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Non-Invasive Cardiac Imaging: Past, Present and Future
HLC 2097 No. of Pages 2
EDITORIAL
Heart, Lung and Circulation (2016) xx, 1–2 1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2016.04.005
Non-Invasive Cardiac Imaging: Past, Present and Future Joseph B. Selvanayagam, MBBS, FRACP, DPhil, FCSANZ, FESC a,b,c* a
Department of Cardiovascular Medicine, Flinders Medical Centre, Bedford Park, Adelaide, Australia Flinders University, Adelaide, Australia South Australian Health & Medical Research Institute (SAHMRI), Adelaide, Australia
b c
Keywords
Echocardiography Magnetic resonance imaging Cardiac imaging Cardiac CT Nuclear cardiology
Echocardiography, Nuclear imaging, Cardiovascular Magnetic Resonance (CMR) and Cardiac CT (CCT), are now integral parts of cardiovascular care, impacting greatly on patient diagnosis, management and prognosis. All of these imaging modalities have made significant strides in technical and clinical development over the last quarter of a century, and in the case of CMR and CCT, these evolutionary steps have been particularly striking. Twenty-five years ago, as this Journal was launched, echocardiography, in the form of 2Dechocardiography and transoesophageal echocardiography, was already established as a robust and essential clinical tool in the assessment of cardiac patients. Similarly, nuclear cardiology, established in the 1980’s with the design of specific radiopharmaceuticals for cardiac use, was already being used for the assessment of left ventricular function and myocardial ischaemia. Indeed, in one of the first original papers published in the Journal, Buxton and colleagues assessed 57 patients undergoing CABG with preoperative radionucleotide LV functional testing and thallium exercise testing for myocardial ischaemia [1]. Patients were followedup for a median of 20 months postoperatively with assessment of mortality and change in LVEF at 12 months as the primary outcome. They found that, ‘‘fixed ischaemia on thallium study appeared to be associated with poor survival and deterioration of LV function’’. This was an important early finding on the utility of viability testing pre CABG in this population. Perhaps the greatest strides in cardiac imaging in the last quarter of century have been in the areas of CCT and CMR. These were essentially non-existent as clinical modalities in the last millennium but are now mainstream in routine
clinical care. The heart had long escaped high-resolution detection by MRI and CT, because it is a constantly moving structure, posing a number of additional technical challenges to its detection. Cardiac magnetic resonance has come to fruition only since the mid 1990’s, due to major advances in hardware design (high-field, highly homogenous magnets), coil design, sequence development, vector ECG and computing power. The latter has been instrumental in speeding up image reconstruction and post-processing, a previously critical bottleneck in both CMR and CCT. Computer tomographic coronary angiography now provides excellent image quality at low to extremely low effective radiation doses, which, coupled with ongoing progress in scanner technology and accumulating clinical trial evidence, establishes CT as a core technology for cardiovascular patient care. Beyond CT angiography, the technique now provides detailed assessment of the arterial wall, left ventricular (LV) and systolic function, and evaluation of coronary physiology with perfusion imaging and CT-FFR. Cardiac magnetic resonance permits concurrent 3D assessment of LV global and regional function, RV function, myocardial perfusion, viability and flow with high accuracy and reproducibility. It ‘stands alone’ as the imaging technique of choice for myocardial tissue characterisation, in the assessment of oedema, necrosis, replacement fibrosis, diffuse fibrosis, iron and haemorrhage. The significant growth in the cardiac imaging field was highlighted in the March 2010 issue of the journal, edited by Drs Allman and McCrohan [2]. Internationally recognised cardiac imaging experts based both locally and overseas were asked to contribute review articles on important
*Corresponding author at: Department of Cardiovascular Medicine, Flinders Medical Centre & Flinders University, Flinders Drive, Bedford Park, Adelaide, South Australia 5043, Australia, Email: [email protected] © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B. V. All rights reserved.
