Synthetic Database of Aortic Morphometry and Hemodynamics: Overcoming Medical Imaging Data Availability.

Modeling of hemodynamics and artificial intelligence have great potential to support clinical diagnosis and decision making. While hemodynamics modeling is extremely time- and resource-consuming, machine learning (ML) typically requires large training data that are often unavailable. The aim of this study was to develop and evaluate a novel methodology generating a large database of synthetic cases with characteristics similar to clinical cohorts of patients with coarctation of the aorta (CoA), a congenital heart disease associated with abnormal hemodynamics. Synthetic data allows use of ML approaches to investigate aortic morphometric pathology and its influence on hemodynamics. Magnetic resonance imaging data (154 patients as well as of healthy subjects) of aortic shape and flow were used to statistically characterize the clinical cohort. The methodology generating the synthetic cohort combined statistical shape modeling of aortic morphometry and aorta inlet flow fields and numerical flow simulations. Hierarchical clustering and non-linear regression analysis were successfully used to investigate the relationship between morphometry and hemodynamics and to demonstrate credibility of the synthetic cohort by comparison with a clinical cohort. A database of 2652 synthetic cases with realistic shape and hemodynamic properties was generated. Three shape clusters and respective differences in hemodynamics were identified. The novel model predicts the CoA pressure gradient with a root mean square error of 4.6 mmHg. In conclusion, synthetic data for anatomy and hemodynamics is a suitable means to address the lack of large datasets and provide a powerful basis for ML to gain new insights into cardiovascular diseases.

[Development of a computed tomography data-based Vibrant Bonebridge viewer]. / Entwicklung eines CT-Daten-basierten Vibrant-Bonebridge-Viewers.

BACKGROUND: Because of the anatomy of the mastoid and the size of the actuator, positioning of the Vibrant Bonebridge B-FMT can be difficult without prior evaluation of the individual computed tomography (CT) scan of the temporal bone. Development of a user-friendly CT data viewer to enable positioning of the B-FMT in the temporal bone model, whilst identifying individual, potential anatomic conflicts and offering possible solutions could provide a useful tool for preoperative positioning. OBJECTIVES: Aim of the study was to define the requirements of a Vibrant Bonebridge viewer and construct a prototype. MATERIALS AND METHODS: Based on a ZIBAmira software version and inclusion of a B-FMT model upon creation of a model of the temporal bone-which allows the intuitive estimation of individual, anatomic conflicts-a Vibrant Bonebridge viewer was constructed. RESULTS: The segmentation time of the individual digital imaging and communications in medicine (DICOM) data set is about 5 min. Positioning within the individual three-dimensional temporal bone model allows quantitative and qualitative estimation of conflicts (sigmoid sinus, middle cranial fossa) and determination of a preferred position for the B-FMT. Lifting of the B-FMT can be simulated with the help of a virtual washer. CONCLUSION: The Vibrant Bonebridge viewer reliably allows simulation of B-FMT positioning. The clinical value of the viewer still has to be evaluated.

A computed tomographic data-based vibrant bonebridge visualization tool.

AIM: Information about the temporal bone size and variations of anatomical structures are crucial for a safe positioning of the Vibrant Bonebridge B-FMT. A radiological based preoperative planning of the surgical procedure decreases the surgical time and minimizes the risk of complications. MATERIALS AND METHODS: We developed a software tool, which allows a catch up of foreign DICOM data based CT temporal bone scans. The individual CT scan is transmitted into a 3D reconstructed pattern of the temporal bone. In this 3D reconstruction the individually favored position of the B- FMT should be found. RESULTS: The software allows a determination of a safe B-FMT position by identifying the individual relation of middle fossa, jugular bulb and external auditory canal. Skull thickness and screw length are contained parameters for the surgical planning. CONCLUSION: An easy to handle software tool allows a radiologically data based safe and fast surgical positioning of the B-FMT.

Improving deformable surface meshes through omni-directional displacements and MRFs.

Deformable surface models are often represented as triangular meshes in image segmentation applications. For a fast and easily regularized deformation onto the target object boundary, the vertices of the mesh are commonly moved along line segments (typically surface normals). However, in case of high mesh curvature, these lines may intersect with the target boundary at "non-corresponding" positions, or even not at all. Consequently, certain deformations cannot be achieved. We propose an approach that allows each vertex to move not only along a line segment, but within a surrounding sphere. We achieve globally regularized deformations via Markov Random Field optimization. We demonstrate the potential of our approach with experiments on synthetic data, as well as an evaluation on 2 x 106 coronoid processes of the mandible in Cone-Beam CTs, and 56 coccyxes (tailbones) in low-resolution CTs.

Registration of different phases of contrast-enhanced CT/MRI data for computer-assisted liver surgery planning: evaluation of state-of-the-art methods.

The exact localization of intrahepatic vessels in relation to a tumour is an important issue in oncological liver surgery. For computer-assisted preoperative planning of surgical procedures high quality vessel models are required. In this work we show how to generate such models on the basis of registered CT or MRI data at different phases of contrast agent propagation. We combine well-established intensity-based rigid and non-rigid registration approaches using Mutual Information as distance measure with different masking strategies as well as intensity inhomogeneity correction for MRI data. Non-rigid deformations are modelled by multilevel cubic B-splines. Quantitative evaluations of 5 MRI and 5 CT image pairs show that the liver moves rigidly 7.2 (+/- 4.2) mm on average, while the remaining non-rigid deformations range from 1.4-3 mm. As a result we find that masked rigid registration is necessary and in many cases also sufficient on clinical data. After non-rigid registration the matching shows no deviations in most cases.

Technical aspects and results of surgery for craniosynostosis.

BACKGROUND: The timing and extent of surgery continue to be a matter of discussion in current craniosynostosis management. PATIENTS AND METHODS: We retrospectively reviewed the first 159 children seen from 1996 to 2000 of a total of 243 patients presenting with suspected craniosynostosis. We did not establish a surgical indication in 74 children (47%), either because their malformations were of different origin without associated craniosynostosis (11/7%) or they presented with only mild clinical manifestations of sutural synostosis (63/40%). In 85 cases (53%), we established a surgical indication. Parents did not follow our recommendation in two cases (1%). In 83 cases, we performed diagnosis-related remodeling at the age of 4-12 months. Demographic data, clinical follow-up findings, and regular photo documentation were analyzed. RESULTS: After a mean follow-up of 3 years and 8 months, the results were satisfactory in 68 cases (82%). Of 15 cases (18%) with only limited improvement, two children were submitted to a second intervention. Another two children had to be reoperated on immediately for insufficient hemostasis. In the largest subgroup of children (47) with sagittal synostosis, there was no difference in outcome between surgery performed before and after 6 months of age. DISCUSSION: Surgical indication and assessment of results are based on subjective criteria which limit the comparison with the literature. Our results correspond to those of similar published series. Most of the unfavorable results could be attributed either to inadequate adaptation of the surgical technique to the individual form of the malformation or to a significant secondary loss of correction in multi-sutural synostosis. CONCLUSIONS: The overall results of surgery within the first year of life were satisfactory in 82%. Standard procedures need to be adapted carefully to the individual form of craniosynostosis to avoid unfavorable results. We therefore propose a new surgical technique based on a statistically averaged modular system of skull models to replace freehand remodeling.