Bone ultrasound velocity in neonates with intrauterine growth deficit reflects a growth continuum.

Both bone mass by densitometry and speed of sound (SOS) from quantitative ultrasound of the bone (QUS) are directly related to bone strength. However, reports of lower bone mass but higher SOS in neonates with intrauterine growth deficit lead to apparent contradictory conclusions on bone strength. Three groups of infants were studied: small for gestation (SGA) with birth weights ≤10th percentile for gestation and 2 control groups with appropriate birth weights (11th to 90th percentile) for gestation (AGA): matched to SGA group for gestation and birth weight, respectively. SOS was measured with a commercial QUS instrument (Sunlight Omnisense 7000, Sunlight Medical Ltd, Tel Aviv, Israel) and 2 manufacturer supplied ultrasound probes (CS and CR) for small bones. The SGA group had significantly (p<0.01) higher SOS compared with weight matched but gestational less matured control group by an average of 54m/s with the CS probe and 80m/s with the CR probe but not significantly different from gestation-matched AGA group. SOS values from both probes were significantly correlated (r=0.71-0.91) but were significantly different between probes. Probe failure occurred with both probes. We conclude that QUS SOS values in SGA neonates are a reflection of a continuum of intrauterine maturation of the skeleton.

Effect of subcutaneous fat on quantitative bone ultrasound in chicken and neonates.

Bone quantitative ultrasound generated speed of sound (SOS) is a marker of bone strength. However, critical evaluation of its validity for use in small bones is extremely limited, and SOS data may not be consistent with data obtained from dual energy x ray absorptiometry, another marker of bone strength. We report the SOS values pre and postinjection of s.c. fat using a chicken bone model; and in large for gestation and appropriate for gestation neonates to determine the influence of s.c. fat. Average SOS were lowered for the chicken bones postfat injection by 36 m/s (CS probe) and 58 m/s (CR probe), and in large for gestation group by 75 m/s (CS probe) and 51 m/s (CR probe) (p = 0.03-0.004 paired t test) although SOS measurements from each probe are significantly correlated within the large (r = 0.78) and appropriate (r = 0.83) for gestation group. Failed SOS measurements occurred significantly more frequently in the postinjection studies regardless of the probe used in the chicken bone model and for the CS probe in large for gestation neonates. The lowered bone quantitative ultrasound measurements in large for gestation neonates is likely a measurement artifact from increased s.c. fat.

Quantitative bone US measurements in neonates and their mothers.

BACKGROUND: Factors that affect quantitative ultrasound (QUS) bone measurements have not been clearly defined for all clinical populations. OBJECTIVE: To determine some technical and clinical aspects that may affect QUS bone measurement in the neonate-maternal dyad. MATERIALS AND METHODS: Speed of sound (SOS) was measured at the radius and tibia using a commercial multisite axial transmission QUS instrument and three manufacturer-provided probes (CS, CR and CM). RESULTS: The study included 183 singleton neonates and 159 mothers. The type of probe, weight and edema significantly affected SOS measurements. In infants, the CS and CR probes measured SOS consistently at the tibia but not the radius. Gestational age was predictive of SOS from the CS probe and remained significant when race, gender, and birth weight were included. None of these parameters predicted SOS when using the CR probe. Maternal SOS at the radius and tibia was correlated with the CM probe. Maternal SOS was predicted by age but not by gravid status, number of living children, or race. There was no consistent correlation between maternal-infant dyad SOS measurements. CONCLUSIONS: Axial transmission SOS of bone varies with probe and site and is affected by technical and clinical factors. Valid data depend on documentation of the probes used and the clinical population studied.

Developmental variations in plasma leptin, leptin soluble receptor and their molar ratio in healthy infants.

