Magnetic resonance imaging changes in uterine zonal anatomy during a conception cycle.
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Adult↗
Biomedical subjects
A Horsman
Publications and source records attributed to A Horsman.
Quantitative analysis of multi-slice Gd-DTPA enhanced dynamic MR images using an automated simplex minimization procedure.
Quantitative analysis of Gd-DTPA enhanced dynamic MR images has potential for discriminating lesions, especially because the introduction of clinical fast imaging techniques has enabled good sampling of the relatively rapid Gd-DTPA wash-in curves. Analysis of such data requires curve fitting to a nonlinear model, which to date has been performed using a nonlinear least squares (NLLS) fitting procedure. However, this method often fails to converge to the appropriate minima without good initial parameter estimates when multi-exponential models are involved, making automated analysis of complete multislice or volume data sets problematic. In this report we demonstrate the robust performance of a simplex minimization procedure compared with NLLS, by the method of Marquardt, using a Monte Carlo simulation. Further, we illustrate the applicability of such a technique to the analysis of dynamic contrast enhanced images on a pixel-by-pixel basis. As a preliminary example, the technique is applied to a breast lesion but is expected to be suitable for examination of many lesion types.
Algorithms↗
Magnetic resonance imaging and transvaginal ultrasound of the uterus prior to embryo transfer.
This study was designed to investigate the role of magnetic resonance (MR) imaging in predicting the outcome of in-vitro fertilization (IVF)/embryo transfer treatment by seeking differences in receptive compared to unreceptive endometria. Women about to undergo embryo transfer were submitted to both vaginal ultrasound and MR imaging. Measurements were obtained of the thickness, cross-sectional area and volume of uterine layers and of the MR signal intensity ratios between layers. Measurements were compared with the occurrence of subsequent successful implantation. Although there was no association with either the quantity or the relative signal intensity of the endometrium, an interdependence was demonstrated between both the endometrium/myometrium and myometrium/junctional zone signal intensity ratios and subsequent successful implantation (P < 0.037 and < 0.004 respectively). It is concluded that MR imaging may provide unique information which may help in predicting the outcome of IVF/embryo transfer treatment and in understanding implantation. Significant differences were seen in the relative MR signal intensities of the myometrium.
Adult↗
Fingers: three-dimensional MR imaging and angiography with a local gradient coil.
The authors interfaced a 12-cm-diameter local gradient coil with a solenoid radio-frequency coil (2.2-cm internal diameter, 1.4-cm long) to a recalibrated clinical magnetic resonance imaging system. Three-dimensional gradient-echo imaging and phase-contrast angiography were performed on the fingers of five healthy volunteers (four men and one woman, aged 23-33 years). Data sets (256 x 256 x 28) were acquired with spatial resolution of 100 x 100 x 500 microns in 6 minutes 51 seconds. The angiograms clearly delineated blood vessels that were less than 1 mm in diameter.
Adult↗
Dynamic contrast-enhanced and fat suppressed magnetic resonance imaging in suspected recurrent carcinoma of the breast: preliminary experience.
20 women with suspected recurrent breast cancer who had undergone previous breast-conserving operations were investigated using dynamic contrast-enhanced gradient echo (GRE) and fat suppressed spin echo (SE) magnetic resonance (MR) imaging. Histologically confirmed recurrent tumour was readily recognized on dynamic GRE scans by virtue of rapid, early and avid enhancement. Benign scars enhanced more slowly and reached lower magnitudes of enhancement. Fat suppressed SE images, which were typically acquired 10 min after contrast administration, were sensitive for the detection of tumour recurrence but lacked specificity. Early scanning after contrast administration offers the best prospects for distinguishing tumour recurrence from benign scarring. The criteria used to distinguish these two entities are highly dependent on the scan technique and the time at which images are obtained post-contrast.
Aged↗
Estimation of body composition from bioelectrical impedance of body segments: comparison with dual-energy X-ray absorptiometry.
