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Biomedical subjects

J G Truscott

Publications and source records attributed to J G Truscott.

34 records · Page 2Linked to original sources
PubMed1996

A portable system for measuring bone mineral density in the pre-term neonatal forearm.

Current systems used to measure bone mineral content (BMC) in the neonate have the major drawback that the child must be well enough to be moved to the scanner. Consequently, low birth weight pre-term neonates, a group at particular risk of mineral compromise, cannot be measured. This paper describes a portable neonatal bone mineral device capable of measuring bone mineral in the incubator. It uses a radiation sensitive, charge coupled device (CCD) to acquire a bone mineral image enabling bone mineral to be measured at various sites. It measures bone mineral density (BMD) with a precision of 5.5 mg cm-2 in vivo, reduced to 7.5 mg cm-2 when repositioning between scans is taken into account. The procedure takes under 5 min with an image acquisition time of 30 s and an absorbed radiation dose to skin of 6 microSv. Calibration has been undertaken with aluminium foils of differing thickness to confirm the linearity of the system throughout the intended measurement range. A regression line fitted to the data demonstrated linearity and correlation between BMD and aluminium thickness with r = 0.99 (p < 0.0001). Preliminary measurements on pre-term neonates show values of BMD ranging from 43 to 115 mg cm-2 in babies aged 23-41 weeks post-conception. These figures are within the linear range of the system.

Absorptiometry, Photon↗
PubMed1996

Spatial distribution of femoral bone mineral in dual energy X-ray absorptiometry images: a possible technique to improve discrimination between normal and osteoporotic patients.

The measurement of bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) provides an indicator of subsequent risk of hip fracture, but because of the significant overlap of measurements obtained from osteoporotic and control groups its predictive power is limited. The radiographic technique of Singh grading for the assessment of femoral osteoporosis utilizes information about the distribution of trabecular bundles, but the morphological information available in the DXA image has not previously been analysed. In this study of DXA images from 64 individuals (32 controls and 32 classified as osteoporotic) a subjective grading technique analogous to Singh grading is proposed, and quantitative measurements are made of image features corresponding to two of the categories. Discrimination was assessed using receiver operating characteristic (ROC) curves: the best discrimination was by spinal BMD (Az = 0.85 +/- 0.05) a performance equalled by one of the new parameters; the subjective grading method (Az = 0.79 +/- 0.07) performed as well as measurements of BMD in the femur. These results suggest that although the alternative measures do not improve on the discrimination possible using spinal BMD, morphological information from the hip itself may in the future have a place in the assessment of bone quality.

Absorptiometry, Photon↗
PubMed1994

A phantom for quantitative ultrasound of trabecular bone.

The propagation mechanisms of ultrasound in trabecular bone are poorly understood and have been the subject of extended debate; also, the reproducibility of ultrasonic measurements on bone in vivo using commercial ultrasound heel-scanning devices is such that the interpretation of the obtained data is difficult. In this paper we describe recent developments in the production of a bone-mimicking material which is well suited to the task of routine monitoring of commercial ultrasound bone scanners. The material, based on a standard epoxy resin is fabricated to a pre-determined porosity value by the inclusion of a marrow-mimicking material thereby introducing a known and controlled mean pore size. Measurements of the velocity and attenuation of the material have been performed over a range of porosity values from 10% to 80% in the frequency range 500-900 kHz; also, broadband ultrasonic attenuation (BUA) values have been obtained from commercial equipment. The material displays velocities in the range 1844-3118 m s(-1) and attenuation ranging from 7.0 to 17.7 dB cm(-1) at 500 kHz.

Biomimetic Materials↗
PubMed1993

Bone mineralisation, body fat and anthropometric measurement in mothers delivering preterm.

Twenty mothers of preterm babies who had survived to 1 year old, were matched for age and parity of the mother and time of birth of the baby, with 20 mothers delivering fullterm. Bone mineral, body composition and anthropometric measurements were obtained for each mother and analysed using paired t-tests. The only significant difference (P < 0.01) between the groups was a lower fat-free mass in the preterm mothers calculated from skinfold thickness measurements.

Adipose Tissue↗
PubMed1993

Variation in lumbar spine and femoral neck bone mineral measured by dual energy X-ray absorption: a study of 329 normal women.

Reference ranges used in dual energy X-ray absorptiometry (DXA) have previously used piecewise linear fits to the whole data set for spine or femur bone mineral density (BMD) as a function of age. In a study of 329 Caucasian normal women we present a refinement to the normal range by fitting straight lines between quinquennial mean values of BMD for each site measured (lumbar spine, femoral neck and Ward's triangle). From the age of 40 years onwards the premenopausal women demonstrated minimal loss of BMD whereas postmenopausal women showed a rapid loss amounting to 27% in the lumbar spine, 27% in the femoral neck and 38% in the Ward's triangle region in the age range under examination. Comparison of quinquennial means for pre and postmenopausal women in age bands 45-49 years and 50-54 years shows that at these ages postmenopausal BMD is significantly lower than premenopausal BMD (P < 0.05). This finding suggests that separate normal ranges should be used for pre and postmenopausal women. As reduction in the production of oestrogen is a major factor in postmenopausal bone loss and oestrogen function is related to years since menopause (YSM), a more logical way of displaying postmenopausal normal BMD ranges would be in terms of YSM rather than chronological age. Such data are given in this paper.

