Doctoral dissertation

Digital Image correlation as a novel method to study and analyze the deformation of the heart

The performance of the heart is closely tied to its deformation during blood circulation. Various versions of echocardiography techniques have long been used in the medical field to monitor and study the deformation of the heart. However, each come with their own set of limitations and challenges. Digital Image Correlation, as a novel method of deformation analysis has the potential to provide a deeper understanding of the inner workings of the heart.

As the name implies, during the open-heart surgery the heart is both physically and visually accessible. This makes it possible to acquire images during the operation. As this type of surgery is among the most complicated and challenging surgeries, any additional information gained from how the heart is functioning from one moment to the next can be the difference between life and death.

While many different echocardiography methods have proved useful to monitor the functioning of the heart, they all have shared and individual limitations. They comprise the need for highly trained operator, physical contact with the patient, difficulty in fully describing the deformation of the heart, among other things.

This research takes the initial steps is using DIC to study the deformation of the heart. Many of the challenges faced during the experiment arose from the extremely controlled environment of the surgery room. Setting up of the cameras while not interfering with the sterile area around the heart, applying suitable contrast pattern on the heart, controlling the lighting etc. were all challenges that needed to be overcome. In spite of these challenges, good results were acquired from a number of surgeries.

In the next step, first the usability of the data provided by DIC was assessed. This was then followed by demonstrating the ability of DIC to provide additional types of data not easily acquired from echocardiography. Furthermore, DIC can easily provide crucial information on the anisotropy of the heart deformation.

The DIC analysis can also provide deformation heatmap images of the ROI. While useful to get a sense of the overall deformation, these images are not visually quantifiable, although the contain information of the completely visible surface of the heart. A novel of method of quantifying these images into simple vectors was used with good results, showing that there is even more room to explore when it comes to using DIC in studying the deformation of heart.

MSc Ayat Soltani will publicly defend his doctoral thesis In-Vivo Digital Image Correlation Studies of the Motion and Deformation of the Human Heart during Open Heart Surgery on Friday 26th June 2020 at 12:00 at Tampere University in Festia, Pieni Sali 1, Korkeakoulunkatu 8. Professor Vadim Silberschmidt (Loughborough University, United Kingdom) and Associate Professor Sven Bossuyt (Aalto University, Finland) will act as the opponents. Associate professor Mikko Hokka from the Laboratory of Materials Science will act as Chairman.

The dissertation is available online at: