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Development of a neural network-based computer aided diagnosis system for a vertebral morphometry workstation
Bone Vol. 19, No. 3, Supplement
September
1996: 129% 169s
The 7th International
Congress
Abstracts of Bone Morphometry
119
121
BONE MINERAL DENSITY COMPARES AND CONTRASTS WITH THE BIOMECHANICAL MEASUREMENTS OF CANINE BONE. D. Pienkowski, J. McCarter. T. Doers, R. Maitra, M.-C. MonierFaugere,’ H.H. Malluche’ Divisions of Orthopaedic Surgery and ‘Nephrology, Bone and Mineral Metabolism, University of Kentucky, Lexington, KY, (USA).
DEVELOPMENT OF A NEURAL NETWORK-BASED COMPUTER AIDED DIAGNOSIS SYSTEM FOR A VERTEBRAL MORPHOMETRY WORKSTATION J.Redei, P.J. Countryman, H.K. Genant Osteoporosis Research Group, Univ. of California, San Francisco (USA)
Dual energy X-ray Absorptiometry measurements of Bone Mineral Density (BMD) are reproducible, precise, and some reports indicate that they are related to fracture rates in bone, however, measurement of material quantity (i.e., density) alone may not be a complete measure of bone’s mechanical competence. The objective of this study was to quantitatively compare the ability of BMD measurements to predict the mechanical properties of bone. Both tibiae, both femurs, and 3 vertebrae (Ll, L3, L5) from 254 retired female breeder beagle dogs were excised. BMDs of long bones were measured in 3 planes, and BMDs of vertebrae were measured in 2 planes. Long bones were potted and torqued to failure. Ll and L5 vertebrae were compressed to failure. Cancellous cores were obtained from L3 bones and these cores were compressed to failure. Maximum load, stiffness, and energy to failure were measured in both the torsional and compressive tests. BMD of the long bones was poorly correlated (r = 0.1, typically) with their torsional biomechanical properties. In contrast, the BMD of the vertebrae (both whole and cancellous cores) were well correlated (r = 0.6-0.6, typically, p < 0.001) with their compressive biomechanical properties. BMD could not predict the torsional biomechanical properties of long bones because these properties depend not only upon how much material is present (which BMD can measure) but upon the geometric distribution of this material in the bone (which BMD cannot measure). Since the compressive biomechanical properties of bone are virtually independent of the geometry of materials location, this explains the ability of BMD to predict these compressive mechanical properties. BMD is useful for predicting the mechanical competence of bones loaded in compression, but is insufficient to predict the mechanical competence of bones loaded in torsion.
159s
We have implemented a digital image workstation for semiquantitative and quantitative (6-point morphometry) Vertebral Fracture Assessment (VFA) on conventional radiographs, for large multicenter osteoporosis drug trials’. In this context. we are developing an Artificial Neural Network (ANN) approach for VFA using landmark (Bpoint) data derived from lateral spine radiographs. Previous studies* indicated that an ANN using vertebral height measurements may improve conventional morphometric VFA. However, the use of interlandmark distances (multivariate morphometrics) might not take full advantage of the information represented in the landmark configurations. We are investigating methods to further optimize the performance of the ANN. 400 postmenopausal osteopenic women ware evaluated. Several combinations of morphometric features previously explored by others (anterior, mid and posterior vertebral heights, mean vertebral depth, intervertebral disc area) and also xy-coordinates from T4 to L4 (converted by a rotation- and translation-invariant transform) were fed into the input layer. The ANN was trained on 314 of the sample according to a ‘gold standard (joint semiquant. reading by 4 expert radioloaists). and tested on the remaining l/4. This process tias repeated for the>ther 4 quarters of the set. The ‘best” coordinate-based ANN achieved overall sensitivities and specificities comparable to those of the height-based ANN; e.g. at decision threshold 0.4 for ‘fracture’, sens=652/699=72.5%; spec=4027/4272=94.3%. However, correlation between network outouts of both ANN was only moderate (r=0.66. y=O.66x+O.O2, n=51’71). Combination of both recoanizers achieved sens=61.6% and soec=94.4%. A new useful methodhas been developed which 1) takesinto accotmt the highly intercorrelated vertebral dimensions in an individual’s spinal column, 2) allows the presence of partially missing input data, and 3) provides a means for compensating for changing fracture prevalence. A method of using coordinates for detecting vertebral shape has been introduced. 