scholarly journals Evaluation of three-dimensional acromiohumeral distance in the standing position and comparison with its conventional measuring methods

2020 ◽  
Author(s):  
Yuki Yoshida ◽  
Noboru Matsumura ◽  
Yoshitake Yamada ◽  
Minoru Yamada ◽  
Yoichi Yokoyama ◽  
...  
Keyword(s):  
Supine Position ◽  
Humeral Head ◽  
Three Dimensional ◽  
Standing Position ◽  
Ct Scanner ◽  
Mean Values ◽  
Measuring Methods ◽  
The Mean ◽  
Acromiohumeral Distance ◽  
2D And 3D

Abstract Background: Narrowing of the acromiohumeral distance (AHD) implies a rotator cuff tear. However, conventional AHD measurements using two-dimensional (2D) imaging or with the patient in the supine position might differ from that while standing during daily activity. This study aimed to evaluate the three-dimensional (3D) actual distance between the acromion and humeral head in the standing position and compare the AHD values with those obtained using conventional measuring methods.Methods: Computed tomography (CT) images of 166 shoulders from 83 healthy volunteers (31 male and 52 female; mean age 40.1 ± 5.8 years; age range, 30–49 years) were prospectively acquired in the supine and standing positions using conventional and upright CT scanners, respectively. The minimum distance between the acromion and humeral head on the 3D surface models was considered as the 3D AHD. We measured the 2D AHD on anteroposterior digitally reconstructed radiographs. The AHD values were compared between the supine and standing positions and between the 2D and 3D measurements.Results: The mean values of 2D AHD were 8.8 ± 1.3 mm (range, 5.9–15.4 mm) in the standing position and 8.1 ± 1.2 mm (range, 5.3–14.3 mm) in the supine position. The mean values of 3D AHD were 7.3 ± 1.4 mm (range, 4.7–14.0 mm) in the standing position and 6.6 ± 1.2 mm (range, 4.4–13.7 mm) in the supine position. The values of 3D AHD were significantly lower than those of 2D AHDs in both the standing and supine positions (P < 0.001). The values of 2D and 3D AHDs were significantly lower in the supine position than in the standing position (P < 0.001). Conclusions: This study evaluated the 3D AHD of normal shoulders in the standing position using an upright CT scanner. The present results indicated that assessments in the supine position can underestimate the value of the AHD compared with those made in the standing position and that assessments using 2D analysis can overestimate the value.

scholarly journals Evaluation of three-dimensional acromiohumeral distance in the standing position and comparison with its conventional measuring methods

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Yuki Yoshida ◽  
Noboru Matsumura ◽  
Yoshitake Yamada ◽  
Minoru Yamada ◽  
Yoichi Yokoyama ◽  
...  
Keyword(s):  
Supine Position ◽  
Humeral Head ◽  
Three Dimensional ◽  
Standing Position ◽  
Ct Scanner ◽  
Mean Values ◽  
Measuring Methods ◽  
The Mean ◽  
Acromiohumeral Distance ◽  
2D And 3D

Abstract Background Narrowing of the acromiohumeral distance (AHD) implies a rotator cuff tear. However, conventional AHD measurements using two-dimensional (2D) imaging or with the patient in the supine position might differ from that while standing during daily activity. This study aimed to evaluate the three-dimensional (3D) actual distance between the acromion and humeral head in the standing position and compare the AHD values with those obtained using conventional measuring methods. Methods Computed tomography (CT) images of 166 shoulders from 83 healthy volunteers (31 male and 52 female; mean age 40.1 ± 5.8 years; age range, 30–49 years) were prospectively acquired in the supine and standing positions using conventional and upright CT scanners, respectively. The minimum distance between the acromion and humeral head on the 3D surface models was considered as the 3D AHD. We measured the 2D AHD on anteroposterior digitally reconstructed radiographs. The AHD values were compared between the supine and standing positions and between the 2D and 3D measurements. Results The mean values of 2D AHD were 8.8 ± 1.3 mm (range, 5.9–15.4 mm) in the standing position and 8.1 ± 1.2 mm (range, 5.3–14.3 mm) in the supine position. The mean values of 3D AHD were 7.3 ± 1.4 mm (range, 4.7–14.0 mm) in the standing position and 6.6 ± 1.2 mm (range, 4.4–13.7 mm) in the supine position. The values of 3D AHD were significantly lower than those of 2D AHDs in both the standing and supine positions (P < 0.001). The values of 2D and 3D AHDs were significantly lower in the supine position than in the standing position (P < 0.001). Conclusions This study evaluated the 3D AHD of normal shoulders in the standing position using an upright CT scanner. The present results indicated that assessments in the supine position can underestimate the value of the AHD compared with those made in the standing position and that assessments using 2D analysis can overestimate the value.

