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Biomedical subjects

H Ringertz

Publications and source records attributed to H Ringertz.

At least 19 recordsLinked to original sources
PubMed2001

Pediatric PACS, Astrid Lindgren Children's Hospital at Karolinska Hospital, Stockholm, technical and practical aspects.

We present a filmless pediatric radiology department for the Stockholm area (1.8 million inhabitants) producing 50000 examinations per year. Seventy percent of the examinations are non scheduled, 50% are emergency cases out of office hours. The system is designed for high reliability operating with 99.7% uptime. A large number of daily conferences are held throughout the Children's Hospital at the various specialized departments, distributed through the intranet, with one pediatric radiologist attending. Instant reading is made in the majority of examinations and reports are available with images throughout the hospital including PC's at doctors rooms. The system uses conventional hardware and software with an open systems standard based approach. The system is highly appreciated by clinicians and has improved availability of radiology information.

Hospitals, Pediatric↗
PubMed2001

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). DESIGN: A 12-month, longitudinal, prospective study on a consecutively selected sample of healthy independent older people. SETTING: Men and women living in their own homes in the inner city of Stockholm (latitude 59.2 degrees N). PARTICIPANTS: Sixty-four healthy men (n = 13) and women (n = 51), age 79 to 96 (mean age 83.7) were requested to spend at least 3 hours per week outdoors during April through September. Fifteen of these, who failed to comply with the required time outdoors, constituted a separate group. Subjects with serious diseases and subjects with medication that could interfere with vitamin D metabolism or bone mineralization were excluded from the study. MEASUREMENTS: Daily dietary intakes of calcium and vitamin D were recorded on the basis of the subjects' recall. The participants kept a diary recording the time spent in sunlight and the area of skin exposed. Fasting blood samples were collected and analyzed on four occasions for 25OHD, intact PTH, and ionized calcium. BMD was determined at 6-month intervals in the femoral neck, using dual energy x-ray absorptiometry. RESULTS: At study start in the spring, 6% of the subjects had 25OHD levels below 10 ng/ml and 78% had levels below 31 ng/ml. Forty-seven percent had intact PTH levels above the upper limit of the reference range (8-51 ng/L). Seasonal variations in the serum levels of 25OHD (P <.001), intact PTH (P <.001) and ionized calcium (P <.001) were observed only in the group with > or =3 hours of weekly outdoor daylight exposure. The 25OHD levels in autumn were positively correlated with the number of hours spent outdoors during the preceding summer (r = 0.63, P <.001). In the whole group and in the group with weekly outdoor exposure of > or =3 hours, there were no significant changes detectable in mean values of femoral neck BMD during the study year. Femoral neck BMD, expressed as Z-score, was significantly and positively correlated with serum 25OHD (r = 0.38, P =.003 after summer; r = 0.37, P =.003 after winter). CONCLUSION: The seasonal changes in serum levels of 25OHD, PTH, and ionized calcium and the positive correlation between femoral neck BMD and 25OHD indicate that regular outdoor daylight exposure during the summer could enhance calcium homeostasis and possibly bone health, even among very old people living at northerly latitudes.

Aged↗
PubMed2000

[Technical improvements in bone densitometry].

The SBU-report no 127 "Mätning av bentäthet" [Measuring bone density] was published in 1995 and its conclusions are still valid. However, since then new treatment modalities have placed increasing demands on the diagnostic capability and performance of the apparatus used for bone densitometry. The most well-established and widely used technique for bone mineral determination is dual energy X-ray absorptiometry. Several international studies have shown that quantitative ultrasound should not be used for diagnosis or monitoring of osteoporosis. The reproducibility of one's method is important for monitoring, and the method's accuracy is important for diagnosis. Due to the limitations of the techniques and the slow turnover of the skeleton, repeated measurements are not meaningful until at least two years have passed. In order to maintain high quality in measurement results it is important to have trained personnel and to have a regular quality assurance program for the apparatus.

Absorptiometry, Photon↗
PubMed2000

Added value of CEA scintigraphy in the detection of recurrence of rectal carcinoma.

