The Efficacy Evaluation Of Nasopharyngeal Carcinoma Undergoing Chemoradiotherapy With Quantitative DCE-MRI And Diffusion-weighted Imaging

Objective: To monitor the change of the quantitative parameters(Ktrans?Kep and Ve)and apparent diffusion coefficient(ADC)value before and after chemoradiotherapy with quantitative DCE-MRI and diffusion-weighted imaging in order to evaluate the efficacy evaluation of nasopharyngeal carcinoma in the functional perspective.Methods: Twenty-six patients with nasopharyngeal carcinoma(NPC)proven pathologically in our hospital from October 2014 to January 2016 were collected,who underwent quantitative DCE-MRI and multi-b-value diffusion-weighted imaging pretreatment and induction chemotherapy then radiotherapy after 50 Gy respectively,and obtained the quantitative parameters(Ktrans ? Kep and Ve)and ADC value respectively.Independent sample t test was used to compare the quantitative parameters(Ktrans?Kep and Ve)and ADC value between the tumor area and normal musculus pterygoideus lateralis.Paired sample t test was used to compare the quantitative parameters(Ktrans?Kep and Ve)and ADC value between pretreatment and posttreatment.Calculat r ADC under the condition of different b values and screen the best b value.Pearson method was used to analyze the correlation of pretreatment nasopharyngeal carcinoma quantitative parameters(Ktrans?Kep and Ve)and ADC value and the tumor regression rate.Results: 1.The Ktrans,Kep and Ve values of Pretreatment tumor area were higher than the normal musculus pterygoideus lateralis,and the differences were statistically significant(P < 0.05).ROC curve analysis results showed that in the differential diagnosis of nasopharyngeal tumor area and normal musculus pterygoideus lateralis,the area under the ROC curve of Ktrans,Kep and Ve were 0.883,0.778,0.814,respectively.0.147 min-1 as Ktrans diagnostic threshold,its sensitivity and speciality degree were 88.5% and 80.8% respectively;0.481 min-1 as Kep diagnostic threshold,its sensitivity and speciality degree were 100% and 57.7% respectively;0.271 as Ve diagnostic threshold,its sensitivity and speciality rate were 73.1% and 73.1%.2.Under the condition of different b values,the ADC values of pretreatment tumor area were lower than the normal musculus pterygoideus lateralis,and the differences were statistically significant(P < 0.05).ROC curve analysis results showed that in the differential diagnosis of nasopharyngeal tumor area and normal musculus pterygoideus lateralis,the area under the ROC curve of ADC700,ADC1000 and ADC1500 were 0.994,0.985 and 0.936,respectively.1.275×10-3 as ADC700 value diagnostic threshold,the sensitivity and speciality degree were 100% and 92.3% respectively;1.105×10-3 mm2/s as ADC1000 value diagnostic threshold,the sensitivity and speciality degree were 96.2% and 92.3% respectively;0.82×10-3 mm2/s as ADC1500 value diagnostic threshold,the sensitivity and speciality degree were 80.81% and 96.2% respectively.3.The Ktrans and Kep of pretreatment nasopharyngeal carcinoma were higher than posttreatment,and the difference were statistically significant(P < 0.05).The Ve of pretreatment nasopharyngeal carcinoma was lower than post-treatment,and the difference was statistically significant(P < 0.05).Uunder the condition of the three different b value,the ADCs of pretreatment nasopharyngeal carcinoma were all lower than post-treatment and the differences were statistically significant(P < 0.05).4.when b Value was 700s/mm2,1000s/mm2,1500s/mm2,the r ADC value was(76.52 ±36.50)%,(76.30 ±37.92)%,(68.10 ± 40.75)%,respectively.r ADC700 was maximum,but the three groups r ADCs between each other have no statistically significant difference(P > 0.05).5.Pretreatment Ktrans,Kep values and induction chemotherapy then radiotherapy after 50 Gy tumor regression rate were positively correlated(P<0.05),and the correlation coefficient r values were 0.544,0.395,respectively.There were no significant correlation between pretreatment Ve,ADC values and the tumor regression rate(P > 0.05).Conclusion: 1.Quantitative DCE-MRI and DWI can reflect the differences between nasopharyngeal tumor and normal tissue around by measuring Ktrans,Kep,Ve and ADC values,so that they can judge the surrounding invasion of tumor to some extent.In the three parameters of quantitative DCE-MRI,the differential diagnosis value of Ktrans was the best.In the three b value of DWI,700s/mm2 was the best.2.Monitoring Ktrans,Kep,Ve values dynamically can judge the response of tumor to therapy intuitively.In addition,through analyzing the correlation between the pretreatment nasopharyngeal carcinoma quantitative parameters(Ktrans?Kep and Ve)and ADC value and the induction chemotherapy plus radiotherapy after 50 Gy tumor regression rate,the results showed that the pretreatment Ktrans,Kep values and the tumor regression rate were positively correlated(P < 0.05),and the correlation coefficient r values were 0.544,0.395,respectively.The research suggested that pretreatment Ktrans,Kep can predict the efficacy evaluation of nasopharyngeal carcinoma to some extent and Ktrans was better.3.DWI can predict the efficacy evaluation of nasopharyngeal carcinoma to some extent.In three groups(700s/mm2,1000s/mm2 and 1500s/mm2),combining the image quality and the r ADC values,we comprehensively consider that the 700s/mm2 was the best b value in evaluating efficacy evaluation of nasopharyngeal carcinoma.4.Quantitative DCE-MRI and DWI can assesst the efficacy of nasopharyngeal carcinoma quantitatively in the different perspective of the pathophysiology,so that the clinical treatment and drug dose can be adjusted in time.