CT EVALUATION OF MEDIASTINAL LYMPHADENOPATHY - NONCONTRAST 5 MM VS POSTCONTRAST 10 MM SECTIONS

Objective: Two CT techniques were compared in the assessment of medias tinal lymph nodes: 5 mm thick sections without intravenous contrast me dium and 10 mm thick sections with intravenous contrast medium. Materi als and Methods: Seventy-nine adult patients were examined by chest CT . From the level of the aortic arch through the level of the right mid dle lobe bronchus 5 mm thick sections were performed without intraveno us contrast medium, followed by 10 mm thick sections of the same regio n with intravenous contrast medium. Two chest radiologists separately reviewed each CT method for each patient. Mediastinal lymph nodes were localized according to the American Thoracic Society scheme. Lymph no de diameter was measured on the short axis. Results: The 5 mm thick no ncontrast sections permitted identification of more mediastinal lymph nodes than the 10 mm thick contrast enhanced sections (p < 0.01, signe d rank test). The 5 mm thick unenhanced sections tended to show slight ly (1-2 mm) larger nodes than the 10 mm thick contrast enhanced sectio ns (stations 7, 10R, both reviewers, p < 0.05, signed rank test). Node s with a short axis diameter greater than or equal to 8 mm were identi fied comparably well using either CT technique. Conclusion: The presen t study indicates that CT of the mediastinum using 5 mm thick sections , without intravenous contrast medium, is an appropriate scanning tech nique for evaluation of mediastinal lymphadenopathy.