الفهرس 
Introduction and aim of the work
IntroductionOnly 14 pages are availabe for public view
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Abstract
Breast asymmetry is not a very specific finding, as it may be due to normal hormonal variation of the parenchymal pattern, summation artifact or may indicate a true pathology.
The aim of this study is to identify the role of DWI in the assessment of asymmetric breast densities identified on mammograms, and to assess the various benign and malignant causes of various types of asymmetries.
Fifty female patients were enrolled in this prospective study during the period from April 2016 to January 2019.
All patients were presented with asymmetric density during either screening or diagnostic mammography.
All patients underwent DCE-MRI and DWI. Based on the BIRADS lexicon 5th edition, the findings were interpreted and classified for each lesion based on a combination of morphologic and kinetic criteria and ADC values. All findings were correlated with histopathological results.
Dynamic contrast enhanced MRI had sensitivity 100% , specificity 74.3%, Positive predictive value 62.5%, negative predictive value 100%, and accuracy 82%.
Diffusion weighted imaging showed that the best ADC cut-off value to differentiate between benign and malignant lesions was 1.10 x10-3 mm2/s; with sensitivity 80%, specificity 88.6%, positive predictive value 75%, negative predictive value 91%, and accuracy 86%. The mean ADC value for benign lesions was 1.59 ± 0.4 x10-3 mm2/s, and for malignant lesions was 0.82 ± 0.3 x10-3 mm2/s. Best results can be achieved by implementation of the combined DCE-MRI and DWI protocol, with sensitivity 93.3%, specificity 94.3%, positive predictive value 87.5%, negative predictive value 97.1%, and accuracy 94%.Conclusion Breast asymmetry is a potentially perplexing finding caused by a spectrum of normal variations and different pathologies. The clinical significance of breast asymmetries is that it may indicate an underlying malignancy. Special concern is applied to asymmetries associated with other suspicious mammographic findings or a clinically depicted mass. Mammography allows good detection, localization and preliminary BIRADS classification of the underlying pathology of breast asymmetry. However, it has a limited sensitivity and specificity for cancer detection. MRI can be used as a problem solving method that provides better characterization and allows more feasible BIRADS assessment. DCE-MRI is the most sensitive method for detection of breast cancer and considered the cornerstone of breast MRI imaging protocol. However, it provides a limited specificity that may increase the unnecessary invasive procedures. Combination of DCE-MRI with DWI as a functional imaging procedure provides both qualitative and quantitative assessment, and allows more characterization of breast lesions, thus permitting a more confident management. The best specificity and accuracy can be achieved by the combined protocol of DCE-MRI and DWI. DWI was useful adjunctive measure that maintained the high sensitivity, increased specificity and maximized the overall diagnostic accuracy of breast MRI examination. However, DWI cannot be used as a stand-alone procedure for assessment of breast asymmetric density. Sensitivity decreased due to false negative results associated with higher ADC values atypical ductal hyperplasia/DCIS and specificity decreased due to false positive results associated with lower ADC values in inflammatory lesions. We recommend further studies with larger sample size on the role of DWI in assessment of asymmetric findings frequently detected on screening programs. High cost, long examination time and the necessity of contrast administration has always been an obstacle for the use of breast MRI as a screening tool. DWI is ideal for this purpose, because it is a rapid sequence that can be used safely with pregnant patients and patients in whom contrast administration is contraindicated. However, DWI has low spatial resolution; anatomical and morphological guidance with other non-enhanced MRI sequence could overcome this limitation. We think that an abbreviated protocol (T1WI, T2WI, STIR, DWI and ADC map) might be suitable for screening as it decreases the acquisition and interpretation time. It may be cost effective, reassuring, and safe procedure that allows more confident decision of short term follow up for cases of one view asymmetry and other asymmetric densities attributed to normal hormonal variations, hormonal replacement therapy, focal fibroadenosis or subtle postoperative changes.