Adrenal phaeochromocytoma: correlation of MRI appearances with histology and function

Incidental detection of purely cystic pheochromocytoma in a young adult presenting with lower urinary tract infection

Pheochromocytoma is a rare neuroendocrine tumor arising from adrenal medulla. Patients usually show classic triad of headache, palpitations and diaphoresis along with persistent or paroxysmal hypertension. Majority of the tumors are solid or mixed solid and cystic. But purely cystic variant is extremely rare with few cases reports available in the published literature. We report a case of purely cystic pheochromocytoma in a male in 30s who presented to our hospital for unrelated symptom of recurrent burning micturition. He was evaluated for causes of recurrent UTI which revealed incidental right adrenal cyst. The patient's blood pressure was raised on clinical examination and imaging showed simple adrenal cyst without solid component or septations. Suspecting possibility of pheochromocytoma, biochemical analysis was done which revealed elevated 24-hour urinary metanephrine. The diagnosis of cystic pheochromocytoma was made. Adrenalectomy was performed showing cystic lesion in the right adrenal region. Histopathology and immunohistochemistry revealed pheochromocytoma with cystic degeneration. Patient's hypertension resolved during the follow up. In conclusion, purely cystic pheochromocytoma must be considered as differential for adrenal cystic lesions, especially when atypical features are present.

Case report: Imaging of adrenal adenomatoid tumors: reports of two cases and review of literature

Adenomatoid tumors (ATs) are uncommon, benign tumors of mesothelial origin, most frequently found in the genital tracts of both sexes. Extragenital localization sites, such as adrenal glands, are extremely rare. Since patients with adrenal ATs have no obvious clinical symptoms, imaging examination has become important evidence for diagnosis. Although previous literature noted that the imaging findings of adrenal ATs were nonspecific, no relevant studies have confirmed this. We herein present two novel cases of adrenal ATs, confirmed by immunohistochemistry, and that were initially misdiagnosed as other, more common adrenal tumors based on clinical findings and preoperative imaging. Including our cases, we collected a total of 33 previously reported adrenal ATs and extracted all available imaging information from them, aiming to find some radiological characteristics of this rare tumor. Through the review, we identified some nonspecific imaging features of adrenal ATs; however, the final diagnosis still depends on pathology and immunohistochemistry results.

Differentiation of pheochromocytoma and adrenal lipoid adenoma by radiomics: are enhanced CT scanning images necessary?

Purpose

To establish various radiomics models based on conventional CT scan images and enhanced CT images, explore their value in the classification of pheochromocytoma (PHEO) and lipid-poor adrenal adenoma (LPA) and screen the most parsimonious and efficient model.

Methods

The clinical and imaging data of 332 patients (352 lesions) with PHEO or LPA confirmed by surgical pathology in the Affiliated Hospital of Qingdao University were retrospectively analyzed. The region of interest (ROI) on conventional and enhanced CT images was delineated using ITK-SNAP software. Different radiomics signatures were constructed from the radiomics features extracted from conventional and enhanced CT images, and a radiomics score (Rad score) was calculated. A clinical model was established using demographic features and CT findings, while radiomics nomograms were established using multiple logistic regression analysis.The predictive efficiency of different models was evaluated using the area under curve (AUC) and receiver operating characteristic (ROC) curve. The Delong test was used to evaluate whether there were statistical differences in predictive efficiency between different models.

Results

The radiomics signature based on conventional CT images showed AUCs of 0.97 (training cohort, 95% CI: 0.95∼1.00) and 0.97 (validation cohort, 95% CI: 0.92∼1.00). The AUCs of the nomogram model based on conventional scan CT images and enhanced CT images in the training cohort and the validation cohort were 0.97 (95% CI: 0.95∼1.00) and 0.97 (95% CI: 0.94~1.00) and 0.98 (95% CI: 0.97∼1.00) and 0.97 (95% CI: 0.94∼1.00), respectively. The prediction efficiency of models based on enhanced CT images was slightly higher than that of models based on conventional CT images, but these differences were statistically insignificant(P>0.05).

Conclusions

CT-based radiomics signatures and radiomics nomograms can be used to predict and identify PHEO and LPA. The model established based on conventional CT images has great identification and prediction efficiency, and it can also enable patients to avoid harm from radiation and contrast agents caused by the need for further enhancement scanning in traditional image examinations.

Diagnostic performance of magnetic resonance imaging features to differentiate adrenal pheochromocytoma from adrenal tumors with positive biochemical testing results

BACKGROUND

It is extremely essential to accurately differentiate pheochromocytoma from Adrenal incidentalomas (AIs) before operation, especially biochemical tests were inconclusive. We aimed to evaluate the value of magnetic resonance imaging (MRI) features to differentiate pheochromocytomas among adrenal tumors, among which the consequences of biochemical screening tests of catecholamines and/or catecholamine metabolites are positive.

METHODS

With institutional review board approval, this study retrospectively compared 35 pheochromocytoma (PHEO) patients with 27 non-pheochromocytoma(non-PHEO) patients between January 2022 to September 2023, among which the consequences of biochemical screening tests of catecholamines and/or catecholamine metabolites are positive. T test was used for the independent continuous data and the chi-square test was used for categorical variables. Univariate and multivariate logistic regression were applied to find the independent variate of the features to differentiate PHEO from non-PHEO and ROC analysis was applied to evaluate the diagnostic value of the independent variate.

RESULTS

We found that the T2-weighted (T2W) signal intensity in patients with pheochromocytoma was higher than other adrenal tumors, with greatly significant (p < 0.001). T2W signal intensity ratio (T2W nodule-to-muscle SI ratio) was an independent risk factor for the differential diagnosis of adrenal PHEOs from non-PHEOs. This feature alone had 91.4% sensitivity and 81.5% specificity to rule out pheochromocytoma based on optimal threshold, with an area under the receiver operating characteristics curve (AUC‑ROC) of 0.910(95% C I: 0.833-0.987).