BACKGROUND: Leptin and its soluble receptor (sOB-R) are important to regulation of body composition but there are no data on the developmental variations in these plasma variables and their relationship with body composition measurements, METHODS: Weight, length, and body composition (bone, fat and lean mass) by dual energy absorptiometry, and plasma variables were measured in healthy infants at 2, 4, 8 and 12 months. RESULTS: 15 whites and 29 African Americans (21 males and 23 females) with mean birth weight 3357 +/- 45 (SEM) g and gestation of 39.3 +/- 0.17 weeks were studied. The overall Z score for weight, length and weight for length during the study were 0.00 +/- 0.15, -0.08 +/- 0.11 and 0.12 +/- 0.14 respectively. With increasing age, plasma leptin (1.0 to 18.2, median 5.5 ng/mL) and sOB-R:leptin molar ratio (10.1 to 247.4, median 59.9) were lowered (r = -0.47, p < 0.01; and r = -0.37, p < 0.05 respectively), best predicted by weight Z score and percentage of fat mass, and higher in African American and female. Presence of body composition measurements eliminated the race and gender effect on the plasma variables. Plasma sOB-R (49.5 to 173.9, median 81.3 ng/mL) did not change significantly with age and was correlated and predicted only by body composition measurements. CONCLUSION: In healthy growing infants, plasma leptin but not sOB-R decreases with age. Gender, race and anthropometric measurements are additional physiological determinants predictive of plasma leptin and the receptor:ligand ratio. However, body composition is the only variable that can predict plasma leptin and its soluble receptor and the receptor: ligand ratio; and body composition measurements eliminated the race and gender effect on these plasma variables.

Anthropometric status in Palestinian children living in refugee camps in Lebanon.

OBJECTIVE: To study the relationship between anthropometric measurements and living conditions in infants and children living in refugee camps. DESIGN: Cross-sectional study. SETTING: Four Palestinian refugee camps in Lebanon. SUBJECTS: Thirty-three infants younger than two years of age and 234 children (106 males) younger than 15 years of age. METHODS: Weight and height were measured. Body mass index (BMI) was calculated as weight (kg)/length squared (m2). A parent of the subject answered a questionnaire on employment status, household size, food, and financial assistance as well as child's food consumption. RESULTS: Anthropometric measurements were standardized to the National Center of Health Statistics (NCHS) growth data as age- and sex-specific Z scores. No significant difference was seen between males and females. For all sites studied, the Z scores for weight (WAZ) and height (HAZ) of infants were not significantly different from zero. Among older children, WAZ, HAZ, and Z scores for BMI (BMIZ) were significantly less than zero. In infants, exclusive breast feeding, in addition to receiving financial help, correlated positively while meat and fruit consumption of less than three times per week correlated negatively with WAZ and HAZ. In older children, a mixed relationship was seen among the number of children younger than 10 years of age in a household, the child's meat, vegetable, and fruit consumption less than three times per week, and WAZ and HAZ. CONCLUSION: Living conditions and socioeconomic restrictions on Palestinian refugees living in Lebanon do not appear to influence growth of infants younger than two years of age but may contribute to the growth deficit in older children.

Technical considerations for fan-beam dual-energy x-ray absorptiometry body composition measurements in pediatric studies.

BACKGROUND: A piglet model was used to determine the influence of frequently encountered situations in clinical studies of infants and young children on fan-beam dual-energy x-ray absorptiometry (DXA) measurements. METHODS: DXA scans of piglets (640 g to 21,100 g) were acquired in the infant and adult mode and were analyzed with 1 infant, 1 pediatric, and 3 versions of adult software. RESULTS: The effect of repositioning of the piglets from the center to the periphery of the scanning table on DXA measurements included an average difference of up to 0.5% for total weight, 5.0% for bone mineral content, 5.6% for bone mineral density, 1.3% for lean mass, and 21.9% for fat mass (< or = .05, all comparisons) although no significant changes occurred when the piglets were scanned in symmetrical positions on either edge of the scanning table. Different posture (prone vs supine and side), varied number of blankets overlaid or wrapped around the piglet, and parenteral but not enteral bolus feeding could significantly alter fan-beam DXA measurements to varying extents. Adult and pediatric software underestimated bone area and bone mineral content but overestimated bone mineral density, lean mass, fat mass, and total weight compared with infant software measurements. However, strong predictive relationships among these fan-beam DXA data in subjects >10 kg allow systematic corrections of data from different scan modes and different software. CONCLUSIONS: Attention to details and consistency in the technique for scan acquisition and analysis are critical to the generation of meaningful data and to allow for detection of true differences in DXA measurements of small subjects.

