Search

The University of Johannesburg has integrated serious games into its teaching, exemplified by Codebreakers, a 2D game teaching information theory. While successful, Codebreakers lacked personalisation and used a criticised assessment method based on answer streaks. Knowledge tracing algorithms, known for their effectiveness in intelligent tutoring systems, were considered to address these limitations. This led to the research question: "Can a new serious game be designed, incorporating knowledge tracing algorithms to deliver personalised learning experiences in telecommunications education?" In response, an escape-themed serious game was developed, integrating Bayesian Knowledge Tracing as a statistical student model for personalised learning. This innovative approach combines free-roam gameplay with tailored educational content, significantly advancing serious game design. While primarily aimed at enhancing Codebreakers, this new game contributes substantially to serious game theory by successfully implementing personalised learning within an engaging format. The project showcases the potential of knowledge tracing algorithms in creating adaptive, student-centered learning experiences within the context of educational games. [ABSTRACT FROM AUTHOR]

Background: Assessment of 3-dimensional (3D) femoral head coverage is critical in evaluating, preoperative planning, and treating hip dysplasia. Purpose: To (1) propose a mathematical model to establish 3D femoral head coverage using conventional computed tomography (CT), (2) determine the correlation of 2D parameters with 3D coverage, and (3) characterize the patterns of dysplasia based on 3D morphology. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We identified 30 patients (n = hips) with symptomatic dysplasia and 30 patients (n = hips) without dysplasia. Patients with dysplastic hips were matched with regard to sex, age, and body mass index to those with nondysplastic hips. Preoperative CTs were analyzed using 3D software, and 3D femoral head surface area coverage (FHSAC; in %) was assessed in 4 quadrant zones: anteromedial, anterolateral, posteromedial, and posterolateral. To assess lateral coverage of the femoral head, we introduced the anterolateral femoral head coverage angle (ALFC) and the posterolateral femoral head coverage angle (PLFC). Results: Reduced femoral head coverage was more pronounced in dysplastic versus nondysplastic hips in the anterolateral quadrant (18% vs 40.7%, respectively) and posterolateral quadrant (35.8% vs 56.9%, respectively) (P <.0001 for both). Dysplastic hips had smaller ALFC and PLFC (18.4° vs 38.7°; P <.0001; 47.2° vs 72.3°; P =.0002). Anterolateral and posterolateral FHSAC were strongly correlated with the ALFC (r = 0.88; P <.0001) and the PLFC (r = 0.82; P <.0001) along with the lateral center-edge angle (anterolateral, r = 0.75; P <.0001; posterolateral, r = 0.73; P <.0001). Prediction models established for FHSAC had strong agreement with explanatory CT variables (anterolateral: r = 0.91; P <.0001; posterolateral: r = 0.90; P <.0001). The cutoff values for anterolateral and posterolateral FHSAC were 25% and 41%, respectively. In dysplastic hips, global deficiency was most common (15/30 hips), 9 hips showed an anterolateral deficiency, and 4 hips had a posterolateral deficiency pattern. Conclusion: The ALFC and The PLFC were strongly correlated with 3D lateral FHSAC and were able to predict 3D coverage accurately. [ABSTRACT FROM AUTHOR]

Stent underexpansion in calcified coronary stenosis is an important predictor of major short- and long-term adverse cardiovascular events. In this case, we describe a novel method for assessing stent expansion using 3-dimensional stent reconstruction with C-arm motion compensated computed tomography.

Abstract Deconstructing surgeries into steps and providing instructions with illustrations has been the staple of surgical textbooks for decades. However, it may be difficult for the novice surgeon to interpret 2‐dimensional (2D) illustrations into 3D surgeries. The objective of this study is to create operable models that demonstrate the progression of surgery in 3D and allow for mastering the final steps of the operation first. Mastoidectomy was performed in a stepwise fashion to different end points on 5 identical 3D‐printed temporal bone models to represent 5 major steps of the operation. The drilled models were computed tomography scanned and the subsequent images were used to create 3D model copies of each step. This is the first study to demonstrate that it is possible to create, scan, and copy stepwise, operable, patient‐specific 3D‐printed models, which the trainee can both reference as a 3D dissection guide and can operate on repeatedly and in any order.

Methods for assessing three-dimensional (3D) breast volume are becoming increasingly popular in breast surgery. However, the precision of intraoperative volumetric assessment is still unclear. Until now, only non-validated scanning systems have been used for intraoperative volumetric analyses. This study aimed to assess the feasibility, handling, and accuracy of a commercially available, validated, and portable device for intraoperative 3D volumetric evaluation. All patients who underwent breast surgery from 2020 to 2022 were identified from our institutional database. Intraoperative 3D volumetric assessments of 103 patients were included in this study. Standardized 3D volumetric measurements were obtained 3 months postoperatively to compare the intraoperatively generated volumetric assessment. All of the study participants were women with a mean age of 48.3 ± 14.7 years (range: 20–89). The mean time for intraoperative volumetric assessment was 8.7 ± 2.6 min. The postoperative 3D volumetric assessment, with a mean volume of 507.11 ± 206.29 cc, showed no significant difference from the intraoperative volumetric measurements of 504.24 ± 276.61 cc (p = 0.68). The mean absolute volume difference between the intraoperative simulations and postoperative results was 27.1 cc. Intraoperative 3D volumetric assessment using the VECTRA H2 imaging system seems to be a feasible, reliable, and accurate method for measuring breast volume. Based on this finding, we plan to investigate whether volumetric objective evaluations will help to improve breast symmetry in the future. [ABSTRACT FROM AUTHOR]

Three dimensional models of cell culture enables researchers to recreate aspects of tumour biology not replicated by traditional two dimensional techniques. Here we describe a protocol to enable automated high throughput phenotypic profiling across panels of patient derived glioma stem cell spheroid models. We demonstrate the use of both live/dead cell end-points and monitor the dynamic changes in the cell cycle using cell lines expressing the FUCCI cell cycle reporter. Together, these assays provide additional insight into the mechanism of action of compound treatments over traditional cell viability assay endpoints.

