الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Breast MRI is a highly sensitive imaging tool for breast cancer detection and has gained clinical acceptance for a range of clinical indications, including supplemental screening for women at high risk of developing breast cancer and pre-operative evaluation of extent of newly diagnosed breast cancer. However, standard contrast-enhanced breast MRI used in general clinical practice provides low specificity, therefore, exposing many patients to unnecessary biopsies and limiting its clinical use and acceptance across institutions.(15) There is a direct correlation between DCE-MRI and tumor vascularity, but no evidence to link this technique with tumor cellularity. (125&129) More recently, diffusion weighted imaging (DWI) MRI and the resulting maps of apparent diffusion coefficient (ADC) have been evaluated as a complementary method to DCE-MRI. (130& 131) None of the available imaging methods employed today has succeeded in tracking the full ductal tree. Since most of mammary malignancies originate from the ductal epithelial cells, and initially spread within the ducts, the ability to monitor and track changes in microstructure of the mammary gland tissue and to identify malignant growth are highly significant. (120) Mapping the anisotropic water diffusion properties of the ducts can help meet this challenge. The utilization of this approach by diffusion tensor imaging (DTI) study may be able to detect breast cancer without the injection of a contrast agent. The aim of this study was to evaluate the diagnostic efficiency of the DTI for the discrimination of malignant from benign breast lesions. The correlation between DTI parameters were evaluated assuming the histo-pathologic diagnosis as a reference standard. Fifty female patients, aged from 25 - 75 years with a mean of 47.8 ± 14.6 years, were included in this prospective study. They were referred to MRI unit of the Radio-diagnosis and imaging department of Tanta University Hospital with breast complaints and /or abnormal sono-mammographic findings. All participants underwent MRI with diffusion weighted and diffusion tensor imaging, 45 of them were evaluated by dynamic contrast enhancement MRI. Histopathological examination of the breast lesions was done and the results were correlated with that of the imaging studies. Histopathological examination of breast lesions: - Malignant lesions were found in 24 (48%) of cases: 18 invasive ductal carcinoma, 2 invasive lobular carcinoma and 4 ductal carcinoma in situ. - Benign lesions were found in 26 (52%) cases: 7 fibroadenoma, 6 fibroadenosis, 4 adenoma, 3 intra ductal papilloma, 3 fat necrosis, 2 chronic granulomatous mastitis and one fibroadenolipoma. - Malignant lesions were found more in older aged patients (57.25 ±12.48 years) compared to that of benign lesions (39.23 ± 10.70 years). - Malignant breast lesions were more common in the nulliparous women (65 %) and in those with a positive family history of breast cancer (62%). Dynamic contrast enhancement (DCE): - Most of the homogenous enhancing mass pattern was in benign (13, 56.52%) cases in comparison to 4 malignant cases (18.18 %). - Most of the heterogenous enhancing mass and non-mass enhancement patterns were in malignant (18 cases, 82%), compared to benign lesions (8 cases, 35%). - Out of the 23 benign lesions, 20 (86.95 %) were with type 1 curve, while 21 of the 22 malignant lesions (95.4%) were with type II & III curves. - Sensitivity, specificity and diagnostic accuracy of DCE in differentiating malignant from benign lesions were 95.4%, 86.95% and 91.1%, respectively. Diffusion weighted and diffusion tensor MRI: - Mean apparent diffusion coefficient (ADC) values were significantly lower in malignant (1.054 ± 0.284 × 10−3 mm2/s) than in benign (1.388± 0.228 x 10−3 mm2/s) breast lesions. - Sensitivity, specificity and diagnostic accuracy values of DWI in differentiating malignant from benign lesions (with a cut - off value of 1.21 x 10−3 mm2/s) were 88.46%, 87.50 % and 86.7%, respectively. - Fractional anisotropy (FA) values were significantly higher in malignant (0.202 ± 0.065) than in benign (0.129 ± 0.033) lesions, with a cut- off value of 0.15. Sensitivity, specificity and accuracy were of 95.83%, 96.15% and 95.6%, respectively. - Relative anisotropy (RA) values were significantly higher in malignant (0.180 ± 0.068) than in benign (0.117 ± 0.034) lesions, with a cut- off value of 0.13. Sensitivity, specificity and accuracy were 91.69 %, 92.31 % and 90.2% respectively. - Values of λ1 were significantly lower in malignant (1.4± 0.45× 10−3 mm2/s ) than in benign (2.19 ± 0.659 x10−3 mm2/s) lesions, with a cutoff value of 1.71 x10−3 mm2/s. Sensitivity and specificity were 95.83 % and 96.15%, respectively. - Values of λ2 and λ3 were significantly lower in malignant than in benign lesions. Mean values of λ2 and λ3 in benign lesions were 1.477 ± 0.377 and 1.461± 0.410 x 10−3 mm2/s, respectively and in malignant were 1.157 ±0.249 and 1.034±0.274 x 10−3 mm2/s, respectively. - Cut -off value of λ2 was 1.31 x 10−3 mm2/s with a sensitivity of 87.50 % and a specificity of 84.62%. - Cut -off value of λ 3 was 1.19 x 10−3 mm2/s, with a sensitivity of 90.67% and a specificity of 89 %. - Values of λ1- λ3 were significantly lower in malignant (0.545 ± 0.133× 10−3 mm2/s) than in benign (0.745±0.102× 10−3 mm2/s) lesions with a cut -off value of 0.65 x 10−3 mm2/s. Sensitivity and specificity were 95.83 % and 96.15%, respectively. - Mean diffusivity (MD) values were significantly lower in malignant (1.232 ± 0.442 × 10−3 mm2/s) than in benign (1.671 ± 0.459 × 10−3 mm2/s) lesions, with a cut -off value of 1.41 x 10−3 mm2/s. Sensitivity, specificity and accuracy were 91.6 %, 92.3 % and 91.4%, respectively. Diagnostic performance of DTI in the differentiation of malignant and benign lesions and comparison with DCE: - Malignant lesions were significantly associated with higher values of fractional and relative anisotropy and with lower values of all other DTI parameters (ADC, λ1, λ2, λ3, λ1- λ 3 and MD). - Type II and III curves were associated with higher values of fractional and relative anisotropy and with lower values of all other DTI parameters. Comparison of the diagnostic performance of DTI and DCE Amongst DTI parameters, λ1, λ1-λ3 and FA showed the highest diagnostic accuracy: sensitivity (95.83%) and specificity (96.15%). Following, DCE: sensitivity and specificity were 86.95 % and 95.4 %, respectively and lastly MD with specificity and sensitivity of 91.67% and 92.31%, respectively. Evaluation of diagnostic performance of combined DTI Parameters and DCE-MRI: The sensitivity of DCE-MRI measurement and DTI measurements in 45 patients (who evaluated by DCE-MRI) is the same, each alone is 95.4%, while the specificity of DTI was higher (95.6 %) than that of DCE-MRI (86.9%). The combined evaluation by DCE and DTI values increased the sensitivity to 100%, and specificity of DCE to 95.6%.