Joseph C. H. Wong

Bone mineral density in Australian children, adolescents and adults with cystic fibrosis: a controlled cross sectional study

Background: Low bone mineral density (BMD) is recognised in individuals with cystic fibrosis (CF) although the pathogenesis remains unclear. The aims of this study were to compare BMD over a broad continuum of Australian individuals with CF with healthy controls and to examine the relationship between BMD and clinical parameters including physical activity, nutrition, and vitamin D levels. Methods: BMD of the lumbar spine (LS), total body (TB), femoral neck (FN), cortical wrist (R33%), and distal wrist (RUD) was examined in 153 individuals with CF aged 5.3–55.8 years (84 males) and in 149 local controls aged 5.6–48.3 years (66 males) using dual energy x ray absorptiometry. Anthropometric variables, body cell mass, markers of disease severity, corticosteroid usage, measures of physical activity, dietary calcium and caloric intake and serum vitamin D were assessed and related to BMD. Results: Compared with controls, mean BMD was not significantly different in children aged 5–10 years with CF. Adolescents (females 11–18 years, males 11–20 years) had reduced TB and R33% BMD when adjusted for age, sex, and height (difference in BMD (g/cm2) adjusted means between control and CF: TB = 0.04 (95% CI 0.01 to 0.07); R33% = 0.03 (95% CI 0.01 to 0.06)). BMD was reduced at all sites except R33% in adults (difference in BMD (g/cm2) adjusted means between control and CF: TB = 0.05 (95% CI 0.02 to 0.09); LS = 0.08 (95% CI 0.03 to 0.14); FN = 0.09 (95% CI 0.03 to 0.15); RUD = 0.03 (95% CI 0.01 to 0.05)). In children/adolescents BMD was weakly associated with nutritional status and disease severity. Conclusions: BMD was normal in a well nourished group of prepubertal children with CF. A BMD deficit appears to evolve during adolescence and becomes more marked in adults. Individuals with CF should optimise nutrition, partake in physical activity, and maximise lung health in order to optimise BMD. Further longitudinal studies are required to understand the evolution of reduced BMD in young people and adults with CF.

Controlled longitudinal study of bone mass accrual in children and adolescents with cystic fibrosis

Background: A study was undertaken to observe the gains in bone mass in children and adolescents with cystic fibrosis (CF) over 24 months and to examine the relationship between areal bone mineral density (aBMD) and associated clinical parameters including physical activity, nutrition, and 25-hydroxyvitamin D (25OHD). Methods: Areal BMD of the total body (TB), lumbar spine (LS), and total femoral neck (FNt) were repeatedly measured in 85 subjects aged 5–18 years with CF and 100 age and sex matched controls over 2 years. At each visit anthropometric variables, nutritional parameters, pubertal status, disease severity, physical activity, dietary calcium, caloric intake, and serum 25OHD were assessed and related to aBMD. Results: After adjusting for age, sex, and height Z-score, gains in LS aBMD in children (5–10 years) and TB and FNt aBMD in adolescents (11–18 years) with CF were significantly less than in controls. Lean tissue mass was significantly associated with TB and LS aBMD gains in children and adolescents and explained a significant proportion of the aBMD deficit observed. Lung function parameters were significantly associated with aBMD gains in adolescents with CF. Conclusions: Inadequate bone mass accrual during childhood and adolescence contributes to the low bone mass observed in adults with CF. Accounting for the height discrepancy which is frequently observed in those with CF, in addition to age and sex, is important when assessing low bone mass in children and adolescents with CF. To optimise an individual’s potential to acquire maximal bone mass, it is necessary to maximise nutritional status and limit the progression of chronic suppurative lung disease.

Service quality measurement in a medical imaging department

This project evaluates the quality of service provided for ambulatory clients at the Bone Densitometry Unit in the Royal Brisbane Hospital using the Servqual instrument. Every adult outpatient visiting the Bone Densitometry Unit over a six‐month period was invited to participate in the survey. On each of the five measured dimensions of service quality: tangibles, reliability, responsiveness, assurance and empathy, there were high satisfaction ratings with both perception scores and expectation‐minus‐perception gap scores. Of the five dimensions, responsiveness, assurance and empathy factors were more important predictors of overall service satisfaction. Perception scores better predict overall satisfaction than gap scores. Therefore, Servqual is useful if knowledge of the pattern of expectation trends is important in managerial decision making. Otherwise, the measurement of perception scores appears sufficient to assess service quality for ambulatory clients in a medical imaging department.

Evaluation of the limits of visual detection of image misregistration in a brain fluorine-18 fluorodeoxyglucose PET-MRI study

In routine clinical work, registration accuracy is assessed by visual inspection. However, the accuracy of visual assessment of registration has not been evaluated. This study establishes the limits of visual detection of misregistration in a registered brain fluorine-18 fluorodeoxyglucose positron emission tomography to magnetic resonance image volume. The “best” registered image volume was obtained by automatic registration using mutual information optimization. Translational movements by 1 mm, 2 mm, 3 mm and 4 mm, and rotational movements by 1°, 2°, 3° and 4° in the positive and negative directions in the x- (lateral), y- (anterior-posterior) and z- (axial) axes were introduced to this standard. These 48 images plus six “best” registered images were presented in random sequence to five observers for visual categorization of registration accuracy. No observer detected a definite misregistration in the “best” registered image. Evaluation for inter-observer variation using observer pairings showed a high percentage of agreement in assigned categories for both translational and rotational misregistrations. Assessment of the limits of detection of misregistration showed that a 2-mm translational misregistration was detectable by all observers in the x- and y-axes and 3-mm translational misregistration in the z-axis. With rotational misregistrations, rotation around the z-axis was detectable by all at 2° rotation whereas rotation around the y-axis was detected at 3–4°. Rotation around the x-axis was not symmetric with a positive rotation being identified at 2° whereas negative rotation was detected by all only at 4°. Therefore, visual analysis appears to be a sensitive and practical means to assess image misregistration accuracy. The awareness of the limits of visual detection of misregistration will lead to increase care when evaluating registration quality in both research and clinical settings.

