European Society of Radiology: Could you please give a detailed overview of when and for which diseases you use cardiac imaging?
Harold Goerne: Non-invasive cardiac imaging plays an important role in the diagnosis of cardiovascular diseases and it’s a fundamental tool for patient management. In my institution, I work with cardiac computed tomography (CT) and cardiac magnetic resonance (MR). Both are used in a wide spectrum of conditions that affect patients of all ages, from new-born babies to the elderly. The most common pathologies vary according to the age group; congenital heart diseases predominate in children, non-ischaemic cardiomyopathies are commonly seen in young adults and ischaemic heart disease tend to be seen in older adults.
However, ischaemic heart disease with obstructive coronary disease and myocardial infarction is more and more frequently observed in patients aged 30 to 40, due to an increase in cardiovascular risk factors in younger adults, which is somewhat alarming. The selection of which modality to use in the emergency department in inpatients or outpatients depends on the type of pathology and the clinical question the referring physician wants to answer.
ESR: Which modalities are usually used for what purpose?
HG: Multiple imaging modalities are available for assessment of cardiovascular diseases including those that use ionising radiation (chest x-ray, CT, invasive angiography), radioactive isotopes (nuclear medicine), ultrasound waves (echocardiography) and electromagnetic fields (MRI).
A chest x-ray is the most common radiation imaging modality; it is accessible, inexpensive and uses a very low radiation dose. In the context of cardiovascular disease, it provides valuable information regarding the size of the cardiac silhouette, calibre of pulmonary vessels, calcifications in the aortic arch, and pleural effusion or pulmonary oedema that may be due to cardiogenic origin. A chest x-ray may give clues regarding the causes of symptoms, such as shortness of breath, dyspnoea or chest pain. However, a normal chest radiograph does not exclude cardiovascular disease, but usually indicates the absence of a serious problem.
Transthoracic echocardiography is the initial imaging modality to assess the heart. The modality is widely available, it can be done next to the patient’s bed and it provides very valuable information, both structural and functional, since it makes assessing cardiac chambers size, left ventricular function, valvular function and the presence of pericardial effusion possible. It enables us to quickly assess acute conditions, such as pericardial tamponade or regional wall motion abnormalities in patients with acute myocardial infarction. Also, echocardiography is the initial modality in the evaluation of congenital cardiopathies and valvular disease.
Cardiac CT is useful in patients who come to the emergency department with chest pain with low/intermediate risk of acute coronary syndrome, in order to exclude obstructive coronary disease. CT is also useful when acute aortic syndrome or pulmonary thromboembolism is suspected, in evaluation for surgical or endovascular complications, screening of clot in patients with cerebral stroke with suspected cardioembolic origin or in patients with congenital heart disease who require urgent intervention.
CT is used selectively in patients with stable chest pain for evaluation of coronary arteries, follow-up of coronary interventions, structural evaluation in congenital heart diseases, dysfunction of mechanical valvular prostheses and as a study for planning interventional procedures such as pulmonary veins isolation/ablation in patients with some types of atrial fibrillation or placement of transcatheter aortic valve implantation / replacement (TAVI/TAVR) in patients with severe aortic stenosis that cannot be treated by surgery due to its high surgical risk.
CT is also used as a screening modality with Calcium Score, which is a low-dose study without contrast medium that allows us to obtain information on the degree of calcification in the coronary arteries, which helps to know the cardiovascular risk. Therefore CT also has a prognostic value in asymptomatic patients.
Cardiac MRI is a robust modality that can provide a large amount of useful information in multiple cardiac conditions. It is the gold standard for biventricular function, it provides accurate information on ejection fraction, end-diastolic volume and end-systolic volume, stroke volume and myocardial mass. MRI is especially useful in conditions where it is not possible to determine left ventricular function or where it is necessary to know the right ventricular function, for instance in postoperative patients with tetralogy of Fallot or pulmonary hypertension. MRI is the only modality that can help us to know these parameters. One of its advantages is myocardial tissue characterisation in ischaemic and non-ischaemic cardiomyopathies, allowing us to determine the presence of necrosis – as in myocardial infarction, where it helps in assessing viability –, fibrosis – as in some myocardiopathies – or infiltrative processes, such as amyloidosis.
