Biomedical subjects

H K Genant

Publications and source records attributed to H K Genant.

At least 55 records · Page 3Linked to original sources

PubMed2001

Fully automated software to monitor wear in prosthetic knees using fluoroscopic images.

Total knee arthroplasty is now a widely accepted treatment for late-stage arthritis. Wear of the polyethylene layer in prosthetic knees is a known cause of implant failure. Early detection of wear may allow prediction of device failure. In this paper we describe a fully automated image processing algorithm to measure the minimum tibiofemoral joint space width (mJSW) for monitoring prosthesis wear radiographically. The femoral portion and tibial plate were automatically delineated and mJSW was calculated in each compartment. The software also delineated the tip of the prosthesis pin in order to make a magnification correction. The algorithm was tested with a set of triplicate acquisitions of 18 fluoroscopic knee images. The RMS standard deviation (RMSSD) for the triplicate measurements was calculated as a figure of merit. The RMSSD was 0.077 and 0.087 mm for the lateral and medial compartments. The computer successfully found the minimum JSW for both compartments in all 54 images. A single case (2% of total) required user interaction to correct for an obvious failure to delineate the prosthesis pin. We document a robust and precise tool for quantifying mJSW to monitor prosthesis wear.

Algorithms↗

PubMed2001

Assessment of bone status using speed of sound at multiple anatomical sites.

Studies in vitro and in vivo have shown that quantitative ultrasound (QUS) is a valid tool for the assessment of bone status. Current QUS methods using the transmission technique are limited to one peripheral bone site. A new system, Sunlight Omnisense (Omnisense, Sunlight Medical Ltd., Rehovot, Israel), measures speed of sound (SOS, in m/s) along the surface of the bone based on an axial transmission technique. The Omnisense can measure SOS at several anatomical sites. This study evaluated the SOS at different anatomical sites in a healthy population. A total of 334 adult women from three research centers in the USA and Canada with a mean (+/- SD) age of 48.8 (+/- 17.4) years were enrolled in this study. SOS was measured at the proximal third phalanx, distal one third radius, midshaft tibia, and fifth metatarsal. The mean SOS (+/- SD) values for the phalanx, radius, tibia and metatarsal were 3984 (+/- 221), 4087 (+/- 147), 3893 (+/- 150) and 3690 (+/- 246) m/s, respectively. Each anatomical site SOS was significantly different (p < 0.001) from that of the other sites. SOS at the different anatomical sites was modestly, but significantly, correlated (r = 0.31 to 0.56, p < 0.001). Similar correlation coefficients were obtained for the T scores. The mean T scores for subjects over the age of 60 years were -1.94, -2.01, -0.97 and -1.42 for the phalanx, radius, tibia and metatarsal, respectively. The age of peak SOS and the rate of change thereafter varied with anatomical site, implying that the prevalence of osteopenia and osteoporosis was site-dependent if only one T score cut-off point was used. Comparing individuals, 10% to 17% of patients had T scores that differed by more than a factor of 2 between sites. Weight and age were some of the contributing factors to this heterogeneity. The Omnisense provides an opportunity to assess bone status at different anatomical sites. Whether or not combining measurements from all these anatomical sites will improve osteoporosis management still needs to be determined.

Adult↗

PubMed2001

Interleukin-1 receptor antagonist treatment of rheumatoid arthritis patients: radiologic progression and correlation of Genant/Sharp and Larsen scoring methods.

OBJECTIVE: The Genant/Sharp scoring method is a validated radiologic scoring system useful for diagnosing, classifying, and defining specific clinical problems associated with rheumatoid arthritis (RA). The Genant/Sharp scoring method is described, and its level of correlation with the Larsen scoring method is discussed. METHOD: The Genant/Sharp scoring system evaluates erosion, joint space narrowing (JSN), and a combination of erosion and JSN referred to as the total score. This method was used to determine change in radiographic progression during 2 consecutive 6-month intervals within a multicenter, double-blind, placebo-controlled study of recombinant human interleukin-1 receptor antagonist (IL-1ra) in patients with RA. These results were compared with the results obtained through the Larsen scoring method to determine their correlation. RESULTS: The Genant/Sharp scoring method showed a moderate correlation with the Larsen scoring method, particularly at baseline, and showed similar treatment trends in a study of IL-1ra in patients with RA. CONCLUSION: The Genant/Sharp scoring method provides an alternative to the Sharp and Larsen approaches for radiographic assessment in RA.

