3D Doctor Research Articles

The effect of imaging programs and segmentation methods on the accuracy of volume measurements of teeth

ObjectiveThis study investigated whether there are differences between software programs, voxel sizes, segmentation techniques, and intraoral scanners in terms of volume measurement in incisor teeth. Study DesignThirty extracted teeth were scanned using a 3D intraoral scanner. Physical volumes were measured using the water displacement method (WDM) as the gold standard. Cone Beam Computed Tomography (CBCT) images were taken in two voxel sizes (0.3- 0.4 voxel). The volumes of the teeth were calculated using the manual segmentation technique in the 3D Doctor and ImageJ (Fiji) Program, manual and automatic segmentation methods in the ITK-Snap program, and automatic segmentation methods in the 3D Slicer program. The data were analyzed using the Statistical Package for Social Sciences (SPSS, v 20.0). ResultsThere is a significant difference between WDM and 3D Doctor volume measurements at the voxel size of 0.4 (p <0.05). The 3D Doctor program showed more than 13% difference compared to the WDM. There is no significant difference between WDM, intraoral scanner, ITK-Snap, ImageJ (Fiji), 3D Slicer, and 3D-Doctor volume measurements at the voxel size of 0.3. ConclusionMeasurements with manual segmentation in ITK-Snap and ImageJ programs give the closest results to the physical volume measurements of the teeth. The automatic segmentation method in ITK-Snap and 3D Slicer programs may be preferred due to its ease of use and less time consuming. In the 3D Doctor software, volume measurements tend to increase with larger voxel size. Statement of Clinical RelevanceDifferent software programs, voxel size, and segmentation techniques used in CBCT images affect the measurement results of tooth volumes. Very close to physical volume was obtained with the intraoral scanner. Measurements obtained through manual segmentation yield more accurate results.

Cone beam evaluation of pharyngeal airway space in adult skeletal class II div I and class II div II patients with different growth patterns

Objective: To determine and compare the relationship between pharyngeal volume in subjects with class II div I and div II malocclusions. And To determine the relationship between different growth patterns and pharyngeal volume. Materials and Method: This study was conducted among 60 patients in the age group of 18 to 45 years of North Indian origin with class II malocclusions requiring CBCT, reporting to the department of Orthodontics and Dentofacial Orthopaedics at RUHS College of Dental Sciences, Jaipur out of which 30 were class II div I (15 vertical and 15 horizontal growth pattern) and 30 were class II div II (15 vertical and 15 horizontal growth pattern Cone beam computed tomography scans were taken using Carestream CS9300 imaging system (CS 3D Imaging v3.5.7; Carestream Health Inc New York, USA) using FOV of 17x11 cm. Two characteristics in each cbct were measured using the dr Able ( 3d doctor) software : pharyngeal volume in (cm) cube in relation to type of class II malocclusion and pharyngeal volume in (cm) cube in relation to type of growth pattern in class II malocclusion. Results: No significant difference in pharyngeal volume found between skeletal class II div I and div II group Significantly Reduced pharyngeal volume found in vertical growth pattern group. Conclusion: Pharyngeal volume in class II div II group was less as compared to class II div I group but difference was statistically insignificant Vertical growth pattern patients have lower pharyngeal volume as compared to horizontal growth pattern in both sub divisions of class II malocclusion confirming an association between pharyngeal airway space and a vertical skeletal pattern.

A prospective comparative study of mini-PCNL using Trilogy™ or thulium fibre laser with suction.

