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PubMed1999

Wall motion abnormalities in male elite orienteers are aggravated by exercise.

During the period 1979-92, 16 (15 men and one woman) sudden unexpected cardiac deaths occurred among young Swedish orienteers. This finding indicated a sharp increase in the death rate of orienteers, and necropsy demonstrated that myocarditis was a common histopathological finding. Therefore, an extensive non-invasive cardiac investigation was performed. A total of 59 male élite orienteers (mean age 23 years) and 36 cross-country skiers and middle-distance runners (mean age 22 years), serving as controls, were examined by both echocardiography at rest and radionuclide ventriculography at rest and during exercise. Wall motion abnormalities were found in eight orienteers using echocardiography. The purpose of this study was to examine whether the group of orienteers with wall motion abnormalities found using echocardiography had a smaller increase in ejection fraction from rest to exercise using radionuclide ventriculography than the rest of the orienteers and the controls, indicating an aggravation of the wall motion abnormalities during exercise. There were no significant differences in the ejection fraction at rest between the groups. In the orienteers with wall motion abnormalities (group 1), 62% (five out of eight) had less than a 0.05 unit increase in left ventricular ejection fraction compared with 27% (14 out of 51) of the remaining orienteers (group 2) and 19% (7 out of 36) of the controls (group 3). A comparison of athletes in group 1 with those in groups 2 and 3 combined revealed a statistically significant difference (P < 0.05). The divergent response in left ventricular ejection fraction during exercise suggests an aggravation of the wall motion abnormalities with exercise. Both the echocardiographic and the radionuclide ventriculographic findings indicate that the orienteers in group 1 had concealed left ventricular damage.

Adolescent↗
PubMed2004

In search of temporal power laws in the orientational relaxation near isotropic-nematic phase transition in model nematogens.

Recent Kerr relaxation experiments by Gottke et al. have revealed the existence of a pronounced temporal power law decay in the orientational relaxation near the isotropic-nematic phase transition (INPT) of nematogens of rather small aspect ratio, kappa (kappa approximately 3-4). We have carried out very long (50 ns) molecular dynamics simulations of model (Gay-Berne) prolate ellipsoids with aspect ratio 3 in order to investigate the origin of this power law. The model chosen is known to undergo an isotropic to nematic phase transition for a range of density and temperature. The distance dependence of the calculated angular pair correlation function correctly shows the emergence of a long range correlation as the INPT is approached along the density axis. In the vicinity of INPT, the single particle second rank orientational time correlation function exhibits power law decay, (t(-alpha)) with exponent alpha approximately 2/3. More importantly, we find the sudden appearance of a pronounced power-law decay in the collective part of the second rank orientational time correlation function at short times when the density is very close to the transition density. The power law has an exponent close to unity, that is, the correlation function decays almost linearly with time. At long times, the decay is exponential-like, as predicted by Landau-de Gennes mean field theory. Since Kerr relaxation experiments measure the time derivative of the collective second rank orientational pair correlation function, the simulations recover the near independence of the signal on time observed in experiments. In order to capture the microscopic essence of the dynamics of pseudonematic domains inside the isotropic phase, we introduce and calculate a dynamic orientational pair correlation function (DOPCF) obtained from the coefficients in the expansion of the distinct part of orientational van Hove time correlation function in terms of spherical harmonics. The DOPCF exhibits power law relaxation when the pair separation length is below certain critical length. The orientational relaxation of a local director, defined in terms of the sum of unit vectors of all the ellipsoidal molecules, is also found to show slow power law relaxation over a long time scale. These results have been interpreted in terms of a newly developed mode coupling theory of orientational dynamics near the INPT. In the present case, the difference between the single particle and the collective orientational relaxation is huge which can be explained by the frequency dependence of the memory kernel, calculated from the mode coupling theory. The relationship of this power law with the one observed in a supercooled liquid near its glass transition temperature is explored.

Journal Article↗
PubMed2006

Goal orientations and moral identity as predictors of prosocial and antisocial functioning in male association football players.