Bone mineral density in adolescent females with recently diagnosed anorexia nervosa

UNLABELLED Anorexia nervosa (AN) can lead to osteoporosis and fractures. OBJECTIVE This study evaluated adolescent females with AN diagnosed within the previous 12 months to determine whether there is bone mass reduction and to investigate relationships between nutritional indices (weight, body mass index [BMI], lean mass, fat mass, and percentage fat) and total body (TB) and lumbar spine (LS) bone mineral densities (BMD) and content (BMC). METHOD TB and LS BMD and BMC and body composition were measured in 24 adolescent females with AN. RESULTS There was no significant reduction in TB or LS BMD. Regression analysis shows significant correlation (p < 0.001) between lean mass and TB BMD (r = +0.83), TB BMC (r = +0.92), LS BMD (r = +0.81), and LS BMC (r = +0.92). There was also a significant relationship between weight percentile and LS BMD z score (p < 0.005; r = +0.60). DISCUSSION Adolescent females with early AN do not appear to have reduced bone mass. Lean mass is correlated to BMD and BMC.

Pubertal development and its influences on bone mineral density in Australian children and adolescents with cystic fibrosis

Background:  Pubertal delay is thought to contribute to suboptimal peak bone mass acquisition in young people with cystic fibrosis (CF), leading to an increased fracture incidence. This study aims to compare pubertal development in young people with CF with that of a local healthy population and assess the influence it has on areal bone mineral density (aBMD).

The use of air displacement plethysmography in children and adolescents with cystic fibrosis

Objectives: The purpose of this paper was to evaluate the use of air displacement plethysmography (ADP) in children and adolescents with cystic fibrosis (CF). Specifically, the primary aim of this study was to compare estimates of fat-free mass (FFM) measured from ADP and dual energy X-ray absorptiometry (DEXA) in children and adolescents with CF. The secondary aim was to compare the effect of using predicted thoracic gas volume (V TG) and measured V TG for the calculation of FFM by ADP in this population.Methods: Cross-sectional FFM measurements were taken using ADP and DEXA in 52 children and adolescents with CF, ranging in age from 6.3 to 16.6 y.Results: Bland–Altman analysis showed that ADP values of FFM were on average 0.59 kg higher than DEXA values (95% limits of agreement = 3.61 to −2.43 kg); however this difference was not significant. There was no significant correlation (r=−0.26, P=0.07) between the mean FFM and difference in FFM between ADP and DEXA. Using either predicted or measured V TG did not significantly affect FFM estimates in individuals with CF who had normal lung function (bias=−0.39±0.86 kg; r=−0.02, P=0.93).Conclusions: ADP is an appropriate technique for use in children and adolescents with CF.

Evaluation of Femur Angle Abduction/Adduction and Bone Mineral Density Values

Bone densitometry using fan-beam technology allows both femurs to be rapidly measured with the aid of a bilateral foot-positioning tool to keep both legs in internal rotation. The Lunar Prodigy system uses a bilateral foot-positioning tool with a fixed interpedal width. The aim of this study was to determine whether the small degrees of femur abduction and adduction introduced by a fixed interpedal width-positioning tool influences the femur bone mineral density (BMD) measurements. Two-hundred patients had the total femur (FTot), femoral neck (FN), femoral shaft (FS), and femoral trochanter (FT) BMD, and angles of femoral abduction and adduction measured. Of all subjects, 26.5% had an absolute difference in femur angulation of 1 degrees , 77.5% had 5 degrees and 97% had 10 degrees. There was no significant correlation between the right-to-left differences in femur angles and the absolute right-to-left differences in FTot, FN, FS, and FT BMD. The introduction of small degrees of femur angulation with the fixed interpedal width bilateral foot positioner does not significantly affect the measured BMD at the various femur regions.

An unusual site of heterotopic calcification

Heterotopic calcification may occur following paralysis from spinal cord injury, most commonly affecting the hips. This case demonstrates a bone scan on a T5 paraplegic patient showing an unusual site of heterotopic calcification in the paravertebral musculature in addition to the hip regions. Subsequent CT scanning confirmed the presence of calcification in the erector spinae musculature.

Towards validation of use of an Australian reference database for the diagnosis of osteoporosis with DXA

Introduction: Bone densitometry in Australia uses the data from the Geelong Osteoporosis Study for conversion of bone mineral density (BMD) to T‐scores to diagnose osteoporosis based on the World Health Organization (WHO) classification criteria. An underlying assumption is that the bone status of women in Geelong city is representative of the rest of Australia. The aim of this study is to compare the prevalence of normal BMD, osteopenia and osteoporosis of sample Brisbane women to Geelong, and to assess the validity of the Geelong reference database for Australia‐wide application.