There has been recent introduction of novel lithotripters and high-power lasers for stone disintegration. With miniaturization of PCNL, there is need of effective disintegration and faster stone-clearance. This study aimed to evaluate efficiency of Trilogy™ and Thulium fibre laser (TFL) in mini-percutaneous nephrolithotomy (mini-PCNL). This is prospective study comparing efficiency and outcomes of Trilogy™ and TFL in mini-PCNL between January 2019 and February 2020. Primary objective was to compare stone fragmentation rates, with secondary objectives beings stone-free rates and complications. There were 60 mini-PCNL with suction using either Trilogy™ or TFL energy source. Mean stone size and density were 27.60 ± 10.17mm, 22.04 ± 9.69mm (p = 0.05) and 1172.9 ± 313.5HU, 1308.9 ± 333.9HU (p = 0.10) for Trilogy™ and TFL, respectively. Using 3D doctor imaging software from CT images, mean stone volumes were 3718.9 ± 3038.7mm3 for Trilogy™ and 3425.9 ± 3096.1mm3 for TFL(p = 0.77). Using probe-activation time or lasing time, stone-fragmentation rate was 5.98 ± 4.25mm3/sec for Trilogy™ and 3.95 ± 1.00mm3/sec for TFL(p = 0.015). Treatment time (puncture to complete clearance) was 32.48 ± 15.39min for Trilogy™ and 28.63 ± 18.56min for TFL(p = 0.38). Haemoglobin drop was 1.19 ± 0.76gm/dl for Trilogy™ and 0.99 ± 0.74gm/dl for TFL (p = 0.30). Trilogy™ arm had 96.6% complete clearance and TFL had 76.6% in TFL at 48h. One patient in Trilogy™ arm required auxiliary RIRS for residual stone. Both arms had complete stone clearance at 1month follow-up. Trilogy™ arm had 3 Clavien-Dindo grade-II complications while TFL had 2 Clavien-Dindo grade-II complications (UTI requiring antibiotics). There was no blood transfusion in either of arm. Trilogy™ had significantly better stone fragmentation rate than TFL in managing renal stones. However, stone-free rates and complications were comparable for Trilogy™ and TFL.

Comparison of mastoid air cell volume in patients with or without a pneumatized articular tubercle.

PurposeThe aim of this study was to compare mastoid air cell volumes in patients with or without a pneumatized articular tubercle (PAT) on cone-beam computed tomography (CBCT) images.Materials and MethodsThe CBCT images of 224 patients were retrospectively analyzed for the presence of PAT. The Digital Imaging and Communications in Medicine data of 30 patients with PAT and 30 individuals without PAT were transferred to 3D Doctor Software. Mastoid air cell volumes were measured using semi-automatic segmentation on axial sections. Data were analyzed using SPSS version 20.0.ResultsThe patients with PAT and those without PAT had a mean mastoid volume of 6.31±2.86 cm3 and 3.25±1.99 cm3, respectively. There were statistically significant differences in mastoid air cell volumes between patients with and without PAT regardless of sex and mastoid air cell side (P<0.05).ConclusionThe detection of PAT on routine dental radiographic examinations might be a potential prognostic factor that could be used to detect extensive pneumatization in the temporal bone. Clinicians should be aware that there may be widespread pneumatization of mastoid air cells in patients in whom PAT is detected. Advanced imaging should be performed in these cases, and possible complications due to surgical interventions should be considered.

Accuracy of CBCT images in the volumetric assessment of residual root canal filling material: Effect of voxel size.

Our aim was to compare three different voxel sizes of CBCT images for the determination of residual filling material volume in root canals when compared with micro CT. Forty-two root canals of 14 extracted human maxillary molar teeth were retreated by using ProFile® instruments. Images were obtained after retreatment by using ProMax 3D Max CBCT at 3 different voxel sizes (1) High resolution (0.1 mm); (2) High definition (0.15 mm); and (3) Normal resolution (0.2 mm). Two observers measured volumes of residual filling materials in exported CBCT images by means of 3D Doctor Software. Micro CT measurements were served as gold standard. Mann-Whitney U test and Wilcoxon Test were used for the comparison of CBCT and micro CT measurements. Statistical significance was set at P < 0.05. No statistically differences were found between the two observers for all measurements (P > 0.05). There were no significant differences among different CBCT voxel sizes used (0.1 mm, 0.15 mm, and 0.2 mm) (P > 0.05). The Spearman correlation coefficients between CBCT at different voxel sizes significantly highly correlated with micro CT measurements for each observer (P < 0.05). Furthermore, no significant differences were found between the measurements obtained by the two observers in consideration to root canal location (P > 0.05). CBCT images may provide useful information in the volumetric assessment of the amount of residual filling material in root canals for retreatment procedures.

