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A method for determining skeletal lengths from DXA images.

Chinappen-Horsley U, Blake GM, Fogelman I, Spector TD - BMC Musculoskelet Disord (2007)

Bottom Line: Also, the time taken to use LPC was half that of RET at 5 minutes per scan.Skeletal ratios can be accurately and precisely measured from DXA total body scan images.This new phenotype will be useful for osteoporosis research for individuals or large-scale epidemiological or genetic studies.

View Article: PubMed Central - HTML - PubMed

Affiliation: King's College London, St Thomas' Hospital Campus, Twin Research & Genetic Epidemiology Unit, Lambeth Palace Road, London, SE1 7EH, UK. usha.chinappen@kcl.ac.uk

ABSTRACT

Background: Skeletal ratios and bone lengths are widely used in anthropology and forensic pathology and hip axis length is a useful predictor of fracture. The aim of this study was to show that skeletal ratios, such as length of femur to height, could be accurately measured from a DXA (dual energy X-ray absorptiometry) image.

Methods: 90 normal Caucasian females, 18-80 years old, with whole body DXA data were used as subjects. Two methods, linear pixel count (LPC) and reticule and ruler (RET) were used to measure skeletal sizes on DXA images and compared with real clinical measures from 20 subjects and 20 x-rays of the femur and tibia taken in 2003.

Results: Although both methods were highly correlated, the LPC inter- and intra-observer error was lower at 1.6% compared to that of RET at 2.3%. Both methods correlated positively with real clinical measures, with LPC having a marginally stronger correlation coefficient (r2 = 0.94; r2 = 0.84; average r2 = 0.89) than RET (r2 = 0.86; r2 = 0.84; average r2 = 0.85) with X-rays and real measures respectively. Also, the time taken to use LPC was half that of RET at 5 minutes per scan.

Conclusion: Skeletal ratios can be accurately and precisely measured from DXA total body scan images. The LPC method is easy to use and relatively rapid. This new phenotype will be useful for osteoporosis research for individuals or large-scale epidemiological or genetic studies.

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DXA Imaging: Comparing LPC & RET. A) Total body DXA image from Hologic QDR-4500W indicating cut-off points (small black horizontal lines) at each measurement site – height was measured from the crown to the heel; B) LPC measure of femur from which number of horizontal lines are automatically calculated as vertical heright of ROI; C) Reticule with its millimetre scale placed over paper image of femur, for RET measurement.
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Figure 1: DXA Imaging: Comparing LPC & RET. A) Total body DXA image from Hologic QDR-4500W indicating cut-off points (small black horizontal lines) at each measurement site – height was measured from the crown to the heel; B) LPC measure of femur from which number of horizontal lines are automatically calculated as vertical heright of ROI; C) Reticule with its millimetre scale placed over paper image of femur, for RET measurement.

Mentions: The RET (reticule and ruler) method involved placing the ruler over the consistently sized paper image to measure standing height, from crown to heel, and then positioning the reticule carefully over regional lengths to measure bone sizes. LPC (linear pixel count) was the number of vertical pixels giving the length of the bone. The ROI was a rectangular box for all sites and was adjusted according to the size of the bone (Figure 1).


A method for determining skeletal lengths from DXA images.

Chinappen-Horsley U, Blake GM, Fogelman I, Spector TD - BMC Musculoskelet Disord (2007)

DXA Imaging: Comparing LPC & RET. A) Total body DXA image from Hologic QDR-4500W indicating cut-off points (small black horizontal lines) at each measurement site – height was measured from the crown to the heel; B) LPC measure of femur from which number of horizontal lines are automatically calculated as vertical heright of ROI; C) Reticule with its millimetre scale placed over paper image of femur, for RET measurement.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211289&req=5

Figure 1: DXA Imaging: Comparing LPC & RET. A) Total body DXA image from Hologic QDR-4500W indicating cut-off points (small black horizontal lines) at each measurement site – height was measured from the crown to the heel; B) LPC measure of femur from which number of horizontal lines are automatically calculated as vertical heright of ROI; C) Reticule with its millimetre scale placed over paper image of femur, for RET measurement.
Mentions: The RET (reticule and ruler) method involved placing the ruler over the consistently sized paper image to measure standing height, from crown to heel, and then positioning the reticule carefully over regional lengths to measure bone sizes. LPC (linear pixel count) was the number of vertical pixels giving the length of the bone. The ROI was a rectangular box for all sites and was adjusted according to the size of the bone (Figure 1).

Bottom Line: Also, the time taken to use LPC was half that of RET at 5 minutes per scan.Skeletal ratios can be accurately and precisely measured from DXA total body scan images.This new phenotype will be useful for osteoporosis research for individuals or large-scale epidemiological or genetic studies.

View Article: PubMed Central - HTML - PubMed

Affiliation: King's College London, St Thomas' Hospital Campus, Twin Research & Genetic Epidemiology Unit, Lambeth Palace Road, London, SE1 7EH, UK. usha.chinappen@kcl.ac.uk

ABSTRACT

Background: Skeletal ratios and bone lengths are widely used in anthropology and forensic pathology and hip axis length is a useful predictor of fracture. The aim of this study was to show that skeletal ratios, such as length of femur to height, could be accurately measured from a DXA (dual energy X-ray absorptiometry) image.

Methods: 90 normal Caucasian females, 18-80 years old, with whole body DXA data were used as subjects. Two methods, linear pixel count (LPC) and reticule and ruler (RET) were used to measure skeletal sizes on DXA images and compared with real clinical measures from 20 subjects and 20 x-rays of the femur and tibia taken in 2003.

Results: Although both methods were highly correlated, the LPC inter- and intra-observer error was lower at 1.6% compared to that of RET at 2.3%. Both methods correlated positively with real clinical measures, with LPC having a marginally stronger correlation coefficient (r2 = 0.94; r2 = 0.84; average r2 = 0.89) than RET (r2 = 0.86; r2 = 0.84; average r2 = 0.85) with X-rays and real measures respectively. Also, the time taken to use LPC was half that of RET at 5 minutes per scan.

Conclusion: Skeletal ratios can be accurately and precisely measured from DXA total body scan images. The LPC method is easy to use and relatively rapid. This new phenotype will be useful for osteoporosis research for individuals or large-scale epidemiological or genetic studies.

Show MeSH
Related in: MedlinePlus