma located between the thyroid gland and the left common carotid artery: A case report

Head and neck paraganglioma is a rare and predominantly asymptomatic tumor. In the present study, an extremely rare case of asymptomatic paraganglioma located between the left common carotid artery and the left thyroid is described. The clinical presentation, cytomorphology and the immunohistochemical characteristics for the diagnosis of head and neck paraganglioma are described. To the best of our knowledge, only two cases of paraganglioma located between the left common carotid artery and the left thyroid have previously been reported.

18F-DOPA PET/CT in the evaluation of hereditary SDH-deficiency paraganglioma-pheochromocytoma syndromes

PURPOSE

This study aims to evaluate the role of F-DOPA PET/CT in staging and follow-up of paraganglioma syndromes succinate dehydrogenase (SDH)-mutation-related patients, comparing F-DOPA PET/CT results with morphological imaging and biochemical results.

PATIENTS AND METHODS

We retrospectively studied 10 consecutive patients (3 F, 7 M, mean age 32 yrs), all with a genetically demonstrated SDH mutation (5 SDH-D, 4 SDH-B, and 1 SDH-C) and all addressed to F-DOPA PET/CT scan. Seven patients had already been operated on for one or more pheochromocytomas and/or paragangliomas and were submitted to F-DOPA PET/CT scan according to clinical, biochemical, or radiological suspicion of recurrence, while 3 were only genetically positive, with no previous symptom/sign of the disease. For all patients, biochemical analysis (plasma and/or urinary catecholamine) and results of high-resolution morphological imaging studies (CT and/or MRI) were available. Histologic/cytologic findings or imaging and biochemical follow-up were taken as gold standard in all cases.

RESULTS

Seven out of 10 patients showed one or more areas of pathological F-DOPA accumulation. PET/CT demonstrated the presence of the disease in 4/6 patients with no increase in catecholamine levels ("biochemically silent"). Positive detection rate was 100% in SDH-D and 40% in "non-SDHD". Analyzing per lesion, F-DOPA PET/CT demonstrated more lesions than anatomical imaging (16 vs. 7) especially in head and neck paragangliomas.

CONCLUSIONS

F-DOPA PET/CT seems to be the more accurate method for staging and restaging patients with SDH-mutations-related paraganglioma syndromes. F-DOPA is particularly useful in detecting head and neck and biochemically silent paragangliomas, and also in apparently healthy mutation-carrying people.

Experiences in the treatment of patients with multiple head and neck paragangliomas

PURPOSE

To analyze treatment results in the multidisciplinary management of patients with multiple head and neck paragangliomas (HNPs).

METHODS

Retrospective analysis including all patients with multiple HNPs (VP, vagal paraganglioma; JTP, jugulotympanic paraganglioma; CBT, carotid body tumor) treated between 2000 and 2013 at a tertiary referral center.

RESULTS

Ten patients (three men, seven women) had 25 HNPs (two VPs, eight JTPs, and 15 CBTs). The age range at diagnosis was 31-71 years (mean 40.9 years, median 37 years). Nine tumors (four CBTs, three JTPs, two VPs) were treated only with stereotactic radiotherapy (SRT; 50.4-56Gy, mean 55.3Gy) or in one case intensity-modulated radiotherapy (60 Gy). Nine tumors were treated with surgery alone (eight CBTs, one JTP) and three JTPs with subtotal surgery combined with adjuvant SRT. A "wait and scan" strategy was used in three cases (two CBTs, one JTP). The mean follow-up period was 4.3 years (range 0.1-13 years, median 4 years). The rate of tumor control with surgery and/or SRT was 100% (21/21). One patient with a wait-and-scan strategy for CBT had slow asymptomatic progression during a 13-year follow-up.

CONCLUSIONS

The treatment results in this series of patients with multiple HNPs show that a very high rate of long-term tumor control with low morbidity can be achieved using tailored and individualized approaches. All of the different treatment strategies available should be discussed with the patient. In particular, the treatment should involve a multidisciplinary team of experts in the fields of nuclear medicine, genetics, pathology, radiology, radio-oncology, and surgery.

Treatment of cervical paragangliomas: is surgery the only way?