Role of CT and MRI in the design and development of orthopaedic model using additive manufacturing

ObjectiveTo study the role of Computed tomography (CT) and Magnetic resonance imaging (MRI) for design and development of orthopaedic model using additive manufacturing (AM) technologies. MethodsA significant number of research papers in this area are studied to provide the direction of development along with the future scope. ResultsBriefly discussed various steps used to create a 3D model by Additive Manufacturing using CT and MRI scan. These scanning technologies are used to produce medical as well as orthopaedic implants by using AM technologies. The images so produced are exported in different software like OsiriX Imaging Software, 3D slicer, Mimics, Magics, 3D doctor and InVesalius to produce a 3D digital model. Various criteria's achieved by CT and MRI scan for design and development of orthopaedic implant using additive manufacturing are also discussed briefly. AM model created by this process show exact shape, size, dimensions, textures, colour and features. ConclusionAM technologies help to convert the digital model into a 3D physical object, thereby improving the understanding of patient anatomy for treatment as well as for educational purpose. These scanning technologies have various applications to enhance the AM in the field of orthopaedic. In orthopaedic every patient model is a customised unit, sourced from the individual patient. 3D CAD data captured by these scanning technologies are directly exported in standard triangulate language (STL) format for printing by AM technologies. Crossestion of the physical model fabricated by this process shows a patient's anatomy if the model prepared by using the bone-like material.

Accuracy of linear and volumetric measurements of artificial ERR cavities by using CBCT images obtained at 4 different voxel sizes and measured by using 4 different software: an ex vivo research.

To compare the accuracy of linear and volumetric measurements of artificial external root resorption (ERR) cavities by cone beam CT (CBCT) images obtained at four voxel sizes and by using four different software ex vivo. ERR cavities were created on 40 extracted single rooted anterior teeth. Images were obtained by using Planmeca CBCT unit at endo mode (0.075 mm); high-resolution mode (0.1 mm); high-definition mode (0.15 mm) and normal resolution mode (0.2 mm) voxel sizes. Images were analyzed by two observers using four different software (Romexis, 3D Doctor, ITK-SNAP, and OsiriX). (1) Diameter; (2) height; (3) depth; and (4) volume of the ERR were measured. CBCT measurements were then compared with direct physical measurements. ANOVA was used with general linear model analysis. The significance level was set at p < 0.05. One-way ANOVA general linear model analysis showed no significant difference between or within observers for diameter, height, depth and volume measurements (p > 0.05). We found significant differences for diameter and volume measurements among softwares in terms of mean differences as compared to mean standard direct measurements (p < 0.05). We found statistically significant differences among voxel sizes and software for height measurements (p < 0.05). In addition, we found significant differences for diameter and volume measurements (p < 0.05) suggesting more accurate measurements for the cervical region when compared to apical region. Observers using CBCT images obtained at four voxel sizes performed similarly in the quantification of artificial ERR with clinically insignificant distinction between CBCT softwares used.

3D-Printed Nose-to-Larynx Airway Model, Preliminary Study

Background and Objectives Flexible fiberscopy is essential in the examination of the nose to larynx airway. However, the instrument is sensitive to manipulation and can sometimes be damaged when excessive external force is applied. In addition, patients can be injured during fiberscopic examination. In this regard, a airway model mimicking the human airway passage was developed for the education of fiberscopy to minimize the danger to both patient and fiberscope. Materials and Method Neck CT data was used to 3D-print the airway model. Using the 3D doctor software, the outlines of the air-filled cavities were extracted. The outline data was modified to make the inside of the outline empty and the outside filled with 3D ink resin. The airway data was used to 3D-print the replica in three pieces, which were then assembled into one. Flexible laryngoscopic examination of nose to larynx was performed using the nose-to-larynx airway model, and for a male patient enrolled in the study. Virtual endoscopy was performed using the same CT data. The examination data were then compared frame by frame with regards to the shapes and positions of nasal inlet, inferior turbinate, torus tubarius, hypopharynx, epiglottis and vocal cord. Results The airway model was very similar in shape and position of the anatomic landmarks compared with real human airway examined by the fiberscope. Conclusion The results of 3D-printed airway model showed similar shapes as the real human airway, and real time endoscopy could be done using the model. This technique can be extended to make models of tubed organs such as the intestine or the bronchial tree. Key words: Airway model ㆍ Fiberscope ㆍ 3D printer

Volumetric Evaluation of Safe Zone for Bone Harvesting From Symphysis Region by Using Cone Beam Computed Tomography.