PURPOSE: To explore the diagnostic value of immunoscintigraphy compared to CT and/or MR imaging in the diagnosis of local recurrence (LR) of rectal cancer. MATERIAL AND METHODS: Forty-six patients suspected of having LR of rectal cancer were retrospectively studied. Carcinoembryonic antigen (CEA) scintigraphy findings were compared to CT and/or MR in all patients, and with data from surgery and morphology (31 patients), biopsy (7 cases) and follow-up (8 patients). RESULTS: CEA scintigraphy was not complementary to CT and/or MR in the detection of LR. Two false-positive and 14 false-negative diagnoses of LR occurred with CEA scintigraphy. Distant metastases including metastatic lymph nodes were found by this method in only 7 of 27 patients with proven metastases. CT/MR were able to demonstrate these metastases in 21 of 27 patients. CONCLUSION: Accuracy and sensitivity of CEA scintigraphy in the detection of LR and distant metastases is lower than that of CT and/or MR. However, CEA scintigraphy seems to have a high specificity and could therefore be used in patients with a strong clinical suspicion of LR but negative CT/MR investigations. Available diagnostic methods have limitations in differentiating between benign, post-treatment changes and LR of rectal cancer and in staging of malignant disease.

Adult↗
PubMed2000

Bone mass and body composition of adult women with congenital virilizing 21-hydroxylase deficiency after glucocorticoid treatment since infancy.

AIM: To study bone mass, body composition and androgenic/anabolic activity in adult women with virilizing congenital adrenal hyperplasia (CAH) treated with glucocorticoids since infancy and to relate this to the postmenarcheal glucocorticoid impact. PATIENTS AND METHODS: Thirteen adult women with virilizing CAH treated with gluco- and mineralocorticoids but otherwise medicine-free were investigated with respect to bone mineral content, body composition by dual energy X-ray absorptiometry and endocrine status. In addition an index of accumulated postmenarcheal exogenous glucocorticoid impact was calculated. Seven of the patients had regular menstrual periods, and six were oligomenorrheic but responded with withdrawal bleedings on cyclic progestagens. The data for the patients were compared with those of age-matched healthy reference subjects. RESULTS: In spite of their shorter stature, CAH patients were significantly heavier and had a significantly higher body mass index and fat/lean body mass ratio than the controls. Their bone mineral area density (BMD) was significantly lower than that of the controls. Serum concentrations of androgens were subnormal in all except two of the patients. Strong negative associations were found between BMD and the calculated index of accumulated postmenarcheal glucocorticoid dose but not between BMD and circulating androgen levels. CONCLUSION: The results indicate that glucocorticoids were administered in excess in most of the patients, resulting in subnormal levels of adrenocortical androgens, increased body fat and bone demineralization. Increased catabolic activity due to hypercortisolism rather than decreased androgenic/anabolic steroids is probably the major cause of the subnormal BMD in the treated CAH patients.

Absorptiometry, Photon↗
PubMed1999

The correlation between R2' and bone mineral measurements in human vertebrae: an in vitro study.

The aim of this study was to investigate whether MR imaging of trabecular bone structure using magnetic inhomogeneity measurements is related to the amount of bone mineral in human vertebrae. Weight, bone mineral content (BMCDXA), bone mineral per area (BMADXA) and bone mineral density (BMDCT) were determined in 12 defatted human lumbar vertebrae (L2-L4) by weighing, dual X-ray absorptiometry (DXA) and CT. Inhomogeneity caused by susceptibility differences between trabecular bone and surrounding water was studied with MR imaging at 1.5 T using the GESFIDE sequence. The pulse sequence determines the transverse relaxation rate R2(*) and its two components, the non-reversible transverse relaxation rate (R2) and the reversible transverse relaxation rate (R2'; i. e. relaxation rate due to magnetic susceptibility) in a single scan. Voxel size was 0.9 x 1.9 x 5.0 mm. Positive significant correlations between R2' and weight, BMCDXA, BMADXA and BMDCT were observed (r > 0.61 and p < 0.05 for all). Unexpectedly, R2 was also positively correlated with weight, BMCDXA and BMDCT (r > 0.66 and p < 0.05 for all), but not with BMADXA. Thus, R2' measurements are related to the amount of bone mineral, but they also provide information which is not obtainable from bone mineral measurements.

