Prof. Johan de Mey, M.Sc. Pieter T. Boonen, Prof. Nico Buls, Prof. Dimitri Aerden

The Alphenix 4D CT has been revolutionizing research in Interventional Radiology at the Department of Radiology, UZ Brussels University Hospital (Brussels, Belgium). Prof. Johan de Mey, the Head of Department, has selected Canon's Alphenix 4D CT to bridge the powerful image quality of CT with the versatility and flexibility of angiography. Together with his team, M.Sc. Pieter T. Boonen, Prof. Nico Buls, Prof. Dimitri Aerden, and Prof. Jef Vandemeulebroucke, he showed the benefit of using the Alphenix 4D CT to improve the evaluation of critical limb ischemia, providing valuable information on the anatomy of the blood vessels, the hemodynamic of the blood flow, and the tissue perfusion. In the future, Prof. de Mey and his department are eager to look forward and take advantage of all the clinical capabilities that this clinical system offers.

Meeting UZ Brussels
UZ Brussels is a university hospital that is part of the Vrije Universiteit Brussel (VUB) located in Belgium. This hospital offers a broad high-quality medical service, investing in innovative and cutting-edge medical equipment, and developing novel research. In 2020, the Alphenix 4D CT from Canon was installed in the Department of Radiology.

The department encompasses both diagnosis and intervention, being also involved in several research projects on medical applications. On a daily basis, Alphenix 4D CT is used for biopsies to collect clinical information regarding suspicious tissue in the body. However, more can be done in interventional radiology, for instance, with a system that integrates two powerful and robust medical modalities, CT and angiography, in only one room. Following a patient-centric approach, the patient does not need to be transferred between two rooms anymore to be diagnosed, treated, or verified after treatment. This possibility of easily switching between CT and angiography in one setting without moving the patient, improves patient care, decreases procedure time, and makes the procedure less logistically challenged. Therefore envisioning the improvement of clinical workflow and integration of cutting-edge methods and technology, Alphenix 4D CT brought to the department the urge to search for new and innovative methodologies for cardiology and interventional oncology.

Breakthroughs in the diabetic foot field
The most recent work from Pieter T. Boonen, Prof. Nico Buls, Prof. Dimitri Aerden, Prof. Jef Vandemeulebroucke, Prof. Johan de Mey, and their team was published in Radiology and European Radiology Experimental^1,2. Radiology and European Radiology Experimental are two highly esteemed academic journals in the field of radiology and medical imaging. In these papers, they presented a methodology to assess the hemodynamic effect of critical limb ischemia in the foot using Alphenix 4D CT functionalities and perfusion imaging. In the first publication, the researchers applied this methodology to one patient with diabetic foot disease and already showed the benefits of using it to evaluate and plan the treatment of this disease. In the second publication, they extended the work to two more patients. This methodology, requiring a minimal contrast of only 2 mL, enables the acquisition of valuable information on blood vessel anatomy, hemodynamics, and tissue perfusion. The obtained hemodynamic parameters correlated well with intra-arterial digital subtraction angiography (IADSA) findings, surpassing it in assessing venous blood flow and inflammatory hyperperfusion.

This study integrates into the peripheral arterial disease (PAD) field. PAD manifests as a circulatory problem that results in the narrowing or blockage of the peripheral arteries, reducing the blood flow to the extremities. Typically, it results in patients developing critical limb ischemia, which leads to severe consequences for patients with diabetes (e.g., diabetic food disease). This disease is usually assessed with IADSA, which provides morphological and hemodynamic information about the lesion, but it does not provide information on tissue perfusion. In addition to this, IADSA only delivers 2D information on the structures. Therefore, an image modality that allows for volume projections, like dynamic four-dimensional computed tomography (dynamic 4D CT) may be an alternative to get more details about the structures in the image. However, recent studies reported the use of high levels of the contrast agent when acquiring dynamic 4D CT images.