Arthritis, Rheumatoid↗

PubMed2001

Automated measurement of radiographic hip joint-space width.

Radiographic joint-space narrowing (JSN) is the principle indicator of cartilage loss in osteoarthritis (OA). JSN is usually assessed qualitatively by visual inspection or in clinical research, is measured manually with a graduated handheld lens directly applied to the x-ray film, or from digitized radiographs by hand tracing the joint margins with a mouse. The minimum joint-space width (mJSW) and joint-space area (JSA) are recorded as the indices of OA progression in epidemiological studies and clinical drug trials. We present a computerized method that automatically finds the articular margins of the hip to improve determination of mJSW and JSA. The algorithm requires that three seed points are manually identified on the femoral head and uses three steps to process each digitized hip x-ray. First, a Hough transform finds the center and radius (R) of a circle that approximates the femoral head. Finding R indicates whether magnification differences must be corrected on repeat exams. Second, a gradient algorithm finds the edge of the femoral head and acetabulum. Third, the mid-line of the femoral neck is automatically found and used to define the joint portion (theta) that is assessed for narrowing. theta is fixed for follow-up exams of the same subject. The algorithm was evaluated in three ways to determine its performance characteristics. First, the inter-reader and intra-reader variability for mJSW and JSA associated with the selection of the seed points was found to be negligible (< 1%) compared to the variability associated with manual scoring with a lens or by tracing the joint margins with a mouse. Second, from duplicate hip x-rays of 19 subjects with OA, the Root Mean Square Standard Deviation and coefficient of variation for mJSW and JSA defined by the algorithm was determined to be better than manual techniques by at least a factor of 2. Third, the algorithm correctly identified the joint margin in more than 85% of the 105 cases tested. Automated measures of radiographic hip joint-space narrowing is less subjective than manual methods and may be applicable for monitoring OA progression in clinical research.

Acetabulum↗

PubMed2001

Effects of current and discontinued estrogen replacement therapy on hip structural geometry: the study of osteoporotic fractures.

It is assumed that estrogen influences bone strength and risk of fractures by affecting bone mineral density (BMD). However, estrogen may influence the mechanical strength of bones by altering the structural geometry in ways that may not be apparent in the density. Repeated dual energy X-ray absorptiometry (DXA) hip scan data were analyzed for bone density and structural geometry in elderly women participating in the Study of Osteoporotic Fractures (SOF). Scans were studied with a hip structural analysis program for the effects of estrogen replacement therapy (ERT) on BMD and structural geometry. Of the 3,964 women with ERT-use data, 588 used ERT at both the start and end of the approximately 3.5-year study, 1,203 had past use which was discontinued by clinic visit 4, and 2,163 women had never used ERT. All groups lost BMD at the femoral neck, but the reduced BMD among users of ERT was entirely due to subperiosteal expansion and not bone loss, whereas both bone loss and expansion occurred in past or nonusers. BMD increased 0.8%/year at the femoral shaft among ERT users but decreased 0.8%/year among nonusers. Section moduli increased at both the neck and shaft among ERT users but remained unchanged in past and nonusers. Current, but not past, use of estrogen therapy in elderly women seems to increase mechanical strength of the proximal femur by improving its geometric properties. These effects are not evident from changes in femoral neck BMD.

Aged↗

PubMed2001

Classification of osteoporosis based on bone mineral densities.