The aim of the present study was to retrospectively make a volumetric evaluation of symphysis sites of patients by the use of cone beam computed tomography (CBCT). This retrospective study evaluated dentate symphysis region of the mandibles in CBCT scans taken for different reasons in 90 patients (45 women and 45 men). Three-dimensional (3D) data were obtained using a CBCT device Kodak 9000 3D CMOS sensor with optical fiber. CBCT images were then transferred as digital imaging and communications in medicine files and imported into a volumetric-rendering software 3D DOCTOR (Able Software Corp., Lexington, MA) capable of measurements of vector based-segmentation technology for volumetric measurements. The total average bone volume is 2616.45 mm. Significant differences in average bone volume were found between group I and group IV (P < 0.001). Higher bone volume was obtained in the male groups (2903.01 mm) than in the female groups (2329.88 mm). CBCT is a good candidate for 3D assessment of high-contrast structures in the oral region. We suggest that the use of 3D computed tomography in combination with a software program is a dependable means of measuring the volume of the symphysis bone graft.

Contour interpolated radial basis functions with spline boundary correction for fast 3D reconstruction of the human articular cartilage from MR images.

The aim of this work is to demonstrate a new image processing technique that can provide a "near real-time" 3D reconstruction of the articular cartilage of the human knee from MR images which is user friendly. This would serve as a point-of-care 3D visualization tool which would benefit a consultant radiologist in the visualization of the human articular cartilage. The authors introduce a novel fusion of an adaptation of the contour method known as "contour interpolation (CI)" with radial basis functions (RBFs) which they describe as "CI-RBFs." The authors also present a spline boundary correction which further enhances volume estimation of the method. A subject cohort consisting of 17 right nonpathological knees (ten female and seven male) is assessed to validate the quality of the proposed method. The authors demonstrate how the CI-RBF method dramatically reduces the number of data points required for fitting an implicit surface to the entire cartilage, thus, significantly improving the speed of reconstruction over the comparable RBF reconstruction method of Carr. The authors compare the CI-RBF method volume estimation to a typical commercial package (3d doctor), Carr's RBF method, and a benchmark manual method for the reconstruction of the femoral, tibial, and patellar cartilages. The authors demonstrate how the CI-RBF method significantly reduces the number of data points (p-value < 0.0001) required for fitting an implicit surface to the cartilage, by 48%, 31%, and 44% for the patellar, tibial, and femoral cartilages, respectively. Thus, significantly improving the speed of reconstruction (p-value < 0.0001) by 39%, 40%, and 44% for the patellar, tibial, and femoral cartilages over the comparable RBF model of Carr providing a near real-time reconstruction of 6.49, 8.88, and 9.43 min for the patellar, tibial, and femoral cartilages, respectively. In addition, it is demonstrated how the CI-RBF method matches the volume estimation of a typical commercial package (3d doctor), Carr's RBF method, and a benchmark manual method for the reconstruction of the femoral, tibial, and patellar cartilages. Furthermore, the performance of the segmentation method used for the extraction of the femoral, tibial, and patellar cartilages is assessed with a Dice similarity coefficient, sensitivity, and specificity measure providing high agreement to manual segmentation. The CI-RBF method provides a fast, accurate, and robust 3D model reconstruction that matches Carr's RBF method, 3d doctor, and a manual benchmark method in accuracy and significantly improves upon Carr's RBF method in data requirement and computational speed. In addition, the visualization tool has been designed to quickly segment MR images requiring only four mouse clicks per MR image slice.

