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PubMed1996

Correlation of ultrasound velocity in the tibial cortex, calcaneal ultrasonography, and bone mineral densitometry of the spine and femur.

We compared the attributes of tibial cortex speed of sound (SOS) measurements with the SOS and broadband ultrasound attenuation (BUA) of the calcaneus, and bone mineral densities of the lumbar spine and femoral neck in a patient crossover study. The three instruments used in the crossover study were the LUNAR DPX and AchillesTM, and a newly introduced device for measuring tibial cortical SOS, the SoundScanTM 2000. Ultrasound precision determinations on the two instruments were performed with the same group of 10 volunteers, and the bone densitometry precision was derived from 22 patients who were assessed twice in a single visit, with repositioning between spine and hip scans. There were 220 female patients in the clinical study, 28 of whom had thoracic spine fractures, and all had measurements with the three instruments. Of the three instruments, the best precision, or lowest coefficient of variation and standardized coefficient of variation, was obtained with the SoundScanTM 2000; 0.20% and 1.39%, respectively. The tibial SOS correlated more poorly with the lumbar spine and femoral neck bone mineral densities (BMDs) than the calcaneal parameters in 220 patients. Tibial SOS measurements could not distinguish the group with spinal fracture from an age-matched control group to a P < 0.05 level, whereas the lumbar spine BMD and calcaneal BUA and stiffness showed a significant difference. We conclude that the SoundScanTM 2000 system measures propagation of sound in the tibial cortex with great precision, but its role in clinical practice is moot. Yet to be established by a long-term prospective study is its efficacy in predicting fracture risk and how well it reflects bone change in response to treatment of osteoporosis.

Adult↗
PubMed1999

[CT densitometry for the grading of subcutaneous fibrosis after the photon-neutron therapy of malignant salivary gland tumors].

BACKGROUND: To evaluate alternative treatment regimen e.g. neutron therapy determination of treatment efficacy as well as side effects is important. Sensitivity of computed tomography (CT) in detecting changes of connective tissue after neutron therapy was examined. PATIENTS AND METHODS: In the course of their follow-up period (median 45 months) 12 patients with malignant salivary gland tumors who had postoperatively received neutron (1/12) or photon/neutron therapy (11/12) were examined by means of CT densitometry on 3 representative scans in the area of radiotherapy. In 3 ROI (regions of interest) in subcutaneous fatty tissue the density at the irradiated and the non-irradiated side was determined according to Hounsfield units (HU) and the average density was calculated. The average density of both sides was compared and correlated with the clinical grade of fibrosis according to LENT SOMA. RESULTS: All CT measurements (216 ROI, 18 ROI per patient) showed higher density levels on the irradiated side than on the non-irradiated side. The average density on the irradiated side was -57.7 +/- 4.7 HU and on the non-irradiated side -69.4 +/- 5.8 HU (p = 0.002). In 3/12 patients a clinical fibrosis was not seen; however, the relative density measured on the irradiated and non-irradiated side deviated by up to 8%. This could have been caused by minimal changes not being noticed by either patient and examiner. In patients with determined fibrosis Grade 1 (8/12) the relative density deviation was 4 to 39%. In 1/12 patients with determined fibrosis Grade 2 the relative density deviation was 50% (Figures 1a and 1b). Fibrosis Grade 3 and 4 did not occur (Table 1). CONCLUSIONS: Fibrosis is correlated with an increasing value of HU of the tissue density in CT. With the described method it is possible to graduate radiation induced subcutaneous fibrosis in correlation to the clinical fibrosis grade according to LENT SOMA. In the patients we examined subcutaneous fibroses after photon/neutron therapy were moderate. Especially in characterising subclinical or slight changes of connective tissue after radiotherapy computed tomography is of value.

Absorptiometry, Photon↗
PubMed2004

Evaluation of proposals of Belgian Social Security Institute for reimbursement of bone densitometry tests. Toward a cost-effective strategy for osteoporosis screening?

