CT Chest Cross-sectional imaging can more definitively localize a lesion to a mediastinal compartment than chest radiography. Further tissue characterization of mediastinal masses beyond chest radiography is achievable by CT which can demonstrate and distinguish not only calcium and macroscopic fat but also water attenuation fluid, permitting noninvasive diagnosis of many mature teratomas [40]. Pre- and postcontrast conventional CT or dual- energy CT can show enhancing cellular components of lesions [41,42]; however, the soft-tissue contrast of CT is sometimes insufficient. For example, benign hyperattenuating thymic cysts on CT can be misinterpreted as thymomas, leading to unnecessary thymectomy [24]. Not infrequently, a mediastinal lesion is indeterminate by CT and requires further workup. CT is superior to chest radiography for detection of invasion of the mass across tissue planes, secondary to its higher contrast resolution. Invasion of adjacent large blood vessels and the chest wall is important to identify, as it is associated with a higher probability of incomplete surgical resection of primary malignant mediastinal masses [43]. In addition, it can direct surgery when still planned and, in other cases, direct toward other forms of clinical management, including neoadjuvant chemotherapy and radiation therapy. As a supplement to static assessment of tissue plane transgression, which can be difficult, dynamic CT [44] during free-breathing or cinematic cardiac gating can be performed to assess movement of the mass relative to adjacent structures and confirm or exclude adherence of the mass to adjacent structures; however, dynamic MRI during free-breathing can accomplish the same task [45- 48]. MRI remains superior to CT for detection of invasion of the mass across tissue planes, including the chest wall and diaphragm, and involvement of neurovascular structures, secondary to its higher soft-tissue contrast [49-52].
Imaging of Mediastinal Masses. CT Chest Cross-sectional imaging can more definitively localize a lesion to a mediastinal compartment than chest radiography. Further tissue characterization of mediastinal masses beyond chest radiography is achievable by CT which can demonstrate and distinguish not only calcium and macroscopic fat but also water attenuation fluid, permitting noninvasive diagnosis of many mature teratomas [40]. Pre- and postcontrast conventional CT or dual- energy CT can show enhancing cellular components of lesions [41,42]; however, the soft-tissue contrast of CT is sometimes insufficient. For example, benign hyperattenuating thymic cysts on CT can be misinterpreted as thymomas, leading to unnecessary thymectomy [24]. Not infrequently, a mediastinal lesion is indeterminate by CT and requires further workup. CT is superior to chest radiography for detection of invasion of the mass across tissue planes, secondary to its higher contrast resolution. Invasion of adjacent large blood vessels and the chest wall is important to identify, as it is associated with a higher probability of incomplete surgical resection of primary malignant mediastinal masses [43]. In addition, it can direct surgery when still planned and, in other cases, direct toward other forms of clinical management, including neoadjuvant chemotherapy and radiation therapy. As a supplement to static assessment of tissue plane transgression, which can be difficult, dynamic CT [44] during free-breathing or cinematic cardiac gating can be performed to assess movement of the mass relative to adjacent structures and confirm or exclude adherence of the mass to adjacent structures; however, dynamic MRI during free-breathing can accomplish the same task [45- 48]. MRI remains superior to CT for detection of invasion of the mass across tissue planes, including the chest wall and diaphragm, and involvement of neurovascular structures, secondary to its higher soft-tissue contrast [49-52].