Primary hyperaldosteronism (Conn syndrome): MR imaging findings

Screening and diagnosis of primary aldosteronism. Consensus document of all the Spanish Societies involved in the management of primary aldosteronism

Primary aldosteronism (PA) is the most frequent cause of secondary hypertension (HT), and is associated with a higher cardiometabolic risk than essential HT. However, PA remains underdiagnosed, probably due to several difficulties clinicians usually find in performing its diagnosis and subtype classification. The aim of this consensus is to provide practical recommendations focused on the prevalence and the diagnosis of PA and the clinical implications of aldosterone excess, from a multidisciplinary perspective, in a nominal group consensus approach by experts from the Spanish Society of Endocrinology and Nutrition (SEEN), Spanish Society of Cardiology (SEC), Spanish Society of Nephrology (SEN), Spanish Society of Internal Medicine (SEMI), Spanish Radiology Society (SERAM), Spanish Society of Vascular and Interventional Radiology (SERVEI), Spanish Society of Laboratory Medicine (SEQC(ML)), Spanish Society of Anatomic-Pathology, Spanish Association of Surgeons (AEC).

Predicting Bilateral Subtypes of Primary Aldosteronism Without Adrenal Vein Sampling: A Systematic Review and Meta-analysis

CONTEXT

Primary aldosteronism (PA) is the most common endocrine cause of hypertension. The final diagnostic step involves subtyping, using adrenal vein sampling (AVS), to determine if PA is unilateral or bilateral. The complete PA diagnostic process is time and resource intensive, which can impact rates of diagnosis and treatment. Previous studies have developed tools to predict bilateral PA before AVS.

OBJECTIVE

Evaluate the sensitivity and specificity of published tools that aim to identify bilateral subtypes of PA.

METHODS

Medline and Embase databases were searched to identify published models that sought to subtype PA, and algorithms to predict bilateral PA are reported. Meta-analysis and meta-regression were then performed.

RESULTS

There were 35 studies included, evaluating 55 unique algorithms to predict bilateral PA. The algorithms were grouped into 6 categories: those combining biochemical, radiological, and demographic characteristics (A); confirmatory testing alone or combined with biochemical, radiological, and demographic characteristics (B); biochemistry results alone (C); adrenocorticotropic hormone stimulation testing (D); anatomical imaging (E); and functional imaging (F). Across the identified algorithms, sensitivity and specificity ranged from 5% to 100% and 36% to 100%, respectively. Meta-analysis of 30 unique predictive tools from 32 studies showed that the group A algorithms had the highest specificity for predicting bilateral PA, while group F had the highest sensitivity.

CONCLUSIONS

Despite the variability in published predictive algorithms, they are likely important for decision-making regarding the value of AVS. Prospective validation may enable medical treatment upfront for people with a high likelihood of bilateral PA without the need for an invasive and resource-intensive test.

Open adrenalectomy: A 20-year review of our experience in a developing country

Introduction

The aim of this study was to present our 20-year experience regarding open adrenalectomy (OA) during laparoscopic era in a developing country Turkey.

Materials and Methods

A retrospective and descriptive study of patients with adrenal mass undergoing OA in the surgery department of our hospital, between January 1993 and January 2013, was carried out. All operations were performed by two surgeons.

Results

Ninety patients who underwent OA in our clinic were reviewed retrospectively. The mean number of adrenal operations per month during this period was 0.38 ± 0.12. The patient included 35 men (38.8%) and 55 women (61.2%), with a mean age of 46.4 ± 17 years. The mean body mass index was 28.4 ± 5.25, and the mean American Society of Anesthesiologists score was 2.6 ± 0.57. The mean operative time was 88 ± 27 min. The mean maximum diameter of all the lesions was 4.8 ± 1.3 cm (range: 1.2-21 cm). The mean blood loss was 118 ± 23 ml during the operations. Postoperative complications were observed in four patients (5.5%). There was no mortality. The length of hospital stay was 6.2 ± 2.1 days. The most frequent type of the histological type was benign adenoma (48.8%).

