Assessment of extent of disease: digital breast tomosynthesis (DBT) versus full-field digital mammography (FFDM) Poster No.: C-1237 Congress: ECR 2012 Type: Scientific Paper Authors: N. Seo 1, H. H. Kim 1, H. J. Shin 1, J. H. Cha 1, H. Kim 1, J. H. Moon 2 ; 1 2 Seoul/KR, Anyang/KR Keywords: DOI: Breast, Mammography, Comparative studies 10.1594/ecr2012/C-1237 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 14
Purpose 1. Mammography is standard imaging modality for the early detection of breast cancer. However, it is well-known that false-negative rate of mammography is different substantially according to breast parenchymal density. Breast cancer might be masked by overlying breast tissue in women with dense breasts. 2. Digital breast tomosynthesis (DBT) is one of new techniques to overcome these limitations of mammography. A breast tomosynthesis system acquires multiple projection images by a digital detector from the X-ray tube moving along an arc. 3. The purpose of this study is to compare the diagnostic performances of digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) in lesion characterization and size measurement using breast specimens. Methods and Materials Study population From April 2008 to July 2009, 156 women with at least one breast lesion discovered by mammography and/or ultrasound (US) and who were scheduled for surgery, were prospectively enrolled in the study. Tomosynthesis in one view (mediolateral oblique, MLO) and standard digital mammography in two views (craniocaudal, CC and MLO) were acquired in the surgical specimens. We excluded 42 patients with more than one breast lesion seen in the breast specimens. Imaging acquisition protocol 1. Full-field digital mammography (FFDM) Standard two views (CC and MLO) Senographe DS, GE healthcare 2. Digital Breast tomosynthesis (DBT) One view (MLO) Senographe DS, GE healthcare Page 2 of 14
Image acquisition time (15 images): 20 sec Reconstruction time: 3 min Slice thickness: 1 mm Slab thickness: 11 mm Tube moving: step and shoot Rotation angle: 40 Image interpretation protocol 1. Three breast radiologists with clinical experience in breast imaging of between 3 and 15 years, performed in image interpretation. They evaluated the mammography and tomosynthesis images during different reading sessions with a time interval greater than four weeks, blinded to hisologic diagnosis. Image interpretation process is summarized in Fig.1. 2. Size measurement FFDM: largest dimension of lesion of any mammographic view DBT - At the slice of longest axis of a breast lesion - Microcalcifications: greater distance of microcalcifications 3. Probability of malignancy The probability of malignancy of each findings was categorized using the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) score: Benign group:birads 1, BIRADS 2, BIRADS 3 Malignant group: BIRADS 4A, BIRADS 4B, BIRADS 4C, BIRADS 5 4. Breast parenchymal density Breast density was rated as one of the four BI-RADS classes on the basis of the FFDM images and by one radiologist, as follows: Page 3 of 14
Fatty group: (1) fatty or <25% dense; (2) scattered fibroglandular densities or 25-50% dense Dense group: (3) heterogeneously dense or 50-75% dense;(4) dense or >75% dense. Data analysis The golden standard of an accurate diagnosis for all lesions was histology confirmed by surgery or excisional biopsy. We used a SPSS (version 15.0.0: SPSS; Chicago, IL, USA) for the data analysis. 1. Size measurment Paired t-test: difference between imaging and pathology Wilcoxon signed rank test: comparison between FFDM and DBT 2. Probability of malignancy Kappa value: pathologic accuracy for each reader McNemar test: comparison of pathologic accuracy between FFDM and DBT Images for this section: Page 4 of 14
Fig. 1: Every reader first localized the abnormal findings, classified the lesion type and measured the size of each possible lesion independently for each modality (DBT and FFDM). Following size measurement, the probability of malignancy of each findings was categorized using the BI-RADS score. After both reading sessions, readers selected the preferred modality between FFDM and DBT. Page 5 of 14
Results Pathology 1. Of the 114 patients with a single breast lesion, 30 had benign lesions and 84 had cancerous lesions. 2. Among the malignant breast tumors, 75 were invasive ductal carcinomas (IDC), three invasive lobular carcinomas (ILC), five mucinous carcinomas, one ductal carcinoma in situ (DCIS). 3. Various benign lesions were included such as intraductal papillomas (n=7), fibrocystic change (n=6), fibroadenomas (n=6), duct ectasia (n=3), nonproliferative breast change (n=3), sclerosing adenosis (n=2), ectopic breast tissue (n=2), and mammary hamartoma (n=1). Radiographic detection, lesion type, and parenchymal density 1. All breast lesions were detected by three readers on both DBT and FFDM. 2. Lesion types determined on FFDM were mass (n=48), mass with calcification (n=33), calcification (n=20), asymmetry with calcification (n=5), asymmetry (n=4), and distortion (n=4). 3. Breast parenchymal densities determined on FFDM were fatty breasts (n=35, 31%) and dense breasts (n=79, 69%). Size agreement between the respective imaging modality and pathology 1. The mean size of the surgical specimens was 81 mm. The median and mean pathologic lesion sizes were 22 mm and 27 mm (S.D. 21.6, range 2-160 mm). The mean size determined on DBT was 29 mm (range 3-107 mm), and the mean size determined by FFDM was 32 mm (range 4-115 mm). 2. As shown in Table 1, the mean differences of tumor size compared to the histopathology data were 1.6 mm and 4.4 mm, respectively, on DBT and FFDM. Size measurement by DBT was in stronger agreement with that of pathology than that measred by FFDM (P<0.001). Regardless of the parenchymal density, size evaluation obtained by DBT was more strongly correlated with that of pathology.(fig. 1,2,3) BIRADS classifications for the probability of malignancy Page 6 of 14
