Accuracy of lumbar spine bone mineral content by dual photon absorptiometry

The accuracy of measurement of the bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2) of the lumbar spine by dual photon absorptiometry (DPA) was estimated by means of two different spine scanners (a Nuclear Data 2100 and a Lunar Radiation DP3). The lumbar spines of 13 cadavers were used. BMC and BMD were measured in situ and on the excised vertebrae in a solution of water/ethanol; and covered with ox muscle/porcine muscle/lard. The actual mineral weight and areal density were determined after chemical maceration, fat extraction, drying to a constant weight, ashing for 24 hr at 600 degrees C, and correction for the transverse processes. The true are was measured by parallax free X rays and planimetry. All measurements of BMC or BMD were highly interrelated (r = 0.94-0.99). The standard error of estimate (s.e.e.) of BMC in situ versus BMC in water/ethanol was 5.2%. The agreement between the BMD values of the two scanners was very good (s.e.e. = 2.9%). BMC in situ predicted the actual vertebral mineral mass with an s.e.e. of 8.1%. BMD in situ and BMD in water/ethanol predicted the actual area density with s.e.e.s of 10.3% and 5.0%, respectively. This study discloses the correlation and accuracy error of spinal DPA measurements in situ in whole cadavers versus the actual BMC and BMD. The error, which is underestimated in in vitro studies, amounts to 10%.     

Normative data for lumbar spine bone mineral content in children: influence of age, height, weight, and pubertal stage

In 136 normal growing children between the ages of 1 and 18 yr, bone mineral content (BMC) at the level of the lumbar spine (L2-L4) was determined with a commercial dual-photon absorptiometer. BMC was calculated as BML (BMC per unit length) and BMD (BMC per unit surface). The mean lumbar spine BML of the studied children (2.53 +/- 0.86 gHA/cm) was significantly lower than the spinal mineral content of adults (4.26 +/- 0.57 gHA/cm). No sex difference existed in lumbar spine BMC. BML as well as BMD were highly dependent on age, body height, and body weight. During the prepubertal years, BML and BMD increased in a fairly rectilinear pattern. During puberty, BMC increased more rapidly: 40% for BMD and 77% for BML. For the entire group, the increase in BMC with age, height, and weight was best predicted by an exponential regression line analysis.     

Vertebral bone mineral measurement using dual photon absorptiometry and computed tomography

The lumbar spine of 14 cadavers was studied both by 153Gd dual photon absorptiometry (DPA) and quantitative computed tomography (QCT) at 96 and 125 kVp. The intact spine and the individual vertebrae were analyzed. After these measurements the ash content of the vertebral body, the posterior elements, and the transverse processes was determined. The fat content of the vertebral body as well as its volume was also measured. With DPA, the bone mineral content (BMC) determined in situ as well as on excised spine specimens correlated highly with the amount of total vertebral ash (r greater than 0.92, SEE less than 3.2 g). The bone mineral density (BMD, area density) of 3 lumbar vertebrae correlated accurately with the mean ash density of the vertebral body (r greater than 0.81, SEE less than 0.015 g/cm3). The so-called corpus density and central density determinations were less accurate. No difference in accuracy was found between measurements when using 3 mm and 4.5 mm step intervals. Variations in the distribution of mineral between the vertebral body and the posterior elements contribute to the error in predicting vertebral body mineral with DPA. QCT gave a smaller error when a cylindric portion of the vertebral body with a 20 mm diameter was measured compared with one with a 9 mm diameter, when the dual energy technique was used (p less than 0.01). With dual energy QCT a correlation was found between a center segment of 3 vertebrae in the lumbar spine and the mean ash density of the vertebral body of r = 0.92 (SEE = 0.010 g/cm3).(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise, bone mass and bone size in prepubertal boys: one-year data from the pediatric osteoporosis prevention study

