- Email: [email protected]
Advances in Myocardial Perfusion Imaging
PR O G RE S S I N C ARDI O V A S CU L A R D I S EA S E S 5 7 (2 0 1 5) 53 5–5 3 6
Available online at www.sciencedirect.com
ScienceDirect www.onlinepcd.com
Editorial
Advances in Myocardial Perfusion Imaging The first half of the 20th Century was scourged by coronary artery disease (CAD), losing or disabling men and women during the most productive years of their lives. Before the causes of angina were known, therapies for CAD did not exist. In fact, until 1961, the only treatment for patients admitted to hospital with acute myocardial infarction was bed rest, which, in many cases, simply provided the sick with a quiet place, to recover on their own or die silently. The discovery of “CAD risk factors” with the pioneering Framingham Heart Study and the development of treatments against CAD risk factors successfully slowed the progression of atherosclerosis and the resultant death rate. It was imaging, however, that made it possible, for the first time, to visualize coronary atherosclerosis and its effects on myocardial perfusion. Therefore, myocardial perfusion imaging (MPI), at rest and under stress, paved the way for the next groundbreaking advance: the concept of myocardial ischemia from hemodynamically significant obstructive CAD. Revascularization therapy was finally able to target lesions, based on their hemodynamic significance. Noninvasive imaging of myocardial perfusion, illuminated – both metaphorically and literally – the path to tailored management and radically improved clinical outcomes. Soon afterwards, CAD mortalities steeply declined. The burden of CAD risk factors and obstructive coronary atherosclerosis also decreased. Recent data, gleaned from invasive coronary angiography, indicate that, today, a significant proportion (40%) of individuals with angina, have only non-obstructive epicardial coronary atherosclerosis. The frequency of abnormal single photon emission computed tomography (SPECT) MPI has also declined. Yet, over the past few decades, the prevalence of obesity has increased, diabetes remains on the rise, and CAD continues to lead the pack, in terms of causes of death in the United States. Future reductions in CAD mortality and morbidity will, undoubtedly, rely on refinements to MPI to identify not only obstructive, but also non-obstructive CAD, as well as coronary microvascular disease.
Over the past decade, major breakthroughs in imaging technology have significantly enhanced radionuclide MPI, the main stay for the diagnosis and management of CAD. Fundamental improvements have also changed computed tomography (CT), ultrasound and magnetic resonance imaging (MRI) technology, and MPI methods using these technologies. The leading experts, who have contributed to the topics in this issue of Progress in Cardiovascular Diseases, enlighten us all on the specifics of how technological advances over the past decade have transformed MPI. Novel semiconductor detector SPECT scanners, hybrid SPECT and positron emission tomography (PET)/CT scanners, along with several software advances, have richly enhanced image quality while reducing radiation to a fraction of the usual dose. Dr. Slomka and colleagues detail specific imaging methods to perform low radiation dose high quality MPI using novel SPECT and PET scanners. Leveraging the novel scanners to advance MPI though lucrative may require, at present, a large capital investment. Novel radionuclide image reconstruction software fills that gap. Drs. Garcia and Piccinelli elegantly review the advances in resolution recovery, noise reduction, and iterative reconstruction methods to enhance MPI and allow for faster and low radiotracer dose MPI. These software enhancements are integral to the new SPECT and PET scanners. But, if the scanners are not ready for upgrade, with minimal capital investment, these novel software can be fitted to existing scanners to enhance image quality and perform MPI with a low dose of radiotracer. Existing and novel PET radiotracers and their clinical potential are discussed in detail by Dr. Schindler. Some of these tracers may, in the near future, be delivered as unit doses greatly boosting access to PET MPI. These advancements have increased the clinical applications of MPI greatly benefitting the patients with CAD. The clinical application of SPECT, PET, cardiac CT, cardiac MRI, and invasive angiography based measures of MPI is discussed in detail by leading authorities in the field. Drs. Bober and Jahangir critically review the concept of
Financial Disclosures: Dorbala: Research Grant Astellas Global Pharma Development; Dilsizian: Research Grants from GE Healthcare and Siemens.
