| 1. |
- Chowdhury, Manish, et al.
(författare)
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Granulometry-based trabecular bone segmentation
- 2017
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Ingår i: 20th Scandinavian Conference on Image Analysis, SCIA 2017. - Cham : Springer. - 9783319591285 ; , s. 100-108, s. 100-108
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Konferensbidrag (refereegranskat)abstract
- The accuracy of the analyses for studying the three dimensional trabecular bone microstructure rely on the quality of the segmentation between trabecular bone and bone marrow. Such segmentation is challenging for images from computed tomography modalities that can be used in vivo due to their low contrast and resolution. For this purpose, we propose in this paper a granulometry-based segmentation method. In a first step, the trabecular thickness is estimated by using the granulometry in gray scale, which is generated by applying the opening morphological operation with ball-shaped structuring elements of different diameters. This process mimics the traditional sphere-fitting method used for estimating trabecular thickness in segmented images. The residual obtained after computing the granulometry is compared to the original gray scale value in order to obtain a measurement of how likely a voxel belongs to trabecular bone. A threshold is applied to obtain the final segmentation. Six histomorphometric parameters were computed on 14 segmented bone specimens imaged with cone-beam computed tomography (CBCT), considering micro-computed tomography (micro-CT) as the ground truth. Otsu’s thresholding and Automated Region Growing (ARG) segmentation methods were used for comparison. For three parameters (Tb.N, Tb.Th and BV/TV), the proposed segmentation algorithm yielded the highest correlations with micro-CT, while for the remaining three (Tb.Nd, Tb.Tm and Tb.Sp), its performance was comparable to ARG. The method also yielded the strongest average correlation (0.89). When Tb.Th was computed directly from the gray scale images, the correlation was superior to the binary-based methods. The results suggest that the proposed algorithm can be used for studying trabecular bone in vivo through CBCT.
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| 2. |
- Guha, Indranil, et al.
(författare)
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A comparative study of trabecular bone micro-structural measurements using different CT modalities
- 2020
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 65:23, s. 235029-
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Tidskriftsartikel (refereegranskat)abstract
- Osteoporosis, characterized by reduced bone mineral density and micro-architectural degeneration, significantly enhances fracture-risk. There are several viable methods for trabecular bone micro-imaging, which widely vary in terms of technology, reconstruction principle, spatial resolution, and acquisition time. We have performed an excised cadaveric bone specimen study to evaluate different computed tomography (CT)-imaging modalities for trabecular bone micro-structural analysis. Excised cadaveric bone specimens from the distal radius were scanned using micro-CT and four in vivo CT imaging modalities: high-resolution peripheral quantitative computed tomography (HR-pQCT), dental cone beam CT (CBCT), whole-body multi-row detector CT (MDCT), and extremity CBCT. A new algorithm was developed to optimize soft thresholding parameters for individual in vivo CT modalities for computing quantitative bone volume fraction maps. Finally, agreement of trabecular bone micro-structural measures, derived from different in vivo CT imaging, with reference measures from micro-CT imaging was examined. Observed values of most trabecular measures, including trabecular bone volume, network area, transverse and plate-rod micro-structure, thickness, and spacing, for in vivo CT modalities were higher than their micro-CT-based reference values. In general, HR-pQCT-based trabecular bone measures were closer to their reference values as compared to other in vivo CT modalities. Despite large differences in observed values of measures among modalities, high linear correlation (r ∈ [0.94 0.99]) was found between micro-CT and in vivo CT-derived measures of trabecular bone volume, transverse and plate micro-structural volume, and network area. All HR-pQCT-derived trabecular measures, except the erosion index, showed high correlation (r ∈ [0.91 0.99]). The plate-width measure showed a higher correlation (r ∈ [0.72 0.91]) among in vivo and micro-CT modalities than its counterpart binary plate-rod characterization-based measure erosion index (r ∈ [0.65 0.81]). Although a strong correlation was observed between micro-structural measures from in vivo and micro-CT imaging, large shifts in their values for in vivo modalities warrant proper scanner calibration prior to adopting in multi-site and longitudinal studies.
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| 3. |
- Klintström, Benjamin, et al.