This non-randomized prospective controlled study evaluates a daily school-based exercise intervention program of 40 min/school day for 1 year in a population-based cohort of 81 boys aged 7-9 years. Controls were 57 age-matched boys assigned to the general school curriculum of 60 min/week. Bone mineral content (BMC; g) and areal bone mineral density (aBMD; g/cm(2)) were measured with dual X-ray absorptiometry (DXA) of the total body, the third lumbar vertebra (L3) and the femoral neck (FN). Bone width for L3 and FN was calculated from the lumbar spine and hip scan. No differences between the groups were found at baseline in age, anthropometrics or bone parameters. The mean annual gain in L3 BMC was 5.9 percentage points higher (P<0.001), L3 aBMD a mean 2.1 percentage points higher (P=0.01) and L3 width a mean 2.3 percentage points higher (P=0.001) in the cases than in the controls. When all individuals were included in one cohort, the total duration of exercise including both school-based and spare-time training correlated with L3 BMC (r=0.26, P=0.003), L3 aBMD (r=0.18, P=0.04) and L3 width (r=0.24, P=0.006). The study suggests that exercise in pre-pubertal boys influences the accrual of bone mineral and bone width and that a 1-year school-based exercise program confers skeletal benefits, at least in the lumbar spine.     

Screening for abdominal aortic aneurysms during routine lumbar CT scan: modification of the standard technique

INTRODUCTION: Abdominal aortic aneurysms (AAAs) are often incidental findings in patients undergoing US, CT or MRI studies. The recommended field of view (FOV) for standard CT examinations of the spine is 14 cm. This FOV does not allow full visualization of the abdominal aorta. PURPOSE: To justify a larger FOV for male smokers older than 55 years and women older than 65 years, with a higher incidence of AAA. MATERIALS AND METHODS: The lumbar CT examinations of 100 consecutive patients (age: mean 68 years, range 55-85 years) presented with low-back pain were retrospectively reviewed. Measurements of the abdominal aorta and lumbar abnormalities were analysed. A control study in 850 patients who underwent abdominal CT scans for other causes was available for comparison. RESULTS: There were three men with AAAs measuring 4.5, 5.5 and 5.6 cm (mean 5.2 cm). Findings related to the clinical problem were disk prolapse or herniation, spondylosis, spinal stenosis and grade I spondylolesthesis. In the control group, 17 patients were found with AAAs with diameter greater than 4 cm (2%). CONCLUSIONS: Patients with low-back pain, older than 55 years of age, examined with lumbar spine CT, should also be screened for aortic disease, since the prevalence of AAA is similar with that of an age-matched control group. Appropriate modification in the applied FOV is recommended.     

Lumbar Spine MRI: Missed Opportunities for Abdominal Aortic Aneurysm Detection

PurposeThe US Preventive Services Task Force (USPSTF) recommends 1-time sonographic screening for abdominal aortic aneurysms (AAAs) in male smokers ages 65-75 and other selected individuals in this age group based on risk factors. Patients in this age range are frequent utilizers of lumbar spine MRI, in which the abdominal aorta is typically fully imaged. The purpose of this study was to assess the potential detection rate of AAAs on lumbar spine MRI performed in the USPSTF screening age range with systematic aortic measurement and the frequency with which AAAs are currently reported in practice.Materials and MethodsAll consecutive lumbar spine MRI exams performed without contrast at a single academic tertiary care center over a 1-year period (4/1/2016-3/31/2017) in patients ages 65-75 were retrospectively reviewed. Maximal anteroposterior, and transverse dimensions of the abdominal aorta were measured using axial T2-weighted images, supplemented with sagittal T2-weighted images if assessment was limited by field-of-view or artifact. The detection rate of AAA, defined as dilation of the aorta to a diameter of ≥3 cm, size of AAAs detected, and frequency with which AAAs were reported, were assessed. Differences in aortic diameters and aneurysm detection rates between genders were compared with the unpaired 2-sample t test.ResultsThree hundred and ninety-five lumbar spine MRIs were reviewed, 240 (60.8%) in women and 155 (39.2%) in men, with mean ± standard deviation (SD) age of 70.2 ± 3.2 years. AAAs were detected in 38/395 (9.6%) cases, most (33/38, 86.8%) of which were <4 cm. Of these, only 4 (10.5%) were reported by the interpreting radiologist; 3/4 (75%) corresponded to aneurysms ≥4 cm.ConclusionLumbar spine MRI performed in the USPSTF AAA screening age range, especially in men, facilitates frequent detection of AAA when the aorta is systematically measured. However, in typical lumbar spine assessment, AAAs are often underreported, particularly for smaller aneurysms.     

