This study investigated the i-maps of 858 operable breast cancers derived from ceDECT, focusing on IC and visual patterns, to detect and evaluate various subtypes of breast cancer. The i-maps produced sharp and obscure patterns depending on the visibility of the tumor, and the ICs of tumors were associated with the histological subtype and some malignant features of breast cancer; therefore, these indicators may be valuable, especially for surgeons, radiologists, and pathologists engaged in the diagnosis and treatment of breast cancer.
Few studies have evaluated the utility of ceDECT in breast cancer. Wang et al. reported associations between DECT parameters and immunohistochemical biomarkers of invasive breast cancer [21]. Volterrani et al. reported the feasibility of evaluating loco-regional staging by DECT in breast cancer [22]. Zhang et al. reported the efficacy of DECT for detecting lymph node metastases in preoperative breast cancer [23]. Our retrospective evaluation of i-maps in breast cancer confirmed that DCIS, an ER+/luminal A-like subtype with a low risk of malignancy, correlated with a high IC and displayed a sharp pattern; in contrast, the TN/HER2 subtype, which is associated with a high risk of malignancy, and special types like LC correlated with low ICs and showed obscure patterns. Furthermore, small-size cancers with DCIS, an ER+/luminal-A like subtype, and invasive breast tumors with a low risk of malignancy were highly detectable on i-maps, with high ICs and sharp patterns. In contrast, some special histological types (such as LC and MC), the TN and HER2 + subtypes, and some highly malignant cancers were obscure on i-maps, with a low IC or obscure pattern; therefore, the number of patients with these types of malignancies was underestimated by i-map before partial breast resection. We speculate that the difference in IC between various breast cancer subtypes depends on several factors, including tumoral cellular density, fibrosis, sclerosis, necrosis, and tumor vascularization.
I-maps may be useful in breast cancer patients because, during ceDECT, the patient lies in the supine position, which is the same position used during surgery; therefore, an i-map could be advantageous for the surgeon to estimate tumor location and breast thickness. In contrast, the main contraindication of ceDECT is allergy to contrast medium.
MRM is a very valuable technique that is especially useful in patients undergoing conservative breast surgery to determine the proper surgical margins. Dynamic contrast MRM is remarkable in facilitating the detection of the intraductal spread of breast cancer [24, 31]. Previous studies indicated that parameters derived from MRM were associated with histological subtype and prognosis, including treatment response to chemotherapy [32–34]. However, dynamic contrast MRM has its disadvantages. First, MRM depends on the menstrual cycle in premenopausal women, so it may potentially overestimate the tumor extent. Second, MRM is contraindicated in patients with internal metals or claustrophobia. We found that some special histological types (such as LC and MC), the TN and HER2 + subtypes, and some highly malignant cancers were obscure on i-maps derived from ceDECT with a low IC or obscure pattern, and the proper surgical margin was therefore difficult to evaluate. Our results suggest that tumors with a low IC and low visibility on the i-map of ceDECT scans require MRM before breast-conserving surgery. We cannot make any conclusions regarding the superiority of i-map or MRM. Our results indicate that i-maps may prevent overestimation by MRM for some histological or pathological features. An appropriate knowledge of the use of i-maps to perform appropriate resections with safe margins is variable among surgeons.
F-fluorodeoxyglucose-positron emission tomography (FDG-PET) and breast-specific PET scans are promising modalities for breast cancer [18]. Previous studies reported excellent detection of breast cancer, with parameters derived from FDG-PET being associated with the histological subtype and prognosis, including treatment response to chemotherapy [35–37]. Disadvantages of FDG-PET are as follows: higher radiation dose, higher cost than conventional CT, and the contraindication of diabetes.
Despite the findings of this study, it has several limitations. First, this study is single institute retrospective analysis. Second, our findings cannot elucidate the mechanism underlying variation IC and visual pattern in the tumor microenvironment. Our findings may be linked to other studies evaluating DECT for patients with breast cancer to build on their significance.
We argue that ceDECT is not a complete substitute for MRM or FDG-PET, but understanding the differences between these diagnostic tools can lead to a more accurate diagnosis in patients with breast cancer, as the pathological and physical characteristics of patients affect breast cancer visualization.
Our study has several limitations. First, this was a single-institution retrospective study. Second, the reasons for the different IC and visual patterns among tumors are unknown.