Role of imaging in evaluation of lung involvement in severe acute respiratory syndrome (SARS)

Diagnostic imaging played a substantial role in the management and treatment of patients during the Severe Acute Respiratory Syndrome (SARS) outbreak when daily chest radiographs were performed as a measure of disease severity and respiratory status. This thesis was performed to address several issues relating to the radiological spectrum of SARS, its temporal pattern on chest radiograph and high resolution computed tomography (HRCT) during the course of disease, and relationships between severity of opacities quantified on chest radiographs and clinical parameters including treatment response. Radiological parameters that could discriminate SARS from non-SARS community-acquired pneumonia (CAP) were also studied. Unifocal unilateral ground glass opacities was the dominant radiographic abnormality at presentation that progressed rapidly to maximal disease within 9.35 ± 4.09 (median 9, range 3-21) days after onset of symptoms with bilateral consolidation in 62.5% of patients. Complete resolution and significant residual disease was noted in 50% and 20% of cases respectively at end of assessment period. There was a temporal pattern of lung abnormalities on HRCT with ground glass opacity and consolidation at presentation. Reticulation developed after the first week and was present in 50% of patients at ?four weeks. HRCT was useful in illustrating parenchymal abnormalities in patients with normal radiographs at presentation. Severity of lung abnormalities quantified on chest radiograph at different time points of disease correlated with clinical and laboratory parameters such as SaO2 and liver transaminases ALT and AST. Significant relationships were also found between radiographic parameters, and O2 supplementation and treatment response. There are discriminating differences in the radiographic pattern, rate of radiographic progression, and zone of involvement between SARS and non-SARS CAP.published_or_final_versionMedicineMasterDoctor of Medicin