鼻咽癌复发的增强前后MRI诊断

评价Gd-DTPA增强前后MR I在鼻咽癌放疗后复发(RNPC)与放射性纤维化(RF)鉴别诊断中的作用.材料和方法:对MR平扫显示鼻咽部或邻近区域有软组织肿块的28例鼻咽癌放疗后患者行Gd-DTPA增强MR I检查.RNPC22例,RF6例,炎性肿块2例,2例颅底RNPC分别合并鼻咽侧壁RF与炎性病灶.分析病灶形态及信号强度.结果:大多数RNPC病灶表现为TIWI上低信号TZWI高信号,RF在TIWI和T2WI上均显示低或中等信号,平扫两者信号强度区别在于T2WI上,但有一定重叠.增强扫描TIWI示绝大多数RNPC病灶(90.9%)有中度以上明显强化,而RF无或轻度强化,两者信号强度有显著性差异(P<0.01),且增强后肿瘤边界显示更清楚.病灶无强化,可除外RNPC,有强化则不一定是RNPC,明显强化可见于炎性病变.结论:肿块在MR平扫T2WI和增强后TIWI上的信号强度是鉴别RNPC与RF的主要依据,Gd-DTPA增强扫描有助于确定病变性质及其侵犯范围.

Pre - And Post - Enhaneement MRI in theDiagnosis of Recurrent Nasopharyngeal Carcinoma

Purpose: To evaluate the value of MRI before and afer Gd - DTPA in the differentiation ofrecurrence and fibrosis after radiation of nasopharyngeal carcinoma(NPC). Materials andMethods: Twenty - eight patients with NPC afer radiotherapy were studied with MRI prior toand following the injection of Gd - DTPA. All the patients had a soft - tissue mass in thenasopharynx or adjacent areas. Twenty - two patients had recurrent NPC(RNPC), 6 radiationfibrosis(RF), 2 inflammatory change, of 2 RNPC occurred in association with RF or inflam-mation .The morphology and signal intensity of the lesions were studied. Results: Most RNPCshowed low signal intensity on T1WI and high signal intensity on T2WI. RF remained low ormedian signal intensity on both T1WI and T2WI. The T2WI were helpful in distinguishingRNPC from RF. On the postcontrast T1WI, RNPC (90. 9% ) showed prominent enhancement andRF showed slight or no enhancement. The difference of enhancement between RNPC and RFwas more significant(P < 0. 01). Gd - DTPA enhanced MR also enabled better identification oftumor margin. The mass lesions without enhancement couldn't be HNPC,but the enhancementof tumor was not specific and may be seen in inflammation. Conclusion:The differentiation ofRNPC and RF was based mainly on signal intensity on T2WI and enhanced T1WI .Gd - DTPAenhanced MRI was very useful in the differential diagnosis of HNPC,and could help to definethe extension of tumor.