scholarly journals Comparisons of acromiohumeral distance measurements between two- and three-dimensional imaging and between the supine and standing positions

2020 ◽  
Author(s):  
Yuki Yoshida ◽  
Noboru Matsumura ◽  
Yoshitake Yamada ◽  
Minoru Yamada ◽  
Yoichi Yokoyama ◽  
...  
Keyword(s):  
Supine Position ◽  
Humeral Head ◽  
Three Dimensional ◽  
Standing Position ◽  
Two Dimensional ◽  
Subacromial Space ◽  
Mean Values ◽  
The Mean ◽  
Acromiohumeral Distance ◽  
2D And 3D

Abstract Background Narrowing of the acromiohumeral distance (AHD) implies a rotator cuff tear. However, AHD measurements on two-dimensional (2D) imaging or with the patient in the supine position might differ from that while standing during daily activity. This study aimed to accurately measure the distance between the acromion and the humeral head on three-dimensional (3D) imaging acquired in the standing position and to compare this with AHD measurements made on images acquired in the supine position and on 2D images. Methods Computed tomography (CT) images of 166 shoulders from 83 healthy volunteers (31 male and 52 female; mean age 40.1 ± 5.8 years; age range, 30–49 years) were prospectively acquired in the supine and standing positions using conventional and upright CT scanners, respectively. AHD was calculated as the minimum distance between the acromion and the humeral head on the 3D surface models. Two-dimensional AHD was measured on anteroposterior digitally reconstructed radiographs images. The AHD values were compared between the supine and standing positions and between the 2D and 3D measurements. Results The mean values of 2D AHD were 8.8 ± 1.3 mm (range, 5.9–15.4 mm) in the standing position and 8.1 ± 1.2 mm (range, 5.3–14.3 mm) in the supine position. The mean values of 3D AHD were 7.3 ± 1.4 mm (range, 4.7–14.0 mm) in the standing position and 6.6 ± 1.2 mm (range, 4.4–13.7 mm) in the supine position. The values of 3D AHD were significantly lower than those of 2D AHDs in both the standing and supine positions (P < 0.001). The values of 2D and 3D AHDs were significantly lower in the supine position than in the standing position (P < 0.001). Conclusions The present results indicated that assessments in the supine position can underestimate the value of the AHD compared with those made in the standing position and that assessments using 2D analysis can overestimate the value. It is necessary to understand that the anatomical distance of the subacromial space changes with images and gravity.

scholarly journals The correlation between the three-dimensional radiolucency area around the crown of impacted maxillary canines and dentigerous cysts

2020 ◽  
Vol 49 (4) ◽  
pp. 20190402
Author(s):  
Junliang Chen ◽  
Dongmei Lv ◽  
MingXia Li ◽  
Wei Zhao ◽  
Yun He
Keyword(s):  
Cone Beam Ct ◽  
Dentigerous Cyst ◽  
Three Dimensional ◽  
Cone Beam ◽  
Hard Tissue ◽  
Mean Values ◽  
Dentigerous Cysts ◽  
Impacted Canine ◽  
The Mean ◽  
Surgical Operations

This study aimed to reveal the correlation between the radiolucency area around the crown of impacted maxillary canines and dentigerous cysts using cone beam CT (CBCT). CBCT data were obtained from patients with impacted maxillary canines. Three points of five areas (tooth cusp area and buccal, lingual, mesial and distal areas of the crown) were randomly selected, and the distance between the point and the surrounding hard tissue was measured respectively. The mean values were recorded as the radiolucency area. These results were compared with the occurrence of dentigerous cysts during surgery. 58 patients with 76 impacted maxillary canines were included. 14 of the 76 impacted canines were accompanied by cysts (18.42%). With the increase in the thickness of the radiolucency area, the incidence of cysts was significantly increased (p < 0.05). No cysts were found in the compacted canines with 0–1 mm thickness of the radiolucency area. The highest incidence (71.43%) was observed in canines with 3–4 mm thickness of the radiolucency area. This study found that the thickness of the radiolucency area around the crown of the maxillary impacted canine was closely related to the occurrence of dentigerous cysts. CBCT can be used to estimate the occurrence possibility of dentigerous cyst and guide surgical operations.

