Quantitative ultrasound and dual-energy x ray absorptiometry in bone status assessment of ex-preterm infants

Comparison of quantitative ultrasonography and dual X-ray absorptiometry for bone status assessment in South African children living with HIV

Children living with HIV (CLHIV) have decreased bone mineral content (BMC) and density (BMD), increasing risk for fracture and future osteoporosis. While DXA is the gold-standard for bone assessments, it lacks availability in resource-constrained settings (RCS). Quantitative ultrasound (QUS) offers an alternative owing to its portability, low cost, ease of handling, and lack of ionizing radiation. While QUS has detected reduced bone quality in CLHIV, the relationship between QUS and DXA in this population remains unexplored. At baseline and 12 months, BMC and BMD of the whole body, lumbar spine, and radius were measured by DXA in a longitudinal cohort of CLHIV in Johannesburg, South Africa. Calcaneal speed of sound (SOS) and broadband ultrasound attenuation (BUA) and radius SOS were obtained by QUS, and calcaneal stiffness index (SI) was calculated. Spearman correlations, with and without HIV stratification, were performed between QUS and DXA measurements at each visit and for absolute difference in measurements between visits. At baseline and 12-months, calcaneal BUA and SI displayed strong positive correlations with DXA, with only modest correlations between radial QUS and DXA at baseline. Longitudinal measures of QUS did not correlate with DXA. At both baseline and 12-months, individuals with DXA whole-body BMD z-score < -1 displayed significantly lower calcaneal BUA and SI. Cross-sectionally, calcaneal QUS correlates strongly with whole body DXA and may represent a viable diagnostic alternative in RCS. Longitudinally, the two methods do not correlate well, possibly reflecting that each method assesses distinct aspects of bone architecture.

Evaluation of bone mineralization in former preterm born children: Phalangeal quantitative ultrasound cannot replace dual-energy X-ray absorptiometry

Background

Preterm infants are at risk of impaired bone health in later life. Dual-energy X-ray absorptiometry-scan (DXA) is the gold standard to determine bone mineralization. Phalangeal quantitative ultrasound (pQUS) is an alternative technique that is inexpensive, easy to use and radiation-free. The aim of this study was to investigate whether both techniques reveal equivalent results.

Materials and methods

Sixty former preterm infants (31 boys; 29 girls) received a DXA and pQUS at age 9 to 10 years. DXA measured bone mineral content (BMC) and bone mineral density (BMD) for total body and lumbar spine (L1-4), while pQUS measured the amplitude dependent speed of sound (AD-SoS) and bone transit time (BTT) at metacarpals II-IV providing continuous values and Z-scores based on age and sex. Four statistical methods evaluated the association between both techniques: Pearson's correlation coefficients, partial correlation coefficients adjusted for gestational age, height and BMI, Bland-Altman analysis and cross tabulation.

Results

Both techniques showed a statistically significant weak correlation for continuous values as well as Z-scores (0.291–0.462, p < 0.05). Boys had significant and relatively high correlations (0.468–0.585, p < 0.05). In comparison, the correlations for girls were not significant. Correlation coefficients further decreased while calculating the partial correlations. The Bland-Altman plots showed poor agreement. Sensitivity ranged from 33% to 92% and specificity from 16% to 68%. Positive and negative predictive values ranged from 4% to 38% and 82% to 97%, respectively.

Conclusions

We found statistically significant weak correlations and poor agreement between DXA and pQUS measurements. DXA is not equivalent to pQUS and therefore not replaceable by this technique in former preterm born children at the age of 9 to 10 years.

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DXA is the golden standard to determine bone mineralization, while Quantitative ultrasound is a radiation-free alternative.

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Four statistical tests were used to investigate the equivalence of both methods.

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Comparison of results of 60 preterm born children at age 9 to 10 years found poor agreement between both methods.

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There was a discrepancy in differentiating the same children with normal or reduced bone mineralization.

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Quantitative ultrasound cannot replace the DXA scan for determination of bone mineralization in preterm born children.

Evidence-based outcomes on diagnostic accuracy of quantitative ultrasound for assessment of pediatric osteoporosis - a systematic review

BACKGROUND

Dual-energy absorptiometry (DXA) is the current reference standard for assessing pediatric osteoporosis; however due to its areal nature, it has limitations. Thus, quantitative ultrasound (QUS), a modality free of ionizing radiation, has been proposed as a potential surrogate for DXA.

OBJECTIVE

To semi-quantitatively assess the diagnostic accuracy of QUS for evaluating pediatric osteoporosis according to the U.S. Preventive Services Task Force guidelines.

