The role of implants and implant prostheses on the accuracy and artifacts of cone-beam computed tomography: an in-vitro study
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ABSTRACT:
SUBMITTER: Gurjar B
PROVIDER: S-EPMC10771465 | biostudies-literature | 2024 Jan
REPOSITORIES: biostudies-literature
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Project description:The aim of this study was to determine the accuracy of linear measurements around dental implants when using CBCT unit devices presenting different exposure parameters.Dental implants (n?=?18) were installed in the maxilla of human dry skulls, and images were obtained using two CBCT devices: G1-Care Stream 9300 (70?kVp, 6.3?mA, voxel size 0.18?mm, field of view 8?×?8?cm; Carestream Health, Rochester, NY) and G2-R100 Veraview® (75?kVp, 7.0?mA, voxel size 0.125?mm, field of view 8?×?8?cm; J Morita, Irvine, CA). Measurements of bone thickness were performed at three points located (A) in the most apical portion of the implant, (B) 5?mm above the apical point and (C) in the implant platform. Afterwards, values were compared with real measurements obtained by an optical microscopy [control group (CG)]. Data were statistically analyzed with the significance level of p???0.05.There was no statistical difference for the mean values of bone thickness on Point A (CG: 4.85?±?2.25?mm, G1: 4.19?±?1.68?mm, G2: 4.15?±?1.75?mm), Point B (CG: 1.50?±?0.84?mm, G1: 1.61?±?1.27?mm; G2: 1.68?±?0.82?mm) and Point C (CG: 1.78?±?1.33?mm, G1: 1.80?±?1.09?mm; G2: 1.64?±?1.11?mm). G1 and G2 differed in bone thickness by approximately 0.76?mm for Point A, 0.36?mm for Point B and 0.08?mm for Point C. A lower intraclass variability was identified for CG (Point A?=?0.20?±?0.25; Point B?=?0.15?±?0.20; Point C?=?0.06?±?0.05?mm) in comparison with G1 (Point A?=?0.56?±?0.52; Point B?=?0.48?±?0.50; Point C?=?0.47?±?0.56?mm) and G2 (Point A?=?0.57?±?0.51; Point B?=?0.46?±?0.46; Point C?=?0.36?±?0.31?mm).CBCT devices showed acceptable accuracy for linear measurements around dental implants, despite the exposure parameters used.
| S-EPMC5595033 | biostudies-literature
Project description:ObjectivesTo evaluate the accuracy and reliability of a fully automated landmark identification (ALI) system as a tool for automatic landmark location compared with human judges.Materials and methodsA total of 100 cone-beam computed tomography (CBCT) images were collected. After the calibration procedure, two human judges identified 53 landmarks in the x, y, and z coordinate planes on CBCTs using Checkpoint Software (Stratovan Corporation, Davis, Calif). The ground truth was created by averaging landmark coordinates identified by two human judges for each landmark. To evaluate the accuracy of ALI, the mean absolute error (mm) at the x, y, and z coordinates and mean error distance (mm) between the human landmark identification and the ALI were determined, and a successful detection rate was calculated.ResultsOverall, the ALI system was as successful at landmarking as the human judges. The ALI's mean absolute error for all coordinates was 1.57 mm on average. Across all three coordinate planes, 94% of the landmarks had a mean absolute error of less than 3 mm. The mean error distance for all 53 landmarks was 3.19 ± 2.6 mm. When applied to 53 landmarks on 100 CBCTs, the ALI system showed a 75% success rate in detecting landmarks within a 4-mm error distance range.ConclusionsOverall, ALI showed clinically acceptable mean error distances except for a few landmarks. The ALI was more precise than humans when identifying landmarks on the same image at different times. This study demonstrates the promise of ALI in aiding orthodontists with landmark identifications on CBCTs.