Absorptiometry, Photon↗
PubMed1999

Orientation of trabecular bone in human vertebrae assessed by MRI.

The aim of the study was to assess the relative number of bone trabeculae in different orientations by using magnetic inhomogeneity measurements by MR imaging. Twelve defatted human vertebrae (L2-L4) were studied by MR imaging and CT. In the MR measurements the reversible transaxial decay rate, R2', was determined using the GESFIDE sequence. The relative contribution to R2' of bone trabeculae oriented along the x (R2'x), y (R2'y) and z (R2'y) axes was assessed, by rotation of the specimen in the magnetic field. The results were validated by CT measurements of trabecular structure at a resolution of 0.2 x 0.2 x 1 mm. using custom-made software. R2' ranged from 4.9 to 32 s-1. After separation, theoretical R2'x ranged from 2.3 to 10.7 s-1, R2'y ranged from 2.6 to 14.0 s-1 and R2'z ranged from 4.7 to 17.9 s-1. The number of bone trabeculae per millimeter identified in axial CT images ranged from 0.15 to 0.38 and from 0.039 to 0.22 per millimeter in sagittal images. The difference between axial and sagittal CT images was statistically significant and due to anisotropic voxels. The correlation between R2' and the number of bone trabeculae per millimeter was statistically significant (r = 0.83, p < 0.001 for x orientation: r = 0.63 for y orientation, and r = 0.59 for z orientation, p < 0.05 for both). The relative amount of bone trabeculae in different orientations can be assessed in vitro using R2' measurements.

Aged↗
PubMed1999

Vitamin D status, parathyroid function and femoral bone density in an elderly Swedish population living at home.

The aim of this study was to determine vitamin D status and bone mineral density (BMD) in elderly, independent Scandinavians. A cross-sectional examination was conducted in a sample of 104 subjects (mean age 84.5 years), for possible correlations among anthropometric data, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, intact parathyroid hormone (PTH) and femoral neck BMD. Daily dietary calcium and vitamin D intakes were below the recommended levels. Five percent of the subjects were taking calcium, and 30% vitamin D supplements. Previous fragility fracture was reported in 30% of the men, and 55% of the women. Higher mean values of serum 25-hydroxyvitamin D (p = 0.03) and femoral neck BMD (p = 0.03) were recorded in subjects spending > or = 3 hours outdoors weekly. Independently of time spent outdoors, subjects taking daily supplements of vitamin D (on average 5 micrograms) had higher 25-hydroxyvitamin D (p < 0.001) levels, without significant changes in femoral neck BMD values. Serum levels of intact PTH (reference range 8-51 ng/L) were elevated in 41%, of which 5% had mild primary hyperparathyroidism. Serum levels of 25-hydroxyvitamin D (reference range 10-65 ng/mL) and 1,25-dihydroxyvitamin D (reference range 15-55 pg/mL) were below the reference ranges in 4% and 5% of the subjects, respectively. When serum levels of 25-hydroxyvitamin D were lower than approximately 30 ng/mL, the serum intact PTH values began to increase from a level of 43 pg/mL. This threshold most probably reflected a more relevant value of vitamin D insufficiency, indicating that 45% of our subjects rather than 4% actually had hypovitaminosis. Multiple regression analysis demonstrated femoral neck BMD to be significantly and positively associated with higher body mass index, male gender, no history of fragility fracture and 25-hydroxyvitamin D (R2 = 0.39). It is concluded that in this sample of healthy elderly people who regularly spend time outdoors, vitamin D levels leading to secondary hyperparathyroidism seem to be a major cause of osteoporosis. Correcting chronic dietary calcium deficiency is likely to eliminate another factor contributing to poor bone health.

Absorptiometry, Photon↗
PubMed1998

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.

Absorptiometry, Photon↗
PubMed1997

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.

Animals↗
PubMed1997

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.

