- Email: [email protected]
50 Temperature Effects of Quantitative Ultrasound (QUS) Measurement in Osteoporosis Patients
Giuseppe and Toffanin
115
(Ca) with Sr. Since Sr attenuates x-rays more strongly than Ca, an overestimation of bone mineral density (BMD) is observed when using dual-energy x-ray absorptiometry (DXA). Pors Nielsen et al previously reported that a 1% molar concentration of Sr causes a 10% overestimation in BMD. This was supported by a more recent theoretical study carried out by Blake et al, who also observed that the ratio of %BMD overestimation to the %Sr present (the ‘strontium ratio’) is affected by the different effective photon energies of the x-ray beam. In the present in-vitro study, the strontium ratio for varying Sr concentrations was measured on two different DXA scanners. The principal aim of the study was to determine the difference in the Sr ratio arising from the different effective photon energies of the two scanners. Mixtures of calcium hydroxyapatite and strontium hydrogenphosphate were prepared in plastic dishes of 50 mm diameter with a constant total divalent cation concentration of 160 mmol. Sr cation concentration ranged from 0 to 9 mmol. The dishes were scanned beneath a water bath of 145 mm depth (to mimic soft tissue) using the Lunar Prodigy (GE Healthcare, Madison, WI) and Hologic Discovery (Hologic Inc., Bedford, MA) scanners (effective photon energies 38/75keV and 52/105keV respectively). Duplicate measurements were performed on separate days. The strontium ratio was calculated at each concentration for each scanner.
BMD
Sr2+ Substitution
[ BMD compared with no Sr2+
Strontium Ratio
Substitution
Lunar
Hologic
Lunar
Hologic
Lunar
Hologic
0.00% 1.00% 2.00% 3.00% 4.00% 5.63%
0.678 0.756 0.839 0.913 0.981 1.115
0.640 0.715 0.795 0.886 0.965 1.106
e 11.48% 23.60% 34.62% 44.64% 64.36%
e 11.77% 24.19% 38.44% 50.74% 72.85%
e 11.48 11.80 11.54 11.16 11.44
e 11.77 12.10 12.81 12.69 12.95
Our results show similar agreement to previously reported levels of BMD overestimation. We found the mean strontium ratio to be 11.55 and 12.63 for the Lunar and Hologic scanners respectively. The lower photon energies used on the Lunar scanner led to lesser BMD overestimation which is reflected in the lower Sr ratio (p ! 0.005).
48 ACCURACY OF DISCOVERY DUAL-ENERGY X-RAY DENSITOMETER TO ASSESS BMC AND BMD IN DIFFERENT STRAINS OF MICE H. Beaupied,1 A. Basillais,1 A. Malet,2 A. Blais,2 C. Elabd,3 A. Ez-Zoubir,3 A. Berdal,4 and L. Benhamou1, 1Inserm U658, Orleans, France, 2INRA, AgroParisTech, CNRH-IdF, UMR914, Paris, France, 3UMR CNRS 6543, Nice, France, 4Inserm U872, Paris, France; To apply on mice the analyses performed by dual-energy X ray densitometry (DXA), more adapted for human and rat, we needed to validate the technique. Three different strains of mice (C3H, C57BL/6 and CD1) were used to analyze the accuracy and precision of the Hologic QDR-Discovery densitometer to assess femur densitometry measurements. First, the bone mineral density (BMD, g.cm 2) and content (BMC, g) were measured ex vivo with the Discovery. Second, the femurs were burned to measure ash weight. Discovery measurement precision was assessed by calculating the root mean square average of the individual coefficients of variation (RMSCV, %) both with and without repositioning. The accuracy was estimated by comparing the BMC and BMD with ash weight. Linear regression analysis and the Bland and Altman’s method were used to assess the confidence between the two measurement methods. The RMSCV values were 3.99% for BMC and 6.84% for BMD with repositioning and 4.83% for BMC and 4.24% for BMD without repositioning. The linear regression analysis showed significant correlations between BMC and ash weight whatever the data were analyzed all together or strain by strain. Values of r 5 0.96, r 5 0.82, r 5 0.84 and r 5 0.93 for the Pearson coefficient were obtained for respectively the polled data, C3H, B6 and CD1 strains. The regression curves between ash weight and BMC were similar for the three strains. Therefore the relationship between ash weight and BMC was not affected by the mice strain. According to Bland and Altman’s method, there was no proportional error between both BMC and BMD and the ash weight for each mice strain. To conclude, the Discovery measurements were sufficiently precise and accurate to measure the BMC and BMD values of mice femurs.
