DWI MR may be helpful in directing CT-guided biopsy toward sites of higher cellularity and diagnostic yield [110], as may DCE MRI with postprocessed subtraction. MR- guided percutaneous needle biopsy has also been shown to be safe and diagnostically accurate [111]. Radiography Chest After cross-sectional imaging has been performed for mediastinal mass evaluation, there is seldom a role for chest radiography. Variant 4: Indeterminate mediastinal mass on FDG-PET/CT. Next imaging study. CT Chest After FDG-PET/CT has been performed for mediastinal mass evaluation, there is seldom a role for chest CT. Imaging of Mediastinal Masses to CT for surveillance of treated TETs, although if there is insurmountable susceptibility artifact from sternotomy wires using fast spin-echo and other MRI techniques, alternating MRI and CT follow-up can be performed [100]. Cross-sectional imaging by 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 [48-52]. As a supplement to static assessment of tissue plane transgression, dynamic MRI [45-48] during free-breathing or cinematic cardiac gating can be performed to assess movement of the mass relative to adjacent structures, confirm or exclude adherence of the mass to adjacent structures, and observe diaphragmatic motion in real time [80-84]; paradoxical motion or lack of motion can indicate phrenic nerve involvement by the mediastinal mass, without the need to perform a subsequent fluoroscopic sniff test. US Chest There is little relevant literature to support US of an indeterminate mediastinal mass on FDG-PET/CT. 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].
Imaging of Mediastinal Masses. DWI MR may be helpful in directing CT-guided biopsy toward sites of higher cellularity and diagnostic yield [110], as may DCE MRI with postprocessed subtraction. MR- guided percutaneous needle biopsy has also been shown to be safe and diagnostically accurate [111]. Radiography Chest After cross-sectional imaging has been performed for mediastinal mass evaluation, there is seldom a role for chest radiography. Variant 4: Indeterminate mediastinal mass on FDG-PET/CT. Next imaging study. CT Chest After FDG-PET/CT has been performed for mediastinal mass evaluation, there is seldom a role for chest CT. Imaging of Mediastinal Masses to CT for surveillance of treated TETs, although if there is insurmountable susceptibility artifact from sternotomy wires using fast spin-echo and other MRI techniques, alternating MRI and CT follow-up can be performed [100]. Cross-sectional imaging by 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 [48-52]. As a supplement to static assessment of tissue plane transgression, dynamic MRI [45-48] during free-breathing or cinematic cardiac gating can be performed to assess movement of the mass relative to adjacent structures, confirm or exclude adherence of the mass to adjacent structures, and observe diaphragmatic motion in real time [80-84]; paradoxical motion or lack of motion can indicate phrenic nerve involvement by the mediastinal mass, without the need to perform a subsequent fluoroscopic sniff test. US Chest There is little relevant literature to support US of an indeterminate mediastinal mass on FDG-PET/CT. 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].