High femoral bone mineral content and density in male football (soccer) players

PURPOSE: This investigation examined the effect that long-term football (soccer) participation may have on areal bone mineral density (BMD) and bone mineral content (BMC) in male football players. METHODS: Dual energy x-ray absorptiometry (DXA) scans were obtained in 33 recreational male football players active in football for the last 12 yr and 19 nonactive subjects from the same population. Both groups had comparable age (23 +/- 4 yr vs 24 +/- 3 yr), body mass (73 +/- 7 kg vs 72 +/- 11 kg), height (176 +/- 5 cm vs 176 +/- 8 cm), and calcium intake (23 +/- 10 mg.kg(-1).d(-1) vs 20 +/- 11 mg.kg(-1).d(-1) (mean +/- SD). RESULTS: The football players showed 8% greater total lean mass (P < 0.001), 13% greater whole-body BMC (P < 0.001), and 5 units lower percentage body fat (P < 0.001) than control subjects. Lumbar spine (L2-L4) BMC and BMD were 13% and 10% higher, respectively, in the football players than in the control subjects (P < 0.05). Furthermore, football players displayed higher femoral neck BMC (24%, 18%, 23%, and 24% for the femoral neck, intertrochanteric, greater trochanter, and Ward's triangle subregions, respectively, P < 0.05) and BMD (21%, 19%, 21%, and 27%, respectively, P < 0.05) than controls. BMC in the whole leg was 16-17% greater in the football players, mainly because of enhanced BMD (9-10%) but also because of bone hypertrophy, since the area occupied by the osseous pixels was 7% higher (867 +/- 63 cm2 vs 814 +/- 26 cm2, P < 0.05). Leg muscle mass was 11% higher in the football players than in the control subjects (20,635 +/- 2,073 g vs 18,331 +/- 2,301 g, P < 0.001). No differences were found between the legs in either groups for BMC, BMD, and muscle mass. Left leg muscle mass was correlated with femoral neck BMC and BMD (P < 0.001), as well as with lumbar spine (L2-L4) BMC and BMD (P < 0.001). CONCLUSION: Long-term football participation, starting at prepubertal age, is associated with markedly increased BMC and BMD at the femoral neck and lumbar spine regions.     

Limited precision of lumbar spine dual-photon absorptiometry by variations in the soft-tissue background

The estimation error due to variations in soft-tissue baseline in lumbar bone mineral content (BMC) measured by dual-photon absorptiometry (DPA) was calculated with a new method of automatic baseline subtraction. In water phantom measurements, the s.d. of the soft-tissue (ST) baseline matched closely (r = 0.98) to the random error, calculated using 44 keV and 100 keV count rates and the directly determined baseline variations. In 21 volunteers and in 70 patients with osteoporosis, the ST variations were larger than the expected random error, revealing a source of error related to the inhomogeneity of soft tissue. The estimation error in BMC caused by ST variations was 0.7% in healthy subjects (mean BMC 40.5 gHA) and 1.5% in patients (mean BMC = 26.4 gHA). These results indicate that ST-related errors are an important limit to the precision of lumbar DPA measurements.     

Axial bone density in rheumatoid arthritis: comparison of dual-energy projection radiography and dual-photon absorptiometry

The usefulness of dual-energy projection radiography (DEPR) in the evaluation of rheumatoid arthritis was compared with that of dual-photon absorptiometry (DPA). Bone density measurements of the lumbar spine and the proximal femur were obtained with DPA in 75 patients (45 women and 30 men). For comparison, the bone density of the lumbar spine was measured with DEPR in a subset of 52 patients (33 women and 19 men). High correlation was documented between DEPR and DPA measurements of the lumbar spine. No significant relationship between bone density and age was observed, in contrast to the known relationship in healthy subjects regardless of sex, site of measurement, or measurement technique. Bone density values in the spine and the proximal femur were significantly reduced for both sexes as compared with matched normative data. Interlevel variation in lumbar vertebral density as measured with DEPR was not significantly different in patients with rheumatoid arthritis as compared with control subjects. Significant correlation between bone density determination and body weight, as well as duration of menopause, was noted, whereas duration of disease, functional status, and cumulative corticosteroid dose were not predictive. Rheumatoid arthritis did not appear to influence the relationship between DEPR and DPA measurements of the spine, and neither method nor site of measurement exhibited a consistent advantage in discriminating patients with rheumatoid arthritis from healthy control subjects.     