The purpose of this study was to examine the effects of task and ego goal orientation and moral identity on prosocial and antisocial judgement and behaviour in football. The interaction between task and ego orientation in predicting these variables was also examined. Participants were 210 adult male footballers (age 25 +/- 6 years) competing at recreational (n = 133) and semi-professional (n = 77) levels. They completed questionnaires measuring task and ego goal orientation, the importance of moral identity, prosocial and antisocial judgement, frequency of prosocial and antisocial behaviours in football, and social desirability. Regression analysis revealed no main effects for goal orientations and moral identity on prosocial judgement and behaviour. However, a significant interaction effect between task and ego orientation emerged in relation to prosocial judgement. Specifically, task orientation positively predicted prosocial judgement only at low levels of ego orientation. Ego orientation emerged as a positive predictor of antisocial judgement and behaviour, whereas moral identity negatively predicted these variables. The differentiation between prosocial and antisocial aspects of morality was supported. It was concluded that examining moral identity and interactions between task and ego orientation adds to our understanding of the influence of these variables on prosocial and antisocial functioning in sport.

Adult↗
PubMed2005

Adolescents' health-related behaviors in the light of their value orientations.

This study examines the relationship between adolescents' health behaviors and their value orientations. Data were collected among a sample of Hungarian urban high school students (n = 602, aged 14-19; 52.8% males and 47.2% females) in 2001. Factor analysis revealed fitness-oriented, health and social value oriented, and accomplishment/career oriented value factors. Health and social values were more common among girls, while accomplishment-oriented values were more common among boys. The fitness-oriented value orientation was related to physical activity and diet control, health and social value orientation showed significant association with diet control and the lack of smoking, alcohol and drug use, accomplishment oriented values were related to higher levels of substance use.

Adolescent↗
PubMed1999

Constrained customization of non-coplanar beam orientations in radiotherapy of brain tumours.

A methodology for the constrained customization of non-coplanar beam orientations in radiotherapy treatment planning has been developed and tested on a cohort of five patients with tumours of the brain. The methodology employed a combination of single and multibeam cost functions to produce customized beam orientations. The single-beam cost function was used to reduce the search space for the multibeam cost function, which was minimized using a fast simulated annealing algorithm. The scheme aims to produce well-spaced, customized beam orientations for each patient that produce low dose to organs at risk (OARs). The customized plans were compared with standard plans containing the number and orientation of beams chosen by a human planner. The beam orientation constraint-customized plans employed the same number of treatment beams as the standard plan but with beam orientations chosen by the constrained-customization scheme. Improvements from beam orientation constraint-customization were studied in isolation by customizing the beam weights of both plans using a dose-based downhill simplex algorithm. The results show that beam orientation constraint-customization reduced the maximum dose to the orbits by an average of 18.8 (+/-3.8, ISD)% and to the optic nerves by 11.4 (+/-4.8, ISD)% with no degradation of the planning target volume (PTV) dose distribution. The mean doses, averaged over the patient cohort, were reduced by 4.2 (+/-1.1, ISD)% and 12.4 (+/-3.1, ISD)% for the orbits and optic nerves respectively. In conclusion, the beam orientation constraint-customization can reduce the dose to OARs, for few-beam treatment plans, when compared with standard treatment plans developed by a human planner.

Adenoma↗
PubMed2001

Computer-assisted selection of coplanar beam orientations in intensity-modulated radiation therapy.

In intensity-modulated radiation therapy (IMRT), the incident beam orientations are often determined by a trial and error search. The conventional beam's-eye view (BEV) tool becomes less helpful in IMRT because it is frequently required that beams go through organs at risk (OARs) in order to achieve a compromise between the dosimetric objectives of the planning target volume (PTV) and the OARs. In this paper, we report a beam's-eye view dosimetrics (BEVD) technique to assist in the selection of beam orientations in IMRT. In our method, each beam portal is divided into a grid of beamlets. A score function is introduced to measure the 'goodness' of each beamlet at a given gantry angle. The score is determined by the maximum PTV dose deliverable by the beamlet without exceeding the tolerance doses of the OARs and normal tissue located in the path of the beamlet. The overall score of the gantry angle is given by a sum of the scores of all beamlets. For a given patient. the score function is evaluated for each possible beam orientation. The directions with the highest scores are then selected as the candidates for beam placement. This procedure is similar to the BEV approach used in conventional radiation therapy, except that the evaluation by a human is replaced by a score function to take into account the intensity modulation. This technique allows one to select beam orientations without the excessive computing overhead of computer optimization of beam orientation. It also provides useful insight into the problem of selection of beam orientation and is especially valuable for complicated cases where the PTV is surrounded by several sensitive structures and where it is difficult to select a set of 'good' beam orientations. Several two-dimensional (2D) model cases were used to test the proposed technique. The plans obtained using the BEVD-selected beam orientations were compared with the plans obtained using equiangular spaced beams. For all the model cases investigated, the use of BEVD-selected beam orientations improved the dose distributions significantly. These examples indicate that the technique has considerable potential for simplifying the IMRT treatment planning process and allows for better utilization of the technical capacity of IMRT.