Other sequences such as T1, T2 and T2* maps enable us to evaluate the myocardium in inflammatory processes, diffuse processes or by deposits. MRI also allows an accurate evaluation of cardiac and vascular anatomy, which is very useful in congenital heart diseases. Flow quantification allows haemodynamic evaluation in conditions such as systemic-pulmonary short circuits and valvular disease (insufficiency and stenosis). MRI is the ideal modality in the characterisation of cardiac masses. It also allows evaluation of acute or chronic pericardial pathology, such as constrictive pericarditis.
ESR: What is the role of the radiologist within the ‘heart team’? How would you describe the cooperation between radiologists, cardiologists, and other physicians?
HG: Communication between members involved in the care of patients with cardiovascular disease is fundamental for their adequate management. Before performing any non-invasive cardiac imaging study, it is fundamental for the radiologist to know the reason why the study is requested. The radiologist must also know a patient’s clinical history in detail to be able to establish the most appropriate protocol depending on the clinical question to be answered.
The role of the cardiovascular radiologist in the heart team is extremely important since all the information provided by imaging modalities such as CT or MRI help make management and treatment decisions. The radiologist facilitates the understanding of the pathology and, to achieve this, it is fundamental to demonstrate with images what is being described in the report.
It is necessary to create multiple reconstructions (MPR, MIP, VRT) in order to demonstrate key findings so that the rest of the team members understand more easily and can better plan medical, surgical or endovascular management.
ESR: Radiographers/radiological technologists are also part of the team. When and how do you interact with them?
HG: Radiological technologists and nurses in MRI or CT rooms are key and extremely important elements in the workflow for cardiac imaging. My interaction with them is constant and takes place directly in the imaging rooms. Communication is essential to obtain excellent quality studies. It is common for me to be asked to review the images before sending the patient home, in order to determine if it is necessary or not to perform additional sequences.
However, there are two conditions in which the interaction is closer, where the radiologist and radiological technician perform the exam together: MRI of congenital heart diseases and cardiac masses. In both conditions, the protocols and series may vary according to the findings during the exam, and adding additional series that were not previously planned in the protocol is quite common.
Feedback and suggestions to the members involved in study acquisition are very important when required, in order to progressively improve study quality and avoid future mistakes.
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?
HG: In the morning I work in a public hospital, where I dedicate all my time to reviewing cardiac imaging studies (MRI and CT). I am the only radiologist doing this task, but I have great support from radiology residents, who do a great job every day. I also dedicate academic time giving lectures to radiology, cardiology and paediatric cardiology residents.
In the afternoon I work in a private practice, where 50% of my time is dedicated to cardiac imaging and 50% to reviewing non-cardiac MRI studies. I particularly review studies of brain, spine, abdomen, knee and shoulder. I use part of my free time to prepare conferences, educational exhibits and writing publications.
ESR: Do you have direct contact with patients and if yes, what is the nature of that contact?
HG: Yes, I have direct contact with patients, most of the time. Whenever possible, I like to talk personally with patients, to know them and their concerns before the study. I like to explain to them the reason for the study and what information we will obtain from it. It is very important to explain how the exam (MRI or CT) will be performed, to know its duration, noises that patients will hear and what they will feel when the contrast medium is administered.
I always explain to them what they have to do during the exam and I practise with them breathing exercises to maintain apnoea. An informed consent is signed after the procedure is explained in detail by part of the team, usually the nurse or the technologist.
After the exam, we always check patients to rule out any complications or allergic reactions.
ESR: If you had the means: what would you change in education, training and daily practice in cardiac imaging?
HG: Currently, global communications are facilitated by the internet, so I would focus my efforts in greater inter-institutional cooperation through remote meetings for case conferences, review of protocols, experience sharing, journal club and educational conferences among members of different institutions around the world, in order to share and update the knowledge of cardiovascular imaging. I would increase the use of resources provided by technology to transmit ideas through videos, animations and illustrations, in order to facilitate the learning of radiologists in training.
The implementation of technologies such as virtual reality or 3D printing should be incorporated in the education and daily clinical practice for planning interventional or surgical procedures. I would hope for a greater dissemination of cardiac imaging information among groups of referring physicians, so that they know the potential and limitations of each modality, in order to obtain the desired information in each particular case.
ESR: What are the most recent advances in cardiac imaging and what significance do they have for improving healthcare?
HG: CT and MRI, the two modalities I work with every day, have shown tremendous advances in recent years that have become particularly useful in cardiac imaging.
