As we continue to fight the COVID-19 pandemic, health professionals all over the world are not only still dealing with cases of acute COVID-19, but also patients with long term problems associated with the virus. COVID-19 infection can damage the lungs, heart and brain. High-quality imaging in all modalities is essential for diagnosis, monitoring, treatment and follow-up of both COVID-19 and post-COVID-19 patients. The state-of-the art features of Canon Medical’s range of imaging solutions are proving invaluable in research and management of COVID-related changes. Some of the world’s leading physicians shared their latest findings on imaging and treatment outcomes for these patients in a Canon Medical webinar that was Chaired by Professor Joao Lima from the Johns Hopkins University, Baltimore, US.

The effects of COVID-19 on the lungs became immediately obvious in the pandemic. Now, there is considerable focus on what happens to the lungs as people convalesce and survive COVID-19. Chest CT emerged right at the beginning as the modality of choice for COVID-19. It has already proved very useful in acute conditions for positive and differential diagnosis, for risk stratification, and for follow-up of acute complications, including Pulmonary Embolism (PE), superinfection, acute respiratory distress syndrome (ARDS). CT is now under consideration for longer term follow-up of fibrosis.

It is considered usual to find persistent abnormalities at three-months after initial infection. Professor Mickaël Ohana, Consultant Radiologist at Strasbourg University Hospital, Strasbourg, France, explained findings from one of Europe’s most intense COVID-19 clusters.

“Our institution was essentially a ‘COVID-19 hospital’ for at least three months. Together with our pulmonologists, we prospectively monitored patients that were hospitalized for the disease with comprehensive respiratory follow-up at three- and six-months that included a Chest CT,” he explained. “More than two thirds of patients had abnormal Chest CT at three-months, but only 50% had persistent abnormalities at six-months. The persistent abnormalities at six-months were seen only in patients who initially had critical disease, and they were rated as minor.

The lesions were mostly peripheral: parenchymal bands, bronchiectasis, honeycombing - and are mostly limited in their lung parenchyma extension. They rarely seem to extend over 10% of the total lung parenchyma. No oxygen therapy was required among the patients after their initial COVID-19 episode. Symptoms in these patients are usually quite rare.”

“It looks like there could be a disconnection between the physiology and clinical evolution, which looks relatively and surprisingly good,” he added. “Follow-up Chest CT should not be carried out before six-months after discharge, otherwise, it’s too early, and you will find lesions that you will not know what to do with.”

It is essential that radiation dose is adequately optimized in these patients with the lowest dose possible. This is possible due to Canon Medical’s Deep Learning Reconstruction technology, Advanced inteligent Clear-IQ Engine (AiCE) ensuring the highest IQ with lowest dose. AiCE is powered by Altivity; AI innovation that uses smart technologies to make a whole new level of quality, insight and value across the entire care pathway possible.

“In 2020, we carried out around 1,000 examinations with an iterative reconstruction technique. We also performed about 1,000 examinations with the exact same acquisition parameters, but with AiCE, and we managed to achieve a 24% reduction in radiation dose, without doing anything more. This technology is very, very efficient,” remarked Professor Ohana.

Although pulmonary findings are the most well-known presentation, COVID-19 infection affects multiple organ systems. Therefore, beyond Chest CT, comprehensive imaging exam of convalesced patients on MRI without ionizing radiation may be helpful for the risk stratification and adequate follow-up of patients with Post-COVID conditions.

The Johns Hopkins School of Medicine, Johns Hopkins University in Baltimore, US, has developed a comprehensive COVID-19 MRI protocol, which includes brain, lung, heart and liver. It uses a one-hour scanning protocol, which consists of non-contrast and post-contrast imaging.

“We aim to characterize the cardiopulmonary consequences in individuals who required hospitalization for COVID-19, using state-of-the-art CT and MRI from Canon Medical,” said Dr. Yoko Kato, Post-doctoral Fellow Cardiovascular Imaging. “We first scan the brain, and then move on to the liver and heart (non-contrast images) and after that, we acquire the lung perfusion images following administration of Gadolinium contrast. And after use of the remaining dose of the contrast, we acquire the post-contrast lung UTE, as well as cardiac MRI images. We acquire diffusion images (DTI) and flow-sensitive black blood (FSBB) images for the best vasculature assessment. MP RAGE (Magnetization Prepared - RApid Gradient Echo) for the brain volume and structural assessment and T1, T2 and T1-wall mapping for the tissue characterization.”

“Post-COVID patients don’t necessarily show symptoms, but pulmonary and cardiac abnormalities were observed in our study,” she added. “Comprehensive multi-organ imaging may benefit convalesced patients by detecting sub-clinical findings, which may need careful follow-up.”

