European Society of Radiology: Could you please give a detailed overview of when and for which diseases you use cardiac imaging?
Rozemarijn Vliegenthart: Cardiac CT and MRI are increasingly important in the diagnostic and prognostic work-up of cardiac diseases, part of current guidelines, and for some diseases essential for diagnosis. CT and MRI, as a primary imaging method or adjunct to echocardiography, are used in the diagnosis and work-up of coronary artery disease (CAD) (coronary stenosis, myocardial ischaemia, infarction and viability), cardiomyopathy (ischaemic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, non-compaction cardiomyopathy, infiltrative/myocardial storage diseases), myocarditis, cardiac valve disease, cardiac tumours, pericardial disease and congenital heart disease.
ESR: Which modalities are usually used for what?
RV: MRI has become the reference standard for cardiac function and myocardial characterisation. Using Gadolinium late enhancement imaging, the presence and extent of myocardial infarction and non-ischaemic fibrosis can be determined. Prime indications for MRI include evaluation of myocardial viability, cardiomyopathy, and myocarditis. Generally speaking, CT angiography is used for anatomical imaging of the coronary arteries, pulmonary veins, and aortic valve and aorta. The prime indication of CT is the evaluation of CAD, in particular exclusion of coronary stenosis. For aortic valve disease and pericardial disease, CT and MRI yield complementary information. For congenital heart disease, MRI is commonly used, also in the monitoring of patients.
ESR: What is the role of the radiologist within the ‘heart team’? How would you describe the cooperation between radiologists, cardiologists, and other physicians?
RV: The cardiac radiologist has thorough knowledge of, and experience with, non-invasive imaging modalities and techniques. He is a specialist in the imaging diagnostics of both the cardiovascular system and the other organ systems. As a result, he can optimally integrate and weigh up this complex information, whereby self-referral does not play a role. Good cooperation and intensive contact between radiologists and cardiologists are essential (e.g. via cardiology/radiology consultations, multidisciplinary team, grand rounds, etc.). The role of the radiologist in the heart team differs per hospital. Increasingly the radiologist is part of the heart team, but in some hospitals the radiologist is still only invited to illustrate imaging findings in complex cases.
ESR: Radiographers/radiological technologists are also part of the team. When and how do you interact with them?
RV: Radiographers/radiological technologists play an essential, valuable role in the non-invasive cardiac imaging team. Their expertise and experience are crucial for adequate preparation of the patient, acquisition of the cardiac images, and obtaining diagnostic image quality. Also, they sometimes notice findings during image acquisition that influence the subsequent image series to be acquired. During the cardiac CT and MRI programme, there is frequent interaction with the radiographers regarding optimising patient preparation, image acquisition and postprocessing of the acquired data.
ESR: Please describe your regular working environment (hospital, private practice). Does cardiac imaging take up all, most, or only part of your regular work schedule? How many radiologists are dedicated to cardiac imaging in your team?
RV: In the university hospital where I work, there are about three full days of cardiac MRI per week and two full days of cardiac CT. The department is divided into organ-based sections, where cardiovascular and thoracic radiology are combined into one section. This reflects the organ-based organisation of the residency, where cardiothoracic radiology is combined. The team consists of mainly cardiothoracic radiologists, four in total.
ESR: Do you have direct contact with patients and if yes, what is the nature of that contact?
RV: Just like with many other diagnostic radiology areas, contact by the radiologist focuses more on contact with medical specialists, and there is less direct contact with patients. Depending on the local organisation of the department, the cardiac radiologist is involved in administering IV medication to the patient to prepare for the cardiac imaging procedure. In the hospital where I work, the radiologist injects IV betablockers in case of elevated heart rate of the patient, prior to coronary CT angiography. Also, the radiologist administers IV adenosine to induce stress in perfusion MRI (to check for myocardial ischaemia) and records the patient’s blood pressure and heart frequency response and possible complaints during the infusion. The radiologist is often asked to see the patient if any problems occur during or after the examination.
