PET/MRI of the Heart
Introduction
Before the wide distribution of PET/CT systems, which was mainly owing to their great success in oncology, nuclear cardiology was restricted to SPECT systems. With the broader availability of PET/CT systems, more imaging strategies using different PET tracers such as 18F-FDG for viability or 13N-ammonia (13N-NH3) for perfusion imaging became feasible. Besides the inherent advantages of PET over SPECT such as higher spatial and temporal resolution and higher sensitivity, PET/CT systems with 64-slice (or more) CT components have allowed the combined assessment of metabolic imaging with CT-coronary angiography, which also has resulted in an increased interest in hybrid imaging strategies.1 However, a common āside effectā of hybrid imaging systems is an increased complexity of the workflow, which may result in a higher susceptibility to errors. Owing to the disproportionately higher complexity of MRI when compared with CT, it became clear that this problem might be aggravated for integrated PET/MRI systems. On the contrary, with the advantages of MRI, such as higher soft tissue contrast resolution, the lack of ionizing radiation, and the better tolerable contrast agents, it was generally expected that the positive aspects would outweigh the constraints.
In this review, we aim to discuss cardiac-specific questions. We have given a brief overview on the technical aspects that are relevant for cardiac PET/MRI (eg, implantable devices and workflow). Furthermore, we discuss ātraditionalā cardiovascular applications that we think may profit most from hybrid PET/MRI acquisition (such as myocardial perfusion imaging [MPI] and myocardial tissue characterization) and we refer to current trends and literature on this. Last, we have reviewed certain cardiac diseases and future applications in which PET/MRI may prove a particular benefit.
Section snippets
Technical Aspects
Building an integrated PET/MRI system was hardly considered feasible for a long time, as the high static magnetic field, the rapidly shifting gradient fields, and radiofrequency signals from the MR component disturb the proper operation of conventional photomultiplier tubes and the associated electronics of PET detectors. On the contrary, PET detectors may cause inhomogeneities in magnetic fields and electromagnetic interferences, resulting in a degradation of the MR image quality. To overcome
MPI, T1 Mapping, and Extracellular Volume Quantification
With respect to absolute quantification, one of the major limitations of MR imaging is the lack of clinically relevant information in the measured signal intensities rather than the detection of morphologic contours. MR signal intensities are a function of imaging hardware, pulse sequences, and many other factors, which can produce widely variable results between vendors, field strength, and scanner models. Although in morphologic functional imaging (such as the delineation of dimensions,
Other Potential Applications in Cardiac Molecular Imaging
In the following section, we give an overview of our first experience in distinct disease entities and potential applications for simultaneous cardiac PET/MRI.
Conclusion
PET and MRI are used to represent competing imaging modalities and integration of the two seemed practically impossible for a long time. It is not surprising that the recent advent of PET/MRI made the impression of āa marriage of contrasts.ā Studies with the focus on cardiac imaging evaluating this novel technique are still scarce. The main advantages are reduction of ionizing radiation to the patient, increased patient comfort, possibly a higher patient throughput compared with sequential
Acknowledgments
The preparation of this manuscript would not have been possible without the efforts of many of our staff members. We would like to especially thank Sebastian FĆ¼rst for valuable input and Sylvia Schachoff and Brigitte Dzewas for their technical assistance during PET/MRI acquisitions.
References (90)
- et al.
Determining the risks of magnetic resonance imaging at 1.5 tesla for patients with pacemakers and implantable cardioverter defibrillators
Am J Cardiol
(2012) - et al.
Quantification of absolute myocardial perfusion in patients with coronary artery disease: Comparison between cardiovascular magnetic resonance and positron emission tomography
J Am Coll Cardiol
(2012) - et al.
Assessment of coronary flow reserve: Comparison between contrast-enhanced magnetic resonance imaging and positron emission tomography
J Am Coll Cardiol
(2002) - et al.
First-pass nuclear magnetic resonance imaging studies using gadolinium-DTPA in patients with coronary artery disease
J Am Coll Cardiol
(1991) - et al.
Diagnostic performance of stress cardiac magnetic resonance imaging in the detection of coronary artery disease: A meta-analysis
J Am Coll Cardiol
(2007) - et al.
Feasibility study of myocardial perfusion and oxygenation by noncontrast MRI: Comparison with PET study in a canine model
Magn Reson Imaging
(2008) - et al.
Arterial spin labeled CMR detects clinically relevant increase in myocardial blood flow with vasodilation
JACC Cardiovasc Imaging
(2011) - et al.
A quantitative pixel-wise measurement of myocardial blood flow by contrast-enhanced first-pass CMR perfusion imaging: Microsphere validation in dogs and feasibility study in humans
JACC Cardiovasc Imaging
(2012) - et al.
Quantitative three-dimensional cardiovascular magnetic resonance myocardial perfusion imaging in systole and diastole
J Cardiovasc Magn Reson
(2014) - et al.
