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Revised pediatric reference data for the lateral distal femur measured by Hologic Discovery/Delphi dual-energy X-ray absorptiometry.

Zemel BS, Stallings VA, Leonard MB, Paulhamus DR, Kecskemethy HH, Harcke HT, Henderson RC - J Clin Densitom (2009)

Bottom Line: Copyright 1997-2006, Medical Research Council, UK) and Z-scores calculated and compared by correlation analysis.Revised LDF reference curves were generated.The new LDF Z-scores were strongly and significantly associated with weight, body mass index, spine and whole body BMD Z-scores, and all pQCT Z-scores.

View Article: PubMed Central - PubMed

Affiliation: Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA 19104-4399, USA. Zemel@email.chop.edu

ABSTRACT
Lateral distal femur (LDF) scans by dual-energy X-ray absorptiometry (DXA) are often feasible in children for whom other sites are not measurable. Pediatric reference data for LDF are not available for more recent DXA technology. The objective of this study was to assess older pediatric LDF reference data, construct new reference curves for LDF bone mineral density (BMD), and demonstrate the comparability of LDF BMD to other measures of BMD and strength assessed by DXA and by peripheral quantitative computed tomography (pQCT). LDF, spine and whole body scans of 821 healthy children, 5-18 yr of age, recruited at a single center were obtained using a Hologic Discovery/Delphi system (Hologic, Inc., Bedford, MA). Tibia trabecular and total BMD (3% site), cortical geometry (38% site) (cortical thickness, section modulus, and strain-strength index) were assessed by pQCT. Sex- and race-specific reference curves were generated using LMS Chartmaker (LMS Chartmaker Pro, version 2.3. Tim Cole and Huiqi Pan. Copyright 1997-2006, Medical Research Council, UK) and Z-scores calculated and compared by correlation analysis. Z-scores for LDF BMD based on published findings demonstrated overestimation or underestimation of the prevalence of low BMD-for-age depending on the region of interest considered. Revised LDF reference curves were generated. The new LDF Z-scores were strongly and significantly associated with weight, body mass index, spine and whole body BMD Z-scores, and all pQCT Z-scores. These findings demonstrate the comparability of LDF measurements to other clinical and research bone density assessment modes, and enable assessment of BMD in children with disabilities, who are particularly prone to low trauma fractures of long bones, and for whom traditional DXA measurement sites are not feasible.

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Related in: MedlinePlus

(A) Patient positioning for the left lateral distal femur scan showing the child in a side-lying position with positioning devices (foam blocks and sand bags) to assist in attaining a comfortable and stable position. The femur is centered on the table and parallel to the edge. The forearm scan mode is used to obtain the scan. (B) Analysis of the scan requires insertion of region of interest boxes. The width and height of each region of interest box is illustrated in the figure. (C) The three regions of interest are illustrated in the figure.
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Figure 1: (A) Patient positioning for the left lateral distal femur scan showing the child in a side-lying position with positioning devices (foam blocks and sand bags) to assist in attaining a comfortable and stable position. The femur is centered on the table and parallel to the edge. The forearm scan mode is used to obtain the scan. (B) Analysis of the scan requires insertion of region of interest boxes. The width and height of each region of interest box is illustrated in the figure. (C) The three regions of interest are illustrated in the figure.

Mentions: The lateral distal femur scan was obtained as described in Henderson et al. 21; positioning of the subject is illustrated in Figure 1a, and placement of the regions of interest (ROIs) is shown in Figures 1b and 1c. Briefly, the patient is placed in a side lying position on the scanning table, on the side being measured, with the femur following the length of the table. The other thigh is flexed out of the field of view. The lateral distal femur is analyzed for three regions of interest: region 1 is placed at the anterior half of distal metaphysis, region two is metadiaphyseal, and region 3 is diaphyseal. Region size is based on the diaphyseal width; all three regions are the same height. To assure consistency in lateral distal femur scan acquisition and analysis techniques, a subset of 40 randomly selected scans were reviewed by an independent investigator (HK). In addition, all scans were inspected by one investigator (BZ) for movement, interfering factors, and analysis consistency (placement of regions of interest) to assure technical quality of all scans.


