PET/CT for adrenal assessment. AJR Am J Roentgenol. 2010;195:W91-W95. [PMID: 20651179 DOI: 10.2214/ajr.09.3845]

Adrenal cyst presenting with clinical features of a pheochromocytoma

Benign adrenal cysts are relatively uncommon variants of all adrenal incidentalomas. When identified, most benign adrenal cysts are asymptomatic, which differentiates them from other functional adrenal lesions. There are various types of adrenal cysts, although the most common being an endothelial cyst. Ultimately, evaluation and management approaches are aimed at ruling out a functional adrenal mass and management of symptoms if present. We present a unique presentation of an otherwise healthy male with a large incidental adrenal cyst, later identified as a benign endothelial cyst, who presented with classic symptoms of catecholamine excess. The patient had a negative hormonal evaluation, and his episodic symptoms were resolved with surgical removal of the adrenal mass. This case report and brief review provides valuable insight into the evaluation and management of a unique clinical scenario, where a benign cystic mass led to compression-related symptoms of catecholamine excess that were resolved after removal of the nonfunctional, cystic, mass.

Adrenal schwannoma: why should endocrinologists be aware of this uncommon tumour?

PURPOSE

Adrenal schwannomas (AS) are rare tumours arising from Schwann cells. Due to the high prevalence of adrenal incidentalomas, running into very rare adrenal tumours has become a possibility for high volume expert centres. So far, the clinical behaviour and the radiological characteristics of AS make the pre-operative diagnosis of AS extremely challenging. Due to limited information available, we wanted to summarise the main features of this tumours, in order to raise the profile of an uncommon disease.

METHODS

We performed a MEDLINE and EMBASE research to review the literature. We found 57 case reports and case series and a total of 169 cases, including 2 more cases found in our Institutions. We collected data regarding year of publication, sex, age, and, when available, clinical presentation, hormonal data, radiological features, tumour site and size, treatment, histology and follow-up.

RESULTS

We analysed and discussed the clinical, radiological and pathological characteristics of cases identified, underlying the critical aspects of assessment and management of these tumours which still remain questioned, as, currently, pathologic examination is the only way to make the diagnosis.

CONCLUSIONS

The pre-operative diagnosis of AS is more than challenging and pathologic examination is so far the only way to make a certain diagnosis. Therefore, it is important to consider also the AS in the list of possible diagnoses when faced with a large not secreting adrenal tumour, with suspicious radiological features.

PET-CT and PET-MR in urological cancers other than prostate cancer: An update on state of the art

Hybrid positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (PET/MRI) have enabled the combination of morphologic and functional imaging with the promise of providing better information in guiding therapy. Further advance has been made in the past decade with the development of newer radiotracers and optimization of the technical aspects. We performed a search in PubMed, Scopus, and Google Scholar for peer-reviewed literature concerning the advances and newer developments in the imaging of nonprostate urologic cancers between 2005 and 2017. This review aims at summarizing the current evidence on PET imaging in nonprostate urologic cancers and their impact on the diagnosis, staging, prognostication, response assessment, and restaging of these malignancies. However, much of the evidence is still in infancy and has not been incorporated into routine management or the practice guidelines of National Comprehensive Cancer Network or European Society for Medical Oncology (ESMO).

Differentiation between adrenal adenomas and nonadenomas using dynamic contrast-enhanced computed tomography

This study was performed to evaluate the findings including the time density curve (TD curve), the relative percentage of enhancement washout (Washr) and the absolute percentage of enhancement washout (Washa) at dynamic contrast-enhanced computed tomography (DCE-CT) in 70 patients with 79 adrenal masses (including 44 adenomas and 35 nonadenomas) confirmed histopathologically and/or clinically. The results demonstrated that the TD curves of adrenal masses were classified into 5 types, and the type distribution of the TD curves was significantly different between adenomas and nonadenomas. Types A and C were characteristic of adenomas, whereas types B, D and E were features of nonadenomas. The sensitivity, specificity and accuracy for the diagnosis of adenoma based on the TD curves were 93%, 80% and 87%, respectively. Furthermore, when myelolipomas were excluded, the specificity and accuracy for adenoma were 90% and 92%, respectively. The Washr and the Washa values for the adenomas were higher than those for the nonadenomas. The diagnostic efficiency for adenoma was highest at 7-min delay time at DCE-CT; Washr was more efficient than Washa. Washr ≥34% and Washa ≥43% were both suggestive of adenomas and, on the contrary, suspicious of nonadenomas. The sensitivity, specificity and accuracy for the diagnosis of adenoma were 84%, 77% and 81%, respectively. When myelolipomas were precluded, the diagnostic specificity and accuracy were 87% and 85%, respectively. Therefore, DCE-CT aids in characterization of adrenal tumors, especially for lipid-poor adenomas which can be correctly categorized on the basis of TD curve combined with the percentage of enhancement washout.

