Ground-glass opacification Computed tomographic halo sign 2020-04-25T13:12:15Z CT finding of ground-glass opacity surrounding a nodule or mass. It was first described as a sign of hemorrhage around foci of invasive aspergillosis. The halo sign is nonspecific and may also be caused by hemorrhage associated with other types of nodules or by local pulmonary infiltration by neoplasm. CT halo sign