536
PR O GRE S S I N C ARDI O VAS CU L AR D I S EAS E S 5 7 ( 2 0 15 ) 53 5–5 36
myocardial ischemia and its present day assessment using invasive and noninvasive means, including PET MPI. The paper by Dr. Cuocolo and colleagues lists the factors affecting myocardial blood flow (MBF) and summarizes the literature on flow quantitation with SPECT MPI. This topic is very timely as the novel cardiac SPECT scanners allow tomographic dynamic imaging and flow quantitation. Cardiac MRI is rapidly growing, but, stress imaging is not widely available and is limited by technical expertise. Dr. Michael Jerosh-Herold and colleagues discuss the technical background and advances in quantitative MPI using gadolinium enhanced MR imaging. Dr. Blankstein and colleagues educate us on the power of CT based MPI and fractional flow reserve. This is an exciting area of recent growth that holds promise for combined assessment of coronary atherosclerosis and its effects on MBF with a single study. Dr. DeBruyne and colleagues define the invasive functional indices of ischemia and perfusion and discuss their practical points along with the relevant publications. Finally, Drs. Di Carli and Taqueti provide an overview of the strengths and limitations of radionuclide MBF quantitation in the context of multimodality cardiovascular imaging—a much-needed approach to clinical decision-making. Clearly, MPI has evolved to keep pace with the changing pattern of CAD. Forty years ago, a noninvasive diagnosis of obstructive CAD, the most severe form of disease, was a breakthrough. But, in the 21st Century, we anticipate more from MPI. With advanced imaging, we expect to identify obstructive as well as non-obstructive CAD, and coronary microvascular disease; at a faster pace, with greater precision, and using little to no radiation. As illustrated by the articles in this issue, adaptive practices with the use of innovative technologies will enable this transformation of MPI to further advance the evaluation and management of individuals with suspected and known CAD.
Sharmila Dorbala, MBBS, MPH⁎,1 Noninvasive Cardiovascular Imaging Program Heart and Vascular Center Departments of Radiology and Medicine (Cardiology) Boston, Massachusetts The Division of Nuclear Medicine and Molecular Imaging Department of Radiology, Boston, Massachusetts Brigham and Women’s Hospital, Harvard Medical School Boston, Massachusetts Vasken Dilsizian, MD, FACC, FAHA Department of Diagnostic Radiology and Nuclear Medicine the University of Maryland School of Medicine Baltimore, Maryland The Division of Nuclear Medicine the University of Maryland Medical Center Baltimore, Maryland ⁎Address reprint requests to Sharmila Dorbala, MBBS, MPH Noninvasive Cardiovascular Imaging Program Departments of Radiology and Medicine (Cardiology) Division of Nuclear Medicine and Molecular Imaging Department of Radiology, Brigham and Women’s Hospital, 70 Francis Street, Shapiro 5th Floor, Room 128, Boston, MA 02115 E-mail address: [email protected] 1
Funded by the NIH NHLBI grant K23HL092299
0033-0620 © 2015 Elsevier Inc. All rights reserved.
http://dx.doi.org/10.1016/j.pcad.2015.03.001
Available online at www.sciencedirect.com
ScienceDirect www.onlinepcd.com
Editorial
Advances in Myocardial Perfusion Imaging The first half of the 20th Century was scourged by coronary artery disease (CAD), losing or disabling men and women during the most productive years of their lives. Before the causes of angina were known, therapies for CAD did not exist. In fact, until 1961, the only treatment for patients admitted to hospital with acute myocardial infarction was bed rest, which, in many cases, simply provided the sick with a quiet place, to recover on their own or die silently. The discovery of “CAD risk factors” with the pioneering Framingham Heart Study and the development of treatments against CAD risk factors successfully slowed the progression of atherosclerosis and the resultant death rate. It was imaging, however, that made it possible, for the first time, to visualize coronary atherosclerosis and its effects on myocardial perfusion. Therefore, myocardial perfusion imaging (MPI), at rest and under stress, paved the way for the next groundbreaking advance: the concept of myocardial ischemia from hemodynamically significant obstructive CAD. Revascularization therapy was finally able to target lesions, based on their hemodynamic significance. Noninvasive imaging of myocardial perfusion, illuminated – both metaphorically and literally – the path to tailored management and radically improved clinical outcomes. Soon afterwards, CAD mortalities steeply declined. The burden of CAD risk factors and obstructive coronary atherosclerosis also decreased. Recent data, gleaned from invasive coronary angiography, indicate that, today, a significant proportion (40%) of individuals with angina, have only non-obstructive epicardial coronary atherosclerosis. The frequency of abnormal single photon emission computed tomography (SPECT) MPI has also declined. Yet, over the past few decades, the prevalence of obesity has increased, diabetes remains on the rise, and CAD continues to lead the pack, in terms of causes of death in the United States. Future reductions in CAD mortality and morbidity will, undoubtedly, rely on refinements to MPI to identify not only obstructive, but also non-obstructive CAD, as well as coronary microvascular disease.