Adrenal imaging (Part 1): Imaging techniques and primary cortical lesions

Adrenal glands can be affected by a variety of lesions. Adrenal lesions can either be primary, of adrenal origin, or secondary to other pathologies. Primary adrenal lesions can further be either of cortical or medullary origin. Functioning adrenal lesions can also give clues to the histologic diagnosis and direct workup. Over the years, various imaging techniques have been developed that have increased diagnostic accuracy and helped in better characterization of adrenal lesions non-invasively. In the first part of the two part series, we review adrenal imaging techniques and adrenal cortical tumors such as adenomas, adrenocortical tumors, adrenal hyperplasia and oncocytomas.

What parameters from 18F-FDG PET/CT are useful in evaluation of adrenal lesions?

PURPOSE

Prior studies have suggested that (18)F-FDG PET/CT can help characterize adrenal lesions and differentiate adrenal metastases from benign lesions. The aim of this study was to assess the value of (18)F-FDG PET/CT for the differentiation of malignant from benign adrenal lesions.

METHODS

This retrospective study included 85 patients (47 men and 38 women, age 63.8 ± 10.8 years) who had undergone (18)F-FDG PET/CT (60 min after injection 300 - 370 MBq (18)F-FDG; Biograph 64 scanner) for evaluation of 102 nonsecreting adrenal masses. For semiquantitative analysis, the maximum standardized uptake value (SUVmax), adrenal to liver (T/L) SUVmax ratio, mean CT attenuation value and tumour diameter were measured in all lesions and compared with the pathological findings.

RESULTS

Malignant adrenal tumours (68% of evaluated tumours) had a significantly higher mean SUVmax (13.0 ± 7.1 vs. 3.7 ± 3.0), a higher T/L SUVmax ratio (4.2 ± 2.6 vs. 1.0 ± 0.9), a higher CT attenuation value (31.9 ± 16. 7 HU vs. 0.2 ± 25.8 HU) and a greater diameter (43.6 ± 23.7 mm vs. 25.6 ± 13.3 mm) than benign lesions. The false-positive findings were tuberculosis and benign phaeochromocytoma. Based on ROC analysis, a T/L SUVmax ratio >1.53, an adrenal SUVmax >5.2, an attenuation value >24 HU and a tumour diameter >30 mm were chosen as the optimal cut-off values for differentiating malignant from benign tumours. The areas under the ROC curves for the selected cut-off values were 0.96, 0.96, 0.88 and 0.77, respectively. A multivariate logistic regression model revealed that the T/L SUVmax ratio was an independent prognostic factor for malignancy (p < 0.001); a CT attenuation value of >25 HU and a tumour diameter >30 mm had no additional individual importance in the diagnosis of malignancy.

CONCLUSION

Using a T/L SUVmax ratio >1.53 and an adrenal SUVmax >5.2 in (18)F-FDG PET/CT led to high diagnostic sensitivity, specificity and negative predictive value for characterizing adrenal tumours. The diagnostic accuracies of the two parameters were comparable, but T/L SUVmax ratio was an independent predictor of malignancy.

Cross-sectional imaging work-up of adrenal masses

Advances in medical imaging with current cross-section modalities enable non-invasive characterization of adrenal lesions. Computed tomography (CT) provides characterization with its non-contrast and wash-out features. Magnetic resonance imaging (MRI) is helpful in further characterization using chemical shift imaging (CSI) and MR spectroscopy. For differentiating between benign and malignant masses, positron emission tomography (PET) imaging is useful with its qualitative analysis, as well as its ability to detect the presence of extra-adrenal metastases in cancer patients. The work-up for an indeterminate adrenal mass includes evaluation with a non-contrast CT. If a lesion is less than 10 Hounsfield Units on a non-contrast CT, it is a benign lipid-rich adenoma and no further work-up is required. For the indeterminate adrenal masses, a lipid-poor adenoma can be differentiated from a metastasis utilizing CT wash-out features. Also, MRI is beneficial with CSI and MR spectroscopy. If a mass remains indeterminate, PET imaging may be of use, in which benign lesions demonstrate low or no fluorodeoxyglucose activity. In the few cases in which adrenal lesions remain indeterminate, surgical sampling such as percutaneous biopsy can be performed.

[Diagnosis and management of adrenal incidentaloma]

The growing demand for imaging tests and the progressive aging of the population have led to a progressive increase in the detection of indeterminate adrenal lesions. Once an adrenal incidentaloma is detected, clinical and hormone tests together with a battery of imaging techniques (CT, MRI, PET/CT…) make it possible to determine the cause in most cases. In this article, we discuss the advantages and limitations of each technique. We show the imaging characteristics of the most common adrenal lesions and propose a diagnostic algorithm to enable their diagnosis.