The three-dimensional reconstruction and visualization of direct intrahepatic portacaval shunt

ABSTRACT Objective: Transjugular intrahepatic portacaval shunt (TIPS) is a traditional and effective treatment for variceal bleeding in cirrhotic patients with portal hypertension. However, in patients with a Budd-Chiari syndrome or other unaccessible hepatic veins, a direct puncture through the inferior caval vein may be inevitable. Direct intrahepatic portacaval shunt (DIPS) also has several advantages compared with TIPS. So we are expected to explore a digitalized model of DIPS and find the suitable shunt pathway of DIPS. Materials and Methods: We chose four hundred serial sectional images from the internal jugular vein superior margin to the edge interior hepatic from Chinese Visible Human Dataset. Surface and volume reconstruction were performed by 3D Doctor 3.5 software programs(ABLE SOFTWARE). Results: We reconstructed a digitalized model including liver and relevant vessels. It can display distribution characteristics and spatial structure relationship of intrahepatic vessels from any positions and angles. Conclusion: DIPS represents a useful addition to the endovascular techniques for managing complications of portal hypertension. The model of DIPS provides a good 3D morphological reference of image diagnostics and interventional therapy for DIPS.

CBCT quantitative evaluation of mandibular lingual concavities in dental implant patients.

The purpose of this study was to evaluate the prevalence of mandibular lingual concavities and to measure them using CBCT (Cone-Beam Computerized Tomography). In this study, CBCT scans of 200 patients requiring dental implants were assessed for lingual concavities. Reconstructed CBCT images were transferred as DICOM files to the 3D DOCTOR software program, and metric, volumetric, and surface area measurements were obtained. Two-way mixed ANOVA was used to model side (left/right, anterior), measurement type, and gender with side and type taken as within-subject variables, gender as between-subject variables, and age as a covariate. A comparison between the dentate and edentulous groups in the samples with lingual concavities was performed using an unpaired Student's t test. Submandibular concavity mean depth and volume were found to be 2.4 mm and 130.7 mm(3), whereas mean depth and volume of sublingual concavities were found to be 1.3 mm and 26.5 mm(3). Significant inverse ratios were found between age and volume and between age and surface area (p < 0.05). All measurements were higher in males than females, but the differences were not statistically significant. The differences between the presence of concavity (sublingual, right, and left submandibular) and dental status (dentate/edentulous) were statistically insignificant (p > 0.05). Mandibular lingual concavity dimensions were found to vary by age, location, and the presence/absence of teeth. Third party software can be used to generate 3-dimensional models that provide useful information about shape, size, and location of sublingual and submandibular concavities prior to implant placement.

Design and Manufacturing Preparation of a Patient Specific Acetabular Cage

Total hip arthoplasty or hip replacement is today a common and highly successful a surgical procedure. However, in the revision artoplasty the procedure is more complicated, as standard devices have to be adapted to different shapes of acetabular defects, which are patient specific especially when they are bigger and wider spread. This kind of big defects, sever acetabular defects, pelvic discontinuity, defects resulted from tumor problems, protrusion, can usually be addressed with a standard Burch-Schneider Antiprotrusio Cage or a Mueller Ring in order to restore the mechanics and the true center of the hip. This paper proposes a design process and manufacturing preparation for a patient specific acetabular cage. The design is intended to fix problems that standard cages sometimes do not resolve, for example insufficient fixation due to the fact that the inferior flange did not engage the ischium, problems of bone graft resorption and in the same time tries to remain an affordable solution. The design process uses as input information the 3D reconstruction of the patient hip from CT scan. Important parameters like the position of the true center of rotation, acetabular anteversion and inclination are determined and calculated. Other parameters, such as number of fixing screws and their designated holes or the amount of bone to be covered with the custom acetabular cage (fixation surface), are proposed by orthopaedic specialist. The design methodology relays on commercial software, such as Solid Works for CAD, 3D Doctor for 3D bone reconstruction from the CT scans or other software for different file transformations. The model was optimized to be produced through direct metal laser-sintering (DMLS). Regarding the results, the particular implant was designed and optimized for fabrication and it is available to be produced. During the design process, although a systematized process was undertaken and implemented, some activities could not be done in systematic, repeatable way. Nevertheless, a design process strategy was established, so that the design would match the requirements of such implant and also a requirements list for the type and form of information needed for this kind of design. Also, we concluded that using software to automate some of the operations that were done manually by the operator would help decrees the design time and improve the repeatability of the process.

