PhD Defence Rianne van Rijswijk | Towards optimized abdominal aortic aneurysm care - Prediction of sac regression & 3D ultrasound

Towards optimized abdominal aortic aneurysm care - Prediction of sac regression & 3D ultrasound

Rianne van Rijswijk is a PhD student in the Department of Multi-Modality Medical Imaging. (Co)Promotors are prof.dr. M.M.P.J. Reijnen and dr. E. Groot Jebbink from the Faculty of Science & Technology and dr. J.M. Wolterink from the Faculty of Electrical Engineering, Mathematics and Computer Science.

This thesis has contributed to the optimization of abdominal aortic aneurysm (further ‘aneurysm’) care by obtaining evidence on predictors of sac regression and demonstrating the feasibility and accuracy of a commercially available 3D ultrasound system before and after endograft placement.

Sac regression is an important process that is linked to superior treatment outcomes, but it is still unknown which factors are related to it. In this thesis, increasing evidence was found that preoperative anatomical features of the aneurysm, mostly thrombus-related, are associated to sac regression. The performances of the sac regression prediction models improved over the course of this thesis, but not to the extent that allowed for implementation in clinical practice. Although identification of strong evident predictors of sac regression was complicated, this thesis resulted in many leads for future research; most importantly the theory that sac regression is a multifactorial and complex process.

Aneurysm imaging is indispensable for detection and prediction of sac regression, and for general aneurysm diagnosis, treatment and follow-up. 3D ultrasound is emerging as a promising technique for aneurysm imaging, as it is a non-invasive low-cost imaging modality that produces a 3D overview of the aneurysm and the endograft, overcoming most of the disadvantages of conventional duplex ultrasound and CT imaging. This thesis demonstrated feasibility of a commercially available 3D ultrasound system for aneurysm imaging before and after treatment, with good correspondence to CTA. Even though not all follow-up parameters could be evaluated on 3D ultrasound, the machine definitely demonstrated potential for aneurysm imaging in clinical practice. It is hypothesized that 3D ultrasound would offer a useful addition to conventional duplex ultrasound.

Overall, both sac regression prediction & 3D ultrasound proved their potential for optimization of aneurysm care. Identification of predictors of sac regression can contribute to personalization of aneurysm treatment and follow-up and might result in an overall higher survival rate after treatment. Moreover, implementation of 3D ultrasound would allow for harmless bedside 3D imaging and enable retrospective aneurysm assessment while decreasing CT-imaging-related cancer.