scholarly journals Vectors of subsurface stormflow in a layered hillslope during runoff initiation

2006 ◽  
Vol 10 (3) ◽  
pp. 309-320 ◽  
Author(s):  
M. Retter ◽  
P. Kienzler ◽  
P. F. Germann
Keyword(s):  
Three Dimensional ◽  
Volume Flux ◽  
Wetting Front ◽  
Experimental Assessment ◽  
Mean Values ◽  
Top Soil ◽  
Wave Guides ◽  
The Mean ◽  
Vector Approach

Abstract. The focus is the experimental assessment of in-situ flow vectors in a hillslope soil. We selected a 100 m2 trenched hillslope study site. During prescribed sprinkling an obliquely installed TDR wave-guide provides for the velocity of the wetting front in its direction. A triplet of wave-guides mounted along the sides of an hypothetical tetrahedron, with its peak pointing down, produces a three-dimensional vector of the wetting front. The method is based on the passing of wetting fronts. We analysed 34 vectors along the hillslope at distributed locations and at soil depths from 11 cm (representing top soil) to 40 cm (close to bedrock interface). The mean values resulted as follows vx=16.1 mm min-1, vy=-0.2 mm min-1, and vz=11.9 mm min-1. The velocity vectors of the wetting fronts were generally gravity dominated and downslope orientated. Downslope direction (x-axis) dominated close to bedrock, whereas no preference between vertical and downslope direction was found in vectors close to the surface. The velocities along the contours (y-axis) varied widely. The Kruskal-Wallis tests indicated that the different upslope sprinkling areas had no influence on the orientation of the vectors. Vectors of volume flux density were also calculated for each triplet. The lateral velocities of the vector approach are compared with subsurface stromflow collected at the downhill end of the slope. Velocities were 25-140 times slower than lateral saturated tracer movements on top of the bedrock. Beside other points, we conclude that this method is restricted to non-complex substrate (skeleton or portion of big stones).

scholarly journals The 3D Tele Motion Tracking for the Orthodontic Facial Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Stefano Mummolo ◽  
Alessandro Nota ◽  
Enrico Marchetti ◽  
Giuseppe Padricelli ◽  
Giuseppe Marzo
Keyword(s):  
Motion Tracking ◽  
Dynamic Testing ◽  
Three Dimensional ◽  
Cephalometric Analysis ◽  
Facial Analysis ◽  
The Face ◽  
The Mean ◽  
2D And 3D ◽  
Very High ◽  
Posterior Anterior

Aim. This study aimed to evaluate the reliability of 3D-TMT, previously used only for dynamic testing, in a static cephalometric evaluation. Material and Method. A group of 40 patients (20 males and 20 females; mean age 14.2±1.2 years; 12–18 years old) was included in the study. The measurements obtained by the 3D-TMT cephalometric analysis with a conventional frontal cephalometric analysis were compared for each subject. Nine passive markers reflectors were positioned on the face skin for the detection of the profile of the patient. Through the acquisition of these points, corresponding plans for three-dimensional posterior-anterior cephalometric analysis were found. Results. The cephalometric results carried out with 3D-TMT and with traditional posterior-anterior cephalometric analysis showed the 3D-TMT system values are slightly higher than the values measured on radiographs but statistically significant; nevertheless their correlation is very high. Conclusion. The recorded values obtained using the 3D-TMT analysis were correlated to cephalometric analysis, with small but statistically significant differences. The Dahlberg errors resulted to be always lower than the mean difference between the 2D and 3D measurements. A clinician should use, during the clinical monitoring of a patient, always the same method, to avoid comparing different millimeter magnitudes.

