Objective: We aimed to investigate the morphological and quantitative characteristics of malign and benign breast masses in unenhanced sequences, and to determine the effects of unenhanced sequences on benign-malign lesion distinction and malignancy prediction.

Material and Method: We retrospectively analyzed the morphological features with unenhanced T1 weighted imaging (T1WI), and quantitative features with fat-suppressed T1WI, Turbo inversion recovery magnitude (TRIM) T2WI and Diffusion weighted imaging (DWI) of 51 benign and 45 malign breast lesions. Morphological characteristics of breast masses including their edges and shapes were evaluated. The lesion / fibroglandular tissue (FGT) intensity ratio and ADC values which are quantitative characteristics were measured by ROI. Between malign and benign lesions, Student-t test was used for comparison of quantitative values, whereas chisquare test was used for comparison of morphological features.

Results: There was a significant relationship between malign-benign condition and edge and shape features of lesions on the T1WI respectively (p <0,001, p =0,002). ADC values were significantly different between malign and benign ones (p <0,001). The mean ADC value was found to be 0.98 ± 0.27x10¯³ mm2/sec for malign lesions and 1.24 ± 0.34x10¯³ mm2/sec for benign lesions. The ADC cut-off value was determined to be 1.20x10¯³ mm2/sec. For ADC cut-off value, sensitivity, specificity, PPV, NPV and diagnostic accuracy were 88%, 60%, 66%, 85%, and 73%, respectively.

Conclusion: In the unenhanced MRI, DWI is the most important noncontrast imaging that we can quantitatively evaluate in the distinguishing malign and benign lesions. The evaluation of the lesion morphology on T1WI may be considered as a guide in the prediction of malignancy.