Journal of Clinical Densitometry: Assessment of Skeletal Health
49 PERIPHERAL COMPUTED-TOMOGRAPHY SCANNER FOR HIGH-RESOLUTION IN-VIVO IMAGING OF TRABECULAR-BONE MICROARCHITECTURE S. Alladi S.K. Abhange and T.N. Hangartner, BioMedical Imaging Laboratory, Wright State University, Dayton, OH, USA; Trabecular number and density are accepted descriptors of bone status. Trabecular structures ranges from 50e200 mm. Imaging techniques to visualize them usually result in high radiation dose to the patient and have been limited mostly to in-vitro analysis of bone biopsies. The current project proposes the use of computedtomography based high-resolution imaging of trabecular structures, in-vivo, with an innovative technique to reduce dose. The dose reduction is achieved by collecting data for only a small volume of interest (1.5 cm 1.5 cm 1.5 cm) with high precision and resolution and for the remaining object at lower precision and resolution. Interpolation of data in the low-resolution region is used to compute the missing information required for reconstruction. Dose was calculated for pairs of factor reductions in photon count rate and resolution between the two datacollection regions. A savings of 37% -75% in dose was obtained using various reduction factors. The optimum cutback in count rate and resolution by a factor of 6 each yields a 74% savings in dose. Additional cutbacks do not result in significant changes in dose but further degrade the spatial resolution in the volume of interest. The effect of dose reduction on spatial resolution was simulated using a test phantom with circles of diameters 50-200 mm. In each resolution group, 16 circles were arranged in a square with the spacing equal to the diameter. Psycho-visual analysis established the effect of number of source positions and photon statistics on spatial resolution. The results show an improvement in spatial resolution with increasing number of photon counts and source positions. The average dose for a forearm image ranges from 500 mGy at 50 mm to 0.4 mGy at 200 mm for the optimal cases based on the established cutback factor of 6 in photon count rate and detector resolution.
50 TEMPERATURE EFFECTS OF QUANTITATIVE ULTRASOUND (QUS) MEASUREMENT IN OSTEOPOROSIS PATIENTS K. Yoh,1 H. Yokoi,2 T. Arai,3 and P. Bejrachandra4, 1Orthop. Dept. Hyogo College of Medicine, Sasayama Hospital, Hyogo, Japan, 2Takarazuka City Hospital, Takarazuka, Japan, 3Furuno Electric Co., Ltd., Japan, 4Radiological Tech., Chulalongkorn University, Bangkok, Thailand; Quantitative ultrasound (QUS) is widely used in cohort study and screening of osteoporosis because of its handy equipment and easy way without any invasive procedure. However, we still have no consensus of using QUS for monitoring osteoporosis treatment. Moreover, temperature is thought to influence the QUS measurement. To study the influence of temperature on QUS measurements in osteoporosis patients, we repeatedly measured QUS throughout one year to examine the relation between the room temperature and the heel skin temperature and SOS values by QUS. Objects and Methods: 128 osteoporosis patients (117 women and 11 men; mean age 75 9 years) were targeted. We measured the outside temperature, the room temperature and the heel surface and deep temperature by infrared thermometer and SOS. After the first measurement, the right foot was soaked in the hot bus at 40 C for 5 minutes and then measured again. We performed every two months, and measurements were repeated. CM100 and CM200 instruments (there was a function that could correct the SOS according to the heel temperature) were used in this study. Results and Discussions: The average outside temperature was 15 10 C, the room temperature was 23 2 C, the heel skin temperature was 27 4 C. A 20 m/second difference or more was seen in SOS in winter and summer, and high values were shown in winter. There was a significant relation between temperature and SOS values (p ! 0.05). The difference decreased to about the half when a hot bus was used. When we use QUS to monitor treatment of osteoporosis, we should considered the influence of the outside temperature and the temperature of the heel skin. We recommend to use instruments like CM200, which can correct the data according to the heel temperature.