Characteristics of neurovascular compression in facial neuralgia patients by 3D high–resolution MRI and fusion technology

ObjectiveTo evaluate the anatomical characteristics and patterns of neurovascular compression in patients suffering trigeminal neuralgia, using 3D high–resolution magnetic resonance imaging methods and fusion technologies. MethodsThe analysis of the anatomy of the facial nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients for TN. 3D high resolution MRI studies (3D SPGR, T1 enhanced 3D MP-RAGE and T2/T1 3D FIESTA) simultaneous visualization were used to assessed using the software 3D DOCTOR. ResultsIn 93 patients (93%), there were one or several locals of neurovascular compression (NVC). The superior cerebellar artery was involved in 71 cases (76%), the other vessels including the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. The mean distance between NVC and nerve origin site in the brainstem was (3.76 ± 2.90) mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). ConclusionsThis 3D high resolution MRI and image fusion technology could be useful for diagnostic and therapeutic decisions in TN.

Characterization of neurovascular compression in facial neuralgia patients by 3D high-resolution MRI and image fusion technique

ObjectiveTo describe the anatomical characteristics and patterns of neurovascular compression (NVC) in patients suffering trigeminal neuralgia (TN) by 3D high-resolution magnetic resonance imaging (MRI) method and image fusion technique. MethodsThe anatomic structure of trigeminal nerve, brain stem and blood vessel was observed in 100 consecutive TN patients by 3D high resolution MRI (3D SPGR, contrast-enhanced T1 3D MP-RAGE and T2/T1 3D FIESTA). The 3D image sources were fused and visualized using 3D DOCTOR software. ResultsOne or several NVC sites, which usually appeared 0–9.8 mm away from brain stem, were found on the symptomatic side in 93% of the TN cases. Superior cerebellar artery was involved in 76% (71/93) of these cases. The other vessels including antero-inferior cerebellar artery, vertebral artery, basilar artery and veins also contributed to the occurrence of NVC. The NVC sites were found to be located in the proximal segment in 42% of these cases (39/93) and in the distal segment in 45% (42/93). Nerve dislocation or distortion was observed in 32% (30/93). ConclusionsVarious 3D high resolution MRI methods combined with the image fusion technique could provide pathologic anatomic information for the diagnosis and treatment of TN.

A Semi-automatic method for segmentation and 3D modeling of glioma tumors from brain MRI

This work presents an efficient method for volume rendering of glioma tumors from segmented 2D MRI Datasets with user interactive control, by replacing manual segmentation required in the state of art methods. The most common primary brain tumors are gliomas, evolving from the cerebral supportive cells. For clinical follow-up, the evaluation of the preoperative tumor volume is essential. Tumor portions were automatically segmented from 2D MR images using morphological filtering techniques. These segmented tumor slices were propagated and modeled with the software package. The 3D modeled tumor consists of gray level values of the original image with exact tumor boundary. Axial slices of FLAIR and T2 weighted images were used for extracting tumors. Volumetric assessment of tumor volume with manual segmentation of its outlines is a time-consuming process and is prone to error. These defects are overcome in this method. Authors verified the performance of our method on several sets of MRI scans. The 3D modeling was also done using segmented 2D slices with the help of medical software package called 3D DOCTOR for verification purposes. The results were validated with the ground truth models by the Radiologist.

Standard Splenic Volume Estimation in North Indian Adult Population: Using 3D Reconstruction of Abdominal CT Scan Images

A prospective study was carried out to establish normative data for splenic dimensions in North Indian population and their correlation with physical standard on abdominal CT of 21 patients aged between 20 and 70 years having no splenic disorders. Splenic volume was measured by two methods—volume and surface rendering technique of Able 3D doctor software and prolate ellipsoid formula. Volumes measured by both the techniques were correlated with their physical standards. Mean splenic volume was 161.57 ± 90.2 cm3 and range 45.7–271.46 cm3. The volume of spleen had linear correlation with body height (r = 0.512, P < .05). Splenic volume (cm3) = 7 × height (cm) − 961 can be used to generate normal standard volume of spleen as a function of body height in North Indian population (with 95% confidence interval). This formula can be used to objectively measure the size of the spleen in adults who have clinically suspected splenomegaly.