CONCLUSION

Our study confirms that T2W signal intensity ratio can differentiate PHEO from non-PHEO, among which the consequences of biochemical screening tests of catecholamines and/or catecholamine metabolites are positive.

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.

Preoperative management of patients with ectopic Cushing's syndrome caused by ACTH-secreting pheochromocytoma: a case series and review of the literature

PURPOSE

ACTH-secreting pheochromocytoma is a rare cause of ectopic Cushing's syndrome, posing a clinical challenge for the severity of its clinical presentation, the difficulty in the prevention and the management of surgical complications. Sparse data are currently available about the optimal preoperative management of the severe symptoms due to both hypercortisolism and catecholamine excess, especially regarding the role and timing of medical therapies.

METHODS

We present a series of three patients with ACTH-secreting pheochromocytoma. A brief review of the available literature evidence on the preoperative management of this rare clinical condition is also conducted.

DISCUSSION

Patients with ACTH-secreting pheochromocytoma show peculiarities as compared to other forms of ACTH-dependent Cushing's syndrome, in terms of clinical presentation, preoperative management, and peri- and post-surgical short-term outcome. Pheochromocytoma should be ruled out in patient with ectopic CS of unknown origin because of the high anesthesiologic risk of proceeding to surgery with an undiagnosed pheochromocytoma. Proper preoperative recognition of complications of both hypercortisolism and catecholamines excess is the key to prevent the morbidity and mortality of an ACTH-producing pheochromocytoma. In these patients the absolute priority is to control excessive cortisol secretion since the rapid correction of the hypercortisolism is the most effective treatment of all the related comorbidities and it is mandatory to prevent severe complications during surgery, opting if necessary for a "block-and-replace" regimen.

CONCLUSION

Our additional cases and this literature review could provide a better understanding of the complications to be evaluated at diagnosis and some suggestions on their management during the preoperative period.

A complementary comment on primary hepatic angiosarcoma: A case report

BACKGROUND

This article examines primary hepatic angiosarcoma (PHA) and fat-poor angiomyolipoma (AML), two uncommon vascular cancers. Clinical decisions in these situations are frequently aided by pathology reports and imaging techniques. Uncommon malignant tumors of the vascular endothelium include PHA. Another diagnosis that should not be overlooked when employing contrast-enhanced MR and contrast-enhanced computed tomography (CT) imaging techniques is fat-poor AML, one of the uncommon vascular tumors of the liver. In both conditions, biopsy is the primary means of diagnosis.

CASE SUMMARY

In our article, besides the diagnosis of PHA, fat-poor AML, one of the other rare vascular tumors of the liver, is mentioned. In the case, a 50-year-old female patient with VHL Syndrome was admitted to our hospital with nonspecific lesions such as right upper quadrant pain, weight loss, and nausea. Abdominal ultrasonography (US) revealed a hypoechoic heterogeneous lesion with occasional faint contours. In computed tomography, it was observed as a hyperdense nodular lesion in segment 4. Magnetic resonance imaging (MRI) revealed that the lesion did not contain fat. In connection with the known history of VHL Syndrome, we first evaluated the possibility of AML. Thereupon, a histopathological sample was taken and the diagnosis was made as fat-poor AML with 5% fat content.

CONCLUSION

In conclusion, PHA in our case report and fat-poor AML in our clinic are two uncommon liver vascular malignancies with comparable incidences. Important imaging techniques like contrast-enhanced US (CEUS), CECT, and CEMRI give us substantial advantages in both cases. However, a biopsy is used to provide the final diagnosis.

Imaging incidental adrenal lesions

Incidental adrenal masses are among the most common incidental lesions detected on cross-sectional imaging. The majority are benign lesions, adenomas and myelolipomas being the most common. Simple cross-sectional imaging techniques using CT and MRI permit the characterization of over 80%, thereby requiring no further imaging. The remaining lesions are considered indeterminate. These lesions consist of benign and malignant lesions sharing imaging features. Further imaging and management of these indeterminate lesions should be guided by close collaboration between different specialists in an MDT setting. Advanced imaging options include dedicated adrenal scintigraphy, positron emission tomography CT, biopsy and surveillance. Biochemical and hormonal evaluation is also important to identify hyperfunctioning adrenal lesions. This review focuses on imaging features of benign and malignant adrenal masses used for characterization and suggests an imaging pathway for indeterminate adrenal masses.

Imaging Recommendations for Diagnosis, Staging, and Management of Adrenal Tumors

Adrenal glands are affected by a wide variety of tumors apart from infective and inflammatory lesions and their noninvasive characterization on imaging is important for the management of these patients. Incidentalomas form the major bulk of adrenal tumors and differentiation of benign adenomas from other malignant lesions, especially in patients with a known malignancy, guide further management. Imaging is an integral part of management along with clinical and biochemical features. The cornerstone of clinical and biochemical evaluation of adrenal tumors is to determine whether the lesion is functional or nonfunctional. Computed tomography (CT) is considered as the workhorse for imaging evaluation of adrenal lesions. CT densitometry and CT contrast washout characteristics are quite reliable in differentiating adenomas from malignant lesions. CT is also the modality of choice for the evaluation of resectability and staging of primary adrenal tumors. Magnetic resonance imaging (MRI) has superior contrast resolution compared to other morphological imaging modalities and is generally used as a problem-solving tool. MRI chemical shift imaging can also be used to reliably detect adrenal adenomas. Ultrasonography (USG) is used as a screening tool that is usually followed by either CT or MRI to better characterize the tumor and it is not routinely used for assessing the resectability, staging, and characterization of adrenal tumors. Another important role of USG is in image-guided sampling of tumors. Fluorodeoxyglucose positron emission tomography-computed tomography and other nuclear medicine modalities are a valuable addition to morphological imaging modalities. Image-guided interventions also play an important role in obtaining tissue samples where diagnostic imaging is not able to characterize adrenal tumors. In the functioning of adrenal tumors, adrenal venous sampling is widely used to accurately lateralize the secreting tumor.