A comparison of single and multi-site BMC measurements for assessment of spine fracture probability

In a prospective study of 699 women, 39 new spine fracture cases were observed during a mean follow-up of 3.6 yr. Spine fracture incidence was compared to initial bone mineral content (BMC) of the calcaneus, distal radius, proximal radius, and the lumbar spine. BMC at all four sites was significantly related to spine fracture incidence. Women at -1 s.d. for calcaneal BMC had a sevenfold greater probability of spine fracture than women at +1 s.d.; women at -2 s.d. had a 50-fold greater probability than women at +2 s.d., even after adjustment for the effects of age. Combinations of BMC at two sites further strengthened the relationship to spine fracture; the best two-site combination is calcaneus and distal radius BMC. Thus women can be categorized and stratified according to future fracture risk, and the selection of postmenopausal women for preventive treatments can be guided by measurements of BMC.     

Effects of projective bone area size of the spine on bone density and the diagnosis of osteoporosis in healthy pre-menopausal women in China

The aim of this study was to understand the effects of projective bone area (BA) size of the spine on bone density and the diagnosis of osteoporosis. Measurements of BA, bone mineral content (BMC), areal bone density (aBMD) and volumetric bone density (vBMD) at the posteroanterior (PA) lumbar spine (vertebrae L2-L4) followed by a paired PA/lateral spine (L2-L4) were made using a dual-energy X-ray absorptiometry (DXA) fan-beam bone densitometer (Hologic QDR 4500A) in 1436 healthy pre-menopausal women aged from 20 to 56-years-old. At the PA and lateral lumbar spine, there was a significant positive correlation between BA and BMC (r=0.762 and 0.762, p=0.000) and aBMD (r=0.370 and 0.352, p=0.000), but not vBMD (r=0.000 and 0.102, p=0.813 and 0.063). When BA at the PA spine changed by one standard deviation (SD), BMC and aBMD correspondingly changed by 12.6% and 4.3% on the basis of their respective means while vBMD indicated no change. When a variation of 1 SD was observed in BA at the lateral spine, BMC, aBMD and vBMD correspondingly changed by 13.8%, 4.4% and 1.73% on the basis of their respective means. Through an intercomparison among large, intermediate and small BA groups, significant differences were found in the means of subject's height, weight, BMC and aBMD at the PA and lateral spine as well as the detection rate of osteoporosis by aBMD (p=0.000). Detection rates of osteoporosis by aBMD at the PA, lateral spine and vBMD in healthy pre-menopausal women aged from 40 years to 56 years were 4.5%, 16.4% and 9.7%, respectively, in the small BA group; 1.3%, 6.4% and 7.3%, respectively, in the intermediate BA group; and 0, 0 and 5.5%, respectively, in the large BA group. No significant differences were found in the detection rates of osteoporosis by vBMD among the groups. The results of multiple linear regression revealed that the major factors influencing BA of the lumbar spine was height. In healthy pre-menopausal women of the same race and age, the BA size of the lumbar spine would have significant influence upon aBMD and the diagnosis of osteoporosis, i.e. the larger the BA, the greater the aBMD and the lower the osteoporosis detection rate while conversely, the smaller the BA, the smaller the aBMD and the higher the osteoporosis detection rate. Though vBMD does not change with BA sizes of the lumbar spine, it is a sensitive marker for diagnosing osteoporosis.     

Comparative study of the performances of X-ray and gadolinium 153 bone densitometers at the level of the spine,femoral neck and femoral shaft