(författare)
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Feature space clustering for trabecular bone segmentation
- 2017
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Ingår i: 20th Scandinavian Conference on Image Analysis, SCIA 2017. - Cham : Springer. - 9783319591285 - 9783319591292 ; , s. 65-75
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Konferensbidrag (refereegranskat)abstract
- Trabecular bone structure has been shown to impact bone strength and fracture risk. In vitro, this structure can be measured by micro-computed tomography (micro-CT). For clinical use, it would be valuable if multi-slice computed tomography (MSCT) could be used to analyse trabecular bone structure. One important step in the analysis is image volume segmentation. Previous segmentation techniques have either been computer resource intensive or produced sub-optimal results when used on MSCT data. This paper proposes a new segmentation method that tries to balance good results against computational complexity. Material. Fourteen human radius specimens where scanned with MSCT and segmented using the proposed method as well as two segmentation methods previously used to segment trabecular bone (Otsu and Automated Region Growing (ARG)). The proposed method (named FCH) uses a combination of feature space clustering, edge detection and hysteresis thresholding. For evaluation, we computed correlations with the reference method micro-CT for 7 structure parameters and measured segmentation time. Results. Correlations with micro-CT were highest for FCH in 3 cases, highest for ARG in 3 cases, and in general lower for Otsu. Both FCH and ARG had correlations higher than 0.80 for all parameters, except for trabecular thickness and trabecular termini. FCH was 60 times slower than Otsu, but 5 times faster than ARG. Discussion. The high correlations with micro-CT suggest that with a suitable segmentation method it might be possible to analyse trabecular bone structure using MSCT-machines. The proposed segmentation method may represent a useful balance between speed and accuracy.
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| 4. |
- Klintström, Benjamin, et al.
(författare)
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Photon-counting detector CT and energy-integrating detector CT for trabecular bone microstructure analysis of cubic specimens from human radius
- 2022
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Ingår i: European radiology experimental. - : Springer Nature. - 2509-9280. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Background As bone microstructure is known to impact bone strength, the aim of this in vitro study was to evaluate if the emerging photon-counting detector computed tomography (PCD-CT) technique may be used for measurements of trabecular bone structures like thickness, separation, nodes, spacing and bone volume fraction. Methods Fourteen cubic sections of human radius were scanned with two multislice CT devices, one PCD-CT and one energy-integrating detector CT (EID-CT), using micro-CT as a reference standard. The protocols for PCD-CT and EID-CT were those recommended for inner- and middle-ear structures, although at higher mAs values: PCD-CT at 450 mAs and EID-CT at 600 (dose equivalent to PCD-CT) and 1000 mAs. Average measurements of the five bone parameters as well as dispersion measurements of thickness, separation and spacing were calculated using a three-dimensional automated region growing (ARG) algorithm. Spearman correlations with micro-CT were computed. Results Correlations with micro-CT, for PCD-CT and EID-CT, ranged from 0.64 to 0.98 for all parameters except for dispersion of thickness, which did not show a significant correlation (p = 0.078 to 0.892). PCD-CT had seven of the eight parameters with correlations rho > 0.7 and three rho > 0.9. The dose-equivalent EID-CT instead had four parameters with correlations rho > 0.7 and only one rho > 0.9. Conclusions In this in vitro study of radius specimens, strong correlations were found between trabecular bone structure parameters computed from PCD-CT data when compared to micro-CT. This suggests that PCD-CT might be useful for analysing bone microstructure in the peripheral human skeleton.
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| 5. |
- Klintström, Eva, et al.
(författare)
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Clinical dental cone beam computed tomography - a tool for monitoring trabecular bone structure?
- 2015
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Konferensbidrag (refereegranskat)abstract
- PurposeThe aim of this in vitro study was to develop a method for quantitative assessment of trabecular bone micro-architecture by using three-dimensional image processing. The imaging data were acquired with cone beam computed tomography (CBCT), traditionally used for facial and temporal bone imaging but also applicable for peripheral skeleton, and with a dedicated high resolution peripheral computed tomograph (HRpQCT), used for in vivo measurements in bone research. The data from micro-computed tomography (µCT) was used as reference. Methods & Materials15 bone samples from the radius, were examined by CBCT and HRpQCT at a resolution of 80 and 82 µm, respectively. After segmentation, the bone structure parameters bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), trabecular nodes (Tb.Nd) and trabecular termini (Tb.Tm) were quantified. Calculations were performed on an ordinary PC using a MATLAB developed in house. ResultsCBCT and HRpQCT overestimated BV/TV and Tb.Th approximately three times, compared to µCT. On the other hand Tb.Nd was highly underestimated. All parameters from CBCT were strongly correlated to µCT, with correlation coefficients above 0.91 for all studied parameters (0.92-0.98) except for Tb.Tm with a correlation of 0.83. For HRpQCT the correlations were slightly weaker, varying from 0.78 to 0.95. ConclusionThe strong correlations between bone structure parameters computed from CBCT and µCT suggests that CBCT may be a good alternative to HRpQCT for monitoring trabecular bone microarchitecture in vivo.
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| 6. |
- Klintström, Eva, et al.
