title: CT halo sign: the spectrum of pulmonary diseases.
abstract: The CT halo sign indicates ground glass attenuation surrounding a pulmonary nodule on CT. Although it was initially proposed as an early, specific finding of invasive pulmonary aspergillosis, it can be caused by many other pathological conditions such as infection, neoplastic and inflammatory diseases. The halo of ground glass attenuation pathologically represents pulmonary haemorrhage, tumour infiltration, or non-haemorrhagic inflammatory processes. Although non-specific, this sign is important because the clinical setting and associated radiological features may give a clue to the differential diagnosis. In this review, we demonstrate the spectrum of pulmonary diseases showing the "CT halo sign" on thin-section CT and discuss their radiological and clinical features.
authors.affiliation: Department of Diagnostic Radiology, College of Medicine, Hanyang University, 17 Haengdang-dong, Sungdong-gu, Seoul 133-792, Korea.
authors.forename: Y R
authors.initials: YR
authors.lastname: Lee
authors.forename: Y W
authors.initials: YW
authors.lastname: Choi
authors.forename: K J
authors.initials: KJ
authors.lastname: Lee
authors.forename: S C
authors.initials: SC
authors.lastname: Jeon
authors.forename: C K
authors.initials: CK
authors.lastname: Park
authors.forename: J-N
authors.initials: JN
authors.lastname: Heo
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*