Abstract: Objective To improve the accuracy of preoperative diagnosis by determining the computed tomography(CT)and magnetic resonance imaging(MRI)features of maxillary hemorrhagic necrotizing polyps. Methods We retrospectively reviewed 14 cases of maxillary hemorrhagic necrotizing polyps diagnosed and operated in the last 3 years. We studied the CT and MR images of these patients and determined the imaging features of the disease and the key points for differential diagnosis. Results The main features observed on CT imaging included an expansive lesion that led to bone destruction and a soft tissue mass extending to the middle meatus. The main portion of the lesion had intermediate signal intensity on T₁-weighted imaging(T₁WI)and high signal intensity on T₂WI, surrounded or divided by bands or strips of low signal intensity on T₂WI. The “embryo sign” on enhanced T₁WI is a unique feature of the disease. Some cases have similar CT imaging features to those of fungal sinusitis, inverted papilloma, and maxillary carcinoma. However, these diseases have different features on MRI, which can provide more information for differential diagnosis. Conclusion Compared with CT alone, combined CT and MRI can provide more information on maxillary hemorrhagic necrotizing polyps to enable surgeons to make a more accurate diagnosis before surgery. It is useful in the planning of endoscopic surgery and communicating with patients.

Key words: Maxillary sinus, Inverted papilloma, Hemorrhage, Maxillary sinus neoplasm, Polyps