Advanced CT Exams for Heart and Vessels

Photo of part of the research group in front of the new photon counting detector comuputed tomography

Cardiovascular disease (CVD) in general and coronary artery disease (CAD) in particular are the most common causes of death in the world. CVD is also the most expensive disease group, accounting for approximately 9% of the total health care expenditure in the European Union.

Computed tomography (CT) is an increasingly used modality for investigations of patients with suspected CAD. A number of modalities for imaging of the coronary arteries are currently used among them coronary computed tomography angiography (CCTA), first described in 1995. Since then, CT technology has taken quantum leaps.

The Flagship Project

This flagship project combines mainly coronary artery morphology and cardiac function research with CT at CMIV.

The research is carried out in close collaboration between the coronary artery group, led by CMIV director and professor Anders Persson, together with Mårten Sandstedt PhD and senior physician, Magnus Janzon head at the department of cardiology, Associate Professor and the cardiac imaging and modelling group with Tino Ebbers, professor in Physiological Measurements and Matts Karlsson, professor and director of National Supercomputer Center. With translational research approach, we expect to improve the in-depth understanding and diagnostics of cardiovascular disease and treatment strategies.

The European Society of Cardiology published new guidelines in 2019 suggesting that "Coronary Computed Tomography Angiography (CTA) is the preferred test in patients with a lower range of clinical likelihood of CAD, no previous diagnosis of CAD, and characteristics associated with a high likelihood of good image quality."
As the first university hospital in Sweden CCTA were introduced at CMIV in 2004 into clinical routine for patients with suspected CAD.

As part of Mårten’s thesis, an AI software for automatic calcium scoring was evaluated. A calcium scoring is performed by scanning the heart without intravenous contrast, and is used for a coronary artery calcification quantification, which is employed for a clinical cardiovascular risk analysis. The quantification process is traditionally performed using semi-automatic post-processing softwares and is not very difficult, yet it takes significant expert time and is considered tedious. This CMIV project found a very good agreement between the semi-automatic and AI-based automatic methods, but AI was shown to have time-saving potential, which is valuable both for the work environment and for health economy.

Another work in Mårten’s thesis has been performed together with the Mayo Clinic, Mn, USA. In this project, coronary specimens from human cadavers were examined with a conventional CT and a photon counting detector CT (PCD-CT). Subsequently, a coronary calcification quantification was performed, demonstrating the PCD-CT technology to be more accurate than the conventional CT.

With constantly decreasing radiation doses, it has become possible to acquire 3D images of a complete heartbeat. This so called 4D information can be used for functional assessment of the heart by using advanced post-processing, machine learning and simulations. Functional information, as for example blood flow in the whole heart, can be obtained which can give valuable information in the prediction of the risk for formation of blood clots, which can cause a heart attack or stroke. It can also be used to compare the effect of different surgical treatment options, like the choice prosthetic heart valve, as shown by Jonas Lantz.

Photo of part of the research group in front of the new photon counting detector computed tomography

Magnus Janzon, Mårten Sandstedt and Anders Persson in front of the new photon counting detector computed tomography.

Future aspects

The new research PCD-CT that CMIV installed in July offers new opportunities in imaging of the coronary arteries and assessment of cardiac function. This technology is currently limited to very few centers in the world and conveys excellent possibilities for further cardiac CT developments. The scanner has several benefits compared to clinically available CT scanners, such as higher resolution and lower radiation dose. In cardiac imaging, the improved spatial resolution facilitates the assessment of coronary artery calcifications more accurately and new types of functional imaging possible. The PCD-CT scanner’s high-resolution abilities may evaluate coronary artery calcifications more accurately, and unnecessary invasive examinations can thereby be minimized. It gives us unimagined opportunities for the future and great advantages in cardiac diagnostics.