Conclusion

OA in a developing country is a safe method as an alternative for laparoscopic adrenalectomy which has a difficult learning curve.

Adrenal Imaging in Patients with Endocrine Hypertension

Hypertension is one of the commonest chronic diseases contributing to cardiovascular disease. Idiopathic (primary) hypertension accounts for approximately 85% of the diagnosed cases, and 15% of hypertensive patients have other contributing conditions leading to elevated blood pressure (secondary hypertension). Endocrine hypertension is a common secondary cause of hypertension. The most common causes of endocrine hypertension are excess production of mineralocorticoids (ie, primary hyperaldosteronism), glucocorticoids (Cushing syndrome), and catecholamines (pheochromocytoma). After biochemical confirmation of hormonal excess, appropriate use of imaging modalities, both functional and anatomic, should occur for the diagnostic workup of these patients and for location of the source of hormonal excess.

Multimodality Imaging in Patients with Secondary Hypertension: With a Focus on Appropriate Imaging Approaches Depending on the Etiologies

Although the causes of hypertension are usually unknown, about 10% of the cases occur secondary to specific etiologies, which are often treatable. Common categories of secondary hypertension include renal parenchymal disease, renovascular stenosis, vascular and endocrinologic disorders. For diseases involving the renal parenchyma and adrenal glands, ultrasonography (US), computed tomography (CT) or magnetic resonance (MR) imaging is recommended. For renovascular stenosis and vascular disorders, Doppler US, conventional or noninvasive (CT or MR) angiography is an appropriate modality. Nuclear imaging can be useful in the differential diagnosis of endocrine causes. Radiologists should understand the role of each imaging modality and its typical findings in various causes of secondary hypertension. This article focuses on appropriate imaging approaches in accordance with the categorized etiologies leading to hypertension.

Adrenal Imaging

Cross-sectional imaging can make a specific diagnosis in lesions, such as myelolipomas, cysts, and hemorrhage, and is often sufficient to distinguish benign from malignant adrenal processes. CT and MRI are useful studies to identify pheochromocytomas and cortisol-secreting or androgen-secreting tumors. In patients with primary aldosteronism, adrenal venous sampling remains the most accurate localizing study and should be performed in all patients older than 35. Radiolabeled isotope studies serve as second-line diagnostic tests for malignant adrenal tumors, primary or metastatic, as well as for pheochromocytoma. Nuclear imaging studies should follow a robust hormonal diagnosis and be correlated with findings on cross-sectional imaging.

Novel contributions of multimodality imaging in hypertension: A narrative review

Hypertension is currently one of the most prevalent illnesses worldwide, and is the second most common cause of heart failure, only behind ischemic cardiomyopathy. The development of novel multimodality imaging techniques in recent years has broadened the diagnostic methods, risk stratification and monitoring of treatment of cardiovascular diseases available for clinicians. Cardiovascular magnetic resonance (CMR) has a great capacity to evaluate cardiac dimensions and ventricular function, is extremely useful in ruling-out ischemic cardiomyopathy, the evaluation of the vascular system, in making the differential diagnosis for resistant hypertension and risk stratification for hypertensive cardiomyopathy and constitutes today, the method of choice to evaluate left ventricular systolic function. Computed tomography (CT) is the method of choice for the evaluation of vascular anatomy, including coronary arteries, and is also able to provide both functional and structural information. Finally, nuclear cardiology studies have been traditionally used to evaluate myocardial ischemia, along with offering the capacity to evaluate ventricular, endothelial and cardiac innervation function; information that is key in directing the treatment of the patient. In this narrative review, the most recent contributions of multimodality imaging to the patient with hypertension (CMR, CT and nuclear cardiology) will be reviewed.

