Time-resolved CT angiography for combined assessment of blood flow and tissue perfusion 

Lower extremity peripheral arterial disease (PAD) is a common cardiovascular disorder in elderly patients that causes a reduced blood flow towards the lower extremities, due to partial or complete narrowing of the arteries. Reported worldwide prevalence is in the range of 3% to 10%, increasing to 15% to 20% in people over 70 years. These values are expected to rise as the population grows older, smoking persists and the occurrence of obesity and diabetes mellitus increases. Especially diabetic patients are at risk since they have a 4-fold increased risk of developing PAD and the estimation is that in 2025, a total of over 65 million people in Europe will suffer from diabetes mellitus. For these patients, complications of foot ulcers are the leading cause of hospitalisation and amputation, resulting in an expenditure of 20-40% of the healthcare resources spent on diabetes. These numbers demonstrate the need for a detailed diagnosis of lower extremity PAD and an improved examination of foot ulcers to enable patient specific treatment.

In order to accurately assess the location and severity of arterial lesions, various imaging modalities are used. Both contrast-enhanced magnetic resonance angiography (CE-MRA) and computed tomography angiography (CTA) are progressively replacing conventional digital subtraction angiography (DSA) in many hospitals. In particular, run-off CTA is becoming the preferred modality, providing high sensitivity and specificity compared to DSA. However, examinations of below-the-knee arteries remain extremely challenging for various reasons: suboptimal resolution caused by a reduced contrast concentration, decreased blood flow due to above-the-knee lesions and small vessel diameters.

"This project aims at developing a medical tool which enables patient-specific diagnosis,
pre-operative planning and monitoring of treatment for patients suffering from peripheral arterial disease. "

In recent years, there has been an increasing interest in time-resolved, contrast enhanced CT (CE CT) imaging. The advent of wide beam CT scanners (up to 160 mm z-axis coverage) allows to perform multiple CT acquisitions over a vascular structure at high temporal resolution. These time-resolved acquisitions enable to track a contrast bolus through arteries and could, as such, provide quantitative hemodynamic information on the blood flow. A reduced forward blood flow is highly indicative of PAD, and time-resolved CTA could add diagnostic confidence to the assessment of severe occlusive diseases in below-the-knee arteries. With regard to diabetic foot ulcers, this information is inadequate to predict healing of diabetic foot lesions. Assessment of microvascular foot perfusion using time-resolved CTA, could play an important role in avoiding or delaying future amputations.

This project aims at creating an improved diagnosis for patients suffering from PAD in order to enable patient-specific treatment and to prevent further development of critical limb ischemia by acquiring dynamic CTA images for both a morphological assessment as a hemodynamic assessment. Subsequently, we focus on diabetic foot ulcers by assessing the perfusion in the microvasculature for the diagnosis and treatment monitoring in order to avoid or minimize amputations. This could also be beneficial in the future treatment of critical limb ischemia, but our primary objective remains preventing critical limb ischemia on the long run. Technically this project aims at developing a medical tool which enables patient-specific diagnosis, pre-operative planning and monitoring of treatment.

This interdisciplinary project between engineering and medical technologies fits well within the broader strategy of ETRO and UZ Brussel to transform fundamental research and state-of-the-art techniques to applied research projects and clinical studies. In addition, the objectives of this project are in line with the strategic vision of De Vlaamse raad voor Wetenschap en Innovatie (VRWI) as it aims for an improved quality of live through innovation and co-operation. 

Achievements (Honors & Awards) 
  • Pieter Boonen is funded by the Research Foundation Flanders (FWO), file nr. 1S63719N
  • 2017: ie-net 1st place in the category Engineering Technology