Dual energy X-ray absorptiometry measurements in small subjects: conditions affecting clinical measurements.

OBJECTIVE: To document the clinical and experimental situations that may affect DXA measurements in small subjects. METHODS: 49 piglets (886g to 21100g) had measurements with either of two pencil beam densitometers (QDR 1000W and QDR 2000 Plus, Hologic Inc, Waltham, MA) using commercial infant (IWB) and adult whole body (AWB) software v5.71p and v5.71 respectively. AWB scans were analyzed with three additional software versions. 35 infants (2115 to 11564g) had IWB measurements. RESULTS: DXA measurements of total weight, bone mineral content, bone area, bone mineral density, fat and lean mass from IWB scans (all piglets) and from AWB scans (piglets >12 kg) were highly reproducible (p < 0.001). A statistically significant change occurred in at least one of the DXA measurements from the use of different platforms, variations in the amount and placement of covering (e.g., blanket), placement of the external calibration standard, presence of radiographic contrast material, presence of movement artifact, delivery of an intravenous fluid bolus prior to scanning or improper delineation of external calibration standard during analysis. Additionally, results varied amongst different versions of software as well as between IWB and AWB softwares. CONCLUSION: In small subjects, consistency in the DXA techniques is paramount for valid and meaningful comparison of DXA data in bone mass and body composition.

Validation of bone mass and body composition measurements in small subjects with pencil beam dual energy X-ray absorptiometry.

OBJECTIVE: To validate the most widely reported dual energy X-ray absorptiometry (DXA) technique for the measurement of bone mass and body composition in human infants with a piglet model. METHODS: Duplicate scans were obtained in 13 piglets (1950g to 21100g) using a whole body densitometer (Hologic QDR 2000 plus, Hologic Inc., Waltham, MA) operated in the pencil-beam mode on a two platform (aluminum platform overlying a foam table pad) system. DXA measurements that included total weight, bone mineral content, fat and lean mass were compared with carcass weight and chemical analysis for ash and calcium content, fat and lean mass. RESULTS: Measurements from duplicate DXA scans were nearly perfectly correlated (r = 0.98 to 1.00). DXA measurements were strongly predictive of scale weight and chemical composition for all piglets (adjusted r(2) = 0.93 to 1.00, intraclass reliability coefficients = 0.943 to 0.999, p < 0.001 for all comparisons) although DXA bone mineral content consistently underestimated carcass ash and calcium content. Measured values from heavier piglets were not significantly different from values predicted from the lighter piglets' data. Slopes from regression based on lighter versus heavier piglets were not significantly different except for the bone mineral content with carcass ash or calcium content. CONCLUSION: Our study validated the use of pencil beam DXA and its ability to determine relative changes in bone mass and body composition measurements over a much greater range of body weight than previous reports although its use as a direct indicator of nutrient requirement may be limited.

Bone and body composition measurements of small subjects: discrepancies from software for fan-beam dual energy X-ray absorptiometry.

