title: Severe acute respiratory syndrome: radiographic appearances and pattern of progression in 138 patients.
abstract: OBJECTIVE
  To retrospectively evaluate the radiographic appearances and pattern of progression of severe acute respiratory syndrome (SARS).
  
  
  METHODS
  Chest radiographs obtained at clinical presentation and during treatment in 138 patients with confirmed SARS (66 men, 72 women; mean age, 39 years; age range, 20-83 years) were assessed. Radiographic appearances of pulmonary parenchymal abnormality, distribution, and extent of involvement on initial chest radiographs were documented. Recognizable patterns of radiographic progression were determined by comparing the overall mean percentage of lung involvement for each patient on serial radiographs.
  
  
  RESULTS
  Initial chest radiographs were abnormal in 108 of 138 (78.3%) patients and showed air-space opacity. Lower lung zone (70 of 108, 64.8%) and right lung (82 of 108, 75.9%) were more commonly involved. In most patients, peripheral lung involvement was more common (81 of 108, 75.0%). Unifocal involvement (59 of 108, 54.6%) was more common than multifocal or bilateral involvement. No cavitation, lymphadenopathy, or pleural effusion was demonstrated. Four patterns of radiographic progression were recognized: type 1 (initial radiographic deterioration to peak level followed by radiographic improvement) in 97 of 138 patients (70.3%), type 2 (fluctuating radiographic changes) in 24 patients (17.4%), type 3 (static radiographic appearance) in 10 patients (7.3%), and type 4 (progressive radiographic deterioration) in seven patients (5.1%). Initial focal air-space opacity in 44 of 59 patients (74.6%) progressed to unilateral multifocal or bilateral involvement during treatment.
  
  
  CONCLUSIONS
  Predominant peripheral location; common progression pattern from unilateral focal air-space opacity to unilateral multifocal or bilateral involvement during treatment; and lack of cavitation, lymphadenopathy, and pleural effusion are the more distinctive radiographic findings of SARS.
authors.affiliation: Department of Diagnostic Radiology, Prince of Wales Hospital, Chinese University of Hong Kong, 30-32 Ngan Shing St, Shatin, Hong Kong SAR. wongkatakjeffrey@hotmail.com
authors.forename: K T
authors.initials: KT
authors.lastname: Wong
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Antonio
authors.forename: David S C
authors.initials: DS
authors.lastname: Hui
authors.forename: Nelson
authors.initials: N
authors.lastname: Lee
authors.forename: Edmund H Y
authors.initials: EH
authors.lastname: Yuen
authors.forename: Alan
authors.initials: A
authors.lastname: Wu
authors.forename: C B
authors.initials: CB
authors.lastname: Leung
authors.forename: T H
authors.initials: TH
authors.lastname: Rainer
authors.forename: Peter
authors.initials: P
authors.lastname: Cameron
authors.forename: Sydney S C
authors.initials: SS
authors.lastname: Chung
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D045169:Severe Acute Respiratory Syndrome / Q000000981:diagnostic imaging*