PURPOSE

To analyze the results after surgery or stereotactic radiotherapy (SRT) in the treatment of cervical paragangliomas. Against this background, the decision-making algorithm used in the treatment of carotid body tumors (CBTs) and vagal paragangliomas (VPs) was reevaluated relative to the existing literature on the topic.

MATERIALS AND METHODS

Retrospective study between 2000 and 2012. A total of 27 CBTs and nine VPs in 32 patients were treated. Shamblin class I: 59.3% (n=16); class II: 29.6% (n=8); class III: 11.1% (n=3). Treatment modalities were surgery, radiotherapy, or observation. The end points for analysis were long-term tumor control and integrity of the cranial nerves.

RESULTS

21 CBTs and seven VPs underwent surgery; SRT was performed in three CBTs and two VPs. Three CBTs were clinically observed. Permanent nerve paresis followed after surgery for CBTs in five patients (20%) and in all patients with VPs. No impaired cranial nerve function resulted after SRT. The median follow-up period was 4.7 years. The tumor control rate after therapy for CBTs and VPs was 100%. One CBT that received clinical observation showed slow tumor progression.

CONCLUSIONS

A surgical procedure should be regarded as the treatment of choice in patients with small CBTs. In larger CBTs, particularly in elderly patients with unimpaired cranial nerves, radical surgery should be regarded critically. As surgery for VPs caused regularly impairment of cranial nerves with functional disturbances of various degrees a comprehensive consultation with the patient is mandatory and nonsurgical strategies should be discussed.

Pheochromocytoma: a review

Pheochromocytomas are catecholamine producing neuroendocrine tumors that can be adrenal or extra-adrenal in origin. The classic symptoms of pheochromocytoma are headache, palpitation, anxiety and diaphoresis and the tumor can occur at any age with equal gender distribution. In patients with an established mutation or hereditary syndrome the condition may manifest at a younger age than in those with sporadic disease. Pheochromocytoma can be associated with certain genetic syndromes such as multiple endocrine neoplasia type 2 (MEN 2), neurofibromatosis (NF) and von Hippel-Lindau (VHL) syndrome. Pheochromocytoma is diagnosed with biochemical confirmation of hormonal excess followed by anatomical localization (CT or MRI). The mainstay of definitive therapy is surgical resection. In this review, we discuss in detail about the symptomatology, diagnosis, genetic aspects and management of pheochromocytoma.

Diagnostic accuracy of (68)Ga-DOTANOC PET/CT imaging in pheochromocytoma

PURPOSE

The purpose of the present study was to evaluate the diagnostic accuracy of (68)Ga-DOTANOC positron emission tomography (PET)/CT in patients with suspicion of pheochromocytoma.

METHODS

Data of 62 patients [age 34.3 ± 16.1 years, 14 with multiple endocrine neoplasia type 2 (MEN2)] with clinical/biochemical suspicion of pheochromocytoma and suspicious adrenal lesion on contrast CT (n = 70), who had undergone (68)Ga-DOTANOC PET/CT, were retrospectively analyzed. PET/CT images were analyzed visually as well as semiquantitatively, with measurement of maximum standardized uptake value (SUVmax), SUVmean, SUVmax/SUVliver, and SUVmean/SUVliver. Results of PET/CT were compared with (131)I-metaiodobenzylguanidine (MIBG) imaging, which was available in 40 patients (45 lesions). Histopathology and/or imaging/clinical/biochemical follow-up (minimum 6 months) was used as reference standard.

RESULTS

The sensitivity, specificity, and accuracy of (68)Ga-DOTANOC PET/CT was 90.4, 85, and 88.7%, respectively, on patient-based analysis and 92, 85, and 90%, respectively, on lesion-based analysis. (68)Ga-DOTANOC PET/CT showed 100% accuracy in patients with MEN2 syndrome and malignant pheochromocytoma. On direct comparison, lesion-based accuracy of (68)Ga-DOTANOC PET/CT for pheochromocytoma was significantly higher than (131)I-MIBG imaging (91.1 vs 66.6%, p = 0.035). SUVmax was higher for pheochromocytomas than other adrenal lesions (p = 0.005), MEN2-associated vs sporadic pheochromocytoma (p = 0.012), but no difference was seen between benign vs malignant pheochromocytoma (p = 0.269).

