The paranasal sinuses: three-dimensional reconstruction, photo-realistic imaging, and virtual endoscopy.

BACKGROUND: The purpose of the study was to create computer-aided design models of the paranasal sinuses (frontal, maxillary, and sphenoid) and to perform virtual endoscopy (VE) to them by using virtual reality modelling language technique. MATERIALS AND METHODS: The visible human dataset was used as the input imaging data. The Surfdriver software package was applied on these images to reconstruct the paranasal sinuses as 3-dimensional (3D) computer-aided design models. These models were post-processed in Cinema 4D to perform the photorealistic imaging and VE of the paranasal sinuses. RESULTS: The volumes of the maxillary sinuses were 24747.89 mm³ on the right and 29008.78 mm³ on the left. As for sphenoidal sinuses, an enormous variation was seen between the right and left cavities. The sphenoidal sinuses were 1995.90 mm3 on the right and 10228.93 mm³ on the left while the frontal sinuses were 20805.67 mm³ on the right and 18048.85 mm³ on the left. The largest sinus was left maxillary sinus by volume. Right frontal sinus was the largest sinus by surface area. It was calculated as 6002.73 mm². Our methodological outcomes proved that Surfdriver and Cinema 4D pair could be reliably used for 3D reconstructions, photo realistic imaging and creating 3D virtual environments from the serial sections of the anatomical structures. CONCLUSIONS: This technique allows students, researchers, and surgeons to perform noninvasive visualisation, simulation, and precise quantitative measurements of internal structures of the body. It was developed as a complementary tool for endoscopic surgery. It could be especially preferable for the patients who could not tolerate flexible or rigid endoscopy.

Stereolithographic biomodelling to create tangible hard copies of the ethmoidal labyrinth air cells based on the visible human project.

Rapid prototyping (RP), or stereolithography, is a new clinical application area, which is used to obtain accurate three-dimensional physical replicas of complex anatomical structures. The aim of this study was to create tangible hard copies of the ethmoidal labyrinth air cells (ELACs) with stereolithographic biomodelling. The visible human dataset (VHD) was used as the input imaging data. The Surfdriver software package was applied to these images to reconstruct the ELACs as three-dimensional DXF (data exchange file) models. These models were post-processed in 3D-Doctor software for virtual reality modelling language (VRML) and STL (Standard Triangulation Language) formats. Stereolithographic replicas were manufactured in a rapid prototyping machine by using the STL format. The total number of ELACs was 21. The dimensions of the ELACs on the right and left sides were 52.91 x 13.00 x 28.68 mm and 53.79 x 12.42 x 28.55 mm, respectively. The total volume of the ELACs was 4771.1003 mm(3). The mean ELAC distance was 27.29 mm from the nasion and 71.09 mm from the calotte topologically. In conclusion, the combination of Surfdriver and 3D-Doctor could be effectively used for manufacturing 3D solid models from serial sections of anatomical structures. Stereolithographic anatomical models provide an innovative and complementary tool for students, researchers, and surgeons to apprehend these anatomical structures tangibly. The outcomes of these attempts can provide benefits in terms of the visualization, perception, and interpretation of the structures in anatomy teaching and prior to surgical interventions.

The claustrum: three-dimensional reconstruction, photorealistic imaging, and stereotactic approach.

The purpose of this study was to reveal the computer-aided three-dimensional (3D) appearance, the dimensions, and neighbourly relations of the claustrum and make a stereotactic approach to it by using serial sections taken from the brain of a human cadaver. The Snake technique was used to carry out 3D reconstructions of the claustra and surrounding structures. The photorealistic imaging and stereotactic approach were rendered by using the Advanced Render Module in Cinema 4D software. The claustrum takes the form of the concavity of the insular cortex and the convexity of the putamen. The inferior border of the claustrum is at about the same level as the bottom edge of the insular cortex and the putamen, but the superior border of the claustrum is at a lower level than the upper edge of the insular cortex and the putamen. The volume of the right claustrum, in the dimensions of 35.5710 mm x 1.0912 mm x 16.0000 mm, was 828.8346 mm(3), and the volume of the left claustrum, in the dimensions of 32.9558 mm x 0.8321 mm x x 19.0000 mm, was 705.8160 mm(3). The surface areas of the right and left claustra were calculated to be 1551.149697 mm2 and 1439.156450 mm(2) by using Surfdriver software. This is the first study reporting the 3D reconstruction and photorealistic imaging of the claustrum of the human brain. This technique enables us to determine the spatial coordinates of the target tissues and to rehearse the surgical procedures for preoperative trajectory planning by using virtual surgery. We believe that this study will be a really useful anatomic guide for neuroscientists and neurosurgeons interested in the claustrum.

Analysis of posterior circulation diameters depending on age, sex and side by computed tomography angiography.

BACKGROUND: Posterior circulation of brain is important because of vital organs' blood supply provided by them. In this study, we evaluate the relationship of posterior circulation measurements with age, gender and side by using computed tomography angiography (CTA) images. MATERIALS AND METHODS: A total 199 brain CTA examinations were retrospectively analysed for all posterior circulation arteries (vertebral artery, basilar artery, posterior cerebral artery [PCA], superior cerebellar artery [SCA], anterior inferior cerebellar artery, and posterior inferior cerebellar artery [PICA]) to compare the difference based on age, gender and side. RESULTS: There is no correlation between age and the mean diameters of all vessels (p > 0.05). The mean diameter of left vertebral artery was higher than right vertebral artery in all genders (p = 0.004 for males and p < 0.001 for females). The mean diameter of left SCA and PICA were higher than right SCA and PICA in females (p = 0.032 and p = 0.027, respectively). The mean diameters of basilar, left PCA, left SCA, left vertebral, right PCA, right SCA, right PICA and right vertebral artery were higher in males and that differences were statistically significant (p < 0.001, p = 0.002, p = 0.006, p = 0.004, p = 0.001, p = 0.003, p = 0.002, and p = 0.006, respectively). CONCLUSIONS: The posterior circulation vessel diameter is not affected by aging. The mean diameters of basilar artery, both PCAs, both SCAs, right PICA, both vertebral arteries were higher in males. The mean diameter of left vertebral artery is higher than that of right vertebral artery in all genders.