High-resolution computed tomography is useful for early diagnosis of severe acute respiratory syndrome-associated coronavirus pneumonia in patients with normal chest radiographs

Objective: We investigated the usefulness of high-resolution computed tomography (HRCT) in early detection of severe acute respiratory syndrome (SARS)-associated coronavirus pneumonia and analyzed HRCT findings associated with potentially more severe disease. Methods: All patients with suspected SARS and normal chest radiographs on admission within the study period were subjected to HRCT examination. The clinical, radiologic, and laboratory data of patients who were confirmed to have SARS-associated coronavirus infection by a positive nasopharyngeal aspirate, stool or urine reverse transcription-polymerase chain reaction (RT-PCR) and/or serological testing were prospectively followed up and analyzed. Characteristics of patients admitted to the intensive care unit (ICU) and those that were not were compared. Results: Among 47 suspected SARS patients with normal chest radiographs, 27 had SARS-associated coronavirus infection confirmed by RT-PCR and/or positive serological testing. Twenty-five of the 27 (93%) patients had HRCT changes compatible with atypical pneumonia, and all 25 patients developed SARS with progressive clinical deterioration. Ten (40%) had unifocal diseases, and 15 had multifocal diseases (60%). Ten (40%) patients had the diseases confined to 1 single lung in the first HRCT, and both lungs were involved at initial presentation in 15 (60%) patients. Concerning the overall extent of the disease at initial presentation, 3 (12%) patients had disease process in all lobes, and the disease was confined to 1 single lobe in 10 (40%) patients. The disease process was mainly peripheral in location (96%), and the lower lobes were more commonly involved (68% in the left lower lobe and 64% in the right lower lobe). Small parapneumonic effusions occurred in 1 (4%) patient. None of the patients with unifocal lesions or single-lung involvement were admitted to the ICU (P < 0.05) (in both comparisons). Subsequent follow-up of the 2 (7%) patients with normal HRCT on admission showed that they were having nonpneumonic SARS-associated coronavirus infection only and were eventually denotified from having SARS. Conclusions: HRCT is useful for early diagnosis of SARS-associated coronavirus pneumonia in patients with normal chest radiographs. HRCT findings in these patients predict potentially severe disease. Key Words: atypical pneumonia, coronavirus, high-resolution computed tomography, severe acute respiratory syndrome