Three-dimensional reconstruction of the superior mediastinum from Chinese Visible Human Female

This research aimed to construct three-dimensional (3D) visible models of the superior mediastinum for anatomic study and surgical approaches to the superior mediastinum. Sectional images of the superior mediastinum were acquired through the Chinese Visible Human Female (VCHF) database. One hundred eighty images of the superior mediastinum were imported into Photoshop CS and the images were converted into a JPEG format. Surface and volume reconstruction were performed by 3D Doctor 3.5 and Amira 4.0 software programs on an ordinary personal computer, respectively. The surface and volume reconstruction of the superior mediastinum were successful. The surface reconstruction model allowed rotation and magnification of the superior mediastinum structures as well as displayed the contours of reconstructed structures individually or as a composite with any other selected structure. Volume reconstruction displayed abundant internal detail of reconstructed images in transverse, coronal, sagittal, and random oblique sections. Three-dimensional, visible models of the superior mediastinum based on the sectional images of VCHF can provide unique insight into the anatomy of superior mediastinum. These models provide an excellent adjunct to the anatomy curriculum in medical schools and an invaluable tool for the practicing surgeon planning an operation in this complex anatomic region.

3D computerized model of endolymphatic hydrops from specimens of temporal bone

Conclusion: The 3D models of endolymphatic and perilymphatic spaces enabled us to obtain normal and pathological volumes of each space and helped us to understand the 3D structure of various parts of the inner ear and of endolymphatic hydrops. Objective: To make a 3D model of the inner ear using sections of temporal bone with and without hydrops. Materials and methods: Every 10th 20 µm thick section of temporal bone was collected from two ears with endolymphatic hydrops and five ears without hydrops. Using ZedView, 3D Doctor, FreeForm as analytical software, a 3D model of the inner ear was obtained by reconstruction of these sections. The volumes of the endolymphatic (EV) and perilymphatic spaces (PV) were calculated in each part of the cochlea and vestibular apparatus including the semicircular canals, but the endolymphatic duct and sac were not included. Results: In normal ears (controls), the average cochlear EV was 5.1 µl and the PV was 41.9 µl, and the average vestibular EV was 24.0 µl and the PV 75.7 µl. In one hydropic ear, the cochlear EV was 17.5 µl, cochlear PV 30.7 µl, vestibular EV 42.5 µl, and vestibular PV 33.4 µl. In the other hydropic ear, cochlear EV was 31.2 µl, cochlear PV 30.1 µl, vestibular EV 25.6 µl, and vestibular PV 71.8 µl.

Identification of a C-shaped Canal System in Mandibular Second Molars—Part III: Anatomic Features Revealed by Digital Subtraction Radiography

The purpose of this study was to investigate the ability of digital subtraction radiography (DSR) to reveal anatomic features of C-shaped canal systems in mandibular second molars with the aid of an intraradicular contrast medium. Thirty mandibular second molars with fused roots were collected and stored in 10% formalin solution. After being scanned with microcomputed tomography (μCT) 20 and reconstructed, the root canals were mechanically and chemically cleaned of their pulp tissue. Buccal-lingual digital radiographic (radiovisiography [RVG]) images were taken with mandibular bone plates for each tooth. After the introduction of contrast medium into canals, RVG images were taken again in the same way as before. The digital images taken before and after contrast medium introduction were overlapped, and the image subtraction was performed by using the 3D Doctor software (Able Software Corp, Lexington, MA). All the subtracted canal images (DSR) and reconstructed canal images based on μCT scanning were classified into three categories (ie, type I, II, and III). The classifications based on reconstructed canal images were used as the standard to evaluate the sensitivity (Se) and specificity (Sp) of DSR classification. The results were subjected to the Wilcoxon statistical test, which showed there was no significant difference between the two classifications (p > 0.05). The DSR classification had a very high Se and Sp in all three categories. It is feasible to use the DSR technique clinically to identify anatomic features of the C-shaped canal system in mandibular second molars.