US Chest There is little relevant literature to support US of an indeterminate mediastinal mass on 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]. 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].
Imaging of Mediastinal Masses. US Chest There is little relevant literature to support US of an indeterminate mediastinal mass on 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]. 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].