CT with dual-source technology has enabled to significantly increase temporal resolution, which allows us to obtain images of the heart without motion, even with heart rates of around 80 bpm, a result that was only possible with heart rates of up to 60 bpm some years ago. Faster scanners have also been developed thanks to the increase in the number of detectors, which is currently up to 320 detectors, allowing 16cm coverage in the z-plane (cranio-caudal) in a single gantry rotation.
Spectral CT has greatly advanced with dual-layer spectral detector CT, which allows us to obtain spectral information – multi-energy spectral CT – in all the studies performed with this technique. We have invested a lot of effort and resources in dose reduction strategies in recent years, and we currently perform studies with a very low radiation dose, while maintaining high diagnostic quality thanks to iterative reconstruction.
MRI has also improved in all aspects, allowing even faster studies without sacrificing image quality, such as the use of compressed sensing imaging, which allows fast cardiac studies even with free breathing, and the appearance of very useful sequences such as T1, T2 and T2* maps or dynamic MRI angiography. Hardware improvements allow much more efficient scanners in all aspects.
Great advances have also been seen in the post-processing tools, facilitating and shortening working time, thanks to processes and algorithms that allow an automatic or semi-automatic analysis in most cardiovascular studies.
All improvements allow us to obtain images with better quality, which directly influences the diagnosis of each patient.
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?
HG: In addition to the great technological advances in all imaging modalities, there has been a favourable trend to using multimodality imaging in the evaluation of cardiovascular pathologies, putting together valuable information provided by each modality – echocardiogram, nuclear medicine, computed tomography and magnetic resonance. This allows us a better understanding of the pathologies and to better establish a therapeutic plan.
The use of hybrid modalities such as PET/CT and PET/MR is now more common, allowing us to obtain anatomical, functional and metabolic information all at the same time. Something that has particularly surprised me in the last two or three years has been the appearance of a new technique of 3D reconstruction, called cinematic rendering, which produces extremely realistic images that I personally love to work with.
The future is very promising for cardiac imaging. CT has had great advances and I think it will continue to do so, improving its temporal and spatial resolution, decreasing radiation dose and improving iterative reconstruction. With the use of spectral CT and CT myocardial perfusion in conjunction with the evaluation of coronary arteries and ventricular function, we can get a complete study with low radiation dose and a lower amount of contrast medium. I think that spectral CT has a long way to go, and we have seen great advances in this field recently.
MRI will continue to improve its acquisition times, which will be increasingly shorter without sacrificing image quality. Wider bore and shorter tunnels help reduce claustrophobia issues. Additionally, multiple new sequences are a work in progress; these will be very useful for cardiac imaging in the future.
ESR: Is artificial intelligence already having an impact on cardiac imaging and how do you see that developing in the future?
HG: There is no doubt that artificial intelligence has an important role to play in cardiac imaging – from the technology of synchronisation with electrocardiogram, where the scanner is able to detect arrhythmias and automatically adjust parameters depending on the patient’s heart rate, their weight, the respiratory pattern, to post-processing tools where with just a few clicks many complex processes such as extraction of the coronary tree or the calculation of ventricular function are run automatically.
Artificial intelligence will continue to be a fundamental tool in cardiac imaging, helping to characterise atheromatous plaques, determining the degree of vascular stenosis and showing incidental findings such as pulmonary nodules. Without a doubt, it is a great help for the eyes of expert radiologists.
Dr. Harold Goerne is a cardiovascular radiologist and professor of cardiac imaging in the Western National Medical Centre of the Mexican Social Security Institute and Imaging and Diagnosis Centre in Guadalajara, Jalisco, México. He completed his radiology residency in 2011, and since then has shown special interest in cardiac imaging. In 2012 he trained in cardiac imaging at the Cardiology National Institute Ignacio Chávez in Mexico City. In February 2017, he completed a one-year visiting senior fellowship in cardiac imaging in the division of cardiothoracic imaging of the department of radiology at University of Texas Southwestern Medical Center, Dallas, US. His work and publications are focused on cardiac CT and MRI, and he has a special interest in academics, working directly with radiology and cardiology residents. He has presented 33 cardiovascular imaging lectures in national and international meetings, and has received five educational exhibit awards from the RSNA and ARRS. He has participated as the first author and co-author in multiple publications and book chapters related to cardiac imaging.