CONCLUSION

(68)Ga-DOTANOC PET/CT shows high diagnostic accuracy in patients with suspicion of pheochromocytoma and is superior to (131)I-MIBG imaging for this purpose. Best results of (68)Ga-DOTANOC PET/CT are seen in patients with MEN2-associated and malignant pheochromocytoma.

18F-fluorodihydroxyphenylalanine in the diagnosis of neuroendocrine tumors

(18)F-fluorodihydroxyphenylalanine (FDOPA) is a powerful tool for the diagnosis and detection of neuroendocrine tumors when planning and monitoring surgical and oncologic therapies. Pheochromocytomas, paragangliomas, and medullary thyroid cancers especially are amenable to FDOPA imaging because of the high specific uptake of this amino acid analogue and excellent tumor-to-background contrast on PET/computed tomography.

Transurethral resection of bladder tumour (TURBT) as an optional treatment method on pheochromocytoma of the urinary bladder

Pheochromocytoma of the urinary bladder is rare. We have experienced a case of unexpected pheochromocytoma of the urinary bladder in a 45-year-old female. An ultrasonographic, computed tomography scan and cystoscopic examination showed a submucosal bladder mass. After transurethral resection of bladder tumour was performed, the bladder mass was confirmed as pheochromocytoma by a pathologist. After surgery, the patient underwent a subsequent pelvic magnetic resonance imaging, positron emission tomography and I(131)-methyliodobenzylguanidine (I(131)-MIBG). An image study showed no residual tumour sites and no lymphatic metastasis. The patient has had no tumour recurrence and no voiding symptoms 3 years after the surgery.

Current status and controversies in adrenal incidentalomas

Adrenal incidentalomas (AI) are serendipitously discovered lesions during abdominal imaging studies that need to be investigated for evidence of hormonal hypersecretion and/or malignancy. Because imaging modalities can reliably identify lesions that carry a high risk of malignancy, we focus on the identification of hypersecretory lesions and those with subclinical activity, particularly Cushing syndrome. Because diverse diagnostic tests and cut-offs are employed, the prevalence of hypersecretory AI varies widely, and there is controversy regarding their long-term sequelae. In this article we provide information regarding current radiological means to define the nature of AI, and the most appropriate biochemical tests for delineating hypersecretory states. We also discuss the duration and intensity of AI follow-up as well as the identification of AI that require specific therapeutic intervention.

Theranostics: evolution of the radiopharmaceutical meta-iodobenzylguanidine in endocrine tumors

Since 1981, meta-iodobenzylguanidine (MIBG), labeled with (131)I and later (123)I, has become a valuable agent in the diagnosis and therapy of a number of endocrine tumors. Initially, the agent located pheochromocytomas and paragangliomas (PGLs), both sporadic and familial, in multiple anatomic sites; surgeons were thereby guided to excisional therapies, which were previously difficult and sometimes impossible. The specificity in diagnosis has remained above 95%, but sensitivity has varied with the nature of the tumor: close to 90% for intra-adrenal pheochromocytomas but 70% or less for PGLs. For patients with neuroblastoma, carcinoid tumors, and medullary thyroid carcinoma, imaging with radiolabeled MIBG portrays important diagnostic evidence, but for these neoplasms, use has been primarily as an adjunct to therapy. Although diagnosis by radiolabeled MIBG has been supplemented and sometimes surpassed by newer scintigraphic agents, searches by this radiopharmaceutical remain indispensable for optimal care of some patients. The radiation imparted by concentrations of (131)I-MIBG in malignant pheochromocytomas, PGLs, carcinoid tumors, and medullary thyroid carcinoma has reduced tumor volumes and lessened excretions of symptom-inflicting hormones, but its value as a therapeutic agent is being fulfilled primarily in attacks on neuroblastomas, which are scourges of children. Much promise has been found in tumor disappearance and prolonged survival of treated patients. The experiences with therapeutic (131)I-MIBG have led to development of new tactics and strategies and to well-founded hopes for elimination of cancers. Radiolabeled MIBG is an exemplar of theranostics and remains a worthy agent for both diagnosis and therapy of endocrine tumors.