51 DELAYED GROWTH AND SKELETAL MATURATION AFFECT BONE MINERAL STATUS ASSESSED BY PHALANGEAL QUANTITATIVE ULTRASOUND G.I. Baroncelli S. Bertelloni F. Vierucci S. Ghione and G. Saggese, Department of Pediatrics, University-Hospital, Pisa, Italy;
Volume 12, 2009
115
(Ca) with Sr. Since Sr attenuates x-rays more strongly than Ca, an overestimation of bone mineral density (BMD) is observed when using dual-energy x-ray absorptiometry (DXA). Pors Nielsen et al previously reported that a 1% molar concentration of Sr causes a 10% overestimation in BMD. This was supported by a more recent theoretical study carried out by Blake et al, who also observed that the ratio of %BMD overestimation to the %Sr present (the ‘strontium ratio’) is affected by the different effective photon energies of the x-ray beam. In the present in-vitro study, the strontium ratio for varying Sr concentrations was measured on two different DXA scanners. The principal aim of the study was to determine the difference in the Sr ratio arising from the different effective photon energies of the two scanners. Mixtures of calcium hydroxyapatite and strontium hydrogenphosphate were prepared in plastic dishes of 50 mm diameter with a constant total divalent cation concentration of 160 mmol. Sr cation concentration ranged from 0 to 9 mmol. The dishes were scanned beneath a water bath of 145 mm depth (to mimic soft tissue) using the Lunar Prodigy (GE Healthcare, Madison, WI) and Hologic Discovery (Hologic Inc., Bedford, MA) scanners (effective photon energies 38/75keV and 52/105keV respectively). Duplicate measurements were performed on separate days. The strontium ratio was calculated at each concentration for each scanner.
BMD
Sr2+ Substitution
[ BMD compared with no Sr2+
Strontium Ratio
Substitution
Lunar
Hologic
Lunar
Hologic
Lunar
Hologic
0.00% 1.00% 2.00% 3.00% 4.00% 5.63%
0.678 0.756 0.839 0.913 0.981 1.115
0.640 0.715 0.795 0.886 0.965 1.106
e 11.48% 23.60% 34.62% 44.64% 64.36%
e 11.77% 24.19% 38.44% 50.74% 72.85%
e 11.48 11.80 11.54 11.16 11.44
e 11.77 12.10 12.81 12.69 12.95
Our results show similar agreement to previously reported levels of BMD overestimation. We found the mean strontium ratio to be 11.55 and 12.63 for the Lunar and Hologic scanners respectively. The lower photon energies used on the Lunar scanner led to lesser BMD overestimation which is reflected in the lower Sr ratio (p ! 0.005).
48 ACCURACY OF DISCOVERY DUAL-ENERGY X-RAY DENSITOMETER TO ASSESS BMC AND BMD IN DIFFERENT STRAINS OF MICE H. Beaupied,1 A. Basillais,1 A. Malet,2 A. Blais,2 C. Elabd,3 A. Ez-Zoubir,3 A. Berdal,4 and L. Benhamou1, 1Inserm U658, Orleans, France, 2INRA, AgroParisTech, CNRH-IdF, UMR914, Paris, France, 3UMR CNRS 6543, Nice, France, 4Inserm U872, Paris, France; To apply on mice the analyses performed by dual-energy X ray densitometry (DXA), more adapted for human and rat, we needed to validate the technique. Three different strains of mice (C3H, C57BL/6 and CD1) were used to analyze the accuracy and precision of the Hologic QDR-Discovery densitometer to assess femur densitometry measurements. First, the bone mineral density (BMD, g.cm 2) and content (BMC, g) were measured ex vivo with the Discovery. Second, the femurs were burned to measure ash weight. Discovery measurement precision was assessed by calculating the root mean square average of the individual coefficients of variation (RMSCV, %) both with and without repositioning. The accuracy was estimated by comparing the BMC and BMD with ash weight. Linear regression analysis and the Bland and Altman’s method were used to assess the confidence between the two measurement methods. The RMSCV values were 3.99% for BMC and 6.84% for BMD with repositioning and 4.83% for BMC and 4.24% for BMD without repositioning. The linear regression analysis showed significant correlations between BMC and ash weight whatever the data were analyzed all together or strain by strain. Values of r 5 0.96, r 5 0.82, r 5 0.84 and r 5 0.93 for the Pearson coefficient were obtained for respectively the polled data, C3H, B6 and CD1 strains. The regression curves between ash weight and BMC were similar for the three strains. Therefore the relationship between ash weight and BMC was not affected by the mice strain. According to Bland and Altman’s method, there was no proportional error between both BMC and BMD and the ash weight for each mice strain. To conclude, the Discovery measurements were sufficiently precise and accurate to measure the BMC and BMD values of mice femurs.
