Full-field digital mammography is well-established as one of the main diagnostic tools in patients presented with variable breast symptoms especially those presented with clinically palpable breast lumps, yet its sensitivity and specificity are considerably lower in patients with dense breasts. Our study reported the diagnostic sensitivity, specificity, PPV, NPV, and accuracy of FFDM in lesion characterization as 56%, 66.6%, 75%, 46%, and 60%, respectively.
On the other side, CESM is not affected by the breast density as only the enhancing masses will stand out while the rest of the glandular element is represented by background parenchymal enhancement. Our study reported the diagnostic sensitivity, specificity, PPV, NPV, and accuracy of CESM in lesion characterization as 100%, 63.6%, 77.8%, 100%, and 84%, respectively.
Our results were consistent in terms of the high sensitivity of CESM with two studies published in 2020 done by Qin et al. and Zhongflei et al., both studies were concerned with symptomatic patients with dense breasts and reported sensitivity of CESM ranging between 82.4% and 93.8% compared to 100% in our study. Also in another study done by Travesion-Aja et al. in 2019 which is considered one of the largest studies comparing CESM to FFDM in 465 patients with 644 lesions concluded that CESM significantly increased sensitivity compared to FFDM (from 82.5 to 92.3%) while in our study, CESM increased sensitivity from 56 to 100% [7,8,9].
The specificity of CESM calculated from our study (63.6%) is lower than the one calculated from other studies done in 2020 by Qin et al. and Zhongflei et al. where it was reported as 96.4% and 88.1%, respectively; this low specificity in our study is likely attributed to the small sample size (25 patients) compared to a large sample size in these studies which exceeded 100 patients [7, 8].
Moreover, our results are consistent in terms of the high sensitivity and low specificity of CESM with the systematic review and meta-analysis study done in 2016 by Tagliafico, et al. which analyzed 604 studies concluding that CESM has high sensitivity (96–100%) but low specificity (38–77%), also Luczyńska et al. (2016) concluded low specificity of CESM (27% in a study population of 115 patients) [10, 11].
In order to assess the added value of CESM numerically, CESM was assessed from two aspects; the ability to detect lesions that may have been missed by FFDM due to superimposed heterogeneously dense parenchyma hindering proper visualization of the lesion, and the other aspect was the characterization of lesions as benign or malignant.
In our study, CESM detected the target lesions in twenty-two cases out of twenty-five (88%). All the lesions detected by CESM were enhancing lesions; eight benign lesions and fourteen malignant lesions. On the other hand, FFDM detected multifocality or multicentricity in malignancy as well as multiple fibroadenomas in only 20% of the patients, the remaining lesions were identified only by CESM.
Regarding the three cases with clinically palpable lumps that were not detected by CESM as they did not enhance and proved to be benign by histopathology, this point was considered as an advantage for CESM rather than a pitfall; in other words, in these cases, the absence of enhancement was a sign of benignity. The lesions were diagnosed by histopathology and targeted ultrasound as one case of condensed glandular tissue, one case of fibroadenosis, and one case of fibrocystic disease.
CESM correctly characterized 21 cases (84%) as having benign or malignant lesions in concordance with the final histopathological results. It misdiagnosed only four cases (12%); those patients were two cases of lobular mastitis, one case of diabetic mastopathy and one case of fibroadenoma. Misdiagnosis was likely attributed to false upstaging non-mass enhancement to BIRADS 4, although the underlying lesions were chronic inflammatory condition or benign fibroepithelial lesion.
This high capability of CESM to detect all lesions and correctly characterize them as benign or malignant was studied by Xing et al. (2019); in a study population of 263 patients with 259 lesions, CESM detected 98.5% of lesions and correctly characterized or diagnosed 91% of lesions; the lesions that were not detected by CESM were two lesions of fibroadenoma, one lesion of breast adenosis with ductal dilation, and one lesion of breast adenosis with fibroma formation trend [12].
CESM has a significant role in determining the most appropriate treatment plan specially in cases with histopathologically proven breast cancer where a multifocal or a multicentric malignancy may alter the surgical decision (Figs. 3 and 4); this was observed in 57% out of fourteen cases diagnosed with breast cancer in agreement with a study done in 2016 by Ali-Mucheru et al. included 100 patients with pathologically proven breast cancer where CESM altered the surgical management to a more extensive surgery in 20% of these cases [13].
CESM is currently used for the detection of primary breast cancer, the assessment of the extent of disease, a problem-solving tool, and a replacement for MRI where the latter is contraindicated. In terms of patient preferences and tolerance, significantly higher overall preference towards CESM has been demonstrated, due to faster procedure time, greater comfort, and significantly lower rate of anxiety [14].
Concerning the future implications of CESM, preliminary data for the use of CESM in the screening of dense breasts are promising. Mammography is currently the only examination which has been demonstrated to reduce breast cancer mortality, as with all potential screening studies, it is critical to evaluate not only the improvement in sensitivity when using CESM but also if that improvement in sensitivity translates into a decreased number of interval cancers and increases mortality reduction over that of mammography [15].
The key limitation of our study was the small sample size as well as the common limitations of CESM in general which include lack of biopsy capability; if a finding is seen on recombined images only, it can be sampled by finding either a low energy correlates to target with stereotactic/tomosynthesis-guided core biopsy or an ultrasound correlates to target for ultrasound-guided biopsy. Another limitation relates to the field-of-view of a CESM. Similar to conventional mammography, areas along the chest wall, far medial breast, or in the axilla may not be well-imaged and may be a cause for a false-negative study. Recognizing these limitations is vital, especially if performing CESM in a patient with a palpable abnormality in one of these locations. In these cases, breast MRI may provide a more complete assessment [16].
Our study has deduced that CESM has a great capability to detect and characterize the clinically palpable masses and associated lesions that may be impalpable by clinical examination and missed by FFDM due to obscuration done by heterogeneously dense breast parenchyma, with a significant impact on the choice of the most appropriate treatment plan.