1. RddeiJ. et al. In: Genant HK (ed). Vertebral fracture in osteoporosis: 293-306,1995 2. RCdeiJ, Jergas M, Li J, Ouyang X. Genant HK. J. Bone Miner. Res. 10 (SuppI1): s370
120
122
BONE REMODELING AND PLASMA BONE MARKERS IN PIGS FED CALCIUM DEFICIENT DIETS. A Pointrllart E. Eklou, C. Calm and E. Zerath. LNSA INRA. Jouy en Josas (France) and IMASSA, Bretrgny I Orge (France)
HISTOMORPHOMETRIC QUANTIFICATION OF OSTEOCYTE LACUNO-CANALICUAR CAVITIES IN VARIOUS TYPES OF BONE TISSUE IN DIFFERENT ANIMAL SPECIES. F. Remaaai, C. Palumbo, M. Ferretti, V. Cane Dipattimento di Scienze Motfologiche e Medico Legali Sezione di Anatomia Umana, Universita di Modena (Italy)
Calcrum IS one of the most Important nongenetic factors that influence peak bone mass Almost all rn viva changes rn bone formatron caused by calcium deficrency have been demonstrated in rats [l]. which is probably not the best model of human nutrition We have therefore carried out a bone hrstomorphometric study in pigs fed Cadeficient diets. Three groups of 6 pigs (9.5 f 0 4 kg body weight) were fed diets containing 0 1 (Very Low Ca. VLCa). 0 4 (Low Ca) or 1% Ca (Controls) for 32 days. Bone remodeling was analyzed by histomorphometry on distal metacarpal metaphyses and blood samples were collected at slaughter to monitor the parameters of bone metabolism: Ca. alkalme phosphatase activity (ALP), calcrtrlol (1,25D). PTH, osteocalcin (BGP) and the C-terminal propeptide of type I collagen (PICP). ALP2 l,25D3 PTH3 BGP’ PlCP5 Plasma Cal Control 9 9” Boa 97” 13= 202a 2 98 LowCa 9.7a 72= 26@ 23b 314f’ 3a 1216 517c 49= 332b 3.36 VLCa 6b I mgllOOml, 2 rull, 3 pglml. 4 nglml. 5 mg/l atb*c ~~0.05 or p
A comparative histomorphometric study was carried out on the extension of the osteocytic lacuna-canalicular network between various types of bone tissue in shaft bones of animal of different species (Frog, Chicken, Rabbit, Bovine, Horse, Dog, Man). In woven-fibered interstitial bone, and in parallel-fibered and lamellar Haversian systems the following parameters were measured, by an Image Analyzer on undecalcified sections viewed under transmitted ordinary light, reflected polarized light, and on scanning electron micrographs: a) volume of osteocyte lacunae; b) density of osteocyte lacunae and canaliculi; c) number per unit length of canaliculi in the wall of Haversian systems, in relation to the distance from the center of their canals; d) number of canaliculi departing from the opposite walls of lacunae. In all animal species, histomorphometric data show that: a) size and density of osteocyte lacunae as well as canalicular density are significantly higher in woven-fibered than in parallel-fibered and lamellar bone; b) in Haversian systems, the number of canaliculi departing from the lacunar walls facing the vascular canal is significantly higher than from the opposite walls; however, the canalicular density does not significantly change at different concentric levels of the osteonal walls. When comparing the same type of bone tissue in animal of different species, no significant differences were recorded in the values of all the above mentioned parameters. Briefly it appears that osteocyte lacunar size and density as well as canalicular density depend on collagen texture rather than on animal species, i.e. phylogenic evolution. Since collagen spatial orientation has been shown to depend on stresses and strain, it is reasonable to conclude, from our findings, that osteocyte activity is mainly related to bone mechanical function rather than to the mineral metabolism of the animal species.
