| Objective:To evaluate the application value of diffusion-weighted imaging with different b values in the diagnosis of breast lesions at3.0T magnetic resonance imaging (MRI) and meanwhile to confirm the optimal b value by which diffusion characteristics of tissue can be accurately reflected in order to improve diagnostic accuracy of Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) for the diagnosis of benign breast lesions and malignant ones.Methods:4cases of patient with breast masses by palpation went to our hospital for further examination and definite diagnosis and underwent conventional MR scanning and diffusion-weighted imaging from March,2012to January,2013. Images of normal glands of these patients were taken as control group. Diffusion-weighted imaging(DWI) and apparent diffusion coefficient ADC) were obtained through setting different value b of0,600s/mm2,800s/mm2,1000s/mm2and1200s/mm2. Respectively measured the apparent diffusion coefficient (ADC), signal noise ratio (SNR), contrast-to-noise ratio (CNR) and signal intensity ratio (SIR) of normal breast, benign lesions and malignant ones at diffusion-weighted images and apparent diffusion coefficient images with different b values. Compared and analyzed the apparent diffusion coefficient (ADC) among different b values in accordance of pathological diagnosis used as the gold standard. To evaluate the quality of images through the signal noise ratio (SNR), contrast-to-noise ration (CNR) and signal intensity ratio (SIR) of diffusion-weighted imaging and apparent diffusion coefficient (ADC). The ROC curves of the patients were also needed to be made for the study. A comparison of diagnostic efficiency with different b values on malignant breast lesion was make in order to determinate the optimal critical value of apparent diffusion coefficient(ADC) by which the malignant ones can be found accurately. Moreover, sensitivity and specificity of the diagnosis were analyzed as well.Results:Two analysis methods were used in the course of study. In accordance with Pearson correlation analysis method, ADC of benign lesion and malignant ones decreased as value b increasing (r=-0.923and-0.855, P<0.01)) within the scope of value b from600s/mm2to1200s/mm2as well as the SNR and CNR. However SIR showed an opposite effect and it increased along with value b increasing. In the one-way analysis of variance we found that average ADC value of normal breast was higher than benign lesion, while that of benign lesion was higher than that of malignant ones at the same value b (p values were all0.000). SNR, CNR and SIR of lesions were obviously higher than the other three groups when b value was800s/mm2(p<0.05) which created images with higher quality. Respectively made ROC curves for the benign lesions and malignant ones at four different b values and obtained the result that values of AUC of600,800and1000were0.875,0.905and0.914which showed AUC was the largest when value b was1000s/mm2. But the difference of AUC was not statistically significant when b values were800and1000(P=O.1295>0.05).Both of the diagnosis had equal high accuracy. In the combination of the quality of image, the accuracy of ADC for differential diagnosis of benign and malignant breast lesions was at the maximum when b was800s/mm2. The optimal cutoff ADC value was1.23×10-3mm2/s at the same time sensitivity and specificity were90.5%and85.7%and both were higher than the others at different b values. Conclusion:Image quality was higher when b value was800s/mm2that of the images at other b values at3.0T. Meanwhile, diagnostic efficiency of ADC for the diagnosis of benign lesion and malignant ones was obviously useful which was recommended to be applied into clinical diagnosis. Diagnosis of breast lesion with diffusion-weighted imaging must be in combination with ADC values. Both sensitivity and specificity were superior when the cutoff ADC value was1.23×10-3mm2/s. |
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