BACKGROUND AND AIMS: The Belgian Social Security Institute (hereafter INAMI) proposes a list of conditions to be considered as a prerequisite for reimbursement of Bone Mineral Density (BMD) measurements. The aim of this paper was to evaluate the diagnostic accuracy of the proposed criteria for identifying osteoporosis, and to gauge how useful they are for more rational application of densitometry tests. METHODS: 3748 Caucasian women aged at least 50 years old were recruited consecutively from an outpatient university center, from the database of which all relevant data corresponding to the INAMI list of clinical factors, as well as patients' age, weight and height, were collected. BMD measurements using dual X-ray absorptiometry were reported at the spine and hip regions. Diagnostic accuracy was evaluated through measures of sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Additionally, from ROC analysis, benchmark values for age and body mass index were identified and then, used alone and in combination with the INAMI test, were applied to define various screening strategies. For each of them, associated costs per osteoporotic patient detected were estimated. Cost estimates refer only to the costs associated with the densitometric procedure from the perspective of the reimbursement health authorities. RESULTS: Applying INAMI criteria for detecting osteoporosis at any of the considered sites yielded sensitivity of 68.9%, specificity of 50.7%, PPV of 42.9% and NPV of 57.3%. Comparison of incremental costs per patient of the different strategies revealed that, with 67.1 Euros, the option of opening BMD coverage to women on the basis of the INAMI conditions would be more cost-effective than mass screening (90.1 Euros) or applying the age criterion alone (70.2 Euros). However, the BMI condition seems to act as a better indicator of risk than the INAMI criteria in those meeting the age condition (35.4 Euros). CONCLUSIONS: The accuracy of the INAMI proposal turns out to be quite unsatisfactory, and did not adequately cover the population at risk of osteoporosis. From a resource allocation perspective, the best strategy by far would be to recommend using concomitantly INAMI, age and BMI-selective criteria. Some adaptations could enhance the usefulness of the INAMI proposals as a selective approach for BMD referral and reimbursement.

Absorptiometry, Photon↗
PubMed1996

[Diagnosis of osteoporosis with ultrasound densitometry of the calcaneus].

PURPOSE: We evaluated the speed of sound (SOS) and broadband ultrasound attenuation (BUA) at the os calcis as an indicator of osteoporosis and observed the age-related changes in ultrasound values in normal women. MATERIALS AND METHODS: BUA and SOS were measured in 236 women using the "Achilles" densitometer (Lunar, Madison, Ohio). From the BUA and SOS values the BUA/SOS Index ("Stiffness" Index) is calculated. We investigated 55 female patients with osteoporosis (aged 43-85 years) and 181 healthy women (aged 20-80 years). RESULTS: Ultrasound values for women with osteoporosis were significantly lower than those for the normal control group. The Z-score compared with young normals was higher for the BUA/SOS Index (-3.1) than for BUA (-2.5) and SOS (-3.0). At a BUA/SOS Index of 68 the sensitivity was 85 %, and the specificity was 77 % for patients with osteoporotic fractures. We found a significant decline with age in SOS (r = -0.55), BUA (r = -0.50) and BUA/SOS Index (r = -0.57). CONCLUSION: Ultrasound bone densitometry at the os calcis can be used as a screening test in the diagnosis of osteoporosis.

Adult↗
PubMed2003

Phalangeal quantitative ultrasound technology and dual energy X-ray densitometry in patients with primary hyperparathyroidism: influence of sex and menopausal status.

