Thin-section CT of Severe Acute Respiratory Syndrome: evaluation of 73 patients exposed to or with the disease

In mid-March 2003, there was an outbreak of atypical pneumonia in one of the wards at our institution in Hong Kong, China. The disease initially affected mainly medical personnel, thus raising alarm that this might be an unusual form of infection. Within 1 week, the number of infected individuals soared and included inpatients and patient relatives, in addition to medical personnel. Cases were beginning to appear in other countries in the region, Europe, North America, and Australia. By the end of the 2nd week, quarantine measures and international travel were substantially altered due to the rapidly rising number of cases. This infection was termed severe acute respiratory syndrome (SARS) and is of unknown etiology, although a coronavirus has been implicated (1). Clinically, the syndrome is defined by the Centers for Disease Control and Prevention (CDC) by three criteria (2): (a) a high fever of more than 38°C and (b) one or more clinical findings of respiratory illness (eg, cough, shortness of breath, difficulty breathing, hypoxia, or radiographic findings of either pneumonia or acute respiratory distress syndrome) and (c) travel within 10 days of onset of symptoms to an area with documented or suspected community transmission of SARS, or close contact within 10 days of onset of symptoms with either a person with a respiratory illness who traveled to a SARS area or a person known to be a suspect SARS case (close contact is defined as having cared for, having lived with, or having had direct contact with respiratory secretions and/or body fluids of a patient suspected of having SARS). Since there is no single test that can be used to diagnose the condition with a reasonable degree of accuracy and reliability, the diagnosis must be based on clinical appearance in combination with imaging features. Chest radiography is one of the major diagnostic components according to World Health Organization and CDC guidelines (3,4). The purpose of our study was to analyze retrospectively the thin-section computed tomographic (CT) features in patients with SARS at our institution