Quantitative Ultrasound Measurements at Hand Phalanges in Children and Adolescents: A Longitudinal Study

Abtract

The purpose of this longitudinal study was to characterize changes in quantitative ultrasound (QUS) values over a 1-y period in healthy boys and girls aged 7 to 12 y at baseline and assess the relation between the increase in anthropometric parameters and amplitude dependent speed of sound (Ad-SoS). A total of 269 children completed the study (139 girls and 130 boys). Ultrasound measurements were performed with a DBM Sonic 1200 device (IGEA, Carpi, Italy), which measures the Ad-SoS, m/s. Girls had significantly higher QUS values than boys at first and second measurements (p < 0.01 and p < 0.00001, respectively). Both girls and boys experienced statistically significant increases in Ad-SoS and all anthropometric parameters over a 1-y period. When the studied group was divided into age groups by year, the differences in QUS values between genders were significant only for 11 and 12 y groups at baseline (p < 0.02 and p < 0.01, respectively) and second visit (p < 0.00001 and p < 0.001, respectively). Stepwise regression analyses models with Ad-SoS at baseline and after 1 y as dependent variables showed a strong correlation between Ad-SoS and Tanner stage in girls but not in boys. In the entire survey group, only 21.5% of the boys and 41% of the girls experienced increases in Ad-SoS more than least significant change. This article suggests that QUS measurements allow the investigation of longitudinal changes and give reliable information about skeletal status in a manner similar to other methods. (E-mail: [email protected])

Introduction

Although dual energy x-ray absorptiometry (DXA) is the method considered to be the gold standard in pediatrics, we must keep the disadvantages of this method in mind while trying to develop other more effective diagnostic tools used in the pediatric population. DXA has some essential limitations. First, DXA estimates only the level up to which a radiation beam is attenuated by bone tissue that depends not only on physical density, but on bone size as well. It means that a smaller bone may have a lower areal bone density than a larger bone (Nelson and Koo 1999, Prentice et al 1994, Rauch and Schoenau 2002). Because of increases in bone size, not volumetric density, the changes in bone size during growth make the value of DXA less useful as an assessment tool in children than in adults. Second, DXA does not provide information about the quality of bone.

In recent years, the method of quantitative ultrasound (QUS) has been developed for assessing bone properties. Low-frequency ultrasound travels across bone with a velocity that is related to bone quality and density. Therefore, it seems QUS techniques may be less influenced by bone size (Falk et al. 2003). Furthermore, QUS can reveal physical properties of bone determined by bone composition and by structure (Njeh et al. 1997). QUS is also void of ionizing radiation, cost-effective, easy to use and portable so its features are beneficial in pediatrics. QUS systems exist for measurements at various skeletal sites such as calcaneus, phalanges, tibia and patella. Phalangeal QUS measurements have shown the ability to reveal changes due to skeletal growth (Halaba and Pluskiewicz 1997), aging (Ventura et al 1996, Grampp et al 1997) and diseases (Takada et al 1997, Guglielmi et al 1999). These assets caused many pediatricians to carry out some cross-sectional normal ranges for children and adolescents by means of a DBM Sonic 1200 machine (IGEA, Carpi, Italy) (Halaba and Pluskiewicz 1997, Halaba and Pluskiewicz 2004, Wuster et al 2000, Baroncelli et al 2001, Barkmann et al 2002). Large child and adolescent populations from different European countries were measured and trends of changes in measured ultrasound parameter during childhood and puberty were comparable as shown in studies using DXA measurements (Bonjour et al 1991, Theintz et al 1992). Further, some studies were performed in young subjects with different diseases known to affect bone metabolism. In case-control studies, QUS proved its utility in the detection of skeletal changes in subjects with genetic disorders (Pluskiewicz et al. 2003a), renal osteodystrophy (Pluskiewicz et al 2002a, Pluskiewicz et al 2003b), acute lymphoblastic leucaemia (Pluskiewicz et al. 2002b) and in subjects treated by gonadotrophin-releasing hormone (Kapteijns-van Kordelaar et al. 2003). There are also some longitudinal studies in healthy children and adolescents (Lappe et al 2000, Vignolo et al 2006) and in survivors of malignant bone tumors (Azcona et al. 2003) and acute lymphoblastic leucaemia (Pluskiewicz et al. 2004), in subjects with renal insufficiency (Pluskiewicz et al. 2005) and in subjects with genetic disorders (Halaba et al. 2006). Recently, phalangeal QUS and DXA measurements were compared in healthy subjects (Halaba et al. 2005) and have shown that QUS has the potential to express bone changes in measurements comparable to DXA.

The purpose of the current longitudinal study was to characterize changes in QUS values over a 1-y period in healthy boys and girls aged 7 to 12 y at baseline. Furthermore, the relationship between the increase in anthropometric parameters and Ad-SoS was assessed. The second aim of the study was to establish the follow-up reference curves for children and adolescents aged 7 to 12 y. Intensive treatment in many diseases (corticosteroids, citotoxic agents, radiotherapy) may influence bone metabolism and skeletal growth. There is a need to monitor these changes longitudinally and we, therefore, should compare results with data obtained in a normal healthy population.