EANM 2012 guidelines for radionuclide imaging of phaeochromocytoma and paraganglioma

PURPOSE

Radionuclide imaging of phaeochromocytomas (PCCs) and paragangliomas (PGLs) involves various functional imaging techniques and approaches for accurate diagnosis, staging and tumour characterization. The purpose of the present guidelines is to assist nuclear medicine practitioners in performing, interpreting and reporting the results of the currently available SPECT and PET imaging approaches. These guidelines are intended to present information specifically adapted to European practice.

METHODS

Guidelines from related fields, issued by the European Association of Nuclear Medicine and the Society of Nuclear Medicine, were taken into consideration and are partially integrated within this text. The same was applied to the relevant literature, and the final result was discussed with leading experts involved in the management of patients with PCC/PGL. The information provided should be viewed in the context of local conditions, laws and regulations.

CONCLUSION

Although several radionuclide imaging modalities are considered herein, considerable focus is given to PET imaging which offers high sensitivity targeted molecular imaging approaches.

Pheochromocytoma: implications in tumorigenesis and the actual management

Pheochromocytomas and paragangliomas are rare neuroendocrine catecholamine producing tumors with varied clinical presentations, biochemistries and genetic makeup. These features outline the complexity and the difficulties in studying and understanding the oncogenesis of these tumors. The study of families with genetically inherited mutations in pheochromocytoma susceptibility genes has greatly enhanced our understanding of the pathophysiology and mechanisms of oncogenesis of the disease, and consequently changed our clinical approach. Several molecular pathways and mutations in their important regulatory proteins have been identified. Such mutations are responsible for the dysregulation of metabolic pathways involved in oxygen and nutrient sensing, apoptosis regulation, cell proliferation, migration and invasion. The knowledge derived from the study of these pathways will be fundamental in the future clinical management of these patients. As a rare disease that often masks its clinical presentation, the diagnosis is frequently missed and a high level of suspicion is required. Management of this disease requires a multidisciplinary team approach and will be discussed along with advances in its treatment.

Contemporary nuclear medicine imaging of neuroendocrine tumours

Neuroendocrine tumours (NETs) are rare, heterogeneous, and often hormonally active neoplasms. Nuclear medicine (NM) imaging using single photon- and positron-emitting radiopharmaceuticals allows sensitive and highly specific molecular imaging of NETs, complementary to anatomy-based techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Somatostatin-receptor scintigraphy is a whole-body imaging technique widely used for diagnosis, staging and restaging of NETs. The increasing availability of hybrid single-photon emission CT (SPECT)/CT cameras now offers superior accuracy for localization and functional characterization of NETs compared to traditional planar and SPECT imaging. The potential role of positron-emission tomography (PET) tracers in the functional imaging of NETs is also being increasingly recognized. In addition to 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG), newer positron-emitting radiopharmaceuticals such as (18)F-dihydroxyphenylalanine (DOPA) and (68)Ga-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) peptides, show promise for the future. This article will summarize the role of current and emerging radiopharmaceuticals in NM imaging of this rare but important group of tumours.

Adrenal neoplasms

Adenoma, myelolipoma, phaeochromocytoma, metastases, adrenocortical carcinoma, neuroblastoma, and lymphoma account for the majority of adrenal neoplasms that are encountered in clinical practice. A variety of imaging methods are available for evaluating adrenal lesions including ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine techniques such as meta-iodobenzylguanidine (MIBG) scintigraphy and positron-emission tomography (PET). Lipid-sensitive imaging techniques such as unenhanced CT and chemical shift MRI enable detection and characterization of lipid-rich adenomas based on an unenhanced CT attenuation of ≤ 10 HU and signal loss on opposed-phase compared to in-phase T1-weighted images, respectively. In indeterminate cases, an adrenal CT washout study may differentiate adenomas (both lipid-rich and lipid-poor) from other adrenal neoplasms based on an absolute percentage washout of >60% and/or a relative percentage washout of >40%. This is based on the principle that adenomas show rapid contrast washout while most other adrenal neoplasms including malignant tumours show slow contrast washout instead. ¹⁸F-2-fluoro-2-deoxy-d-glucose-PET (¹⁸FDG-PET) imaging may differentiate benign from malignant adrenal neoplasms by demonstrating high tracer uptake in malignant neoplasms based on the increased glucose utilization and metabolic activity found in most of these malignancies. In this review, the multi-modality imaging appearances of adrenal neoplasms are discussed and illustrated. Key imaging findings that facilitate lesion characterization and differentiation are emphasized. Awareness of these imaging findings is essential for improving diagnostic confidence and for reducing misinterpretation errors.