Imaging manifestations of von Hippel-Lindau disease: an illustrated guide focusing on abdominal manifestations

Von Hippel-Lindau (VHL) disease is a monogenic autosomal dominant disorder with germline mutations of the VHL anti-oncogene on the short arm of chromosome 3 (3p25-26). It affects 1:36,000-50,000 individuals, with a penetrance greater than 90% at 65 years of age. Although of variable onset and presentation, with pleiotropism even among members of the same family who share a specific mutation, VHL disease usually manifests initially in young adults. It predisposes to the development of benign and malignant tumors of the central nervous system (CNS) and visceral organs. The clinical diagnosis of VHL disease can be made in the following circumstances: a) in patients with a family history of the disease and at least one of the tumors characteristic of it (e.g., retinal or CNS hemangioblastomas, clear cell renal cell carcinoma, pancreatic neuroendocrine tumors, and endolymphatic sac tumors); b) in patients with two or more CNS hemangioblastomas; c) or in patients with a retinal or CNS hemangioblastoma plus at least one visceral tumor characteristic of the disease, excluding renal and epididymal cysts. Imaging plays an important role in the diagnosis and follow-up of patients with VHL disease. This pictorial essay presents characteristic images of abdominal manifestations of VHL disease-related tumors that all radiologists should be aware of.

Manifestações de imagem da doença de von Hippel-Lindau: um guia ilustrado das manifestações abdominais

Resumo A doença de von Hippel-Lindau (VHL) é uma desordem autossômica dominante monogênica com mutações na linha germinativa do antioncogene VHL, no braço curto do cromossomo três (3p25-26). Afeta 1:36.000-50.000 indivíduos, com penetrância superior a 90% aos 65 anos de idade. Embora tenha início e apresentação variáveis, com pleiotropismo mesmo entre membros da mesma família que partilham uma mutação específica, usualmente manifesta-se de início em adultos jovens e predispõe ao desenvolvimento de tumores benignos e malignos no sistema nervoso central (SNC) e órgãos viscerais. Clinicamente, o diagnóstico pode ser realizado em uma das seguintes circunstâncias: a) em pacientes com história familiar de doença de VHL e pelo menos um dos tumores característicos relacionados à síndrome (como hemangioblastomas retinianos ou do SNC, carcinoma de células renais de células claras, tumores neuroendócrinos pancreáticos e tumores do saco endolinfático); b) dois ou mais hemangioblastomas do SNC; c) um hemangioblastoma retiniano ou do SNC mais pelo menos um tumor característico visceral relacionado à síndrome, excluindo-se cistos renais e epididimários. Nesse contexto, a imagem ocupa importante papel no diagnóstico e acompanhamento desses pacientes. Este ensaio iconográfico apresenta imagens características de manifestações abdominais de tumores relacionados à doença de VHL que todos os radiologistas devem conhecer.

Bladder paragangliomas: a pictorial review

Bladder paragangliomas (bPGL) are rare neuroendocrine tumors arising from the sympathetic paraganglia present in the bladder wall. Bladder PGLs are typically submucosal or intramural but when subserosal may not be readily visible at cystoscopy. The average size at presentation is 3.9 cm (range 1.0-9.1 cm). When small, bPGL are usually spherical, well-marginated and homogeneous. Larger bPGL are typically more complex with peri- and intra-tumoral neovascularity and central necrosis. On ultrasound, increased color Doppler signal is typical. The increased soft tissue resolution of MRI enables localization of bPGL within the bladder wall more accurately than CT. Restricted diffusion and avid contrast enhancement help differentiate small bPGLs from leiomyomas, which have similar appearances on ultrasound and CT. Nuclear medicine techniques identify bPGLs and their metastases with high specificity, ⁶⁸Ga-DOTATATE PET/CT having largely replaced ¹²³I-mIBG SPECT/CT as the first line functional investigation. Imaging is essential to aid surgical planning, as endoscopic resection is often not possible or incomplete due to tumor location. For patients with advanced disease, ⁶⁸Ga-DOTATATE PET/CT and ¹²³I-mIBG SPECT/CT assess suitability for peptide receptor radionuclide therapy. Up to 63% of bPGL patients have a germline mutation, most commonly in the SDHB subunit gene, increasing their risk of developing pheochromocytomas and further paragangliomas; lifelong annual biochemical and periodic imaging screening from skull base to pelvis is therefore recommended.

Major intraoperative bleeding and drastic change in circulatory dynamics in a pregnant patient with metastatic pheochromocytoma: a case report

BACKGROUND

Metastatic pheochromocytoma in the spine is a very rare complication during pregnancy. We report anesthesia in a pregnant woman for resection of an undiagnosed spinal tumor, accompanied by remarkable hemodynamic changes and massive bleeding.

CASE PRESENTATION

A 33-year-old woman at 17 weeks of gestation presented with the rapid progress of bilateral lower leg paralysis. A diagnosis of spinal tumor was made, and surgical resection was planned. Although the surgery was suspended because of remarkable hemodynamic changes and massive bleeding, fetal heart rate was stable. Postoperative examination revealed pheochromocytoma in the urinary bladder as a primary lesion with spinal metastasis.

CONCLUSION

Although spinal pheochromocytoma is extremely rare in pregnant women, it should be suspected when abnormal hypertension is observed with accompanying neurological deficits. Preservation of maternal circulation and uteroplacental blood flow should be the first priority during anesthesia.

