The Diagnostic Value Of High Tesla Magnetic Resonance Imaging In Benign And Malignant Breast Disease Lesions

Background and purpose:The incidence of breast cancer is located at the top of the female tumor in the global.Every nine women,there is one person in a lifetime risk of breast cancer in the western developed countries.China was a low incidence of breast cancer national,but in recent years,the incidence of breast cancer showed an upward trend year after year, and the trend of younger,with changes in the reproductive patterns and lifestyle.The breast cancer seriously endangers the health and lives of women.Early diagnosis, early treatment is an important measure to reduce breast cancer mortality and improve 5-year survival rate of breast cancer patients.Imaging has a great value for early diagnosis,clinical stage and treatment of breast cancer.The purpose of this study was to evaluate the value of MRI rout-scanning, dynamic contract-enhanced MRI and diffusion-weighted imaging in distinguishing between benign and malignant breast lesions.Materials and methods:We analyzed seventy-two lesions from fifty-five patients in the first affiliated hospital of Zhengzhou University from May 2008 to February 2009,who were operated acquired with histopathological demonstration,of which thirty were malignant and forty-two were benign.53 females and 2 males,with the mean age was 44.5±10.9 years(range 21～67 years).The main clinical features were breast masses. Using Siemens Magnetom Trio Tim 3.0T magnetic resonance device and a proprietary phase array breast surface coil to check the bilateral and whole breast at the same time. All lesions were examined with MRI plain scan,diffusion-weighted imaging and dynamic contract-enhanced MRI.The sequences of MRI plain scan used were three-dimensional fast low angle shot spoiled gradient-echo sequence(FLASH-3D) T₁WI and Turbo inversion recovery(TIR) T₂WI.Diffusion-weighted imaging was done with the single shot SE-EPI sequence,b=0s/mm²,500s/mm²,1000s/mm²;slice thickness:4mm.Dynamic contrast-enhanced imaging was done with FLASH-3D, with fat-suppression,axial T₁WI.The sequence parameters were as follow:TR/TE: 4.23ms/1.57ms;slice thickness:0.9mm.The same sequence was used pre-contrast one time and post-contrast six times with no gap between each post-contrast sequence. The overall acquisition time was 7min and 23sec.There was 20sec interval between pre-contrast and post-contrast sequence.An intravenous bolus injection of gadolinium diethylene triaminepenta acetate(Gd-DTPA) was give at a standard single dose of 0.1mmol/kg and at a rate of 2.5ml/s.This was followed by a flush of 25ml of saline solution at the same rate.Injection of contrast agent and saline flush was performed using an automatic injector.The data of DWI and dynamic contrast-enhanced MRI were transfer to Leonardo work station.We measured apparent diffusion coefficient (ADC) map and time-signal intensity curve was gain by the ADC and Mean Curve software.The lesions were classified as malignant or benign according the ADC value, the type of time-signal intensity curve(TIC),early-phase enhancement rate,peak value,peak time,morphology features and indirect features.We calculated the enhancement rate 1 minute after ejection of Gd-DTPA(ΔSI).The validities of dynamic contrast-enhanced imaging,ADC,and combination of the two methods were evaluated.Select the slice that shows the largest diameter of the lesion which with the maximal enhancement,exclude any hemorrhage,necrotic,cystic or calcification.The same size region of interest(ROI) was selected on the other breast in the same slice. The images were reviewed by two radiologists at workstation. Results:72 lesions of 55 cases that had been proved by pathology include 30 malignant lesions and 42 benign lesions.25 lesions(23 cases,include 1 male breast cancer) were invasive ductal carcinoma,1 lesion was invasive lobular carcinoma,4 lesions(3 cases) were ductal carcinoma in situ.42 benign lesions(28 cases) include 21 fibroadenomas, 1 breast papilloma,4 cysts,6 chronic inflammatory,9 adenosis of breast and 1 breast proliferation of man.31.9 per cent lesions(23/49) can not be detected by MRI plain scanning,while combining of morphology features,the sensitivity is 86.7%,the specificity 66.7% and the accuracy is 75.0%for detection of breast cancer.28 benign lesions were round or lobulated,well-defined,homogenous enhancement.26 malignant lesions were irregular shape or burr,obscure border,inhomogeneous enhancement.DWI showed that 97.6%of benign lesions(41/42) and all malignant lesions.The average ADC values of malignant lesions were 1.257±0.279×10^-3 mm²/s and 1.021±0.192×10^-3 mm²/s.The average ADC value of benign lesions were 1.549±0.341×10^-3 mm²/s,1.397±0.216×10^-3 mm²/s.The average ADC value of normal tissue were 1.974±0.492×10^-3 mm²/s and 1.764±0.432×10^-3 mm²/s.There were statistic significances between benign and malignant lesions,benign lesions and normal tissues,malignant lesions and normal tissues(F=50.998,P＜0.001; F=84.646,P＜0.001).b=500 s/mm²,the threshold of ADC for diagnosis was 1.5×10^-3 mm²/s,the sensitivity of diagnosis is 86.7%,the specificity is 76.2%,the accuracy is 80.5%,72.2%positive predictive value and 88.9%negative predictive value.b=1000 s/mm²,the threshold of ADC for diagnosis was 1.2×10^-3 mm²/s,the sensitivity,specificity,accuracy of ADC were 80.0%,85.7%,83.3%,positive predictive value was 82.7%and negative predictive value was 85.7%.The difference of the early-phase enhancement rate between benign and malignant lesions was statistically significant(x²=6.73,P＜0.01).The early-phase enhancement rate≥80%as malignant,diagnostic sensitivity was 100%and specificity was 59.5%.Early enhancement ratio≥100%as malignant,the sensitivity was 93.3%and specificity was 73.8%.The difference of the peak value between benign and malignant lesions had no statistical significance(P=0.18).The peak time of 90.0 per cent malignant lesions were less than 3 minutes.The difference of the peak time between benign and malignant lesions was statistically significant(P＜0.001).The distribution of curve types for malignant lesions was washout 46.7%(14/30),biphasic 50.0%(15/30),and monophasic 3.3%(1/30).The distribution of curve types for malignant lesions was washout 4.7%(2/42),biphasic 16.7%(7/42),and monophasic 66.7%(28/42).The difference of the type of time-signal intensity curve between benign and malignant lesions was statistically significant(x²=11.84,P＜0.01).Diagnostic sensitivity was 96.7%,specificity was 78.6%and accuracy was 86.1%.Conclusion:The value of MRI plain scan in distinguishing between benign and malignant breast lesions is limited.The ADC value among breast cancer,benign lesions with normal breast tissue is different.The ADC values can be used to identify benign and malignant breast lesions.The average ADC values of tissues were increased in b= 500 s/mm² than b=1000 s/mm².b=500 s/mm² and b=1000 s/mm²,the threshold of ADC for diagnosis was 1.5×10^-3 mm²/s and 1.2×10^-3 mm²/s,there was a higher sensitivity,specificity,accuracy.Dynamic contrast-enhanced imaging has value to differentiate benign from malignant breast lesions.Combination of morphology, dynamic contrast-enhanced and DWI improve the diagnostic specificity,has great value to make a correct diagnose.