Please cite this article in press as: Selvanayagam JB. Non-Invasive Cardiac Imaging: Past, Present and Future. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.04.005
HLC 2097 No. of Pages 2
2
J.B. Selvanayagam
current and emerging topics across all modalities. Articles on echocardiographic strain imaging, high field strength CMR imaging, CCT clinical applications, Cardiac MR Spectroscopy and utility of nuclear imaging in evaluation of restorative cardiac therapies [3–7], not only highlighted the tremendous strides in the imaging field, but also the international training exposure of Australian/NZ imagers. Dr Beller’s article on the ‘‘Recent advances and future trends in multimodality cardiac imaging’’ is particularly prescient six years after publication [8]. As he predicted, both ‘‘Multimodality imaging’’ (in which two different types of images of the cardiovascular system are obtained either serially or simultaneously) and fusion imaging (in which two disparate image datasets are merged into one functional image), have expanded in recent years, especially in relation to CT-PET and PET-MR systems. Cardiac CT-PET systems have the capability to fuse vessel anatomy from computed tomography coronary angiography with an area of reduced regional blood flow on a myocardial perfusion PET or SPECT scan. Similar to CT-FFR, when combining both anatomical and functional imaging, CT-PET/SPECT have been shown to be superior to CCT alone in predicting significant coronary artery disease although at the cost of slightly increased radiation [9]. Furthermore, they permit revascularisation decisions to be made from a ‘one stop shop’ imaging test without the need for a second, invasive or non-invasive test. The rapid growth of cardiac imaging is a classic ‘good news/bad news’ scenario. Improvements in hardware and software permit rapid, accurate and reproducible assessment of cardiac anatomy and physiology without the need for invasive testing or operative intervention. It is now possible to investigate any patient with cardiovascular disease via a host of non-invasive techniques that vary in technical requirements, benefits, limitations and costs. However, challenges remain. With increasing sophistication of imaging techniques, training of both physician and technologist and appropriate credentialling are important. In the era of the shrinking healthcare dollar, it behoves the field to show not just sensitivity and specificity, but also comparative health effectiveness of various imaging strategies and meaningful impact on patient care. For example, in the current
funding environment it is unlikely that a new imaging test will be accepted for reimbursement even if showing high diagnostic accuracy for a particular disease process, if comparative effectiveness and health outcomes are not also shown. In order for an imaging test to influence outcomes, trials in which patient treatment algorithms are defined by the results of these tests are essential [10]. In the next 25 years, it is crucial that the inevitable technical advances in imaging are paralleled, or even exceeded by, the expansion of the evidence base to evaluate the comparative cost-effectiveness of imaging-based decision-making on clinical outcomes, quality of life, cost effectiveness, and downstream resource utilisation.
References [1] Buxton B, Royse A, Pornvilawan S, Raman J, Sia B, Horowitz J. Coronary artery bypass in patients with poor left ventricular function: Reversible vs irreversible ischaemia. Asia Pacific Journal of Thoracic & Cardiovascular Surgery 1994;3(1):43–4. [2] Allman Kevin Cvn, McCrohon Jane An , editors. Advances in medical imaging. Heart Lung Circ 2010;19(3):105–210. [3] Leung Dominic Y, Ng Arnold CT. Emerging clinical role of strain imaging in echocardiography. Heart Lung Circ 2010;19(3):161–74. [4] Cheng Adrian SH, Selvanayagam Joseph B. High field cardiac magnetic resonance imaging – current and future perspectives. Heart Lung Circ 2010;19(3):145–53. [5] de Graaf FR, Schuijf JD, Delgado V, van Velzen JE, Kroft LJ, de Roos A. Clinical application of ct coronary angiography: state of the art. Heart Lung Circ 2010;19(3):107–16. [6] Bohl Steffen, Schulz-Menger Jeanette. Cardiovascular magnetic resonance imaging of non-ischaemic heart disease: established and emerging applications. Heart Lung Circ 2010;19(3):117–32. [7] Fukushima Kenji, Higuchi Takahiro, Bengel Frank M. Nuclear imaging in the evaluation of clinical restorative cardiac therapies. Heart, Lung, Circ 2010;19(3):185–92. [8] Beller George A. Recent advances and future trends in multimodality cardiac imaging. Heart Lung Circ 2010;19(3):193–209. [9] Liga R, Vontobel J, Rovai D, Marinelli M, Caselli C, Pietila M, et al. Multicentre multi-device hybrid imaging study of coronary artery disease: results from the EValuation of INtegrated Cardiac Imaging for the Detection and Characterization of Ischaemic Heart Disease (EVINCI) hybrid imaging population. 2016, Eur Heart J Cardiovasc Imaging 2016;(Mar 18). pii: jew038. [10] Selvanayagam JB, Prasad S, McGavigan AD, Hillis G, Jung W, Krum H. Cardiovascular Magnetic Resonance GUIDEd management of mildmoderate left ventricular systolic Heart Failure (CMR GUIDE HF): study protocol for a randomized controlled trial. J Cardiovasc Magn Reson 2015;17(Suppl 1). http://dx.doi.org/10.1186/1532-429X.