Predictive model of pheochromocytoma based on the imaging features of the adrenal tumours

The purpose of our study was to develop a predictive model to rule out pheochromocytoma among adrenal tumours, based on unenhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) features. We performed a retrospective multicentre study of 1131 patients presenting with adrenal lesions including 163 subjects with histological confirmation of pheochromocytoma (PHEO), and 968 patients showing no clinical suspicion of pheochromocytoma in whom plasma and/or urinary metanephrines and/or catecholamines were within reference ranges (non-PHEO). We found that tumour size was significantly larger in PHEO than non-PHEO lesions (44.3 ± 33.2 versus 20.6 ± 9.2 mm respectively; P < 0.001). Mean unenhanced CT attenuation was higher in PHEO (52.4 ± 43.1 versus 4.7 ± 17.9HU; P < 0.001). High lipid content in CT was more frequent among non-PHEO (83.6% versus 3.8% respectively; P < 0.001); and this feature alone had 83.6% sensitivity and 96.2% specificity to rule out pheochromocytoma with an area under the receiver operating characteristics curve (AUC-ROC) of 0.899. The combination of high lipid content and tumour size improved the diagnostic accuracy (AUC-ROC 0.961, sensitivity 88.1% and specificity 92.3%). The probability of having a pheochromocytoma was 0.1% for adrenal lesions smaller than 20 mm showing high lipid content in CT. Ninety percent of non-PHEO presented loss of signal in the “out of phase” MRI sequence compared to 39.0% of PHEO (P < 0.001), but the specificity of this feature for the diagnosis of non-PHEO lesions low. In conclusion, our study suggests that sparing biochemical screening for pheochromocytoma might be reasonable in patients with adrenal lesions smaller than 20 mm showing high lipid content in the CT scan, if there are no typical signs and symptoms of pheochromocytoma.

Adrenal Mass Characterization in the Era of Quantitative Imaging: State of the Art

Simple Summary

Non-invasive characterization of adrenal lesions requires a rigorous approach. Although CT is the cornerstone of adrenal lesion characterization, a multimodality multiparametric imaging approach helps improve confidence in adrenal lesion characterization.

Abstract

Detection and characterization of adrenal lesions have evolved during the past two decades. Although the role of imaging in adrenal lesions associated with hormonal secretion is usually straightforward, characterization of non-functioning adrenal lesions may be challenging to confidently identify those that need to be resected. Although many adrenal lesions can be readily diagnosed when they display typical imaging features, the diagnosis may be challenging for atypical lesions. Computed tomography (CT) remains the cornerstone of adrenal imaging, but other morphological or functional modalities can be used in combination to reach a diagnosis and avoid useless biopsy or surgery. Early- and delayed-phase contrast-enhanced CT images are essential for diagnosing lipid-poor adenoma. Ongoing studies are evaluating the capabilities of dual-energy CT to provide valid virtual non-contrast attenuation and iodine density measurements from contrast-enhanced examinations. Adrenal lesions with attenuation values between 10 and 30 Hounsfield units (HU) on unenhanced CT can be characterized by MRI when iodinated contrast material injection cannot be performed. ¹⁸F-FDG PET/CT helps differentiate between atypical benign and malignant adrenal lesions, with the adrenal-to-liver maximum standardized uptake value ratio being the most discriminative variable. Recent studies evaluating the capabilities of radiomics and artificial intelligence have shown encouraging results.

Characterization of Atypical Pheochromocytomas with Correlative MRI and Planar/Hybrid Radionuclide Imaging: A Preliminary Study

Pheochromocytomas may show atypical imaging findings leading to diagnostic pitfalls. We correlated the results of magnetic resonance imaging (MRI) with those of radionuclide studies in patients with pheochromocytomas. T2-weighted (-w), T1-w chemical-shift and T1-w dynamic contrast enhanced (DCE) MRI sequences were evaluated to assess tumor structure. 131Iodine metaiodobenzylguanidine (MIBG) scintigraphy, 18fluoro (F) deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) or FDG PET/MRI were evaluated for direct comparison. Of a total of 80 adrenal lesions in 73 patients, 20 in 18 patients were pheochromocytomas. More than half (55%) of the pheochromocytomas (n = 11) had the typical increased signal intensity on T2-w and T1-w DCE, while the remaining (n = 9) lesions showed atypical findings; of these nine latter atypical lesions, seven (35%) were cystic (two totally, three predominantly and two partially) and two (10%) were hemorrhagic on MRI. In these atypical lesions, MIBG scintigraphy (n = 5), FDG PET/CT (n = 6) or FDG PET/MRI (n = 2) showed inhomogeneous tracer uptake in the residual viable tissue providing tumor characterization; however, one predominantly cystic pheochromocytoma showed false negative MIBG scan. Our preliminary results show that cystic degeneration may be frequent in pheochromocytoma being so marked that only a thin rim of viable cells may residue to disclose the true nature of the tumor. MRI findings together with those of correlative planar/hybrid radionuclide images are helpful to characterize these atypical pheochromocytomas. In particular, tumor accumulation of MIBG and/or FDG is able to classify these lesions as not simple cysts; in detail, the presence of partial MIBG uptake allows the diagnosis of pheochromocytomas, while the presence of partial FDG uptake generically reflects the presence of viable solid tissue of such cystic tumors.

Adrenal pheochromocytoma: is it all or the tip of the iceberg?

Adrenal pheochromocytoma is not always a simple retroperitoneal tumor but may be part of a more complicated condition. It often has a spectrum of complex and variable imaging features, may present as a collision tumor and composite tumor, and is associated with a variety of clinical syndromes. A comprehensive understanding of the clinical, pathological, and variable imaging manifestations of pheochromocytoma can help radiologists make an accurate diagnosis. This article reviews various special imaging features of pheochromocytoma and pheochromocytoma-related diseases.