Adipose Tissue↗
PubMed1995

Bone mineral content of young female former gymnasts.

Intense physical exercise and diet restriction could result in delayed puberty and have a negative influence on the acquisition of peak bone mass during puberty. Nineteen young women who had been in elite gymnastic training during their prepubertal and pubertal years were investigated with regard to their health, menstrual data and bone mineral areal mass (BMA). Twenty-one women of comparable age served as controls. The age of menarche of the "former" gymnasts and the controls was 14.8 +/- 1.8 and 12.1 +/- 1.4 years, respectively. Fourteen of the gymnasts had been or were using oral contraceptives (OCs) and most of the non-users now had regular menstrual periods. During the years preceding the study, physical activity among the "former" gymnasts had gradually declined. Although the gymnasts had had a delayed puberty, no difference was found in total body or spinal BMA compared to the healthy controls. Their normal BMA in early adulthood could reflect a catch-up due to a combination of decreasing athletic activity, normal menstrual cycles and intake of OCs.

Adolescent↗
PubMed1995

Bone mineral density in middle-aged women with Turner's syndrome.

Bone mineral density (BMD), bone mineral content and body composition were determined in 47 middle-aged (mean age 47.9 +/- 1.1 years) women with Turner's syndrome. Bone mineral density was measured in the forearm, femoral neck and total body. The women investigated had a BMD lower than the normal mean. When expressed as Z scores (individual values compared to normal reference data matched for age, weight and sex), the median Z score of the total body was -1.23. When comparing women with the karyotype 45,X and mosaic women, the latter showed a higher BMD in all sites of measurement. Duration of hormonal replacement therapy (HRT) differed significantly between the mosaic and the 45,X women, with a longer duration in the mosaic group (20.7 +/- 2 vs 12.1 +/- 2.6 years; p < 0.01). The duration of HRT was found to be the more important factor to maintain bone mass, not the karyotype. Bone mineral density increased with years of HRT but not until after > 20 years of HRT could a significant difference be shown between the women with HRT < or = 20 years and those with HRT > 20 years. No correlation was found between BMD and body weight, body fat or percentage body fat. Whether the osteopenia found in women with Turner's syndrome is similar to that found postmenopausally or is a specific form related to the chromosome aberration remains to be investigated further. The present data support a relation to estrogen deficiency.

Absorptiometry, Photon↗
PubMed1994

Role of MRI in the evaluation of ambiguous genitalia.

Diagnostic accuracy of magnetic resonance imaging (MRI) interpretation was assessed prospectively in patients with ambiguous genitalia or intersex problems. MRI depiction of the uterus was possible in 93%, the vagina in 95%, the penis in 100%, the testis in 88%, and the ovary in 74% of patients. The strength of MRI lies in the multiplanar capability and tissue characterization by means of T1- and T2-weighted sequences. MRI contributes to accurate morphologic evaluation of müllerian duct structures, the gonads, and the development of the phallus, all of which are essential for appropriate gender assignment and planning of surgical reconstruction.

Adolescent↗
PubMed1994

Bone mineral density during long-term prophylaxis with heparin in pregnancy.

OBJECTIVE: We studied the effect of long-term heparin treatment on bone mass during pregnancy. STUDY DESIGN: Thromboprophylaxis with heparin was given to 39 women during pregnancy for a mean of 28 weeks and for an average of 6 weeks post partum. Bone mineral density measured with single-photon absorptiometry of the distal and ultradistal parts of the forearm was determined at the time of the start of heparin treatment (mean, twelfth week of gestation), immediately post partum, and on average 7 weeks post partum. The mean dosage of heparin was 17,300 IU/day. A control group of 34 normal pregnant women was studied for comparison. RESULTS: In women treated with heparin, there was almost a 5% reduction in trabecular bone during pregnancy (p < 0.01) and an insignificant recovery post partum. There were no significant changes in bone mass during pregnancy or in the puerperium in the control group. CONCLUSION: Long-term treatment with heparin during pregnancy is associated with bone loss, but indications of reversible changes are observed.

Adult↗