Bulk Dirac Semimetal (BDS) - a three-dimensional counterpart of graphene, prominently known for its topologically protected linear dispersion energy bands embraces remarkable plasmonic responses at terahertz (THz) frequencies, which can be well capitalized for its optoelectronic applications. Recently, we have demonstrated the BDS based THz plasmonic applications such as surface plasmon polariton assisted microparticle sensing, THz waveguiding with curved/bending geometries and all-optical THz logic gates. However, all of the demonstrations were restricted with 2-D BDS geometries where height of the BDS was assumed to be infinity. For practical applications, it is essential to consider the height dimension in device realization. In this work, we demonstrate 3-D numerical modelling results of BDS based THz applications by considering height dimension of the BDS in the design of curved waveguides, sub-wavelength waveguiding in tapered geometries and 3-D XOR logic gate. We anticipate that the above findings manifest BDS as a potential candidate for opening new avenues in the realization of THz optoelectronic devices.

Insoles are used to treat various foot diseases, including plantar foot, diabetic foot ulcers, and refractory plantar fasciitis. In this study, we investigated the effects of 3-dimensional image-based (3-D) insole in healthy volunteers with no foot diseases. Additionally, the comfort of the 3-D insole was compared with that of a custom-molded insole. A singlecenter, randomized, open clinical trial was conducted to address the effectiveness of insole use in a healthy population with no foot or knee disease. Two types of arch support insoles were evaluated for their effectiveness: a 3-D insole and a custom-molded insole. Fifty Korean volunteers participated in the study and were randomly allocated into the "3-D insole" (n = 40) or "custom-molding insole" (n = 10) groups. All subjects wore 3-D insoles or custommolded insoles for 2 weeks. The sense of wearing shoes (Visual Analog Scale [VAS] and score) and fatigue of the foot were used to assess the insole effects at the end of the 2-week study period. The 3-D insole groups showed significantly improved sense of wearing shoes (VAS, p = 0.0001; score, p = 0.0002) and foot fatigue (p = 0.0005) throughout the study period. Although the number of subjects was different, the custom-molding insole group showed no significant changes in the sense of wearing shoes (VAS, 0.1188; score, p = 0.1483). Foot fatigue in the 3-D insole group improved significantly (p = 0.0005), which shows that a 3-D insole might have favorable effects on foot health in a healthy population. [ABSTRACT FROM AUTHOR]

Abstract Background The therapeutic IgG1 anti-CD20 antibody, rituximab (RTX), has greatly improved prognosis of many B-cell malignancies. Despite its success, resistance has been reported and detailed knowledge of RTX mechanisms are lacking. Complement-dependent cytotoxicity (CDC) is one important mode of action of RTX. The aim of this study was to systematically evaluate factors influencing complement-mediated tumor cell killing by RTX. Methods Different RTX isotypes, IgG1, IgG3, IgA1 and IgA2 were evaluated and administered on four human CD20+ B-cell lymphoma cell lines, displaying diverse expression of CD20 and complement-regulatory protein CD59. Complement activation was assessed on lymphoma cells grown in 2 and 3-dimensional (3D) culture systems by trypan blue exclusion. CDC in 3D spheroids was additionally analyzed by Annexin V and propidium iodide staining by flow cytometry, and confocal imaging. Anti-CD59 antibody was used to evaluate influence of CD59 in RTX-mediated CDC responses. Statistical differences were determined by one-way ANOVA and Tukey post hoc test. Results We found that 3 out of 4 lymphomas were sensitive to RTX-mediated CDC when cultured in 2D, while 2 out of 4 when grown in 3D. RTX-IgG3 had the greatest CDC potential, followed by clinical standard RTX-IgG1 and RTX-IgA2, whereas RTX-IgA1 displayed no complement activation. Although the pattern of different RTX isotypes to induce CDC were similar in the sensitive lymphomas, the degree of cell killing differed. A greater CDC activity was seen in lymphoma cells with a higher CD20/CD59 expression ratio. These lymphomas were also sensitive to RTX when grown in 3D spheroids, although the CDC activity was substantially reduced compared to 2D cultures. Analysis of RTX-treated spheroids demonstrated apoptosis and necrosis essentially in the outer cell-layers. Neutralization of CD59 overcame resistance to RTX-mediated CDC in 2D-cultured lymphoma cells, but not in spheroids. Conclusions The results demonstrate that CDC outcome in CD20+ B-cell lymphoma is synergistically influenced by choice of RTX isotype, antigen density, tumor structure, and degree of CD59 expression. Assessment of tumor signatures, such as CD20/CD59 ratio, can be advantageous to predict CDC efficiency of RTX in vivo and may help to develop rational mAbs to raise response rates in patients.

Background: The therapeutic IgG1 anti-CD20 antibody, rituximab (RTX), has greatly improved prognosis of many B-cell malignancies. Despite its success, resistance has been reported and detailed knowledge of RTX mechanisms are lacking. Complement-dependent cytotoxicity (CDC) is one important mode of action of RTX. The aim of this study was to systematically evaluate factors influencing complement-mediated tumor cell killing by RTX.Methods: Different RTX isotypes, IgG1, IgG3, IgA1 and IgA2 were evaluated and administered on four human CD20+ B-cell lymphoma cell lines, displaying diverse expression of CD20 and complement-regulatory protein CD59. Complement activation was assessed on lymphoma cells grown in 2 and 3-dimensional (3D) culture systems by trypan blue exclusion. CDC in 3D spheroids was additionally analyzed by Annexin V and propidium iodide staining by flow cytometry, and confocal imaging. Anti-CD59 antibody was used to evaluate influence of CD59 in RTX-mediated CDC responses. Statistical differences were determined by one-way ANOVA and Tukey post hoc test.Results: We found that 3 out of 4 lymphomas were sensitive to RTX-mediated CDC when cultured in 2D, while 2 out of 4 when grown in 3D. RTX-IgG3 had the greatest CDC potential, followed by clinical standard RTX-IgG1 and RTX-IgA2, whereas RTX-IgA1 displayed no complement activation. Although the pattern of different RTX isotypes to induce CDC were similar in the sensitive lymphomas, the degree of cell killing differed. A greater CDC activity was seen in lymphoma cells with a higher CD20/CD59 expression ratio. These lymphomas were also sensitive to RTX when grown in 3D spheroids, although the CDC activity was substantially reduced compared to 2D cultures. Analysis of RTX-treated spheroids demonstrated apoptosis and necrosis essentially in the outer cell-layers. Neutralization of CD59 overcame resistance to RTX-mediated CDC in 2D-cultured lymphoma cells, but not in spheroids.Conclusions: The results demonstrate that CDC outcome in CD20+ B-cell lymphoma is synergistically influenced by choice of RTX isotype, antigen density, tumor structure, and degree of CD59 expression. Assessment of tumor signatures, such as CD20/CD59 ratio, can be advantageous to predict CDC efficiency of RTX in vivo and may help to develop rational mAbs to raise response rates in patients. [ABSTRACT FROM AUTHOR]

