Objective To observe the value of reduced field-of-view(rFOV)diffusion weighted imaging(DWI)for differentiating low-risk and high-risk thymoma.Methods A total of 145 patients with pathologically confirmed thymoma were retrospectively collected,among them there were 96 cases of low-risk thymoma(low-risk group,including 33 cases of type A,29 cases of type AB and 34 cases of type B1 thymoma)and 49 cases of high-risk thymoma(high-risk group,including 26 cases of type B2 and 23 cases of type B3 thymoma).Conventional single-shot echo planar imaging(SSEPI)and ZOOMit sequence DWI before treatment were compared,and subjective scoring based on displaying of anatomical structures,thymoma lesions,image artifacts and overall diagnosis confidence were performed,so did objective evaluation according to image signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of 2 kinds of images.The apparent diffusion coefficient(ADC)obtained with DWI were compared between groups.Receiver operating characteristic(ROC)curve was drawn,and area under the curve(AUC)was calculated to analyze the efficacy of ADC for differentiating low-risk and high-risk thymoma.Results Subjective scores of displaying anatomical structures,thymoma lesions,image artifacts and overall diagnosis confidence of ZOOMit were all superior to those of SSEPI(all P＜0.001),while SNR and CNR of ZOOMit were both higher than those of SSEPI(all P＜0.001).There were statistical differences of ADCSSEPI and ADCZOOMit between groups(both P＜0.001).The AUC of ADCssEPI and ADCZOOMit for distinguishing low-risk and high-risk thymoma was 0.865 and 0.922,respectively,of the former was higher than of the latter(Z=2.091,P=0.037).Conclusion rFOV DWI could be used to differentiate low-risk and high-risk thymoma.

Objective To observe the value of reduced field-of-view(rFOV)diffusion weighted imaging(DWI)for differentiating low-risk and high-risk thymoma.Methods A total of 145 patients with pathologically confirmed thymoma were retrospectively collected,among them there were 96 cases of low-risk thymoma(low-risk group,including 33 cases of type A,29 cases of type AB and 34 cases of type B1 thymoma)and 49 cases of high-risk thymoma(high-risk group,including 26 cases of type B2 and 23 cases of type B3 thymoma).Conventional single-shot echo planar imaging(SSEPI)and ZOOMit sequence DWI before treatment were compared,and subjective scoring based on displaying of anatomical structures,thymoma lesions,image artifacts and overall diagnosis confidence were performed,so did objective evaluation according to image signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of 2 kinds of images.The apparent diffusion coefficient(ADC)obtained with DWI were compared between groups.Receiver operating characteristic(ROC)curve was drawn,and area under the curve(AUC)was calculated to analyze the efficacy of ADC for differentiating low-risk and high-risk thymoma.Results Subjective scores of displaying anatomical structures,thymoma lesions,image artifacts and overall diagnosis confidence of ZOOMit were all superior to those of SSEPI(all P＜0.001),while SNR and CNR of ZOOMit were both higher than those of SSEPI(all P＜0.001).There were statistical differences of ADCSSEPI and ADCZOOMit between groups(both P＜0.001).The AUC of ADCssEPI and ADCZOOMit for distinguishing low-risk and high-risk thymoma was 0.865 and 0.922,respectively,of the former was higher than of the latter(Z=2.091,P=0.037).Conclusion rFOV DWI could be used to differentiate low-risk and high-risk thymoma.