Table 2 demonstrates the agreement of the BIRADS assessment determined by DBT and FFDM, respectively, and with that of pathology. Overall, there was no statistically significant difference between DBT and FFDM for the characterization of breast lesions (p>0.05), though DBT was superior in dense breasts (p=0.03) (Fig. 1,2,3). The pathologic accuracy for each reader was calculated as a Kappa value, as shown in Table 3. Reader preferences of imaging modality Imaging modality preferences, i.e. DBT or FFDM or the same, are shown in Table 4. Readers 1 and 3 preferred DBT to FFDM, and reader 2 showed a similar preferences for each modality. Images for this section: Table 1: Size agreement by imaging modality and pathologic size according to breast parenchymal density. DBT = digital breast tomosynthesis, FFDM = full-field digital mammography *Paired t-test or Wilcoxon signed rank test **Wilcoxon signed rank test (comparison of accuracy in size measurement between DBT and FFDM) Page 7 of 14
Table 2: Pathologic accuracy of malignancy by imaging modality. *McNemar test (comparison of pathologic accuracy between DBT and FFDM) Table 3: Pathologic accuracy by each reader. Page 8 of 14
Table 4: Reader's preferences for imaging modality. Fig. 2: A 63-year-old female with invasive ductal carcinoma (parenchymal pattern 2) who underwent breast-conserving surgery. The pathologically determined size of her cancer was 27 mm. (a) FFDM. The mean size of the lesion as determined on FFDM, was 29.6 mm. (b) DBT. The mean size of the lesion on DBT was 26.3 mm. The mass is more clearly demarcated on DBT. All readers had a high suspicion of malignancy on both imaging modalities. Page 9 of 14
Fig. 3: A 63-year-old female with invasive ductal carcinoma (parenchymal pattern 2) who underwent breast-conserving surgery. The pathologically determined size of her cancer was 24 mm. (a) FFDM. The mean size of the lesion as determined on FFDM, was 31.0 mm. (b) DBT. The mean size of the lesion on DBT was 30.1 mm. Some part of the tumor margin is obscured on FFDM. All readers preferred DBT to FFDM and one reader had a higher suspicion of malignancy on DBT than FFDM. Fig. 4: A 45-year-old female with invasive ductal carcinoma (parenchymal pattern 3) who underwent breast-conserving surgery. The pathologic size of her cancer was 25 mm. (a) FFDM. The mean size of the lesion on FFDM was 18 mm. (b) DBT. The mean size of Page 10 of 14
the lesion on DBT was 24 mm. Although the mass is poorly delineated on FFDM due to overlying dense parenchyma, DBT demonstrates better margin visibility. Page 11 of 14
Conclusion In conclusion, DBT is superior to FFDM in the preoperative size measurement of breast lesions irregardless of the parenchymal density. Especially in dense breasts, DBT should then be more useful for rating for malignancy of the lesions. References 1. Heine, J.J. and P. Malhotra, Mammographic tissue, breast cancer risk, serial image analysis, and digital mammography. Part 1. Tissue and related risk factors. Acad Radiol, 2002. 9(3): p. 298-316. 2. Dobbins, J.T., 3rd and D.J. Godfrey, Digital x-ray tomosynthesis: current state of the art and clinical potential. Phys Med Biol, 2003. 48(19): p. R65-106. 3. Rafferty, E.A., Digital mammography: novel applications. Radiol Clin North Am, 2007. 45(5): p. 831-43, vii. 4. Mahesh, M., AAPM/RSNA physics tutorial for residents: digital mammography: an overview. Radiographics, 2004. 24(6): p. 1747-60. 5. Diekmann, F. and U. Bick, Breast tomosynthesis. Semin Ultrasound CT MR, 2011. 32(4): p. 281-7. 6. El-Bastawissi, A.Y., et al., Variation in mammographic breast density by race. Ann Epidemiol, 2001. 11(4): p. 257-63. 7. Carter, C.L., C. Allen, and D.E. Henson, Relation of tumor size, lymph node status, and survival in 24,740 breast cancer cases. Cancer, 1989. 63(1): p. 181-7. 8. Kinne, D.W., Staging and follow-up of breast cancer patients. Cancer, 1991. 67(4 Suppl): p. 1196-8. 9. Bonadonna, G., et al., Primary chemotherapy to avoid mastectomy in tumors with diameters of three centimeters or more. J Natl Cancer Inst, 1990. 82(19): p. 1539-45. Page 12 of 14
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21. Hieken, T.J., et al., Correlating sonography, mammography, and pathology in the assessment of breast cancer size. Am J Surg, 2001. 182(4): p. 351-4. 22. Pierie, J.P.E.N., et al., Clinical assessment, mammography and ultrasonography as methods of measuring the size of breast cancer: a comparison. Breast, 1998. 7(5): p. 247-250. 23. Pritt, B., et al., Influence of breast cancer histology on the relationship between ultrasound and pathology tumor size measurements. Mod Pathol, 2004. 17(8): p. 905-10. 24. Flanagan, F.L., et al., Invasive breast cancer: mammographic measurement. Radiology, 1996. 199(3): p. 819-23. 25. Pain, J.A., et al., Assessment of breast cancer size: a comparison of methods. Eur J Surg Oncol, 1992. 18(1): p. 44-8. 26. Helvie, M.A., Digital mammography imaging: breast tomosynthesis and advanced applications. Radiol Clin North Am, 2010. 48(5): p. 917-29. Personal Information Nieun Seo, MD., Hak-Hee Kim, MD. Department of Radiology, Research Institute of radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea E-mail:hhkim@amc.seou.kr Page 14 of 14