Please cite this article in press as: Selvanayagam JB. Non-Invasive Cardiac Imaging: Past, Present and Future. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.04.005
EDITORIAL
Heart, Lung and Circulation (2016) xx, 1–2 1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2016.04.005
Non-Invasive Cardiac Imaging: Past, Present and Future Joseph B. Selvanayagam, MBBS, FRACP, DPhil, FCSANZ, FESC a,b,c* a
Department of Cardiovascular Medicine, Flinders Medical Centre, Bedford Park, Adelaide, Australia Flinders University, Adelaide, Australia South Australian Health & Medical Research Institute (SAHMRI), Adelaide, Australia
b c
Keywords
Echocardiography Magnetic resonance imaging Cardiac imaging Cardiac CT Nuclear cardiology
Echocardiography, Nuclear imaging, Cardiovascular Magnetic Resonance (CMR) and Cardiac CT (CCT), are now integral parts of cardiovascular care, impacting greatly on patient diagnosis, management and prognosis. All of these imaging modalities have made significant strides in technical and clinical development over the last quarter of a century, and in the case of CMR and CCT, these evolutionary steps have been particularly striking. Twenty-five years ago, as this Journal was launched, echocardiography, in the form of 2Dechocardiography and transoesophageal echocardiography, was already established as a robust and essential clinical tool in the assessment of cardiac patients. Similarly, nuclear cardiology, established in the 1980’s with the design of specific radiopharmaceuticals for cardiac use, was already being used for the assessment of left ventricular function and myocardial ischaemia. Indeed, in one of the first original papers published in the Journal, Buxton and colleagues assessed 57 patients undergoing CABG with preoperative radionucleotide LV functional testing and thallium exercise testing for myocardial ischaemia [1]. Patients were followedup for a median of 20 months postoperatively with assessment of mortality and change in LVEF at 12 months as the primary outcome. They found that, ‘‘fixed ischaemia on thallium study appeared to be associated with poor survival and deterioration of LV function’’. This was an important early finding on the utility of viability testing pre CABG in this population. Perhaps the greatest strides in cardiac imaging in the last quarter of century have been in the areas of CCT and CMR. These were essentially non-existent as clinical modalities in the last millennium but are now mainstream in routine
clinical care. The heart had long escaped high-resolution detection by MRI and CT, because it is a constantly moving structure, posing a number of additional technical challenges to its detection. Cardiac magnetic resonance has come to fruition only since the mid 1990’s, due to major advances in hardware design (high-field, highly homogenous magnets), coil design, sequence development, vector ECG and computing power. The latter has been instrumental in speeding up image reconstruction and post-processing, a previously critical bottleneck in both CMR and CCT. Computer tomographic coronary angiography now provides excellent image quality at low to extremely low effective radiation doses, which, coupled with ongoing progress in scanner technology and accumulating clinical trial evidence, establishes CT as a core technology for cardiovascular patient care. Beyond CT angiography, the technique now provides detailed assessment of the arterial wall, left ventricular (LV) and systolic function, and evaluation of coronary physiology with perfusion imaging and CT-FFR. Cardiac magnetic resonance permits concurrent 3D assessment of LV global and regional function, RV function, myocardial perfusion, viability and flow with high accuracy and reproducibility. It ‘stands alone’ as the imaging technique of choice for myocardial tissue characterisation, in the assessment of oedema, necrosis, replacement fibrosis, diffuse fibrosis, iron and haemorrhage. The significant growth in the cardiac imaging field was highlighted in the March 2010 issue of the journal, edited by Drs Allman and McCrohan [2]. Internationally recognised cardiac imaging experts based both locally and overseas were asked to contribute review articles on important
*Corresponding author at: Department of Cardiovascular Medicine, Flinders Medical Centre & Flinders University, Flinders Drive, Bedford Park, Adelaide, South Australia 5043, Australia, Email: [email protected] © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B. V. All rights reserved.
