The abdominal aorta is the largest blood vessel in the abdomen and the main supplier of blood to the lower body. An abdominal aortic aneurysm (AAA) is an unnatural enlargement of the abdominal aorta, which is a serious condition with a high risk of mortality. If the aneurysm exceeds a certain diameter or growth rate, surgical interventions are justified. Use of a diameter-based criterion has been proven to be inaccurate though since some smaller aneurysms can rupture whilst some larger aneurysms remain quiescent. A biomechanical rupture risk assessment (BRRA) that utilizes the finite element method can be used to evaluate the risk of aneurysm rupture. The BRRA calculates the stresses in the aneurysm based upon CT scans and patients blood pressure. Comparing the stresses with the strength of wall in the aneurysm makes it possible to evaluate the risk of rupture. If the stress exceeds the strength, the aneurysm will rupture. To calculate the strength of the vessel wall, a strength equation is used. The strength equation consists of risk factors such as family history, gender, intra luminal pressure and aneurysm diameter. To individualize the assessment further it would be possible to identify and use other risk factors. Rupture risk factors were searched for through two spate literature searches. To identify the risk factors the search utilized keywords such as “rupture risk factors” and “abdominal aortic aneurysm” together with “peak wall stress” or “wall stress”. The search also used a state of the art article from previous research, which contained a list of risk factors that could be searched for. For a factor to be used in this study they had to be global risk factors. Instead of increasing the risk of rupture in a localised point in the aneurysm, a global factor affects the aneurysm uniformly throughout its entirety. The search focused on statistical trials that evaluate the factors impact on wall stress or wall strength. An AAA wall strength equation was constructed based on the rupture risk factors that were identified. This equation was translated into the Finite element analysis program (FEAP) to evaluate its behaviour. A statistical analysis was performed in Matlab using data from the program A4CLINICS developed by VASCOPS gMBh. Using 41 patients along with known patient characteristics and CT scans Biomechanical rupture risk assessment (BRRA) was conducted using the new strength equation. The assessment resulted in a new peak wall rupture index (PWRI). The resulting data was separated into two groups based upon their volume growth rate, one fast growing and one slow growing group. This separation was done for both the VASCOPS strength equation and the new one. Pearson correlation testing was used to test the correlation between both strength equations and volume growth or diameter growth. To evaluate the sensitivity of the strength equation, receiver operating characteristics (ROC) curves were also used. The PWRI in fast and slow groups were not different (p-values of 0.1257 for VASCOPS and 0.0679 for the new equation). The Pearson correlation coefficients showed a higher correlation between new PWRI and volume growth compared to diameter growth. The new PWRI had a higher sensitivity for predicting the volume growth compared to the diameter growth. Initial volume and diameter had the highest sensitivity of all predictors. The new PWRI could be used to predict volume growth. Volume growth is a potential predictor of aneurysm rupture, which indicates the new PWRI can be used in the BRRA. But to achieve results with statistical significance, new simulations using larger population must be performed and the strength equation must be revised.

Det här examensarbetet består i ett produktutvecklingsprojekt som utfördes i samarbete med Liquid Biopsy AB. Syftet med arbetet var att utveckla ett engångskassettsbaserat produktsystem baserat på företagets patentsökta metod för isolering av cancer celler i suspension, inklusive cirkulerande tumörceller. Liquid Biopsy AB är ett svenskt utvecklingsbolag som baserat på ny och unik teknik, är oberoende av proteinmarkörer, använder cirkulerande tumörceller och andra suspenderade tumörceller för att möjliggöra bättre och billigare cancerdiagnostik. Examensarbetet har fokuserat på utvecklingen av engångskassetten, men parallellt arbete har även utförts med tillhörande basenhet. Ulrich och Eppingers produktutvecklingsprocess har utgjort grunden för den process som följts i arbetet, dock med ökat fokus på testning och utvärdering. För att få en bredare kunskapsbas inleddes arbetet med en marknads- och omvärldsanalys samt informationsinsamling om utmaningar och medicintekniska krav. För att tydligt definiera produktvisionen utfördes även undersökningar med potentiella användarna, om företagets patentsökta metod och befintliga prototyper samt framtida förbättringspotential. Det kassettkoncept som utvecklats bygger på användning av provrör av existerande standard, få tillverkningsprocesser och god användarvänlighet, något som samtliga varit av hög prioritet under arbetet. För att säkerställa att produktens flödessystem fungerar som tänkt utfördes tester under prototypframtagningen. Testningen visade att konceptet fungerar i stort sett som tänkt med avseende på flöden, dock förekom vissa toleransproblem som följd av den valda prototypframtagningsprocessen, och vissa andra viktiga egenskaper återstår att testa. Resultatet av utvecklingsprocessen är en första fysisk prototyp av engångskassetten och en funktionell partiell prototyp av basenheten, motsvarande gränssnittet mot engångkassetten, för att möjliggöra testning av engångskassetten. Slutsatsen av arbetet är att det framtagna produktsystemet har tydliga fördelar gentemot företagets befintliga prototyper: inklusive att en engångskassett framtagits, att denna kan utgöra underlag för en produkt, och att denna bland annat har väsentligt kortare processväg vilken i sin tur borde kunna leda till förkortad processtid. Utförd finansiell analys visar även att framtaget produktsystem kan säljas till konkurrenskraftiga priser och med en betydligt lägre instegskostnad än dagens konkurrerande produkter. / This thesis consists of a product development project conducted in collaboration with Liquid Biopsy AB. The purpose of this work was to develop a disposable cartridge-based product system based on the company’s patent-pending method for isolation of circulating tumor cells and other suspended tumor cells. Liquid Biopsy AB is a Swedish medical technology research company with a unique new rheological technology, that is independent of protein markers, using suspended cancer cells, including circulating tumor cells, allows better and cheaper cancer diagnostics than today. The thesis work has focused on the development of the disposable cassette, but parallel work has also been performed with the associated base unit. Ulrich and Eppingers product development process has made up the basis for the process being followed in the thesis work, with increased focus on testing and evaluation. The work began with a market analysis and information gathering on challenges and medical requirements. Several activities were also carried out in order to clearly define the product vision, including user-surveys, analysis of the company's existing prototypes, as well as potential for future improvements. The developed cartridge concept is based on the use of standard test tubes, few manufacturing processes and user-friendliness which all have been high priorities in this work. The cartridge concept consists essentially of various plastic materials and is adapted for manufacturing by injection molding. To ensure that the product’s flow system was operating as intended, tests were conducted during the prototype phase. Testing showed that the concept design flows largely as intended, yet with some tolerance problems as a result of the selected rapid prototyping process, while other essential properties remain to be tested. The result of the development process is a first physical prototype of the disposable cartridge and a partial functional prototype of the base unit to allow testing with the disposable cartridge. The conclusion of this thesis work is that the developed product system has strong advantages over the company’s existing prototypes, including a first version of a disposable cassette that has potential to form the basis of a mass-producible product, significantly shorter processing route which in turn should allow a reduction of the processing time. Financial analysis also indicates that the designed product systems can be sold at competitive prices and with a significantly lower entry cost than today's rivaling products.