Journal of Surgical Ultrasound is an Open Access Journal. All articles are distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright ⓒ 2020 by The Korean Surgical Ultrasound Society pISSN 2288-9140 eISSN 2671-7883 젊은 유방암 환자에서 수술 전 유방초음파와 자기공명영상의 종양 크기 측정 정확도 비교 전북대학교 의과대학 외과학교실 유방ㆍ갑상선외과, 1 전북대학교 의과대학 영상의학과 강상율, 최은정 1 , 변정희 1 , 안하림, 윤현조, 정성후 Comparative Accuracy of Preoperative Tumor Size Assessment on Breast Ultrasonography and Magnetic Resonance Imaging in Young Breast Cancer Patients Sang Yull Kang, Eun Jung Choi 1 , Jung Hee Byon 1 , Ha Rim Ahn, Hyun Jo Youn, Sung Hoo Jung Division of BreastㆍThyroid Surgery, Department of Surgery, Jeonbuk National University Medical School, 1 Departmenet of Radiology, Jeonbuk National University Medical School, Jeonju, Korea Received March 5, 2020 Revised March 31, 2020 Accepted April 6, 2020 Purpose: Breast cancer in young women deserves special consideration, such as dense breast, more aggressive progression, and oncoplastic surgery. Magnetic resonance imaging (MRI) is a more recent modality than ultrasonography (US), but the role of MRI in patients with a dense breast is still controversial. This comparative study analyzed the relationship between the preoperative radiological and the postoperative pathological tumor size for young breast cancer patients. Methods: All breast cancers diagnosed in patients 45 years or younger from January 2016 to December 2018 were reviewed. Tumor size measurements obtained on breast US and MRI were compared for accuracy with those obtained in the final pathology results. Patients with only microcalcification on imaging modalities and those who had undergone neoadjuvant chemotherapy were excluded. Results: A total of 103 breast cancer patients were included in this study. Of the 103 breast cancers with both imaging modalities performed, 86 (83.5%) were infiltrating ductal carci- nomas and 17 (16.5%) were ductal carcinoma in situ. The mean tumor size measured on MRI was significantly greater than that measured on pathology (18.5 ± 11.0 mm vs. 16.6 ± 8.5 mm), whereas the sizes measured on US was not significantly different from that meas- ured on pathology (16.5 ± 9.5 mm vs. 16.6 ± 8.5 mm). The tumor size measured on MRI was greater than that measured on US. Conclusion: Measurements taken by US were more accurate in measuring the tumor size in patients 45 years of age or younger than MRI. Keywords: Breast neoplasms, Ultrasonography, Tumor burden, Magnetic resonance imaging Correspondence to: Hyun Jo Youn Division of BreastㆍThyroid Surgery, Department of Surgery, Jeonbuk National University Medical School, 20 Geonji-ro, Deokjin-gu, Jeonju 54907, Korea Tel: +82-63-250-2389 Fax: +82-63-271-6197 E-mail: yhj0903@jbnu.ac.kr JSU Journal of Surgical Ultrasound ORIGINAL ARTICLE J Surg Ultrasound 2020;7:7-13 https://doi.org/10.46268/jsu.2020.7.1.7