In this article we examine the role of bone mineral density (BMD) in the diagnosis of osteoporosis. Using information from 7671 women in the Study of Osteoporotic Fractures (SOF) with BMD measurements at the proximal femur, lumbar spine, forearm, and calcaneus, we examine three models with differing criteria for the diagnosis of osteoporosis. Model 1 is based on the World Health Organization (WHO) criteria using a T score of -2.5 relative to the manufacturers' young normative data aged 20-29 years, with modifications using information from the Third National Health and Nutrition Examination Survey (NHANES). Model 2 uses a T score of -1 relative to women aged 65 years at the baseline of the SOF population. Model 3 classifies women as osteoporotic if their estimated osteoporotic fracture risk (spine and/or hip) based on age and BMD is above 14.6%. We compare the agreement in osteoporosis classification according to the different BMD measurements for the three models. We also consider whether reporting additional BMD parameters at the femur or forearm improves risk assessment for osteoporotic fractures. We observe that using the WHO criteria with the manufacturers' normative data results in very inconsistent diagnoses. Only 25% of subjects are consistently diagnosed by all of the eight BMD variables. Such inconsistency is reduced by using a common elderly normative population as in model 2, in which case 50% of the subjects are consistently diagnosed as osteoporotic by all of the eight diagnostic methods. Risk-based diagnostic criteria as in model 3 improve consistency substantially to 68%. Combining the results of BMD assessments at more than one region of interest (ROI) from a single scan significantly increases prediction of hip and/or spine fracture risk and elevates the relative risk with increasing number of low BMD subregions. We conclude that standardization of normative data, perhaps referenced to an older population, may be necessary when applying T scores as diagnostic criteria in patient management. A risk-based osteoporosis classification does not depend on the manufacturers' reference data and may be more consistent and efficient for patient diagnosis.

Adult↗

PubMed2001

Structural adaptation to changing skeletal load in the progression toward hip fragility: the study of osteoporotic fractures.

Longitudinal, dual-energy X-ray absorptiometry (DXA) hip data from 4187 mostly white, elderly women from the Study of Osteoporotic Fractures were studied with a structural analysis program. Cross-sectional geometry and bone mineral density (BMD) were measured in narrow regions across the femoral neck and proximal shaft We hypothesized that altered skeletal load should stimulate adaptive increases or decreases in the section modulus (bending strength index) and that dimensional details would provide insight into hip fragility. Weight change in the approximately 35 years between scan time points was used as the primary indicator of altered skeletal load. "Static" weight was defined as within 5% of baseline weight, whereas "gain" and 'loss" were those who gained or lost >5%, respectively. In addition, we used a frailty index to better identify those subjects undergoing changing in skeletal loading. Subjects were classified as frail if unable to rise from a chair five times without using arm support. Subjects who were both frail and lost weight (reduced loading) were compared with those who were not frail and either maintained weight (unchanged loading) or gained weight (increased loading). Sixty percent of subjects (n = 2,559) with unchanged loads lost BMD at the neck but not at the shaft, while section moduli increased slightly at both regions. Subjects with increasing load (n = 580) lost neck BMD but gained shaft BMD; section moduli increased markedly at both locations. Those with declining skeletal loads (n = 105) showed the greatest loss of BMD at both neck and shaft; loss at the neck was caused by both increased loss of bone mass and greater subperiosteal expansion; loss in shaft BMD decline was only caused by greater loss of bone mass. This group also showed significant declines in section modulus at both sites. These results support the contention that mechanical homeostasis in the hip is evident in section moduli but not in bone mass or density. The adaptive response to declining skeletal loads, with greater rates of subperiosteal expansion and cortical thinning, may increase fragility beyond that expected from the reduction in section modulus or bone mass alone.

Absorptiometry, Photon↗

PubMed2001

Multisite bone ultrasound measurement on North American female reference population.

The Sunlight Omnisense is a portable quantitative ultrasound device that measures speed of sound (SOS) at multiple skeletal sites and therefore has the potential to provide a more complete assessment of an individual's overall fracture risk than single-site measurements such as the calcaneus. To provide a robust normative female database, 545 healthy Caucasian women ages 20-90 were recruited at five centers across North America. SOS measurements were obtained from the distal one-third radius, proximal third phalanx, midshaft tibia, and fifth metatarsal. The results demonstrate that peak SOS occurs around the age of 40, with maximum mean values of 4161, 3928, 3786, and 4092 m/s seen at the radius, tibia, metatarsal, and phalanx, respectively. Maximal rate of decline of SOS was seen in the decade following menopause (-12.4, -9.2, -12.1, and -18.8 m/s at the radius, tibia, metatarsal, and phalanx, respectively). Reproducibility between successive measurements indicates high precision, with standardized coefficients of variance ranging between 1.5 and 4.5%. Greatest precision was seen at the metatarsal. Further work is required to clarify the biologic significance of multisite SOS measurements and their use in the assessment of fracture risk.

