Signal intensity ratio and signal-to-noise ratio of breast lesions in 3.0 T MR diffusion weighted imaging with different b values

Abstract

Objective To investigate the signal intensity ratio and signal-to-noise ratio of breast lesions in 3.0 T MR diffusion weighted imaging with different b values.Methods Ninety seven patients with 106 solid breast lesions (44 malignant,62 benign) confirmed by pathology were retrospectively analyzed.The patients were examined by 3.0 T MR DWI with different b values (b =0,400,800,1 000 s/mm2) before surgery.The signal-to-noise ratio (SNR) and signal intensity ratio (SIR) of benign and malignant lesions were observed and measured under different b values.One-way ANOVA and t test were used to analyze quantitative data.ROC curve was used to analyze the diagnostic efficiency of SIR under different b values.Results Under different b values,class A image was found in 92 cases,class B images was found in 5 cases.While b value were 0,400,800,1 000 s/mm2,SIR of benign lesions were 2.33 ± 1.36,2.25 ± 1.13,2.06 ± 0.84,2.02 ± 0.79 respectively,SIR of malignant lesions were 2.02 ± 0.79,2.27 ± 0.85,2.61±0.78,2.82 ± 1.01 respectively.While b value was 0 or 400 s/mm2,there was no significant differences for SIR between benign and malignant lesions (t value were 1.58,1.26 respectively; P value were 0.12,0.90 respectively),but there were statistically significances between benign and malignant lesions under b value 800 s/mm2 or 1 000 s/mm2 (t value were 3.41,4.29 respectively ;P ＜0.01).There was no differences in SIR for benign and malignant lesions under different b values respectively (F value is 1.21,2.22 respectively; P ＞0.05).While b value were 0,400,800,1 000 s/mm2,the diagnostic sensitivity and specificity of SIR for breast benign and malignant lesions were 56.8％ (25/44),56.8％ (25/44),75.0％ (33/44),77.3％ (34/44) and 51.6％ (32/62),54.8％ (34/62),66.1％ (41/62),66.1％ (41/62) respectively.While b value were 0,400,800,1 000 s/mm2,SNR were 170 ±93,145 ±72,84 ±41,70 ± 39 respectively.Different b values,there was statistically significant difference between groups (F =55.89,P ＜ 0.01) ; and there were significant differences between every two b values (P ＜ 0.05).Conclusion The higher b values (800 s/mm2 and 1 000 s/mm2) are superior to lower b values in the differential diagnosis of benign and malignant breast lesions using 3.0 T MR scanner. Key words: Breast neoplasm; Diffusion magnetic resonance imaging; Comparative study