Fifty-one patients with surgically proven primary hyperparathyroidism (PHPT), 11 males and 40 females, mean age+/-SD: 55.9+/-14.1 years, and 58 age- and sex-matched normal subjects were studied. The femoral and L(2)-L(4) bone mineral density (BMD; Hologic QDR 4500 C), as well as quantitative ultrasonometry (QUS; DBM-Sonic 1200) of the phalanges of both hands were measured in patients and controls. QUS measurements included amplitude-dependent speed of sound (AD-SoS), and other parameters derived from the graphic trace: signal dynamics (Sdy), first wave amplitude (FWA), bone transmission time (BTT) and ultrasound bone profile index (UBPI). Patients with PHPT showed significantly lower dual energy X-ray densitometry (DXA) values and QUS parameters compared to controls (lumbar spine Z-score: controls: -0.16+/-1.12, PHPT: -0.70+/-1.14, P=0.016; femoral neck Z-score: controls: -0.28+/-1.74, PHPT: -1+/-1.01, P=0.013; total femur Z-score: controls: -0.33+/-1.12, PHPT: -1.01+/-0.95, P=0.0013; AD-SoS Z-score: controls: -0.89+/-1.22, PHPT: -1.97+/-1.78, P=0.0003; FWA Z-score: controls: 0.36+/-1, PHPT: 0.62+/-0.85, P<0.0001; BTT Z-score: controls: 0.04+/-1.03, PHPT: -0.45+/-1.37, P=0.044; UBPI Z-score: controls: -0.02+/-1.01, PHPT: -0.68+/-1.05, P=0.002; SDy (mV/micros(2)): controls: -295+/-256, PHPT: -498+/-306, P=0.0003). In male patients, BMD values measured on the lumbar spine and femoral regions were similar to those found in male controls, while QUS values were significantly lower (lumbar spine Z-score: controls: -1.05+/-1.41, PHPT: -1.75+/-1.21, P=0.21; femoral neck Z-score: controls: -0.37+/-1.84, PHPT: -1.11+/-1.14, P=0.27; total femur Z-score: controls: -0.16+/-1.59, PHPT: -1.02+/-1.20, P=0.168; AD-SoS Z-score: controls: -0.52+/-1.58, PHPT: -1.57+/-1.77, P=0.149; FWA Z-score: controls: 0.67+/-1.01, PHPT: -0.74+/-0.79, P=0.0016; BTT Z-score: controls: 1.22+/-0.83, PHPT: 0.75+/-1.51, P=0.478; UBPI Z-score: controls: 0.56+/-0.94, PHPT: -0.47+/-1.10, P=0.025; SDy (mV/micros(2)): controls: -167+/-230, PHPT: -485+/-307, P=0.01). Women with PHPT were further divided into two subgroups: premenopause ( n=11) and postmenopause ( n=29). The premenopausal women with PHPT showed significantly lower DXA values than those of the premenopausal control ones, but similar QUS parameters (lumbar spine Z-score: controls: 0.12+/-0.66, PHPT: -0.59+/-0.85, P=0.03; femoral neck Z-score: controls: 0.06+/-2.85, PHPT: -1.48+/-1.05, P=0.11; total femur Z-score: controls: -0.51+/-0.97, PHPT: -1.48+/-0.63, P=0.009; AD-SoS Z-score: controls: 0.78+/-0.89, PHPT: -1.26+/-1.88, P=0.42; FWA Z-score: controls: 1.14+/-0.77, PHPT: 0.12+/-0.80, P=0.007; BTT Z-score: controls: 0.13+/-0.60, PHPT: 0.25+/-1.15, P=0.757; UBPI Z-score: controls: 0.73+/-0.49, PHPT: 0.24+/-0.96, P=0.15; SDy (mV/micros(2)): controls: -118+/-123, PHPT: -271+/-301, P=0.106). The postmenopausal women with PHPT showed both DXA and QUS parameters significantly lower than those found in the postmenopausal controls (lumbar spine Z-score: controls: 0.09+/-0.96, PHPT: -0.31+/-0.96, P=0.004; femoral neck Z-score: controls: -0.38+/-1.01, PHPT: -0.76+/-0.91, P=0.14; total femur Z-score: controls: -0.33+/-0.97, PHPT: -0.81+/-0.92, P=0.057; AD-SoS Z-score: controls: -1.08+/-1.17, PHPT: -2.38+/-1.68, P=0.31; FWA Z-score: controls: -0.013+/-0.81, PHPT: -0.86+/-0.74, P=0.0009; BTT Z-score: controls: -0.58+/-0.68, PHPT: -1.13+/-0.93, P=0.016; UBPI Z-score: controls: -0.62+/-0.83, PHPT: -1.11+/-0.82, P=0.034; SDy (mV/micros(2)): controls: -419+/-242, PHPT: -589+/-269, P=0.012). The relative risk of osteopenia was significantly increased in PHPT patients at several measurement sites. There was a highly significant correlation between spine and femoral BMD and QUS parameters, while PTH serum levels did not correlate with any of the densitometric variables. In conclusion, QUS parameters would seem to be able to distinguish patients with PHPT from normal controls in male subjects and in postmenopausal women, but not in premenopausal women. This would suggest that the higher estrogen levels in premenopausal patients might preserve the bone from significant structural changes. This may also suggest that hyperparathyroidism, in addition to the reduction of bone mineral content, can cause an alteration of bone structure with an additional increase in fracture risk in postmenopausal women. Furthermore, the alterations in QUS parameters in patients who do not show significant changes in DXA measurements suggest an involvement of bone that is independent of mineral content and may be helpful for selecting candidates for surgery, according to NIH criteria.

