Chemical-shift MRI versus washout CT for characterizing adrenal incidentalomas

Computed Tomography-Based Machine Learning Differentiates Adrenal Pheochromocytoma From Lipid-Poor Adenoma

OBJECTIVES

To assess the accuracy of computed tomography (CT)-based machine learning models for differentiating subclinical pheochromocytoma (sPHEO) from lipid-poor adenoma (LPA) in patients with adrenal incidentalomas.

PATIENTS AND METHODS

The study included 188 tumors in the 183 patients with LPA and 92 tumors in 86 patients with sPHEO. Pre-enhanced CT imaging features of the tumors were evaluated. Machine learning prediction models and scoring systems for differentiating sPHEO from LPA were built using logistic regression (LR), support vector machine (SVM) and random forest (RF) approaches.

RESULTS

The LR model performed better than other models. The LR model (M1) including three CT features: CT_pre value, shape, and necrosis/cystic changes had an area under the receiver operating characteristic curve (AUC) of 0.917 and an accuracy of 0.864. The LR model (M2) including three CT features: CT_pre value, shape and homogeneity had an AUC of 0.888 and an accuracy of 0.832. The S2 scoring system (sensitivity: 0.859, specificity: 0.824) had comparable diagnostic value to S1 (sensitivity: 0.815; specificity: 0.910).

CONCLUSIONS

Our results indicated the potential of using a non-invasive imaging method such as CT-based machine learning models and scoring systems for predicting histology of adrenal incidentalomas. This approach may assist the diagnosis and personalized care of patients with adrenal tumors.

Draft of the clinical practice guidelines “Adrenal incidentaloma”

The wider application and technical improvement of abdominal imaging procedures in recent years has led to an increasingly frequent detection of adrenal gland masses — adrenal incidentaloma, which have become a common clinical problem and need to be investigated for evidence of hormonal hypersecretion and/or malignancy. Clinical guidelines are the main working tool of a practicing physician. Laconic, structured information about a specific nosology, methods of its diagnosis and treatment, based on the principles of evidence-based medicine, make it possible to give answers to questions in a short time, to achieve maximum efficiency and personalization of treatment. These clinical guidelines include data on the prevalence, etiology, radiological features and assessment of hormonal status of adrenal incidentalomas. In addition, this clinical practice guideline provides information on indications for surgery, postoperative rehabilitation and follow-up.

A Clinical Challenge: Endocrine and Imaging Investigations of Adrenal Masses

Incidentalomas are reported in 3%-4% of patients who undergo abdominal anatomic imaging, making adrenal mass evaluation a common occurrence. An adrenal mass can be caused by a variety of pathologies, such as benign cortical and medullary tumors, malignant tumors (primary or secondary), cysts, hyperplasia, hemorrhage, or more rarely infection/inflammation processes. Functioning tumors usually have increased hormonal production but they are less common. Regardless of their functional status, some tumors have the potential to behave aggressively. Anatomic and functional imaging together with biologic evaluation play a vital role in adrenal pathology subtyping. Most patients are initially evaluated by CT or MRI, which allows for tumor characterization (to a certain extent) and can rule out malignant behavior based on the absence of tumor growth during longitudinal follow-up. In the remaining patients for whom CT or MRI fail to characterize the pathogenesis of adrenal tumors, the use of specialized molecular imaging techniques should be performed after hormonal screening. This review emphasizes well-established and emerging nuclear medicine imaging modalities and describes their use across various clinical scenarios.

Correlation Between Size and Function of Unilateral and Bilateral Adrenocortical Nodules: An Observational Study

OBJECTIVE. Adrenal incidentalomas occur in 5% of adults and can produce autonomous cortisol secretion that increases the risk of metabolic syndrome and cardiovascular disease. The objective of our study was to evaluate the relationship between adrenal nodule size measured on CT and autonomous cortisol secretion. SUBJECTS AND METHODS. In a prospective study of 73 patients 22-87 years old with incidentalomas, unilateral in 52 patients and bilateral in 21 patients, we measured maximum nodule diameter on CT and serum cortisol levels at 8:00 am, 60 minutes after the adrenocorticotropic hormone stimulation test, and after the dexamethasone suppression test. We also studied 34 age-, sex-, and body mass index-matched control subjects. Statistics used were Spearman correlation coefficients, t tests, ANOVA test, and multivariate analysis. RESULTS. The mean maximum diameter of unilateral nodules measured on CT was larger on the right (2.47 ± 0.98 [SD] cm) than on the left (2.04 ± 0.86 cm) (p = 0.01). In the bilateral cases, the mean diameter of the right nodules was 2.69 ± 0.93 cm compared with 2.13 ± 0.89 cm on the left (p = 0.06). Mean baseline serum cortisol level was significantly higher in the patients with incidentalomas (bilateral, 13.1 ± 4.5 mcg/dL [p < 0.001]; unilateral, 9.7 ± 3.2 mcg/dL [p = 0.019]) than in the control subjects (7.5 ± 3.6 mcg/dL). After dexamethasone suppression test, serum cortisol levels were suppressed to less than 1.8 mcg/dL in 100% of control subjects, 33% of patients with bilateral incidentalomas, and 62% of patients with unilateral incidentalomas (p < 0.001). There were significant correlations between maximum nodule diameter on CT and serum cortisol levels after the dexamethasone suppression test (ρ = 0.500; p < 0.001) and at baseline (ρ = 0.373; p = 0.003). CONCLUSION. Increasing size of adrenal nodules is associated with more severe hyper-cortisolism and less dexamethasone suppression; these cases need further evaluation and possibly surgery because of increased risks of metabolic syndrome and cardiovascular mortality.

