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, to confirm or exclude adherence of the mass to adjacent structures, and to 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 Transthoracic US is unlikely to offer additional information regarding mediastinal mass characterization beyond that of MRI. Image-Guided Transthoracic Needle Biopsy CT-guided percutaneous needle and core biopsy of accessible mediastinal masses has been shown to be safe and to have a good diagnostic yield, with core biopsy more effective than fine-needle aspiration. Biopsy was more frequently diagnostic for TETs than for lymphoma [101-104]. A retrospective study of 293 consecutive CT-guided mediastinal biopsies performed in 285 patients showed an overall diagnostic yield of 87% for mediastinal masses with a mean size of 5.3 cm and 57% for residual masses at the site of treated lymphoma [101]. Another retrospective study of 52 patients reported a 77% diagnostic yield for needle biopsy of mediastinal masses with a mean size of 6.9 cm [102]. When the distinction of TETs from lymphoma cannot be definitively made by imaging, image-guided Imaging of Mediastinal Masses biopsy has a role. PET/CT guidance for biopsy reportedly yields no diagnostic advantage [104].
Imaging of Mediastinal Masses. 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, to confirm or exclude adherence of the mass to adjacent structures, and to 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 Transthoracic US is unlikely to offer additional information regarding mediastinal mass characterization beyond that of MRI. Image-Guided Transthoracic Needle Biopsy CT-guided percutaneous needle and core biopsy of accessible mediastinal masses has been shown to be safe and to have a good diagnostic yield, with core biopsy more effective than fine-needle aspiration. Biopsy was more frequently diagnostic for TETs than for lymphoma [101-104]. A retrospective study of 293 consecutive CT-guided mediastinal biopsies performed in 285 patients showed an overall diagnostic yield of 87% for mediastinal masses with a mean size of 5.3 cm and 57% for residual masses at the site of treated lymphoma [101]. Another retrospective study of 52 patients reported a 77% diagnostic yield for needle biopsy of mediastinal masses with a mean size of 6.9 cm [102]. When the distinction of TETs from lymphoma cannot be definitively made by imaging, image-guided Imaging of Mediastinal Masses biopsy has a role. PET/CT guidance for biopsy reportedly yields no diagnostic advantage [104].