Absorptiometry, Photon↗
PubMed2003

Which bone densitometry and which skeletal site are clinically useful for monitoring bone mass?

Long-term precision, as well as reproducibility, is important for monitoring bone mineral density (BMD) alteration in response to aging or therapy. In order to investigate which bone densitometry and which skeletal site are clinically useful for monitoring bone mass, we examined the standardized long-term precision of several bone density measurements in 83 healthy Japanese women. Annual BMD measurements were performed for 5 or 6 years using dual X-ray absorptiometry (DXA) on the lumbar spine, radius (EXP5000) and calcaneus (HeelScan); peripheral quantitative computed tomography (pQCT) on the radius (Densiscan1000); and quantitative ultrasound (QUS) on the calcaneus (Achilles+). The long-term precision error for the individual subject was given by the standard error of estimate (SEE), and the standardized long-term precision was defined as the percentage coefficient of variation (CV%) divided by the percentage ratio of the annual bone-loss rate. Based on the CV% of spinal DXA, speed of sound (SOS) and diaphyseal pQCT showed significantly higher precision than others, while radial ultradistal (UD) DXA and heel DXA showed significantly lower precision. The long-term precision errors of other measurements were statistically the same as that of the spinal DXA. The spinal DXA, the radial DXA, and pQCT at both the distal metaphysis and diaphysis showed high rates of annual bone loss. The radial trabecular BMD (pQCT) was significantly higher than that of spinal DXA. The annual rates of bone loss of QUS and of heel DXA were significantly lower than that of spinal DXA. Taken together, standardized long-term precision was obtained in the spinal DXA and radial pQCT. In conclusion, spinal DXA and radial pQCT were considered the most useful monitoring method for osteoporosis, while QUS was considered less useful.

Absorptiometry, Photon↗
PubMed2005

Correlation between patient recall of bone densitometry results and subsequent treatment adherence.

Treatment of osteoporosis is often inadequate. One reason can be insufficient patient education following diagnostic bone densitometry (DXA). Therefore, we studied how patients are informed and treated following their first DXA. Individuals who had DXA at a rural hospital in Wisconsin were surveyed with a questionnaire regarding their post-test education and prescribed treatment. Their DXA results and the specialty of their clinician were also recorded. Eighty percent of the 1,014 participants were informed of their results. Of the 341 participants who had normal bone mineral density (BMD), 63% reported correct results, while only 31% of the 309 who had osteopenia and 50% of the 364 who had osteoporosis reported correct results. Accuracy in reporting was not affected by the patients' age or the specialty of their clinicians. Following DXA, 339 patients (33%) were started on medications; 86% of those remained on some prescribed therapy for osteoporosis, but 140 (41%) did not continue the initial medication. Reasons for discontinuation included side effects (48%) and cost (26%). Patients with low BMD who correctly reported their results were more likely to have received a medication and to continue to take it ( p <0.0001). Calcium supplements were recommended to 65% of those not taking calcium prior to DXA. Internists were more likely than family practitioners to recommend calcium, and their patients reported better medication adherence, as did those with osteoporosis compared with osteopenia. We conclude that, while most participants are informed of the results of their DXAs, the retained information may not be accurate. Correct understanding of DXA results may lead to higher treatment rates and better adherence to treatment among patients with low BMD.

Absorptiometry, Photon↗
PubMed2005

Osteoporosis case finding in the general practice: phalangeal radiographic absorptiometry with and without risk factors for osteoporosis to select postmenopausal women eligible for lumbar spine and hip densitometry.

