Mediastinal Masses in Contrast-Enhanced Ultrasound - Retrospective Analysis of 58 Cases

To determine contrast enhancing features of mediastinal masses (ML) using transcutaneous contrast-enhanced ultrasound (CEUS).

Retrospective analysis of n = 58 patients with histologically confirmed ML, which were examined in the period from October 2005 to February 2018 using transcutaneous B-mode ultrasound and CEUS. In n = 29 (50%) histological confirmation was performed by ultrasound guided core-needle biopsy. The lesions were evaluated using CEUS in regard to the enhancement pattern (hyper-, iso-, hypoenhancement, non-enhancement, homogenous, inhomogenous) compared to enhancement of the spleen as an in vivo reference.

N = 53 (91.4%) of ML were malignant (m) (lymphoma n = 36, metastasis n = 11, thymoma n = 2, teratoma n = 1, sarcoma n = 2, seminoma n = 1). In n = 5 (8.6%) cases there was a benign (b) histology (thyroid tissue n = 2, thymus residue n = 1, ganglioneurinoma n = 1, scar tissue: n = 1). In ultrasound, n = 53 (91.4%; (48 = m, 5 = b)) were hypoechoic, n = 5 (8.6%, (5 = m,0 = b)) hyperechoic. In CEUS, n = 35 lesions presented an arterial isoenhancement (60.3%; 33 = m, 2 = b). An arterial hypoenhancement had n = 21 (36.2%, (20 = m,1 = b)), and no enhancement showed n = 2 (3.5%, (0 = m, 2 = b) of the ML. A parenchymal isoenhancement was observed in n = 1 (1.7%, (1 = m, 0 = b)), a hypoenhancement in n = 54 (93.1%; 51 = m, 3 = b) of the patients and almost no enhancement in n = 3 ML (5.2%, (1 = m, 2 = b).) The enhancement was homogeneous in n = 26 (44.8%, (25 = m,1 = b)) cases, in n = 31 (53.5%, (28 = m,3 = b)) inhomogeneous and n = 1 (1.7%) benign lesion was exclusively cystic.

In CEUS, mediastinal tumor formations showed variable arterial enhancement, followed by parenchymal hypoenhancement (wash-out).