Halo sign on CT indicative of invasive aspergillosis
NEW YORK (Reuters Health) - The halo sign -- a macronodule with a "halo" of ground-glass opacity around it -- can be a specific indicator of invasive pulmonary aspergillosis on computed tomography (CT), researchers report in the Feb. 1 issue of Clinical Infectious Diseases.
These findings "in patients who are at very high risk of the infection -- patients with underlying hematological malignancy and recipients of bone marrow transplants -- can justify preemptive specific antifungal therapy," lead investigator Dr. Reginald E. Greene told Reuters Health
Greene, of Massachusetts General Hospital, Boston, and colleagues came to this conclusion after analyzing data from 235 invasive pulmonary aspergillosis patients from a previously published study.
The researchers compared outcome in 143 patients who presented with a halo sign -- a macronodule surrounded by a perimeter of ground-glass opacity -- with those in 79 patients with other imaging findings.
Almost all patients (94%) had one or more macronodules at presentation and 61% also had halo signs. Among other common imaging findings were consolidations in 30% and infarct-shaped nodules in 27%.
At 12 weeks, compared to patients with other imaging findings, patients with a halo sign had significantly greater response to treatment (52% versus 29%) and better survival rates (71% versus 53%).
"Our study," Greene continued, "demonstrated that these patients presenting with halo signs, and treated for invasive pulmonary aspergillosis based on the halo sign, are likely to respond better to treatment and have a lower mortality rate than those with nodules that do not have halo signs."
"Although other fungal infections may also exhibit halo signs," he concluded, "they are very much less common than invasive pulmonary aspergillosis as a cause of the sign."
Clin Infect Dis 2007;44:373-379.