We investigated the precision of gadolinium 153 dual photon absorptiometry (DPA) and quantitative digital radiography (QDR) bone densitometers by determining in vitro and in vivo coefficients of variation (CV) of bone mineral density (BMD). In vitro, the long-term CV of spine phantom BMD measured weekly for 40 weeks was 1.2% and 0.7% for DPA and QDR, respectively. Simulating soft-tissue thickness with water, the CV of 6 repeat measurements of spine phantom at depths from 0 to 27 cm in 1 cm steps (a total of 168 measurements) increased from 0.1 % at 0 cm of water to 2.5% at 27 cm for DPA, and from 0.2% at 0 cm to 1.4% at 27 cm for QDR; mean CV of the 28 series (0–27 cm) was higher for DPA (1.2%±0.8%, mean±SD) than for QDR (0.7%±0.6%;P<0.001). With the hip phantom, femoral neck BMD was determined, and the CV was also dependent on water thickness; mean CV of the 20 series (0–10 cm) was 2.1%±1.2% for DPA and 1.3%±0.9% for QDR (not significant). In vivo, at the spine level, with DPA, mean CV of BMD measured 6 times after repositioning in 6 healthy volunteers was 3.8%±1.9% and 2.1%±0.7% with¹⁵³Gd activity of 0.46Ci and 1 Ci, respectively (BMD range: 0.796 1.247 g/cm², no significant difference between the two groups). Both values were significantly higher (P < 0.05) than mean CV with QDR: 1.0%±0.5% (12 subjects, same conditions; BMD range: 0.811–1.124 g/cm², no significant difference with the two previous groups). At the femoral neck and shaft levels, the mean CV observed with QDR tended to be lower as compared with DPA (not significant). At the three sites, BMD values obtained with DPA and QDR in 62 patients were highly correlated. In conclusion, our results indicate that the higher precision obtained with QDR is particularly significant at the lumbar spine level, but large biological variations in soft tissue thickness can still influence the degree of precision of BMD measurement.     

Assessment of vertebral mineral content by means of a single-crystal scintillation camera

Increasing interest in bone mass has led to dedicated commercial dual photon absorptiometry (DPA) instruments. We describe a method for the measurement of the mineral content of the lumbar spine using a scintillation camera. The most appropriate source(s) and collimator were investigated. An especially constructed arm placed the sources in the focal point of a converging collimator. Two single-peak sources, 99Tcm and 241Am, were used instead of dual-peak 153Gd source. Phantom studies showed no degradation of the results in water depths of up to 26 cm. Acquiring 10 Mcounts per image over a 300 cm2 field, a coefficient of variation (c.v.) of 1.7% was obtained. Reducing the total counts per image to 1 Mcount gave rise to a c.v. of 6.2%. Long-term measurements showed a c.v. of 1.1% for density, with a mean value of 0.98 gHa cm-2 compared to 0.90 for a commercial DPA instrument. Repeated measurements of the lumbar spine on 10 patients with a 2 week interval showed a c.v. of 5%. Comparative measurements were made between the scintillation camera and a commercial DPA instrument on six volunteers. Systematic higher results, similar to those observed with the phantom, were obtained with the scintillation camera. The reproducibility on a phantom and in patients is in the same range as commercial DPA instruments. The low cost related to the use of standard nuclear medicine equipment and to inexpensive radioactive sources represent definite advantages.     

Comparison of ultrasound transmission velocity with computed metacarpal radiogrammetry and dual-photon absorptiometry

The aim of our study was to evaluate the validity of a quantitative US technique for measuring the bone density of the proximal phalanges of the nondominant hand compared with computed metacarpal radiogrammetry and dual-photon absorptiometry (DPA) of the lumbar spine. Mean US bone velocity (UBV) correlated with mean metacarpal cortical index (MCI), with mean metacarpal bone density (MBD) and with bone mineral density (BMD) of the lumbar spine, whereas it was correlated negatively with age and menopause duration. The average UBV was significantly higher in premenopausal women than in postmenopausal women, and higher in normal lumbar DPA patients than in reduced lumbar DPA patients. We conclude that the US evaluation of the nondominant hand proximal phalanges may be a new alternative way for measuring bone mass in screening of osteoporosis. Correspondence to: A. Sili Scavalli     

Effect of a full and empty bladder on radiation dose to the uterus, ovaries and bladder from lumbar spine CT and X-ray examinations

