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H K Genant

Publications and source records attributed to H K Genant.

At least 199 records · Page 11Linked to original sources
PubMed1996

Dual X-ray absorptiometry quality control: comparison of visual examination and process-control charts.

Dual X-ray absorptiometry (DXA) is widely used to monitor treatment efficacy in reducing the rate of bone mineral loss. In order to assure the validity of these measurements, instrument quality control of the DXA scanners becomes very important. This paper compares five quality control procedures (visual inspection, Shewhart chart with sensitizing rules, Shewhart chart with sensitizing rules and a filter for clinically insignificant mean changes, moving average chart and standard deviation, and cumulative sum chart [CUSUM]) in their ability to identify scanner malfunction by means of (1) an analysis of five longitudinal phantom data sets that had been collected during a clinical trial and (2) an analysis of simulated data sets. The visual inspection method is relatively subjective and depends on the operator's experience and attention. The regular Shewhart chart with sensitizing rules has a high false alarm rate. The Shewhart chart with sensitizing rules and an additional filter for clinically insignificant mean changes has the lowest false alarm rate but a relatively low sensitivity. The CUSUM method has good sensitivity and a low false alarm rate. In addition, this method provides an estimate of the date a change in the DXA scanner performance might have occurred. The method combining a moving average chart and a moving standard deviation chart came closest to the performance of the CUSUM method. Comparing the advantages and disadvantages of all methods, we propose the use of the CUSUM method as a quality control procedure for monitoring DXA scanner performance. For clinical trials use of the more intuitive Shewhart charts may be acceptable at the individual sites provided their scanner performance is followed up by CUSUM analysis at a central quality assurance center.

Absorptiometry, Photon↗
PubMed1996

Comparison of semiquantitative visual and quantitative morphometric assessment of prevalent and incident vertebral fractures in osteoporosis The Study of Osteoporotic Fractures Research Group.

The assessment of radiographs for vertebral fractures is important in the clinical evaluation of patients with suspected osteoporosis, in the epidemiological evaluation of elderly populations, and in clinical trials of osteotrophic drugs. The purpose of this study is to compare visual semiquantitative (SQ) approaches and quantitative morphometric approaches for assessing prevalent and incident vertebral fractures in postmenopausal osteoporosis. We analyzed lateral thoracolumbar spine radiographs (baseline and approximately 3.5 year follow-up) of 503 women (age > or = 65) randomly selected from the Study of Osteoporotic Fractures (SOF) population. SQ assessment by an experienced radiologist graded vertebral fractures from 0 (normal) to 3 (severe). Incident fractures by SQ were defined as an increase of > or = 1 grade on follow-up radiographs. Trained research assistants visually triaged women as normal, uncertain, or probably fractured and visually flagged vertebrae with moderate/severe (grade > or = 2) prevalent fractures or with any (grade > or = 1 change) incident fracture. The radiographs were also digitized by research assistants, and quantitative morphometry (QM) was used to classify vertebral deformities at several cut-offs based on standard deviation (SD) reductions in height ratios from normal means, e.g., QM > or = 3 SD. Incident fractures by QM were defined as a decrease in height of more than 15% (QM15) on follow-up radiographs. Finally, a combination of these methods was used to detect moderate/severe prevalent fractures and any grade of incident fractures. In the overall analysis, the prevalence of fractures varied from 14 to 33% and the incidence from 5 to 10% by woman, depending upon the method and cut-off criteria. In the detailed analysis, considering visually triaged uncertain as abnormal, triage by research assistants detected 97.0% (163/168) of women with SQ grade > or = 1 fractures and 100% (70/70) with SQ grade > or = 2 fractures. Visual flagging by research assistants detected 88.5% (108/122) of SQ > or = 2 prevalent fractures (kappa score, kappa = 0.82) and 85.2% (52/61) of SQ incident fractures (kappa = 0.79). QM > or = 3 SD detected 37.9% (141/372) of SQ > or = 1 prevalent fractures (kappa = 0.51) and 79.5% (97/122) of SQ > or = 2 prevalent fractures (kappa = 0.68), plus 18 vertebrae without SQ fractures. QM 15 detected 59% (36/61) of SQ incident fractures (kappa = 0.70), plus five vertebrae without SQ incident fractures. The combination assessment detected 92% (112/122) of SQ > or = 2 prevalent fractures (kappa = 0.76) and 84% (51/61) of SQ incident fractures (kappa = 0.91). The precision errors of QM vertebral height measurements (baseline versus follow-up) ranged from 2.71 to 2.92%. Nevertheless, excluding the 5719 vertebrae that were clearly normal by morphometry, i.e., within 2 SD of the normal means at both baseline and follow-up, two-thirds (358/556) of the remaining vertebrae changed classification by at least 1 SD category. Visual triage and visual flagging by research assistants appear to be highly effective methods for vertebral fracture assessment in osteoporosis, potentially reducing the number of false-positive and false-negative fractures detected by QM, at least relative to SQ by the radiologists. There is higher concordance among the visual approaches studied than between the visual SQ and quantitative morphometric approaches, with QM having limited ability to detect mild fractures but good ability to detect moderate/severe fractures, as classified by SQ. Use of a combination of sensitive qualitative and quantitative criteria, with adjudication by an experienced radiologist, is feasible and draws upon the relative strengths of each of the methods. Quantitative morphometry should not be performed in isolation, particularly when applying highly sensitive morphometric criteria at low threshold levels, without visual assessment to confirm the detected prevalent or incident vertebral defor