MATERIALS AND METHODS

We retrieved articles on the diagnostic accuracy of quantitative US for assessing abnormal bone quality or quantity in patients of mean age ≤19 years from MEDLINE, EMBASE and Cochrane Library CCTR databases. Evidences were analyzed for reliability, construct and criterion validity, and responsiveness of quantitative US, according to the following questions: (1) How reliable is the acquisition of QUS measurements? (2) Is QUS diagnostically accurate to characterize bone strength and quality in osteoporotic children? (3) Is QUS sensitive to detect changes in bone status over time? (4) Is QUS able to predict future skeletal fractures/degeneration? Three reviewers independently evaluated the quality of reporting and methodological quality using the Standards for Reporting of Diagnostic Accuracy (STARD) and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tools.

RESULTS

Out of 262 retrieved references (215 unique), we included 28 studies (1,963 patients; 807 reported boys and 761 girls, others unspecified; reported mean age, 0-19 years). The mean quality of reporting score was "excellent" in 24/28 (86%) studies; 11/28 (39%) studies had "adequate" research design quality.

CONCLUSION

There is no evidence of the diagnostic value of QUS at the present time despite the overall excellent and adequate research design quality of primary studies. Although QUS can produce reliable measurements, insufficient evidence has been reported to support other clinimetric properties of this technique.

Bone status and associated factors measured by quantitative ultrasound in preterm and full-term newborn infants

BACKGROUND

A clear understanding of the factors associated with bone status in newborn infants is essential for devising strategies for preventing osteoporotic fracture in future generations.

OBJECTIVE

The aims of this study were to perform bone speed of sound (SOS) to assess the status of the tibia in preterm and full-term newborns, and to evaluate factors associated with bone status at birth.

STUDY DESIGNS

Bone SOS was measured by quantitative ultrasonography on the left tibia in full-term and preterm newborn infants immediately after birth. A birth chart and maternal history were recorded. Univariate and multivariate analyses were performed to identify factors affecting bone SOS at birth.

SUBJECTS

The study analyzed 667 infants, including 370 males and 297 females, during study period.

RESULTS

Univariate analysis revealed that gender, gestational age (GA) and birth anthropometrics significantly affected tibial bone SOS at birth whereas maternal factors did not. Multivariate multiple regression analysis revealed that gender (male-to-female coefficient of 45.71 and 32.52 in premature and full-term infants, respectively), GA (coefficient of 32.55 and 31.27 in premature and full-term infants, respectively, for every 1-week increase), and birth weight (coefficient of -0.11 and -0.103 in premature and full-term infants, respectively, for every 1-gram increase) were important factors affecting tibial bone SOS in both preterm and full-term newborn infants at birth.

CONCLUSIONS

Male gender and advanced GA have a positive effect on increasing tibial bone SOS at birth, while birth weight had a negative effect on increasing tibial bone SOS. Tibial bone SOS is higher in small-for-gestational-age infants than in those of appropriate-for-gestational-age infants.

The role of antenatal factors on tibial speed of sound values in newborn infants

OBJECTIVE

To evaluate the role of some antenatal factors on bone status of newborn infants.

METHODS

Tibial bone speed of sound (SOS) value was measured by quantitative ultrasound within 5 days after birth in 205 neonates whose gestational ages ranged between 31 and 40 weeks. The cohort was divided into two groups according to intrauterine growth curves, as small- (SGA) and appropriate-for-gestational age (AGA). All cases were also been evaluated by antenatal ultrasonography for oligohydroamniosis.

RESULTS

The mean SOS value was found significantly higher in SGA (n = 43) than AGA infants (n = 162) (p < 0.001). The mean tibial SOS value of infants with a history of oligohydroamniosis (n = 28) was also higher than those without oligohydroamniosis (n = 177) (p < 0.001). But, in SGA infants with a history of oligohydroamniosis (n = 17), the mean tibial SOS value was similar to those SGA infants without oligohydroamniosis (n = 26) (p > 0.05). Infants whose mothers had smoked during pregnancy (n = 18) had significantly higher tibial SOS values compared to those of whose mothers had not (n = 187) (p = 0.006). In addition, mean tibial SOS values were determined higher in male infants (n = 116) compared to female infants (n = 89) (p = 0.036). There was a significant correlation between tibial SOS values and gestational age (r = 0.178, p = 0.011).

CONCLUSIONS

While creating reference curves of SOS values at birth, smallness for gestational age, maternal smoking and gender as well as gestational age should be taken into account.

Early high calcium and phosphorus intake by parenteral nutrition prevents short-term bone strength decline in preterm infants

BACKGROUND AND AIM

Very premature newborns have an increased risk of low bone mass and metabolic bone disease. Most longitudinal studies report a significant decline in bone strength in the first weeks after birth. The aim of the study was to evaluate whether higher early calcium (Ca) and phosphorus (P) intake delivered by parenteral nutrition (PN) can prevent bone strength decline in preterm infants, within the first weeks after birth.

