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Evaluation of three spine phantoms for DXA QC
48S
Abstracts
P 65 EVALUATION OF THREE SPINE PHANTOMS FOR DXA QC. N Culton, N Pocock. St. Vincent's Hospital, Sydney. We evaluated the use of three commercially available spine phantoms to monitor the stability of the Lunar DPXL and Lunar Expert. The phantoms used were the Lunar aluminium/water bath (LB) (Lunar, Madison WI), the Hologic anthropomorphic spine (HS) (Hologic, Waltham MA), and the Bona Fide aluminiurrdresin spine (BF) (Bona Fide, Madison WI). Short term precision was assessed from 10 consecutive scans without moving the phantom. Phantoms were scanned each day for approximately 8 months (120 scans). The initial 20 scans were used to establish individual means, standard deviations (SD) and co-efficient of variations (CV%) for BMD and area. Data were assessed using Shewart rules, running mean and visual inspection of a scatlergram, with lines at 1, 2, 3 and 4SD. All phantoms demonstrated small in-vitro CV%s ranging from 0.24% to 0.90%. Variability in area (CV%) ranged from 0.23% to 0.42%. ANOVA did not detect any significant difference between the initial 20 scans or short term precision data among the different phantoms. There were however differences in QC monitoring over the 120 scans between the LB and BF on the DPXL and between all phantoms on the Expert. Shewart analysis showed agreement of a failure, between two or more phantoms, 7 times on the DPXL (LB and BF) and l event on the Expert (all phantoms). The LB showed the greatest number of false positive events on Shewart analysis with 9 and 7 events on the DPXL and Expert respectively. Running means showed a decrease of over ISD on the DPXL which was only shown by the LB and BF and a decrease in the running means on the Expert shown by the LB and HS however this did not reach significance (1SD). All three phantoms assessed in this study are satisfactory for use in DXA monitoring. Operators must be aware of limitations of QC analysis, including high false positive rate when using Shewarts analysis, and the dependence of BMD result on reported area.
P 67 PREVALENT APPENDICULAR FRACTURES 1N ELDERLY WOMEN ARE ASSOCIATED WITH LOW DEXA AND ULTRASOUND MEASUREMENTS A Marangou, A Devine, S Dhaliwal, RL Prince Dept. Medicine, University of Western Australia and Dept. Endocrinology & Diabetes, Sir Charles Gairdner Hospital, Perth, Western Australia. The aims of this study were to examine whether there is evidence of skeletal insufficiency as determined by quantitative ultrasound (QUS) and DEXA measurements in women with or without appendicular fractures. The study group consisted of 1380 women age 75~-3y (mean ±SD) recruited at random from the population over 70 using the electoral roll. They were divided into three groups according to fracture status: 66% had zero, 13% had 1 and 22% had >_2 osteoporotic fractures. Calcaneal QUS (Lunar Achilles) and DEXA (Hologic 4500A) bone mineral density at the spine and hip and body composition (fat and lean) were measured. Significant differences between fracture groups were determined by one-way ANOVA. Mean age, BMI, body composition and grip strength of the subjects were not different between the 3 groups. Mean years since menopause was significantly longer in the multiple fracture group (28i7y) compared to the other two groups (27±6y). Bone density was significantly lower in the multiple fracture group by approximately half a SD compared to the non/single fracture groups [BUA 98a-7 vs 101±8 dB/MHz, P < 0.001; SOS 1503±22 vs 1514±26 m/s,P < 0001: Stiffness 66±10 vs 71±11%, P<0.001; DEXA total hip BMD 0.79±0 12 vs 0.84±0.11 mg/cm z, P < 0 0 2 and DEXA neck of femur BMD 0.66±0.10 vs 0.70±0.10 mg/cm 2, P < 0.008. We conclude that patients with prevalent appendicular fractures have no defect in body composition or muscle strength but have skeletal insufficiency as determined by low DEXA and QUS measurements and thus may respond to agents that improve skeletal structure.
Bone Vol. 27, No. 4, Supplement October 2000: IS-54S
P 66 C A L C A N E A L QUS IN M A L E S AND F E M A L E S W I T H HIP FRACTURE. Pocock N*, Culton N, Gilbert G, Hoy M, Chu J, Freund J. St Vincent's and Liverpool Hospitals, Sydney, NSW, Australia. Calcaneal quantitative ultrasound (QUS) has been demonstrated as an independent risk factor for hip fracture in females over 65 years of age. There is little data on the role of QUS in hip fracture in males. We obtained calcaneal BUA using a QUS2 (Metra Biosystems, Mountain View, CA) ultrasound densitometer in 25 subjects (9 males and 16 females) with recent hip fractures. Calcaneal scans were obtained within a mean of 8 (+6) days of the hip fracture. The non fractured leg was measured. The results are shown in the table. The male calcaneal T scores were obtained using the female reference range. n Males Females
9 16
Age Mean (SD) 80 (5.6) 76 (8.6)
BUA T score (mean + SD) Mean (SD) (Female refrange) 66 (14.8) -l.9 (1.2) 49 (8.3) -3.1 (0.6)
The mean male BUA was significantly higher than the mean female BUA (P<0.001), although there was significant overlap between the two groups. There was no significant difference in age between the males and females. There is currently some debate relating to the appropriate gender reference range for use in the interpretation of axial BMD in males. The preliminary data from the current study suggest that it may be inappropriate to apply a female QUS reference range to males to assess fracture risk.
