Study Of Diagnosis Value And ADC Value Of Magnetic Resonance Diffusion-Weighted Imaging For Nasopharyngeal Carcinoma And Metastatic Lymph Nodes

Object To study the diagnosis value of magnetic resonance diffusion-weighted imaging for nasopharyngeal carcinoma.Materials and methods The study objects were 53 patients with nasopharyngeal carcinoma and identified by nasopharyngo-fiberoscope from May 2010 to January 2011. All patients underwent routine MR scan, contrast enhanced MR scan and single echo-echo planar imaging diffusion weighted imaging (SE-EPI DWI) scan, and b value is 1000 s/mm2. Another 13 normal person were scanned as control group. The apparent diffusion coefficients (ADC) value was calculated in the primary nasopharyngeal carcinoma site, metastatic lymph nodes and normal lymph nodes. The three groups of ADC data are compared each other by SPSS13.0 in analysis of variance (ANOVA) and t test.Results DWI demonstrated the mass-type nasopharyngeal carcinoma clearly, but hardly demonstrated that of mucosa-type. The detection ratio of metastatic lymph nodes was 100%. The average ADC value of primary nasopharyngeal carcinoma, metastatic lymph nodes and normal lymph nodes was 0.799±0.157×10^-3mm²/s,0.850±0.128×10^-3mm²/s,1.039±0.165×10^-3mm²/s respectively. There was no significant difference between the average ADC value of primary nasopharyngeal carcinoma and metastatic lymph nodes, but there were significant differences between average ADC value of primary nasopharyngeal carcinoma and normal lymph nodes, and between metastatic lymph nodes and normal lymph nodes. And the mean ADC value of nasopharyngeal carcinoma and metastatic lymph nodes was lower than that of normal lymph nodes. When b value was 1000 s/mm², and ROC cut-off point was 0.884×10^-3mm²/s, the diagnostic sensitivity and the specificity in differentiating nasopharyngeal carcinoma and normal lymph nodes was 94.6% and 72.5% respectively. And when ROC cut-off was 0.858×10^-3mm²/s with the same b value, the diagnostic sensitivity and the specificity in differentiating metastatic lymph nodes and normal lymph nodes was 97.3% and 75% respectively.Conclusion Magnetic resonance diffusion weighted imaging and ADC value measure is helpful in diagnosing primary nasopharyngeal carcinoma and differentiating benign and metastatic lymph nodes.