This is a quantitative study of the effect of a full and empty bladder on the position of the uterus, ovaries and bladder relative to the lumbar spine. Data are used to estimate the difference in radiation dose to these organs from performing a lumbar spine CT investigation or a lateral lumbar spine radiograph with a full bladder compared with an empty bladder. 12 women of child-bearing age underwent pelvic magnetic resonance scans with full and empty bladders. The positions of the uterus, ovaries and bladder were matched with the radiation dose distribution that would have occurred either side of the inferior boundary of the CT scan volume and the lateral lumbar spine radiograph. These radiation dose profiles were measured on phantoms using a combination of ionization chambers and thermoluminescent dosemeters. When the bladder was emptied, the mean position of the endometrial cavity fundal tip moved from 4.1 cm to 6.1 cm inferior to the centre of the L5/S1 disc space, and from 0.87 cm to 1.12 cm anterior to the centre of the L5/S1 disc space. This movement on micturation would have reduced the mean dose to the uterine internal fundal tip during a pelvic CT scan from 6.8 mGy to 3.9 mGy, which represents a mean reduction of 43% (range 12-67%). The mean dose from a lateral lumbar spine examination would have been reduced from 197 microGy to 126 microGy. The change in ovary position results in the mean ovary dose being reduced by 48% for the lumbar spine CT scan and by 43%) for a lateral lumbar spine radiograph. When the bladder was emptied, the average position of the bladder wall moved from 7.2 cm to 10.3 cm inferior to the L5/S1 disc space. This change in bladder position reduces the mean dose to the wall of a full bladder from 5.7 mGy for a CT scan and 114 microGy for a lumbar spine radiograph to 2.2 mGy and 42 microGy, respectively, for an empty bladder.     

Current physical activity is related to bone mineral density in males but not in females

The purpose of the present study was to investigate the association between high-, medium-, and low-impact physical activity in males and females at the time of peak bone mineral density in young adulthood. The cohort consisted of 62 male medical students (aged 28.1 +/- 3.9) and 62 female medical students (aged 25.1 +/- 3.9). The bone mineral density (aBMD, g/cm (2)) of the total body, femoral neck, and lumbar spine, and the bone mineral content (BMC, grams) and area (cm (2)) of the femoral neck and lumbar spine was measured using dual energy X-ray absorptiometry. Volumetric BMD (vBMD, mg/cm (3)) of the femoral neck and lumbar spine was estimated. The total amount of physical activity per week, which was recorded in a questionnaire, was divided into high-impact, medium-impact, and low-impact activity. In the male cohort, hours of high-impact physical activity per week was associated with aBMD and BMC of all sites (r=0.27 - 0.53, p<0.05) and bone area of the femoral neck (r=0.38, p<0.01). Total amount of physical activity per week was associated with aBMD of the total body and femoral neck, BMC of femoral neck and lumbar spine, femoral neck vBMD, and the lumbar spine area (p<0.05 for all). Using multiple linear regression, high-impact physical activity was independently associated with aBMD (beta=0.27, p<0.05) and BMC (beta=0.34, p<0.01) of the femoral neck. In the female cohort there was no association between amount or type of physical activity to aBMD, BMC, vBMD, or the bone area of any site. Instead body weight, lean body mass, or fat mass were significantly related to aBMD and all BMC sites in this group. The results of the present study suggest that present physical activity level has a stronger relation to different aspects of bone mass in the male compared to the female adult skeleton.     

Exercise-induced training effects on bone mineral content: a 7-year follow-up study with adolescent female gymnasts and runners

The objective of this study was to assess differences in the effects of competitive gymnastics and running on bone mineral content (BMC) of the lumbar spine and femoral neck when compared with their non-competing age-matched controls. Caucasian healthy peri-pubertal girls (52 competing gymnasts, 46 competing runners, 44 non-athletic controls) were included. Weight, height, and type and amount of exercise (MET h/week) as well as BMC of the lumbar spine and femoral neck were measured repeatedly. Statistical comparisons between groups were made using ANOVA. Repeated measures were analyzed using generalized linear mixed models. The median MET value of gymnasts was significantly higher when compared with runners and controls at baseline, P =0.001. The weekly median MET hours decreased during the follow-up. The mean (adjusted for height, weight, and years from menarche in the 7-year follow-up) BMC of the lumbar spine and femoral neck was significantly higher among gymnasts when compared with the other two groups. Group-by-time interaction was significant only at the femoral neck ( P =0.048). The type of physical activity was a significant factor in BMC of the adolescent women. Gymnasts had greater BMC at lumbar spine and femoral neck during the total 7-year follow-up period when compared with runners and controls.     