Humans↗
PubMed1997

Relationships between the orientation and moment arms of the human jaw muscles and normal craniofacial morphology.

It has been suggested that subjects with increased vertical craniofacial dimensions have relatively oblique orientated jaw muscles with a reduced possibility to restrain the vertical component of craniofacial growth. To test this hypothesis, relationships were investigated between the spatial orientation of the jaw muscles and the craniofacial morphology. Computer reconstructions of the external shape of the jaw muscles of 30 adult males with a normal skull were made with the use of serial magnetic resonance imaging (MRI) scans. The orientation of the jaw muscles was defined by a regression line through the centroids of the serial cross-sections. Sagittal and frontal projections of the moment arms of the muscles were measured with respect to the centre of the ipsilateral condyle. Craniofacial morphology was analysed three-dimensionally using lateral head films and coronal MRI scans. The cephalometric data were analysed statistically using regression and factor analyses. Six cephalometric factors with Eigen values higher than 1 were correlated with jaw muscle orientation and moment arm data, using a multiple regression analysis. The anterior face height factor was significantly correlated with the orientation of the jaw opening muscles in the sagittal plane but was not significantly correlated with the orientation of the mandibular elevators. The sagittal moment arms of the mandibular elevators showed significant correlations with the factors describing the gonial angle and the posterior face height. It was concluded that the variation of spatial orientation of the human jaw closing muscles is predominantly associated with the variation of mandibular morphology (expressed by the gonial angle) and the posterior face height. The orientation of the jaw opening muscles shows significant relationships with anterior vertical craniofacial dimensions. The hypothesis that persons with an increased anterior face height have relatively oblique orientated jaw elevators was rejected.

Adult↗
PubMed1989

What is the ideal orientation of a mitral disc prosthesis? An in vivo haemodynamic study based on colour flow imaging and continuous wave Doppler.

Doppler colour flow imaging demonstrates normal laminar flow to enter the left ventricle in diastole through the mitral inflow tract located posteriorly in the left ventricle. Laminar flow then passes around the left ventricular apex to the anteriorly located outflow tract. As this is the normal physiologic flow pattern, it would seem appropriate that in the surgical implantation of a mitral tilting disc prosthesis the greater orifice should be directed posteriorly to mimic the normal native valve flow pattern. To determine whether variable positioning of the greater orifice had any significant haemodynamic consequences, intracavitary blood flow patterns were studied in 30 patients with mitral Björk-Shiley prostheses variously orientated in the mitral orifice. The orientation of the greater orifice (OGO) of the prosthesis was determined by fluoroscopy and the pattern of the left ventricular inflow from Doppler colour flow imaging. Twelve patients had their OGO and inflow directed towards the inflow tract (orientation I): nine patients had their OGO and inflow directed anteriorly towards the outflow tract (orientation II) and nine patients had their prosthesis with OGO and inflow in an intermediate position (orientation III). The mean prosthetic diastolic gradient, calculated using continuous wave Doppler, averaged 2.8 mmHg (+/- 0.5 mmHg) for the 25-mm prosthesis in orientation I, but 6.0 mmHg (+/- 0.7 mmHg) for the same size prosthesis in orientation II and 5.8 mmHg (+/- 0.9 mmHg) with a 25-mm prosthesis in orientation III. Similarly, for prostheses of 27 mm and 29-31 mm the lowest mean diastolic gradient was found in orientation I (2.7 mmHg +/- 0.8 and 2.8 mmHg +/- 0.5, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Esophagitis: optimizing diagnostic yield by biopsy orientation.

