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V Royant

Publications and source records attributed to V Royant.

5 recordsLinked to original sources
PubMed1998

Fractal analysis of trabecular bone texture on radiographs: discriminant value in postmenopausal osteoporosis.

Trabecular bone microarchitecture cannot be routinely evaluated. We have developed and validated a fractal analysis of trabecular bone texture on calcaneus radiographs. The aim of this work was to evaluate the ability of the fractal analysis to discriminate a group of 39 postmenopausal women with osteoporotic (OP) vertebral crush fractures (68.0 +/- 10.8 years) from an age-matched control group of 39 women (68.0 +/- 10.7 years). The value of the fractal analysis was compared with the value of the femoral neck bone mineral density (FNBMD) and trochanteric bone mineral density (TRBMD). The result is expressed by the parameter Hmean (Hmean = 2 - fractal dimension). Hmean value was 0.691 +/- 0.050 in the OP group versus 0.739 +/- 0.024 in the controls, while FNBMD was 0.598 +/- 0.113 g/cm2 versus 0.645 +/- 0.109 g/cm2 and TRBMD was 0.512 +/- 0.108 g/cm2 versus 0.594 +/- 0.106 g/cm2 respectively. The statistical significance of the Hmean test (p < 0.0001) was higher than for FNBMD (p < 0.05) and for TRBMD (p = 0.0004). We used a receiver operating characteristic (ROC) curve to check this superiority. The area under the ROC curve was 0.824 for Hmean, 0.633 for FNBMD and 0.727 for TRBMD. This superiority of the Hmean ROC curve was statistically significant versus FNBMD, but not versus TRBMD. In a second analysis, we studied the subgroups of OP patients and controls with overlapping FNBMD or TRBMD values to check whether the fractal dimension test could be discriminant in these subgroups. Significant statistical differences were found for Hmean between OP patients and controls in the overlapping subgroup for FNBMD or TRBMD (respectively p = 0.006 and p < 0.02). These data confirm that the fractal analysis of texture on calcaneus radiographs is able to discriminate OP patients with vertebral crush fracture from controls. This discrimination was stronger than that obtained by FNBMD or TRBMD alone. It was also present when we compared subgroups with overlapping values of FNBMD or TRBMD.

Absorptiometry, Photon↗
PubMed1996

[Bone structure and mechanical resistance of the bone tissue].

The strength of bone depends on bone structure, both in terms of global geometry of the bone and the microscopic pattern of the trabecular network. Modifications in the trabecular organization, often related to the aging process, include altered anisotropy, perforations, loss of connectivity and microfractures. The microscopic architecture of trabecular bone can be studied on histomorphometric slices, the use of stereologic techniques on these slices may better reflect the changes occurring in 3 dimensions. High-resolution tomodensitometry and 3-D magnetic resonance imaging are under further evaluation. An evaluation of the fractal geometry of the trabecular network, performed on the vertebrae, calcaneus, or ulna on standard radiographs has given promising results. Bone strength is determined by resistance tests on bone tissue samples. The relationship between the applied force and bone deformation is used to determine a stress-strain curve and resistance parameters. The mechanical behavior of a given bone can be modelized by a Finite Element Analysis, the computerized model being able to predict the reaction of this bone. Ultra-sound analysis does not directly measure bone density, nor bone architecture, but would reflect both these properties. Velocity and attenuation of ultra-sounds, measured at the calcaneus or patella, are useful in distinguishing between controls and osteoporosis cases, and may have predictive value.

Adult↗
PubMed1996

Assessment of joint space width in patients with osteoarthritis of the knee: a comparison of 4 measuring instruments.

OBJECTIVE: To evaluate the intra and interobserver reproducibility of 4 measuring instruments for assessing joint space width in knee osteoarthritis (OA) and to estimate the effects of patients, instrument, session order, and reader variation. METHODS: We studied 30 patients with unilateral tibiofemoral OA selected to represent a broad range of radiographic changes. Joint space width (JSW) was measured on plain anteroposterior weight bearing radiographs. Using an experimental design, 3 readers assessed JSW 3 times with 4 measuring instruments (ruler, caliper, graduated magnifying glass, digitized assessment). RESULTS: Intra and interobserver reproducibility was high with all measuring instruments (intraclass correlation coefficients from 0.95 to 0.98 and from 0.91 to 0.97, respectively). Analysis of variance (ANOVA) showed a patient effect (p < 10(-6)), a reader effect (p = 0.0001), an instrument effect (p = 0.0001), and a session order effect (p = 0.04). The variance component estimates were patients 55%, readers 34%, session order 2%, instruments 8%. ANOVA performed separately for each instrument showed that session order differences always represented less than 1% of the total variance. The reader component accounted for 0% of the total variance for the ruler, 2% for the digitized method, 16% for the caliper, and 18% for the graduated magnifying glass. CONCLUSION: Ruler and digitized assessment have better reliability than caliper and graduated magnifying glass.

Analysis of Variance↗