Aged↗
PubMed1996

Decay characteristics of bone marrow in the presence of a trabecular bone network: in vitro and in vivo studies showing a departure from monoexponential behavior.

In this study, we examine MRI T2' decay characteristics for bone marrow in trabecular bone networks, using an asymmetric spin-echo sequence to isolate the inhomogeneous decay due to susceptibility variations between bone and marrow or water. In in vitro measurements on trabecular bone specimens from human vertebral bodies, tibia, and radii, we find significant deviations from a monoexponential signal decay. The initial decay is seen to have a Gaussian decay character, switching to a primarily exponential decay at later decay times. A similar trend is observed in in vivo measurements in the distal radius. Unlike an exponential decay, which may be characterized by a single decay rate, this is indicative of a significant variation in the decay rate with time. The deviations from exponential decay are seen to be orientation dependent, being most significant when the primary trabecular orientation is perpendicular to the static magnetic field.

Bone Marrow↗
PubMed1996

Accuracy and precision study in vitro for peripheral quantitative computed tomography.

We evaluated the accuracy and precision of a peripheral quantitative computed tomography (pQCT) scanner, the Stratec XCT-960, using 12 human cadaveric forearms. The accuracy was determined by comparing the total bone mineral content (BMC) with the ash weight (AW). We scanned and ashed three consecutive slices (thickness 2.5 mm) at the standard position (s-position) and at 2.5 mm both proximal and distal to the s-position. The correlation coefficient between the AW and total BMC using slices at the s-position was r = 0.87 with an accuracy error (random component) of 15.5%. The correlation coefficient using all slices was r = 0.90 with an accuracy error of 14.3%. The correlation coefficient improved to r = 0.95 with an accuracy error of 9.7% after averaging the results of all three slices for each forearm. The short-term precision error expressed as the coefficient of variation (CV) of bone mineral density (BMD) and BMC was determined by measuring the forearms five times either with repositioning or without repositioning. The CVs with repositioning were 2.77 and 1.15 for total BMD and BMC, 1.85 for trabecular BMD; without repositioning they were 0.29, 0.58 and 0.69 respectively. To further evaluate the influence of positioning, additional scans were performed at 1, 2 and 5 mm proximal, and 1 and 2 mm distal to the s-position. BMD and BMC were greatly influenced by the scan location; for example, the percentage differences in trabecular BMD 1 mm distal and proximal relative to the s-position were 2.5% +/- 5.1% and 0.18% +/- 6.3%, respectively. The Stratec XCT-960 appears to be a moderately accurate and highly precise scanner with potential usefulness for evaluating BMC and BMD of ultradistal radius.

