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Table 1. Differential MRI Findings of Tuberculous Spondylitis and Pyogenic Spondylitis (p <0.05) MR Findings % (No. of Cases) Tuberculous Pyogenic Margin of paraspinal mass/abscess Smooth 067 (28/42) 06 (1/18) Irregular 031 (13/42) 44 (8/18) Infiltrating 002 (1/42) 50 (9/18) Grade of endplate erosion None 000 (0/42) 06 (1/18) Mild 052 (22/42) 38 (7/18) Severe 048 (20/42) 56 (10/18) Paraspinal mass/abscess Absence 000 (0/42) 94 (17/18) Presence 100 (42/42) 06 (1/18) Central dark signal intensity on T2WI Absence 014 (6/42) 61 (11/18) Presence 086 (36/42) 39 (7/18) Subligamentous spread Absence 019 (8/42) 50 (9/18) Presence 081 (34/42) 50 (9/18) Grade of vertebral collapse None 040 (17/42) 78 (14/18) Mild 040 (17/42) 11 (2/18) Severe 020 (8/42) 11 (2/18) Posterior element extension Absence 038 (16/42) 67 (12/18) Presence 062 (26/42) 33 (6/18) The discriminant MR findings in step-wise discriminant analysis. 184
A B C D E F G H Fig. 1. Tuberculous spondylitis in 39-yearold woman. A-C. Sagittal T1-, T2-, and contrast-enhanced T1-weighted images show subligamentous spread (arrows), and paraspinal and intraosseous abscesses with smooth rim enhancement. D-F. Axial T1-, T2-, and contrast-enhanced T1-weighted images show bilateral paraspinal abscesses (arrows) with rim enhancement at the level of T8. G, H. Axial T2- and contrast-enhanced T1- weighted images show right paraspinal abscess with central dark signal focus and rim enhancement at the level of T7 (arrows). 185
김소영 외: 결핵성 척추염과 화농성 척추염의 감별진단 Fig. 2. Pyogenic spondylitis in 7-yearold girl. A, B. Sagittal T1- and T2- weighted images show severe endplate erosion (arrowhead) and disc space narrowing in L3 and L4 spines. C, D. Axial T1- and T2-weighted images show ill-defined paraspinal infiltration of inflammation in right psoas muscle (arrow) at the level of L4. A B C D 재 여부, 추간판 간격 감소의 정도, 테두리 조영 증강된 농양 의 개수와 크기 등은 두 군 간에 통계학적으로 유의한 차이를 보이지 않았으며, 또한 두 질환의 감별에 판별력 있는 소견도 아니었다. MR 평가자에 의한 진단의 정확도는 결핵성 척추염 89%, 화농성 척추염 65%이었다. 단계적 판별 분석 프로그램에서 판 별력 있었던 3가지 MR 소견으로 두 질환을 감별하였을 때 진 단의 정확도는 결핵성 척추염 90.5%, 화농성 척추염 83.3% 이었다. 고 찰 감염성 척추염은 환자들의 증상과 임상증상이 흔히 비 특이 적이며 다양하게 나타나며 척추염의 확진과 감염 부위의 위치 파악에는 영상학적 판단이 중요하다(4, 7, 11). 감염성 척추염 은 경막 외측에 존재하는 척추 구성 성분의 감염으로 척추체 가 가장 흔하게 침범되는 부위지만 척추의 후방 구조물이나 추간판, 경막 외 공간이나 척추 주위의 연부조직까지 일차적 이나 이차적으로 침범될 수 있다(2, 12). 감염성 척추염의 호 발 위치는 흉추나 요추 부위가 가장 흔한 것으로 알려졌으며 (13-15) 본 연구에서도 침범된 척추체가 대부분 흉추와 요 추 부위였다. 결핵성 척추염은 혈행성, 주위 림프절로부터 파급, 지주막하 강으로부터의 파급에 의한 이차적이거나, 원발 부위가 없이 직 접적인 결핵균에 의한 일차적 침범에 의해서도 발생할 수 있 다. 병리학적으로 척추의 전측부에서 서서히 진행하여 척추체 주위에 농양을 형성하지만 결핵균은 단백 분해 효소를 생산하 지 않아서 비교적 진행된 경우에만 추간판을 침범한다(4, 1619). 또한, 병기가 진행되어 급속한 골파괴에 의한 구조적인 척추기형이나 결핵균의 직접적인 척추관(spinal canal) 침입 시에는 신경학적 후유증이 증가함으로써 불량한 예후를 가져 오기 때문에 조기에 항결핵제 치료나 수술적 배농술 또는 척 추융합술 등 적절한 치료를 하여야 한다(1, 16). 반면에 화농성 척추염은 비교적 드물게 발생하며 병원균이 186
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Tuberculous Spondylitis vs Pyogenic Spondylitis: Focusing on the Discriminative MR Findings for Differentiation 1 So Young Kim, M.D., Suk Joo Hong, M.D., Chang Yoon Lee, M.D., Kyoo Byung Chung, M.D., Cheol Min Park, M.D. 1 Department of Diagnostic Radiology, College of Medicine, Korea University Purpose: The purpose of this study is to analyze the most discriminative MR findings for making the differential diagnosis of tuberculous and pyogenic spondylitis. Materials and Methods: Sixty MR scans of 18 pyogenic spondylitis patients and 42 tuberculous spondylitis patients were retrospectively reviewed. The statistical analysis was performed using stepwise discriminant analysis and Student s T-test. Results: The patients with tuberculous spondylitis had a significantly higher incidence of MRI findings as follows (p <0.05): smooth margin of a paraspinal mass/abscess in 67% [28/42] of the tuberculous spondylitis patients vs 6% [1/18] in the pyogenic spondylitis patients, mild endplate erosion in 52% [22/42] vs 38% [7/18], respectively, the presence of paraspinal mass/abscess in 100% [42/42] vs 6% [1/18], respectively, central dark signal intensity of the abscess in 86% [36/42] vs 39% [7/18]), respectively, subligamentous spread in 81% [34/42] vs 50% [9/18]), respectively, severe vertebral collapse in 20% [8/42] vs 11% [2/18]), respectively, and posterior extension in 62% [26/42] vs 33% [6/18]), respectively. Among of them, the significant discriminative MR findings were the margin of a paraspinal mass, the grade of endplate erosion and the presence or absence of a paraspinal mass in that order. Conclusion: In the differentiation of tuberculous and pyogenic spondylitis, the margin of the paraspinal mass, the grade of endplate erosion and the presence or absence of a paraspinal mass are the most three discriminating MR findings in that order. Index words : Spine, infection Magnetic resonance (MR), comparative studies Spondylitis Address reprint requests to : Suk Joo Hong, M.D., Department of Diagnostic Radiology, College of Medicine, Korea University 80 Guro-dong, Guro-gu, Seoul 152-703, Korea Tel. 82-2-818-6183 Fax. 82-2-818-9282 E-mail: hongsj@korea.ac.kr 189