OBJECTIVES: A piglet model was used to determine the variations in measurements from different software algorithms used in the same type of dual energy X ray absorptiometry (DXA) instruments from the same manufacturer. METHODS: Forty-one piglets (6190 +/- 5856g, mean +/- SD) were scanned in duplicate with a fan-beam densitometer (Hologic QDR4500A, Hologic Inc, Bedford, MA) in the infant whole body scan mode. The same scans were analyzed with two software versions: vKH6 (validated with carcass chemical measurement) and v11.2 (commercial software from the same densitometer manufacturer). RESULTS: All analysis values were highly correlated (r = 0.90 to 1.00) and DXA values for total weights were almost identical. However, v11.2 results consistently overestimated bone mineral content (49.3 +/- 23.4%, mean +/- SD), bone area (21.1 +/- 8.2%), bone mineral density (24.1 +/- 22.2%), and fat mass (160.9 +/- 71.7%) but underestimated lean mass (-14.3 +/- 5.5%) when compared to the values from vKH6. Differences between software versions increased with heavier piglets. CONCLUSION: The commercial software for fan-beam DXA measurement of piglets, matched for the size of human infants and young children, has major inaccuracies for bone mineral and body composition that become further exaggerated with increasing weight of the subject.

Body composition of neonates from fan beam dual energy X-ray absorptiometry measurement.

BACKGROUND: Fan beam dual energy x-ray absorptiometry (FB DXA) has recently been validated for the measurement of body composition in small subjects. This study represents the first report of body composition (bone mineral content, fat mass, and lean mass) in human neonates measured by FB DXA. METHODS: FB DXA measurements were performed in 73 healthy singleton neonates with mean +/- SD birth weights 3354 +/- 316 g (range, 2720 to 3982 g) and gestational ages 39.5 +/- 1.2 weeks (range, 37 to 42 weeks). There were 26 white (11 male infants, 15 female infants), 42 African American (17 male infants, 25 female infants), and 5 Hispanic (4 male infants, 1 female infant) infants. The predictive ability of physiologic parameters to predict body composition measurements was determined with regression analysis. RESULTS: The mean +/- SD for bone mineral content was 89.3 +/- 14.1 g, fat mass was 485 +/- 14.1 g, and lean mass was 2898 +/- 281.5 g. Weight was significantly correlated with all DXA measurements and was the single best predictor of body composition. Weight alone contributed 32% to 98% of the variance of the DXA measured parameters. Gender, race, and length were additional predictors that could be forced into a predictive equation for selected DXA dependent variables according to statistical significance. An independent gender effect was also demonstrated, with male infants having higher lean mass but lower fat mass. CONCLUSIONS: Our data in human neonates demonstrated the ability of FB DXA to measure body composition. Body weight is the best physiologic predictor of overall body composition. There is also an independent gender effect on soft tissue body composition.

Fan beam dual energy X-ray absorptiometry body composition measurements in piglets.

OBJECTIVES: A piglet model was used to validate and cross validate the fan-beam (FB) dual energy X-ray absorptiometry (DXA) software vKH6 and to determine the predictive values of physiologic parameters (weight, length, age and gender) on body composition. METHODS: Nineteen piglets (Group A: 600 to 21100 g) were used to validate the FB-DXA measurements of body composition based on chemical analysis of the carcass. An additional 22 piglets (Group B: 640 g to 17660 g) had FB-DXA measurements, and these values were compared to the predicted values generated from regression equations computed from group A piglets. Body composition for bone mass, lean mass and fat mass was based on ash weight, nitrogen and fat measured from three aliquots of homogenate from each carcass. Data from all piglets (n = 41) were used to determine the variations in body composition. Data analysis used regression, t test and analysis of variance. RESULTS: Duplicate DXA (total weight TW, bone mineral content BMC, bone area BA, bone mineral density BMD, lean mass LM and fat mass FM) measurements were highly correlated (r = 0.98 to 1.00, p < 0.001 for all comparisons) and were not significantly different. No significant differences were found in the residuals from predicted versus measured DXA values between the larger and the smaller (<1.6 kg) piglets from Group A. For Group B piglets, the DXA measured TW of 5666 +/- 5692 g (mean +/- SD), LM (5063 +/- 5048 g), FM (465 +/- 510 g), BMC (138 +/- 139 g), BA (486 +/- 365 cm(2)) and BMD (0.235 +/- 0.071 g/cm(2)) were highly significantly correlated with (r = 0.94 to 1.00, p < 0.001 for all comparisons) and were not significantly different from the predicted values. Data from all piglets (n = 41) showed that weight is the dominant predictor of whole body and regional body composition. Length, age or gender contributed to <2% of the variability of body composition. CONCLUSION: Body composition measurements using the FB DXA software vKH6 is highly reproducible. The software vKH6 is validated for use in a wide range of body weights and body composition, and cross-validated using a separate group of animals. Body weight is the dominant predictor of body composition in immature piglets.

