Abstract P1-02-12: Evaluating the usefulness of dual-energy computed tomography for the preoperative diagnosis of the extent of spread of breast cancer
Authors: Yamasawa Haruna , Murakami Akari , Takaoka Megumi , Kusakabe Erina , Aoki Reina , Taguchi Kana , Nishiyama Kanako , Yamashita Michiko , Sugimori Wakana , Kurata Mie , Fukushima Mana , Kitazawa Riko , Okada Kanako , Matsuda Megumi , Kamei Yoshiaki , Takada Yasutsugu 
Published: March 2020

Abstract
Background: The 2019 version 1 of the National Comprehensive Cancer Network guidelines states that magnetic resonance imaging (MRI)-based diagnosis of breast cancer “May be used for staging evaluation to define extent of cancer or presence of multifocal or multicentric cancer in the ipsilateral breast, or as screening of the contralateral breast cancer at time of initial diagnosis.” Therefore, we performed breast MRI to evaluate the extent of spread of breast cancer as part of the preoperative diagnosis.
Dual-energy computed tomography (DECT) is a new imaging technology that uses X-ray tube and detectors with two different tube voltages.
High-contrast and low-noise images, termed “virtual monochromatic image,” can be obtained using DECT. Recently, clinical cases using DECT have been reported in urology; however, only few cases have been reported on the diagnostic use of DECT for breast cancer.
Purpose: Evaluation of the usefulness of DECT in the preoperative diagnosis of extent of breast cancer spread.
Patients: Thirty-three patients with breast cancer, who underwent preoperative DECT and MRI, and were operated at our hospital from November 2016 to July 2018. The surgical specimens from the patients were excised horizontally. Patients who underwent preoperative chemotherapy were excluded from the study.
Methods: The maximum diameter, including that of the mass and non-mass enhancements in the horizontal sections of each lesion, was retrospectively measured by DECT and MRI. Moreover, the maximum diameter of the invading and intraductal lesions in the horizontal sections of the postoperative pathological sample were retrospectively measured.
In addition, the information on the patients’ background, clinical characteristics of the tumor, etc. were retrospectively collected and reviewed from the patients’ electronic medical records.
Results: The median age of the patients was 62 years. The median lesion size was 14.3 mm (0-75.8 mm) when measured with DECT, 13.1 mm (0-99.1 mm) with MRI, and 13 mm (3-95 mm) with postoperative pathology.
Spearman's rank correlation coefficient was 0.752 (p &lt;0.0001) for pathology and MRI measurements, 0.855 (p &lt;0.0001) for pathology and DECT measurements, and 0.892 (p &lt;0.0001) for MRI and DECT measurements. The correlations between both the pathology and DECT measurements, and MRI and DECT measurements were significantly positive.
Subgroup analysis of factors, such as age and menopausal status, showed significant positive correlation in all subgroups.
Conclusion: As compared to MRI, DECT is advantageous in that it can simultaneously perform a whole-body metastasis search and scan in the supine position, more closer to the surgical position. Furthermore, in this study, DECT was able to evaluate the extent of spread of lesions, including the intraductal extension, almost similar to that of MRI, suggesting that the diagnostic performance may not differ across subgroups.
Additional analysis, such as evaluation of the size of infiltrated area alone, will be conducted and reported in future.
Citation Format: Haruna Yamasawa, Akari Murakami, Megumi Takaoka, Erina Kusakabe, Reina Aoki, Kana Taguchi, Kanako Nishiyama, Michiko Yamashita, Wakana Sugimori, Mie Kurata, Mana Fukushima, Riko Kitazawa, Kanako Okada, Megumi Matsuda, Yoshiaki Kamei, Yasutsugu Takada. Evaluating the usefulness of dual-energy computed tomography for the preoperative diagnosis of the extent of spread of breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-02-12.