P 68 D I S C O R D A N T N O R M A L RANGES FOR FEMORAL N E C K BMD IN AUSTRALIA. Pocock N, Cultun N, Noakes K, Harmelin D. St Vineent's Hospital, Sydney, Australia. Interpretation of DXA requires clearly defined reference ranges (RR). We assessed the reference ranges currently in use for femoral neck (FN) BMD in Australia. Representative proximal femur scans were obtained from 77 centres across Australia. FN BMD was standardised using published conversion equations and corresponding T scores calculated using an Australian RR (Ae.~) developed in Geelong, and using the NHANES-III RR (NH3m~). Reported T scores (TR) from the DXA centres, were compared to T scores derived from the N H 3 ~ (TNH), and from the A ~ (TA). A number of centres with Norland or Hologic scanners were using RR which differed significantly from both the NH3r~ and ApR. These different RR, result in a mean TR 0.71 standard deviations (SD) below the corresponding TNrl, (p<0.001) and 0.72 SD below the corresponding TA (p<0.001). Examination of the regression lines, comparing TR with TNH, and TR with TA. demonstrated that the RR being used by Lunar, and the remaining Norland and Hologic instruments, also differ slightly from both the N H 3 ~ and the AM. At T scores between -2.5 and ~4.0 the mean difference of TR in centres using Lunar scanners, from the corresponding TNH or from the corresponding TA were 0.07 (p<0.003) and 0.23 (p<0.001) respectively. The N H 3 ~ was compared to the Av.R using a set of BMD values, covering the clinical range. TNH scores were calculated and compared to the corresponding T^. There was close agreement between the TN. and corresponding TA. There are significant differences in the reference ranges currently used within Australia for interpretation o f F N BMD. The Ae.R for FN does not differ significantly from the N H 3 ~ , and is recommended as the most appropriate reference range in Australia.
Abstracts
P 65 EVALUATION OF THREE SPINE PHANTOMS FOR DXA QC. N Culton, N Pocock. St. Vincent's Hospital, Sydney. We evaluated the use of three commercially available spine phantoms to monitor the stability of the Lunar DPXL and Lunar Expert. The phantoms used were the Lunar aluminium/water bath (LB) (Lunar, Madison WI), the Hologic anthropomorphic spine (HS) (Hologic, Waltham MA), and the Bona Fide aluminiurrdresin spine (BF) (Bona Fide, Madison WI). Short term precision was assessed from 10 consecutive scans without moving the phantom. Phantoms were scanned each day for approximately 8 months (120 scans). The initial 20 scans were used to establish individual means, standard deviations (SD) and co-efficient of variations (CV%) for BMD and area. Data were assessed using Shewart rules, running mean and visual inspection of a scatlergram, with lines at 1, 2, 3 and 4SD. All phantoms demonstrated small in-vitro CV%s ranging from 0.24% to 0.90%. Variability in area (CV%) ranged from 0.23% to 0.42%. ANOVA did not detect any significant difference between the initial 20 scans or short term precision data among the different phantoms. There were however differences in QC monitoring over the 120 scans between the LB and BF on the DPXL and between all phantoms on the Expert. Shewart analysis showed agreement of a failure, between two or more phantoms, 7 times on the DPXL (LB and BF) and l event on the Expert (all phantoms). The LB showed the greatest number of false positive events on Shewart analysis with 9 and 7 events on the DPXL and Expert respectively. Running means showed a decrease of over ISD on the DPXL which was only shown by the LB and BF and a decrease in the running means on the Expert shown by the LB and HS however this did not reach significance (1SD). All three phantoms assessed in this study are satisfactory for use in DXA monitoring. Operators must be aware of limitations of QC analysis, including high false positive rate when using Shewarts analysis, and the dependence of BMD result on reported area.
