An Ultra High Resolution SPECT System Integrated with a High-Field MRI Scanner

描述（由申请人提供）：在本项目中，我们将开发一种新型成像系统，该系统结合了高场MRI扫描仪和高分辨率SPECT系统，用于对胰腺β细胞中的代谢和信号传导靶点进行成像。该组合系统包括9.4 T 30 cm水平孔磁体（Oxford Instrument，Oxford，UK）和配备有12 cm屏蔽梯度（最大强度为400 mT/m）的Bruker Avance Biospec（Bruker-Biospin，Billerica，MA）控制台，以及紧凑型和高分辨率SPECT系统，该系统将安装在12 cm直径孔内，以允许同时对小鼠进行MR和SPECT成像。所提出的SPECT系统是基于能量分辨光子计数探测器。它由像素化CdZnTe（CZT）晶体（350 5 m W 350 5 m间距）组成，耦合到定制设计的读出电路，该读出电路利用能量分辨光子计数（ERPC）ASIC（由孟博士在UI的小组开发）读出阳极像素和NCI-ASIC（由布鲁克海文国家实验室和海军研究实验室开发）读出阴极信号。ERPC探测器提供（a）高的固有空间分辨率（在所有三个维度上<400 μ m），（B）覆盖12- 200 keV的宽动态范围，（c）具有最小化的磁性部件的经证明的MRI兼容性，（d）提取在相邻阳极像素和阴极上同时感应的信号的能力，其提供了用于校正由强磁场引起的事件定位误差的关键信息，以及（e）用于将多个探测器封装到MRI孔中的紧凑形状因子。所提出的成像系统结合了高场（9.4 T）MRI扫描仪与SPECT系统。它允许在MR和SPECT图像中分辨的特征的出色的配准。所提出的系统将被应用于成像胰腺β细胞中的代谢和信号传导目标。研究结果将增强我们对每种成像方式在2cell丢失和复制的特定模型中的优势和局限性的理解。 公共卫生相关性：2型糖尿病（T2 DM）是我们这个时代最重要的医学问题之一，其发病率急剧增加，在美国影响超过2000万人，并且占总医疗费用和工资损失超过2000亿美元/年。治疗自身免疫性1型糖尿病的新方法也将受益于b细胞质量/功能的评估，以监测免疫攻击和可能的持续复制以及移植胰岛或由干细胞或其他祖细胞产生的b细胞的命运[9-11]。有用的，经过验证的技术仍然是一个长期追求的目标。在这个项目中，我们将开发一个组合SPECT/MRI系统，专门用于成像放射性标记的细胞在小实验室动物。该系统将为非侵入性评估小鼠b细胞质量和功能提供独特的工具。我们还期望高分辨率SPECT系统和高场MRI系统的组合将对许多其他领域产生重大影响，例如放射性标记干细胞和T细胞的体内跟踪，以及小动物中的肿瘤成像。

DESCRIPTION (provided by applicant): In this project, we will develop a novel imaging system that combines a high-field MRI scanner and an ultrahigh resolution SPECT system for imaging metabolic and signaling targets in the pancreatic beta cell. This combined system comprises a 9.4 T 30 cm horizontal bore magnet (Oxford Instrument, Oxford, UK) with Bruker Avance Biospec (Bruker-Biospin, Billerica, MA) console equipped with 12 cm shielded gradient with maximum strength of 400mT/m, and a compact and ultrahigh resolution SPECT system that will be fitted inside the 12 cm diameter bore to allow simultaneous MR and SPECT imaging of mouse. The proposed SPECT system is based on an energy-resolved photon counting detector. It consists of pixelated CdZnTe (CZT) crystals (with 350 5m W 350 5m pitch), coupled to a custom- designed readout circuitry that utilizes an energy-resolved photon-counting (ERPC) ASIC (developed by Dr. Meng's group at UI) to readout anode pixels and the NCI-ASIC (developed by Brookhaven National Laboratory and Naval Research Laboratory) to readout the cathode signals. The ERPC detector offers (a) an ultrahigh intrinsic spatial resolution (<400 5m in all three dimensions) for 140keV 3-rays, (b) a wide dynamic range to cover 12-200keV, (c) a proven MRI- compatibility with minimized magnetic components, (d) the ability to extract signals simultaneously induced on adjacent anode pixels and the cathode, which provides critical information for correcting the event positioning error induced by the strong magnetic field, and (e) a compact form factor for packing multiple detectors into the MRI bore. The proposed imaging system combines a high-field (9.4 T) MRI scanner with an ultrahigh SPECT system. It allows an excellent co-registration of the features resolved in both MR and SPECT images. The proposed system will be applied for imaging metabolic and signaling targets in the pancreatic beta cell. The results of studies will enhance our understanding of the advantages and limitations of each imaging modality in specific models of 2cell loss and replication. PUBLIC HEALTH RELEVANCE: Type 2 diabetes mellitus (T2DM) is one of the most important medical problems of our time, with a dramatically increasing incidence affecting over 20 million persons in the United States and accounting for over $200 billion/yr in total medical costs and lost wages. New methods to treat autoimmune Type 1 diabetes would also benefit from an assessment of b-cell mass/function to monitor immune attack and possible ongoing replication as well as the fate of transplanted islets or b-cells generated from stem or other progenitor cells [9-11]. Useful, validated techniques to remains a long sought after target. In this project, we will develop a combined SPECT/MRI system that is dedicated to imaging radiolabeled cells in small lab animals. This system would offer a unique instrument for non-invasively assess b-cell mass and function in mice. We expect also that the combination of the ultrahigh resolution SPECT system and high-field MRI system would make a substantial impact to many other areas, such as in vivo tracking of radiolabeled stem cells and T cells, as well as imaging tumors in small animals.