Bone Density↗
PubMed1996

Advances in the noninvasive assessment of bone density, quality, and structure.

Recent advances in the development of methods to assess the skeleton noninvasively have contributed to screening for risk of osteoporosis, early detection of the disease, and effective monitoring of its progression and response to therapy. The capability now exists to evaluate the peripheral, central, or entire skeleton as well as the trabecular bone or cortical bone envelopes accurately and precisely, with the capacity to determine bone strength and predict fracture risk. In this article we examine the current and future capabilities of quantitative computed tomography (QCT), quantitative ultrasound (QUS), and magnetic resonance microscopy (muMR) to assess architectural and densitometric properties of the skeleton to enhance the prediction of fracture risk.

Female↗
PubMed1996

Magnetic resonance imaging of labral cysts of the hip.

OBJECTIVE: To present the magnetic resonance (MR) imaging findings in patients with labral cysts adjacent to the acetabulum and to examine their association with hip pathology. DESIGN: MR images and conventional radiographs of seven patients with paralabral cysts were retrospectively reviewed by three musculoskeletal radiologists. PATIENTS: The patients included three men and four women with hip pain, ranging in age from 29 to 82 years. Two patients had developmental dysplasia of the hip and six had a history of remote trauma/dislocation. Clinical history and follow-up were obtained in all patients. Surgery was performed on one patient. RESULTS AND CONCLUSIONS: Paralabral cysts were located in the posterosuperior aspect of the hip joint in five patients and in the anterior aspect in two patients. A tear of the adjacent acetabular labrum was confirmed surgically in one patient, and in all patients the MR features suggested the presence of an abnormal labrum. Osteoarthritis was observed in three patients and there was associated subchondral cyst formation in the acetabulum adjacent to the cyst in three patients. The paralabral cyst of the hip is well visualized on MR imaging and is seen in patients with a predisposition to labral pathology.

Acetabulum↗
PubMed1996

Clinical utility of bone mass measurements in adults: consensus of an international panel. The Society for Clinical Densitometry.

Low bone mass predicts future fracture risk as well as high cholesterol or high blood pressure can predict the risk of heart disease or stroke. Prevention of the first fracture should be a clinical goal. In patients without fractures, osteopenia and osteoporosis can be diagnosed based on the extent of reduction in bone mass below mean peak bone mass of young healthy individuals. As bone mass decreases, fracture risk increases exponentially. Clinical situations in which an assessment of bone mass and fracture risk affects therapeutic decisions include estrogen deficiency, vertebral abnormalities, radiographic osteopenia, asymptomatic primary hyperparathyroidism, and long-term corticosteroid therapy. Serial measurements can also be used to monitor the effects of osteoporosis treatments. The appropriate technique and skeletal site for bone mass measurements should be chosen based on the patient's circumstances and the precision of measurement. A clinical interpretation can enhance the value of computer-generated bone mass measurement reports and improve decision making.

Absorptiometry, Photon↗
PubMed1996

Magnetic resonance imaging of the calcaneus: preliminary assessment of trabecular bone-dependent regional variations in marrow relaxation time compared with dual X-ray absorptiometry.