Cardiovascular magnetic resonance in systemic hypertension

Systemic hypertension is a highly prevalent potentially modifiable cardiovascular risk factor. Imaging plays an important role in the diagnosis of underlying causes for hypertension, in assessing cardiovascular complications of hypertension, and in understanding the pathophysiology of the disease process. Cardiovascular magnetic resonance (CMR) provides accurate and reproducible measures of ventricular volumes, mass, function and haemodynamics as well as uniquely allowing tissue characterization of diffuse and focal fibrosis. In addition, CMR is well suited for exclusion of common secondary causes for hypertension. We review the current and emerging clinical and research applications of CMR in hypertension.

Role of radiology in the management of primary aldosteronism

The diagnosis of primary aldosteronism, the most common form of secondary hypertension, is based on clinical and biochemical features. Although radiology plays no role in the initial diagnosis, it has an important role in differentiating between the two main causes of primary aldosteronism: aldosterone-producing adenoma (APA) and bilateral adrenal hyperplasia (BAH). This distinction is important because APAs are generally managed surgically and BAH medically. Adrenal venous sampling is considered the standard of reference for determining the cause of primary aldosteronism but is technically demanding, operator dependent, costly, and time consuming, with a low but significant complication rate. Other imaging modalities, including computed tomography, magnetic resonance imaging, and adrenal scintigraphy, have also been used to determine the cause of primary aldosteronism. Cross-sectional imaging has traditionally focused on establishing the diagnosis of an APA, with that of BAH being one of exclusion. A high specificity for detecting an APA is desirable, since it will avert unnecessary surgery in patients with BAH. However, an overreliance on cross-sectional imaging can lead to the incorrect treatment of affected patients, mainly due to the wide variation in the reported diagnostic performance of these modalities. A combination of modalities is usually required to confidently determine the cause of primary aldosteronism. The quest for optimal radiologic management of primary aldosteronism continues just over a half century since this disease entity was first described.

Imaging functional adrenal disorders

Technological developments in cross-sectional imaging have revolutionized the localization and characterization of functioning adrenal pathology. With effective use of modern imaging, the diagnosis of the cause and nature of functioning adrenal pathology can be reached speedily, accurately and efficiently in the majority of patients. We review the appearance of primary and secondary adrenal pathology, evaluate the diagnostic performance of imaging modalities, highlight newer technical developments, and propose a rational use of these tests in identifying functioning adrenal disease.

Magnetic Resonance Imaging of the Adrenal Glands

Differentiation of pathologic alterations of the adrenal glands is still a frequent and challenging problem of daily practice in radiology. Two main groups of patients have to be differentiated: those with clinical symptoms, mainly of endocrinopathies, and those in which a mass of the adrenal gland is detected incidentally. In the first group, magnetic resonance imaging (MRI) plays a minor role, although it allows to detect and often even differentiate the cause of the disease. In the second group, MRI has an excellent performance in differentiating between adenomas and non-adenomatous lesions of the adrenal glands.

MR imaging of the adrenal glands

MR imaging is used commonly for imaging the adrenal glands. Its high-contrast resolution and multiplanar imaging capability enables the detection and characterization of many adrenal masses. The advent of chemical-shift imaging revolutionized the role of MR imaging in characterizing adrenal masses. In this article, the authors discuss the range of MR appearances of common and uncommon adrenal masses, focusing on the nonfunctioning incidentally discovered mass and its characterization methods. MR imaging is continuously improving. The increasing use of higher strength magnets and the introduction of newer coils, sequences, and techniques will help detect and characterize very small adrenal masses, quantify their fat content, and provide exquisite morphologic images of the gland and its vascular supply.

