Differentiation of benign and malignant breast lesions by apparent diffusion coefficient value in mass and non-mass lesions

Background: Diffusion-weighted imaging (DWI) is one of methods in evaluation of breast lesions. We aimed to investigate the apparent diffusion coefficient (ADC) values in breast tumors and their accuracy in differentiating benign versus malignant lesions. Methods: In this cross-sectional study, 72 patients with 88 breast lesions were investigated by 1.5-T breast MRI from 2015 to 2017 in Athari Imaging Center in Tehran, Iran. Nearly all patients has undergone histopathology evaluation. One small region of interest (ROI) were placed on the most restricted region inside the solid part on the ADC map. Care was taken to avoid cystic or necrotic, fatty regions and hematoma inside the mass. A large round ROIs were placed in healthy fibroglandular tissue of contralateral breast ADC values were measured and compared in normal breast tissue and in most restricted parts of breast lesions (mass and non-mass). After determining cut-off for differentiation of benign and malignant lesions, sensitivity, specificity, accuracy, positive predictive value and negative predictive value were calculated. Results: Mean age of patients was 43.3 years. The average tumor size of benign and malignant lesions were calculated 26.0 mm, 35.3 mm respectively and 23 mm and 46 mm in mass and non-mass respectively. Invasive ductal carcinoma include the majority of pathology result (in 37.5% of the patients). Our results revealed that the measured ADC values in normal breast tissue were higher than breast lesions (P≤0.01). Mean ADC value in benign lesions was 1.40×10-3 mm²/s and for malignant lesion was 1.08×10-3 mm²/s. ADC value in the normal breast tissue was 1.79×10-3 mm2/s and was significantly higher than ADC value of breast lesions (benign and malignant). Cut-off value in non-mass was not valid, but in mass was 1.19×10-3 mm²/s with sensitivity, specificity, positive predictive value, negative predictive and accuracy of 89.7%, 83.8%, 87.5%, 86.6%, and 87.1% respectively. Conclusion: In DWI imaging, ADC value can differentiate benign and malignant masses with high sensitivity and specificity but not helpful in non-mass lesions.