Journal of Clinical Densitometry: Assessment of Skeletal Health
49 PERIPHERAL COMPUTED-TOMOGRAPHY SCANNER FOR HIGH-RESOLUTION IN-VIVO IMAGING OF TRABECULAR-BONE MICROARCHITECTURE S. Alladi S.K. Abhange and T.N. Hangartner, BioMedical Imaging Laboratory, Wright State University, Dayton, OH, USA; Trabecular number and density are accepted descriptors of bone status. Trabecular structures ranges from 50e200 mm. Imaging techniques to visualize them usually result in high radiation dose to the patient and have been limited mostly to in-vitro analysis of bone biopsies. The current project proposes the use of computedtomography based high-resolution imaging of trabecular structures, in-vivo, with an innovative technique to reduce dose. The dose reduction is achieved by collecting data for only a small volume of interest (1.5 cm 1.5 cm 1.5 cm) with high precision and resolution and for the remaining object at lower precision and resolution. Interpolation of data in the low-resolution region is used to compute the missing information required for reconstruction. Dose was calculated for pairs of factor reductions in photon count rate and resolution between the two datacollection regions. A savings of 37% -75% in dose was obtained using various reduction factors. The optimum cutback in count rate and resolution by a factor of 6 each yields a 74% savings in dose. Additional cutbacks do not result in significant changes in dose but further degrade the spatial resolution in the volume of interest. The effect of dose reduction on spatial resolution was simulated using a test phantom with circles of diameters 50-200 mm. In each resolution group, 16 circles were arranged in a square with the spacing equal to the diameter. Psycho-visual analysis established the effect of number of source positions and photon statistics on spatial resolution. The results show an improvement in spatial resolution with increasing number of photon counts and source positions. The average dose for a forearm image ranges from 500 mGy at 50 mm to 0.4 mGy at 200 mm for the optimal cases based on the established cutback factor of 6 in photon count rate and detector resolution.
50 TEMPERATURE EFFECTS OF QUANTITATIVE ULTRASOUND (QUS) MEASUREMENT IN OSTEOPOROSIS PATIENTS K. Yoh,1 H. Yokoi,2 T. Arai,3 and P. Bejrachandra4, 1Orthop. Dept. Hyogo College of Medicine, Sasayama Hospital, Hyogo, Japan, 2Takarazuka City Hospital, Takarazuka, Japan, 3Furuno Electric Co., Ltd., Japan, 4Radiological Tech., Chulalongkorn University, Bangkok, Thailand; Quantitative ultrasound (QUS) is widely used in cohort study and screening of osteoporosis because of its handy equipment and easy way without any invasive procedure. However, we still have no consensus of using QUS for monitoring osteoporosis treatment. Moreover, temperature is thought to influence the QUS measurement. To study the influence of temperature on QUS measurements in osteoporosis patients, we repeatedly measured QUS throughout one year to examine the relation between the room temperature and the heel skin temperature and SOS values by QUS. Objects and Methods: 128 osteoporosis patients (117 women and 11 men; mean age 75 9 years) were targeted. We measured the outside temperature, the room temperature and the heel surface and deep temperature by infrared thermometer and SOS. After the first measurement, the right foot was soaked in the hot bus at 40 C for 5 minutes and then measured again. We performed every two months, and measurements were repeated. CM100 and CM200 instruments (there was a function that could correct the SOS according to the heel temperature) were used in this study. Results and Discussions: The average outside temperature was 15 10 C, the room temperature was 23 2 C, the heel skin temperature was 27 4 C. A 20 m/second difference or more was seen in SOS in winter and summer, and high values were shown in winter. There was a significant relation between temperature and SOS values (p ! 0.05). The difference decreased to about the half when a hot bus was used. When we use QUS to monitor treatment of osteoporosis, we should considered the influence of the outside temperature and the temperature of the heel skin. We recommend to use instruments like CM200, which can correct the data according to the heel temperature.
51 DELAYED GROWTH AND SKELETAL MATURATION AFFECT BONE MINERAL STATUS ASSESSED BY PHALANGEAL QUANTITATIVE ULTRASOUND G.I. Baroncelli S. Bertelloni F. Vierucci S. Ghione and G. Saggese, Department of Pediatrics, University-Hospital, Pisa, Italy;
Volume 12, 2009