Adult↗

PubMed2001

Three-point Dixon chemical-shift imaging for evaluating articular cartilage defects in the knee joint on a low-field-strength open magnet.

OBJECTIVE: The purpose of our study was to assess the value of a modified three-point Dixon MR technique for evaluating articular cartilage defects in the knee joint on a low-field-strength open magnet, correlated with arthroscopy. SUBJECTS AND METHODS: Twenty consecutive patients who underwent both MR imaging and arthroscopy of the knee joint for suspected internal derangement were examined. A modified three-point Dixon MR sequence with a single radiofrequency echo single-scan method for water and fat separation with correction of the static field inhomogeneities was performed on a 0.35-T open magnet to obtain fat suppression. The MR images were prospectively evaluated for the presence and grade of articular cartilage defects. RESULTS: Uniform fat suppression was obtained in all patients using the modified three-point Dixon technique. Fifty-nine cartilage abnormalities were identified in 19 patients on the basis of arthroscopy. Forty-seven of 59 arthroscopically proven abnormalities were prospectively detected on MR imaging. Compared with arthroscopy, the overall sensitivity of the modified three-point Dixon technique in detecting cartilage lesions was 80% and the specificity was 73%. Sixty-five percent of the cartilage abnormalities were graded identically on MR imaging and arthroscopy. CONCLUSION: The modified three-point Dixon sequence is a useful technique for achieving fat suppression in the knee joint on a 0.35-T open magnet. It is a sensitive and specific technique for the assessment of cartilage abnormalities in the knee.

Adult↗

PubMed2001

Evaluation of a gel-coupled quantitative ultrasound device for bone status assessment.

OBJECTIVE: To evaluate a new gel-coupled calcaneal quantitative ultrasound system, Osteospace (Medilink, Montpellier, France), which was designed to assess the status of bone in the calcaneus. METHODS: The study group consisted of 215 healthy white women aged 20 to 85 years and 51 white women aged 60 to 86 years with osteoporotic fractures. Fifty-two healthy women aged 50 to 85 years were randomly selected from the healthy cohort as the control group. All the women had calcaneal quantitative ultrasonic measurements. The women with osteoporotic fractures and the control group also had proximal femur and lumbar anteroposterior spine bone mineral density measurements using dual X-ray absorptiometry. Bone mineral density was also measured in a subgroup of 54 women at the calcaneus. RESULTS: There was a significant inverse correlation of broadband ultrasound attenuation and speed of sound with age (P < .001). Short-term measurement precision values expressed as coefficients of variation were 1.72% for broadband ultrasound attenuation and 0.64% for speed of sound, and standardized short-term precision values were 6.09% for broadband ultrasound attenuation and 3.87% for speed of sound. The correlations between the quantitative ultrasonic parameters and calcaneal bone mineral density were 0.69 (P = .0001) for broadband ultrasound attenuation and 0.45 (P = .0008) for speed of sound. Both quantitative ultrasonic parameters and all bone mineral density measurements of the hip and spine differed significantly between the control and osteoporotic fracture groups (P < .01). Age-, weight-, and height-adjusted odds ratios per SD decrease were as follows: broadband ultrasound attenuation, 1.79; speed of sound, 1.83; spine bone mineral density, 2.34; femoral neck bone mineral density, 1.69; and total hip bone mineral density, 1.85. The areas under the receiver operating characteristic curve for quantitative ultrasound parameters and bone mineral density measurements were close, ranging from 0.75 to 0.80. CONCLUSIONS: This new quantitative ultrasound system can detect age- and menopause-related influences on skeletal status and can discriminate healthy women from those with osteoporotic fractures in a manner comparable with that of bone mineral density measurement by dual X-ray absorptiometry.

