Diffusion Weighted MRI Of Breast AT 3.0T: To Determine The Best B Value For Diagnostic Efficiency Of Signal Intensity Ratio And Signal Noise Ratio Of Breast Lesion With Different B Values

Objectives:Our purpose of this study is to determine the best b value for diagnostic efficiency of Signal Intensity Ratio and Signal to Noise Ratio between benign and malignant breast lesion with different b values.Methods:This study included 201 female patients with 205 breast lesions (94 were benign, 111 were malignant breast tumors) as the clinical cases which were confirmed by histopathology prior to surgery and DW-MRI at 3.0T with six different b values (b=0,400, 800,1000,1200,1600s/mm2) in our university affiliated hospital from March 2011 to Nov 2014. The background noise, signal intensity of breast lesion and signal intensity of normal breast parenchyma were measured for each of the b values at the workstation by using a fixed size ROIs for each of the b values. We calculated SNR (Signal to Noise Ratio) and SIR (Signal Intensity Ratio) for the entire benign and malignant breast lesion for each of the b value using formula:SNR= SI breast lesion/Noise, SIR= (SI breast lesion-SI normal breast parenchyma)/SI normal breast. All the quantitative data were analyzed using independent sample t-test and ROC curve for the diagnostic efficiency of Signal Intensity Ratio for each of the b values separately using IBM SPSS 21.0 software package to calculate the Sensitivity, Specificity, Positive predictive value, Negative predictive value and Accuracy Rate with each of their cutoff value.Results:1. While comparing SIR and SNR with different b values the result shows that With increase b value, Signal to Noise Ratio decreases and Signal Intensity Ratio increases between all the six b values used in our study for both benign and malignant breast lesion.2. The mean SIR for malignant lesion was higher than the mean SIR for benign breast lesion among all the six b values and SIR was statistically significant for b 800,1000, 1200,1600s/mm2 (p<0.05).3. SIR diagnostic efficiency for benign and malignant lesion for bO and b400s/mm2 was not significant as (p> 0.05), but for b=800, b=1000, b=1200, b=1600s/mm2 was statistically significance (p< 0.05) with Sensitivity 59.6%,61.9%,71%,71%, Specificity 62.2%,58.1%,73.5%,69.4%, Positive Predictive value were 63.88%,60%, 80%,79.06%; Negative Predictive value were 56.7%,60%,62.85%,59.45% and accuracy were 60.48%,60%,72.5%,70% respectively for b=800,1000,1200,1600s/mm2 respectively. Among all the six b value, b1200s/mm2 has the highest sensitivity (71%), specificity (73.5%), PPV (80%), NPV (62.85%) and best accuracy rate (72.5%) with cut off value at 2.30 in differentiating benign and malignant breast lesions.4. There was significance for all b values except for b=0 and b=400 using SNR.Conclusion:The higher b values b1200s/mm2 is much better than other b values in differentiating benign and malignant breast lesion at 3.0T DW-MRI with optimum SIR and SNR. The b=1200s/mm2 having highest Sensitivity (71%), Specificity (73.5%), PPV (80%), NPV (62.85%) and best accuracy rate (72.5%) for using Signal Intensity Ratio among other b values used in our study...