Objective: To determine the diagnostic accuracy of Diffusion Weighted Magnetic Resonance Imaging/Apparent and Diffusion Coefficient (DWI/ADC sequences) in malignant breast lesions taking histopathology as gold standard.
Study Design: Cross-sectional validation study.
Place and Duration of Study: Combined Military Hospitals Quetta & Peshawar, from Sep 2013 to Mar 2015 and Armed Forces Institute of Radiology and Imaging Rawalpindi, from Apr 2015 to Dec 2015.
Material and Methods: After informed consent, patients scheduled for biopsy of a suspicious breast lesion on sonomammography and/or mammography (BIRADS IV & V), fulfilling the inclusion criteria were evaluated with breast MRI including Diffusion Weighted Imaging (DWI) sequence using b-values of 0 & 750 mm2/sec. Apparent Diffusion Coefficient (ADC) values for the breast lesions were also calculated. MRI findings were correlated with histopathological results.
Results: A total of 299 cases were included in the study. Mean age of the study population was 45.73 years (SD ± 15.02) with a range of 18 to 89 years. On histopathology 77.9% (n=233) lesions turned to be malignant and 22.1% (n=66) were benign. On DWI 73% (n=219) lesions showed restricted diffusion and were labeled malignant while 27% (n=80) lesions showed facilitated diffusion and were considered benign. The mean apparent diffusion coefficient value of the malignant breast lesions was significantly lower than that of the benign breast lesions
(p-value<0.001). The calculated sensitivity, specificity, positive predictive value and negative predictive values of DWI/ADC mapping in differentiating between malignant and benign lesions were 92.2%, 93.9%, 98.1% and 77.5% respectively. The diagnostic accuracy was found to be 92.6%.
Conclusion: DWI is a non-invasive diagnostic modality for diagnosing malignant breast lesions. It can be used to reduce the number of unnecessary biopsies and it may help in reaching a definite diagnosis in cases where a suspicious breast lesion cannot be biopsied because of its small size or unsuitable location.
Keywords : ADC, Breast, Cancer, DWI, MRI.