PATIENTS AND METHODS

This was a randomized controlled trial of consecutively admitted neonates born with ≤ 33 weeks of gestational age, assigned to receive either Ca 45 mg · kg⁻¹ · day⁻¹ (low dose [LD]) or Ca 75 mg · kg⁻¹ · day⁻¹ (high dose [HD]) by PN. P was added to the PN solutions at a fixed Ca:P ratio (mg) of 1.7:1. Bone strength was assessed by the speed of sound (SOS) using the quantitative ultrasound method. Measurements were performed weekly from birth until discharge. Low bone strength (SOS < 10th centile of reference values) was the main outcome.

RESULTS

Eighty-six infants were enrolled, 40 assigned to LD group and 46 to HD group. Mean (standard error) gestational age was 29.6 weeks (2.1) and birth weight was 1262 g (0.356). In the HD group, the SOS values never fell below those recorded at birth and, up to the sixth week of life, low bone strength was significantly less frequent as compared with that in the LD group, in spite of progressive reduction in parenteral mineral intake and/or establishment of full enteral feeding.

CONCLUSIONS

Early assigned parenteral intake of Ca 75 mg · kg⁻¹ · day⁻¹ and P 44 mg · kg⁻¹ · day⁻¹ significantly contributed to preventing short-term bone strength decline in preterm infants.

Body composition and its components in preterm and term newborns: A cross-sectional, multimodal investigation

A prospective, cross-sectional, observational study in preterm and term infants was performed to compare multimodal measurements of body composition, namely, limb ultrasound, bone quantitative ultrasound, and dual X-ray absorptiometry (DXA). One hundred and two preterm and term infants appropriate for gestational age were enrolled from the newborn nursery and neonatal intensive care unit. Infants were included when they were medically stable, in an open crib, on full enteral feeds and within 1 week of anticipated discharge. Correlations among the various measurements of body composition were performed using standard techniques. A comparison between preterm infant (born at 28-32 weeks) reaching term to term-born infants was performed. Limb ultrasound estimates of cross-sectional areas of lean and fat tissue in a region of tissue (i.e., the leg) were remarkably correlated with regional and whole-body estimates of fat-free mass and fat obtained from DXA suggesting the potential usefulness of muscle ultrasound as an investigative tool for studying aspects of body composition in this fragile population. There was a weak but significant correlation between quantitative ultrasound measurements of bone strength and DXA-derived bone mineral density (BMD). Preterm infants reaching term had significantly lower body weight, length, head circumference, muscle and fat cross-sectional area, bone speed of sound, whole-body and regional lean body mass, fat mass, and BMD compared to term-born infants. Current postnatal care and nutritional support in preterm infants is still unable to match the in-utero environment for optimal growth and bone development. The use of relatively simple bedside, noninvasive body composition measurements may assist in understanding how changes in different components of body composition early in life affect later growth and development.

Changes in quantitative ultrasound in infants born at less than 32 weeks' gestation over the first 2 years of life: influence of clinical and biochemical changes

Studies in preterm infants show reduced speed of sound (SOS) as measured by quantitative ultrasound (QUS) during the immediate neonatal period. There is a scarcity of data on SOS changes following hospital discharge. The aim of this study was to assess SOS over the first 2 years in preterm infants. Infants were recruited from a neonatal follow-up clinic. Tibial QUS was performed using the Omnisense 7000P scanner. Thirty-nine infants born at <32 weeks' gestation had a single SOS measurement (median 3,203 m/second, range 2,609-3,495) which correlated with corrected gestational age (CGA) (r = 0.8, P < 0.005). The majority of measurements were within the manufacturer's reference range for term infants. SOS standard deviation score (SDS) in infants aged 0-6 months CGA demonstrated a negative correlation with duration of total parenteral nutrition (r = 0.7, P < 0.05) and a positive correlation with serum phosphate (r = 0.6, P < 0.05.) Two groups of infants had serial measurements: eight had measurements performed at term CGA and early infancy (early) and seven had measurements in later infancy (late). In the early group SOS SDS increased (P < 0.005), and the greatest increase in SOS over time occurred in infants with the lowest SOS at term (r = 0.9). In the late group there was no significant change over time. SOS SDS change did not show any correlation to weight SDS change. Catch-up in SOS occurs postterm in most infants by 6 months and is independent of postnatal growth. Infants with the lowest SOS at term have the fastest rate of catch-up. The opportunity for catch-up may be greatest in early infancy.