Please cite this article in press as: Selvanayagam JB. Non-Invasive Cardiac Imaging: Past, Present and Future. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.04.005
HLC 2097 No. of Pages 2
2
J.B. Selvanayagam
current and emerging topics across all modalities. Articles on echocardiographic strain imaging, high field strength CMR imaging, CCT clinical applications, Cardiac MR Spectroscopy and utility of nuclear imaging in evaluation of restorative cardiac therapies [3–7], not only highlighted the tremendous strides in the imaging field, but also the international training exposure of Australian/NZ imagers. Dr Beller’s article on the ‘‘Recent advances and future trends in multimodality cardiac imaging’’ is particularly prescient six years after publication [8]. As he predicted, both ‘‘Multimodality imaging’’ (in which two different types of images of the cardiovascular system are obtained either serially or simultaneously) and fusion imaging (in which two disparate image datasets are merged into one functional image), have expanded in recent years, especially in relation to CT-PET and PET-MR systems. Cardiac CT-PET systems have the capability to fuse vessel anatomy from computed tomography coronary angiography with an area of reduced regional blood flow on a myocardial perfusion PET or SPECT scan. Similar to CT-FFR, when combining both anatomical and functional imaging, CT-PET/SPECT have been shown to be superior to CCT alone in predicting significant coronary artery disease although at the cost of slightly increased radiation [9]. Furthermore, they permit revascularisation decisions to be made from a ‘one stop shop’ imaging test without the need for a second, invasive or non-invasive test. The rapid growth of cardiac imaging is a classic ‘good news/bad news’ scenario. Improvements in hardware and software permit rapid, accurate and reproducible assessment of cardiac anatomy and physiology without the need for invasive testing or operative intervention. It is now possible to investigate any patient with cardiovascular disease via a host of non-invasive techniques that vary in technical requirements, benefits, limitations and costs. However, challenges remain. With increasing sophistication of imaging techniques, training of both physician and technologist and appropriate credentialling are important. In the era of the shrinking healthcare dollar, it behoves the field to show not just sensitivity and specificity, but also comparative health effectiveness of various imaging strategies and meaningful impact on patient care. For example, in the current
funding environment it is unlikely that a new imaging test will be accepted for reimbursement even if showing high diagnostic accuracy for a particular disease process, if comparative effectiveness and health outcomes are not also shown. In order for an imaging test to influence outcomes, trials in which patient treatment algorithms are defined by the results of these tests are essential [10]. In the next 25 years, it is crucial that the inevitable technical advances in imaging are paralleled, or even exceeded by, the expansion of the evidence base to evaluate the comparative cost-effectiveness of imaging-based decision-making on clinical outcomes, quality of life, cost effectiveness, and downstream resource utilisation.
References [1] Buxton B, Royse A, Pornvilawan S, Raman J, Sia B, Horowitz J. Coronary artery bypass in patients with poor left ventricular function: Reversible vs irreversible ischaemia. Asia Pacific Journal of Thoracic & Cardiovascular Surgery 1994;3(1):43–4. [2] Allman Kevin Cvn, McCrohon Jane An , editors. Advances in medical imaging. Heart Lung Circ 2010;19(3):105–210. [3] Leung Dominic Y, Ng Arnold CT. Emerging clinical role of strain imaging in echocardiography. Heart Lung Circ 2010;19(3):161–74. [4] Cheng Adrian SH, Selvanayagam Joseph B. High field cardiac magnetic resonance imaging – current and future perspectives. Heart Lung Circ 2010;19(3):145–53. [5] de Graaf FR, Schuijf JD, Delgado V, van Velzen JE, Kroft LJ, de Roos A. Clinical application of ct coronary angiography: state of the art. Heart Lung Circ 2010;19(3):107–16. [6] Bohl Steffen, Schulz-Menger Jeanette. Cardiovascular magnetic resonance imaging of non-ischaemic heart disease: established and emerging applications. Heart Lung Circ 2010;19(3):117–32. [7] Fukushima Kenji, Higuchi Takahiro, Bengel Frank M. Nuclear imaging in the evaluation of clinical restorative cardiac therapies. Heart, Lung, Circ 2010;19(3):185–92. [8] Beller George A. Recent advances and future trends in multimodality cardiac imaging. Heart Lung Circ 2010;19(3):193–209. [9] Liga R, Vontobel J, Rovai D, Marinelli M, Caselli C, Pietila M, et al. Multicentre multi-device hybrid imaging study of coronary artery disease: results from the EValuation of INtegrated Cardiac Imaging for the Detection and Characterization of Ischaemic Heart Disease (EVINCI) hybrid imaging population. 2016, Eur Heart J Cardiovasc Imaging 2016;(Mar 18). pii: jew038. [10] Selvanayagam JB, Prasad S, McGavigan AD, Hillis G, Jung W, Krum H. Cardiovascular Magnetic Resonance GUIDEd management of mildmoderate left ventricular systolic Heart Failure (CMR GUIDE HF): study protocol for a randomized controlled trial. J Cardiovasc Magn Reson 2015;17(Suppl 1). http://dx.doi.org/10.1186/1532-429X.
Please cite this article in press as: Selvanayagam JB. Non-Invasive Cardiac Imaging: Past, Present and Future. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.04.005