ESR: If you had the means: what would you change in education, training and daily practice in cardiac imaging?
RV: Non-invasive cardiac CT/MRI is not yet performed in all patients who qualify (and can benefit) according to current guidelines. The goal we are working towards in the Netherlands is that in each hospital, a patient can undergo a cardiac CT and MRI for the major indications (in particular coronary artery disease). For this, we need to train more colleagues in cardiac radiology (radiographers and radiologists), set minimal quality standards, and provide support for complex cases. This is a challenging and exciting effort that many colleagues in the cardiovascular section of the Radiological Society of the Netherlands are working at.
ESR: What are the most recent advances in cardiac imaging and what significance do they have for improving healthcare?
RV: In MRI, the role of T1 mapping and T2 mapping is being established. T1, T2 and extracellular volume results are promising in determining the presence and extent of subclinical myocardial fibrosis and oedema, for diagnosis of cardiomyopathy, monitor treatment response and assess prognosis. Mapping helps to detect early stages of disease. For example, T1 mapping is increasingly important in the diagnosis of myocarditis. However, measurement stability at this moment is still a challenge, and more standardisation is needed. Other important developments in MRI include accelerated acquisition techniques, such as compressed sensing. This allows for fast image acquisition in patients who are dyspnoeic or arrhythmic, and reduces artefacts.
In CT, low-radiation, low-contrast coronary imaging has become a new standard, expanding the applicability of CT to lower risk patients, in order to exclude CAD. In case of coronary stenosis, CT is receiving increasing interest as a potential one-stop-shop for evaluation of haemodynamically significant CAD. Two techniques are under investigation: either the addition of a perfusion scan under adenosine stress to detect ischaemia, or the CT-derived evaluation of a fractional flow reserve measurement. Both techniques have shown promising results to increase the specificity of CT for haemodynamically significant CAD, but have not yet been implemented in routine clinical care.
ESR: In what ways has the specialty changed since you started? And where do you see the most important developments in the next ten years?
RV: Over the past ten years the number of indications for cardiac CT and MRI has increased, mainly due to the impressive developments in the capabilities of the modalities as well as new imaging techniques. As an example, with current generation CT systems, diagnostic image quality of the coronary arteries can be obtained at a low radiation dose in nearly all patients irrespective of heart rate and patient size. The number of clinical exam requests has shown an upward trend. Cardiac imaging has become a more established part of mainstream radiology in the Netherlands, and Europe, where cardiac CT and MRI are now included in the general residency curriculum.
ESR: Is artificial intelligence already having an impact on cardiac imaging and how do you see that developing in the future?
RV: Artificial intelligence is receiving a lot of interest, but is currently not yet used in clinical cardiac imaging on a large scale. In the foreseeable future, I expect that AI can derive quantitative imaging parameters from routine cardiac examinations, such as left ventricular function in MRI, and calcium scoring in CT. The final interpretation of the complete cardiac imaging examination remains the realm of the cardiac radiologist, but AI can help in particular by segmenting structures and deriving cardiac measurements.
Prof. Rozemarijn Vliegenthart, MD, PhD, EBCR is a radiologist and tenure track professor at University Medical Center Groningen, the Netherlands. She serves as chairperson of the cardiovascular section of the Radiological Society of the Netherlands, and as secretary of the European Society of Cardiovascular Radiology. Professor Vliegenthart was chairperson of the Cardiac Scientific Subcommittee for ECR 2015, and member cardiac of the Programme Planning Committee for ECR 2018. She is Cardiac Imaging Section Editor of the European Journal of Radiology. Professor Vliegenthart is project leader on large-scale imaging studies in the early detection of cardiothoracic diseases, such as ImaLife and Concrete, and received a number of grants as (co)applicant. She has (co)authored over 160 peer-reviewed articles (H factor 34).