Revised pediatric reference data for the lateral distal femur measured by Hologic Discovery/Delphi dual-energy X-ray absorptiometry.

Zemel BS, Stallings VA, Leonard MB, Paulhamus DR, Kecskemethy HH, Harcke HT, Henderson RC - J Clin Densitom (2009)

(A) Patient positioning for the left lateral distal femur scan showing the child in a side-lying position with positioning devices (foam blocks and sand bags) to assist in attaining a comfortable and stable position. The femur is centered on the table and parallel to the edge. The forearm scan mode is used to obtain the scan. (B) Analysis of the scan requires insertion of region of interest boxes. The width and height of each region of interest box is illustrated in the figure. (C) The three regions of interest are illustrated in the figure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4641747&req=5

Figure 1: (A) Patient positioning for the left lateral distal femur scan showing the child in a side-lying position with positioning devices (foam blocks and sand bags) to assist in attaining a comfortable and stable position. The femur is centered on the table and parallel to the edge. The forearm scan mode is used to obtain the scan. (B) Analysis of the scan requires insertion of region of interest boxes. The width and height of each region of interest box is illustrated in the figure. (C) The three regions of interest are illustrated in the figure.
Mentions: The lateral distal femur scan was obtained as described in Henderson et al. 21; positioning of the subject is illustrated in Figure 1a, and placement of the regions of interest (ROIs) is shown in Figures 1b and 1c. Briefly, the patient is placed in a side lying position on the scanning table, on the side being measured, with the femur following the length of the table. The other thigh is flexed out of the field of view. The lateral distal femur is analyzed for three regions of interest: region 1 is placed at the anterior half of distal metaphysis, region two is metadiaphyseal, and region 3 is diaphyseal. Region size is based on the diaphyseal width; all three regions are the same height. To assure consistency in lateral distal femur scan acquisition and analysis techniques, a subset of 40 randomly selected scans were reviewed by an independent investigator (HK). In addition, all scans were inspected by one investigator (BZ) for movement, interfering factors, and analysis consistency (placement of regions of interest) to assure technical quality of all scans.

Bottom Line: Copyright 1997-2006, Medical Research Council, UK) and Z-scores calculated and compared by correlation analysis.Revised LDF reference curves were generated.The new LDF Z-scores were strongly and significantly associated with weight, body mass index, spine and whole body BMD Z-scores, and all pQCT Z-scores.

View Article: PubMed Central - PubMed

Affiliation: Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA 19104-4399, USA. Zemel@email.chop.edu

ABSTRACT
Lateral distal femur (LDF) scans by dual-energy X-ray absorptiometry (DXA) are often feasible in children for whom other sites are not measurable. Pediatric reference data for LDF are not available for more recent DXA technology. The objective of this study was to assess older pediatric LDF reference data, construct new reference curves for LDF bone mineral density (BMD), and demonstrate the comparability of LDF BMD to other measures of BMD and strength assessed by DXA and by peripheral quantitative computed tomography (pQCT). LDF, spine and whole body scans of 821 healthy children, 5-18 yr of age, recruited at a single center were obtained using a Hologic Discovery/Delphi system (Hologic, Inc., Bedford, MA). Tibia trabecular and total BMD (3% site), cortical geometry (38% site) (cortical thickness, section modulus, and strain-strength index) were assessed by pQCT. Sex- and race-specific reference curves were generated using LMS Chartmaker (LMS Chartmaker Pro, version 2.3. Tim Cole and Huiqi Pan. Copyright 1997-2006, Medical Research Council, UK) and Z-scores calculated and compared by correlation analysis. Z-scores for LDF BMD based on published findings demonstrated overestimation or underestimation of the prevalence of low BMD-for-age depending on the region of interest considered. Revised LDF reference curves were generated. The new LDF Z-scores were strongly and significantly associated with weight, body mass index, spine and whole body BMD Z-scores, and all pQCT Z-scores. These findings demonstrate the comparability of LDF measurements to other clinical and research bone density assessment modes, and enable assessment of BMD in children with disabilities, who are particularly prone to low trauma fractures of long bones, and for whom traditional DXA measurement sites are not feasible.

Show MeSH
Related in: MedlinePlus