Pieter Boone
Phd Student
Time-resolved CTA

PhD student Contrast enhanced Computed Tomography Angiography (CTA) has emerged as an important non-invasive imaging modality for imaging the human vascular structures, more particular imaging of neuro, cardiac, body and lower extremities. In the last few years, the advent of wide beam CT scanners (up to 16cm volume) allow to perform multiple CT acquisitions over the same structure at a high frame rate, enabling to obtain time-resolved CTA data. Potential benefits of such dynamic series can be identified as both morphological as quantitative & functional. Today, no such dynamic information is available in CT imaging. Clinically, contrast flow can be assessed by digital subtraction angiography (DSA), but this is a 2D technique and it does not offer 3D information as with CTA.

The main objective of this project is to combine 3D images with hemodynamic information by adding a dynamic (temporal) aspect to CTA imaging. This novel technique can lead to an improved morphological, quantitative and functional assessment of vascular structures which could improve diagnosis by enabling patient-specific treatment. Initially, this project will focus on patients with suspicion of lower limb Peripheral Arterial Disease (PAD) by applying the technique to the calves and feet. In an additional stage, the technique will be expanded to other vascular structures such as the kidneys.

Lower limb PAD is a chronic atherosclerotic process that causes partial or complete narrowing of the arteries. These obstructions will cause a decreased blood flow which can lead to tissue death if the patient is not treated properly. In Belgium, 7% of the male and female population, respectively above 45 and 55 years old, has lower limb PAD without showing symptoms. In addition, 7% will suffer from pain in their legs while walking. Time-resolved CTA could play an important role in the diagnosis and treatment of PAD as it could offer an improved visualisation of the vascular structures combined with functional information regarding the blood flow and muscle perfusion.

To explore the added value of time-resolved CTA, smaller objectives are created. The first objective will be to design a balanced CTA and perfusion protocol in terms of radiation dose, scan quality and temporal resolution. This balance will be critical for the patients’ health as for the accuracy of the results. The second objective consists of creating an image processing pipeline for the automatic quantification of dynamic parameters such as blood velocity and arrival time of the contrast bolus. For the third objective, the previously created pipeline will be adapted to quantify the circulation of blood in the muscles (perfusion) and to examine the direct effect of occlusions on the surrounding muscles. The fourth objective is to validate and evaluate the created technique, both experimentally as clinically. A phantom study and a clinical study, before- and after revascularisation, have to prove the reproducibility and added value of the technique. The final objective is to create a software tool for the combined assessment of blood flow and tissue perfusion.