Absorptiometry, Photon↗
PubMed1992

Bone ultrasonic attenuation in women: reproducibility, normal variation and comparison with photon absorptiometry.

The reproducibility of two methods of measuring broadband ultrasonic attenuation (BUA) in the calcaneus have been studied. An improvement in reproducibility in vivo from 9.6% to 2.8% between old and new techniques has been observed. Measurements of the calcaneus using BUA were correlated with measurements of bone mineral density measured by dual energy x-ray absorptiometry in the lumbar spine, femur and total body and bone mineral content in the distal and proximal forearm measured by single photon absorptiometry. For the older BUA technique the correlation coefficients ranged between r = 0.27 and r = 0.34. For the newer BUA technique the correlation coefficients ranged between r = 0.49 and r = 0.62 and were all significant (P less than 0.001).

Absorptiometry, Photon↗
PubMed1990

Spontaneous resolution of bone mineral depletion in preterm infants.

Fifteen preterm infants and 17 born at full term whose gestational ages ranged from 25 to 34 weeks and 38 to 42 weeks, respectively, were examined initially at postconceptional ages ranging from 38 to 44 weeks and subsequently at 46 to 71 weeks. Each examination included measurement of bone mineral content of the mid-forearm by single photon absorptiometry. For the preterm group, the mean (SD) value of bone mineral content at the first examination was 109.0 (27.6) mg/cm and was significantly lower than the corresponding value of 194.4 (19.6) mg/cm for the whole full term group. The mean subsequent rate of mineral accretion in the preterm group was 8.70 (4.60) mg/cm/week, the mean individual duration of observation being 9.7 weeks. Rate of mineral accretion for the full term group was independent of the duration of observation and averaged 1.60 (2.20) mg/cm/week. The difference between mean values of rate of mineral accretion in the preterm and full term groups was highly significant. Our results show that there is a phase of rapid mineral accretion starting at 40 weeks' postconception in preterm infants that substantially reduces the perinatal mineralisation deficit.

Absorptiometry, Photon↗
PubMed1989

Bone mineral content and body size 65 to 100 weeks' postconception in preterm and full term infants.

A total of 36 preterm and 22 full term infants were weighed and measured at 65 to 100 weeks' postconception. It was found that the preterm infants were on average significantly lighter by 1008 g and shorter by 3.8 cm than those born at full term. Despite the smaller size of preterm infants, mean values of bone mineral content in the mid-forearm were not significantly different between the two groups. In contrast, near 40 weeks' postconception the mean bone mineral content observed in 35 of the preterm infants was significantly smaller than that observed in eight of the full term infants. Our results suggest that there is a phase of rapid mineral accretion between 40 and 60 weeks' postconception. This 'catch up' in mineral accretion reduces the perinatal mineralisation deficit that might otherwise persist into childhood.

Body Height↗
PubMed1989

Osteopenia in extremely low birthweight infants.

Fifteen extremely low birthweight (ELBW) white infants (those weighing 1000 g or less) were observed at birth, within eight weeks of birth and near 40 weeks postconception. On the second and third occasions, weight, crown-heel length, and bone mineral content of their forearms were measured. Fifteen infants born at full term on whom similar measurements were made soon after birth acted as controls. Between 32 and 39 weeks the median weight of ELBW infants increased from 970 g to 1850 g and crown-heel length from 35.7 cm to 41.0 cm. There was no evidence, however, of bone mineral accretion in the measurement region; initial and final median measurements of bone mineral content were 76 mg/cm and 86 mg/cm, the median individual difference being only 4 mg/cm with an interquartile range of 25 mg/cm. Median weight, crown-heel length, and bone mineral content of the control group were 3270 g, 50.6 cm, and 196 mg/cm, respectively. Compared with the controls, ELBW infants at 39 weeks were a median (interquartile range) of 1420 (525) g lighter, 9.9 (3.9) cm shorter, and had a bone mineral content deficit of 108 (32) mg/cm. In terms of weight and crown-heel length ELBW infants at 39 weeks were comparable with infants born and observed at 32 weeks' gestation; compared with these infants the bone mineral content deficit in the ELBW group was about 33%.

Body Height↗
PubMed1989

Bone mineral accretion rate and calcium intake in preterm infants.

Thirty six preterm infants (20 boys) of 25 to 32 weeks' gestation were observed from birth to around 40 weeks' postconception. When oral feeding became possible, nine received mother's own breast milk (group B), 15 formula feed (group F), and 12 formula feed supplemented with calcium (5 ml 10% calcium gluconate/100 ml feed) and phosphorus (0.5 ml 17% potassium phosphate similarly) (group S). All received a daily supplement of 400 IU vitamin D. Intakes of calcium, phosphorus, vitamin D, energy, and fluid volume were recorded. When oral feeding started, and near 40 weeks' postconception, bone mineral content of the forearm was measured by photon absorptiometry; weight and crown-heel length were also measured. After logarithmic transformation of the measurements, there were no significant intergroup differences between the mean rate constants for weight or crown-heel length describing growth during the observation period. The mean rate constant for mineral accretion (M) was significantly higher in group S than in both the others. Pooling all data, M was significantly correlated with calcium intake but not with any other variable. Mineral supplementation of feed can reduce but not cure osteopenia of prematurity.

Bone Diseases, Metabolic↗