Intersegmental (intersublobar) septum of the lower lobe in relation to the pulmonary ligament: anatomic, histologic, and CT correlations.

A thin horizontal linear area of hyperattenuation that extends laterally from the mediastinal surface of the lung within the area between the inferior pulmonary vein and the diaphragm is a common observation on computed tomographic (CT) scans of the chest. To determine the anatomic basis for this structure, the authors examined four normal human lungs (two right and two left lungs) fixed in an inflated state at pathologic and histologic examination and at CT. The structure in question was identified in one right and two left lungs. The linear area of hyperattenuation seen at CT is a septum of thin, loose intraparenchymal connective tissue that is bounded medially by the base of the pulmonary ligament, where the two sleeves of the visceral pleura appose one another, and laterally by a vertically oriented vein. The septum was identified in 39 of 50 (78%) normal chest CT scans. The pulmonary ligament often appeared to look like a beak at the mediastinal side of the lung. The septum, when visible (n = 39), was bounded medially by the beak in 28 CT scans (72%) and laterally by a vein in 24 scans (62%).

Lymphoma of the mediastinum and neck: evaluation with Ga-67 imaging and CT correlation.

The role of gallium-67 in the differentiation between active disease and fibrotic changes in patients with childhood lymphoma involving the mediastinum and neck was evaluated prospectively. Ga-67 imaging and computed tomography (CT) were correlated with clinical findings at the time of initial presentation and follow-up in 19 patients. Both modalities enabled detection of active disease on all occasions, but CT results were false-positive for residual disease in 10 patients (53%), whereas Ga-67 imaging results were false-positive in only one patient (5%). Neither modality, however, proved accurate in patients with rebound thymic hyperplasia. Ga-67 imaging is a useful tool for assessing response to therapy in children with lymphoma of the mediastinum and neck.