Over the past decade, major breakthroughs in imaging technology have significantly enhanced radionuclide MPI, the main stay for the diagnosis and management of CAD. Fundamental improvements have also changed computed tomography (CT), ultrasound and magnetic resonance imaging (MRI) technology, and MPI methods using these technologies. The leading experts, who have contributed to the topics in this issue of Progress in Cardiovascular Diseases, enlighten us all on the specifics of how technological advances over the past decade have transformed MPI. Novel semiconductor detector SPECT scanners, hybrid SPECT and positron emission tomography (PET)/CT scanners, along with several software advances, have richly enhanced image quality while reducing radiation to a fraction of the usual dose. Dr. Slomka and colleagues detail specific imaging methods to perform low radiation dose high quality MPI using novel SPECT and PET scanners. Leveraging the novel scanners to advance MPI though lucrative may require, at present, a large capital investment. Novel radionuclide image reconstruction software fills that gap. Drs. Garcia and Piccinelli elegantly review the advances in resolution recovery, noise reduction, and iterative reconstruction methods to enhance MPI and allow for faster and low radiotracer dose MPI. These software enhancements are integral to the new SPECT and PET scanners. But, if the scanners are not ready for upgrade, with minimal capital investment, these novel software can be fitted to existing scanners to enhance image quality and perform MPI with a low dose of radiotracer. Existing and novel PET radiotracers and their clinical potential are discussed in detail by Dr. Schindler. Some of these tracers may, in the near future, be delivered as unit doses greatly boosting access to PET MPI. These advancements have increased the clinical applications of MPI greatly benefitting the patients with CAD. The clinical application of SPECT, PET, cardiac CT, cardiac MRI, and invasive angiography based measures of MPI is discussed in detail by leading authorities in the field. Drs. Bober and Jahangir critically review the concept of
Financial Disclosures: Dorbala: Research Grant Astellas Global Pharma Development; Dilsizian: Research Grants from GE Healthcare and Siemens.
536
PR O GRE S S I N C ARDI O VAS CU L AR D I S EAS E S 5 7 ( 2 0 15 ) 53 5–5 36
myocardial ischemia and its present day assessment using invasive and noninvasive means, including PET MPI. The paper by Dr. Cuocolo and colleagues lists the factors affecting myocardial blood flow (MBF) and summarizes the literature on flow quantitation with SPECT MPI. This topic is very timely as the novel cardiac SPECT scanners allow tomographic dynamic imaging and flow quantitation. Cardiac MRI is rapidly growing, but, stress imaging is not widely available and is limited by technical expertise. Dr. Michael Jerosh-Herold and colleagues discuss the technical background and advances in quantitative MPI using gadolinium enhanced MR imaging. Dr. Blankstein and colleagues educate us on the power of CT based MPI and fractional flow reserve. This is an exciting area of recent growth that holds promise for combined assessment of coronary atherosclerosis and its effects on MBF with a single study. Dr. DeBruyne and colleagues define the invasive functional indices of ischemia and perfusion and discuss their practical points along with the relevant publications. Finally, Drs. Di Carli and Taqueti provide an overview of the strengths and limitations of radionuclide MBF quantitation in the context of multimodality cardiovascular imaging—a much-needed approach to clinical decision-making. Clearly, MPI has evolved to keep pace with the changing pattern of CAD. Forty years ago, a noninvasive diagnosis of obstructive CAD, the most severe form of disease, was a breakthrough. But, in the 21st Century, we anticipate more from MPI. With advanced imaging, we expect to identify obstructive as well as non-obstructive CAD, and coronary microvascular disease; at a faster pace, with greater precision, and using little to no radiation. As illustrated by the articles in this issue, adaptive practices with the use of innovative technologies will enable this transformation of MPI to further advance the evaluation and management of individuals with suspected and known CAD.
Sharmila Dorbala, MBBS, MPH⁎,1 Noninvasive Cardiovascular Imaging Program Heart and Vascular Center Departments of Radiology and Medicine (Cardiology) Boston, Massachusetts The Division of Nuclear Medicine and Molecular Imaging Department of Radiology, Boston, Massachusetts Brigham and Women’s Hospital, Harvard Medical School Boston, Massachusetts Vasken Dilsizian, MD, FACC, FAHA Department of Diagnostic Radiology and Nuclear Medicine the University of Maryland School of Medicine Baltimore, Maryland The Division of Nuclear Medicine the University of Maryland Medical Center Baltimore, Maryland ⁎Address reprint requests to Sharmila Dorbala, MBBS, MPH Noninvasive Cardiovascular Imaging Program Departments of Radiology and Medicine (Cardiology) Division of Nuclear Medicine and Molecular Imaging Department of Radiology, Brigham and Women’s Hospital, 70 Francis Street, Shapiro 5th Floor, Room 128, Boston, MA 02115 E-mail address: [email protected] 1
Funded by the NIH NHLBI grant K23HL092299
0033-0620 © 2015 Elsevier Inc. All rights reserved.
http://dx.doi.org/10.1016/j.pcad.2015.03.001