The present studies were conducted to evaluate key serum proteins and other components that mediate anchorage-independent growth (3-D growth) of LNCaP prostate cancer cells as spheroids. The cells were cultured on ultra-low attachment plates in the absence and presence of fetuin-A and with or without extracellular vesicles. The data show that fetuin-A (alpha 2HS glycoprotein) is the serum protein that mediates 3-D growth in these cells. It does so by sequestering extracellular vesicles of various sizes on the surfaces of rounded cells that grow as spheroids. These vesicles in turn transmit growth signals such as the activation of AKT and MAP kinases in a pattern that differs from the activation of these key growth signaling pathways in adherent and spread cells growing in 2-D. In the process of orchestrating the movement and disposition of extracellular vesicles on these cells, fetuin-A is readily internalized in adhered and spread cells but remains on the surfaces of non-adherent cells. Taken together, our studies suggest the presence of distinct signaling domains or scaffolding platforms on the surfaces of prostate tumor cells growing in 3-D compared to 2-D. [ABSTRACT FROM AUTHOR]

Summary: Three-dimensional (3D) bioprinting may overcome challenges in tissue engineering. Unlike conventional tissue engineering approaches, 3D bioprinting has a proven ability to support vascularization of larger scale constructs and has been used for several cardiovascular applications. An overview of 3D bioprinting techniques, in vivo translation, and challenges are described.

Abstract Background The use of 3-dimensional (3D) endoscopic thyroidectomy (ET) has been increasing, but its feasibility and safety have not been well documented for thyroidectomy. Hence, to systematically investigate the comparative outcomes during 3D-ET and 2-dimensional (2D) ET for benign and malignant lesions, we conducted this meta-analysis. Methods Based on the PRISMA guidelines, a systematic database search of the PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), and Chinese Wanfang databases was performed. The eligible studies were published in English and Chinese up to October 2020. The major endpoints evaluated were procedure time, blood loss, postoperative drainage, postoperative hospitalization, postoperative complications, total number of lymph node dissections (LNDs), and total cost. Results A total of 15 relevant studies including 1190 patients (583 for 3D-ET and 607 for 2D-ET) compared the application of 3D and 2D laparoscopic systems in thyroid surgery, of which 8 were endoscopic benign thyroidectomy (EBT) and 7 were endoscopic malignant thyroidectomy (EMT). Our meta-analysis indicated that 3D-ET generally had advantages over 2D-ET in terms of procedure time (P = 0.000), blood loss (P = 0.000), postoperative drainage (P = 0.000), postoperative complications (P = 0.000), and LNDs (P = 0.006). However, there were no significant differences between the two systems in terms of total cost (P = 0.245) or postoperative hospitalization (P = 0.068). Subgroup analysis showed consistency of the overall outcomes in each subset, but a shorter postoperative hospitalization in 3D-EBT was revealed. Conclusions Compared to 2D-ET, 3D endoscopic thyroidectomy is an efficient, safe, and reliable method with better depth perception and stereoscopic vision, and an equally satisfactory outcome. More clinical RCTs with long-term follow-up are required to reproduce these promising results.

Transcatheter therapies to treat tricuspid regurgitation are being developed, but few have attempted the gold standard of surgical repair: ring annuloplasty. We describe the first-ever fully percutaneous implantation of a circumferential, semirigid annuloplasty ring to treat massive secondary tricuspid regurgitation. (Level of Difficulty: Advanced.)

BackgroundAdvances in digital imaging including evolving of 3-dimensional (3D) exoscope has allowed its use as an alternative to microscopes in neurosurgery. The exoscope can concede wide space around the operating table and patient. Here, we show a three-surgeon–six-hand operative approach using a 4K-3D exoscope. Practical advantages and disadvantages of this approach are discussed.Clinical PresentationA 58-year-old male was refered with a 60 mm diameter meningioma in the right frontal convexity. The tumor removal was done by an operator and two assistants with a scrub nurse while viewing images displayed on a 55-inch monitor with integrated 4K and 3D visualization technology retrieved by KINEVO®. Meaningful communication between the operator and two assistants allowed for simultaneous, and precise surgical procedures. Gross total removal was achieved without damaging the brain.ConclusionThe ocular-free, openness of 4K-3D exoscope allows for a three-surgeon–six-handed operation, which leads to simultaneous surgical maneuvers by multiple hands, shorter operative time, flexible/intermittent brain retraction made by two assistants, and educational benefits owing to the surgical procedure being visually shared.

Elbow derangements are common. Clinical examination is supplemented by magnetic resonance imaging (MRI) for optimal diagnostic assessment of such disorders. 3-dimensional (3D) imaging is feasible on newer MR scanners in acceptable acquisition times. Isotropic high-resolution 3D MRI affords multiplanar reconstructions and aids in diagnostic evaluation of elbow disorders and pre-/post-surgical assessments. The article details technical considerations of 3D elbow MRI and discusses its role in diagnostic evaluation of elbow disorders with relevant comparisons to 2D MRI and emphasizes as to how such advanced imaging assists in pre- and post-surgical assessments of tendon and ligament derangements.

Understanding the role of autophagy in cancer has been limited by the inability to measure this dynamic process in formalin-fixed tissue. We considered that 3-dimensional models including ex vivo tumor, such as we have developed for studying mesothelioma, would provide valuable insights. Using these models, in which we could use lysosomal inhibitors to measure the autophagic flux, we sought a marker of autophagy that would be valid in formalin-fixed tumor and be used to assess the role of autophagy in patient outcome. Autophagy was studied in mesothelioma cell lines, as 2-dimensional (2D) monolayers and 3-dimensional (3D) multicellular spheroids (MCS), and in tumor from 25 chemonaive patients, both as ex vivo 3D tumor fragment spheroids (TFS) and as formalin-fixed tissue. Autophagy was evaluated as autophagic flux by detection of the accumulation of LC3 after lysosomal inhibition and as autophagy initiation by detection of ATG13 puncta. We found that autophagic flux in 3D, but not in 2D, correlated with ATG13 positivity. In each TFS, ATG13 positivity was similar to that of the original tumor. When tested in tissue microarrays of 109 chemonaive patients, higher ATG13 positivity correlated with better prognosis and provided information independent of known prognostic factors. Our results show that ATG13 is a static marker of the autophagic flux in 3D models of mesothelioma and may also reflect autophagy levels in formalin-fixed tumor. If confirmed, this marker would represent a novel prognostic factor for mesothelioma, supporting the notion that autophagy plays an important role in this cancer.

