Pupose To explore the role of histogram analysis of apparent diffusion coefficient (ADC) maps obtained from multiple b value diffusion weighted imaging (DWI) in the assessment of progression of high-grade glioma (HGG) treated with chemoradiotherapy so as to determine the optimal b value.Materials and Methods Forty-one consecutive patients with HGG proved histopathologically who had undergone concurrent chemoradiotherapy at Second Hospital of Hebei Medical University from September 2014 to October 2015 were enrolled in the study.All the subjects underwent diffusion weighted MR imaging before and after therapy with b values of 0,1000,2000 and 3000 s/mm2.Based on the clinical and radiographic follow-ups,the patients were divided into progression and nonprogression groups.ADC maps were calculated according to hyperintense FLAIR lesions after completion of chemoradiotherapy.The fifth percentile (C5) in terms of cumulative histograms in different b-value ADC maps in multiple b value DWI was calculated,and the C5 of each ADC map between progression and non-progression groups was compared.Moreover,receiver operating characteristic analysis was used to determine the best cutoff values and diagnostic accuracy for predictors in the differentiation of true progression from non-progression.Results The C5 of all different b value ADC maps were significantly lower in the progression group than those in the non-progression group (P＜0.01).In terms of the accuracy of assessing the progression after therapy,the C5 in the high b value ADC maps was significantly higher than that in the low b value ADC maps.The area under the receiver operating characteristic curve (AUC) of the C5 was 0.717,0.832,0.909,0.933 and 0.937 respectively in the 5 ADC maps [ADC(1000/0),ADC(2000/0),ADC(30000/0,ADC(3000/1000) and ADC(3000/2000)].When the cutoff value of C5 was 405.6 mm/s2 in ADC(3000/2000) map,the sensitivity,specificity,positive predictive value and negative predictive value were 90.9％,89.7％,89.9％ and 91.0％,respectively.Conclusion The C5 in ADC map can effectively differentiate tumor progression of HGG,and that of high b values have higher accuracy.

Objective To evaluate the application value of ADC of different b-value ADC maps in multiple b-value DWI for assessment of early treatment response and detection of tumor progression.Methods Totally 47 postoperative patients with glioma were enrolled.All of them accepted chemoradiotherapy after operation.Conventional MRI and multiple b-value DWI (b=0,1 000,2 000,3 000 s/mm2) scans were performed.The mean and minimal ADC values (ADC and ADCrmin) were measured in 5 differrent corresponding ADC maps,such as ADC(1 000/0),ADC(/2 000/0),ADC(3 000/0),ADC(3 000/1000） and ADC(3 000/2 000).And the relative values (rADC and rADCmin) were calculated.The differences of ADC values among different reaction types (complete response,partial response,stable disease and progressive disease)and between progressive and non-progressive groups were compared.ROC analysis was used to determine the best cutoff values and diagnostic efficiency of ADC value for diagnosis of tumor progression.Results The rADC in ADC(3 000/0),ADC(3 000/1000） and ADC(3 000/2 000) maps were significantly different among different response types and between progressive group and non progressive group (all P＜0.05).The ADC in ADC(3 000/1000） and ADC(3000/2 000) maps were significantly different among different response types and between progressive group and non-progressive group (all P＜0.05).The ADC and rADC in ADC(3 000/2 000) map had the maximum area under curve (0.86,0.84).When ADC and rADC in ADC3 000/2 000 map were 408.65 × 10-6 mm2/s and 1.12,the sensitivities and specificities were 89.3 ％0,71.0 ％00 and 92.9 ％,77.4 ％,respectively.Conclusion The ADC and rADC in high b-value ADC maps are helpful to discriminate the early treatment response from tumor progression,which can provide valuable information for identification of tumor progression of glioma after treatment.