RATIONALE AND OBJECTIVES: Marrow transverse relaxation time (T2*) in magnetic resonance (MR) imaging may be related to the density and structure of the surrounding trabecular network. We investigated regional variations of T2* in the human calcaneus and compared the findings with bone mineral density (BMD), as measured by dual X-ray absorpiometry (DXA). Short- and long-term precisions were evaluated first to determine whether MR imaging would be useful for the clinical assessment of disease status and progression in osteoporosis. METHODS: Gradient-recalled echo MR images of the calcaneus were acquired at 1.5 T from six volunteers. Measurements of T2* were compared with BMD and (for one volunteer) conventional radiography. RESULTS: T2* values showed significant regional variation; they typically were shortest in the superior region of the calcaneus. There was a linear correlation between MR and DXA measurements (r = .66 for 1/T2* versus BMD). Differences in T2* attributable to variations in analysis region-of-interest placement were not significant for five of the six volunteers. Sagittal MR images had short- and long-term precision errors of 4.2% and 3.3%, respectively. For DXA, the precision was 1.3% (coefficient of variation). CONCLUSION: MR imaging may be useful for trabecular bone assessment in the calcaneus. However, given the large regional variations in bone density and structure, the choice of an ROI is likely to play a major role in the accuracy, precision, and overall clinical efficacy of T2* measurements.

Absorptiometry, Photon↗
PubMed1996

Distal radius: in vivo assessment with quantitative MR imaging, peripheral quantitative CT, and dual X-ray absorptiometry.

PURPOSE: To evaluate in vivo the relationship between magnetic resonance (MR) imaging relaxation time and bone mineral density (BMD) at the distal radius. MATERIALS AND METHODS: The 1/T2* MR imaging relaxation rates and dual X-ray absorptiometry (DXA) measurements were evaluated in the trabecular bone of the distal 5 cm of the radius in 14 healthy premenopausal women and 11 healthy postmenopausal women and in 11 women with osteoporosis. Trabecular and total BMD were measured with peripheral quantitative computed tomography (CT). RESULTS: In healthy women, 1/T2* values and trabecular BMD at peripheral quantitative CT were significantly correlated but 1/T2* and total BMD were not. Statistically significant (P = .03) correlations between 1/T2* and DXA were found only in the most distal area covered with DXA. The 1/T2* values were more closely correlated with age and showed higher relative annual decreases (0.47%-0.81%) than peripheral quantitative CT (0.20%-0.59%) or DXA (0.10%-0.39%). Pre- and postmenopausal healthy subjects could be distinguished only with MR imaging, and postmenopausal healthy and osteoporotic subjects only with CT and DXA. CONCLUSION: MR imaging relaxation rates correlate well with trabecular BMD in vivo.

Absorptiometry, Photon↗
PubMed1996

Osteoporosis: association of recent fractures with quantitative US findings.

PURPOSE: To study the association of quantitative ultrasound (US) parameters and bone mineral density (BMD) in patients with and patients without recent fractures. MATERIALS AND METHODS: The authors studied 4,698 women (69 years or older) who had sustained 1,363 new fractures, including 106 hip fractures, during the 7 years prior to the study. Broadband ultrasound attenuation (BUA) and other velocity parameters were measured by means of quantitative US of the calcaneus. BMD was measured at the spine, hip, and calcaneus. RESULTS: The standardized age-adjusted odds ratio for all fractures was 1.5 (95% confidence interval [CI] = 1.4, 1.7) for BUA and up to 1.6 (95% CI = 1.5, 1.7) for BMD. For hip fractures, the odds ratio was 1.9 (95% CI = 1.5, 2.4) for BUA and up to 2.6 (95% CI = 2.0,3.4) for BMD. Sensitivity and specificity with BUA, velocity parameters, and BMD were comparable. Results of multivariate analysis showed that both BUA and BMD were independently associated with fractures and that combined measurements improved sensitivity and specificity. CONCLUSION: Quantitative US parameters are strongly associated with risk of fracture and partly independent of BMD. This simple, low-cost, portable, and radiation-free approach may complement bone densitometry in assessing risk of osteoporotic fracture.

Aged↗
PubMed1996

Indirect MR arthrography: optimization and clinical applications.

