上颌窦炎性假瘤的CT和MRI表现

Features of inflammatory pseudotumor in the maxillary sinus on CT and MRI

目的分析上颌窦炎性假瘤的CT和MRI表现。方法回顾性分析8例经组织学证实的上颌窦炎性假瘤的CT（8例）、MRI（7例）资料，并分析其中3例MR动态增强扫描的时间-信号强度曲线（TIC）。结果病变位于左侧2例，右侧6例；病变均呈不规则形，边界清楚5例、模糊3例，最大径平均51mm（29～72mm）。CT表现：与脑实质比较，平扫6例呈等密度，2例呈略低密度，2例增强后呈中度强化；受累窦壁骨质吸收、破坏，残端骨质伴有硬化。MRI表现：T1WI呈低信号2例、等信号5例；T2WI呈不均匀低信号6例、等信号1例；增强后病变呈不均匀轻度强化2例、中度强化5例；3例动态增强扫描的TIC均为持续上升型。病变累及同侧鼻腔6例、颞下窝和翼腭窝4例、眼眶4例及面颊部3例，MRI更清楚、准确显示窦外蔓延的范围。结论骨质破坏伴有残存骨质硬化、T2WI呈较低信号是上颌窦炎性假瘤较特征性表现；CT和MRI联合使用能够对该病的诊断、治疗及随访提供更全面的信息。

Objective To explore the features of inflammatory pseudotumor in the maxillary sinus on CT and MRI. Methods The CT and MRI data of 8 patients with histology-proven inflammatory pseudotumor in the maxillary sinus were retrospectively analyzed. All 8 patients underwent CT scans and 7 of them also underwent MRI examinations. In addition, the time-intensity curve （TIC） of dynamic contrastenhanced （DCE）MR imaging were analyzed in 3 patients. Results Two cases had lesions in the left maxillary sinus, while the others showed lesions in the right maxillary sinus. All the lesions showed irregular shape with wall-defined margins in 5 cases and hazy margins in 3 cases. The mean maximum diameter of the lesions was 51 mm （ ranged from 29 mm to 72 mm）. On non-enhanced CT, the lesions were isodense to gray matter in 6 and slightly hypodense in 2 patients. Only 2 patients had post-contrast CT with moderate enhancement of their lesions. The lesions caused adjacent bony absorption and destruction with residual bony sclerosis. On MR T1WI, inflammatory pseudotumor showed hypointense in 2 patients and isointense in 5 cases in relative to gray matter. On T2WI, the lesions revealed inhomogeneous hypointense in 6 patients and isointense in 1 patients. Inflammatory pseudotumor showed heterogeneously slight contrast enhancement in 2 cases and moderate enhancement in 5 cases. The TIC showed a steady enhancement pattern in 3 patients. The lesions extended to nasal cavity in 6 cases, pterygopalatine fossa and infratemporal fossa in 4, orbit in 4, and cheek in 3 cases. Six patients underwent follow-up for 2-5 years after surgery and 2 of them were found to have recurrence. In comparison to CT, MRI was proved to show the extent of the lesions more clearly. Conclusions Bony destruction with sclerosis and hypointense signal on MR T2WI are typical manifestations of inflammatory pseudotumor in the maxillary sinus. Combined CT and MRI can provide clinicians with more comprehensive information for the diagnosis, therapy, and follow-up of these lesions.