Aims The current guidelines on pulmonary hypertension (PH) recommend the use of invasive examination for differentiating between left-sided heart disease-related (post-capillary) and pre-capillary PH. However, atrial sizes are considered markers of ventricular filling pressures. Therefore, we aimed to test the clinical applicability of atrial volumes measured by transthoracic three-dimensional echocardiography (3DE) in differentiating between pre-capillary and post-capillary PH. Methods and results Seventy-five consecutive patients with PH were prospectively examined with transthoracic 3DE. After less than 24 h, the patients underwent right heart catheterization and 3DE and were classified as pre-capillary or post-capillary PH according to the recommendations of the ESC guidelines. The atrial volumes were measured offline with dedicated commercial software. Thirty-eight patients (13 men, age 65 ± 18 year) had pre-capillary PH, and 37 (23 men, age 62 ± year) had post-capillary PH. The mean pulmonary artery pressures were similar in patients with pre-capillary and post-capillary PH (38 [IQR 26, 54] mmHg vs. 41 [IQR 33, 48] mmHg, respectively, P = 0.49). The left atrial indexed maximum (LAVi max) and minimum (LAVi min) volumes were significantly larger in the post-capillary PH patient group than in the pre-capillary PH patient group (LAVi max: 64 ± 32 mL/m² vs. 41 ± 25 mL/m², P = 0.001; LAVi min: 50 ± 22 mL/m² vs. 26 ± 24 mL/m², P < 0.0001). The indexed right atrial minimum volume (RAVi min) was also higher in patients with post-capillary PH (51 ± 27 mL/m² vs. 38 ± 26 mL/m²; P = 0.02). Both the left atrial (LA) and right atrial (RA) volumes, especially the LA minimum volume, correlated with the pulmonary artery wedge pressure (PAWP) (r = 0.62 (P < 0.0001) for LAV min vs. r = 0.49 (P < 0.0001) for LAV max; r = 0.32 (P = 0.005) for RAV min vs. r = 0.24 (P = 0.04) for RAV max). Multivariate logistic regression analysis showed that LAVi min was an independent predictor of post-capillary PH. In the receiver operating characteristic (ROC) curves of parameters predicting the post-capillary PH, the areas under the curve (AUC) for LAVi min, LAVi max, and RAVi min were 0.86 (95% CI, 0.76–0.95), 0.78 (95% CI, 0.67–0.89), and 0.66 (0.53–0.78), respectively. Concerning the performance of the atrial volume ratio for differentiating post-capillary PH, the AUC of the atrial volume ratio was significantly lower [AUC: 0.66 (95% CI, 0.53–0.78)]. The ROC analysis indicated a possible cutoff value of 27.7 mL/m² for LAVi min to predict post-capillary PH (AUC = 0.86; sensitivity = 86%, specificity = 76%). Conclusions The BSA-indexed left atrial minimum volume measured by transthoracic 3DE is a useful parameter for differentiating pre-capillary from post-capillary pulmonary hypertension. [ABSTRACT FROM AUTHOR]

Abstract Background Intraoperative 3-dimensional (3D) navigation is increasingly being used for pedicle screw placement. For this purpose, dedicated mobile 3D C-arms are capable of providing intraoperative fluoroscopy-based 3D image data sets. Modern 3D C-arms have a large field of view, which suggests a higher radiation exposure. In this experimental study we therefore investigate the radiation exposure of a new mobile 3D C-arm with large flat-panel detector to a previously reported device with regular flat-panel detector on an Alderson phantom. Methods We measured the radiation exposure of the Vision RFD 3D (large 30 × 30 cm detector) while creating 3D image sets as well as standard fluoroscopic images of the cervical and lumbar spine using an Alderson phantom. The dosemeter readings were then compared with the radiation exposure of the previous model Vision FD Vario 3D (smaller 20 × 20 cm detector), which had been examined identically in advance and published elsewhere. Results The larger 3D C-arm induced lower radiation exposures at all dosemeter sites in cervical 3D scans as well as at the sites of eye lenses and thyroid gland in lumbar 3D scans. At ​​male and especially female gonads in lumbar 3D scans, however, the larger 3D C-arm showed higher radiation exposures compared with the smaller 3D C-arm. In lumbar fluoroscopic images, the dosemeters near/in the radiation field measured a higher radiation exposure using the larger 3D C-arm. Conclusions The larger 3D C-arm offers the possibility to reduce radiation exposures for specific applications despite its larger flat-panel detector with a larger field of view. However, due to the considerably higher radiation exposure of the larger 3D C-arm during lumbar 3D scans, the smaller 3D C-arm is to be recommended for short-distance instrumentations (mono- and bilevel) from a radiation protection point of view. The larger 3D C-arm with its enlarged 3D image set might be used for long instrumentations of the lumbar spine. From a radiation protection perspective, the use of the respective 3D C-arm should be based on the presented data and the respective application.

Abstract Background This study aimed to investigate dental student’s perception of facial attractiveness with regard to different combinations of anteroposterior malar-jaw positions using 3-dimensional (3-D) reconstructed images of subjects. Methods Two Chinese young adults (1 male and 1 female) with straight profiles and average malar projections were selected for the study. 3-D facial images and cone-beam computed tomography images of these two subjects were superimposed using 3-D imaging software. Lateral and oblique views of nine different images were created by moving the maxillomandibular complex and/or zygomatic bone by 4 mm either forward or backward along the sagittal plane. One hundred three undergraduate dental students (n = 24, 33, and 46 students from the Year 3, 4, and 5, respectively) then scored lateral and 45° oblique view images of the newly reconstructed faces. Results In the present study, images with a neutral malar and retruded jaws were found to be the most attractive in both male and female subjects. In addition, the Protruded malar (PM) group (p

Background: Side branch (SB) occlusion during bifurcation stenting is a serious complication. This study aimed to predict SB compromise (SBC) using optical coherence tomography (OCT)., Methods and results: Among the 168 patients who enrolled in the 3D-OCT Bifurcation Registry, 111 bifurcation lesions were analyzed to develop an OCT risk score for predicting SBC. SBC was defined as worsening of angiographic SB ostial stenosis (≥90%) immediately after stenting. On the basis of OCT before stenting, geometric parameters (SB diameter [SBd], length from proximal branching point to carina tip [BP-CT length], and distance of the polygon of confluence [dPOC]) and 3-dimensional bifurcation types (parallel or perpendicular) were evaluated. SBC occurred in 36 (32%) lesions. The parallel-type bifurcation was significantly more frequent in lesions with SBC. The receiver operating characteristic curve indicated SBd ≤1.77 mm (area under the curve [AUC]=0.73, sensitivity 64%, specificity 75%), BP-CT length ≤1.8 mm (AUC=0.83, sensitivity 86%, specificity 68%), and dPOC ≤3.96 mm (AUC=0.68, sensitivity 63%, specificity 69%) as the best cut-off values for predicting SBC. To create the OCT risk score, we assigned 1 point to each of these factors. As the score increased, the frequency of SBC increased significantly (Score 0, 0%; Score 1, 8.7%; Score 2, 28%; Score 3, 58%; Score 4, 85%; P<0.0001)., Conclusions: Prediction of SBC using OCT is feasible with high probability.

