目的：通过MR扩散加权成像在鼻咽癌随访中帮助内窥镜提高活检阳性率。方法：135例鼻咽癌治疗后随访可疑复发但首次内窥镜活检却没有发现癌组织的病例，再次行内窥镜活检前均行MR常规序列及扩散加权序列检查，通过观察MR图像对鼻咽活检部位进行定位，分为MR-A定位（MR常规序列）、MR-B定位（MR常规序列结合扩散加权序列）。然后再次内窥镜活检，先单独依据内窥镜影像（内镜定位）进行1次活检，然后再分别根据MR-A定位、MR-B定位各进行1次活检。通过与定性结果比较，分析3种定位方式的诊断价值，以及定位一致性对于2种MR定位的影响。结果：135例样本最终定性复发56例、未复发79例。内镜定位、MR-A定位、MR-B定位分别发现阳性26例、33例、40例，阴性109例、102例、95例，敏感度为46.4%、58.9%、71.4%，特异度均为100%，Az值分别为0.732、0.795、0.857。由于特异度均为100%，因此只分析复发病例。2种MR定位方式之间亦存在相关性（χ2=4.250，P=0.039，Kappa=0.265）。56例复发病例中，2种MR方式定位32例活检部位一致，24例活检部位不一致。活检方向一致性对MR-A定位的结果存在显著性影响（χ2=5.171，P=0.023，rp=0.304），对MR-B定位的结果不存在显著性影响（χ2=0.007，P=0.932，rp=0.011）。当活检方向不一致时，MR-A定位的阳性率41.7%（10/24）小于MR-B定位的阳性率70.8%（17/24），存在显著性差异（χ2=4.148，P=0.042）。结论：在鼻咽癌随访中，MR辅助定位可以帮助鼻咽癌内窥镜提高活检结果的准确率、降低漏诊率，而以MR扩散加权成像辅助定位的价值更大。

Objective: To improve the positive rate of endoscopic biopsy in follow-up of nasopharyngeal carcinoma(NPC) through MR diffusion weighted imaging. Methods: In the follow-up of NPC after treatment, 135 cases with suspicious recurrent were found negative result in the first endoscopic biopsy, then were performed with MR routine sequence and diffusion weighted sequence scanning before the second endoscopic biopsy. Through observing MR images, the positions of nasopharyngeal biopsy were decided, including MR-A location(MR routine sequence) and MR-B location(MR routine sequence and diffusion weighted sequence). In the second endoscopic biopsy, the tissue particle was obtained according to endoscope image(endoscopic location), and then each tissue particle was gotten according to MR-A and MR-B locations. The diagnostic value of the 3 kinds of locations and the influence of location consistency on the 2 kinds of MR locations were analyzed by comparing with the qualitative results. Results: in 135 cases, 56 cases were eventually confirmed for recurrence, 79 cases for no recurrence. Endoscopic location, MR-A location and MR-B location were found positive in 26 cases, 33 cases, 40 cases, negative in 109 cases, 102 cases, 95 cases, the sensitivity for 46.4%, 58.9%, 71.4%, the specificity all for 100%, Az values for 0.732, 0.795, 0.857. Because of the specificities all were 100%, the recurrence cases were analyzed. There was a correlation between the 2 kinds of MR locations(χ2=4.250, P=0.039, Kappa=0.265). In 56 cases with recurrence, biopsy sites of 2 MR locations were consistent in 32 cases and inconsistent in 24 cases. The consistency of biopsy directions had significant effects on the results of MR-A location(χ2=5.171, P=0.023, rp=0.304) and had no significant effects on the results of MR-B location(χ2=0.007, P=0.932, rp=0.011). When the biopsy directions were inconsistent, the positive rate of MR-A(41.7%, 10/24) was less than that of MR-B(70.8%, 17/24), there was significant difference(χ2=4.148, P=0.042). Conclusions: During the follow-up of NPC, MR assisted localization can help nasopharyngeal endoscope biopsy to improve the accuracy rate and reduce the misdiagnosis rate, and MR diffusion weighted imaging has greater value in the auxiliary positioning.