The Application Of CT In Intracranial Aneurysms

Part Ⅰ:Radiation Dose and Image Quality of 70 kVp Cerebral CT Angiography with Optimized Sinogram-affirmed Iterative Reconstruction:Comparison with 120 kVp Cerebral CT AngiographyObjective:To evaluate radiation dose, image quality, and optimal level of sinogram-affirmed iterative reconstruction (SAFIRE) of cerebral CT angiography (CTA) at 70 kVp.Materials and methods:One hundred patients were prospectively classified into two groups:Group A (n=50),70 kVp cerebral CTA with 5 levels of SAFIRE reconstruction (S1-S5) and Group B (n=50),120 kVp with filtered back projection (FBP). CT values, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the internal carotid artery (IC A) and middle cerebral artery (MCA) were measured. Subjective image quality was evaluated. Effective dose (ED) was calculated.Results:CT values and noise of ICA and MCA in Group A were higher than those of Group B (all p<0.001) while the SNRICA, SNRMCA, CNRICA, and CNRMCA of Group A at S4-5 were equal (p>0.05) or higher than in Group B (p<0.05). There was no difference in overall image quality between Group A S3-5 and Group B (p>0.05). ED was 0.2±0.0 mSv for Group A with 80% ED reduction in comparison to Group B.Conclusion:Cerebral CTA at 70 kVp is feasible, allowing for substantial dose reduction. SAFIRE S4 level is recommended to obtain optimal image quality. KeyPart Ⅱ:The influence of CT, MR,3DRA on the morphology and hemodynamics of intracranial aneurysms:Comparative studyObjective:To assess the impact of the imaging technique on image-based computational hemodynamic simulations of intracranial aneurysms.Materials and methods:Retrospective analysis of clinical data of 10 cases of intracranial aneurysm patients, each patient underwent CTA, MRA,3DRA, respectively. To compare the hemodynamic parameters and morphology of the model of the 30 aneurysms based on CTA, MRA,3DRA, respectively.Results:In the morphological parameters, compared with DM, CM had the very similar geometry with biggest difference less than 25%, except for the parameter of NA. The maximum difference did not exceed 30% between MM and DM; In the distribution of the Hausdorff surface distance, compared with DM, The average surface distance of CM (0.25±0.07) is smaller than that of MM (0.36±0.1); All of the three models (DM, CM and MM) shared a similar distribution of the three hemodynamic parameters:low AWSS at the sack, high OSI at the body and high AWSSG at the neck. All of the three models (DM, CM and MM) had the same FP (unchanging direction of inflow jet with single stable vortex), same IS (large) and same JS (large).Conclusion:The visual categorization of flow characteristics,the morphological and hemodynamic analysis results were mostly reproduced among 3DRA, MRA, CTA in vivo.Part Ⅲ:Hemodynamic characteristics of large unruptured internal carotid artery aneurysms:a case control studyObjective:To Study on the relationship between the internal carotid artery aneurysm hemodynamics and rupture state.Materials and methods:Retrospective analysis of 11 cases of rupture of the internal carotid artery aneurysm patients, according to medical history, clinical symptoms and CTA performance 11 cases were divided into ruptured group (n=4) and unruptured group (n=7). The models were reconstructed based on CTA image of 11 aneurysms model reconstruction to compare hemodynamic parameters between two groups.Results:AWSS and AWSSG values (1.15±0.35,5770.85±1787.59) of rupture group is lower than those of the unruptured group (4.52±3.2,26099.62±11188.5, P<0.05), but there was no difference between the two groups in OSI (0.43±0.5,0.48±0.14, p=0.077).Conclusion:The low wall shear stress, low wall shear stress gradient, irregular shape wasrelated to the rupture of large unruptured aneurysms in the internal carotid artery.