Interchangeability of pencil-beam and fan-beam dual-energy X-ray absorptiometry measurements in piglets and infants.

BACKGROUND: Compared with the older pencil-beam (PB) dual-energy X-ray absorptiometry (DXA), the newer fan-beam (FB) DXA has the advantage of faster scan acquisition and greater accuracy of body-composition measurement in small subjects. However, no data exist on the relation between the measurements obtained with these techniques. OBJECTIVE: The objective of the study was to investigate whether PB and FB DXA measurements in small subjects are interchangeable. DESIGN: PB and FB DXA scans were performed on 26 piglets and 54 infants to examine the relation between the measurements obtained by using the 2 techniques. RESULTS: The correlation between all PB and FB DXA measurements of variables (total weight, bone area, bone mineral content, bone mineral density, and lean and fat masses) approached 1.0, but there were significant differences in absolute values. The extent of the differences varied according to the variable, with the lowest value for total weight (mean difference: approximately 1% for both piglets and infants) and the highest value for bone mineral content (mean difference: 35.3% and 36.7% for piglets and infants, respectively). PB and FB DXA measurements were strongly predictive of each other after adjustment (r(2) = 0.927-1.000 for the piglet data and 0.939-0.999 for the infant data). CONCLUSION: In small subjects, DXA measurements from PB and FB techniques were strongly predictive of each other, although their absolute values differed. Thus, group comparison of PB and FB DXA data is possible after adjustment of the data from either technique. It is advisable to generate normative data for each technique and to use the same technique throughout longitudinal studies.

Reduced bone mineralization in infants fed palm olein-containing formula: a randomized, double-blinded, prospective trial.

OBJECTIVE: Palm and palm olein (PO) oils are used in some infant formula fat blends to match the fatty acid profile of human milk, but their presence has been shown to lower calcium and fat absorption. We aimed to determine if the reported differences in calcium absorption could affect skeletal development by comparing bone mineral accretion in healthy term infants fed a milk-based formula with (PMF) or without PO. METHODS: Whole body bone mineralization was evaluated in healthy term infants fed 1 of 2 coded, commercially available, ready-to-feed infant formulas in a randomized, double-blind, parallel study. Subjects were fed either 1). PMF formula (Enfamil with iron; Mead Johnson Division of Bristol Myers, Evansville, IN; N = 63) containing PO/coconut/soy/high-oleic sunflower oils (45/20/20/15% oil); or 2). milk-based formula without PO (Similac with iron; Ross Products Division Abbott Laboratories, Columbus, OH; N = 65), containing high-oleic safflower/coconut/soy oils (40/30/30% oil) from enrollment by 2 weeks after birth until 6 months. Anthropometrics and formula intake were determined monthly; total body bone mineral content (BMC) and bone mineral density (BMD) were measured at baseline, 3, and 6 months of age using dual energy x-ray absorptiometry. RESULTS: Intent-to-treat analyses indicated no significant differences between feeding groups in weight, length, head circumference, or formula intake throughout the study. BMC and BMD were not different at baseline but repeated measures analyses show that infants fed PMF had significantly lower BMC and BMD at 3 and 6 months. CONCLUSIONS: Healthy term infants fed a formula containing PO as the predominant oil in the fat blend had significantly lower BMC and BMD than those fed a formula without PO. The inclusion of PO in infant formula at levels needed to provide a fatty acid profile similar to that of human milk leads to lower bone mineralization.

Phantoms for cross-calibration of dual energy X-ray absorptiometry measurements in infants.

