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
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. (Am J Vet Res