In this work, the researchers included data from three patients with diabetic foot disease and a high suspicion of critical limb ischemia. Between January 2021 and August 2021, these patients underwent a dynamic 4D CT examination in combination with a diagnostic IADSA in the Alphenix 4D CT room at the UZ Brussel diabetic foot clinic.

With the approach of acquiring the dynamic 4D CT images using the Alphenix 4D CT, the amount of contrast agent used was very low (2 mL) as a result of the selective intra-arterial injection for the CT acquisition. Other studies reported the intravenous injections of 40 to 80 mL of contrast agent when the patient undergoes a dynamic 4D CT examination. The use of only 2 mL of contrast agent in these procedures has a clinical benefit, especially for patients with diabetes and chronic kidney disease, since the use of a high amount of contrast increases the risk of contrast-induced nephropathy in these patients.

In addition, a more detailed and informative assessment of blood flow and tissue perfusion was achieved with dynamic 4D CT images than with stand-alone IADSA. On the morphological and hemodynamical levels, dynamic 4D CT and IADSA correlated. However, as previously mentioned, dynamic 4D CT also allows obtaining perfusion maps, in which, as expected, the values of the affected tissues were significantly higher than those of the normal tissue, which is suggestive of inflammatory hyperperfusion.

In closing, this exploratory study showed that the methodology introduced by the researchers has the potential to provide anatomical and hemodynamic information on vascular structures, and insights on tissue perfusion with a minimal amount of contrast. The technique has the potential to contribute to a better diagnosis of critical limb ischemia in the future.

Stepping into the future in UZ Brussels
After the successful outcomes already achieved by the team, they are now planning to move forward and incorporate the cutting-edge multimodal capabilities of our Alphenix 4D CT into new research and clinical applications. Cardiology, interventional oncology, and interventional radiology are three clinical pillars for which they see the benefit of using Alphenix 4D CT not only for advanced diagnosis but also for advanced treatment. In cardiovascular applications, dynamic 4D CT imaging offers a dynamic visualization of the heart and blood vessels, providing crucial insights into cardiac function and blood flow.

This technology could enhance diagnostic precision in identifying coronary artery diseases, aneurysms, and other cardiovascular conditions, leading to more informed treatment decisions. In interventional oncology, the implementation of dynamic 4D CT imaging allows for real-time imaging during minimally invasive procedures. By capturing dynamic changes in tumor vascularity and surrounding structures, clinicians could navigate interventions with increased accuracy, potentially improving the efficacy of treatments such as embolization and ablation.

Finally, in interventional radiology, Canon’s Alphenix 4D CT can be a perfect solution for Endovascular Aneurysm Repair (EVAR) procedures and its most common related complication called endoleaks. EVAR is a minimally invasive technique that is commonly conducted to repair abdominal aortic aneurysms (AAAs) using a stent-graft. This treatment has emerged as an alternative to open aneurysm repair procedures. However, EVAR can be affected by endoleaks, which are blood leaks outside the stent-graft and back into the aneurysm sac. There are different types of endoleaks, depending on the vessels that cause the inflow into the aneurysm sac. With Alphenix 4D CT, it will be possible to assess and treat this clinical complication within one room and by avoiding extra logistic actions. Moreover, using dynamic 4D CT imaging would be highly beneficial to determine the information about the hemodynamics of the blood flow to improve the endoleaks diagnosis and treatment. Next to these clear advantages, image fusion between CT image data and angiography is fast and straightforward since the patient is positioned on the same table, which means that no registration between the two imaging modalities is necessary. This three-dimensional image fusion guidance can improve the procedure time and reduce the amount of used contrast. Another strong advantage of this image fusion is the additional confidence given to the vascular surgeon and/or interventional radiologist during the procedure to improve patient outcome.

The Alphenix 4D CT is therefore shaping up to be a gamechanger in the Department of Radiology, at UZ Brussels. With their interest in integrating the Alphenix 4D CT into their clinical routine, we can foresee that the road ahead is bright, bringing improved diagnostics and better treatment for all.