Utilisation of combined¹⁸F-FDG PET/CT scan for differential diagnosis between benign and malignant adrenal enlargement

Abstract

Objective: To assess the properties of adrenal lesions with and without known primary cancer and investigate predictors for differential diagnosis between benign and malignant adrenal enlargement. Methods: This retrospective study used fluorine-18 fludeoxyglucose positron emission tomography (PET)/CT in 325 patients with adrenal lesions (229 with known primary cancer and 96 without primary cancer). Age, sex, the presence of right and left masses, nodules or hyperplasia, unenhanced attenuation, maximum standardised uptake value (SUV max ) ratio, and the presence of metastasis in other body parts and locations of the primary cancer were assessed. Univariate and multivariate analyses were used to assess variables associated with risk of adrenal metastasis. Results: Patients with adrenal metastasis vs those without had a higher frequency of primary lung cancer (52.3% vs 30.7%) but a lower frequency of gastrointestinal cancer (7.9% vs 16.6%). The frequency of other abnormalities, including adenoma and hyperplasia, was similar between patients with and without known primary cancer. A higher proportion of patients with adrenal metastasis regardless of primary cancer site were younger, had a nodule or a mass, had an unenhanced attenuation of .10 HU, had an SUV max ratio of .2.5, and had metastasis in other body parts. Analysis found independent associations of age, unenhanced attenuation of .10 HU, SUV max ratio of .2.5 and the presence of metastasis in other body parts with adrenal metastasis. The combination of the four variables was strongly associated with adrenal metastasis. Conclusion: PET/CT was useful in characterising adrenal lesions as benign or malignant and helpful in identifying adrenal metastasis and cancer severity. Advances in knowledge: PET/CT can help in the differential diagnosis between benign and malignant adrenal enlargement.The adrenal gland is a common site of metastasis in patients with cancer. Up to 50% of adrenal lesions in patients with known primary non-adrenal cancers are malignant disease [1-4]. The most common malignant lesions that metastasise to the adrenal gland include lung, liver, colon, lymphoma, melanoma, breast, kidney, oesophagus, pancreas and stomach cancer [4][5][6]. However, diagnosis of an adrenal lesion as malignant or benign can be problematic. Characterisation of these adrenal lesions is therefore critical to stage the primary disease, direct therapy and predict prognosis. Although CT and MRI are typically used to characterise a lesion, a small but important number of adrenal lesions are found to be indeterminate on crosssectional images [7][8][9].Several reports have documented the effectiveness of standalone fluorine-18 fludeoxyglucose ( 18 F-FDG) positron emission tomography (PET) to differentiate benign from malignant adrenal lesions [8][9][10]. Interest has focused on the ability of integrated in-line PET/CT to definitively characterise these lesions given that this technique combines the anatomical and densitometrical applications of CT and the functional and metabol...

High False Positivity in Positron Emission Tomography is a Potential Diagnostic Pitfall in Patients with Suspected Adrenal Metastasis

“…From our analysis, patients with primary lung malignancy had almost 11 times greater chance of harboring an adrenal metastasis than those with non-lung primary malignancy. This is consistent with the finding that lung primary malignancy is the most common malignancy metastasizing to the adrenals [1][2][3][10][11] . Using an optimal cut-off of 2.65, those with SUVmax >2.65 had a 31.6 times greater chance of adrenal metastasis than those with SUVmax ≤2.65.…”

Increased 18F-FDG signal recovery from small physiological structures in digital PET/CT and application to the pituitary gland

“…In this study, we have showed that the improvement of signal measurement in dPET leads to an improved physiological uptake in PG. Of course, physiological uptake of other small normal structures (as adrenal glands, ganglia), will be impacted similarly 19,20 .…”

Left Adrenal Biopsy Using the Convex Curvilinear Ultrasound Scope

“…The left adrenal gland is the more common site of adrenal metastasis [15,17] and is almost always accessible from the stomach [18,19,20]. Several studies have looked at the use of esophageal ultrasound-guided FNA for the diagnosis of left adrenal lesions [18,19,20].…”