OBJECTIVE: To test the suitability of phantoms to cross-calibrate body composition measurements in small subjects among different dual energy X-ray absorptiometry (DXA) instruments. METHODS: A set of four phantoms with total weights 1520g, 3140g, 4650g and 7490g were made with low cost and easily available materials. Each phantom was made from assembling polyethylene bottles (100 to 1000 mL) filled with either pure olive oil or electrolyte solution in different combinations, and borosilicate tubes (3 and 5 mL) and flexible polypropylene tubing filled with calcium carbonate. Triplicate measurements of each of the four phantoms were performed with three pencil beam densitometers made by the same manufacturer (Hologic Inc., Waltham, MA): two QDR 2000 (University of Liege, Liege, Belgium, and Wayne State University, Detroit, Michigan) and a QDR1500 (University Children's Hospital, Greifswald, Germany) using infant whole body-scanning mode and analyzed with software V5.73P. RESULTS: DXA measured total weight, or bone, lean and fat masses, from one center were highly predictive of DXA measurements from the other centers with an adjusted r2 of 0.94 to 1.00, p < 0.001. This was the case whether the measurements from single scan or from average of triplicate scans were used in the analysis. CONCLUSIONS: Systematic corrections, in the form of linear transformations, are possible to allow comparison of clinical data generated from different centers. Different size phantoms can be made to accommodate the varying range of weights and body composition of study subjects.

Use of fan beam dual energy x-ray absorptiometry to measure body composition of piglets.

A piglet model was used to determine whether the fan beam dual energy X-ray absorptiometry technique (DXA) could be adapted for the measurement of body composition of small subjects. Commercial domestic swine piglets (n = 14) with weights between 1.95 and 21.1 kg had duplicate fan beam-DXA scans followed by chemical analysis of body composition. Each scan required 2-3 min to complete. DXA-measured total body weight was validated against scale weights of the piglets (with and without blanket and other covering), DXA bone mineral content validated against carcass ash and calcium, and DXA lean and fat mass validated against chemical lean and fat contents. Measurements from duplicate DXA scans were highly reproducible with adjusted r(2) values from 0.992 to 1.000. Each DXA measurement was highly predictive of the scale weight or specific chemical body composition with adjusted r(2) values from 0.974 to 0.999. The intraclass reliability coefficient among measurements from individual scans with scale weight or the weight of individual chemical components was extremely high at > or =0.99 for all comparisons. The SD of residuals for DXA prediction of scale weights (with and without covering) were 168 and 157 g, respectively, and were 27, 8.8, 122 and 72 g for the prediction of carcass ash, calcium, lean and fat tissue content, respectively. We conclude that rapid scan acquisition, accurate and precise prediction of scale weight and components of body composition would support the use of fan beam-DXA for body composition studies in growing humans or animals.

Lumbar spine bone measurements in infants: whole-body vs lumbar spine dual X-ray absorptiometry scans.

Availability of software delineation of the lumbar spine region from infant whole-body (IWB) dual energy X-ray absorptiometry scan offers an opportunity to gain additional information at the lumbar spine without a separate scan, although the validity of this technique has never been tested. Lumbar spine measurements derived from IWB scans using software-delineated first to fourth lumbar vertebrae, and from specific infant spine (IS) scans, were determined in 111 infants using two pencil-beam densitometers. Intraoperator repeatability determined by reanalysis of 10 pairs of IWB and IS scans from each densitometer. Lumbar spine area, bone mineral content, and bone mineral density from IWB and IS scans were significantly correlated r = 0.68-0.95, p < 0.001 for all comparisons) but show poor agreement (Bland-Altman method) with one SD of the differences equal to 26-55% of the mean. Intraoperator reanalysis shows good agreement with one SD of the differences from IWB scans at <7% of the mean, and <2.9% from IS scans. Findings were the same for both densitometers. We conclude that lumbar spine bone measurements from IWB or IS scans are highly reproducible and significantly correlated but data from IWB scans cannot substitute for data from IS scans.