(1)H MRI of pneumococcal pneumonia in a murine model

PURPOSE: To detect and quantify pulmonary lesions due to pneumococcal pneumonia in a murine model by (1)H MRI. MATERIALS AND METHODS: Pneumonia was induced in mice (N = 5) by intranasal administration of about 1 x 10(6) colony-forming units (CFU) of Streptococcus pneumonie. A group of noninfected animals (N = 5) was used as a control group. MRI was performed, 48 hours after infection induction, at 4.7 T. ECG-gated gradient-echo (GRE) sequences with TE = 5 msec were used. After MRI examination, the animals were sacrificed for histological examination. RESULTS: Lungs appeared at MRI as regions with signal intensity (SI) at the level of the noise. Lesions appeared as hyperintense regions over the background and were localized mainly in the apical part of the lungs, in the medial and peribronchial regions. The anatomical localization of the lesions was confirmed by histology. The total lesion volume quantified by MRI data correlated with the total lesion volume quantified by histology. CONCLUSION: This work shows that standard (1)H MRI allows detection and quantification of lesions due to pneumococcal pneumonia in mice.