Sand bars in tidal channels. Part 1. Free bars

2001 ◽  
Vol 440 ◽  
pp. 49-74 ◽  
Author(s):  
G. SEMINARA ◽  
M. TUBINO
Keyword(s):  
Three Dimensional ◽  
Basic Mechanism ◽  
Critical Value ◽  
Suspended Load ◽  
Tidal Channels ◽  
Three Dimensional Model ◽  
Mean Values ◽  
Depth Ratio ◽  
Mean Width ◽  
The Mean

We investigate the basic mechanism whereby bars form in tidal channels or estuaries. The channel is assumed to be long enough to allow neglect of the effects of end conditions on the process of bar formation. In this respect, the object of the present analysis differs from that of Schuttelaars & de Swart (1999) who considered bars of length scaling with the finite length of the tidal channel. The channel bottom is assumed to be cohesionless and consisting of uniform sediments. Bars are shown to arise from a mechanism of instability of the erodible bed subject to the propagation of a tidal wave. Sediment is assumed to be transported both as bedload and as suspended load. A fully three-dimensional model is employed both for the hydrodynamics and for sediment transport. At the leading order of approximation considered, the effects of channel convergence, local inertia and Coriolis forces on bar instability are shown to be negligible. Unlike fluvial free bars, in the absence of mean currents tidal free bars are found to be non-migrating features (in the mean). Instability arises for large enough values of the mean width to depth ratio of the channel, for given mean values of the Shields parameter and of the relative channel roughness. The role of suspended load is such as to stabilize bars in the large-wavenumber range and destabilize them for small wavenumbers. Hence, for large values of the mean Shields stress, it turns out that the first critical mode (the alternate bar mode) is characterized by a very small value of the critical width to depth ratio. Furthermore, the order-m mode being characterized by a critical value of the width to depth ratio equal to m times the critical value for the first mode, it follows that for large values of the mean Shields stress several unstable modes are simultaneously excited for relatively low values of the aspect ratio. This suggests that the actual bar pattern observed in nature may arise from an interesting nonlinear competition among different unstable modes.

scholarly journals Three-dimensional Alignment of the Upper Extremity in the Standing Neutral Position in Healthy Subjects

2022 ◽  
Author(s):  
Yuki Yoshida ◽  
Noboru Matsumura ◽  
Yoshitake Yamada ◽  
Satoshi Hiraga ◽  
Kazunori Ishii ◽  
...  
Keyword(s):  
Upper Extremity ◽  
Internal Rotation ◽  
Glenohumeral Joint ◽  
Three Dimensional ◽  
Upper Extremities ◽  
Neutral Position ◽  
Functional Evaluation ◽  
Ct Scanner ◽  
Angular Rotation ◽  
The Mean

Abstract Background: Though alignment of the spine and lower extremities in the standing neutral position has been evaluated, a few studies evaluating the alignment of the upper extremities have also been made. This study assessed the normal alignment of the upper extremities in the standing neutral position and clarified the three-dimensional angular rotations of the upper extremity joints.Methods: Computed tomography (CT) images of 158 upper extremities from 79 healthy volunteers were prospectively acquired in the standing neutral position using an upright CT scanner. Three-dimensional coordinate systems of the thorax, scapula, humerus, and forearm were designated, and three-dimensional angular rotations of the scapulothoracic, glenohumeral, and elbow joints were calculated.Results: The mean angle of the scapulothoracic joint was 8.5° ± 5.9° of upward rotation, 28.7° ± 5.9° of internal rotation, and 7.9° ± 5.2° of anterior inclination. The mean angle of the glenohumeral joint was 4.4° ± 5.9° of abduction, 9.4° ± 12.3° of internal rotation, and 0.3° ± 4.4° of extension. The mean angle of the elbow joint was 9.6° ± 3.7° of valgus, 88.8° ± 14.3° of pronation, and 15.4° ± 4.2° of flexion. Correlations in angular rotation values were found, and interactions for keeping the upper extremities in a neutral position were observed.Conclusions: This study clarified the three-dimensional angular rotation of upper extremity joints in the standing neutral position using an upright CT scanner. Our results may provide important insights for the functional evaluation of upper extremity alignment.

scholarly journals Radiosity Approach for the Shortwave Surface Radiation Balance in Complex Terrain

2009 ◽  
Vol 66 (9) ◽  
pp. 2900-2912 ◽  
Author(s):  
Nora Helbig ◽  
Henning Löwe ◽  
Michael Lehning
Keyword(s):  
Complex Terrain ◽  
Gaussian Approximation ◽  
Three Dimensional ◽  
Gaussian Random Fields ◽  
Surface Radiation ◽  
Radiation Balance ◽  
Length Scales ◽  
Mean Values ◽  
Terrain Effects ◽  
The Mean

