PET/MR for the multimodal diagnostics of myocardial perfusion: validation and synergies

缺血性心脏病是西方国家最常见的死亡原因。非侵入性诊断可以使用核医学技术进行，如单光子发射断层扫描（SPECT）或正电子发射断层扫描（PET）。动态对比增强心脏磁共振成像也允许诊断，并已被证明具有很高的潜力，临床常规使用。最近，定量灌注测量也获得了很大的兴趣。在核医学检查方面，MRI一方面受益于无电离辐射和显著更高的空间分辨率。另一方面，MRI仍然存在一些主要的缺点，如每个RR间期内只有3到4个切片的解剖覆盖范围相当小，或者验证不理想。因此，在本项目中，将开发新技术，允许在整个心脏覆盖范围内对首过灌注进行高分辨率测量。将使用集成PET/MR系统对这些技术进行确认。除了开发和验证工作的潜力，协同使用的同时获得的PET和MRI数据的心肌组织characterization.The新的成像技术的目的是提供高分辨率的图像，覆盖整个心肌，并允许心肌灌注的定量测定。为了实现全心脏覆盖，将使用同步多层成像（MS-CAIPIRINHA）。除了描述径向k空间轨迹外，还将开发一种成像方法，该方法允许从一次扫描中估计血池和心肌内造影剂浓度的时间曲线。因此，灌注定量将不再需要从prebolus技术中已知的第二次团注，在集成PET/MR系统上实施，新开发的成像技术将得到验证，并将利用同时采集的PET数据评估MS-CAIPIRINHA在准确心肌灌注定量方面的预期优势。MR灌注成像中实现的完整解剖覆盖可以提高与定量PET检查结果的可比性。此外，它将被调查，在何种程度上使用的径向k空间轨迹系统地提高了造影剂quantitation.Considering的MRI造影剂和PET示踪剂的分布动力学的差异，同时采集的PET/MR数据集，预计提供一个组合的一组定量信息的组织功能，超过了信息检索由单独的MRI或PET检查。因此，本项目的目标是评价同步全心脏PET/MR检查在多参数心肌组织定征方面的协同潜力。

Ischemic heart disease is the most common cause of death in western countries. Non-invasively diagnosis can be performed using nuclear medicine techniques like Single Photon Emission Tomography (SPECT) or Positron Emission Tomography (PET). Dynamic contrast enhanced cardiac magnetic resonance imaging also allows for the diagnosis and has demonstrated a high potential for clinical routine use. Recently, also quantitative perfusion measurements gained a lot of interest. With respect to nuclear medicine examinations, MRI on the one hand benefits from the absence of ionizing radiation and the significantly higher spatial resolution. On the other hand MRI still suffers from some major disadvantages like the rather small anatomic coverage of only 3 to 4 slices within each RR-interval or the suboptimal validation.Consequently, in this project new techniques will be developed allowing for highly resolved measurements of the first pass perfusion with whole heart coverage. The techniques will be validated using an integrated PET/MR-system. Besides the development and validation works the potential of a synergetic usage of simultaneously acquired PET and MRI data for myocardial tissue characterization will be explored.The new imaging techniques are intended to provide highly resolved images, cover the whole myocardium and allow for the quantitative determination of the myocardial perfusion. In order to achieve whole heart coverage simultaneous multi-slice imaging (MS-CAIPIRINHA) will be utilized. Incorporating a radial k-space trajectory, additionally an imaging method will be developed that allows estimating the time curves of the contrast agent concentration within the blood pools and the myocardium from one single scan. A second bolus injection as known from the prebolus technique will thus be no longer required for perfusion quantification.Implemented on an integrated PET/MR system, the newly developed imaging techniques will be validated and the expected advantages of MS-CAIPIRINHA in terms of accurate myocardial perfusion quantification will be evaluated utilizing the simultaneously acquired PET data. The achieved full anatomical coverage in MR perfusion imaging allows an improved comparability with the results of the quantitative PET examination. Moreover, it will be investigated, to what extent the use of a radial k-space trajectory systematically improves the contrast agent quantification.Considering the difference in the distribution kinetics for the MRI contrast agent and the PET tracer, a simultaneously acquired PET/MR dataset is expected to deliver a combined set of quantitative information on tissue functionality that exceeds the information retrievable by individual MRI or PET examinations. A goal of this project thus will be to evaluate the synergetic potential of a simultaneous whole heart PET/MR examination regarding a multiparametric myocardial tissue characterization.