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Thermodynamics and structural stability of tissues for bio-imaging analysis – The case of intracranial aneurysm rupture risk assessment
摘要： Based on thermodynamic principles, structure stability analysis like stress response and fracture formation is well established for inorganic but not for organic bio-materials. In this study, three equations were established to assess intracranial aneurysm (IA) rupture risk based on patient's IA and internal carotid artery (ICA) angiography images, by incorporating tissue thermodynamics. Our objectives are: (1) establish foundations to help understand the physics behind the observed morphological changes prior to IA rupture, and (2) provide first-principles equations to aide in rupture risk assessment. Subsequently, we validated the new equations using available experimental and numerical simulation results, and revealed new IA rupture physics. In particular, our models correlated well with most of the available experiment and computer fluid dynamics simulation data. Among the three common structure failure modes, the axial stress and the bending moment loading are the control mechanism. The rupture risk reaches its peak when (1) the aneurysm inclination angle (ω) is close to 63.4°, (2) IA diameter / ICA diameter ?1, and (3) IA length / IA diameter ≈1.6. This study provides strong physical foundations and sound understanding to aid in rupture risk assessment. It presents insights on detailed thermodynamics that govern the previously observed IA rupture behaviors, reported from both experiments and numerical simulations. By integrating angiography images with first-principles tissue thermodynamics, we (1) advance the IA research, which is currently dominated by experimental and imaging-data-statistic approaches, and (2) introduce Calphad research into a new exciting research field - bio-imaging analysis.
关键词： Young's Modulus,Entropy,Thin-walled cylinders,Bio-imaging,Intracranial aneurysm
更新于2025-09-23 15:22:29
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An ellipsoid convex enhancement filter for detection of asymptomatic intracranial aneurysm candidates in CAD frameworks
摘要： Various kinds of enhancement filters have been developed in computer-aided diagnostic (CAD) frameworks for asymptomatic intracranial aneurysms in magnetic resonance angiography (MRA). However, many bending or branching portions on vessels are also enhanced by the conventional filters as false positives in 3.0 T MRA, which can visualize smaller vessels compared with 1.5 T MRA. To overcome this problem, this study focused on developing an ellipsoid convex enhancement (ECE) filter, which can selectively enhance aneurysms while reducing false positive contrasts on bending or branching portions on vessels, for detection of asymptomatic intracranial aneurysm candidates in CAD frameworks. The ECE filter was mathematically designed to enhance various convex regions in the intensity space such as convex aneurysms, in which the ratio of the shortest and longest diameters for aneurysms corresponds to the ratio of reciprocals of the square roots of the first and third eigenvalues of a Hessian matrix. The proposed ECE filter was evaluated by measuring an average contrast for false positive models and free-response receiver operating characteristic curves between two simple CAD frameworks using the ECE and conventional filters based on a leave-one-out-by-patient test. MRA images for thirty patients (male: 10, female: 20; age: 48–86 yr, mean: 69.2) with 31 unruptured aneurysms (longest diameter: 2.0–5.5 mm, mean: 3.7 mm) were selected for this study. The average contrast for false positive models was reduced by 51.4% using the ECE filter, compared with the conventional filter for the convex regions with ratios of the shortest and longest diameters less than 0.4. The number of false positives per case was decreased from 41.1 to 22.8 on average at a sensitivity of 87% by using the ECE filter. The ECE filter would be useful for boosting the performance of the CAD framework of asymptomatic intracranial aneurysms by providing higher contrast aneurysms and lower contrast false positives such as bending or branching portions on vessels.
关键词： unruptured intracranial aneurysm,ellipsoid convex enhancement (ECE) filter,magnetic resonance angiography (MRA),computer-aided diagnosis (CAD)
更新于2025-09-04 15:30:14