Diagnostic performance of CT versus MR in detecting aldosterone-producing adenoma in primary hyperaldosteronism (Conn's syndrome)

The aim of the present study is to compare the diagnostic performance of CT and MR imaging in detecting aldosterone-producing adenoma and to compare the interobserver variability in the detection of an aldosterone-producing adenoma on CT and MR. A retrospective study of 34 patients with primary hyperaldosteronism was performed. A total of 17 cases of aldosterone-producing adenoma and 17 cases of bilateral adrenal hyperplasia were included. The final diagnosis of an adenoma was made by surgery with histological confirmation, whereas that of bilateral adrenal hyperplasia was made on adrenal venous sampling or a good biochemical and clinical response following medical treatment alone and in the absence of a unilateral radiological abnormality. The CT (n=30) and MR (n=24) scans were reviewed independently by two radiologists experienced in adrenal imaging, who were unaware of the cause of the primary hyperaldosteronism. The diagnostic performances of both observers in detecting an aldosterone-producing adenoma on CT and MR imaging were compared. The 16 adenomatous nodules that were detected on imaging ranged from 1 to 4.75 cm in diameter. The calculated sensitivity and specificity for detecting aldosterone-producing adenoma were 87 and 93% for one observer and 85 and 82% for the other observer on CT, and 83 and 83% for one observer and 92 and 92% for the other observer on MR, respectively. Receptor operating characteristics curve analysis showed similar performances of both observers in detecting an aldosterone-producing adenoma on CT and MR imaging. There was good interobserver agreement on CT (k=0.71) and on MR (k=0.67). We have demonstrated comparable diagnostic performance and good interobserver agreement on CT and MR imaging for the detection of aldosterone-producing adenoma.

CT of primary hyperaldosteronism (Conn's syndrome): the value of measuring the adrenal gland

OBJECTIVE

The objectives of our study of patients with primary hyperaldosteronism (Conn's syndrome) were to determine whether the adrenal glands are larger in patients with bilateral adrenal hyperplasia than in those with aldosterone-producing adenomas or in healthy control subjects; and whether a CT criterion based on adrenal gland size can be developed to positively diagnose bilateral adrenal hyperplasia.

MATERIALS AND METHODS

A retrospective study of CT scans of 28 patients with primary hyperaldosteronism was performed. The means of two observers' measurements of adrenal gland size were recorded and compared with published normal values. In addition, a radiologist experienced in adrenal imaging and unaware of the cause of the primary hyperaldosteronism diagnosed either bilateral adrenal hyperplasia or aldosterone-producing adenoma by visual inspection.

RESULTS

The adrenal glands in patients with bilateral adrenal hyperplasia were significantly (p < 0.05) larger than those in patients with aldosterone-producing adenoma or in healthy control subjects. A sensitivity of 100% was achieved when a mean limb width of greater than 3 mm was used to diagnose bilateral adrenal hyperplasia, and a specificity of 100% was achieved when the mean limb width was 5 mm or greater. Receiver operating characteristic curve analysis showed that the overall performance of the radiologist and the mean adrenal limb width in detecting bilateral adrenal hyperplasia were equivalent.

CONCLUSION

In patients with primary hyperaldosteronism, adrenal limb measurements on CT can aid in differentiating bilateral adrenal hyperplasia from aldosterone-producing adenoma because the adrenal glands in bilateral adrenal hyperplasia are larger.

Diagnosis and management of primary aldosteronism

Identifying primary aldosteronism within the hypertensive population is an important clinical challenge, as most patients with a unilateral source of excess aldosterone secretion are amenable to surgical cure. At least 20% of patients with primary aldosteronism have normal serum potassium levels. Therefore, screening tests should not be based on recognition of hypokalemia alone. Rather, the diagnosis should depend on identifying renin suppression and measuring the ratio of plasma aldosterone concentration to plasma renin activity. The diagnosis may be confirmed by performing an aldosterone suppression test after oral salt loading. Once primary aldosteronism has been established, it is necessary to exclude glucocorticoid-remediable aldosteronism and then proceed to localization studies. Detecting a unilateral source of aldosterone, usually due to an adenoma (Conn syndrome), is achieved by postural hormonal testing and confirmed by selective venous sampling (SVS) with measurement of aldosterone concentrations (expressed as the aldosterone/cortisol ratio) in each adrenal vein. SVS is enjoying a revival in many institutions as it is more sensitive and specific than either cross-sectional imaging or scintigraphy and has the potential to influence significantly both the diagnosis and clinical decision-making. Patients with unilateral disease are ideally treated by laparoscopic adrenalectomy. Patients in whom localization is not achieved usually have bilateral adrenal hyperplasia and are treated medically.