[Adrenal imaging: anatomy and pathology (literature review)]

This literature review focuses on the normal adrenal gland anatomy and typical imaging features necessary to evaluate benign and malignant lesions. In particular, adenoma, pheochromocytoma, metastases and adrenocortical carcinoma were discussed as some of the most common lesions. For this purpose, a review of relevant local and international literature sources up to January 2021 was conducted.In many cases, adrenal incidentalomas have distinctive features allowing characterization using noninvasive methods. It is possible to suspect a malignant nature and promptly refer the patient for the necessary invasive examinations in some cases. -Computed tomography, especially with intravenous contrast enhancement, is the primary imaging modality because it enables differential diagnosis. Magnetic resonance tomography remains a sensitive method in lesion detection and follow-up but is not very specific for determining the malignant potential. Positron emission computed tomography also remains an additional method and is used mainly for differential diagnosis of malignant tumors, detecting metastases and recurrences after surgical treatment. Ultrasound has a limited role but is nevertheless of great importance in the pediatric population, especially newborns. Promising techniques such as radiomics and dual-energy CT can expand imaging capabilities and improve diagnostic accuracy.Because adrenal lesions are often incidentally detected by imaging performed for other reasons, it is vital to interpret such findings correctly. This review should give the reader a broad overview of how different imaging modalities can evaluate adrenal pathology and guide radiologists and clinicians.

Contrast-enhanced ultrasound in evaluation of adrenal lesions with CT/MRI correlation

Most of the adrenal masses are incidentally detected. Multiphasic CT forms the mainstay for diagnosis and characterization of adrenal masses. MRI can further be used if the masses are indeterminate on CT scan. But as these investigations are expensive with risk of radiation exposure, contrast-enhanced ultrasound (CEUS) is currently under evaluation to assess its utility to act as a screening modality to differentiate benign vs malignant adrenal masses This investigative modality is relatively safe and can be used in patients having renal dysfunction or allergy to CT contrast. We, hereby, present a pictorial review of imaging appearance of various adrenal lesions on CEUS with CT and MRI correlation.

Pitfalls and differential diagnosis on adrenal lesions: current concepts in CT/MR imaging: a narrative review

The purpose of this pictorial essay is to review the imaging findings of adrenal lesions. Adrenal lesions could be divided into functioning or non-functioning masses, primary or metastatic, and benign or malignant. Imaging techniques have undergone significant advances in recent years. The most significant objective of adrenal imaging is represented by the detection and, when possible, characterization of adrenal lesions in order to direct patient management correctly. The detection and management of adrenal lesions is based on cross-sectional imaging obtained with non-contrast CT (tumour density), contrast-enhanced CT including delayed washout (either absolute percentage washout or relative percentage one) and finally with MR chemical shift analysis (loss of signal intensity between in-phase and out-of-phase images including both qualitative and quantitative estimates of signal loss). The small incidental adrenal nodules are benign, in most of cases; some tumors such as lipid-rich adenoma and myelolipoma have characteristic features that can be diagnosed accurately in CT. On contrary, if the presenting contrast-enhanced CT shows an adrenal mass with uncertain or malignant morphologic features, particularly in patients with a known history of malignancy, further evaluations should be considered. The most significative implications for radiologists are represented by how to assess risk of malignancy on imaging and what follow-up to indicate if an adrenal incidentaloma is not surgically removed.

False iodine-131 MIBG scintigraphy findings in adrenal tumors: correlation with MR imaging

In this study, we report our experience regarding the occurrence of false radionuclide findings in adrenal iodine-131 MIBG scintigraphy. We present a total of five patients in which nuclear images were false negative or positive in three and two cases, respectively, according to the standard radionuclide established criteria. In particular, the three cases of false-negative MIBG images consisted of two patients with necrotic or cystic pheochromocytomas (Cases 1 and 3) and a patient with a small pheochromocytoma (Case 2); the two cases of false-positive MIBG imaging consisted of a patient with an adenoma showing intense tracer uptake and of a large primary necrotic carcinoma with heterogeneous tracer concentration.

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: Spectrum of Abdominal Manifestations

OBJECTIVE. Multiple endocrine neoplasia (MEN) syndromes are autosomal-dominant genetic disorders that predispose two or more organs of the endocrine system to tumor development. Although the diagnosis relies on clinical and serologic findings, imaging provides critical information for surgical management with the ultimate goal of complete tumor resection. CONCLUSION. This article reviews abdominal neoplasms associated with the various subtypes of MEN syndromes, with a focus on clinical presentation and characteristic imaging features.

Imaging Features of Succinate Dehydrogenase-deficient Pheochromocytoma-Paraganglioma Syndromes

Pheochromocytoma (PC) and paraganglioma (PGL) are rare neuroendocrine tumors that occur throughout the body from the base of the skull to the pelvis. Sympathetic catecholamine-secreting tumors may be associated with hyperadrenergic symptoms and long-term morbidity if they are untreated. Typically biochemically silent, head and neck PGLs may result in cranial nerve palsies and symptoms due to localized mass effect. Tumors can arise sporadically or as part of an inheritable PC-PGL syndrome. Up to 40% of tumors are recognized to be associated with germline mutations in an increasing array of susceptibility genes, including those that appear to arise sporadically. Most commonly, up to 25% of all PC-PGLs are associated with mutations in one of the succinate dehydrogenase (SDH) enzyme subunit genes. The resulting familial PC-PGL syndrome varies according to the affected enzyme subunit (most commonly SDHB and SDHD mutations) with respect to tumor prevalence, location, age of onset, and risk of malignancy. Patients with SDH enzyme mutations have increased lifetime risk of developing multifocal tumors and malignancy. Early recognition of individuals at high risk, genetic testing, screening of family members, and lifelong surveillance programs are recommended, but not without health, economic, and psychologic implications. Anatomic and functional imaging is key to diagnosis, staging, treatment planning, and lifelong surveillance of these individuals. Radiologists must be aware of the imaging appearance of these varied tumors.^©RSNA, 2019.