Mass screening for osteoporosis using DXA measurements at the spine and hip is presently not recommended by health authorities. Instead, risk factor questionnaires and peripheral bone measurements may facilitate the selection of women eligible for axial bone densitometry. The aim of this study was to validate a case finding strategy for postmenopausal women who would benefit most from subsequent DXA measurement by using phalangeal radiographic absorptiometry (RA) alone or in combination with risk factors in a general practice setting. The sensitivity and specificity of this strategy in detecting osteoporosis (T-score < or =2.5 SD at the spine and/or the hip) were compared with those of the current reimbursement criteria for DXA measurements in Switzerland. Four hundred and twenty-three postmenopausal women with one or more risk factors for osteoporosis were recruited by 90 primary care physicians who also performed the phalangeal RA measurements. All women underwent subsequent DXA measurement of the spine and the hip at the Osteoporosis Policlinic of the University Hospital of Berne. They were allocated to one of two groups depending on whether they matched with the Swiss reimbursement conditions for DXA measurement or not. Logistic regression models were used to predict the likelihood of osteoporosis versus "no osteoporosis" and to derive ROC curves for the various strategies. Differences in the areas under the ROC curves (AUC) were tested for significance. In women lacking reimbursement criteria, RA achieved a significantly larger AUC (0.81; 95% CI 0.72-0.89) than the risk factors associated with patients' age, height and weight (0.71; 95% C.I. 0.62-0.80). Furthermore, in this study, RA provided a better sensitivity and specificity in identifying women with underlying osteoporosis than the currently accepted criteria for reimbursement of DXA measurement. In the Swiss environment, RA is a valid case finding tool for patients with risk factors for osteoporosis, especially for those who do not qualify for DXA reimbursement.

Absorptiometry, Photon↗
PubMed2006

An audit of bone densitometry practice with reference to ISCD, IOF and NOF guidelines.

INTRODUCTION: The impact of osteoporosis guidelines on clinical practice has not been fully evaluated. OBJECTIVES: To estimate the positive predictive value (PPV) of the National Osteoporosis Foundation (NOF), the International Osteoporosis Foundation (IOF) and the International Society for Clinical Densitometry (ISCD) guidelines for osteoporosis and compare it to the PPV of clinical judgement alone. METHODS: All subjects tested for bone mineral density during the fall of 2001 in three teaching hospitals in Beirut were invited to participate. The reference databases used for the calculation of the T-score were the NHANES database for the hip and the manufacturer's database for the spine. The impact of using guidelines was measured by the increment in PPV. Osteoporosis was defined as a T-score < or =-2.5 at either the spine or hip. RESULTS: A total of 307 post-menopausal women were tested with dual-energy X-ray absorptiometry (DXA). In current practice (clinical judgement alone), the PPV for osteoporosis was 42.4%; using NOF guidelines, 236 women would have been tested, and the PPV would have been 46.2%. Similarly, using IOF or ISCD guidelines, 236 women would have been tested, and the PPV would have been 47.1%. CONCLUSION: Compared to current clinical practice, application of the ISCD, IOF and NOF guidelines may increase the predictive value of a central DXA for osteoporosis.

Absorptiometry, Photon↗
PubMed1999

Forearm bone mineral densitometry cannot be used to monitor response to alendronate therapy in postmenopausal women.

Alendronate significantly increases bone mass and reduces hip and spine fractures in postmenopausal women. To determine whether forearm densitometry could be used to monitor the efficacy of alendronate, we examined changes in bone mineral density (BMD) at the forearm (one-third distal, mid-distal, ultradistal radius) versus changes at the hip (femoral neck, total hip) and spine (posteroanterior and lateral) in a double-masked, randomized, placebo-controlled clinical trial of 120 elderly women (mean age 70 +/- 4 years) treated with alendronate for 2.5 years. We found that among women in the treatment group, BMD increased by 4.0-12.2% at the hip and spine sites (all p<0.001), whereas BMD increased only nominally at the one-third distal radius (1.3%, p<0.001) and mid-radius (0.8%, p<0.05), and remained stable at the ultradistal radius. At baseline, forearm BMD correlated with that of the hip (r = 0.55-0.64, p<0.001), femoral neck (r = 0.54-0.61, p<0.001) and posteroanterior spine (r = 0.56-0.63, p<0.001). Changes in radial BMD after 1 year of therapy were not correlated with changes in hip and spine BMD after 2.5 years of therapy. In contrast, short-term changes in total hip and spine BMD were generally positively associated with long-term changes in total hip, femoral neck and spine BMD (r = 0.30-0.71, p<0.05). Furthermore, long-term BMD changes at the forearm did not correlate with long-term hip and spine BMD changes, in contrast to the moderate correlations seen between spine and hip BMD at 2.5 years (r = 0.38-0.45, p<0.01). We conclude that neither short- nor long-term changes in forearm BMD predict long-term changes in overall BMD for elderly women on alendronate therapy, suggesting that measurements of clinically relevant central sites (hip and spine) are necessary to assess therapeutic efficacy.

