Fine-needle aspiration of posterior mediastinal lesions guided by radial scanning endosonography

Abstract

Endoscopic ultrasound (EUS) has been a major technological advance in the area of gastrointestinal wall imaging. The instruments incorporate a highfrequency ultrasound transducer, which provides high-resolution images sufficient to identify five separate echo layers of the gastrointestinal tract wall that have histologic correlates, i These high-resolution images permit accurate staging of gastrointestinal tract tumors including esophageal, gastric, pancreatic, and rectal tumors. Recently, it has been shown that EUS can be used to image the posterior mediastinum to evaluate periesophageal masses or to look for lymphadenopathy in patients with esophageal cancer or non-small cell lung cancer (NSCCA). 2 Patients with NSCCA and contralateral mediastinal lymph node metastasis or large subcarinal lymph nodes (>2.0 cm) are not surgical candidates. 3, 4 EUS criteria that are considered suggestive for malignant lymph nodes include sharply demarcated borders, round shape, homogeneous hypoechoic echo pattern, and size greater than 1 cm. 5, 6 However, when these criteria are applied, they provide an accuracy of only 60% to 80%. If the presence of malignant lymph nodes will significantly alter the treatment of a patient, then it becomes necessary to more accurately determine lymph node status. This can be accomplished with direct sampling of lymph nodes using fine-needle aspiration (FNA) techniques. 7 Echoendoscope systems are currently available in two different transducer designs: curved linear array (Pentax, Orangeburg, N.Y.) and 360 ° radial scanning (Olympus America, Melville, N.Y.) (Fig. 1). The linear array system offers the ability to perform FNA while