• Investigative Magnetic Resonance Imaging
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• 제16권1호
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• pp.16-24
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• 2012

목적: Dixon 정량 화학적 변위 자기공명영상(QCSI)의 척추 골수 지방함량과 이중에너지 방사선 흡수법 (DXA)를 통한 BMD 값과의 상관성을 알아본다. 대상과 방법: QCSI와 간의 화학적 변위영상을 포함한 전신 자기공명영상(MRI)과 요추의 DXA를 시행한 68명의 건강한 사람들[평균연령, 50.7세; 범위, 25-76세; 남/여=36/32]을 대상으로 후향적 연구를 시행하였다. 성별과 T-score에 따라 정상(남/여=27/23)과 골감소증(남/여=9/9)집단으로 나누고, MRI로 척추골수와 간의 지방함량을 측정하였다. 각 집단의 나이, 체질량지수(BMI), 골수 지방함량과 간의 지방함량을 비교하였고, 여성에서는 폐경 전후 각 변수들의 비교를 추가하여 Spearman's 상관계수로 평가하였다. 결과: 남성의 나이, BMI, 척추 골수와 간의 지방함량은 정상과 골감소증 집단 사이에 큰 차이를 보이지 않았다. 여성에서는, 골감소증 집단의 평균 나이가 정상집단에 비해 높았고(p=0.01), 폐경된 경우가 많았으나[폐경 전, 26.1%(6/23); 후, 77.8%(7/9); p<0.05], 다른 변수들은 유의한 차이를 보이지 않았다. 골수 지방함량과의 비교에 있어 여성의 나이는 유일한 의미 있는 변수였다(r=0.43, p<0.05). 결론: Dixon QCSI를 통한 척추 골수 지방함량의 측정은 남녀 모두에 있어 DXA BMD 감소를 정확히 반영하지는 않는다.

• Investigative Magnetic Resonance Imaging
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• 제21권1호
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• pp.28-33
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• 2017

Purpose: To investigate and compensate the effects of respiration-induced B0 variations on fat quantification of the bone marrow in the lumbar spine. Materials and Methods: Multi-echo gradient echo images with navigator echoes were obtained from eight healthy volunteers at 3T clinical scanner. Using navigator echo data, respiration-induced B0 variations were measured and compensated. Fat fraction maps were estimated using $T2^*$-IDEAL algorithm from the uncompensated and compensated images. For manually drawn bone marrow regions, the estimated B0 variations and the calculated fat fractions (before and after compensations) were analyzed. Results: An increase of temporal B0 variations from inferior level to superior levels was observed for all subjects. After compensation using navigator echo data, the effects of the B0 variations were reduced in gradient echo images. The calculated fat fractions show significant differences (P < 0.05) in L1 and L3 between the uncompensated and the compensated. Conclusion: The results of this study raise the need for considering respiration-induced B0 variations for accurate fat quantification using gradient echo images in the lumbar spine. The use of navigator echo data can be an effective way for the reduction of the effects of respiratory motion on the quantification.

• Korean Journal of Radiology
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• 제22권10호
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• pp.1671-1679
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• 2021

Objective: We quantitatively measured the fat fraction (FF) in the vertebrae of patients with ankylosing spondylitis (AS) using magnetic resonance imaging (MRI) and investigated the role of FF as an indicator of both active inflammation and chronicity. Materials and Methods: A total of 52 patients with AS who underwent spinal MRI were retrospectively evaluated. The FF values of the anterosuperior and anteroinferior corners of the bone marrow in the L1-S1 spine were assessed using the modified Dixon technique. AS activity was measured using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), AS Disease Activity Score (ASDAS), and serum inflammatory marker levels. AS disease chronicity was assessed by AS disease duration and the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Univariable and multivariable regression analyses were conducted to investigate the correlation between FF and other clinical characteristics. Results: The mean FF ± standard deviation of the total lumbar spine was 43.0% ± 11.3%. At univariable analysis, spinal FF showed significant negative correlation with BASDAI (β = -0.474, p = 0.002) and ASDAS with C-reactive protein (ASDAS-CRP; β = -0.478, p = 0.002) and a significant positive correlation with AS disease duration (β = 0.440, p = 0.001). After adjusting for patient age, sex, and total mSASSS score, spinal FF remained significantly negatively correlated with BASDAI (β = -0.543, p < 0.001), ASDAS-CRP (β = -0.568, p < 0.001), and ASDAS with erythrocyte sedimentation rate (β = -0.533, p = 0.001). Spinal FF was significantly lower in patients with very high disease activity (ASDAS-CRP > 3.5) than in those with only high disease activity (2.1 ≤ ASDAS-CRP ≤ 3.5) (p = 0.010). Conclusion: Spinal FF may help assess both AS disease activity and chronicity.