Abstract
BackgroundPET-MR scanners are beginning to be employed for quantitative myocardial perfusion imaging. In order to examine simultaneous perfusion calculations, this work describes a feasibility study of simultaneous PET-MR of gadolinium-based contrast agent (GBCA) and PET radiotracer in a novel cardiac perfusion phantom.Results[18F]F− and GBCA were injected simultaneously into a cardiac phantom using a range of ground-truth myocardial perfusion rates of 1 to 5 ml/g/min. PET quantification of K1 (ml/g/min) was performed using a single tissue compartment model. MR perfusion was calculated using a model-independent signal deconvolution technique. PET and MR signal traces from the phantom aorta and myocardial sections show true simultaneous PET and MR arterial input functions (AIF) and myocardial uptake respectively at each perfusion rate. Calculation of perfusion parameters showed both K1 and h(t = 0) (PET and MR perfusion parameters respectively) to be linearly related with the ground truth perfusion rate (PT), and also linearly related to each other (R2 = 0.99). The highest difference in perfusion values between K1 and PT was 16% at 1 ml/g/min, and the mean difference for all other perfusion rates was <3%.ConclusionsThe perfusion phantom allows accurate and reproducible simulation of the myocardial kinetics for simultaneous PET-MR imaging, and may find use in protocol design and development of PET-MR based quantification techniques and direct comparison of quantification of the two modalities.
Highlights
Positron emission tomography & magnetic resonance (PET-MR) scanners are beginning to be employed for quantitative myocardial perfusion imaging
The expected gadolinium-based contrast agent (GBCA) and Positron emission tomography-computed tomography (PET) radiotracer distribution through the phantom can be seen at increasing time points of the 2D MR imaging sequence and fused PET-MR images detailing the first pass dynamics of the phantom
As the repeat injection of [18F]F− and GBCA was performed using the same timings and methodology as the first test, the time traces produced by both PET and MR data were similar
Summary
PET-MR scanners are beginning to be employed for quantitative myocardial perfusion imaging. Results: [18F]F− and GBCA were injected simultaneously into a cardiac phantom using a range of ground-truth myocardial perfusion rates of 1 to 5 ml/g/min. PET and MR signal traces from the phantom aorta and myocardial sections show true simultaneous PET and MR arterial input functions (AIF) and myocardial uptake respectively at each perfusion rate. Cardiac magnetic resonance (CMR) plays an increasing role in the diagnosis and stratification of patients with suspected coronary artery disease (CAD) justified by its high spatial resolution, tissue contrast and the ability to provide reproducible quantitative data on parameters such as left ventricular volumes and mass. Positron emission tomography-computed tomography (PET) imaging is a highly accurate method for assessment of obstructive coronary artery disease (CAD), with a sensitivity and specificity of approximately 90% (Di Carli et al, 2007) and is considered the reference method for non-invasive quantification of myocardial perfusion (Bengel et al, 2009). The combination of PET and MR acquisitions can provide further benefits in cardiac imaging such as real-time motion correction (Petibon et al, 2013), reduced patient scan time compared to independent CMR and PET-CT scans (Ratib & Nkoulou, 2014), and a reduction in exposure to ionizing radiation (Ratib et al, 2013)
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