Internal validation and decision curve analysis of a preoperative nomogram predicting a postoperative complication in pheochromocytoma surgery: An international study

OBJECTIVES

To develop a preoperative nomogram that would predict the risk of a postoperative complication for pheochromocytoma patients undergoing adrenalectomy using an international database.

METHODS

We retrospectively analyzed preoperative variables and postoperative outcomes in patients who underwent adrenalectomy for pheochromocytoma in three institutions from 2000 to 2017. Internal validation of a generated nomogram was carried out with receiver operating characteristics, calibration plots, and decision curve analyses.

RESULTS

A total of 153 patients who had undergone 166 adrenalectomies were included in the study. Overall, post-adrenalectomy complications were seen in 30% of patients, whereas 9.6% of patients sustained a Clavien ≥3a complication. Independent predictors of a complication were a history of hypertension, body mass index, tumor size, and Charlson Comorbidity Index score. On internal validation, the multivariable model generated a nomogram that predicted a postoperative complication or clinically hemodynamic event with an area under the curve of 0.86, showed good calibration and had an overall net benefit.

CONCLUSIONS

An internally validated nomogram combining body mass index, Charlson Comorbidity Index score and tumor size can predict the probability of a post-adrenalectomy complication in those with and without hypertension. The model, the first of its kind in pheochromocytoma surgery, identifies patients at risk of a postoperative complication at the time of their presentation with pheochromocytoma.

Combined Diagnosis of Whole-Lesion Histogram Analysis of T1- and T2-Weighted Imaging for Differentiating Adrenal Adenoma and Pheochromocytoma: A Support Vector Machine-Based Study

PURPOSE

This study aimed to determine whether a combined diagnosis of whole-lesion histogram analysis of T1- and T2-weighted imaging based on support vector machine (SVM) can distinguish pheochromocytoma from adrenal adenoma.

METHODS

A pathology database was retrospectively appraised over a period of 7 years and we obtained 40 histopathologically proven adrenal adenomas and 20 pheochromocytomas with magnetic resonance images. The T1-weighted imaging (T₁WI, including both in phase and opposed phase) and T2-weighted imaging (T₂WI) images of each patients were analyzed using Mazda software. Nine parameters were selected as indicators of comparison: variance, skewness, kurtosis, mean, 1st percentile, 10th percentile, 50th percentile, 90th percentile, and 99th percentile. The parameters with differential-diagnosis significance were used to establish the combined diagnostic model of SVM.

RESULTS

Among the 9 parameters extracted using histogram analysis, the 1st percentile, 10th percentile, and 50th percentile of T₁WI (in phase) and the skewness of T₂WI and almost all parameters of T₁WI (opposed phase), except variance and 99th percentile, showed statistical significance between groups. Among the above parameters, the area under the curve (AUC) of 10th percentile of T₁WI (opposed phase) was the largest with the value of 0.909 (100.0% sensitivity and 80.0% specificity). After the analysis of combined diagnosis was performed, the AUC of SVM model in testing set showed the value of 0.917 (85.0% accuracy).

CONCLUSIONS

Whole-lesion histogram analysis of T₁WI and T₂WI may help differentiate adrenal adenomas from pheochromocytomas. Furthermore, the combined diagnosis of T₁WI and T₂WI histogram based on SVM was more effective than most of individual histogram parameters.

Pheochromocytoma: An approach to diagnosis

Pheochromocytomas are rare neuroendocrine chromaffin-derived tumors that arise within the adrenal medulla. They are usually benign, but if not diagnosed or if left untreated, they can have devastating consequences. Clinical consideration of the diagnosis is paramount, as they may have protean manifestations, and a high index of suspicion is essential if serious consequences are to be avoided. An accurate biochemical diagnosis is crucial for the management of these patients: either plasma or urinary metanephrines are both highly sensitive and specific if correctly employed, but knowledge of pre- and post-analytic interference is essential. Diagnostic imaging with cross-sectional CT and/or MRI offers high sensitivity in their detection, but lack specificity. The introduction of PET/CT/MR has led to a dramatic improvement in the localization of both pheochromocytomas and paragangliomas, together with the increasing availability of new functional imaging radionuclides. Optimal investigation and accurate diagnosis is best achieved at 'centers of excellence' with expert multidisciplinary teams.

Precision Surgery for Pheochromocytomas and Paragangliomas

Since Felix Fränkel's account of pheochromocytoma in 1886, great discoveries and vast advancements in the diagnosis, genetics, anatomical and functional imaging techniques, and surgical management of pheochromcytoma and paraganglioma (P-PGL) have been made. The improved insight in the pathophysiology of P-PGL and more accurate detection methods enable physicians to tailor the treatment plan to an individual based on the genetic profile and tumor behavior. This review will cover briefly the clinical features, diagnosis, genetic mutations, and imaging modalities that are used to guide current surgical management of these rare and interesting endocrinopathies.

Imaging features of adrenal masses

The widespread use of imaging examinations has increased the detection of incidental adrenal lesions, which are mostly benign and non-functioning adenomas. The differentiation of a benign from a malignant adrenal mass can be crucial especially in oncology patients since it would greatly affect treatment and prognosis. In this setting, imaging plays a key role in the detection and characterization of adrenal lesions, with several imaging tools which can be employed by radiologists. A thorough knowledge of the imaging features of adrenal masses is essential to better characterize these lesions, avoiding a misinterpretation of imaging findings, which frequently overlap between benign and malignant conditions, thus helping clinicians and surgeons in the management of patients. The purpose of this paper is to provide an overview of the main imaging features of adrenal masses and tumor-like conditions recalling the strengths and weaknesses of imaging modalities commonly used in adrenal imaging.