September
1996: 129% 169s
The 7th International
Congress
Abstracts of Bone Morphometry
119
121
BONE MINERAL DENSITY COMPARES AND CONTRASTS WITH THE BIOMECHANICAL MEASUREMENTS OF CANINE BONE. D. Pienkowski, J. McCarter. T. Doers, R. Maitra, M.-C. MonierFaugere,’ H.H. Malluche’ Divisions of Orthopaedic Surgery and ‘Nephrology, Bone and Mineral Metabolism, University of Kentucky, Lexington, KY, (USA).
DEVELOPMENT OF A NEURAL NETWORK-BASED COMPUTER AIDED DIAGNOSIS SYSTEM FOR A VERTEBRAL MORPHOMETRY WORKSTATION J.Redei, P.J. Countryman, H.K. Genant Osteoporosis Research Group, Univ. of California, San Francisco (USA)
Dual energy X-ray Absorptiometry measurements of Bone Mineral Density (BMD) are reproducible, precise, and some reports indicate that they are related to fracture rates in bone, however, measurement of material quantity (i.e., density) alone may not be a complete measure of bone’s mechanical competence. The objective of this study was to quantitatively compare the ability of BMD measurements to predict the mechanical properties of bone. Both tibiae, both femurs, and 3 vertebrae (Ll, L3, L5) from 254 retired female breeder beagle dogs were excised. BMDs of long bones were measured in 3 planes, and BMDs of vertebrae were measured in 2 planes. Long bones were potted and torqued to failure. Ll and L5 vertebrae were compressed to failure. Cancellous cores were obtained from L3 bones and these cores were compressed to failure. Maximum load, stiffness, and energy to failure were measured in both the torsional and compressive tests. BMD of the long bones was poorly correlated (r = 0.1, typically) with their torsional biomechanical properties. In contrast, the BMD of the vertebrae (both whole and cancellous cores) were well correlated (r = 0.6-0.6, typically, p < 0.001) with their compressive biomechanical properties. BMD could not predict the torsional biomechanical properties of long bones because these properties depend not only upon how much material is present (which BMD can measure) but upon the geometric distribution of this material in the bone (which BMD cannot measure). Since the compressive biomechanical properties of bone are virtually independent of the geometry of materials location, this explains the ability of BMD to predict these compressive mechanical properties. BMD is useful for predicting the mechanical competence of bones loaded in compression, but is insufficient to predict the mechanical competence of bones loaded in torsion.
159s
We have implemented a digital image workstation for semiquantitative and quantitative (6-point morphometry) Vertebral Fracture Assessment (VFA) on conventional radiographs, for large multicenter osteoporosis drug trials’. In this context. we are developing an Artificial Neural Network (ANN) approach for VFA using landmark (Bpoint) data derived from lateral spine radiographs. Previous studies* indicated that an ANN using vertebral height measurements may improve conventional morphometric VFA. However, the use of interlandmark distances (multivariate morphometrics) might not take full advantage of the information represented in the landmark configurations. We are investigating methods to further optimize the performance of the ANN. 400 postmenopausal osteopenic women ware evaluated. Several combinations of morphometric features previously explored by others (anterior, mid and posterior vertebral heights, mean vertebral depth, intervertebral disc area) and also xy-coordinates from T4 to L4 (converted by a rotation- and translation-invariant transform) were fed into the input layer. The ANN was trained on 314 of the sample according to a ‘gold standard (joint semiquant. reading by 4 expert radioloaists). and tested on the remaining l/4. This process tias repeated for the>ther 4 quarters of the set. The ‘best” coordinate-based ANN achieved overall sensitivities and specificities comparable to those of the height-based ANN; e.g. at decision threshold 0.4 for ‘fracture’, sens=652/699=72.5%; spec=4027/4272=94.3%. However, correlation between network outouts of both ANN was only moderate (r=0.66. y=O.66x+O.O2, n=51’71). Combination of both recoanizers achieved sens=61.6% and soec=94.4%. A new useful methodhas been developed which 1) takesinto accotmt the highly intercorrelated vertebral dimensions in an individual’s spinal column, 2) allows the presence of partially missing input data, and 3) provides a means for compensating for changing fracture prevalence. A method of using coordinates for detecting vertebral shape has been introduced. 