Absorptiometry, Photon↗
PubMed1997

Ultrasound bone densitometry of os calcis in elderly Japanese women with hip fracture.

We evaluated 138 elderly patients (mean age 79 years) within 2 weeks after hip fracture (67 cervical and 71 trochanteric) using an Achilles ultrasound bone densitometer (Lunar Corporation, Madison, WI). The ultrasound variables of speed of sound (SOS in m/second), broadband ultrasound attenuation (BUA in dB/MHz), and stiffness (%) index were measured on the os calcis. Ultrasound densitometry also was done on 563 normal postmenopausal women to assess normal age changes. An elderly subgroup (n = 138) served as age-matched controls for the hip fracture group. Further subgroups of 33 patients and 33 controls were compared for lumbar spine and femoral neck BMD. There were no statistically significant differences between the hip fracture group and age-matched controls in height and weight, but each ultrasound variable was significantly lower for the hip fracture group (P < 0.0001). For the hip fracture group, SOS was 1470 +/- 19 m/second, BUA was 84.3 +/- 8.4 dB/MHz, and the stiffness index was 47.8 +/- 9.2%, whereas for the age-matched controls, SOS was 1486 +/- 27 m/second, BUA was 94.0 +/- 11.4 dB/MHz, and the stiffness index was 59.1 +/- 12.5%. There were no significant differences between cervical and trochanteric hip fracture groups. Logistic regression analysis showed that a change of the ultrasound values by 1 standard deviation (SD) changed the odds ratio for SOS, BUA, and stiffness index by 2.51, 3.24, and 3.60, respectively. Ultrasound variables, particularly stiffness, were good indicators of hip fracture risk.

Aged↗
PubMed2006

Relationship between CT densitometry with a slice thickness of 0.5 mm and audiometry in otosclerosis.

The appropriate cutoff Hounsfield unit (HU) value for the diagnosis of otosclerosis was determined and the correlation between the bone conduction threshold and the findings of computed tomography (CT) densitometry investigated. CT images, 0.5-mm thick, were evaluated in 24 ears with otosclerosis and 19 control ears. Eight regions of interest were set around the otic capsule. The mean HU values in the area anterior to the oval window (A-OW) and anterior to the internal auditory canal (A-IAC) were significantly lower in otosclerosis than in controls. Based on receiver operating characteristic (ROC) analysis, the cutoff HU value in A-OW was determined to be 2,187.3 HU. The mean HU value in retrofenestral otosclerosis was significantly lower in the area A-OW, A-IAC and around the cochlea than in controls. Based on ROC analysis, the cutoff HU value in the latter was determined to be 2,045 HU. A statistically significant correlation was found between the density of the area A-OW and the hearing level at 500 and 1,000 Hz, and between the density of the area around the cochlea and the hearing level at most frequencies. These results suggest the semi-automated diagnosis of otosclerosis may be possible.

Absorptiometry, Photon↗
PubMed2001

Using bone densitometry to monitor therapy in treating osteoporosis: pros and cons.

Measurement of bone density is crucial for evaluating fracture risk. Low bone mass is a powerful predictor of fracture and is necessary to assess the need for treatment. Dual energy x-ray absorptiometry is accurate and precise. Use of bone density for monitoring therapy is an important tool for evaluating response to therapy, but an understanding of the limitations of the procedure are important for the practicing physician. Precision error of the technology and what change in density is clinically significant (least significant change) are important concepts to interpret results and make appropriate treatment decisions. This article reviews the use of bone densitometry as a tool for monitoring treatment in patients with low bone mass.

Absorptiometry, Photon↗
PubMed1992

Bone densitometry in patients with multiple myeloma.

PURPOSE, PATIENTS, AND METHODS: We performed dual-energy x-ray absorptiometry in 10 selected patients with aggressive multiple myeloma in whom substantial tumor mass reduction was achieved after high-dose chemoradiotherapy followed by autologous blood stem cell transplantation. RESULTS: In most cases, bone mineral density (BMD) of the spine was initially low (Mean Z score: -2.69, SEM 0.76) and dramatically increased after treatment (mean increase 16.4%; 7.7% with 95% confidence interval 2.2 to 12.2, excluding one patient whose spine BMD increased by 94.8%). In contrast, skeletal roentgenograms, computed tomographic scans, and magnetic resonance imaging did not reveal any significant improvement of patients' bone lesions. CONCLUSIONS: In patients with multiple myeloma, bone densitometry could be a useful way to assess the efficacy of treatment on bone status.