| S-EPMC9374352 | biostudies-literature
Project description:BackgroundTo evaluate whether buccal bone thickness (BBT), implant diameter, and abutment/crown material influence the accuracy of cone-beam computed tomography (CBCT) to determine the buccal bone level at titanium implants.MethodsTwo implant beds (i.e., narrow and standard diameter) were prepared in each of 36 porcine bone blocks. The implant beds were positioned at a variable distance from the buccal bone surface; thus, resulting in three BBT groups (i.e., >0.5 to 1.0; >1.0 to 1.5; >1.5 to 2.0 mm). In half of the blocks, a buccal bone dehiscence of random extent ("depth") was created and implants were mounted with different abutment/crown material (i.e., titanium abutments with a metal-ceramic crown and zirconia abutments with an all-ceramic zirconia crown). The distance from the implant shoulder to the buccal bone crest was measured on cross-sectional CBCT images and compared with the direct measurements at the bone blocks.ResultsWhile abutment/crown material and implant diameter had no effect on the detection accuracy of the buccal bone level at dental implants in CBCT scans, BBT had a significant effect. Specifically, when BBT was ≤1.0 mm, a dehiscence was often diagnosed although not present, that is, the sensitivity was high (95.8%), but the specificity (12.5%) and the detection accuracy (54.2%) were low. Further, the average measurement error of the distance from the implant shoulder to the buccal bone crest was 1.6 mm.ConclusionsBased on the present laboratory study, BBT has a major impact on the correct diagnosis of the buccal bone level at dental titanium implants in CBCT images; in cases where the buccal bone is ≤1 mm thick, detection of the buccal bone level is largely inaccurate.
| S-EPMC8247288 | biostudies-literature
Project description:Background/purposeTo evaluate the measurement accuracy of hard-tissue thicknesses adjacent to dental implants with different thread designs on images obtained from cone beam computed tomography (CBCT) using an in vitro model.Materials and methodsOn 4 × 13-mm implant, the neck of the implant was designed with micro-threads, and the apical part was covered by macro-threads; these implants were placed in a vinyl polysiloxane block that mimicked hard-tissue. Models were prepared with various thicknesses of 2.0, 1.0, 0.5 and 0.3 mm adjacent to the dental implant. Each model was scanned using CBCT, and the thickness of the cortical bone from the outer surface of the micro-threads and macro-threads were recorded. Ground sections were prepared, and the thickness was measured with electronic calipers as the gold standard (GS) measurement.ResultsCBCT measurements of the micro-thread surface were consistently underestimated compared to the GS measurement when the thickness of the hard-tissue-mimicking material was ≤1.0 mm. In comparison, CBCT measurements of the macro-thread surface closely approximated the standard measurement, except when the thickness of the hard-tissue-mimicking material was 0.3 mm. The mean percentage errors from the standard measurement for the 2.0-, 1.0-, 0.5-, and 0.3-mm thickness groups were 4.8%, 16.4%, 37.8%, and 92.6%, respectively, for the micro-thread group, and were 0.6%, 2.9%, 9.5%, and 40.8%, respectively, for the macro-thread group.ConclusionWithin the limitations of this study, we conclude that CBCT may not produce sufficient resolution for thin sections of hard tissue-mimicking materials adjacent to micro-thread surfaces.
| S-EPMC6561864 | biostudies-literature
Project description:ObjectivesThe aim of the present study was to explore the feasibility of ultrasonography (US) for clinical imaging of peri-implant tissues.Material and methodsPatients with ≥1 implant, a cone-beam computed tomography (CBCT) scan, an US scan, and clinical photographs taken during the surgery were included. The crestal bone thickness (CBT) and facial bone level (FBL) were measured on both US and CBCT modalities, and direct FBL measurements were also made on clinical images. US measurements were compared with CBCT and direct readings.ResultsA total of eight implants from four patients were included. For FBL measurements, US and direct (r2 = 0.95) as well as US and CBCT (r2 = 0.85) were highly correlated, whereas CBCT correlated satisfactorily with the direct reading (r2 = 0.75). In one implant without facial bone, CBCT was not able to measure CBT and FBL accurately. The estimated bias for CBT readings was 0.17 ± 0.23 mm (p = .10) between US and CBCT. US blood flow imaging was successfully recorded and showed a wide dynamic range among patients with different degrees of clinical inflammation.ConclusionUS is a feasible method to evaluate peri-implant facial crestal bone dimensions. Additional US features, for example, functional blood flow imaging, may be useful to estimate the extent and severity of inflammation.