In twenty-eight healthy subjects, ten men and eighteen women, with a range in body mass index (BMI) of 17.9-31.6 kg/m2 and an age range 20-60 years, body composition was estimated by dual-energy X-ray absorptiometry (DEXA), skinfold anthropometry (SFA) and bioelectrical impedance analysis (BIA) of the 'whole body' and body segments. In thirteen subjects muscle mass was also estimated by 24 h urinary creatinine excretion. The relationship between fat-free mass (FFM) determined by DEXA and the impedance index of each body segment (calculated as length2/impedance (Z)) was analysed. The strongest correlation was between FFM (DEXA) and height2/'whole-body' Z (ZW) (r 0.97 for the combined sexes, standard error of estimate (SEE) 2.72 kg). Separate prediction equations were found to be necessary for males and females when estimating FFM from BIA measurement of the arm (for men, r 0.93, SEE 1.98 kg; for women, r 0.75, SEE 2.87 kg). Muscle mass derived from 24 h creatinine excretion showed weak correlation with FFM (DEXA) (r 0.57, P = 0.03) and no correlation with FFM (SFA). FFM (SFA) correlated well with both FFM (DEXA) (r 0.96, SEE = 3.12 kg) and with height2/ZW (r 0.92, SEE 4.52 kg). Measurement of the impedance of the arm offers a simple method of assessing the composition of the whole body in normal individuals, and it appears comparable with other methods of assessment.
Absorptiometry, Photon↗
Primary generalized osteoarthritis and bone mass.
The association of OA with increased bone mass is controversial. This study measured BMD at the hip and spine and total body bone mineral (TBBM) by dual energy X-ray absorptiometry, and BMD at the distal forearm by single photon absorptiometry in 20 post-menopausal women with primary generalized OA. The data were compared with those from 89 normal controls. Osteoarthritic women had significantly increased BMD at the spine (P < 0.001), distal forearm (P < 0.05) and increased TBBM (P < 0.01), but no difference was seen at the femoral neck. These differences were not explained by obesity. The influence of mobility is discussed.
Aged↗
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↗
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↗
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↗
Intertrochanteric femoral fractures. Mechanical failure after internal fixation.
In a prospective study we assessed the causes of mechanical failure in a series of 230 intertrochanteric femoral fractures which had been internally fixed with either a sliding hip screw or a Küntscher Y-nail. The overall rate of mechanical failure was 16.5%; cutting-out of the implant from the femoral head was the cause in three-quarters of the instances. Implants placed posteriorly in the femoral head cut out more often (27%) than those placed centrally (7%). The cut-out rate was also determined by the quality of the fracture reduction, but age, walking ability and bone density (assessed by the Singh grade and metacarpal indices) had no significant influence. We conclude that these fractures should be reduced as accurately as possible and it is imperative that the implant is placed centrally within the femoral head.
Aged↗
Spinal osteoporosis in men.
In 94 men with crush fracture, 40 were found to have primary osteoporosis. Cross-sectional measurements of a number of variables related to bone in these 40 patients were compared to the values in various groups of healthy men aged 20-96. In healthy men, metacarpal and femoral cortical area/total area, bone volume, osteoid surfaces, seam and trabecular width, plasma dihydroepiandrosterone and estrone, and radiocalcium absorption fell with age, whereas eroded surfaces, trabecular number, urine hydroxyproline and calcium/creatinine ratios, plasma alkaline phosphatase, estradiol, androstenedione, cortisol and testosterone remained constant with age. As compared with healthy men, men with primary osteoporosis had reduced femoral cortical area/total area (P less than 0.05), and Singh grade (P less than 0.001) and in seven there was a history of forearm or femoral fracture. On iliac crest biopsy, bone volume (P less than 0.001) and trabecular number (P less than 0.01) were decreased. Plasma alkaline phosphatase (P less than 0.02) was increased but urine hydroxyproline and calcium excretion were not significantly raised. Calcium balance was negative due to failure of absorption to match urinary calcium loss and radiocalcium absorption (P less than 0.01) and plasma 1,25-dihydroxyvitamin D (P less than 0.05) were reduced.
Adult↗
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↗
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↗
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↗
Mineral accretion in the human fetus.
Bone mineral content of the mid forearm was measured by photon absorptiometry in 73 white singletons (36 boys, 37 girls) born between 18 and 43 weeks' gestation. Results obtained within two weeks of birth for liveborn infants were used to establish bone mineral deposition curves approximating normal in utero development. Results for stillborn infants indicated a retardation of bone mineralisation relative to liveborn infants. This has important implications concerning previous estimates of daily calcium needs for preterm infants. Eleven liveborn Asian singletons and nine pairs of white twins were examined similarly. With respect to bone mineral content, weight, and crown-heel length, Asians with gestational ages over 35 weeks and twins were closely comparable with their white singleton peers. Asians under 35 weeks tended to be smaller than white singletons of comparable age.
Asia↗
Mineral content of rib bone in infant deaths.
The mineral content of rib bone in infants who died unexpectedly was similar to that among those who died after acute illnesses, and it was significantly associated with both crown to heel length and age. In those dying from chronic illnesses it was lower than in the other two groups.
Acute Disease↗
The selection of films and intensifying screens for use as a two-dimensional detector in a computed tomography system.
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Aluminum↗