Nowadays, MRI of the breast has become an important investigation for breast focal lesions characterization. Many researches described this importance in practice [7].
Our study included 60 patients, with mean age of 49 years (their ages ranged between 37 and 61 years old). This is consistent with El-Wakeel et al.’s study as the ages of the patients included in his study ranged between 30 and 65 years. The age of patients was younger in cases with benign lesions and ranged between 30 and 55 years with a mean age of 40.2 years. The age of patients was older in cases with malignant lesions, ranging between 35 and 62 years with a mean age of 48.4 years. So the incidence of malignant lesions was increased with increased age [8].
Differences in ADC were most dramatic in large, heterogeneous, and non-mass lesions. Some studies have reported that a smaller ROI placed over the most hypointense ADC area may provide better discriminating performance by reflecting the worst pathology within a heterogeneous lesion. On the other hand, whole tumor measurement may allow better reproducibility. Semi-automated ROI selection techniques further show promise to improve efficiency, accuracy, and reproducibility of breast lesion ADC measures [9].
Researches or studies were done for this subject had reported that the mean ADC values of malignant lesions (range 0.95–1.22) were significantly different from benign lesions (1.44–1.67) depending on the b value [10].
Regarding our study, ADC values of the solid breast lesions were moderately higher than those recorded in the literature. That may be due to usage of lower b value in our protocol (b values 0–800 mm/s2), while that of the other most studies was (0–1000), this was due to the need to obtain a high signal-to-noise ratio even with a four-channel coil.
The ADC values of malignant lesions (1.01–1.51; mean 1.29) and that of benign lesions (1.32–2.02; mean 1.67) were highly significant differences (P < 0.001). Also, significant differences in diffusion coefficient between malignant lesions and normal breast tissue were reported (mean ADC was approximately 2 in normal breast) [11]. In our study, we did not do this evaluation because we were interested only with solid masses which did not show any normal breast tissue in their histopathology. However, relatively few reports related to our subject found that the possible cause of false-negative results was low cellularity of some histopathological types such as mucinous, lobular, apocrine, and scirrhous carcinomas [12].
While false-positive DWI findings were found in some of the benign focal lesions such as fibrocystic mastopathy and intraductal papilloma that is mainly due to higher cellularity of these lesions, fibrocystic mastopathy showed the lowest ADC values (1.45) were recorded for a case in previous studies [13].
In our report, we were unable to perform a valuable statistical evaluation of the possible correlation between ADC and histopathology due to the small number of patients and the qualitative distribution of malignant lesions. This correlation had been supported by some authors (Nasu et al., 2008) but refused by others [14].
On the other hand, our study had some limitations, because we selected only patients with hepatic diseases who had solid lesions deserving investigation with breast MRI, and only those requiring pathological characterization. Our series did not contain findings with a low index of suspicion, the presence of which might have reduced the diagnostic performance of DWI.