The potential diversity of post-COVID complications is becoming apparent. The disease can provoke many conditions, such as myocardial dysfunction. Features of Canon Medical’s ultrasound that can help differentiate the underlying evolution of complications are proving invaluable.

“During the pandemic, we have learned that our Canon Medical’s ultrasound system is very useful for two things: to ‘rule out’, and ‘for early detection’,” remarked Professor Leopoldo Pérez de Isla, Head of Cardiovascular Imaging Unit at Clinico San Carlos, Complutense University of Madrid, Madrid, Spain. “We can rule out the presence of cardiac failure, coronary endothelial dysfunction, pericardial involvement, dysautonomia or inappropriate tachycardia and the causes of chest pain. We can also detect several problems earlier such as myocardial dysfunction, pulmonary embolism and infective endocarditis.”

“We know that COVID-19 is able to provoke several cardiac and pulmonary conditions by itself, but it is also able to decompensate a previous chronic heart failure. It is very useful to differentiate between heart failure and other problems because it has very important clinical implications, and we do it by means of echocardiography,’ he added.

“My echocardiography system is also able to provide me with information that is crucial for the management of my patient,” continued Professor Pérez. “It is able not only to show me the patients’ left ventricle, for example, but also provides me with more information because we can use some technology, such as the auto ejection fraction, which means we can obtain the left ventricular ejection fraction (LVEF) in a very easy and a very fast way. With echo cardiography, we can study the contractility. We have even more accurate systems, such as wall-motion tracking.” The Canon Medical system provides 2D Wall Motion Tracking and 3D Wall Motion Tracking.

“With this, we can analyze all four cardiac chambers for a complete analysis of the heart. The system is very accurate and can detect very early myocardial damage, for example,” he said. “While experts might not immediately feel they need such a system, we have residents, fellows, and even non-cardiologists carrying out echocardiograms, and they are happy with an automatic system that is very easy to use and provides them with information from very accurate technology, regarding the contractility of the heart.”

COVID-19 patients that have been admitted to hospital for a long period can suffer infections, and endocarditis must be ruled out.

“In these cases, my system is also able to help me, because we can use the transesophageal probe in order to detect the presence of vegetations in the valves,” remarked Professor Pérez. “We can use, not only the 2D image, but a color Doppler image and the 3D images. The accuracy of these images is really nice. We can use it in order to detect vegetations. Combining the 2D and 3D transesophageal images we can also analyze and obtain a lot of different measurements based on the tracking of the valves.”

The ultrasound system is able to detect different thromboses at different locations.

“My ultrasound system is able to rule out diseases that are frequently seen in patients with COVID-19 as well as provide early detection of disease not seen with other imaging techniques. Early detection and rule out of disease is crucial for both diagnosis and management of patients with COVID-19,” he concluded.

The Bichat-Claude Bernhard Hospital, University of Paris, Paris, France, installed two Cath labs equipped with Canon Medical’s Alphenix Core + systems. Professor Laurent Feldman, Professor of Cardiology and Director of the Catheterization Laboratory at the hospital has been particularly impressed with the dose reduction features of the new systems.

“We are using several of the tools routinely to reduce irradiation. The dose tracking system (DTS) is a very intuitive system, which provides the clinician with information on the skin dose delivered to the patient during the procedure.

Live zoom provides you a magnification of your views, but without increasing the dose. With Live Zoom, we have been able to reduce dose by 35 to 48%. It is a very interesting tool that provides a big image, good definition, at low dose.”

SPOT ROI is another feature which is a very unique to the Canon Medical Alphenix Core + rooms that provides excellent definition of an area of interest, but with an attenuation of what is around this. This allows dose reduction of more than 60%.

“We are using this feature especially in a very complex PCI and CTO procedures, when we know that we’re going to spend a lot of time, and that dose reduction is particularly important,” he commented.

Stent Enhancer is another feature that Professor Feldman and his team use a lot.

“It doesn’t reduce dose necessarily but gives a very fine definition of the way a stent has been deployed. And by doing so, you don’t have to do extra angiograms, and so altogether, you reduce the dose. The One-Shot function is only one frame, but if you do this properly you can have a very fine definition of the stent, you can see there is some underdeployment of the stent, and this clearly reduces the dose,” he explained.

Another way to reduce the dose is to use less X-Ray and to carry out multi-modality imaging.

“We have integrated different imaging and physiology systems in our Alphenix Core + rooms,” said Professor Feldman. “As they are integrated, they are very easy to use. Usually with one switch. So, more imaging, more physiology and less X-ray. That’s a fine way to reduce dose.”

While the challenges of the COVID-19 pandemic continue, research using Canon Medical’s advanced technology is contributing to fighting the world’s current health crisis. //

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