Benign and Malignant Thyroid Nodules: US Differentiation--Multicenter Retrospective Study

doi:10.1148/radiol.2473070944

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Head and Neck Imaging

Benign and Malignant Thyroid Nodules: US Differentiation—Multicenter Retrospective Study¹

Won-Jin Moon, MD, So Lyung Jung, MD, Jeong Hyun Lee, MD, Dong Gyu Na, MD, Jung-Hwan Baek, MD, Young Hen Lee, MD, Jinna Kim, MD, Hyun Sook Kim, MD, Jun Soo Byun, MD, Dong Hoon Lee, MD, For the Thyroid Study Group, Korean Society of Neuro- and Head and Neck Radiology

¹ From the Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea (W.J.M.); Department of Radiology, Konkuk University Hospital, Konkuk University School of Medicine, 4-12, Hwayang-dong, Gwangjin-gu, Seoul 143-914, Korea (W.J.M.); Department of Radiology, Kangnam St Mary's Hospital, Catholic University College of Medicine, Seoul, Korea (S.L.J.); Department of Radiology, Asan Medical Center, Ulsan University College of Medicine, Seoul, Korea (J.H.L.); Department of Radiology, Seoul National University Hospital, Seoul National University, Seoul, Korea (D.G.N., D.H.L.); Department of Radiology, Thyroid Center, Daerim St Mary's Hospital, Seoul, Korea (J.H.B.); Department of Radiology, Anam Hospital, Korea University School of Medicine, Seoul, Korea (Y.H.L.); Department of Radiology, Severance Hospital, Yonsei University School of Medicine, Seoul, Korea (J.K.); Department of Radiology, Nowon Eulji Hospital, Eulji University School of Medicine, Seoul, Korea (H.S.K.); and Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea (J.S.B.). Received June 5, 2007; revision requested August 8; revision received September 27; accepted November 21; final version accepted December 4. Address correspondence to W.J.M. (e-mail: mdmoonwj{at}naver.com).

Purpose: To retrospectively evaluate the diagnostic accuracy of ultrasonographic(US) criteria for the depiction of benign and malignant thyroid nodulesby using tissue diagnosis as the reference standard.

Materials and Methods: This study had institutional review boardapproval, and informed consent was waived. From January 2003 throughJune 2003, 8024 consecutive patients had undergone thyroid US atnine affiliated hospitals. A total of 831 patients (716 women, 115men; mean age, 49.5 years ± 13.8 [standard deviation]) with849 nodules (360 malignant, 489 benign) that were diagnosed at surgeryor biopsy were included in this study. Three radiologists retrospectivelyevaluated the following characteristics on US images: nodule size,presence of spongiform appearance, shape, margin, echotexture, echogenicity,and presence of microcalcification, macrocalcification, or rim calcification.A ${chi}$ ² test and multiple regression analysis were performed. Sensitivity,specificity, and positive and negative predictive values were obtained.

Results: Statistically significant (P < .05) findings of malignancywere a taller-than-wide shape (sensitivity, 40.0%; specificity, 91.4%),a spiculated margin (sensitivity, 48.3%; specificity, 91.8%), markedhypoechogenicity (sensitivity, 41.4%; specificity, 92.2%), microcalcification(sensitivity, 44.2%; specificity, 90.8%), and macrocalcification(sensitivity, 9.7%; specificity, 96.1%). The US findings for benignnodules were isoechogenicity (sensitivity, 56.6%; specificity, 88.1%;P < .001) and a spongiform appearance (sensitivity, 10.4%; specificity,99.7%; P < .001). The presence of at least one malignant US findinghad a sensitivity of 83.3%, a specificity of 74.0%, and a diagnosticaccuracy of 78.0%. For thyroid nodules with a diameter of 1 cm orless, the sensitivity of microcalcifications was lower than thatin larger nodules (36.6% vs 51.4%, P < .05).

Conclusion: Shape, margin, echogenicity, and presence of calcificationare helpful criteria for the discrimination of malignant from benignnodules; the diagnostic accuracy of US criteria is dependent on tumorsize.

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