Adult↗

PubMed2001

Radiographic damage in rheumatoid arthritis correlates with functional disability but not direct medical costs.

OBJECTIVE: Few longitudinal data exist on the relationship between radiographic damage and self-reported functional disability and direct medical costs in rheumatoid arthritis (RA). We assessed these relationships. METHODS: One hundred thirty patients with RA (at time of the first available radiograph, mean age 56.6 yrs, 16.9% male, mean disease duration 16.8 yrs) were followed for up to 13.4 years. Semiannually, they reported on functional disability (0 = no difficulty, 3 = unable to do), global severity (0 = very well, 100 = very poor), pain (0 = no pain, 3 = severe pain), and health services utilization through completion of the Stanford Health Assessment Questionnaire (HAQ). Concurrent hand radiographs were scored for erosions and joint space narrowing using the Genant method and a single score summing both erosions and joint space narrowing for both hands was calculated (0 = no damage, 200 = maximum damage). The univariate association of functional disability, global severity, pain, or direct medical costs with concurrent radiographic damage was assessed through Spearman correlations and hierarchical regression models. The hierarchical models permit exploitation of the between-patient and within-patient variation present in our longitudinal data. RESULTS: At the time of the first available radiograph, mean (SD) levels of functional disability, global severity, and pain were 1.3 (0.7), 39.4 (21.0), and 1.1 (0.7), respectively. At entry into the study, the average radiograph score was 49.7 and upon leaving the study it was 66.9. Patients were followed an average of 6.7 years, with radiograph scores increasing at an average rate of 2.5 units/yr. The Spearman correlation [95% confidence interval (CI)] between average per-patient radiograph score and average per-patient HAQ disability index, average per-patient global severity, average per-patient pain score, and average per-patient direct medical costs was, respectively, 0.42 (0.26, 0.55), 0.23 (0.06, 0.39), 0.20 (0.03, 0.36), and 0.06 (-0.11, 0.23). The mean slope (95% CI) for disability on radiograph score was 0.0186 (0.0132, 0.0226), for severity on radiographs 0.1889 (0.1295, 0.2498), and for pain on radiographs 0.0057 (0.0027, 0.0084). As an example, over 10 years, a 25 unit (i.e., 50%) increase in radiograph scores would, on average, be associated with a 0.46 unit (i.e., 35%) increase in disability, a 4.72 unit (12%) increase in global severity score, and a 0.14 unit (13%) increase in pain, all expressed on the HAQ scales. There was little association between radiograph score and direct medical costs. CONCLUSION: A clinically meaningful association exists between radiographic damage and self-reported functional disability, suggesting that interventions that slow radiographic progression may improve the patient's health status. Such a relationship was not observed between radiographic damage and direct medical costs.

Aged↗

PubMed2000

Bone loss. Quantitative imaging techniques for assessing bone mass in rheumatoid arthritis.

Osteoporosis is associated with low bone mass and microarchitectural deterioration of bone tissue with clinical manifestation of low trauma fractures. Rheumatoid arthritis (RA) is a risk factor due to generalized and articular bone loss. This minireview presents past and current bone mass measurement techniques in RA. These techniques include: plain radiographs, absorptiometry, quantitative computed tomography (QCT) and ultrasound. The most widely used technique is dual x-ray absorptiometry (DXA). RA patients have lower bone mass as compared with normals and substantial bone loss may occur early after the onset of disease. Measurement of bone mineral density (BMD) at the hand using either DXA or ultrasound maybe a useful tool in the management of RA patients.

Absorptiometry, Photon↗

PubMed2000

A multicenter, double-blind, dose-ranging, randomized, placebo-controlled study of recombinant human interleukin-1 receptor antagonist in patients with rheumatoid arthritis: radiologic progression and correlation of Genant and Larsen scores.