PurposeWe evaluated the survival of patients with muscle invasive bladder cancer undergoing radical cystectomy without neoadjuvant chemotherapy to confirm the utility of existing clinical tools to identify low risk patients who could be treated with radical cystectomy alone and a high risk group most likely to benefit from neoadjuvant chemotherapy.Materials and methodsWe identified patients with muscle invasive bladder cancer who underwent radical cystectomy without neoadjuvant chemotherapy at our institution between 2000 and 2010. Patients were considered high risk based on the clinical presence of hydroureteronephrosis, cT3b-T4a disease, and/or histological evidence of lymphovascular invasion, micropapillary or neuroendocrine features on transurethral resection. We evaluated survival (disease specific, progression-free and overall) and rate of pathological up staging. An independent cohort of patients from another institution was used to confirm our findings.ResultsWe identified 98 high risk and 199 low risk patients eligible for analysis. High risk patients exhibited decreased 5-year overall survival (47.0% vs 64.8%) and decreased disease specific (64.3% vs 83.5%) and progression-free (62.0% vs 84.1%) survival probabilities compared to low risk patients (p

The present studies were conducted to evaluate key serum proteins and other components that mediate anchorage-independent growth (3-D growth) of LNCaP prostate cancer cells as spheroids. The cells were cultured on ultra-low attachment plates in the absence and presence of fetuin-A and with or without extracellular vesicles. The data show that fetuin-A (alpha 2HS glycoprotein) is the serum protein that mediates 3-D growth in these cells. It does so by sequestering extracellular vesicles of various sizes on the surfaces of rounded cells that grow as spheroids. These vesicles in turn transmit growth signals such as the activation of AKT and MAP kinases in a pattern that differs from the activation of these key growth signaling pathways in adherent and spread cells growing in 2-D. In the process of orchestrating the movement and disposition of extracellular vesicles on these cells, fetuin-A is readily internalized in adhered and spread cells but remains on the surfaces of non-adherent cells. Taken together, our studies suggest the presence of distinct signaling domains or scaffolding platforms on the surfaces of prostate tumor cells growing in 3-D compared to 2-D.

Background: The use of 3-dimensional (3D) endoscopic thyroidectomy (ET) has been increasing, but its feasibility and safety have not been well documented for thyroidectomy. Hence, to systematically investigate the comparative outcomes during 3D-ET and 2-dimensional (2D) ET for benign and malignant lesions, we conducted this meta-analysis. Methods: Based on the PRISMA guidelines, a systematic database search of the PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), and Chinese Wanfang databases was performed. The eligible studies were published in English and Chinese up to October 2020. The major endpoints evaluated were procedure time, blood loss, postoperative drainage, postoperative hospitalization, postoperative complications, total number of lymph node dissections (LNDs), and total cost. Results: A total of 15 relevant studies including 1190 patients (583 for 3D-ET and 607 for 2D-ET) compared the application of 3D and 2D laparoscopic systems in thyroid surgery, of which 8 were endoscopic benign thyroidectomy (EBT) and 7 were endoscopic malignant thyroidectomy (EMT). Our meta-analysis indicated that 3D-ET generally had advantages over 2D-ET in terms of procedure time (P = 0.000), blood loss (P = 0.000), postoperative drainage (P = 0.000), postoperative complications (P = 0.000), and LNDs (P = 0.006). However, there were no significant differences between the two systems in terms of total cost (P = 0.245) or postoperative hospitalization (P = 0.068). Subgroup analysis showed consistency of the overall outcomes in each subset, but a shorter postoperative hospitalization in 3D-EBT was revealed. Conclusions: Compared to 2D-ET, 3D endoscopic thyroidectomy is an efficient, safe, and reliable method with better depth perception and stereoscopic vision, and an equally satisfactory outcome. More clinical RCTs with long-term follow-up are required to reproduce these promising results. [ABSTRACT FROM AUTHOR]

Deconstructing surgeries into steps and providing instructions with illustrations has been the staple of surgical textbooks for decades. However, it may be difficult for the novice surgeon to interpret 2-dimensional (2D) illustrations into 3D surgeries. The objective of this study is to create operable models that demonstrate the progression of surgery in 3D and allow for mastering the final steps of the operation first. Mastoidectomy was performed in a stepwise fashion to different end points on 5 identical 3D-printed temporal bone models to represent 5 major steps of the operation. The drilled models were computed tomography scanned and the subsequent images were used to create 3D model copies of each step. This is the first study to demonstrate that it is possible to create, scan, and copy stepwise, operable, patient-specific 3D-printed models, which the trainee can both reference as a 3D dissection guide and can operate on repeatedly and in any order., Competing Interests: None., (© 2024 The Authors. OTO Open published by Wiley Periodicals LLC on behalf of American Academy of Otolaryngology–Head and Neck Surgery Foundation.)