OBJECTIVES: There is poor correlation between gastroesophageal reflux (GER) symptoms, intraesophageal pH monitoring and endoscopic or histologic appraisal of esophagitis in the pediatric age group. To optimize the diagnosis of childhood esophagitis, histologic evaluation of esophageal pinch and suction biopsies after orientation were compared. METHODS: Thirty consecutive children with GER, age range 6 months to 7 years, were prospectively evaluated with upper gastrointestinal endoscopy and biopsy. Three pinch biopsies and one suction biopsy were examined after different methods of biopsy orientation. The suction biopsy orientated with x 10 magnification represented the standard against which the pinch biopsies were compared. RESULTS: After suction biopsy with tissue orientation using x 10 magnification 90% of biopsies were adequate for histologic appraisal. Ninety-three percent of esophageal pinch biopsies orientated with x 10 magnification were adequate for analysis. After pinch biopsy orientated without magnification 90% of biopsies were suitable for histologic appraisal. Finally, in the pinch biopsy group without formal orientation, only 63% of the biopsies were adequate for histologic analysis and diagnosis of esophagitis. CONCLUSION: Orientation of esophageal pinch biopsies improves histologic appraisal and hence increases the diagnostic yield of esophagitis in children with GER. The tissue fragments can be easily orientated in the endoscopy room before placement in fixative.

Biopsy↗
PubMed2005

Influence of preload magnitudes and orientation angles on the cervical biomechanics: a finite element study.

OBJECTIVE: Although a number of in vivo, in vitro, and finite element studies have attempted to delineate the natural biomechanics, injury mechanisms, and surgical techniques of the cervical spine, none has explored the influence of various preload magnitudes and orientations on the biomechanical responses. METHODS: A nonlinear three-dimensional finite element model of the lower cervical spine (C5-C6) was used for this study. The model was tested under four preload magnitudes and three orientations. For every preload, magnitude, and orientation, pure moments of 1.8 Nm were applied to the superior surface of the moving vertebra (C5) in flexion, extension, lateral bending, and torsion. The resulting rotational motions were obtained and compared against literature data. RESULTS: The predicted biomechanical responses under the same loading directions varied, depending on the preload magnitudes and orientations. With flexion and extension, increasing the preload magnitudes and varying the C5-C6 orientation in the sagittal plane changed the rotational motions by 1% and 18%, respectively. Under normal orientation and with increasing preload magnitudes, flexion and extension increased, whereas lateral bending and torsion decreased. These changes were found to be influenced by several spinal components: posterior facets, passive ligaments, and stiffening of the intervertebral disc. The predicted responses under the direction of loading varied significantly, depending on the preload magnitudes and orientations. Under fixed preload magnitudes and varying the three types of orientations, rotational motions were not affected under flexion but changed under extension, lateral bending, and axial rotations. Under normal orientation and increasing preload magnitudes, biomechanical responses under flexion and extension increased, whereas lateral bending and torsion decreased. Changes in the predicted responses were found to be influenced by several spinal components: posterior facets, passive ligaments, and stiffening of the intervertebral disc. CONCLUSION: The findings of the current study were important for the further understanding of the cervical biomechanics during in vitro testing.

Biomechanical Phenomena↗
PubMed2002

Ordering and short-time orientational diffusion in dipolar hard-spherical colloids.

Orientational hydrodynamic functions and short-time, self-orientational and collective orientational diffusion coefficients of dipolar hard-spherical colloids are performed on a homogeneous isotropic phase, as functions of the wave vector q, for various values of the volume fraction and the dipolar strength of the macroparticles. The calculation is based on the dynamic orientational structure factor, which is the time-dependent self-correlation of the orientation density. We assume that the time evolution of the orientation density is given by the Smoluchoswki's equation, taking into account the hydrodynamic interactions as well as the dipolar interaction. The former are considered assuming pairwise additivity. The importance of the dynamic orientational structure factor is that its initial slope can be measured in a depolarized light scattering experiment. The results predict a different behavior for dilute and for dense dipolar colloids. The ordering phenomena are studied via the ordering coefficients, which are the orientational hydrodynamic functions at q=0. The results show that as the dipolar colloid evolves to the instability line, the translational ordering velocity increases while the rotational one reduces. The short-time orientational diffusion coefficients at q=0 are also performed. They predict that near to the instability line, the dipolar colloid diffuses translationally more than rotationally. At very dilute concentration the dipolar colloid presents an unexpected dynamical behavior, which seems to indicate that the colloid could be evolving to a reentrant phase.

Journal Article↗
PubMed2002

Alteration of oriented deposition of cellulose microfibrils by mutation of a katanin-like microtubule-severing protein.