Aldosteronoma

Aldosteronoma is a surgically curable cause of hypertension. Recent studies have found aldosteronomas to be a more common cause of hypertension than previously thought. At least 2% of patients with hypertension may have an aldosteronoma. More than 50% of these patients are normokalemic because of earlier diagnosis or milder disease, but still benefit from adrenalectomy. Patients with hypertension should be screened for possible primary hyperaldosteronism regardless of their serum potassium level. When used in conjunction with the appropriate laboratory tests, high-resolution computerized tomography scanning helps the surgeon to differentiate accurately between an adrenal adenoma and bilateral adrenal hyperplasia. Focused approach and laparoscopic resection are the norm for the surgical treatment of aldosteronoma.

Imaging of adrenal masses

Adrenal pathology may be discussed based on hormonal functionality of the adrenals, appearances on imaging modality, or pathological determination. There are three main categories of adrenal function. Hyperfunctional states include Conn's or Cushing's syndrome. Lesions with normal function may be detected incidentally. Hypofunctional states may occur from idiopathic Addison's disease or some bilateral adrenal pathology. The most common modalities for characterization of adrenal pathology are non-enhanced CT, often followed by contrast CT or chemical shift MRI. The common appearance on non-enhanced CT is a well-defined homogeneous lesion with low-density due to the microscopic fat present and adrenal adenomas. When density criteria are not met, many of these may be characterized as adenomas by washed out of contrast or signal decrease using in phase and out-of-phase MRI sequences. Other non-invasive modalities may incidentally discover adrenal lesions, but are not typically used in the work-up. NP-59 is an uncommonly used nuclear medicine technique which is very specific for adenoma when correlated with pathology on other imaging studies. In the rare cases where non-invasive imaging is non-specific, fine needle aspiration or core biopsies may be necessary. However, biopsies have associated risks including infection and hemorrhage. The imaging appearance of an adrenal lesion is often specific such that further imaging is not necessary. These lesions include adrenal adenoma, pheochromocytoma, myelolipoma, adrenal cyst, and some large adrenocortical carcinomas. However, the findings in lesions such as metastasis, smaller primary adrenal carcinomas, lymphoma, granulomatous disease, and many adenomas are not as specific. In the proper clinical situation, follow-up imaging may be necessary, or biopsy may be warranted.

Concurrent secretion of aldosterone and cortisol from an adrenal adenoma - value of MRI in diagnosis

A 43-year-old female with a 24-years history of hypertension presented for further investigation and management of primary hyperaldosternoism. Postural studies were not conclusive and magnetic resonance (MR) imaging demonstrated a 27 x 18 mm lesion of the right adrenal gland which showed no signal loss during in and out of phase imaging. Although these appearances were considered to be atypical of those seen on MR in patients with aldosterone producing adrenal adenomas the patient underwent an adrenalectomy with removal of a 3 x 3 x 2 cm right adrenal mass. Post-operatively she became hypotensive and a 0900 hours serum cortisol was undetectable (< 50 nmol/l), consistent with adrenal insufficiency. Following the administration of hydrocortisone there was normalization of the blood pressure and subsequent adrenal stimulation tests confirmed the presence of functioning adrenal tissue albeit with an inadequate response. Cortisol measurement from preoperative samples revealed loss of normal diurnal rhythm whereas DHEAS levels both pre and postoperatively were undetectable, consistent with ACTH supression resulting from autonomous cortisol secretion in addition to aldosterone. Concurrent secretion of cortisol should always be considered in Conn's adenomas particularly when atypical radiological features are present.