Absorptiometry, Photon↗
PubMed1994

Quantitative analysis of quaternary ammonium antiseptics using thin-layer densitometry.

A thin-layer chromatography method for quantitative analysis of quaternary ammonium antiseptics is described. Silanized silica gel was used as the stationary phase. The mobile phase consisted of methanol-25% (m/v) sodium acetate solution-acetone (65:35:20). The method is able to separate the chain homologues of benzalkonium chloride, cetylpyridinium chloride and cetrimide. Detection was performed using a colour reaction with potassium triiodide solution. The different homologues were quantified using UV densitometry at 400 nm. A number of commercial samples was analysed using this method. From the results it appears that it is worthwhile to have a limit test for the composition of quaternary ammonium antiseptics in pharmacopoeial monographs, the more so as the antibacterial activity depends on it.

Acetates↗
PubMed1992

Demonstration of calcitonin gene-related peptide receptors in the gubernaculum by computerized densitometry.

The gubernaculum appears to guide inguinoscrotal testicular descent by migration into the scrotum ahead of the testis. Calcitonin gene-related peptide (CGRP) has been found in the scrotal branches of the genitofemoral nerve of neonatal rats, and is known to stimulate gubernacular motility in vitro. This study aimed to identify CGRP receptors in the gubernaculum, which should be present if CGRP mediates gubernacular migration toward the scrotum. Gubernacular sections from neonatal male rats were incubated with [125I]-human CGRP as well as a variety of unlabeled neuropeptides. By using computerized densitometry, the quantitation of CGRP binding derived from in vitro autoradiography demonstrated a distinctive distribution of binding sites for CGRP over the developing cremasteric muscle in the gubernaculum. The binding analysis showed a single class of sites with a dissociation constant (Kd) of 2.13 nmol/L and a receptor density of 27.4 fmol/mg polymer. These results endorse the hypothesis that CGRP released from the nerve acts directly on the cremaster via its own receptors, which have not been described previously.

Absorptiometry, Photon↗
PubMed1992

Non-invasive densitometry.

Several non-invasive methods are available to measure bone density in different regions of the skeleton. Bedrest and microgravity both lead to bone loss, which is more marked in the lower parts of the skeleton. The bone loss can be monitored by non-invasive techniques in longitudinal studies when precision (i.e. the ability to produce repeated measurements with the same value) is adequate. Bone mineral density (BMD) can be measured with single photon absorptiometry in the lower forearm and calcaneus and with dual energy X-ray absorptiometry (DXA) in almost any region of the skeleton. The latter technique pairs good precision with very low radiation exposure. With peripheral quantitative computed tomography very precise measurements of the lower forearm and tibia are feasible with low radiation dose. It has the additional option of separate measurement of cortical and trabecular bone. This could be of particular importance in microgravity studies, as trabecular bone loss is more severe in this condition. A new development is the measurement of ultrasound velocity or attenuation which depends on bone density and structure. Ultrasound data of the calcaneus correlate well with bone mineral density in spine and hip. The advantage of this technique is that it operates without radiation. However, the clinical value has to be established. The ultimate choice of technique and skeletal region for bone densitometry will depend on specific requirements.

Absorptiometry, Photon↗
PubMed1991

Trabecular bone densitometry using interactive image analysis.

Interactive image analysis is a novel application of digital image processing to the densitometry of trabecular bone. Briefly, the exposed surfaces of bleached slices of bone are illuminated so that the trabecular tips are bright in relation to the interstices. The image is then captured by a TV camera and digitized with an interactive image analysis system. A grey scale is then chosen that differentiates the bone at the surface from the background. Finally, a computer program calculates the area fraction of bone within a user-specified box which, by Delesse's principle, is an estimate of the volume fraction of bone. The reproducibility of the technique (expressed as an average SD) is +/- 1.5 vol. % and has surface-discriminating capabilities comparable to the traditional point-counting method but is faster and more precise. Most importantly, the technique permits biomechanical testing of the sample after its density has been determined.

Aged↗