Complementary role of MR imaging of ethmomaxillary sinus disease depicted at CT in cystic fibrosis

Purpose: To assess whether MR imaging can improve characterization of ethmo maxillary opacification diagnosed at CT in patients with cystic fibrosis (C F) in order to select patients that may benefit from functional endoscopic sinus surgery (FESS). Material and Methods: Sixty-two CF patients (26 females and 36 males) aged 4-50 years (median 20 years) with ethmomaxillary sinus disease at CT underw ent MR examination of the paranasal sinuses (coronal T1 and STIR sequences) . FESS had been performed in 28 of the patients prior to this study. MR sig nal intensities were interpreted as mucosal thickening or infectious materi al, according to a previous study. Results: Three major maxillary sinus MR patterns could be distinguished: Ai r-filled, oval-shaped pus-filled, and streaky-shaped pus-filled sinus lumen . For air-filled maxillary sinuses with mucosal thickening, CT and MR imagi ng were diagnostically equivalent. Where CT showed homogeneous opacificatio n of the maxillary sinuses, MR imaging differentiated between thickened muc osa and pus-filled areas. Patients who had undergone FESS most commonly had air-filled or streaky-shaped pus-filled maxillary sinus lumen. In non-oper ated patients oval-shaped pus-filled sinus lumen was most common and could occur without ethmoid disease. Conclusion: MR imaging of the paranasal sinuses can differentiate between i nfectious material and thickened mucosa and should be used to select CF pat ients with pus-filled areas that can be eradicated with FESS.