| S-EPMC8266744 | biostudies-literature
Project description:Cone-beam computed tomography (CBCT) has been recently used to analyse trabecular bone structure around dental implants. To validate the use of CBCT for three-dimensional (3D) peri-implant trabecular bone morphometry by comparing it to two-dimensional (2D) histology, 36 alveolar bone samples (with implants n=27 vs. without implants n=9) from six mongrel dogs, were scanned ex vivo using a high-resolution (80 µm) CBCT. After scanning, all samples were decalcified and then sectioned into thin histological sections (∼6 μm) to obtain high contrast 2D images. By using CTAn imaging software, bone morphometric parameters including trabecular number (Tb.N), thickness (Tb.Th), separation (Tb.Sp) and bone volume fraction (BV/TV) were examined on both CBCT and corresponding histological images. Higher Tb.Th and Tb.Sp, lower BV/TV and Tb.N were found on CBCT images (P<0.001). Both measurements on the peri-implant trabecular bone structure showed moderate to high correlation (r=0.65-0.85). The Bland-Altman plots showed strongest agreement for Tb.Th followed by Tb.Sp, Tb.N and BV/TV, regardless of the presence of implants. The current findings support the assumption that peri-implant trabecular bone structures based on high-resolution CBCT measurements are representative for the underlying histological bone characteristics, indicating a potential clinical diagnostic use of CBCT-based peri-implant bone morphometric characterisation.
| S-EPMC4472132 | biostudies-other
Project description:ObjectiveTo present and validate an open-source fully automated landmark placement (ALICBCT) tool for cone-beam computed tomography scans.Materials and methodsOne hundred and forty-three large and medium field of view cone-beam computed tomography (CBCT) were used to train and test a novel approach, called ALICBCT that reformulates landmark detection as a classification problem through a virtual agent placed inside volumetric images. The landmark agents were trained to navigate in a multi-scale volumetric space to reach the estimated landmark position. The agent movements decision relies on a combination of DenseNet feature network and fully connected layers. For each CBCT, 32 ground truth landmark positions were identified by 2 clinician experts. After validation of the 32 landmarks, new models were trained to identify a total of 119 landmarks that are commonly used in clinical studies for the quantification of changes in bone morphology and tooth position.ResultsOur method achieved a high accuracy with an average of 1.54 ± 0.87 mm error for the 32 landmark positions with rare failures, taking an average of 4.2 second computation time to identify each landmark in one large 3D-CBCT scan using a conventional GPU.ConclusionThe ALICBCT algorithm is a robust automatic identification tool that has been deployed for clinical and research use as an extension in the 3D Slicer platform allowing continuous updates for increased precision.
| S-EPMC10440369 | biostudies-literature
Project description: Not available
| S-EPMC10763271 | biostudies-literature
Project description:Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 ± 0.09, 0.16 ± 0.07, and 0.05 ± 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 ± 0.22, 0.07 ± 0.25, and -0.79 ± 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 ± 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important.
| S-EPMC4425686 | biostudies-literature
Project description:Background and purposeThe scatter induced image quality degradation of cone-beam computed tomography (CBCT) prevents more advanced applications in radiotherapy. We evaluated the dose calculation accuracy on CBCT of various disease sites using different scatter mitigation strategies.Materials and methodsCBCT scans of two patient cohorts (C1, C2) were reconstructed using a uniform (USC) and an iterative scatter correction (ISC) method, combined with an anti-scatter grid (ASG). Head and neck (H&N), lung, pelvic region, and prostate patients were included. To achieve a high accuracy Hounsfield unit and physical density calibrations were performed. The dose distributions of the original treatment plans were analyzed with the γ evaluation method using criteria of 1%/2 mm using the planning CT as the reference. The investigated parameters were the mean γ (γmean), the points in agreement (Pγ≤1) and the 99th percentile (γ1%).ResultsSignificant differences between USC and ISC in C1 were found for the lung and prostate, where the latter using the ISC produced the best results with medians of 0.38, 98%, and 1.1 for γmean, Pγ≤1 and γ1%, respectively. For C2 the ISC with ASG showed an improvement for all imaging sites. The lung demonstrated the largest relative increase in accuracy with improvements between 48% and 54% for the medians of γmean, Pγ≤1 and γ1%.ConclusionsThe introduced method demonstrated high dosimetric accuracy for H&N, prostate and pelvic region if an ASG is applied. A significantly lower accuracy was seen for lung. The ISC yielded a higher robustness against scatter variations than the USC.
| S-EPMC7807872 | biostudies-literature