OBJECTIVE: To evaluate radiographic progression and the relationship of radiologic scores obtained by the Genant and Larsen methods in a clinical trial of recombinant human interleukin-1 receptor antagonist (IL-1Ra). METHODS: Patients with rheumatoid arthritis (RA) were randomized into 4 groups: placebo (n = 121) or IL-1Ra at a daily dosage of 30 mg (n = 119), 75 mg (n = 116), or 150 mg (n = 116). Hand radiographs obtained at baseline, 24 weeks, and 48 weeks were scored using both methods. RESULTS: At 24 weeks, by the Genant method, there was significant reduction in the score for progression of joint space narrowing (JSN) and the total score (a combination of erosion and JSN) in all treatment groups. Least-squares mean changes in the Genant erosion score from baseline to 24 weeks were significantly reduced after treatment with IL-1Ra at 30 mg/day and for all IL-1Ra treatment groups combined. The changes corresponded to a reduction of 38% in erosion, 58% in JSN, and 47% in total score. Patients treated with IL-1Ra at 75 mg/day had a significant reduction in the Larsen erosive joint count (LEJC), and all IL-1RA-treated groups combined showed a 45% reduction. Correlations (r) between the Genant total and Larsen scores were 0.84 at baseline, 0.83 at week 24, and 0.83 at week 48 (P < 0.0001); correlations between the Genant erosion score and the LEJC were 0.83 (P < 0.0001) at all visits; correlations between the Genant total and the Larsen scores were 0.32 and 0.49 (P < 0.0001) for progression from baseline to week 24 and from baseline to week 48, respectively; correlations between the Genant erosion score and the LEJC were 0.36 and 0.41 (P < 0.0001) for progression to weeks 24 and 48, respectively. CONCLUSION: IL-1Ra reduced radiologic progression of RA. Scores by the 2 methods correlated strongly for each individual time point, but much less strongly for assessments of disease progression.

Adult↗

PubMed2000

Comparison of digitized images with original radiography for semiquantitative assessment of osteoporotic fractures.

We validated a vertebral fracture assessment (VFA) workstation developed by our group for semiquantitative assessment of vertebral fractures in large-scale, multicenter osteoporosis drug trials. Baseline and follow-up spine radiographs (lateral views) of 50 patients who participated in a clinical trial were digitized and were archived on CD-ROM. Both original radiographs and the digitized images were independently assessed by three experienced radiologists. Prevalent fracture scores of vertebrae were rated in increments of 1 on a 4-point scale. Incident fractures were defined as any worsening of grade on follow-up films. Generally good to excellent agreement among the three readers was found between the two methods, with kappa scores (kappa) from 0.91 to 0.96 for prevalence of fractures, and from 0.80 to 0.90 for incidence of fractures. Reproducibility (intra-reader variability) of each method was comparable. For assessing prevalent fracture, kappa was from 0.87 to 0.96 using radiographs, and from 0.87 to 0.94 using VFA images. For incident fractures, the kappa was from 0.78 to 0.89 using radiographs, and from 0.82 to 0.88 using VFA images. Level-specific agreement between the two approaches was consistent. Overall, there is no difference between readings of digital images and readings of conventional radiographs. The quality of the new VFA for visualization of vertebral fracture is excellent.

Female↗

PubMed2000

Comparison of six calcaneal quantitative ultrasound devices: precision and hip fracture discrimination.