It has long been hypothesized that cortical microtubules (MTs) control the orientation of cellulose microfibril deposition, but no mutants with alterations of MT orientation have been shown to affect this process. We have shown previously that in Arabidopsis, the fra2 mutation causes aberrant cortical MT orientation and reduced cell elongation, and the gene responsible for the fra2 mutation encodes a katanin-like protein. In this study, using field emission scanning electron microscopy, we found that the fra2 mutation altered the normal orientation of cellulose microfibrils in walls of expanding cells. Although cellulose microfibrils in walls of wild-type cells were oriented transversely along the elongation axis, cellulose microfibrils in walls of fra2 cells often formed bands and ran in different directions. The fra2 mutation also caused aberrant deposition of cellulose microfibrils in secondary walls of fiber cells. The aberrant orientation of cellulose microfibrils was shown to be correlated with disorganized cortical MTs in several cell types examined. In addition, the thickness of both primary and secondary cell walls was reduced significantly in the fra2 mutant. These results indicate that the katanin-like protein is essential for oriented cellulose microfibril deposition and normal cell wall biosynthesis. We further demonstrated that the Arabidopsis katanin-like protein possessed MT-severing activity in vitro; thus, it is an ortholog of animal katanin. We propose that the aberrant MT orientation caused by the mutation of katanin results in the distorted deposition of cellulose microfibrils, which in turn leads to a defect in cell elongation. These findings strongly support the hypothesis that cortical MTs regulate the oriented deposition of cellulose microfibrils that determines the direction of cell elongation.

Adenosine Triphosphatases↗
PubMed2006

On the orientability of shapes.

The orientation of a shape is a useful quantity, and has been shown to affect performance of object recognition in the human visual system. Shape orientation has also been used in computer vision to provide a properly oriented frame of reference, which can aid recognition. However, for certain shapes, the standard moment-based method of orientation estimation fails. We introduce as a new shape feature shape orientability, which defines the degree to which a shape has distinct (but not necessarily unique) orientation. A new method is described for measuring shape orientability, and has several desirable properties. In particular, unlike the standard moment-based measure of elongation, it is able to differentiate between the varying levels of orientability of n-fold rotationally symmetric shapes. Moreover, the new orientability measure is simple and efficient to compute (for an n-gon we describe an O(n) algorithm).

Algorithms↗
PubMed1995

The empirical relationships of the religious orientations to personality.

The aim of this study was to investigate the relationships between the religious orientations and the psychoanalytic character types, as assessed by the Basic Character Inventory (BCI). A person with an intrinsic religious orientation is sincere and integrated in his religiousness. A person with an extrinsic religious orientation uses his religion to promote his personal, social and economic goals. A person with a quest religious orientation is seeking, doubting and changeable in his religiousness. In a sample of 471 subjects, 168 men and 303 women, the level of intrinsic religious orientation was not related to the BCI scores. The levels of extrinsic and quest religious orientations were positively related to the BCI Oral score. Since the oral persons are dependent and craving, it seems likely that they may be extrinsically oriented. And as they also may be insecure, vague and indecisive, it is not unexpected that they also are quest oriented. The changeable quest orientation was also positively related to the changeable BCI Hysterical character.

Adolescent↗
PubMed2005

Determination of left ventricular long-axis orientation using MRI: changes during the respiratory and cardiac cycles in normal and diseased subjects.

BACKGROUND: It has previously been shown that magnetic resonance imaging (MRI) can be used to accurately determine left ventricular (LV) long-axis orientation in healthy individuals. However, the inter- and intra-observer variability in patients with acute coronary syndrome (ACS) and chronic heart failure (CHF) has not been explored. Furthermore, the changes in LV long-axis orientation because of respiration and during the cardiac cycle remain to be determined. METHODS: LV long-axis orientation was determined by MRI in the frontal and transverse planes in 44 subjects with no cardiac disease, 20 ACS patients and 13 CHF patients. Changes in LV long-axis orientation because of respiration were assessed in a subset of 25 subjects. Changes during the cardiac cycle were assessed in six subjects from each subject group. Reproducibility was assessed by a re-examination of 17 subjects after 28 days. RESULTS: The inter- and intra-observer variability for LV long-axis orientation was low for all subject groups. The difference between the baseline and the 28 days examinations was -1.4+/-5.9 degrees and -0.8+/-4.4 degrees in the frontal and transverse planes, respectively. No significant change in LV long-axis orientation was found between end-expiration and end-inspiration (frontal plane, P=0.63 and transverse plane, P=0.42; n=25). No significant difference in change of the LV long-axis orientation during the cardiac cycle was found between the subject groups (frontal plane, chi-square 1.8, P=0.40 and transverse plane, chi-square 5.7, P=0.06). CONCLUSIONS: There is a low inter-and intra-observer variability and a high reproducibility for determining LV long-axis orientation in patients with no cardiac disease as well as in patients with ACS or CHF. There is no significant change in LV long-axis orientation due to respiration, and only small changes during the cardiac cycle in these groups.

