鼻腔及鼻窦内翻性乳头状瘤的MRI诊断

MRI diagnosis of sinonasal inverted papilloma

目的探讨鼻腔、鼻窦内翻性乳头状瘤的MRI表现，提高其诊断准确性。方法回顾性分析36例经组织学证实的鼻腔、鼻窦内翻性乳头状瘤的MRI资料。结果36例内翻乳头状瘤源于鼻腔外侧壁25例，上颌窦4例，筛窦2例，额、筛窦2例，筛、蝶窦2例，额窦1例；其中11例为复发病例，3例伴恶变。26例呈分叶状，10例形状不规则。病灶最大径22～82mm，平均38mm。36例边界均清楚。与邻近肌肉比较，MRT1WI呈等信号32例，稍高信号4例；T2WI呈不均匀高信号34例，不均匀等信号2例（伴恶变）。与鼻中隔黏膜比较，增强后呈明显不均匀强化34例；32例病变在T2WI或增强T1WI上病变内部呈较规整的栅栏状，2例呈不规整的栅栏状（伴恶变）。8例行MR动态增强扫描，其中7例时间一信号强度曲线（TIC）为速升缓降型，另1例局部区域的曲线呈速升速降型（伴恶变）。结论MRT2WI或增强T1WI上呈较规整的栅栏状外观是诊断鼻腔、鼻窦内翻性乳头状瘤的可靠征象，形态不规整可能提示伴发恶变。

Objective To investigate the MRI findings of sinonasal inverted papilloma so as to promote the diagnostic accuracy. Methods All 36 cases of sinonasal inverted papilloma were verified by pathology. Their MRI findings were analyzed retrospectively. Results The lesion occurred in the lateral nasal wall in 25 cases, in the maxillary sinus in 4 cases, in the ethmoid sinus in 2 eases, in the frontal and ethmoid sinuses in 2 cases, in the ethmoid and sphenoid sinuses in 2 cases and in the frontal sinus in one case. Of the 36 cases, 11 cases had recurrent lesions and 3 cases were associated with malignant change. All lesions showed well-defined margin, with lobulate configuration in 26 eases and irregular shape in 10 cases. The diameter of the lesions ranged from 22 to 82 mm （mean, 38 ram）. On MR TIWI, sinonasal inverted papilloma revealed isointense signal compared to adjacent muscle in 32 cases and slight hyperintense signal in 4. On T2WI, the lesions showed heterogeneous hyperintense signal in 34 cases and inhomogeneous isointense signal in 2 cases with malignant change. Postcontrast MR imaging demonstrated marked inhomogeneous enhancement compared with nasal septum mucosa in 34 cases. Regular fence-like pattern was found on MR T2WI and enhanced T1WI in 32 cases, while irregular ones were found in three cases with malignant change. The time-intensity curve （TIC） of dynamic contrast enhancement of MRI showed rapid enhancing and slow wash-out type in 7 cases, while rapid enhancing and wash-out pattern was detected in one case with malignant change. Conclusion Regular fence-like pattern on MR T2WI or enhanced T1WI was reliable characteristics for the diagnosis of sinonasal inverted papilloma. Irregular ones may suggest malignant change.