Clinical and imaging overview of functional adrenal neoplasms

Adrenal adenoma, adrenocortical carcinoma, pheochromocytoma and neuroblastoma are four discrete adrenal neoplasms that have the potential for functional activity. Functional adrenal neoplasms can secrete cortisol, aldosterone, sex hormones or catecholamines. These heterogeneous groups of tumors show varied biological behavior and clinical outcomes. These neoplasms are encountered with increasing clinical frequency as a result of an expansion in the volume of medical imaging carried out. The clinical presentation, including prognosis and treatment options, and the imaging features of these neoplasms are discussed. The key radiological observations of each of these neoplasms are shown using multimodality images. Familiarity with the clinical and imaging features of these neoplasms improves diagnosis, and facilitates appropriate clinical decision-making and patient management.

Diagnostic performance of 18F-dihydroxyphenylalanine positron emission tomography in patients with paraganglioma: a meta-analysis

PURPOSE

The aim of this study was to systematically review and conduct a meta-analysis of published data about the diagnostic performance of (18)F-dihydroxyphenylalanine (DOPA) positron emission tomography (PET) in patients with paraganglioma (PG).

METHODS

A comprehensive computer literature search of studies published through 30 June 2011 regarding (18)F-DOPA PET or PET/computed tomography (PET/CT) in patients with PG was performed in PubMed/MEDLINE, Embase and Scopus databases. Pooled sensitivity and specificity of (18)F-DOPA PET or PET/CT in patients with PG on a per patient- and on a per lesion-based analysis were calculated. The area under the receiver-operating characteristic (ROC) curve was calculated to measure the accuracy of (18)F-DOPA PET or PET/CT in patients with PG. Furthermore, a sub-analysis taking into account the different genetic mutations in PG patients was also performed.

RESULTS

Eleven studies comprising 275 patients with suspected PG were included in this meta-analysis. The pooled sensitivity of (18)F-DOPA PET and PET/CT in detecting PG was 91% [95% confidence interval (CI) 87-94%] on a per patient-based analysis and 79% (95% CI 76-81%) on a per lesion-based analysis. The pooled specificity of (18)F-DOPA PET and PET/CT in detecting PG was 95% (95% CI 86-99%) on a per patient-based analysis and 95% (95% CI 84-99%) on a per lesion-based analysis. The area under the ROC curve was 0.95 on a per patient- and 0.94 on a per lesion-based analysis. Heterogeneity between the studies about sensitivity of (18)F-DOPA PET or PET/CT was found. A significant increase in sensitivity of (18)F-DOPA PET or PET/CT was observed when a sub-analysis excluding patients with succinate dehydrogenase subunit B (SDHB) gene mutations was performed.

CONCLUSION

In patients with suspected PG (18)F-DOPA PET or PET/CT demonstrated high sensitivity and specificity. (18)F-DOPA PET or PET/CT are accurate methods in this setting. Nevertheless, possible sources of false-negative results should be kept in mind. Furthermore, SDHB gene mutations could influence (18)F-DOPA PET or PET/CT diagnostic performance.

Management of von Hippel-Lindau disease-associated CNS lesions

Patients with von Hippel-Lindau disease (VHL) often harbor significant disease burden within the CNS, specifically craniospinal-axis hemangioblastomas and endolymphatic sac tumors (ELSTs). The majority (60-80%) of patients with VHL harbor hemangioblastomas, and 10-15% will develop ELSTs. Advances in the understanding of the natural history and outcomes associated with the surgical management of VHL-associated tumors have led to improved management of patients with VHL. Optimizing indications for surgical intervention and refining of surgical techniques for these lesions can reduce patient morbidity associated with the management of this syndrome. In this article, we review the various aspects of perioperative management of patients with VHL, surgical indications and general operative principles for the management of hemangioblastomas and ELSTs, and outcomes associated with the surgical treatment of these tumors.