Background Studies on intrathoracic tuberculous lymphadenitis in adults are confined to the preliminary CT findings with ordinary CT and ordinary spiral CT.There has been no deepgoing study of multidetector CT to date.Multidetector CT could contribute to better imaging of intrathoracic tuberculous lymphadenitis in adults.The purpose of this study was to explore the multidetector CT features of intrathoracic tuberculous lymphadenitis in adults, and the correlation with clinical symptoms and pathologic changes.Methods Multidetector CT findings from 42 consecutive adult patients with intrathoracic tuberculous lymphadenitis were analyzed retrospectively with regard to locations, sizes, numbers, shapes, margins, and densities reviewing precontrast and enhanced images.CT results were correlated with clinical symptoms and pathologic results (n=37).Results One hundred and eighty-five intrathoracic lymph nodes that had tuberculous lymphadenitis in 42 patients were distributed mainly in regions 4R (n=37), 2R (n=33), 7 (n=31) and 10R (n=21), more than 2 regions were implicated in 34 patients.One hundred and twenty-two (72.2%) of the tuberculous lymphadenitis without confluence were oval or round with clear margins.On precontrast scanning, 78.4% of tuberculous lymphadenitis had a homogeneous density.Seven enhancement patterns were demonstrated in 169 tuberculous lymphadenitis from 37 patients with pathologic results:homogeneous enhancement with no clinical symptom (n=12), corresponded pathologically to tuberculous hyperplasia without caseous necrosis; heterogeneous enhancement with a small central no enhancement area, slight clinical symptoms (n=22), tuberculous granulomas with a little caseous necroses; peripheral irregular thick wall enhancement with a central area with no enhancement, slight clinical symptoms (n=52), tuberculous granulomas with some caseous necroses in the center; peripheral thin rim enhancement with a central area having no enhancement, moderate clinical symptoms (n=36), a few tuberculous granulomas with a great quantity of caseous necroses in the center; peripheral irregular enhancement without central enhancement, extending outside the capsule, severe clinical symptoms (n=4),caseous necroses ruptured from capsule; peripheral irregular rim enhancement with central separate enhancement,severe clinical symptoms (n=40), multiple lymph nodes with liquefaction of caseous necroses were adherent and confluent, rim and separation were tuberculous granulomas; no obvious enhancement, severe clinical symptoms (n=3).Caseous necrosis was usually associated with little tuberculous granulomas.Conclusions The main multidetector CT features of intrathoracic tuberculous lymphadenitis in adults are involvement of multiregional lymph nodes with oval or round shape and clear margins, a basically homogeneous density on precontrast scanning, multiple enhancement patterns, and they correlate closely with clinical symptoms.Multidetector CT could reveal pathological changes of intrathoracic tuberculous lymphadenitis in adults.