Quantitative ultrasound (QUS) is now accepted as a useful tool in the management of osteoporosis. There are a variety of QUS devices clinically available with a number of differences among them, including their coupling methods, parameter calculation algorithms and sites of measurement. This study evaluated the abilities of six calcaneal QUS devices to discriminate between normal and hip-fractured subjects compared with the established method of dual-energy X-ray absorptiometry (DXA). The short-term and mid-term precisions of these devices were also determined. Thirty-five women (mean age 74.5+/-7.9 years) who had sustained a hip fracture within the past 3 years, and 35 age-matched controls (75.8+/-5.6 years) were recruited. Ultrasound measurements were acquired using six ultrasound devices: three gel-coupled and three water-coupled devices. Bone mineral density was measured at the hip using DXA. Discrimination of fracture patients versus controls was assessed using logistic regression analysis (expressed as age- and BMI-adjusted odds ratios per standard deviation decrease with 95% confidence interval) and receiver operating characteristics (ROC) curve analysis. Measurement precision was standardized to the biological range (sCV). The sCV ranged from 3.14% to 5.5% for speed of sound (SOS) and from 2.45% to 6.01% for broadband ultrasound attenuation (BUA). The standardized medium-term precision ranged from 4.33% to 8.43% for SOS and from 2.77% to 6.91% for BUA. The pairwise Pearson correlation coefficients between different devices was highly significant (SOS, r = 0.79-0.93; BUA, r = 0.71-0.92). QUS variables correlated weakly, though significantly, with femoral BMD (SOS, r = 0.30-0.55; BUA, r = 0.35-0.61). The absolute BUA and SOS values varied among devices. The gel-coupled devices generally had a higher SOS than water-coupled devices. Bone mineral density (BMD) and BUA were weakly correlated with weight (r = 0.48-0.57 for BMD and r = 0.18-0.54 for BUA), whereas SOS was independent of weight. All the QUS devices gave similar, statistically significant hip fracture discrimination for both SOS and BUA measures. The odds ratios for SOS (2.1-2.8) and BUA (2.4-3.4) were comparable to those for femoral BMD (2.6-3.5), as were the area under the curve (SOS, 0.65-0.71; BUA, 0.62-0.71; BMD, 0.65-0.74) from ROC analysis. Within the limitation of the sample size all devices show similar diagnostic sensitivity.

Absorptiometry, Photon↗

PubMed2000

Visual assessment of vertebral deformity by X-ray absorptiometry: a highly predictive method to exclude vertebral deformity.

The accurate identification of prevalent vertebral fractures is important in both the clinical and research setting as they are associated with increased risk of further fracture and irreversible clinical consequences. This study reports a direct comparison of prevalent vertebral deformity identification using X-ray absorptiometry (XA) scans, acquired on a dual-energy X-ray absorptiometry (DXA) machine, and conventional radiographs in a diverse group of 161 postmenopausal women, ranging from healthy subjects with normal bone mineral density (BMD) to osteoporotic subjects with multiple vertebral deformities. Deformities were identified by a trained operator by visual assessment of the XA scans (VXA) and semiquantitatively by an experienced radiologist on the conventional radiographs (XSQ). Subjects were recruited prospectively and were triaged according to their VXA results into normal, equivocal and definite deformity groups. VXA and XSQ demonstrated good agreement (96.3%, K = 0.79) in classifying vertebrae as normal or deformed in the 1978 of 2093 vertebrae deemed analyzable on both the XA scans and conventional radiographs. VXA showed good sensitivity (91.9%) in the identification of moderate/severe XSQ deformities and an excellent negative predictive value (98.0%) was produced when VXA was used to distinguish subjects without vertebral deformities from those with possible or definite deformities on a per subject basis. The majority of disagreement between the two methods resulted from different classification of mild wedge and endplate deformities and the poor visualization of upper thoracic vertebrae on the XA scans. Agreement improved, particularly on a per subject basis, when analysis was restricted to the vertebral levels from L4 to T7. Visual triage of XA scans by a trained operator would seem to be swift, convenient and cost-effective method, with excellent negative predictive value, to distinguish subjects with very low risk of vertebral deformities from those with possible deformities. These 'normal' subjects can then be excluded prior to performing conventional radiographs and further time-consuming and costly methods of vertebral deformity assessment such as XSQ by an experienced radiologist and/or quantitative morphometry. VXA may prove useful in the clinical evaluation of patients at risk of osteoporosis as an adjunct to BMD scans or in the selection of subjects for osteoporosis-related clinical trials.

Absorptiometry, Photon↗

PubMed2000

Short-term increases in bone turnover markers predict parathyroid hormone-induced spinal bone mineral density gains in postmenopausal women with glucocorticoid-induced osteoporosis.

