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 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 biopsy has a role. PET/CT guidance for biopsy reportedly yields no diagnostic advantage [104]. When the lesion is visible within the sonographic window, transthoracic US-guided biopsy of mediastinal masses is also feasible, with color Doppler and contrast-enhanced sonographic techniques providing additional value [105-108], and with core biopsy more effective than fine-needle aspiration. Endoscopic biopsy of mediastinal masses is also feasible and effective, although not in the purview of this topic [109]. 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.
Imaging of Mediastinal Masses. 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 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 biopsy has a role. PET/CT guidance for biopsy reportedly yields no diagnostic advantage [104]. When the lesion is visible within the sonographic window, transthoracic US-guided biopsy of mediastinal masses is also feasible, with color Doppler and contrast-enhanced sonographic techniques providing additional value [105-108], and with core biopsy more effective than fine-needle aspiration. Endoscopic biopsy of mediastinal masses is also feasible and effective, although not in the purview of this topic [109]. 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.