Differentiation between benign and malignant adrenal mass using contrast-enhanced ultrasound
Mireen Friedrich-Rust, Timo Glasemann, Katharina Holzer, Susanne Kiener, Eva Herrmann, Andreas Polta, Stefan Zeuzem & Joerg Bojunga
Background: Adrenal masses can be detected by ultrasound with high sensitivity and specificity. However, a differentiation between benign and malignant adrenal masses is not possible with conventional ultrasound. Contrast-enhanced ultrasound (CEUS) is a established method for the characterization of focal liver lesions. A first pilot study (n=35) analyzing the dynamics of contrast-enhancement during CEUS reported a high sensitivity for differentiation of benign and malignant adrenal mass. The aim of the present study was to evaluate CEUS in a larger patient population using the CEUS patterns identified in the pilot study.
Methods: One hundred and eight patients with 116 adrenal incidentaloma received an ultrasound of the adrenal mass, including Duplex and Doppler ultrasound, followed by CEUS with the contrast agent Sonovue. The dynamic of contrast-enhancement (CE) was analyzed using time-intensity curves. The time of CE in the adrenal mass was used to define four CEUS-patterns: pattern I=early arterial CE, pattern II=arterial CE, pattern III=late CE, pattern IV=no CE. In addition, all patients received CT or MRI and a detailed laboratory testing including hormone profile. In susceptive cases biopsy or adrenalectomy was performed.
Results: CEUS-pattern I&II was seen in all patients with primary or secondary malignant lesions of the adrenal gland (n=16). Sensitivity and specificity of CEUS for the diagnosis of malignant adrenal mass using pattern I&II to define malignancy and pattern III&IV to define benign lesion was 100% (CI (75;100)) and 67% (CI (56;75)), respectively. Eight benign pheochomocytoma, one ganglioneuroma, two myelolipoma and four adenoma showed a perfusion pattern I/II and therefore were misclassified as malignant using CEUS. Overall 38 patients received adrenalectomy of together 40 adrenal masses. In 70% of the surgically removed adrenal masses MRT/CT and CEUS were congruent concerning the characterization of adenoma versus non-adenoma.
Discussion: Contrast-enhanced ultrasound may be a useful method in the diagnostic work-up of adrenal incidentaloma with excellent sensitivity for the diagnosis of malignant adrenal mass.