Abstract The influence of topography on the radiation balance in complex terrain has so far been investigated either with very simple or very sophisticated approaches that are limited, respectively, by an uncontrolled spatial representation of radiative fluxes or heavy computational efforts. To bridge this gap in complexity, this paper proposes the radiosity approach, well known in computer graphics, to study anisotropic reflections of radiation in complex terrain. To this end the radiosity equation is rederived in the context of three-dimensional radiative transfer. The discretized equation is solved by means of an adapted version of progressive refinement iteration. To systematically study terrain effects, the geometrical disorder provided by the topography is considered in its simplest approximation by Gaussian random fields. These model topographies capture the most important length scales of complex terrain, namely a typical elevation and a typical valley width via the variance and the correlation length of the field, respectively. The mean reflected radiation is computed as a function of these length scales and sun elevation, thereby explicitly addressing finite system sizes and grid resolutions. A comparison with an isotropic parameterization of terrain reflections reveals that mean values are similar whereas spatial distributions vary remarkably. It is also shown that the mean reflected radiation in real topography is reasonably well characterized by the Gaussian approximation. As a final application of the method, the effective albedo of a topography is shown to vary with sun elevation and domain-averaged albedo, leading to albedo differences up to 0.025.

REDUCED TRANSFER MATRIX APPROACH FOR ISING MODEL

2011 ◽  
Vol 25 (21) ◽  
pp. 2895-2903 ◽  
Author(s):  
TUNCER KAYA ◽  
MURAT ARIK
Keyword(s):  
Transfer Matrix ◽  
Coupling Strength ◽  
Spontaneous Magnetization ◽  
Mean Field Theory ◽  
Mean Field ◽  
Three Dimensional ◽  
Critical Coupling ◽  
Transfer Matrix Approach ◽  
The Mean ◽  
2D And 3D

In this work, we present a simple approximate transfer matrix method for 2D and 3D Ising ferromagnet to calculate spontaneous magnetization of the system. The critical coupling strength Kc of 2D and 3D Ising models in reduced transfer matrix approximation is obtained quite accurately by simple improvements over the mean field theory. The important physical effect we include is the some of the fluctuations effects of the systems directly with help of this method. We predict from the spontaneous magnetization curve that the critical coupling strength Kc=J/kBT = 0.401 and 0.245 for two-dimensional (2D) and three-dimensional (3D) systems, respectively.

scholarly journals Is the Walch B3 glenoid significantly worse than the B2?

2017 ◽  
Vol 10 (4) ◽  
pp. 256-261 ◽  
Author(s):  
Kevin Chan ◽  
Nikolas K. Knowles ◽  
Jean Chaoui ◽  
Louis M. Ferreira ◽  
Gilles Walch ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Humeral Head ◽  
Three Dimensional ◽  
Computed Tomography Scans ◽  
The Mean ◽  
Scapular Plane ◽  
Glenoid Plane

Background The Walch B3 glenoid is theorized to be a progression of the B2 biconcave pattern. The present study aimed to compare glenoid indices between B2 and B3 patterns. We hypothesized that the B3 pattern would have significantly worse retroversion, inclination and medialization. Methods Computed tomography scans of 50 patients with B2 erosions [mean (SD) age 68 (9) years; 25 male] and 50 patients with B3 erosions [mean (SD) age 72 (8) years; 22 males] were converted into three-dimensional reconstructions. Retroversion, inclination, medialization and humeral head subluxation were compared. Results The data demonstrated no statistically significant differences [mean (SD)] between groups when assessing retroversion: B2 = 21 (8)°, B3 = 24 (7)° ( p = 0.602); glenoid inclination: B2 = 9 (6)°, B3 = 8 (6)° ( p = 0.967); or medialization: B2 = 12 (4) mm, B3 = 14 (4) mm ( p = 0.384). In the B2 group, the mean (SD) humeral head subluxation was 80% (10%) according to the scapular plane and 55% (9%) according to the glenoid plane, which was not statistically different from the B3 group with a mean (SD) humeral head subluxation of 81% (7%) according to the scapular plane ( p = 0.680) and 54% (7%) according to the glenoid plane ( p = 0.292). Conclusions These results demonstrated no significant differences between the B2 and B3 erosion patterns, with respect to the glenoid indicies measured. The aetiology of the B3 glenoid cannot be completely explained by progression of wear in a B2 glenoid.

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