PURPOSE: To evaluate and optimize a method for producing magnetic resonance (MR) images similar to MR arthrograms of multiple synovial joints with intravenous gadopentetate dimeglumine injection. MATERIALS AND METHODS: The authors examined the effects of joint motion, dose of gadopentetate dimeglumine (0.1, 0.2, and 0.4 mmol/kg), and fat saturation on the enhancement rate of the joint cavity and the degree of image contrast generated among articular structures on MR images in 14 healthy volunteers. Shoulder, elbow, wrist, hip, knee, and ankle joints of 10 volunteers were imaged with optimized parameters. Indirect MR arthrographic findings in 17 patients with joint disorders (eg, rotator-cuff tears, meniscal tears, and osteoarthritis) were compared with arthroscopic findings. RESULTS: Fat-saturated images obtained after 10 minutes of exercise and administration of 0.1 mmol/kg gadopentetate dimeglumine were similar to those obtained after intraarticular injection of contrast medium. Exercising the joint yielded the strongest joint-cavity enhancement. Increasing the dose of contrast medium in the unexercised joint did not statistically significantly improve the contrast-to-noise ratio. Rotator cuff tears, meniscal tears, and cartilage defects were better delineated with this method than with unenhanced MR imaging and showed good correlation with arthroscopic results. CONCLUSION: Indirect MR arthrography of an exercised joint provides homogeneous enhancement and improved delineation of soft-tissue structures.

Adult↗
PubMed1996

Quantitative CT assessment of the lumbar spine and radius in patients with osteoporosis.

OBJECTIVE: We undertook this study to quantify the relationship between bone mineral assessments of the lumbar spine using quantitative CT (QCT) and of the radius using peripheral QCT (pQCT) and to test the sensitivity of both techniques in detecting changes in bone mass that are related to age and osteoporosis. SUBJECTS AND METHODS: Forty-two healthy premenopausal, 38 healthy postmenopausal, and 97 osteoporotic postmenopausal women were examined with pQCT of the distal radius and with QCT of the lumbar spine (L1-L4). The bone mineral density (BMD), bone mineral content (BMC), and a cross-sectional area of cortical bone were assessed at the distal radius. The BMD of trabecular and total bone and the BMC of total bone were assessed at the midvertebral bodies of the lumbar spine. RESULTS: In the healthy women, correlations of radial BMD with spinal trabecular and total BMD were modest (r = .39 and r = .49, respectively) but were higher for total BMC (r = .79). All correlations in osteoporotic women (r = .19 for trabecular BMD, r = .31 for total BMD, and r = .47 for total BMC) were lower than those in healthy women. For measurement of spinal bone mass in healthy women, trabecular BMD showed a higher correlation with age (r = .81) and a larger relative annual decrease (1.2%) than did total BMD (r = .75, .78%) or total BMC (r = .54, .55%). At the radius, the highest correlations with age were found for total BMC (r = .57, .53%), cortical area (r - .52, .67%), and cortical BMC (r = .48, .78%). Age-adjusted odds ratios for prevalent vertebral fractures were highest for total (4.5) and trabecular (4.4) spinal BMD. For radial measurements, odds ratios were highest for both total BMD (2.3) and cortical area (2.3). CONCLUSION: QCT of spinal trabecular bone showed the strongest capability for assessment of age-related bone loss and for discrimination of osteoporotic vertebral fractures. In comparison, pQCT of radial trabecular bone showed the weakest capability for these applications, and pQCT of radial cortical or total bone showed intermediate capability.

Aged↗
PubMed1996

Emerging applications of magnetic resonance imaging in the evaluation of articular cartilage.

MR imaging rapidly is emerging as a tool of unparalleled power for examining the articular cartilage and other important structures in diarthrodial joints. In addition to delineating the morphology of cartilage, MR imaging is capable of quantifying a variety of compositional and functional parameters relevant to arthritis. Moreover, because MR imaging is a nondestructive technique, multiple parameters can be analyzed in the same region of tissue and frequent serial examinations can be performed on even asymptomatic patients. This offers an unprecedented opportunity to study arthritis in ways not imaginable before and potentially to expand the envelope of MR imaging to include a population of patients for whom imaging has had relatively little to offer.

