Computed tomography of tumors involving the atria of the lateral ventricles.

Computed tomograms, angiograms, and operative findings in 18 intra-atrial and 6 para-atrial lateral ventricle tumors were reviewed. Intra-atrial tumors were characteristically homogeneous, with an intraluminal mass effect. The benign types engulfed the choroid glomus; on angiography, the choroidal arteries were enlarged, with a definite tumor blush. Intra-atrial tumors without choroid involvement were usually gliomas. Para-atrial tumors had a low-density center on CT scans (in adults) with an extraluminal mass effect, displaced the glomus, and were avascular on angiography. They were low-grade gliomas in adults and ependymoblastomas in children. Forty non-atrial paraventricular and intraventricular masses were also reviewed. In general, an intraventricular, homogeneous mass which engulfs the choroid glomus on CT and has a significant choroidal artery supply on angiography is of choroidal origin and likely to be benign.