Burk Laurel M, Wang Ko-Han, Wait John Matthew, Kang Eunice, Willis Monte, Lu Jianping, Zhou Otto, Lee Yueh Z
Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America.
Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America.
PLoS One. 2015 Jan 30;10(1):e0115607. doi: 10.1371/journal.pone.0115607. eCollection 2015.
We aim to demonstrate the application of free-breathing prospectively gated carbon nanotube (CNT) micro-CT by evaluating a myocardial infarction model with a delayed contrast enhancement technique. Evaluation of murine cardiac models using micro-CT imaging has historically been limited by extreme imaging requirements. Newly-developed CNT-based x-ray sources offer precise temporal resolution, allowing elimination of physiological motion through prospective gating. Using free-breathing, cardiac-gated CNT micro-CT, a myocardial infarction model can be studied non-invasively and with high resolution. Myocardial infarction was induced in eight male C57BL/6 mice aged 8-12 weeks. The ischemia reperfusion model was achieved by surgically occluding the LAD artery for 30 minutes followed by 24 hours of reperfusion. Tail vein catheters were placed for contrast administration. Iohexol 300 mgI/mL was administered followed by images obtained in diastole. Iodinated lipid blood pool contrast agent was then administered, followed with images at systole and diastole. Respiratory and cardiac signals were monitored externally and used to gate the scans of free-breathing subjects. Seven control animals were scanned using the same imaging protocol. After imaging, the heart was harvested, cut into 1mm slices and stained with TTC. Post-processing analysis was performed using ITK-Snap and MATLAB. All animals demonstrated obvious delayed contrast enhancement in the left ventricular wall following the Iohexol injection. The blood pool contrast agent revealed significant changes in cardiac function quantified by 3-D volume ejection fractions. All subjects demonstrated areas of myocardial infarct in the LAD distribution on both TTC staining and micro-CT imaging. The CNT micro-CT system aids straightforward, free-breathing, prospectively-gated 3-D murine cardiac imaging. Delayed contrast enhancement allows identification of infarcted myocardium after a myocardial ischemic event. We demonstrate the ability to consistently identify areas of myocardial infarct in mice and provide functional cardiac information using a delayed contrast enhancement technique.
我们旨在通过使用延迟对比增强技术评估心肌梗死模型，来演示自由呼吸前瞻性门控碳纳米管（CNT）微型计算机断层扫描（micro-CT）的应用。历史上，使用微型计算机断层扫描成像评估小鼠心脏模型一直受到极端成像要求的限制。新开发的基于碳纳米管的X射线源提供了精确的时间分辨率，允许通过前瞻性门控消除生理运动。使用自由呼吸、心脏门控的碳纳米管微型计算机断层扫描，可以对心肌梗死模型进行非侵入性的高分辨率研究。对8只8-12周龄的雄性C57BL/6小鼠诱导心肌梗死。通过手术阻断左前降支动脉30分钟，然后再灌注24小时，建立缺血再灌注模型。放置尾静脉导管用于注射造影剂。注射300 mgI/mL的碘海醇，然后在舒张期采集图像。随后注射碘化脂质血池造影剂，接着在收缩期和舒张期采集图像。外部监测呼吸和心脏信号，并用于门控自由呼吸受试者的扫描。使用相同的成像方案对7只对照动物进行扫描。成像后，取出心脏，切成1毫米厚的切片，并用TTC染色。使用ITK-Snap和MATLAB进行后处理分析。所有动物在注射碘海醇后，左心室壁均出现明显的延迟对比增强。血池造影剂显示，通过三维容积射血分数量化的心脏功能有显著变化。在TTC染色和微型计算机断层扫描成像上，所有受试者在左前降支分布区域均显示出心肌梗死区域。碳纳米管微型计算机断层扫描系统有助于进行直接的、自由呼吸的、前瞻性门控的三维小鼠心脏成像。延迟对比增强可以在心肌缺血事件后识别梗死心肌。我们展示了一致识别小鼠心肌梗死区域的能力，并使用延迟对比增强技术提供心脏功能信息。