MIBG (metaiodobenzylguanidine) theranostics in pediatric and adult malignancies

Metaiodobenzylguanidine, a guanithidine analog, labeled with ¹²³I and ¹³¹I, is used for imaging and therapy of neuroblastomas and various neural crest tumors like paragangliomas, pheochromocytomas, medullary cancer of thyroid and carcinoids since the past three to four decades. In this review article, we shall revisit metaiodobenzylguanidine as a radiopharmaceutical and its various applications in neural crest tumors.

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

CONTEXT

Diagnosis of paragangliomas (PGL) and phaeochromocytomas (PC) can be challenging particularly if the tumour is small. Detection of metastatic disease is important for comprehensive management of malignant PC/PGL. Somatostatin receptor imaging (SRI) agents have high sensitivity for these tumours, particularly the DOTA family of radiopharmaceuticals labelled with ⁶⁸ Gallium.

OBJECTIVE

To describe the utility of SRI in primary assessment (ie before surgery) for PC/PGL and whether measures of maximum standardized uptake (SUVmax) could be used to distinguish between adrenal adenomas and PCs.

DESIGN

Retrospective analysis of patients with PC and PGL between 2012 and 2017.

PATIENTS

Somatostatin receptor imaging (SRI) was performed for suspected PC (n = 46) or PGL (n = 27) of which 36 were during primary assessment and 37 during secondary assessment (follow-up after surgery). For comparison of adrenal SUVmax, scans from 30 patients without suspected PC/PGL (20 with normal adrenals; 10 with incidental adenomas) were evaluated.

MEASUREMENTS

Baseline description, sensitivity, specificity, Youden's index.

RESULTS

Sensitivity of DOTATATE-PET was 88% for PC and 100% for PGL. False-negative scans were seen in 2/10 PCs < 28 mm and in 1/14 PCs > 28 mm which had features of cystic degeneration. SUVmax of PCs and PGLs was more than double compared to adrenal adenomas (P > .001).

CONCLUSION

Somatostatin receptor imaging (SRI) has high sensitivity in primary assessment for PC and PGL. We recommend that SRI should be performed as part of primary assessment in all suspected PGLs (due to higher risk of multifocal lesions) and in PCs suspected to be associated with hereditary syndromes or metastases.

Current diagnostic imaging of pheochromocytomas and implications for therapeutic strategy

The topic of pheochromocytomas is becoming increasingly popular as a result of major advances in different medical fields, including laboratory diagnosis, genetics, therapy, and particularly in novel advances in imaging techniques. The present review article discusses current clinical, biochemical, genetic and histopathological aspects of the diagnosis of pheochromocytomas and planning of pre-surgical preparation and subsequent surgical treatment options. The main part of the paper is focused on the role of morphological imaging methods (primarily computed tomography and magnetic resonance imaging) and functional imaging (scintigraphy and positron emission tomography) in the diagnosis and staging of pheochromocytomas.

Cardiovascular Manifestations of Pheochromocytoma

Pheochromocytomas are rare endocrine tumors that can have a significant impact on a variety of organ systems, including the cardiovascular system. Although the pathophysiology is not completely understood, pheochromocytomas exert their effects through high levels of catecholamines, mainly epinephrine and norepinephrine, which stimulate adrenergic receptors, including those within the cardiovascular system. Although the most common cardiovascular manifestation is hypertension, patients with pheochromocytoma can present with arrhythmia, hypotension, shock, myocardial ischemia, cardiomyopathy, aortic dissection, and peripheral ischemia. The medical management of the cardiovascular effects of pheochromocytoma is via blockade of adrenergic receptors, usually through the use of alpha blockers, with the addition of beta blockers if needed. However, only surgical resection of the pheochromocytoma is potentially curative, and this tumor requires unique management perioperatively. Because of the variability of presentation and the significant morbidity and mortality of patients with an undiagnosed pheochromocytoma, this entity should not be overlooked in the evaluation of patients with a wide variety of cardiovascular disorders.

Assessment of clinical and radiologic differences between small and large adrenal pheochromocytomas

OBJECTIVE

To evaluate differences in clinical and radiologic features of small and large pheochromocytomas.

MATERIALS AND METHODS

This study included 39 patients with adrenal pheochromocytomas. Several clinical and radiologic features were statistically analyzed and compared between small and large pheochromocytomas.

RESULTS

No significant differences were found in clinical features between them. Small pheochromocytomas had more relatively homogeneous attenuation although large pheochromocytomas had more cystic or necrotic changes.

CONCLUSIONS

Pheochromocytomas tend to have different CT imaging features mimicking other tumors according to the size of the tumors. However, clinical features, CT imaging characteristics, and radioisotope activity are not different between small and large pheochromocytomas.

Management of Adrenal Masses

An adrenal mass can be either symptomatic or asymptomatic in the form of adrenal incidentalomas (AIs) in up to 8 % in autopsy and 4 % in imaging series. Once a diagnosis of adrenal mass is made, we need to differentiate whether it is functioning or nonfunctioning, benign, or malignant. In this article, we provide a literature review of the diagnostic workup including biochemical evaluation and imaging characteristics of the different pathologies. We also discuss the surgical strategies with laparoscopy as the mainstay with partial adrenalectomy in select cases and adrenalectomy in large masses. Follow-up protocol of AIs and adrenocortical carcinoma is also discussed.

Multi-modality imaging of pheochromocytoma

Pheochromocytoma, a rare neuroendocrine adrenal tumor, is often diagnosed by a combination of clinical, laboratory, and radiographic features. While the imaging features of this entity are variable, the use of complementary modalities often helps to target the diagnosis and assess the extent of the disease. We present a multi-modality evaluation of a pheochromocytoma, with CT, MR, MIBG, and pathologic findings, in an individual who initially presented to the Emergency Department with flank pain.

