Radiography Chest When there is a clinically suspected mediastinal mass, it is reasonable to perform a chest radiograph as an initial imaging step. Chest radiography can help localize a mass to a specific mediastinal compartment and thereby narrow the differential diagnosis [85-88]. It can also show any associated pleural, lung, and bone findings to some extent. Chest radiography offers limited assistance regarding tissue characterization of mediastinal masses, with the exception of its occasional demonstration of calcium within a lesion. US Chest There is little relevant literature to support the use of ultrasound (US) in the initial evaluation of a clinically suspected mediastinal mass. Because of the limited transthoracic sonographic window, US would not be useful to screen for a clinically suspected mediastinal mass. Transthoracic US can be used to evaluate mediastinal masses, when accessible to the sonographic window, delineating their size, location, cystic versus solid nature, relationship to important vascular structures, and vascularity, with some diagnostic potential [89]. Endoscopic US can similarly evaluate mediastinal masses when encompassed in the sonographic window [90]. The tissue characterization capability of US is inferior to MRI but not to CT. Image-Guided Transthoracic Needle Biopsy Image-guided transthoracic needle biopsy is not a form of initial imaging. Variant 2: Indeterminate mediastinal mass on radiography. Next imaging study. CT Chest Cross-sectional imaging, by its very nature, 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, thus permitting noninvasive diagnosis of many mature teratomas [40]. Pre- and postcontrast Imaging of Mediastinal Masses
Imaging of Mediastinal Masses. Radiography Chest When there is a clinically suspected mediastinal mass, it is reasonable to perform a chest radiograph as an initial imaging step. Chest radiography can help localize a mass to a specific mediastinal compartment and thereby narrow the differential diagnosis [85-88]. It can also show any associated pleural, lung, and bone findings to some extent. Chest radiography offers limited assistance regarding tissue characterization of mediastinal masses, with the exception of its occasional demonstration of calcium within a lesion. US Chest There is little relevant literature to support the use of ultrasound (US) in the initial evaluation of a clinically suspected mediastinal mass. Because of the limited transthoracic sonographic window, US would not be useful to screen for a clinically suspected mediastinal mass. Transthoracic US can be used to evaluate mediastinal masses, when accessible to the sonographic window, delineating their size, location, cystic versus solid nature, relationship to important vascular structures, and vascularity, with some diagnostic potential [89]. Endoscopic US can similarly evaluate mediastinal masses when encompassed in the sonographic window [90]. The tissue characterization capability of US is inferior to MRI but not to CT. Image-Guided Transthoracic Needle Biopsy Image-guided transthoracic needle biopsy is not a form of initial imaging. Variant 2: Indeterminate mediastinal mass on radiography. Next imaging study. CT Chest Cross-sectional imaging, by its very nature, 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, thus permitting noninvasive diagnosis of many mature teratomas [40]. Pre- and postcontrast Imaging of Mediastinal Masses