Physical activity and bone mineral acquisition in peripubertal girls

The association of the amount and type of physical activity with bone mineral acquisition was studied in 191 peripubertal Caucasian girls aged 9-16 years (66 gymnasts, 65 runners, and 60 nonathletic controls). Weight, height, stage of puberty, the amount of leisure-time physical activity, and years of training were recorded, and dietary calcium and vitamin D were assessed by a semi-quantitative questionnaire. The bone area, the bone mineral density (BMD), and the bone mineral content (BMC) of the femoral neck, lumbar spine and antebrachium were measured by dual-energy x-ray absorptiometry. The unadjusted mean values of BMD at the femoral neck were 15.2% higher in the pubertal gymnasts than in the controls (P<0.001). Compared with the controls, the mean BMC adjusted for bone area of the pubertal gymnasts at the femoral neck and lumbar spine was 16.4% and 10.8% higher, respectively. When comparing the association of the type of physical activity among the pubertal athletics by multiple regression analysis, height, physical activity, gymnastics, and Tanner stage emerged as significant variables and accounted for 54.7% and 63.4% of the total variation in BMD of the femoral neck and lumbar spine, respectively. These results indicate that physical activity is associated with bone mineral acquisition in peripubertal girls and that high-impact weight-bearing exercise seems to be particularly associated with the increase of the BMD at the femoral neck.     

Comparative study of the performances of X-ray and gadolinium 153 bone densitometers at the level of the spine, femoral neck and femoral shaft

We investigated the precision of gadolinium 153 dual photon absorptiometry (DPA) and quantitative digital radiography (QDR) bone densitometers by determining in vitro and in vivo coefficients of variation (CV) of bone mineral density (BMD). In vitro, the long-term CV of spine phantom BMD measured weekly for 40 weeks was 1.2% and 0.7% for DPA and QDR, respectively. Stimulating soft-tissue thickness with water, the CV of 6 repeat measurements of spine phantom at depths from 0 to 27 cm in 1 cm steps (a total of 168 measurements) increased from 0.1% at 0 cm of water to 2.5% at 27 cm for DPA, and from 0.2% at 0 cm to 1.4% at 27 cm for QDR; mean CV of the 28 series (0-27 cm) was higher for DPA (1.2% +/- 0.8%, mean +/- SD) than for QDR (0.7% +/- 0.6%; P less than 0.001). With the hip phantom, femoral neck BMD was determined, and the CV was also dependent on water thickness; mean CV of the 20 series (0-10 cm) was 2.1% +/- 1.2% for DPA and 1.3% +/- 0.9% for QDR (not significant). In vivo, at the spine level, with DPA, mean CV of BMD measured 6 times after repositioning in 6 healthy volunteers was 3.8% +/- 1.9% and 2.1% +/- 0.7% with 153 Gd activity of 0.46 Ci and 1 Ci, respectively (BMD range: 0.796-1.247 g/cm2, no significant difference between the two groups).(ABSTRACT TRUNCATED AT 250 WORDS)     

Precision of regional bone mineral measurements obtained from total-body scans

Newer bone densitometers using dual-photon absorptiometry (DPA) or dual energy x-ray absorptiometry (DEXA) are capable of measuring the total-body bone mineral; regional analysis of these scans would have significant utility if adequate precision were possible. This study investigated short term precision by weekly scanning (three to five times) normal subjects (total 48 scans) and long term precision by scanning a whole-body phantom 30 times over 15 mo. For the 30 phantom scans, a coefficient of variation (CV) of bone mineral content (BMC) and bone mineral density (BMD) was calculated for each region. Nonrandom changes were analyzed by plotting the phantom data with time and testing the slope of the fitted line for significance. Similarly for the subjects, a CV for each region and the mean value for all subjects was obtained. From this study we conclude (a) BMD is more precise than BMC, (b) long-term precision was poorer than short term, (c) long-term regional BMD precision (%) was: head, 3.2; arms, 2.8; legs, 1.6; ribs, 2.6; pelvis, 3.8; thoracic spine, 3.8; lumbar spine, 7.1; total spine, 2.4; trunk, 2.2; total body, 1.2.