Two Different Methods of Region-of-Interest Placement for Differentiation of Benign and Malignant Breast Lesions by Apparent Diffusion Coefficient Value

Abstract

Purpose: We aimed to investigate the influence of different methods of region-of-interest (ROI) placement on<br />apparent diffusion coefficient (ADC) values in breast tumours and their accuracy in differentiating benign versus<br />malignant tumors in mass and nonmass lesions. Methods and Materials: In this prospective study, 79 patients with<br />98 breast lesions, from 2015 until 2017, were investigated by 1.5-T breast MRI. Histopathology evaluation were done<br />for all malignant lesions and most of the benign ones. ADC values were measured in normal breast tissue and by two<br />ways of ROI placement in the breast lesions (mass and non-mass): 1- ROI covering the whole lesion, 2- ROI in the<br />highest part (most restricted area) of the lesion in DWI images. The accuracy of these two approaches were compared.<br />Results: The age range was 17-68 years with mean age 43.3 ± 9.9 years. 49% of the lesions were benign and 51% of<br />tumors were malignant. Our results revealed that the measured ADC values in normal breast tissue were higher than<br />breast lesions (P≤0.01). Appropriate cut off determination in non-mass was not valid by both methods, but in mass in<br />the first way was 1.45×10 -³mm²/s and in the most restricted part was 1.16×10-³ mm²/s. ADC values differed significantly<br />between the two ways of ROI placement in mass lesions (P<.001). Most restricted part ADC showed the best diagnostic<br />performance in mass lesions with area under curve 0.88 versus 0.82. Conclusion: ROI placement has significant impact<br />on the meseaured ADC values of breast lesions and ROIs in most restricted parts were more accurate than whole-lesion<br />ROIs. Cut-off values differed significantly based on the methods of measurement.