Hans Ringertz

Seasonal Variations in Serum Levels of 25‐Hydroxyvitamin D and Parathyroid Hormone but no Detectable Change in Femoral Neck Bone Density in an Older Population with Regular Outdoor Exposure

OBJECTIVES: To investigate the influence of season and outdoor daylight exposure on serum levels of 25‐hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), ionized calcium, and femoral neck bone mineral density (BMD).

Nutritional status, as determined by the Mini-Nutritional Assessment, and osteoporosis: a cross-sectional study of an elderly female population

Objective:To investigate the relationship between osteoporosis and nutritional status as determined by the Mini-Nutritional Assessment (MNA).Design:A cross-sectional study.Setting:Stockholm, Sweden.Subjects:A total of 351 elderly free-living women (mean age 73±2.3 years).Methods:MNA (range 0–30 points; <17 indicates malnutrition, 17.5–23.5 risk of malnutrition and ⩾24 well nourished), measurements of bone mineral density of the left hip and lumbar spine using Hologic QDR 4500, and of the heel using Calscan DEXA-T.Results:The median MNA score was 27 (range 12.5–30). One woman was classified as malnourished and 7.4% were at risk of malnutrition. Osteoporosis of the femoral neck was observed in 22% and a fracture after the age of 50 was reported by 31% of the participants. The following items in the MNA questionnaire exhibited an increased risk of having osteoporosis in the femoral neck and/or total hip: an MNA score of <27 (odds ratio (OR)=2.09; CI=1.14–3.83); a mid-arm circumference of less than 28 cm (OR=2.97; CI=1.29–6.81); and regular use of more than 3 drugs each day (OR=2.12; CI=1.00–4.50). A body weight of more than 70 kg exhibited a decreased risk of having osteoporosis (OR=0.31; CI=0.14–0.70).Conclusions:In general, the nutritional status was good in this population of free-living elderly women. Nevertheless, half of the women who displayed an MNA score <27 points had a twofold increased risk of having osteoporosis.Sponsorship:Karolinska Institutet, Stockholm County Council.

Effect of Bone Density of the Head on Total Body Dexa Measurements in 100 Healthy Swedish Women

Purpose: The aims of this study were to examine the bone areal density of the head and how it varied in relation to the density of the rest of the skeleton, and with age, and body mass index (BMI). Our intention was to study the feasibility of excluding the head from the rest of the body, a method which might improve the fracture prediction power of bone mineral measurements. Material and Methods: Bone mineral per area (BMA) and bone mineral content (BMC) (g) were determined in 100 consecutive female volunteers, aged 17 to 78 years, with total and partial body measurements. Results: BMC of the head was found to be 20.2±2.2% of that for the total body. The BMA of the head was 2.38±0.21 times higher than that of the rest of the body. The correlation between the BMA of the head and the rest of the body was significant (r=0.73). The average change in z-score (referred to the same age group in our material) was 0.20 when the head was excluded from total body BMA. The BMA of a) total body, b) total body, head excluded, and c) head decreased with age. The BMA of the head was correlated to BMI in the older age groups (p<0.01). The relative statistical uncertainty for repeated measurement of head BMA was 1.8%. Conclusion: The change of the bone density of the head with age and BMI, in comparison to that of the rest of the skeleton, suggests that when the head is excluded from total body BMA better predictive value for fracture risk is obtained.

Quantitative density-time measurements in the lungs of children with suspected airway obstruction using ultrafast CT.

Fourteen children under 3 years of age with possible airway obstruction were evaluated with an ultrafast CT scanner, Imatron C-100. Serial 0.05-second multilevel scans were obtained through the chest at rates of 17 images per second. No patient sedation or contrast medium was used. Time-density curves generated over each lung and specific pulmonary zones were compared to characterize the normal variation of density during inspiration and expiration and to determine abnormal patterns associated with airway obstruction. There was a high, positive correlation value (r>0.79) between time/density curves over those pulmonary regions in which there was no focal bronchial obstruction and a low, negative correlation value (r=< −0.58) with bronchial obstruction. Three studies with reconstruction artifacts were excluded. Furthermore, the results indicate that young children generally have denser lungs, particularly in expiration, than older children or adults. This preliminary study suggests that ultrafast CT offers a promising, unique, rapid and noninvasive approach for diagnosing airway obstruction in childhood.

Total body bone mineral measurements in children with Prader-Willi syndrome: the influence of the skull's bone mineral content per area (BMA) and of height

Background. The aim of this study was to investigate the influence of body height and growth on total body measurements with dual energy X-ray absorptiometry (DEXA) in children. Material and methods. Seventeen children with Prader-Willi syndrome were studied as part of a clinical investigation of the effect of growth hormone (Genotropin) treatment. Bone mineral areal mass (BMA), in g/cm2, was studied with DEXA at 0, 12, 24 and 30 months after the start of the study. The effect of increased bone volume on BMA was studied by making a rough estimate of bone width, which was correlated with BMA. Results. There was a weak correlation between total body BMA and body height (r = 0.58), which increased after exclusion of the head (r = 0.84). The BMA of the head was more than twice as high as that of the rest of the body. In the shortest children more than 50 % of the total bone mineral was contained in the skull, which decreased with height to below 20 % in the tallest children. The correlation between the so-called bone width and BMA (total body, head excluded) was 0.97. Conclusion. The results indicate that (a) the bone mineral content (BMC) of the head and (b) the bone volume and body height have a major influence on BMA measurements with DEXA in children. A theoretical method for evaluating the relative bone density (g/cm3) has also been described.