Abstract Background Functional impairment of the aorta is a recognized complication of aortic and aortic valve disease. Aortic strain measurement provides effective quantification of mechanical aortic function, and 3-dimenional (3D) approaches may be desirable for serial evaluation. Computerized tomographic angiography (CTA) is routinely performed for various clinical indications, and offers the unique potential to study 3D aortic deformation. We sought to investigate the feasibility of performing 3D aortic strain analysis in a candidate population of patients undergoing transcatheter aortic valve replacement (TAVR). Methods Twenty-one patients with severe aortic valve stenosis (AS) referred for TAVR underwent ECG-gated CTA and echocardiography. CTA images were analyzed using a 3D feature-tracking based technique to construct a dynamic aortic mesh model to perform peak principal strain amplitude (PPSA) analysis. Segmental strain values were correlated against clinical, hemodynamic and echocardiographic variables. Reproducibility analysis was performed. Results The mean patient age was 81±6 years. Mean left ventricular ejection fraction was 52±14%, aortic valve area (AVA) 0.6±0.3 cm2 and mean AS pressure gradient (MG) 44±11 mmHg. CTA-based 3D PPSA analysis was feasible in all subjects. Mean PPSA values for the global thoracic aorta, ascending aorta, aortic arch and descending aorta segments were 6.5±3.0, 10.2±6.0, 6.1±2.9 and 3.3±1.7%, respectively. 3D PSSA values demonstrated significantly more impairment with measures of worsening AS severity, including AVA and MG for the global thoracic aorta and ascending segment (p

Background: Intraoperative 3-dimensional (3D) navigation is increasingly being used for pedicle screw placement. For this purpose, dedicated mobile 3D C-arms are capable of providing intraoperative fluoroscopy-based 3D image data sets. Modern 3D C-arms have a large field of view, which suggests a higher radiation exposure. In this experimental study we therefore investigate the radiation exposure of a new mobile 3D C-arm with large flat-panel detector to a previously reported device with regular flat-panel detector on an Alderson phantom. Methods: We measured the radiation exposure of the Vision RFD 3D (large 30 × 30 cm detector) while creating 3D image sets as well as standard fluoroscopic images of the cervical and lumbar spine using an Alderson phantom. The dosemeter readings were then compared with the radiation exposure of the previous model Vision FD Vario 3D (smaller 20 × 20 cm detector), which had been examined identically in advance and published elsewhere. Results: The larger 3D C-arm induced lower radiation exposures at all dosemeter sites in cervical 3D scans as well as at the sites of eye lenses and thyroid gland in lumbar 3D scans. At male and especially female gonads in lumbar 3D scans, however, the larger 3D C-arm showed higher radiation exposures compared with the smaller 3D C-arm. In lumbar fluoroscopic images, the dosemeters near/in the radiation field measured a higher radiation exposure using the larger 3D C-arm. Conclusions: The larger 3D C-arm offers the possibility to reduce radiation exposures for specific applications despite its larger flat-panel detector with a larger field of view. However, due to the considerably higher radiation exposure of the larger 3D C-arm during lumbar 3D scans, the smaller 3D Carm is to be recommended for short-distance instrumentations (mono- and bilevel) from a radiation protection point of view. The larger 3D C-arm with its enlarged 3D image set might be used for long instrumentations of the lumbar spine. From a radiation protection perspective, the use of the respective 3D C-arm should be based on the presented data and the respective application. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate dental student's perception of facial attractiveness with regard to different combinations of anteroposterior malar-jaw positions using 3-dimensional (3-D) reconstructed images of subjects. Methods: Two Chinese young adults (1 male and 1 female) with straight profiles and average malar projections were selected for the study. 3-D facial images and cone-beam computed tomography images of these two subjects were superimposed using 3-D imaging software. Lateral and oblique views of nine different images were created by moving the maxillomandibular complex and/or zygomatic bone by 4 mm either forward or backward along the sagittal plane. One hundred three undergraduate dental students (n = 24, 33, and 46 students from the Year 3, 4, and 5, respectively) then scored lateral and 45° oblique view images of the newly reconstructed faces. Results: In the present study, images with a neutral malar and retruded jaws were found to be the most attractive in both male and female subjects. In addition, the Protruded malar (PM) group (p < 0.001), and the Retruded Jaws (RJ) group were rated more attractive (p < 0.001). Furthermore, the Relatively Prominent malar (RP) group was rated more attractive (p < 0.001) when malar-jaw relative positions were compared. Conclusion: This study shows that a neutral or a protruded malar favours facial attractiveness in both Chinese male and female subjects. Therefore, an appropriate relationship between malar projection and lower facial convexity should be taken into consideration while designing the orthodontic/orthognathic treatment plans for enhanced aesthetic outcomes. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: This study uses a three-dimensional energy Doppler technique combined with the Virtual Organ Computer-aided Analysis (VOCAL) method in order to determine the diagnostic threshold of blood flow index in breast tumors to provide a reference for evaluation and treatment options.Materials and Methods: We collected 322 solid lesions which had been operated. Each lesion met the definite pathological diagnosis; collected lesions included 262 cases of benign lesions and 60 cases of malignant lesions. All examinations were performed by using GE LOGIQ E9 with VOCAL software. Volume and four distinct vascular indices of gray mean (MG), power mean, ratio (R), and vascular flow index (VFI) were calculated by using the VOCAL software. Sampling and calculation were repeated three times and the mean value was calculated.Results: The average age and power of the malignant group were greater than those of the benign group, ie p < .01 which had significant differences. The gray mean of the malignant group was lower than that of the benign group, ie p > .05 which had no significant differences between benign and malignant groups. The ratio, vascular flow index and volume had significant differences, i.e. p < .01. The area under the receiver operating characteristic curve (AUC) were 0.864, 0.830, 0.800, 0.758, and 0.764 for age, power, ratio, vascular flow index, and volume, respectively. The research indicators were higher than 50% of the curve showing their diagnostic value. The cut-off points of age, power, ratio, vascular flow index, and volume were 37.5, 26.56, 0.031, 0.846, and 1.75, respectively. Their corresponding sensitivity were 93.3%, 75%, 81.7%, 68.3%, 63.3%, and the specificity were 68.7%, 81%, 70.2%, 75.6%, and 81.7%, respectively. Comparison of vascular indices combined with the Breast imaging reporting and data System (BI-RADS) score and simple BI-RADS method, the AUC of power + BI-RADS, ratio + BI-RADS, VFI + BI-RADS, and BI-RADS alone are 0.928, 0.903, 0.895, and 0.796, respectively, which were higher than 50% of the curve. Sensitivity was 81.7%, 80%, 88.3%, 86.7%, and specificity was 88.5%, 85.5%, 77.1%, 69.5%, respectively. The power + BI-RADS method has the highest AUC among these three methods.Conclusions: Quantitative measurement of blood flow and blood vessel distribution in breast tumors by three-dimensional power Doppler ultrasound combined with the VOCAL method is more accurate and sensitive than the traditional two-dimensional ultrasound. And this method has potential promising applications in many current active research areas, such as the studies of random distribution of intratumoral blood vessels or the normalization of tumor blood vessels. Three-dimensional power Doppler ultrasound combined with the VOCAL method provides a new approach to achieving accurate judgments and the method evaluates the curative effect in breast cancer patients. [ABSTRACT FROM AUTHOR]

