Enhanced imaging with multi-pinhole single-photon emission computed tomography

单光子发射计算机断层扫描(SPECT)是一种常用的成像方式。现在使用的心脏专用多针孔摄像头带有固态探测器，具有更高的灵敏度和更高的空间、能量和时间分辨率，可以进行动态3D成像。然而，针孔准直器在相机的视场中产生不同的分辨率、放大率和灵敏度。这些因素会导致图像伪影，可能导致不准确的解释和误诊。它们还增加了校正图像退化因素的难度，例如衰减、散射、患者运动，这些因素对于准确的定性和定量评估是必不可少的。多针孔SPECT目前的解释没有任何这些校正，降低了图像质量和测试精度。我的计划的长期目标是提高多针孔心脏SPECT(/CT)成像的定量准确性和精密度。我的短期目标是：目标1)开发新的方法，利用数据一致性条件对传输和排放数据集进行联合配准，以达到衰减校正的目的。目的2)利用精确的散射模型对来自低能量窗的信号进行积分，从而提高针孔SPECT图像的信噪比。目的3)发展新的运动校正方法(MC)用于动态SPECT成像，以提高MBF测量的准确性、精密度和重复性。我的实验室的一般方法是使用解析或蒙特卡罗计算机模拟来开发和验证先进的图像重建和分析方法，然后使用物理模型实验和来自真实患者研究的数据集进行评估。衰减、散射和运动强烈依赖于身体的形状和大小。因此，在选择用于评估的数据集时，我们使用混合扫描来确保对性别、体型和尺寸进行多样化采样。心外信号违反了数据一致性条件的假设，因此目标1将使用心脏收缩运动将心脏从静态背景信号中分离出来。目标2和目标3将使用机器学习(ML)来估计能量范围内的散射，并从动态成像中配准图像和估计运动。建议的工作将利用获取的SPECT数据的能量维和时间维来增强和扩展可用于医学成像的信息。我的实验室为本科生和研究生教育提供了丰富的培养环境。作为CAMPEP认可的渥太华-卡尔顿医学物理联合项目的一部分，学生与从事各种医学物理项目的其他人互动。作为渥太华大学心脏研究所的一部分，学生们还可以接触到推动这一领域大部分研究的医学动机，以及该领域广泛的多学科性质，接触从微生物学到放射化学和组织工程的研究。

Single-photon emission computed tomography (SPECT) is a commonly used imaging modality. Cardiac-specific multi-pinhole cameras with solid-state detectors are now in use that have improved sensitivity and improved spatial, energy and temporal resolution allowing dynamic 3D imaging. However, pinhole collimators produce variable resolution, magnification, and sensitivity across the camera's field of view. These factors lead to image artifacts that may cause inaccurate interpretation and misdiagnosis. They also make it more difficult to correct for image degrading factors such as attenuation, scatter, patient motion, which is essential for accurate qualitative and quantitative evaluation. Multi-pinhole SPECT is currently interpreted without any of these corrections, reducing image quality and test accuracy. The long-term goal of my program is to improve the quantitative accuracy and precision of imaging with multi-pinhole cardiac SPECT(/CT). My short-term objectives are: Aim 1) Develop novel methods for co-registration of transmission and emission datasets using data consistency conditions for the purpose of attenuation correction. Aim 2) Use accurate scatter modeling to integrate the signal from lower energy windows and thereby increase the signal-to-noise ratio (SNR) of pinhole SPECT images. Aim 3) Develop novel methods of motion correction (MC) for dynamic SPECT imaging to improve the accuracy, precision and repeatability of MBF measurements. The general approach of my laboratory is to develop and validate advanced image reconstruction and analysis methods using analytic or Monte Carlo computer simulations, followed by evaluation using physical phantom experiments and datasets from real patient studies. Attenuation, scatter and motion depend strongly on body shape and size. Thus in selecting data sets for evaluation, we use a mixture of scans to ensure a diverse sampling of sexes, body shapes and sizes. Extra-cardiac signals violate the assumptions of the data consistency conditions, so Aim 1 will use cardiac contractile motion to separate the heart from static background signals. Aims 2 and 3 will use machine-learning (ML) to estimate scatter over a range of energies and to register images and estimate motion from dynamic imaging. The proposed work will exploit the energy-dimension and time-dimension of the acquired SPECT data to enhance and expand the information available for medical imaging. My lab provides a rich training environment for undergraduate and graduate student education. As part of the CAMPEP accredited Ottawa-Carleton joint program in medical physics, students interact with others engaged in a wide variety of medical physics projects. As part of the University of Ottawa Heart Institute, students are also exposed to the medical motivation that drives much of this field of research as well as to the broad multi-disciplinary nature of this field with exposure to research from microbiology to radiochemistry and tissue engineering.