Experimental correlation between T2* and ultimate compressive strength in lumbar porcine vertebrae

RATIONALE AND OBJECTIVES The authors used magnetic resonance (MR) imaging to investigate the correlation between T2* measurements of trabecular bone and the ultimate compressive strength of lumbar porcine vertebrae. METHODS Five pigs that weighted 25-32 kg were sacrificed and imaged with a 1.5-T MR system. T2* of the lumbar vertebrae was measured from gradient-echo images. The vertebrae were individually compressed at a fixed speed in the direction of the spine until crushed. The maximum load a vertebra could resist was recorded. RESULTS T2* ranged from 7.1 to 14.5 msec. T2* determined from 5-mm coronal sections differed from that determined from axial and sagittal sections (P < .05). Between 2.9 and 5.4 kN of force (296-550 kg) was needed to crush a vertebra. A linear correlation between the ultimate compressive strength and T2* of all vertebrae was observed for all imaging planes and section thicknesses (P < .001, except for 10-mm sagittal images, for which P < .002). The T2* determined for the axial plane showed the best correlation with the ultimate compressive strength (r = -0.83). CONCLUSION The correlation between T2* values and vertebral strength indicates that MR imaging may potentially be used to predict fracture risks in patients.

Effects of standing on bone density and hip dislocation in children with severe cerebral palsy

Abstract The aim of the study was to evaluate whether standing time associates with bone density and/or hip dislocation in children with severe cerebral palsy. The study design was cross-sectional and descriptive. Eleven boys and seven girls, median age 10.5 years, with severe cerebral palsy participated. Spasticity was measured with modified Ashworth scale. Seven children had scores of 0–1, and 11 had scores of 2–4. Eight of 18 had insulin-like growth factor-I levels lower than −2 standard deviations below the age-matched mean. Time spent in the Standing shell was recorded. Bone mineral density levels determined using dual energy X-ray absorptiometry and hip X-ray were evaluated. Time spent in the Standing shell was 40 min/day (range=4–164). The lumbar spine bone mineral density was 73% of that of age-matched able-bodied controls. Standing time was not associated with bone mineral density, but in 11 children with modified Ashworth scale scores of 2–4, standing time was significantly and negatively associated with hip dislocation. We conclude that time spent in the Standing shell in these 18 children did not affect whole body bone mineral density. In children with spasticity, the association to hip dislocation was significantly negative.

Gradient-echo magnetic resonance signal decay in a porcine vertebral body model: Influence of chemical shift

RATIONALE AND OBJECTIVES This study investigates how magnetic resonance (MR) signal and T2* of trabecular bone are affected by chemical shift. METHODS Five pigs were sacrificed, and 150 gradient-echo MR images with increasing echo times (TEs) were obtained of the lumbar spine. Two vertebrae were excised, defatted, and imaged. Commercial fat-protein emulsions with 40%, 27%, and 15% concentrations of fat were studied. Regions of interest in subcutaneous fat (n = 3), bladder (n = 4), vertebral body (n = 10), and defatted vertebral body (n = 10) were used to study decay of signal intensity. RESULTS MR signal intensity of the vertebrae decreased with a superimposed modulation. The periodicity was 4.65 msec (range, 4.60-4.68 msec). At a TE of 0 msec, a phase shift of 24 degrees (range, 14 degrees-37 degrees), which corresponds to a shift in TE of 0.31 msec at 1.5 T, was present. In the fat-protein emulsions, the amplitude of the modulation increased with the amount of fat. CONCLUSION Chemical shift and the amount of fat affects T2* measurements.

Magnetic resonance imaging in pediatric hematology/oncology. Part 1. Basic technology

Magnetic resonance imaging (MRI) is a promising new diagnostic modality that is well suited for the evaluation of children with hematological or oncological diagnosis. The side effects of ionizing radiation are avoided, the tomographic pathological anatomy in three orthogonal planes can be obtained, and differences between normal and abnormal tissues are often present. In order to present our preliminary clinical experience with MRI in pediatric hematology and oncology, the historical background of MRI, the technique, and possibilities for tissue characterization are reviewed.

Magnetic resonance imaging in pediatric hematology/oncology. Part II. Illustrative cases and assessment of technique.

Preliminary clinical experience with magnetic resonance imaging (MRI) in 28 pediatric patients with 20 different hematological diseases, benign tumors, or malignant neoplasms is presented. The clinical results are presented in the form of case presentations that are discussed in the context of alternative diagnostic imaging modalities. Also discussed are the known biological effects, or lack thereof, the need for sedation, the effect of motion, the effect of MRI on foreign metallic objects, the financial considerations, and the trends for the future of MRI. This imaging modality has many unique merits. Present difficulties should be overcome by future innovations, making MRI even more efficacious for the diagnosis of blood diseases and cancer in children.