Finite Element Model of Mechanical Imaging of the Breast for OpenVCT Software Platform

Styvhetsförändringar i bröstvävnad är ofta kopplade till en patologisk förändring. Vissa cancertyper som infiltererande duktalt carcinom kan vara åtta gånger så styv som fettvävnaden runt omkring. Genom att komprimera bröstet och mäta trycket på bröstets yta har man identifierat att det blir en lokal förhöjning i tryck där det finns en tumör. Med hjälp av den här typen av mekanisk avbildning av bröstet har man kunnat hitta cancertumörer som kan vara svåra att hitta med mammografi. Simulerade bröstfantomer har ökat både i antal och komplexitet de senaste åren. Bröstfantomen har använts för att validera medicinska avbildningssystem och den största fördelen med modellerna är den korta beräkningstiden. Med tanke på denna fördel av att kunna simulera många bröst på kort tid, samt fördelen med mekanisk avbildning hade det varit fördelaktigt att kombinera dessa två aspekter. I detta projekt simulerades kompression av ett bröst med hjälp av Finita Element Metoden. En tumör lades till i bröstet för att undersöka om de simulerade resultaten av trycket i bröstet överensstämde med klinisk data. Tumörens styvhet, storlek och läge i bröstet varierades. I alla simulerade exempel identifierades lokala områden med högt tryck som överensstämde med tillgänglig klinisk data.A change in stiffness of breast tissue is often connected to a pathological change. Some types of breast cancer such as infiltrating ductal carcinoma can be up to eight times stiffer than fat tissue. It has been found that during compression of the breast there will be a local area of relatively high stress at the breast surface at the location of a tumour. This type of mechanical imaging of the breast has been able to find cancers which can be difficult to find in mammography. Virtual breast phantoms have been growing in number and complexity for the past couple of years. The breast models have been used to validate medical imaging modalities and their great advantage is their low computation time. Considering the advantage of using virtual breast phantoms and mechanical imaging, combining these two aspects could prove to be advantageous. In this thesis a Finite Element model of a breast with a linear elastic material model was subjected to mammographic compression. A tumour was inserted to study the surface pressure values of the breast phantom. As a first step, it was tested how the simulated surface pressure matched the stress patterns seen with mechanical imaging on real breasts. The tumour’s stiffness, size, and location was varied. For all simulated examples, a local area of relatively high stress at the location of the tumour was found. This is in agreement with available clinical data although on the lower end of the reported stress ranges.Simulating compression of a breast can lead to better detection of cancer Cancer is a major cause of death worldwide. For women, breast cancer has the highest frequency of all cancer types and affects roughly 2 million women worldwide every year. Mammographic screening is seen as the golden standard when it comes to the early detection of breast cancer. However, not all cases of cancer are detected as their characteristics are too similar to the background or too small in size to be detected. Moreover, there are also cases in mammography when it is unclear whether a tumour is benign or not. What if there was a way to detect these cancers as well as determine which type of tumour it is? The idea in this project is that it can be solved by "mechanical imaging". Mechanical imaging of the breast has been done by loading the breast between two plates and measuring the surface stress in order to assess its mechanical properties. The reasoning for why it works in detecting cancers it is that tumour tissue is generally stiffer than normal breast tissue. This will result in an area of local high stress on the surface of the breast, at the location of the tumour. What if it was possible t