European Society of Radiology: Could you please give a detailed overview of when and for which diseases you use cardiac imaging?
Julie O’Brien: In my practice, cardiac imaging includes cardiac computed tomography (CT) and cardiac magnetic resonance imaging (CMR). Nuclear cardiac imaging is performed very rarely in our department.
Due to its excellent spatial resolution, the majority of cardiac CTs are performed to evaluate coronary arteries, including stents and bypass grafts. It is also used in structural heart disease as well as evaluation of the aorta.
CMR takes advantage of its excellent tissue characterisation and is used to evaluate the myocardium.
In addition, cine imaging is used to calculate ejection fraction and wall motion.
Phase contrast imaging is used to assess for velocity across valves, conduits such as in the setting of congenital heart disease and across vessel stenoses.
ESR: Which modalities are usually used for what?
JO’B: CT with its very high spatial resolution is widely used for the evaluation of coronary arteries. It is also used for evaluation of cardiac structures and aorta, particularly for pre-procedure and pre-device planning such as left atrial appendage closure devices and prior to pulmonary vein ablation.
There has been huge growth in TAVI (transcatheter aortic valve implantation) and CT plays a very important role in pre-procedure planning for both the valve size as well as evaluating other important parameters such as coronary artery height. In addition, it provides details of the peripheral vasculature to provide information to guide optimal access.
Transcatheter mitral valve intervention is now being performed which also requires CT for procedure planning.
Given the huge advances in technology, low dose CT scanning is now feasible with good quality images, which has led the way for CT evaluation of congenital heart disease with excellent detail.
CMR has numerous indications owing to its excellent tissue characterisation. It is the gold standard for calculation of LV ejection fraction and widely used for the evaluation of heart failure and myocardial disease. It plays a very central role in the diagnosis and prognosis of conditions such as hypertrophic cardiomyopathy and other causes of sudden cardiac death.
The administration of contrast at CMR provides differentiation between normal and diseased myocardium with the use of gadolinium-based contrast agents and special magnetic resonance pulse sequences also called LGE. Patterns of LGE can assist with diagnosis of certain conditions, as well as provide prognostic information in some cases. In addition, LGE can provide a target for cardiac biopsy.
Phase contrast CMR techniques measure velocity in the phase of the directed signal. This plays an important role in the evaluation of valvular disease, used to calculated severity. In addition, it is used to evaluate conduits and baffles in the setting of congenital heart disease as well and vascular stenoses such as coarctation and pulmonary arterial stenoses.
Stress CMR is used for the detection of coronary artery disease (CE-MARC) as well as to assess both diffuse myocardial ischaemia and microvascular dysfunction.
Pericardial disease can be evaluated on both CT and CMR depending on the clinical setting. CMR can provide real-time, free breathing cine imaging to demonstrate septal excursion in the setting of constrictive physiology.
ESR: What is the role of the radiologist within the ‘heart team’? How would you describe the cooperation between radiologists, cardiologists, and other physicians?
JO’B: The radiologist plays a very important role in the ‘heart team’ as in all multi-disciplinary teams.
Our experience with imaging techniques and knowledge of anatomy is invaluable in the interpretation of the findings, however, this needs to be integrated with clinical information from our cardiology colleagues to provide the correct diagnosis and facilitate optimal patient outcomes.
In addition, radiologists have a lot of experience with regard to the management of extra-cardiac findings which is an important consideration in every cardiac imaging service.
The combined approach is also optimal for teaching and research opportunities.
ESR: Radiographers/radiological technologists are also part of the team. When and how do you interact with them?
JO’B: Radiographers are a vital part of the team because good quality images are the key to providing high-quality accurate reports. In our busy general department, we work very closely with our radiography colleagues daily.
I have collaborated with some of them on research projects which they have found very interesting and which has given them an opportunity to become more specialised in the technique.
We are very fortunate that there will be a specific two-day course for radiographers at the upcoming Society of Cardiovascular Computed Tomography (SCCT) Winter meeting in Dublin 2019 which I hope some of my radiographer colleagues will get the opportunity to attend.
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?
JO’B: The teaching hospital where I work is a Model 4 hospital for the Mid-Western hospital group.
The majority of my workload involves general radiology, including oncology and trauma as well as acute medicine and surgery. Cardiac imaging is currently a small part of the workload, however, with the introduction of new equipment and training, we are building the service and hope that it will continue to expand.
There are currently two level III fellowship trained radiologists running the service.
We are fortunate to have a great working relationship with our cardiology colleagues who are keen to expand the service and collaborate with research.
ESR: Do you have direct contact with patients and if yes, what is the nature of that contact?
JO’B: I have regular contact with patients in the general working environment of the radiology department. In terms of cardiac imaging, this includes supervising the rate controlling and if there is an issue raised by the pre-examination questionnaire.
If patients have a question or concern about the study, I am the one who speaks to them.
ESR: If you had the means: what would you change in education, training and daily practice in cardiac imaging?
JO’B: The Faculty of Radiologists are currently updating the Final Fellowship (FFR) curriculum which will include the development of the cardiac imaging curriculum which is an exciting opportunity. In my opinion, radiology trainees should at least be level I trained if not level II by the time they finish their general training. This is something I am very keen to develop.
We are very fortunate that the SCCT Winter meeting will be held in Dublin January 2019 which will be a great opportunity for cardiologists and radiologists in Ireland to meet and hear experts in the field of cardiac CT, which is something I am keen to promote among the cardiac imaging community in Ireland.
I am grateful that I have a great relationship with the British Society of Cardiovascular Imaging and British Society of Cardiac CT (BSCI/BSCCT) which have recently provided level 1 cardiac CT teaching in Ireland. I have been co-opted onto the committee and I hope this will be mutually beneficial for us going forward to develop the discipline.
In my own daily practice, cardiac CT is linked to the acute chest pain unit, but I would like to see the development of a formal chest pain pathway in the near future. I also hope to expand the programme, to support the growing cardiology service in our hospital including TAVI and other devices and well as pre-ablation studies.
If I had the means, I would be very keen to develop our research group. We are fortunate that our colleagues at the University of Limerick have a lot of expertise, as well as our progressive cardiology colleagues, which is a great opportunity that I feel we must support.
In terms of cardiac MRI, the biggest limitation, particularly in acute hospitals, is access to the MRI scanner. If I had the means, I would really like to provide adequate access to provide a complete and high-level service. This would be of huge benefit to patients and would provide a significant improvement in education and training.
ESR: What are the most recent advances in cardiac imaging and what significance do they have for improving healthcare?
JO’B: There have been many advances in technology over the past number of years, including CT scanner technology and post-processing software which has improved our clinical delivery of the service.
The possibility of providing functional data as well as anatomic data on the same study is something that holds the promise of reducing healthcare costs by reducing hospital stays, cutting the number of tests and speeding patient diagnosis, a type of ‘one stop shop’ study.
CT perfusion has been developed to provide this information, but it has been limited by artefact and radiation dose.
CT-FFR (fractional flow reserve) is another technique developed to provide functional information about a coronary stenosis on a static CT study without performing any extra scanning. The background to this is that FFR is a measurement currently performed by pressure wire technique during catheter angiography to measure pressure differences across a coronary artery stenosis to determine the likelihood that the stenosis results in myocardial ischaemia.
The development of CT-FFR, a non-invasive measurement utilising advanced computational analytic approaches, enables combined anatomic and haemodynamic assessment of a coronary lesion by a single non-invasive test.
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?
JO’B: Low dose CT scanning is a very important advancement, which has been due to multiple factors such as faster scanners, prospective imaging, and iterative reconstruction techniques which is now standard of care. This has provided safe, high-quality imaging for patients. As a result, CT scanning has become more widespread and as research has shown, in many studies cardiac CT has been proven to improve outcomes.
There has been an explosion of cardiovascular research in the last ten years, including registries and randomised control trials, which has provided us with high-level evidence for many guidelines and information on prognosis.
CT has become central to pre-procedure and pre-device planning. 3D printing is now widely used in pre-procedure preparation.
In terms of cardiac MRI, the biggest advances in the last decade have been the introduction of T1 and T2 mapping, and extracellular volume fraction (ECV) to provide further tissue characterisation particularly in the evaluation of cardiomyopathies.
The most important developments in the next ten years will be in precision medicine and artificial intelligence. ‘Precision medicine’ is a term used to potentially provide personalised and efficient diagnostics and treatment decisions due to the increasing wealth of patient-related health data. The current issue is that health data such as clinical, imaging, lab, pathology, or genomics data is stored on different systems which are poorly integrated.
Integrated decision support tools that collate this information on a unified platform could ease workflows and help choose the best investigation and treatment options for individual patients. This has shown great potential for the investigation and treatment of patients with cardiovascular disease.
Artificial intelligence (AI) involves machines that can perform tasks that are characteristic of human intelligence. This includes characteristics like planning, understanding language, recognising objects and sounds, learning, and problem-solving.
Machine learning is a method of achieving AI, by ‘training’ an algorithm so that it can learn by experience.
ESR: So how do you see artificial intelligence developing in the future?
JO’B: I am not an expert on this topic, but it is known that artificial intelligence and machine learning have the potential to influence nearly every aspect of the human condition. In the field of medicine, it promises to provide the tools to augment and extend the effectiveness of clinicians.
It is already part of healthcare delivery, particularly in oncology.
Artificial intelligence has the potential to generate more accurate and personalised diagnoses as well as risk metrics. It is likely it will affect all aspects of patient care in cardiovascular medicine, from research and development to diagnosis to selection of therapy as well as population health.
Dr. Julie O’Brien is a Consultant Radiologist in University Hospital Limerick and Adjunct Senior Clinical Lecturer at the University of Limerick, Ireland. She obtained her medical degree from University College Dublin.
Following her radiology training, she completed three subspecialty fellowships in Vancouver, Canada, including cardiac imaging with Dr. Jonathon Leipsic.
Dr. O’Brien is the current Chair of the cardiac imaging subcommittee of the Faculty of Radiologists in Ireland and is a co-opted member of the committee of the BSCI/BSCCT. She was recently awarded FSCCT and is on the local organising committee for the SCCT Winter meeting Dublin 2019.