The Value Of Diffusion-weighted Of3.0T MR Imaging For Nodal Staging And Prediction Of Chemoradiotherapy In Nasopharyngeal Carcinoma

Objective: To investigate the value of multi b-Values diffusion-weighted of3.0T MR imaging (DW-MRI) for nodal staging innasopharyngeal carcinoma (NPC).Materials and Methods:45cases with NPC confirmed by pathologicalbiopsy and15cases with benign lymph nodes underwent conventional MRscanning and DWI using b=600s/mm2,800s/mm2,1000s/mm2. An imagequality score criterion was taken into consideration for evaluating the DWIimaging for each b values, image quality was rated four point scale (1=poor，2=moderate,3=good,4=excellent). Apparent diffusion coefficient (ADC)values of each b-value were measured for NPC primary lesions, metastaticand benign cervical lymph nodes. SPSS13.0statistics software is used forStatistical analysis.Results:1. The scores of image quality was2.84±0.767,3.2±0.588,2.89±0.714for b=600s/mm2,800s/mm2,1000s/mm2respectively. The image quality wasbest when b=800s/mm2. there were significant difference comparing b=800s/mm2with b=600s/mm2or b=1000s/mm2(P＜0.05). There weren’tsignificant difference between b=600s/mm2and1000s/mm2in image qualityscore (P＞0.05).2. The ADC values decreased with b values increasing in nasopharyngealcarcinoma primary tumors, metastatic and benign lymph nodes. There weren’t significant difference between ADC of nasopharyngeal carcinoma primarytumors and metastatic lymph nodes, but there were significant differencebetween ADC of metastatic and benign lymph nodes for three b-values (P＜0.05). ADC values obtained on b=800s/mm2could be best to discriminatemetastatic and benign lymph nodes (cutoff,0.938×10-3mm2/s), with areaunder ROC curve of was0.988, sensitivity of100%and specificity of83.3%,respectively.Conclusion: DW-MRI of3.0T could be help for evaluation ofmetastatic lymph nodes and it has important significance for nodal staging innasopharyngeal carcinoma. The DW imaging was best visible on b=800andADC with b=800was best to distinguish metastatic and benign lymph nodes. Objective: To explore the value of diffusion-weighted of3.0T MRimaging (DW-MRI) for prediction of chemoradiotherapy sensitivity innasopharyngeal carcinoma (NPC).Materials and Methods:32cases with NPC confirmed by pathologicalbiopsy underwent conventional MR scanning and multi b-Values DWI.Apparent diffusion coefficient (ADC) values were obtained on DWI withb=800, volumes of NPC primary tumors and metastatic lymph nodes weremeasured on enhanced T1WI before CRT and CRT at5weeks.32cases of NPC were grouped into hypersensitivity and hyposensitivity group based onthe CRT effect. ADC values, rate of change for ADC values(△ADC)，andvolume of fading rate（△V）of hypersensitivity and hyposensitivity groupwere measured before CRT and CRT at5weeks. Logistic regression analysiswas used to predict sensitivity of NPC chemotherapy and its relatedinfluential factors.Results:1. The volume of NPC and metastatic lymph node were15.46±9.67cm3,7.96±2.68cm3before CRT, the volume of NPC and metastatic lymph nodewere5.39±4.53cm3,0.85±0.76cm3after5weeks CRT,△V of NPC andmetastatic lymph node were (67.28±11.69)%,(91.00±6.83)%. There weresignificant difference in volume of NPC and metastatic lymph node betweenbefore and after CRT (P <0.05).2. ADC values of NPC and metastatic lymph node increased after CRT.ADC values of metastatic lymph node increased more obviously than primaryNPC. The ADC of NPC and metastatic lymph node were（0.856±0.084）×10-3mm2/s,（0.876±0.144）×10-3mm2/s before CRT, The ADC of NPC andmetastatic lymph node were（1.735±0.168）×10-3mm2/s,（1.830±0.162）×10-3mm2/s when CRT5weeks,△ADC of NPC and metastatic lymph nodewere (104.46±26.97)%,(116.14±30.76)%. There were significant differencein ADC of NPC and metastatic lymph node between before and after CRT (P<0.05).3. The ADC,△ADC and△V value of hypersensitivity group NPC were（1.793±0.101）×10-3mm2/s,(117.83±16.80)%,(71.26±11.68)%, and thevalue of hyposensitivity group NPC were （1.609±0.219）×10-3mm2/s, (75.06±20.32)%,(61.46±9.27)%respectively. Three were statisticallydifference between the two groups(P＜0.05),△ADC was the best todiscriminate the two groups (cutoff,98.125%),with area under ROC curve ofwas0.973, sensitivity of95.5%, specificity of90%.4. Nonlinear Logistic regression analysis about the related clinicalfactors (sex, age, treatment, T stage and△ADC) showed that△ADC wasdependent variable for effecting CRT sensitivity of NPC, the relative riskcapacity was1.155. After5weeks CRT, the higher the△ADC was, the moresensitivity to CRT.Conclusion: DWI play an important role in evaluating response to CRTin NPC. ADC value,△V and△ADC of NPC could predict the CRTsensitivity when CRT5weeks.△ADC could be the best indicator forprediction CRT sensitivity of NPC and be a dependent variable for effectingCRT sensitivity of NPC.