What the radiologist needs to know: the role of preoperative computed tomography in selection of operative approach for adrenalectomy and review of operative techniques

Adrenalectomy is the standard of care for management of many adrenal tumor types and, in the United States alone, approximately 6000 adrenal surgeries are performed annually. Two general approaches to adrenalectomy have been described; (1) the open approach, in which a diseased adrenal is removed through a large (10-20 cm) abdominal wall incision, and (2) the minimally invasive approach, in which laparoscopy is used to excise the gland through incisions generally no longer than 1-2 cm. Given these disparate technique options, clear preoperative characterization of those specific disease features that inform selection of adrenalectomy approach is critically important to the surgeon. Because most of these features are directly assessed via preoperative abdominal imaging, in particular computed tomography (CT) scanning, a clear mutual understanding among surgeons and radiologists of those adrenal tumor features impacting operative approach selection is vital for planning adrenal surgery. In this context, we review the preoperative CT imaging features that specifically inform adrenalectomy approach selection, provide illustrative examples from our institution's imaging and surgical archives, and provide a stepwise guide to both the open and laparoscopic adrenalectomy approaches.

Isolated Synchronous Adrenal Lesions in Patients with Newly Diagnosed Extra-Adrenal Malignancies

Background:

This study focused on the etiology of patients with extra-adrenal primary malignancy in addition to isolated synchronous adrenal incidentalomas.

Methods:

Patients who were diagnosed as extra-adrenal primary malignancy and synchronous adrenal incidentalomas were enrolled from a single tertiary medical center from 2004 to 2014. Those with a history of malignancy or any extra-adrenal metastases at the time of diagnosis were excluded. Statistical analysis was performed to determine possible predictors for adrenal metastases.

Results:

The primary malignancies of hepatocellular carcinoma and lung cancer had higher rates of adrenal metastases than colon cancer and renal cell carcinoma. Significant predictors for adrenal metastasis were clinical T stage and adrenal mass diameters. Patients with stage T1/2 primary malignancies were more likely to have benign adrenal tumors than those with stage T3 or T4. The average adrenal mass diameters in the benign and metastatic groups were 2.87 and 4.97 cm, respectively (P = 0.001).

Conclusions:

Nearly 40% of the isolated synchronous adrenal incidentalomas in patients with newly diagnosed extra-adrenal malignancies proved to be metastases. In patients with large adrenal lesions, high mass density on computed tomography scans, or a primary malignancy at a high clinical T stage, the risk of adrenal metastasis was high.

A step by step approach in differential diagnosing of adrenal incidentaloma (epinephroma), (with comments on the new Clinical Practice Guidelines of the European Society of Endocrinology)

Objectives. To present a step by step approach for the diagnosis of adrenal incidentaloma (AI).

Method. An extensive review of the literature was conducted, searching the Pub-Med and Google Scholar using the Mesh terms; Adrenal; Incidentaloma; Adrenal tumours; Radiology; Diagnosis. We also did a cross-referencing search of the literature. Comments on the new European guidelines are presented.

Results. The majority of the tumours are non-functioning benign adenomas. The most important radiological characteristic of an adrenal incidentaloma is the radiation attenuation coefficient. Wash out percentage and the imaging characteristics of the tumour may help in diagnosis.

Conclusion. Density less than 10 HU is in most cases characteristic of a lipid rich benign adenoma. More than 10 HU or/and history of malignancy raise the possibility for cancer. 1 mg dexamethasone test and plasma metanephrines should be done in all patients. If there is history of hypokalemia and/or resistant hypertension we test the plasma aldosterone to plasma renin ratio (ARR). Newer studies have shown that tumours even nonfunctioning and less than 4 cm may increase the metabolic risks so we may consider surgery at an earlier stage.