P 67 PREVALENT APPENDICULAR FRACTURES 1N ELDERLY WOMEN ARE ASSOCIATED WITH LOW DEXA AND ULTRASOUND MEASUREMENTS A Marangou, A Devine, S Dhaliwal, RL Prince Dept. Medicine, University of Western Australia and Dept. Endocrinology & Diabetes, Sir Charles Gairdner Hospital, Perth, Western Australia. The aims of this study were to examine whether there is evidence of skeletal insufficiency as determined by quantitative ultrasound (QUS) and DEXA measurements in women with or without appendicular fractures. The study group consisted of 1380 women age 75~-3y (mean ±SD) recruited at random from the population over 70 using the electoral roll. They were divided into three groups according to fracture status: 66% had zero, 13% had 1 and 22% had >_2 osteoporotic fractures. Calcaneal QUS (Lunar Achilles) and DEXA (Hologic 4500A) bone mineral density at the spine and hip and body composition (fat and lean) were measured. Significant differences between fracture groups were determined by one-way ANOVA. Mean age, BMI, body composition and grip strength of the subjects were not different between the 3 groups. Mean years since menopause was significantly longer in the multiple fracture group (28i7y) compared to the other two groups (27±6y). Bone density was significantly lower in the multiple fracture group by approximately half a SD compared to the non/single fracture groups [BUA 98a-7 vs 101±8 dB/MHz, P < 0.001; SOS 1503±22 vs 1514±26 m/s,P < 0001: Stiffness 66±10 vs 71±11%, P<0.001; DEXA total hip BMD 0.79±0 12 vs 0.84±0.11 mg/cm z, P < 0 0 2 and DEXA neck of femur BMD 0.66±0.10 vs 0.70±0.10 mg/cm 2, P < 0.008. We conclude that patients with prevalent appendicular fractures have no defect in body composition or muscle strength but have skeletal insufficiency as determined by low DEXA and QUS measurements and thus may respond to agents that improve skeletal structure.
Bone Vol. 27, No. 4, Supplement October 2000: IS-54S
P 66 C A L C A N E A L QUS IN M A L E S AND F E M A L E S W I T H HIP FRACTURE. Pocock N*, Culton N, Gilbert G, Hoy M, Chu J, Freund J. St Vincent's and Liverpool Hospitals, Sydney, NSW, Australia. Calcaneal quantitative ultrasound (QUS) has been demonstrated as an independent risk factor for hip fracture in females over 65 years of age. There is little data on the role of QUS in hip fracture in males. We obtained calcaneal BUA using a QUS2 (Metra Biosystems, Mountain View, CA) ultrasound densitometer in 25 subjects (9 males and 16 females) with recent hip fractures. Calcaneal scans were obtained within a mean of 8 (+6) days of the hip fracture. The non fractured leg was measured. The results are shown in the table. The male calcaneal T scores were obtained using the female reference range. n Males Females
9 16
Age Mean (SD) 80 (5.6) 76 (8.6)
BUA T score (mean + SD) Mean (SD) (Female refrange) 66 (14.8) -l.9 (1.2) 49 (8.3) -3.1 (0.6)
The mean male BUA was significantly higher than the mean female BUA (P<0.001), although there was significant overlap between the two groups. There was no significant difference in age between the males and females. There is currently some debate relating to the appropriate gender reference range for use in the interpretation of axial BMD in males. The preliminary data from the current study suggest that it may be inappropriate to apply a female QUS reference range to males to assess fracture risk.
P 68 D I S C O R D A N T N O R M A L RANGES FOR FEMORAL N E C K BMD IN AUSTRALIA. Pocock N, Cultun N, Noakes K, Harmelin D. St Vineent's Hospital, Sydney, Australia. Interpretation of DXA requires clearly defined reference ranges (RR). We assessed the reference ranges currently in use for femoral neck (FN) BMD in Australia. Representative proximal femur scans were obtained from 77 centres across Australia. FN BMD was standardised using published conversion equations and corresponding T scores calculated using an Australian RR (Ae.~) developed in Geelong, and using the NHANES-III RR (NH3m~). Reported T scores (TR) from the DXA centres, were compared to T scores derived from the N H 3 ~ (TNH), and from the A ~ (TA). A number of centres with Norland or Hologic scanners were using RR which differed significantly from both the NH3r~ and ApR. These different RR, result in a mean TR 0.71 standard deviations (SD) below the corresponding TNrl, (p<0.001) and 0.72 SD below the corresponding TA (p<0.001). Examination of the regression lines, comparing TR with TNH, and TR with TA. demonstrated that the RR being used by Lunar, and the remaining Norland and Hologic instruments, also differ slightly from both the N H 3 ~ and the AM. At T scores between -2.5 and ~4.0 the mean difference of TR in centres using Lunar scanners, from the corresponding TNH or from the corresponding TA were 0.07 (p<0.003) and 0.23 (p<0.001) respectively. The N H 3 ~ was compared to the Av.R using a set of BMD values, covering the clinical range. TNH scores were calculated and compared to the corresponding T^. There was close agreement between the TN. and corresponding TA. There are significant differences in the reference ranges currently used within Australia for interpretation o f F N BMD. The Ae.R for FN does not differ significantly from the N H 3 ~ , and is recommended as the most appropriate reference range in Australia.