Cartilage Diseases↗
PubMed1996

Ganglia and cysts around joints.

Para-articular cysts frequently are seen on routine imaging examinations. They may be clinically asymptomatic or may cause pain, swelling, or impaired joint function. They often are associated with underlying joint disorders, such as trauma, degeneration, or inflammation. This article discusses the cause, symptoms, and appearance of para-articular cysts on various imaging examinations including arthrography, ultrasound, CT scan, and MR imaging. Specific attention is focused on those cystic masses appearing around the hip, knee, ankle and foot, shoulder, elbow, wrist and hand, spine, temporomandibular joints, and periosteum.

Arthrography↗
PubMed1996

Five years of clinical experience with intermittent cyclical etidronate for postmenopausal osteoporosis.

OBJECTIVE: To evaluate the effects of 120 weeks of intermittent cyclical etidronate on the progression of bone loss and fracture incidence and rate in postmenopausal osteoporotic women after 150 weeks of either etidronate or placebo treatment. METHODS: This was an open label followup study of 37 postmenopausal osteoporotic women enrolled from the earlier 150 week study, 17 from the etidronate group and 20 from the placebo group. Treatment cycles were of oral doses of etidronate 400 mg/day for 2 weeks, followed by a 13 week drug-free period for a total of 120 weeks. All patients received a daily supplement of 0.5 g calcium and 400 U vitamin D. RESULTS: During the earlier 150 week study, mean vertebral bone mineral content increased significantly in the etidronate group by 5.5% (p = 0.013) and decreased by 2.7% (not significant) in the placebo group. After 120 weeks of etidronate treatment in this followup study, patients who had formerly received etidronate experienced an additional 1.4% increase; after 5 years, bone mineral content was 6.9% above the original baseline (p = 0.037). Bone mineral content also increased in the former placebo group during the latter study, up to 5.3% above the original study baseline (not significant). The vertebral fracture rate in the former placebo group decreased significantly, from 103 to 27 per 100 patient-years (p < 0.01), while the fracture rate in the former etidronate group was unchanged (38 and 33 per 100 patient-years). CONCLUSION: Five years of etidronate therapy for postmenopausal osteoporosis results in significant increases in vertebral bone mineral content, and the previously observed reduction in vertebral fracture rate in the etidronate group is maintained during at least 5 years of therapy.

Aged↗
PubMed1996

Assessment of joint space width in patients with osteoarthritis of the knee: a comparison of 4 measuring instruments.

OBJECTIVE: To evaluate the intra and interobserver reproducibility of 4 measuring instruments for assessing joint space width in knee osteoarthritis (OA) and to estimate the effects of patients, instrument, session order, and reader variation. METHODS: We studied 30 patients with unilateral tibiofemoral OA selected to represent a broad range of radiographic changes. Joint space width (JSW) was measured on plain anteroposterior weight bearing radiographs. Using an experimental design, 3 readers assessed JSW 3 times with 4 measuring instruments (ruler, caliper, graduated magnifying glass, digitized assessment). RESULTS: Intra and interobserver reproducibility was high with all measuring instruments (intraclass correlation coefficients from 0.95 to 0.98 and from 0.91 to 0.97, respectively). Analysis of variance (ANOVA) showed a patient effect (p < 10(-6)), a reader effect (p = 0.0001), an instrument effect (p = 0.0001), and a session order effect (p = 0.04). The variance component estimates were patients 55%, readers 34%, session order 2%, instruments 8%. ANOVA performed separately for each instrument showed that session order differences always represented less than 1% of the total variance. The reader component accounted for 0% of the total variance for the ruler, 2% for the digitized method, 16% for the caliper, and 18% for the graduated magnifying glass. CONCLUSION: Ruler and digitized assessment have better reliability than caliper and graduated magnifying glass.

Analysis of Variance↗