Velasco Carlos, Mota-Cobián Adriana, Mateo Jesús, España Samuel
Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.
Departamento de Estructura de la Materia, Física Térmica y Electrónica, Facultad de Ciencias Físicas, Ciudad Universitaria, Universidad Complutense de Madrid, IdISSC, 28040, Madrid, Spain.
EJNMMI Phys. 2020 Feb 6;7(1):7. doi: 10.1186/s40658-020-0277-4.
Conventional PET imaging has usually been limited to a single tracer per scan. We propose a new technique for multi-tracer PET imaging that uses dynamic imaging and multi-tracer compartment modeling including an explicitly derived arterial input function (AIF) for each tracer using blood sampling spectroscopy. For that purpose, at least one of the co-injected tracers must be based on a non-pure positron emitter.
The proposed technique was validated in vivo by performing cardiac PET/CT studies on three healthy pigs injected with FDG (viability) and Ga-DOTA (myocardial blood flow and extracellular volume fraction) during the same acquisition. Blood samples were collected during the PET scan, and separated AIF for each tracer was obtained by spectroscopic analysis. A multi-tracer compartment model was applied to the myocardium in order to obtain the distribution of each tracer at the end of the PET scan. Relative activities of both tracers and tracer uptake were obtained and compared with the values obtained by ex vivo analysis of excised myocardial tissue segments.
A high correlation was obtained between multi-tracer PET results, and those obtained from ex vivo analysis (FDG relative activity: r = 0.95, p < 0.0001; SUV: r = 0.98, p < 0.0001).
The proposed technique allows performing PET scans with two tracers during the same acquisition obtaining separate information for each tracer.
传统的正电子发射断层显像（PET）成像通常每次扫描仅限于使用一种示踪剂。我们提出了一种用于多示踪剂PET成像的新技术，该技术使用动态成像和多示踪剂房室模型，包括通过血液采样光谱法为每种示踪剂明确推导的动脉输入函数（AIF）。为此，至少一种共注射的示踪剂必须基于非纯正电子发射体。
通过对三只健康猪进行心脏PET/CT研究来对所提出的技术进行体内验证，在同一采集过程中注射氟代脱氧葡萄糖（FDG，用于评估存活能力）和镓-多胺多羧基配合物（Ga-DOTA，用于评估心肌血流和细胞外容积分数）。在PET扫描期间采集血样，并通过光谱分析获得每种示踪剂单独的AIF。将多示踪剂房室模型应用于心肌，以获得PET扫描结束时每种示踪剂的分布。获得两种示踪剂的相对活性和示踪剂摄取，并与通过对切除的心肌组织段进行离体分析获得的值进行比较。
多示踪剂PET结果与离体分析结果之间具有高度相关性（FDG相对活性：r = 0.95，p < 0.0001；标准化摄取值：r = 0.98，p < 0.0001）。
所提出的技术允许在同一采集过程中使用两种示踪剂进行PET扫描，从而为每种示踪剂获取单独的信息。