Noninvasive quantification of regional blood flow in the human heart using N-13 ammonia and dynamic positron emission tomographic imaging
J Am Coll Cardiol
(1990)
Validation of an axially distributed model for quantification of myocardial blood flow using (1)(3)N-ammonia PET
J Nucl Cardiol
On impulse response functions computed from dynamic contrast-enhanced image data by algebraic deconvolution and compartmental modeling
Phys Med
Myocardial T1 mapping and extracellular volume quantification: A Society for Cardiovascular Magnetic Resonance (SCMR) and CMR Working Group of the European Society of Cardiology consensus statement
J Cardiovasc Magn Reson
F-18-fluorodeoxyglucose positron emission tomography imaging-assisted management of patients with severe left ventricular dysfunction and suspected coronary disease: A randomized, controlled trial (PARR-2)
J Am Coll Cardiol
The extent of perfusion-F18-fluorodeoxyglucose positron emission tomography mismatch determines mortality in medically treated patients with chronic ischemic left ventricular dysfunction
J Am Coll Cardiol
Positron emission tomography and recovery following revascularization (PARR-1): The importance of scar and the development of a prediction rule for the degree of recovery of left ventricular function
J Am Coll Cardiol
Prognostic significance of peripheral monocytosis after reperfused acute myocardial infarction:a possible role for left ventricular remodeling
J Am Coll Cardiol
Impact of heterogeneity of human peripheral blood monocyte subsets on myocardial salvage in patients with primary acute myocardial infarction
J Am Coll Cardiol
++CD16+-->CD14++CD16+ monocytes independently predict cardiovascular events: A cohort study of 951 patients referred for elective coronary angiography
J Am Coll Cardiol
PET/MRI of inflammation in myocardial infarction
J Am Coll Cardiol
Sustained regional abnormalities in cardiac metabolism after transient ischemia in the chronic dog model
J Am Coll Cardiol
Myocardial glucose transporter GLUT1: Translocation induced by insulin and ischemia
J Mol Cell Cardiol
Issues regarding radiation dosage of cardiac nuclear and radiography procedures
J Nucl Cardiol
Serial contrast-enhanced cardiac magnetic resonance imaging demonstrates regression of hyperenhancement within the coronary artery wall in patients after acute myocardial infarction
JACC Cardiovasc Imaging
Radionuclide imaging for the detection of inflammation in vulnerable plaques
J Am Coll Cardiol
18F-fluoride positron emission tomography for identification of ruptured and high-risk coronary atherosclerotic plaques: A prospective clinical trial
Lancet
Diet intervention reduces uptake of alphavbeta3 integrin-targeted PET tracer 18F-galacto-RGD in mouse atherosclerotic plaques
J Nucl Cardiol
PET/CT imaging of integrin alphavbeta3 expression in human carotid atherosclerosis
JACC Cardiovasc Imaging
Noninvasive quantification and optimization of acute cell retention by in vivo positron emission tomography after intramyocardial cardiac-derived stem cell delivery
J Am Coll Cardiol
Low radiation dose imaging of myocardial perfusion and coronary angiography with a hybrid PET/CT scanner
Clin Physiol Funct Imaging
Design and performance evaluation of a whole-body Ingenuity TF PET-MRI system
Phys Med Biol
Performance measurements of the Siemens mMR integrated whole-body PET/MR scanner
J Nucl Med
Performance test of an LSO-APD detector in a 7-T MRI scanner for simultaneous PET/MRI
J Nucl Med
Initial results of simultaneous whole-body ToF PET/MR
J Nucl Med
Do implanted pacemaker leads and ICD leads cause metal-related artifact in cardiac PET/CT?
J Nucl Med
Performing magnetic resonance imaging in patients with implantable pacemakers and defibrillators: Results of a European Heart Rhythm Association survey
Europace
Nuclear imaging in cardiac resynchronization therapy
J Nucl Med
Electrocardiogram-gated 18F-FDG PET/CT hybrid imaging in patients with unsatisfactory response to cardiac resynchronization therapy: Initial clinical results
J Nucl Med
Artifacts from misaligned CT in cardiac perfusion PET/CT studies: Frequency, effects, and potential solutions
J Nucl Med
Frequent diagnostic errors in cardiac PET/CT due to misregistration of CT attenuation and emission PET images: A definitive analysis of causes, consequences, and corrections
J Nucl Med
Three-dimensional late gadolinium enhancement imaging of the left atrium with a hybrid radial acquisition and compressed sensing
J Magn Reson Imaging
Unsupervised inline analysis of cardiac perfusion MRI
Med Image Comput Comput Assist Interv Int
Quantitative assessment of glucose metabolism in the vessel wall of abdominal aortic aneurysms: Correlation with histology and role of partial volume correction
Int J Cardiovasc Imaging
(82)Rb PET myocardial perfusion imaging is superior to (99m)Tc-labelled agent SPECT in patients with known or suspected coronary artery disease
Eur J Nucl Med Mol Imaging
Advances in PET myocardial perfusion imaging: F-18 labeled tracers
Ann Nucl Med
Cited by (53)
Ten things to know about ten imaging studies: A preventive cardiology perspective (āASPC top ten imagingā)
2021, American Journal of Preventive CardiologySimultaneous assessment of coronary flow reserve and left ventricular function during vasodilator stress evaluated by <sup>13</sup>N-ammonia hybrid PET/MRI
2021, Clinical RadiologyCitation Excerpt :The image data matrix was 172 Ć 172 with a pixel size of 3.42 mm and a section thickness of 2.03 mm. Free-breathing cine MRI was performed using an electrocardiography-triggered steady-state free precession cine sequence.17,20 Three standard views were acquired (short-axis view, two-chamber view, and four-chamber view),21 and the section thickness was 5 mm.
Applications of PET-MR Imaging in Cardiovascular Disorders
2020, PET ClinicsCitation Excerpt :The 18F-FDG tracer has a long half-life of approximately 110 minutes. If perfusion is impaired, the uptake of 18F-FDG indicates hibernating myocardium, whereas the absence of 18F-FDG uptake implies infarcted, nonviable tissue.30,31 A metaanalysis of 24 studies and more than 750 patients found sensitivity of 92% and specificity of 63% of PET viability for prediction of regional contractile function recovery after revascularization, although these data are limited by heterogeneous definitions of viability and regional wall motion recovery.32