(författare)
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Direct estimation of human trabecular bone stiffness using cone beam computed tomography
- 2018
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Ingår i: Oral surgery, oral medicine, oral pathology and oral radiology. - : ELSEVIER SCIENCE INC. - 2212-4403 .- 2212-4411. ; 126:1, s. 72-82
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. The aim of this study was to evaluate the possibility of estimating the biomechanical properties of trabecular bone through finite element simulations by using dental cone beam computed tomography data. Study Design. Fourteen human radius specimens were scanned in 3 cone beam computed tomography devices: 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan), NewTom 5 G (QR Verona, Verona, Italy), and Verity (Planmed, Helsinki, Finland). The imaging data were segmented by using 2 different methods. Stiffness (Young modulus), shear moduli, and the size and shape of the stiffness tensor were studied. Corresponding evaluations by using micro-CT were regarded as the reference standard. Results. The 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan) showed good performance in estimating stiffness and shear moduli but was sensitive to the choice of segmentation method. Newtom 5 G (QR Verona, Verona, Italy) and Verity (Planmed, Helsinki, Finland) yielded good correlations, but they were not as strong as Accuitomo 80 U. Morita MFG., Kyoto, Japan). The cone beam computed tomography devices overestimated both stiffness and shear compared with the micro-CT estimations. Conclusions. Finite element-based calculations of biomechanics from cone beam computed tomography data are feasible, with strong correlations for the Accuitomo 80 scanner a. Morita MFG., Kyoto, Japan) combined with an appropriate segmentation method. Such measurements might be useful for predicting implant survival by in vivo estimations of bone properties.
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| 7. |
- Klintström, Eva, et al.
(författare)
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Predicting Trabecular Bone Stiffness from Clinical Cone-Beam CT and HR-pQCT Data; an In Vitro Study Using Finite Element Analysis
- 2016
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Ingår i: PLOS ONE. - : PLOS one. - 1932-6203. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Stiffness and shear moduli of human trabecular bone may be analyzed in vivo by finite element (FE) analysis from image data obtained by clinical imaging equipment such as high resolution peripheral quantitative computed tomography (HR-pQCT). In clinical practice today, this is done in the peripheral skeleton like the wrist and heel. In this cadaveric bone study, fourteen bone specimens from the wrist were imaged by two dental cone beam computed tomography (CBCT) devices and one HR-pQCT device as well as by dual energy X-ray absorptiometry (DXA). Histomorphometric measurements from micro-CT data were used as gold standard. The image processing was done with an in-house developed code based on the automated region growing (ARG) algorithm. Evaluation of how well stiffness (Young's modulus E3) and minimum shear modulus from the 12, 13, or 23 could be predicted from the CBCT and HR-pQCT imaging data was studied and compared to FE analysis from the micro-CT imaging data. Strong correlations were found between the clinical machines and micro-CT regarding trabecular bone structure parameters, such as bone volume over total volume, trabecular thickness, trabecular number and trabecular nodes (varying from 0.79 to 0.96). The two CBCT devices as well as the HR-pQCT showed the ability to predict stiffness and shear, with adjusted R-2-values between 0.78 and 0.92, based on data derived through our in-house developed code based on the ARG algorithm. These findings indicate that clinically used CBCT may be a feasible method for clinical studies of bone structure and mechanical properties in future osteoporosis research.
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| 8. |
- Klintström, Eva, et al.
(författare)
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Trabecular bone histomorphometric measurements and contrast-to-noise ratio in CBCT
- 2014
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Ingår i: Dento-Maxillo-Facial Radiology. - : British Institute of Radiology. - 0250-832X .- 1476-542X. ; 43:8, s. 20140196-
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to evaluate how imaging parameters at clinical dental CBCT affect the accuracy in quantifying trabecular bone structures, contrast-to-noise ratio (CNR) and radiation dose.Methods: 15 radius samples were examined using CBCT (Accuitomo FPD; J. Morita Mfg., Kyoto, Japan). Nine imaging protocols were used, differing in current, voltage, rotation degree, voxel size, imaging area and rotation time. Radiation doses were measured using a KAP-meter. After segmentation, six bone structure parameters and CNR were quantified. Micro-CT images with an isotropic resolution of 20 microns were used as a gold standard.Results: Structure parameters obtained by CBCT were strongly correlated to those by micro CT, with correlation coefficients .0.90 for all studied parameters. Bone volume and trabecular thickness were not affected by changes in imaging parameters. Increased tube current from 5 to 8 mA, decreased isotropic voxel size from 125 to 80 microns and decreased rotation anglefrom 360° to 180° affected correlations for trabecular termini negatively. Decreasing rotation degree also weakened correlations for trabecular separation and trabecular number at 80 microns voxel size. Changes in the rotation degree and tube current affected CNR significantly. The radiation dose varied between 269 and 1284 mGy cm2.Conclusions: Trabecular bone structure can be accurately quantified by clinical dental CBCT in vitro, and the obtained structure parameters are strongly related to those obtained by micro CT. A fair CNR and strong correlations can be obtained with a low radiation dose, indicating the possibility for monitoring trabecular bone structure also in vivo.
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