Full-field digital mammography is accused of having low sensitivity and specificity especially in the dense breast due to overlapping glandular tissue.
Both CE-MRI and CEM have the advantage of providing morphological and functional information as they depend on neovascularity and angiogenesis of lesions [2].
Dynamic contrast-enhanced MRI breast has been used in the assessment of indeterminate mammographic lesions for a long time [11]. The disadvantages of CE-MRI are mainly its relatively high cost, long examination time, limited availability compared to the availability of mammography machine, and non-visualization of calcification [12].
Contrast-enhanced mammography uses a dual-energy technique performed after contrast administration to identify and characterize lesions based on angiogenesis, as well as morphologic features and density [9]. Also, low-energy images of CEM could detect microcalcifications, architectural distortion, and non-enhancing lesions [12].
The main disadvantage in CEM is that it lacks kinematic information about tumor enhancement [13].
Our study revealed 17/21 (81%) out of the non-enhancing lesions were benign, while 4/21 (19%) were malignant; out of 150 enhancing lesions, 113/150 (75%) were malignant, while 37/150 (25%) were benign. These results are comparable to results of Kamal et al. [14] who found that no enhancement was noted in 66/211 lesions (31.3%): 60/66 (90.9%) benign and 6/66 (9.1%) malignant lesions, while enhancement was observed in 145/211 lesions (68.7%): 42/145 (29%) benign and 103/145 (71%) malignant lesions (p value ≤ 0.001) [14].
We found that out of 158 enhancing lesions, 120/158 (76%) were malignant, while 38/158 (24%) were benign, and thirteen non-enhancing lesions were benign so our results agree with that of Bennani-Baiti et. al. [15].
Our study revealed that DCE-MRI sensitivity and NPV were slightly yet significantly higher than that of CEM (p value 0.014 and 0.013, respectively). The overall accuracy of DCE-MRI was better than that of CESM; however, no statistically significant difference could be detected.
Our results were comparable with Fallenberg et al. that showed that DCE-MRI sensitivity was slightly but significantly superior to CESM (p value < 0.001) [13].
Yousef et al. [16] concluded that CEM and MRI were equal in the sensitivity; however, their study was conducted on twenty cases only [16].
Elfiky et al. [17] and Yasin and El Ghany [12] did a comparative study between CESM and CE MRI; they concluded that contrast-enhanced spectral mammography (CESM) showed slightly lower sensitivity (88.89%, 94.1%) than BMRI (96.30% and 100% respectively) [12, 17].
However, Łuczyńska et al. [18] found that diagnoses based on CESM are slightly more reliable than those based on breast MRI. The sensitivity of CESM examination was 100%, higher than the 93% sensitivity of breast MRI (p ≤ 0.04). The accuracy of the CESM exam (79%) was also higher than that of breast MRI (73%) in their study, but this difference was not statistically significant. NPV was 100% for CESM and only 65% for breast MRI (p < 0.001) [18].
The specificity of CE-MRI was slightly higher than that of CEM in our study but this was not a statistically significant difference. Fallenberg et al. [13] found that the specificity of CESM was better than that of MRI. This could be attributed to the difference in population between their study and our study as their study included only cases with pathologically proven index lesion, yet in our study we included sonomammography indeterminate lesions including both benign and malignant pathologies [13].
In another study done by Xing et al. [19], the sensitivity, PPV, and NPV of CEM were comparable to those of MRI. However, the specificity of CEM was higher than that of MRI [19].
Regarding the assessment of multiplicity in our study in reference to histopathology, CE-MRI was better than CEM in the detection of multiplicity.
Our results were comparable to Jochelson et al. that concluded that CESM had a lower sensitivity for depicting additional ipsilateral cancers than breast MRI [20].
However, Łuczyńska et al. found that CESM detected multifocal breast cancers in all cases studied [18]
Limitation of the study
The assessment in the study was limited by the absence of a standardized BIRADS lexicon for CEM examination; however, we applied the 2013 MRI BIRADS lexicon morphology descriptors. A standardized lexicon of morphology descriptors seen on CEM would provide the optimal analysis and reporting of enhancing lesions detected in the breast.