CT and MR imaging of the paranasal sinuses in cystic fibrosis - Correlation with microbiological and histopathological results

Purpose. To compare CT and MR findings of the paranasal sinuses in patients with cystic fibrosis (CF) with microbiology and histopathology. Further, t o compare microbiology from the maxillary sinuses, nasopharynx and sputum. Material and Methods: CT and MR imaging of the paranasal sinuses were perfo rmed in 10 CF patients. Endoscopy and maxillary sinus aspirates were obtain ed (guided by the MR findings) and analyzed microbiologically and histologi cally. Samples from the nasopharynx and sputum were analyzed microbiologica lly. Results. CT and MR were equal in displaying the extent of soft tissue masse s, which at CT were homogeneous, while MR showed heterogeneous signals. MR images also demonstrated circumscribed areas with signal void at the STIR s equence with corresponding high to intermediate signal at the T1-weighted s equence. P. aeruginosa was frequently cultured from these areas which we na med the "black hole sign" Maxillary sinus cultures revealed the same bacter ia as nasopharynx and sputum cultures combined. Conclusion. MR images were superior to CT in differentiating soft tissue ma sses in the paranasal sinuses in CF patients. Bacteria with potential for s pecialized iron uptake mechanisms were present in areas with signal void at the STIR sequence. Our hypothesis is that the MR "black hole sign" can be explained by paramagnetic properties related to bacterial agents.