Human adipose-derived stromal/stem cells (hASC) are widely used for in vitro modeling of physiologically relevant human adipose tissue. These models are useful for the development of tissue constructs for soft tissue regeneration and 3-dimensional (3D) microphysiological systems (MPS) for drug discovery. In this systematic review, we report on the current state of hASC culture and assessment methods for adipose tissue engineering using 3D MPS. Our search efforts resulted in the identification of 184 independent records, of which 27 were determined to be most relevant to the goals of the present review. Our results demonstrate a lack of consensus on methods for hASC culture and assessment for the production of physiologically relevant in vitro models of human adipose tissue. Few studies have assessed the impact of different 3D culture conditions on hASC adipogenesis. Additionally, there has been a limited use of assays for characterizing the functionality of adipose tissue in vitro. Results from this study suggest the need for more standardized culture methods and further analysis on in vitro tissue functionality. These will be necessary to validate the utility of 3D MPS as an in vitro model to reduce, refine, and replace in vivo experiments in the drug discovery regulatory process.

Introduction: Cross-sectional imaging has been increasingly used in recent years for cardiac and chest evaluation as multiplanar imaging gives excellent image characterization. Multiplanar imaging with excellent soft tissue contrast without radiation risks in MRI signifies its major role in cardiac and chest imaging. Aim: To evaluate the value of 3-Dimensional T2-Weighted Short Inversion Time Inversion Recovery (3D-T2-STIR) gated sequence in cardiac and chest MR imaging. Materials and Methods: A prospective cross-sectional study was conducted in which 41 adult patients who came for chest and cardiac MRI were included. All our patients were imaged on a 3-T clinical scanner and obtained T2-weighted SPACE STIR gated sequence in addition to routine sequences. The image qualities of 3D-T2-SPACE STIR sequences were compared with routine MRI sequences and were scored by two experienced radiologist in blinded fashion as good, fair and poor. Scan time consumption of 3D-T2-SPACE STIR sequences and routine MRI sequences were also done. Results: A 3D T2 SPACE STIR sequences demonstrated comparable image quality in all patients. The level of agreement between the two radiologists on the image qualities of 3DT2-SPACE STIR sequences was excellent. In patients with renal failure and pregnant patients where contrast studies and CT is contraindicated 3D SPACE STIR T2 imaging adds value in diagnosing pulmonary thromboembolism, congenital heart disease, bronchiectasis and consolidation with very less sequence acquisition time, ranging from 1 to 3 minutes. Conclusion: A 3D SPACE STIR MRI sequence is a useful adjunct in cardiac and chest imaging especially in renal failure and pregnant patients where contrast is contraindicated and also time conserving in these patients.

In the past the Vertex Morphing method has mainly been used in the context of optimization of thin walled shell structures or fluid mechanical problems. In this paper an extension of this parameter free shape optimization method to 3-dimensional solid structures based on the free Finite Element code CalculiX is presented. Key element of the whole process is an efficient adjoint sensitivity analysis that can handle many design variables providing gradient information for the response functions of interest, e.g. stresses and mass. Typically, parameter free shape optimal designs result in non-smooth geometries and suffer from mesh dependencies. To avoid these phenomena an intermediate filter operation in combination with several post processing steps of the raw sensitivities is added. In the optimization, the filter size is also used as an additional design parameter controlling the curvature of the optimal shape. In many engineering optimization applications constraints have to be considered. These restrictions are included in the optimization problem by the use of Rosen's gradient projection method. For the successive shape update a pseudo linear-elastic static Finite Element analysis with multiple point constraints and a varying Young's modulus is performed in every design iteration. Finally, the capabilities of the extended Vertex Morphing method are demonstrated for an academic example and a geometrically complex part from aerospace industry. • A gradient-based, parameter free shape optimization method for 3-dimensional solid structures based on the FE-software CalculiX is presented. • Sensitivities are based on an adjoint formulation with an intermediate filter step. • Constraints, e.g. mass of the structure, are taken into account by the gradient projection method. • For the mesh update a pseudo linear equation system is solved with multiple point constraints and a varying Young's modulus gaining a higher level of flexibility w.r.t. the shape change. • The capabilities of the whole optimization process are demonstrated on a geometrically complex part from aerospace industry. [ABSTRACT FROM AUTHOR]

Abstract We completely classify non-spanning 3-polytopes, by which we mean lattice 3-polytopes whose lattice points do not affinely span the lattice. We show that, except for six small polytopes (all having between five and eight lattice points), every non-spanning 3-polytope P has the following simple description: P ∩ Z 3 consists of either (1) two lattice segments lying in parallel and consecutive lattice planes or (2) a lattice segment together with three or four extra lattice points placed in a very specific manner. From this description we conclude that all the empty tetrahedra in a non-spanning 3-polytope P have the same volume and they form a triangulation of P , and we compute the h ⁎ -vectors of all non-spanning 3-polytopes. We also show that all spanning 3-polytopes contain a unimodular tetrahedron, except for two particular 3-polytopes with five lattice points. [ABSTRACT FROM AUTHOR]

Introduction: Cross-sectional imaging has been increasingly used in recent years for cardiac and chest evaluation as multiplanar imaging gives excellent image characterization. Multiplanar imaging with excellent soft tissue contrast without radiation risks in MRI signifies its major role in cardiac and chest imaging. Aim: To evaluate the value of 3-Dimensional T2-Weighted Short Inversion Time Inversion Recovery (3D-T2-STIR) gated sequence in cardiac and chest MR imaging. Materials and Methods: A prospective cross-sectional study was conducted in which 41 adult patients who came for chest and cardiac MRI were included. All our patients were imaged on a 3-T clinical scanner and obtained T2-weighted SPACE STIR gated sequence in addition to routine sequences. The image qualities of 3D-T2-SPACE STIR sequences were compared with routine MRI sequences and were scored by two experienced radiologist in blinded fashion as good, fair and poor. Scan time consumption of 3D-T2-SPACE STIR sequences and routine MRI sequences were also done. Results: A 3D T2 SPACE STIR sequences demonstrated comparable image quality in all patients. The level of agreement between the two radiologists on the image qualities of 3DT2-SPACE STIR sequences was excellent. In patients with renal failure and pregnant patients where contrast studies and CT is contraindicated 3D SPACE STIR T2 imaging adds value in diagnosing pulmonary thromboembolism, congenital heart disease, bronchiectasis and consolidation with very less sequence acquisition time, ranging from 1 to 3 minutes. Conclusion: A 3D SPACE STIR MRI sequence is a useful adjunct in cardiac and chest imaging especially in renal failure and pregnant patients where contrast is contraindicated and also time conserving in these patients. [ABSTRACT FROM AUTHOR]

