IMPROVED QUANTITATIVE GA-65 SPECT IMAGING

描述（改编自申请人的摘要）： 研究的目的是改善获取，重建和提取 从Ga-67 SPECT数据的定量信息，并评估这些 使用任务相关标准改进成像系统。 镓 已被证明是一种有用的核医学示踪剂， 肿瘤，并且已知镓亲和力与 组织病理学肿瘤分级。 然而，对Ga-67进行成像具有挑战性，因为 它会发射出许多高能光子 Ga-67肿瘤的定量估计 三个主要的误差来源降低了吸收率： 光子散射不完全校正引起的位置相关偏差 和不均匀的衰减，一个大小依赖的偏见，由于模糊的 非平稳检测器响应函数，以及随机变化引起的 从采集的数据中的泊松噪声。 拟议的研究将解决 这些挑战通过（1）优化Ga-67成像的几种方法， 针对患者中的散射和衰减效应校正图像， (2)修改了以前开发的Ga-67 SPECT方法 为了使用先验边界估计感兴趣体积内的活动 来自配准的CT图像的信息，以及（3）设计新的准直器， 为身体成像中Ga-67定量而定制。 的这些方面 成像系统将根据性能进行优化和评估 在几个定量成像任务中。 要考虑的任务， 胸部和腹部肿瘤定量的原型，将涉及 放射性浓度和病灶大小的估计 解剖学上真实的背景。 对于每一项任务，Cramer-Rao 将计算方差或均方误差的下限，以确定 不同校正方法的最佳性能， 最大似然或贝叶斯参数估计将用于测量 最佳实现业绩。 感兴趣的活动量估计 分辨率恢复将用于评估临床可实现 性能 研究人员将通过模拟和幻影测量 实验，在这些任务中的性能的改善，并比较 结果与性能的理论界限。 他们也会考虑 与非霍奇金淋巴瘤相关的临床分类任务。 是 预计拟议的成像系统改进将导致更多的 淋巴瘤患者的准确分期，从而改善患者 护理由于提高能力，以遵循疾病的进展，选择 最好的治疗方法，并监测对治疗的反应。

DESCRIPTION (Adapted from Applicant's Abstract): The goal of the proposed research is to improve the acquisition, reconstruction, and extraction of quantitative information from Ga-67 SPECT data, and to assess these improvements to the imaging system using task-dependent criteria. Gallium has proven to be a useful nuclear medicine tracer for imaging certain tumors, and it is known that gallium avidity is correlated with histopathologic tumor grade. Imaging Ga-67, however, is challenging because it emits many high-energy photons. Quantitative estimates of Ga-67 tumor uptake are degraded by three principal sources of error: a location-dependent bias caused by imperfect correction for photon scatter and nonuniform attenuation, a size-dependent bias due to blurring by the nonstationary detector response function, and stochastic variability arising from Poisson noise in the acquired data. The proposed research will address these challenges by (1) optimizing for Ga-67 imaging several methods of correcting images for the effects of scatter and attenuation in the patient, (2) modifying for Ga-67 SPECT methods that have previously been developed for estimating activity within volumes of interest using a priori boundary information from registered CT images, and (3) designing a new collimator, tailored for Ga-67 quantitation in body imaging. These aspects of the imaging system will be optimized and evaluated on the basis of performance in several quantitative imaging tasks. The tasks to be considered, prototypes of tumor quantitation in the chest and abdomen, will involve estimation of activity concentration and size of lesions located in anatomically realistic backgrounds. For each of these tasks, Cramer-Rao lower bounds on variance or mean-squared error will be computed to determine the best possible performance for different correction methods, while maximum-likelihood or Bayesian parameter estimation will be used to measure best realized performance. Volume-of-interest activity estimation with resolution recovery will be used to assess clinically realizable performance. The investigators will measure, by simulation and phantom experiment, the improvements in performance in these tasks, and compare the results with theoretical bounds on performance. They will also consider clinical classification tasks related to non-Hodgkin s lymphoma. It is expect that the proposed imaging system improvements will lead to more accurate staging of lymphoma patients and, consequently, improved patient care due to enhanced capability to follow the progression of disease, choose the best treatment, and monitor the response to therapy.