In 3.0 T Mr Diffusion Weighted Imaging (dwi) Can Parameter Selection And Clinical Application In Breast Imaging

PartⅠComparison of diffusion-weighted images using different fat suppression sequences at 3.0T MRI of the breastObjective:To compare the image quality in normal breast DWI using four different fat suppression sequences so as to select the optimal fat suppression at 3.0T MRI.Materials and methods:Diffusion-weighted breast images using four different fat suppression sequences (water excitation, Fatsat, IR, and Fatsat+IR) were obtained in 44 females at 3. OT MRI (Magnetom Verio, Siemens). Image quality of each group was evaluated and scored by five points (score 1-5):very poor, poor, moderate, good and excellent. Image quality score and signal-to-noise ratio (SNR) with different fat suppression sequences at the same b value of 0,1000s/mm2 were compared and analyzed.Results:Average score of the image quality of the breast DWI with water excitation was 3.07±0.79. There were 34 cases with subjective quality score reaching 3 and above(diagnostic), accounting for 77.27% of the total cases. Average score of the image quality with Fatsat was 2.43±0.82. There were 20 cases with subjective quality score reaching 3 and above, accounting for 45.45%. Average score with IR was 1.32±0.60. There were 3 cases with subjective quality score reaching 3 and above, accounting for 6.82%. Average score with Fatsat+IR was 2.07±0.99. There were 15 cases with subjective quality score reaching 3 and above, accounting for 34.09%. The difference among the four different fat suppressions was statistically significant (P=0.0001<0.01). Higher image quality score of the breast was obtained in the group using water excitation than those using the other three fat suppression sequences, and the differences were statistically significant (P=0.0002,0.000, 0.000). Average SNR of the breast DWI with water excitation was 52.28±19.34, and those of the other three groups were 39.93±15.07,23.00±7.34 and 23.00±7.34. The difference among the four different fat suppressions was statistically significant (F=90.73, P=0.0000<0.01). Higher SNR of the breast was obtained in the group using water excitation than the other three groups, and the differences were statistically significant (P values were all 0.000).Conclusion:DWI using water excitation is helpful for improving image quality and SNR at 3. OT MRI of the breast.PartⅡIntraindividual comparison of diffusion-weighted imaging at 3.0 T and 1.5T MRI of the normal breastObjective:To compare the image quality of normal breast DWI at 3.0T and 1.5T MRI so as to evaluate the feasibility of DWI at 3.0T MRI of the breast. Materials and methods:Forty-four female underwent DWI of the breast both at 3.0T MRI (Magnetom Verio, Siemens) and at 1.5T MRI (Magnetom Avanto, Siemens). DWI was performed using water excitation at 3.0T MRI and using Fatsat at 1.5T MRI with the same b value of 0, 1000s/mm2. Subjective image quality was scored by five points (score 1～5):very poor, poor, moderate, good and excellent. Image quality score, signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) with different magnetic field strength were compared and analyzed.Results:Average score of the image quality at 3.0T was 3.07±0.79. There were 34 cases with subjective quality score reaching 3 and above(diagnostic), accounting for 77.27% of the total cases. Average score of the image quality at 1.5T MR was 3.23±0.52. There were 42 cases with subjective quality score reaching 3 and above (diagnostic), accounting for 95.45%. Slightly lower image quality score was obtained at 3.0T than at 1.5T DWI, however the difference was not statistically significant (P=0.1615>0.05). Average SNR of the breast DWI was 52.28±19.34 at 3.0T, and 49.97±17.99 at 1.5T. Slightly higher SNR value of the breast was obtained at 3.0T than at 1.5T, whose the difference not statistically significant (P=0.5500>0.05). Average ADC value of the breast DWI was 1.80±0.44×10-3mm2/s at 3.0T, and 1.73±0.32×10-3mm2/s at 1.5T. The difference between them was not statistically significant (P=0.0652>0.05).Conclusion:DWI can be used at 3.0T with the image quality and the ADC value nearly equivalent to 1.5T.PartⅢValue of diffusion-weighted MR with different b values in the diagnosis of breast lesions at 3.0TObjective:To evaluate the value of diffusion-weighted MRI with different b values in the diagnosis of breast lesions at 3.0T.Materials and methods:Twenty normal and 31 patients with 17 benign breast lesions and 15 malignant ones underwent diffusion-weighted imaging at 3. OT MRI (Magnetom Verio, Siemens) with different b values of 0,750,1000,1250s/mm2. The other conventional sequences (T2WI and T1WI dynamic contrast-enhanced MRI) were performed at 3.0T MRI or at 1.5T MRI (Magnetom Avanto, Siemens). Subjective image quality was scored by five points (score 1-5):very poor, poor, moderate, good and excellent. Image quality score, contrast-to-noise ratio (CNR) and apparent diffusion coefficient (ADC) of normal breast, benign lesions and malignant ones with the same b value and different b values were compared and analyzed. Sensitivity, specificity and accuracy for diagnosis of breast cancer were calculated respectively with different b values, as well as the ROC curves.Results:(1) Average score of the image quality was 3.29±0.78 when b value was 750s/mm2. There were 41 cases with subjective quality score reaching 3 and above (diagnostic), accounting for 80.39% of the total cases. Average score of the image quality was 3.10±0.90 when b value was1000s/mm2. There were 37 cases with subjective quality score reaching 3 and above, accounting for 72.55%. Average score of the image quality was 2.88±0.93 when b value was 1250s/mm2. There were 32 cases with subjective quality score reaching 3 and above, accounting for 62.75%. The difference among the different b values was not statistically significant (P=0.0618>0.05). (2) Average CNR of the breast DWI was 173.90±71.05 when b value was 750s/mm2. Average CNR was 121.11±47.86 when b value was 1000s/mm2. Average CNR was 104.88±58.56 when b value was 1250s/mm2. The difference among the different b values was statistically significant (F=11.97, P=0.0000 <0.01). Higher CNR was obtained when b value was 750s/mm2 than those when b value was 1000s/mm2 and 1250s/mm2, and the differences were statistically significant (P values were 0.002 and 0.000), but the difference between the b value of 1000s/mm2 and 1250s/mm2was not statistically significant (P=0.822>0.05). (3)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 b value. Among them the differences were statistically significant (P values were all 0.000). The difference between normal breast and benign lesions was statistically significant (P<0.05), and the difference between benign and malignant lesions was statistically significant (P<0.01). With b value increased, ADC value was found reduced in all three groups, and the difference among them was no statistically significant (P>0.05). (4) The cutoff of ADC value was 1.35×10-3mm2 1.28×10-3mm2/s, and 1.18×10-3mm2/s when b value was 0,750s/mm2 0,1000 and 0,1250s/mm2. Sensitivity, specificity and accuracy for diagnosis of breast cancer was 80%,89.19%,86.54%; 80%,1.08%,80.77% and 80%,83.78%,82.69% respectively. And the area under ROC curve (AUC) was 0.8875,0.8667 and 0.8829 respectively. The difference among them was not statistically significant (P>0.05).Conclusion:(1) Better image quality and CNR score were obtained when b value was 0,750s/mm2 than those when b value was 1000s/mm2 and 1250s/mm2 at 3.0T diffusion-weighted MRI. (2)Diagnosis of breast benign and malignant lesions with diffusion-weighted MRI must be made in combination with ADC value. (3)Accuracy in the detection of breast cancer at 3.0T diffusion-weighted MRI was high with all b values (0,750; 0,1000 and 0, 1250). However we believe the best b value was 0,750s/mm2 because of its highest image quality and CNR.