OBJECTIVE: To determine correlation between results of computed tomography (CT) versus pathologic examination for determining the volume percentage of affected lung in mice experimentally infected with Pasteurella pneumotropica. ANIMALS: 30 adult mice. PROCEDURE: After helical CT scans on day 0, mice were inoculated intranasally with P. pneumotropica. Repeat CT scans were performed on days 1, 2, 3, 4, 6, 8, 10, and 13. Regions of interest (affected areas) were manually drawn on the CT images, and percentage volume of normal lung was calculated by use of 3 methods: first-day volume, largest volume, and last-day volume. Three mice were euthanatized for pathologic evaluation after each scan day. The lungs were examined with a dissection microscope, and lesion scores were assigned on the basis of percentage volume of pneumonia. Correlation coefficients comparing results of the 3 CT methods with results of gross examination were calculated. RESULTS: Lung abnormalities were detected via dissection microscopy by postinfection day 2 and via CT by days 2 or 3. Correlation coefficients for the 3 CT methods of analysis, compared with pathologic findings, were 0.7 via first-day lung volume, 0.8 via largest lung volume, and 0.8 via last-day lung volume. CONCLUSIONS AND CLINICAL RELEVANCE: Results of CT correlated well with results of dissection microscopy for estimating percentage volume of lung affected by pneumonia in mice experimentally infected with P. pneumotropica. This method may be useful for longitudinal studies of pneumonia in mice.
OBJECTIVE: To determine correlation between results of computed tomography (CT) versus pathologic examination for determining the volume percentage of affected lung in mice experimentally infected with Pasteurella pneumotropica. ANIMALS: 30 adult mice. PROCEDURE: After helical CT scans on day 0, mice were inoculated intranasally with P. pneumotropica. Repeat CT scans were performed on days 1, 2, 3, 4, 6, 8, 10, and 13. Regions of interest (affected areas) were manually drawn on the CT images, and percentage volume of normal lung was calculated by use of 3 methods: first-day volume, largest volume, and last-day volume. Three mice were euthanatized for pathologic evaluation after each scan day. The lungs were examined with a dissection microscope, and lesion scores were assigned on the basis of percentage volume of pneumonia. Correlation coefficients comparing results of the 3 CT methods with results of gross examination were calculated. RESULTS:Lung abnormalities were detected via dissection microscopy by postinfection day 2 and via CT by days 2 or 3. Correlation coefficients for the 3 CT methods of analysis, compared with pathologic findings, were 0.7 via first-day lung volume, 0.8 via largest lung volume, and 0.8 via last-day lung volume. CONCLUSIONS AND CLINICAL RELEVANCE: Results of CT correlated well with results of dissection microscopy for estimating percentage volume of lung affected by pneumonia in mice experimentally infected with P. pneumotropica. This method may be useful for longitudinal studies of pneumonia in mice.