The purpose of this study was to test the ability of early changes in markers of bone turnover to predict subsequent changes in bone mineral density (BMD) induced by parathyroid hormone fragment, PTH (1-34), in postmenopausal osteoporotic women treated with estrogen and glucocorticoids. Forty-nine postmenopausal women with chronic, inflammatory diseases and BMD T-scores < or = -2.5 at the lumbar spine or femoral neck who were concurrently treated with estrogen > or = 1 year and prednisone 5-20 mg/day for > or = 1 year participated. Subjects were randomized to treatment with human PTH (1-34) 400 IU/day or to a control group for 1 year and followed for an additional year. Serum and urine were collected at baseline and 1, 3, 6, 9, 12, 18 and 24 months for measurement of bone alkaline phosphatase (BAP), osteocalcin (OC) and deoxypyridinoline (DPD). We constructed an Uncoupling Index (UI) from all three markers (UI = [ZBAP + Zoc]/2 -ZDPD, where the Z-score for each marker in each subject was calculated from the mean and standard deviation of the study population at baseline). BMD of the lumbar spine and hip was measured at baseline and every 6 months thereafter by dual-energy X-ray absorptiometry (DXA) and annually by quantitative computed tomography (QCT; spine only). BMD of the spine, but not hip (total, femoral neck or trochanter), and levels of all three markers increased significantly as a result of PTH treatment (p<0.01 compared with controls). The resorption response lagged behind that of formation as evidenced by a significant increase (p < 0.05) in the UI for the first 9 months of treatment. The UI values and changes from baseline to 1, 3 and 6 months in BAP, OC and DPD were correlated with the 12- and 24-month changes in spine BMD measured both with QCT and with DXA (Spearman's rank coefficients <0.76; p<0.05). Most PTH-treated subjects could be identified as biochemical responders by least significant change analysis. Following 1 month of therapy, BAP and OC identified 65% and 81% as responders, respectively. The responder rates were 79%, 79% and 75% for BAP, OC and DPD, respectively by 6 months. Responders exhibited a high level of diagnostic accuracy for predicting a gain in BMD (areas under the receiver operating characteristic curves exceeding 0.79 for QCT and 0.70 for DXA), but not the magnitude of the gain. These data suggest that serial bone marker measurements may be useful in identifying skeletal responders to an anabolic therapy, such as PTH, in estrogen-replete postmenopausal women with glucocorticoid-induced osteoporosis.

Aged↗

PubMed2000

Assessment of a new quantitative ultrasound calcaneus measurement: precision and discrimination of hip fractures in elderly women compared with dual X-ray absorptiometry.

The incidence of osteoporotic hip fracture increases in postmenopausal women with low hip bone mineral density (BMD). Dual X-ray absorptiometry (DXA) is the most commonly used technique for the assessment of bone status and provides good measurement precision. However, DXA affords little information about bone architecture. Quantitative ultrasound (QUS) systems have been developed to evaluate bone status for assessment of fracture risk. Our study was designed to assess a new QUS system from Hologic, the Sahara; to compare it with a previous model, the Walker-Sonix UBA 575+; and to investigate whether it is able to discriminate between women with and without fracture. Using both ultrasound devices, the measurements were performed at the heels of 33 postmenopausal women who had recently sustained hip fracture. A control group of 35 age-matched postmenopausal women was recruited for comparison. The total, neck and trochanter femoral BMD values were assessed using DXA for both groups. QUS and DXA measurements were significantly lower in fractured patients (p < 0.005) than in the control group. The short-term, mid-term and standardized short-term precisions were used to evaluate the reproducibility of the two QUS systems. The Sahara showed a better standardized coefficient of variation for broadband ultrasound attenuation (BUA) than did the UBA 575+ (p < 0.001). The correlation of BUA and speed of sound (SOS) between the two QUS devices was highly significant, with an r value of 0.92 for BUA and 0.91 for SOS. However, the correlation between DXA and ultrasound parameters ranged from 0.28 to 0.44. We found that ultrasound measurements at the heel were significant discriminators of hip fractures with odds ratios (OR) ranging from 2.7 to 3.2. Even after adjusting the logistic regressions for total, neck or trochanter femoral BMD, QUS variables were still significant independent discriminators of hip fracture. The areas under the ROC curves of each ultrasound parameter ranged from 0.75 to 0.78, and compared very well with femoral neck BMD (p > 0.05). In conclusion, our study indicated that the calcaneal QUS variables, as measured by the Sahara system can discriminate hip fracture patients equally as well as hip DXA.

Absorptiometry, Photon↗