The development of transcatheter mitral valve replacement therapies requires accurate post-processing analysis tools to provide D-shaped mitral annulus dimensions from 3-dimensional (3D) data. The agreement between two semi-automated, software packages to process 3D transesophageal echocardiography (TEE) data for the measurement of the mitral valve annulus dimensions was evaluated. 3DTEE data of patients with moderate–severe mitral regurgitation (MR) were postprocessed with semi-automated, vendor-independent (VI) software and vendor-specific (VS) software. Both post-processing software provided key measurements for the selection of transcatheter valve prosthesis size: annulus area, annulus circumference and the septal-to-lateral distance of the annulus. The intertrigonal distance was provided only by the VS software. The inter- and intra-observer agreements were assessed with Bland–Altman analysis. Of 105 patients (63.8 ± 11 years, 66% male) with MR, 28 had secondary MR, 45 fibroelastic deficiency, and 32 Barlow’s disease. Using VS software, the dimensions for the overall population were 16.1 ± 4.6 cm2 for annulus area, for circumference 14.4 ± 1.9 cm, intertrigonal distance 3.4 ± 0.5 cm and septal-to-lateral distance 3.8 ± 0.6 cm. Similar dimensions were obtained using VI software: 15.7 ± 4.6 cm2 for annulus area, 14.5 ± 2.0 cm for circumference, and 4.1 ± 0.6 cm for septal-to-lateral distance. The inter- and intra-observer agreement for both software programs was excellent. In conclusion, current post-processing software programs for 3DTEE data of the mitral valve annulus provide good reproducibility of key measurements to select the transcatheter prosthesis size.

The serpentine flow channel can be considered as one of the most common and practical channel layouts for a polymer electrolyte membrane fuel cell (PEMFC) since it ensures an effective and efficient removal of water produced in a cell with acceptable parasitic load. Water management is one of the key issues to improve the cell performance since at low operating temperatures in PEMFC, water vapor condensation starts easily and accumulates the liquid water droplet within the flow channels, thus affecting the chemical reactions and reducing the fuel cell performance. In this article, a comprehensive three dimensional numerical simulation is carried out to understand the water droplet mobility in a serpentine gas flow channel for a wide range of surface properties, inlet air velocities, droplet positions (center or off-center, bottom or top) and droplet sizes by deploying a finite volume based methodology. The liquid-gas interface is tracked following the volume-of-fluid (VOF) method. The droplet transport is found to be greatly influenced by the surface wettability properties, inlet velocities, number of droplets emerged and initial droplet positions. Super hydrophobic surface property is not always preferable for designing the gas flow channels. It depends upon the inlet velocity conditions, droplet positions, number of droplets and surface properties.

Glioblastoma (GBM) is the most aggressive adult primary brain tumor with nearly universal treatment resistance and recurrence. The mainstay of therapy remains maximal safe surgical resection followed by concurrent radiation therapy and temozolomide chemotherapy. Despite intensive investigation, alternative treatment options, such as immunotherapy or targeted molecular therapy, have yielded limited success to achieve long-term remission. This difficulty is partly due to the lack of pre-clinical models that fully recapitulate the intratumoral and intertumoral heterogeneity of GBM and the complex tumor microenvironment. Recently, GBM 3D organoids originating from resected patient tumors, genetic manipulation of induced pluripotent stem cell (iPSC)-derived brain organoids and bio-printing or fusion with non-malignant tissues have emerged as novel culture systems to portray the biology of GBM. Here, we highlight several methodologies for generating GBM organoids and discuss insights gained using such organoid models compared to classic modeling approaches using cell lines and xenografts. We also outline limitations of current GBM 3D organoids, most notably the difficulty retaining the tumor microenvironment, and discuss current efforts for improvements. Finally, we propose potential applications of organoid models for a deeper mechanistic understanding of GBM and therapeutic development., Competing Interests: All authors have no conflict of interests to declare., (© The Author(s) 2023. Published by Oxford University Press.)

An industrial application is presented to validate a finite element analysis of 3-dimensional, nonlinear eddy-current problems with periodic excitation. The harmonic- balance method and the fixed-point technique are applied to get the steady state solution using the finite element method. The losses occurring in steel reinforcements underneath a reactor due to induced eddy-currents are computed and compared to measurements.

Background. Validation of three-dimensional (3D) reconstructions of full dental arches with crowns and roots based on cone beam computed tomography (CBCT) imaging represents a key issue in 3D digital dentistry. Objectives. The aim of the study was to search for the most accurate in vivo windowing-based manual tooth segmentation using CBCT. The null hypothesis was that all applied windowing protocols were equivalent in terms of in vivo tooth volume measurement using CBCT. Material and methods. This retrospective study was based on preoperative CBCT images from patients who underwent further tooth extractions for reasons independent of this study. Written informed consent was obtained from all the participants, and the study was approved by the Ethics Committee of Cliniques Universitaires Saint Luc (Brussels, Belgium). The radiological protocol was I-CAT CBCT, 0.3 mm slice thickness, 8 cm × 16 cm field of view, 120 kVp, and 18 mAs. A total of 36 teeth were extracted from 14 patients between the ages of 18 and 68 years. Using 3D Slicer software, segmentations were performed twice by 2 independent observers, with a 1-month time period between the 2 segmentations to study intra- and inter-observer repeatability and reproducibility. Four windowing protocols (level/window) were applied: 1. 1131/1858, 2. 2224/4095, 3. 1131/4095, and 4. AUTO, an automatic protocol provided by default by the software. A total of 576 segmentations were performed. Tooth volumes were automatically calculated using the software. To compare the volumes obtained from CBCT segmentations with a gold-standard method, we laser-scanned the extracted teeth. Results. Excellent intra- and inter-observer intraclass correlations were found for all of the protocols used. The best windowing protocol was 1131/1858 for both observers. Tooth volumes were obtained by manual segmentation of the CBCT images and using windowing protocol 1131/1858. No significantly different tooth volumes were found by laser scanning. Conclusions. Our null hypothesis was rejected. Only windowing protocol 1131/1858 allowed for significantly closer 3D in vivo segmentation of a tooth compared to I-CAT CBCT, with excellent intra-observer repeatability and inter-observer reproducibility. [ABSTRACT FROM AUTHOR]