CT and MRI diagnosis of hemorrhagic and necrotic nasal polyps / 中华放射学杂志

ABSTRACT

Objective To study the CT and MRI findings of hemorrhagic and necrotic nasal polyps. Methods The imaging data of 17 cases with hemorrhagic and necrotic nasal polyps confirmed by surgery and pathology were analyzed retrospectively. CT was performed in 14 cases, MRI in 16 cases, of which 15 also underwent contrast-enhanced MRI. Results All 17 lesions with well-circumscribed margin originated in the areas of maxillary sinus ostia and extended into adjacent nasal cavity and maxillary sinus. The lesions appeared as lobular shape in 16 cases and oval shape in 1 case. On non-enhanced CT, 14 lesions showed heterogenous soft tissue density masses, the hyperdense strip and nodule were detected on the periphery and in the center of 2 lesions respectively. All the involved bony walls were compressed and remodeled with focal defect,especially in the medial wall of maxillary sinus. On MRI, all 16 lesions revealed inhomogenous signal. The central region of the lesions appeared hypointense signal on T_1WI compared to gray matter and hyperintense signal on T_2WI with line-like hypointense signal septa in 14 cases, the irregular hypointense signal rims were also found on the periphery of 15 lesions on T_2WI, postcontrast MR imaging showed strongly inhomogenous enhancing masses with non-enhancing hypointense rim, the appearances of enhancement showed multiple nodules in 10 cases, patches in 4 cases and leaf-like in 1 case. The typical simple polyps were present in the ipsilateral nasal cavity of the lesions in 4 cases, extending into nasal vestibule anteriorly and choana posteriorly. On dynamic contrast-enhanced MRI in 11 cases, the timeintensity curves (TIC) showed increasing enhancement type in 7 cases and rapid enhancement and slow wash-out type in 4 cases. Conclusion The inhomogenous hyperintensity surrounded by the peripheral hypointense rim on MR T_2WI and marked nodular and patchy enhancement appearance are typical features of hemorrhagic and necrotic nasal polyps. CT is helpful to judge the nature of lesions, but difficultly confirms the diagnosis, while MRI should be the imaging modality of first choice for hemorrhagic and necrotic nasal polyps.