1. RddeiJ. et al. In: Genant HK (ed). Vertebral fracture in osteoporosis: 293-306,1995 2. RCdeiJ, Jergas M, Li J, Ouyang X. Genant HK. J. Bone Miner. Res. 10 (SuppI1): s370
120
122
BONE REMODELING AND PLASMA BONE MARKERS IN PIGS FED CALCIUM DEFICIENT DIETS. A Pointrllart E. Eklou, C. Calm and E. Zerath. LNSA INRA. Jouy en Josas (France) and IMASSA, Bretrgny I Orge (France)
HISTOMORPHOMETRIC QUANTIFICATION OF OSTEOCYTE LACUNO-CANALICUAR CAVITIES IN VARIOUS TYPES OF BONE TISSUE IN DIFFERENT ANIMAL SPECIES. F. Remaaai, C. Palumbo, M. Ferretti, V. Cane Dipattimento di Scienze Motfologiche e Medico Legali Sezione di Anatomia Umana, Universita di Modena (Italy)
Calcrum IS one of the most Important nongenetic factors that influence peak bone mass Almost all rn viva changes rn bone formatron caused by calcium deficrency have been demonstrated in rats [l]. which is probably not the best model of human nutrition We have therefore carried out a bone hrstomorphometric study in pigs fed Cadeficient diets. Three groups of 6 pigs (9.5 f 0 4 kg body weight) were fed diets containing 0 1 (Very Low Ca. VLCa). 0 4 (Low Ca) or 1% Ca (Controls) for 32 days. Bone remodeling was analyzed by histomorphometry on distal metacarpal metaphyses and blood samples were collected at slaughter to monitor the parameters of bone metabolism: Ca. alkalme phosphatase activity (ALP), calcrtrlol (1,25D). PTH, osteocalcin (BGP) and the C-terminal propeptide of type I collagen (PICP). ALP2 l,25D3 PTH3 BGP’ PlCP5 Plasma Cal Control 9 9” Boa 97” 13= 202a 2 98 LowCa 9.7a 72= 26@ 23b 314f’ 3a 1216 517c 49= 332b 3.36 VLCa 6b I mgllOOml, 2 rull, 3 pglml. 4 nglml. 5 mg/l atb*c ~~0.05 or p
A comparative histomorphometric study was carried out on the extension of the osteocytic lacuna-canalicular network between various types of bone tissue in shaft bones of animal of different species (Frog, Chicken, Rabbit, Bovine, Horse, Dog, Man). In woven-fibered interstitial bone, and in parallel-fibered and lamellar Haversian systems the following parameters were measured, by an Image Analyzer on undecalcified sections viewed under transmitted ordinary light, reflected polarized light, and on scanning electron micrographs: a) volume of osteocyte lacunae; b) density of osteocyte lacunae and canaliculi; c) number per unit length of canaliculi in the wall of Haversian systems, in relation to the distance from the center of their canals; d) number of canaliculi departing from the opposite walls of lacunae. In all animal species, histomorphometric data show that: a) size and density of osteocyte lacunae as well as canalicular density are significantly higher in woven-fibered than in parallel-fibered and lamellar bone; b) in Haversian systems, the number of canaliculi departing from the lacunar walls facing the vascular canal is significantly higher than from the opposite walls; however, the canalicular density does not significantly change at different concentric levels of the osteonal walls. When comparing the same type of bone tissue in animal of different species, no significant differences were recorded in the values of all the above mentioned parameters. Briefly it appears that osteocyte lacunar size and density as well as canalicular density depend on collagen texture rather than on animal species, i.e. phylogenic evolution. Since collagen spatial orientation has been shown to depend on stresses and strain, it is reasonable to conclude, from our findings, that osteocyte activity is mainly related to bone mechanical function rather than to the mineral metabolism of the animal species.