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.

Imaging Features of Various Adrenal Neoplastic Lesions on Radiologic and Nuclear Medicine Imaging

OBJECTIVE

The purpose of this review is to describe the features of diverse adrenal neoplastic lesions on radiologic and nuclear medicine imaging.

CONCLUSION

Various neoplastic lesions with or without malignant potential can occur in the adrenal gland. Knowledge of imaging features of adrenal lesions on radiologic and nuclear medicine imaging will facilitate differential diagnosis and assessment of malignant potential.

Quantitative Versus Qualitative Methods in Evaluation of T2 Signal Intensity to Improve Accuracy in Diagnosis of Pheochromocytoma

OBJECTIVE

The purpose of this study was to assess T2 signal intensity (SI) of adrenal pheochromocytoma at 1.5 T using the rapid acquisitions with relaxation enhancement (RARE) sequence. We also sought to determine whether quantitative parameters can distinguish pheochromocytoma from other adrenal lesions with better accuracy than conventional qualitative methods.

MATERIALS AND METHODS

MRI examinations of 74 patients (26 with pheochromocytoma, 25 with lipid-poor adenomas, 18 with malignant adrenal lesions, and five with adrenal cysts) were retrospectively reviewed. MRI sequences included single-shot fast spin-echo (n = 38) and fast-recovery fast spin-echo (n = 36) acquisitions. T2 SI of lesions was qualitatively compared with CSF. Quantitative evaluation included applying ROI measurements and calculating SI ratio of each mass to liver, spleen, paraspinal muscle, and CSF. Twoway ANOVA compared SI ratios between different adrenal lesions and between two pulse sequences. ROC analysis determined the optimal threshold SI ratio for distinguishing pheochromocytomas from other adrenal lesions.

RESULTS

Sixty-nine percent of pheochromocytomas displayed isointensity to CSF (p < 0.005), resulting in 81% specificity and 69% sensitivity for differentiation of pheochromocytomas from lipid-poor adenomas and malignant lesions. Adrenal-to-muscle SI ratio was the strongest discriminator for differentiation of pheochromocytomas from other lesions. A threshold of at least 3.95 yielded 88% specificity and 81% sensitivity for distinguishing pheochromocytomas from lipid-poor adenomas and malignant adrenal lesions.

CONCLUSION

Quantitative normalization of T2 SI with reference to muscle improves the sensitivity and specificity profile for differentiation of pheochromocytoma compared with qualitative assessment alone. At 1.5 T field strength, an adrenal-to-muscle SI ratio of at least 3.95 is recommended.

Diagnosing phaeochromocytoma/paraganglioma in a patient presenting with critical illness: biochemistry versus imaging

Phaeochromocytomas and paragangliomas (PPGLs) are revealed by acute cardiovascular complications involving end-organ damage in up to 20% of cases, a presentation associated with particularly high risk for mortality. Among such cases, PPGLs should be considered in patients with unexplained left ventricular failure, multi-organ failure, hypertensive crises or shock. The diagnosis of PPGL commonly relies on measurements of metanephrines in plasma or urine. However, acute critical illness is usually associated with sympathoadrenal activation. Thus, levels of metanephrines in patients in an acute emergency or intensive care setting, whether treated or not with vasoactive drugs, usually cannot be used to reliably diagnose PPGL. Delays in provision of diagnostic test results, particularly when these require 24-h urine collections, may also be incompatible for any need for rapid decisions on patient management or therapeutic interventions. The acute emergency situation therefore represents one exception to the rule where imaging studies to search for a PPGL may be undertaken without biochemical evidence of a catecholamine-producing tumour.

Metastatic pheochromocytoma and paraganglioma

BACKGROUND

Metastatic pheochromocytomas (PCs) and paragangliomas (PGLs) are rare neuroendocrine tumours with a strong genetic background.

DESIGN

We searched the PubMed database through February 2015 to identify studies characterizing metastatic PCs/PGLs as well as currently established and evolving therapies.

RESULTS

Large size tumours (> 5 cm), PASS score > 6 and Ki-67 labelling index > 3% are the most robust indices of metastatic PCs/PGLs albeit with great variability. Germline succinate dehydrogenase complex, subunit B (SDHB) mutation constitutes the main reliable molecular predictor of malignancy. Plasma and urinary methoxytyramine are the biochemical markers characterizing metastatic PCs/PGLs along with evolving molecular markers such as miRNAs and SNAIL. Conventional imaging is used for tumour localization, whereas (18)F-FDG-PET for staging of metastatic PCs/PGLs especially those related to SDHB gene mutations. In addition, (68)Ga-DOTATATE PET/CT is emerging as a highly sensitive alternative. Surgery remains the gold standard treatment in reducing tumour bulk and/or controlling the clinical syndrome. Treatment with (131)I-MIBG or radiolabelled somatostatin analogues is considered for unresectable disease. Conventional chemotherapy is reserved for more advanced and refractory to other therapies disease although new schemes are currently evolving. Recent genetic studies have highlighted a number of pathways involved in PCs/PGLs pathogenesis directing towards the use of targeted therapies which have still to be validated in clinical practice.

CONCLUSIONS

Metastatic PCs/PGLs remain an orphan disease that is only curable by surgery. However, advances in genomic analyses have improved the pathogenesis of these tumours and may lead to effective and more personalized treatments 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.

Images of pheochromocytoma in adrenal glands

Pheochromocytomas are relatively rare tumors of the adrenal medulla. A wide spectrum of imaging findings has been described. The aim of this article is to describe the multimodality imaging features of pheochromocytomas including diagnostic pearls that can help differentiate them from other adrenal lesions and pitfalls to avoid.