Adult↗
PubMed2001

Histomorphometric and mechanical evaluation of the bone-tissue response to implants prepared with different orientation of surface topography.

BACKGROUND: Several studies have shown that in soft tissue, the orientation of surface topography affects cell response. However, the response of hard tissue to the orientation is not fully understood. PURPOSE: This study was undertaken to determine how orientation of the microstructure of implant surfaces influences bone healing. MATERIALS AND METHODS: Forty cylindrical implants were prepared with a dominant orientation of the microstructure (20 with a horizontal orientation and 20 with a vertical orientation) and investigated in vivo. Three methods for surface topographic characterization were used to investigate the topography in different resolution levels. RESULTS: Topographic analysis showed that a clear orientation was achieved at the implant surface, and a rougher surface structure was found on the vertically oriented grooves than on the horizontal ones. The implants were inserted in the tibia of 10 New Zealand White rabbits. Pull-out tests and histomorphometric analyses of ground-sections were made after 12 weeks of healing. The pull-out test showed a higher mean value for the vertically grooved implants, but the difference was not significant. Histomorphometric analyses showed no statistically significant differences between the horizontally and the vertically grooved implants when measuring bone-to-implant contact or amount of bone area around the implant. CONCLUSIONS: No advantages could be found for either the horizontal or vertical orientation compared with each other, but further studies are needed in which implant roughness should be similar between the different topographies.

Animals↗
PubMed1997

Quantitative characterization of vascular endothelial cell morphology and orientation using Fourier transform analysis.

Fourier Transform methods were used to quantify mean elongation, mean orientation, and standard deviation of orientations of cultured vascular endothelial cells. Images of cell populations, which had been subjected to 11 and 20 hours of shear stress at 30 dynes/cm2 and 20 hours of no shear, were analyzed by Fourier Transform methods. Measurements of cell morphology and orientation characteristics were also obtained using a manual method for comparison purposes. The results of the study showed that mean cell orientation can be determined accurately with the Fourier Transform methods. Attempts to determine the standard deviation of cell orientations, however, resulted in poorer estimates of mean elongation and standard deviation of orientations except in the case of exposure of endothelial cells to 20 hours of shear, where the actual standard deviation of orientations was low. When the value for standard deviation of orientations was constrained to zero, a minimum possible mean elongation was determined reliably using the Fourier Transform methods. Use of the Fourier Transform methods in determining morphological and orientation characteristics of cell monolayers is fast and objective and may provide a basis for identifying other characteristics of cell shape.

Animals↗
PubMed2003

Topology-based orientation analysis of trabecular bone networks.

After bone mineral density, orientation is the major determinant of trabecular bone strength and is thus of significant interest in understanding the clinical implications of osteoporotic bone loss. The methods used to measure orientation and anisotropy of the trabecular bone have largely relied on deriving global measures along test lines, computing the best-fit ellipsoid, and decomposing to eigenvalue-eigenvector pairs that yield the mean orientation and anisotropy of the region. These techniques ignore the differences between measuring the orientation of trabecular plates versus rods, and do not provide insight into the relationship between local orientation and biomechanical stresses. Digital topological analysis allows a unique determination of each voxel's topological class as belonging to a plate, rod, or junction. The digital topology-based orientation analysis (DTA-O) method extracts the voxels belonging to plates and determines the local surface normal by fitting a plane through the local neighborhood BVF map. Modeling regional distributions of these vectors allows assessment of anisotropy measures, such as mean and variance of the orientation distribution. High-resolution microcomputed tomography, synthetic, and in vivo images were used for a validation of the new method and compare the results with the mean intercept length (MIL) technique. The results indicate that DTA-O is a better measure of trabecular orientation and anisotropy than MIL. Applying DTA-O to a recently completed study on the distal radius of 82 subjects [F.W. Wehrli et al., J. Bone Min. Res. 16, 1520 (2001)] shows that the mean orientation and anisotropy at the medial and lateral sides in the distal radius mataphyseal trabecular network are consistent with the mechanical stresses acting on the radius during common tasks.

Adult↗