Alford Sara K, Sadowski Elizabeth A, Unal Orhan, Polzin Jason A, Consigny Daniel W, Korosec Frank R, Grist Thomas M
Department of Biomedical Engineering, University of Wisconsin-Madison, 53792-3252, USA.
J Magn Reson Imaging. 2005 Sep;22(3):347-53. doi: 10.1002/jmri.20389.
To determine the feasibility and sensitivity of blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) to detect acute renal ischemia, using a swine model, and to present the causes of variability and assess techniques that minimize variability introduced during data analysis.
BOLD MRI was performed in axial and coronal planes of the kidneys of five swine. Color R2* maps were calculated and mean R2* values and 95% confidence intervals (CIs) for the cortex and medulla were determined for baseline, renal artery occlusion and reperfusion conditions. Paired Student's t-tests were used to determine significance.
Mean R2* measurements increased from baseline during renal artery occlusion in the cortex (axial, 13.8-24.6 second(-1); coronal, 14.4-24.7 second(-1)) and medulla (axial, 19.3-32.2 second(-1); coronal, 20.1-30.7 second(-1)). These differences were significant for both the cortex (axial, P < 0.04; coronal, P < 0.005) and medulla (axial, P < 0.02; coronal, P < 0.0005). No significant change was observed in the contralateral kidney.
R2* values were significantly higher than baseline for medulla and cortex during renal artery occlusion. More variability exists in R2* measurements in the medulla than the cortex and in the axial than the coronal plane.
使用猪模型，确定血氧水平依赖（BOLD）磁共振成像（MRI）检测急性肾缺血的可行性和敏感性，并阐述变异性的原因，评估在数据分析过程中可将变异性降至最低的技术。
对5头猪的肾脏在轴位和冠状位进行BOLD MRI检查。计算彩色R2图，并确定皮质和髓质在基线、肾动脉闭塞和再灌注条件下的平均R2值及95%置信区间（CI）。采用配对t检验确定显著性。
在肾动脉闭塞期间，皮质（轴位，13.8 - 24.6秒⁻¹；冠状位，14.4 - 24.7秒⁻¹）和髓质（轴位，19.3 - 32.2秒⁻¹；冠状位，20.1 - 30.7秒⁻¹）的平均R2*测量值均高于基线。皮质（轴位，P < 0.04；冠状位，P < 0.005）和髓质（轴位，P < 0.02；冠状位，P < 0.0005）的这些差异均具有显著性。对侧肾脏未观察到显著变化。
肾动脉闭塞期间，髓质和皮质的R2值显著高于基线。髓质R2测量值的变异性比皮质更大，轴位的变异性比冠状位更大。
