Pulmonary nodules and the CT halo sign

Radiology. 1994 Feb;190(2):513-5. doi: 10.1148/radiology.190.2.8284408.


Purpose: To determine whether the "halo sign" at computed tomography (CT) could be used to differentiate hemorrhagic from nonhemorrhagic pulmonary nodules.

Materials and methods: CT scans of 12 patients with hemorrhagic pulmonary nodules and of a control group of 10 patients with nonhemorrhagic pulmonary nodules were randomized and reviewed by two chest radiologists. Nodules were considered hemorrhagic if a surrounding halo of ground-glass attenuation was present.

Results: Nodules were correctly identified as either hemorrhagic or nonhemorrhagic by both observers in 19 of the 22 cases (86%). Eight of the 12 patients with hemorrhagic nodules had an infectious process including invasive aspergillosis, candidiasis, cytomegalovirus, herpes simplex virus, or coccidioidomycosis. Four of 12 patients with hemorrhagic nodules had a noninfectious cause including Wegener granulomatosis, metastatic angiosarcoma, and Kaposi sarcoma.

Conclusion: Most hemorrhagic pulmonary nodules have a characteristic CT appearance consisting of a central area of soft-tissue attenuation with a surrounding halo of ground-glass attenuation that allows distinction from nonhemorrhagic nodules.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Hemorrhage / diagnostic imaging
  • Humans
  • Lung / diagnostic imaging
  • Lung Diseases / diagnostic imaging*
  • Lung Diseases / pathology
  • Lung Neoplasms / diagnostic imaging
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Solitary Pulmonary Nodule / diagnostic imaging*
  • Solitary Pulmonary Nodule / pathology
  • Tomography, X-Ray Computed*