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H K Genant

Publications and source records attributed to H K Genant.

At least 19 recordsLinked to original sources
PubMed1992

Age-related decrements in bone mineral density in women over 65.

Age-related changes in bone density contribute to the risk of fractures. To describe the relationship between age and bone mass in elderly women, we studied a large cohort of women over age 65 years who were recruited from population-based lists in four cities in the United States. Bone density in g/cm2 was measured by single-photon absorptiometry (SPA) and dual x-ray absorptiometry (DXA) at the distal and proximal radius, the calcaneus, the lumbar spine, and the proximal femur. Centralized data collection was used to control data quality and consistency. We found a strong inverse relationship between bone density and age for most sites. Decrements in bone density between women aged 65-69 years and women 85 years and older exceeded 16% in all regions except the spine, where the difference between the two age groups was 6%. Ward's triangle and the calcaneus exhibited the largest decrements, with 26 and 21%, respectively. The estimates of annual changes in bone mineral density by linear regression at sites other than the spine ranged from -0.82% at the femoral neck and trochanter to -1.30% at Ward's triangle. Correlations between the different regions ranged from r = 0.51 between the proximal radius and Ward's triangle to r = 0.66 between the distal radius and calcaneus. We conclude that the inverse relationship between age and bone mass measured by absorptiometry techniques in white women continues into the ninth decade of life. The relationship is strongest for bone density of Ward's triangle and the calcaneus and weakest for the spine.

Absorptiometry, Photon↗
PubMed1992

Axial and appendicular bone density predict fractures in older women.

To determine whether measurement of hip and spine bone mass by dual-energy x-ray absorptiometry (DEXA) predicts fractures in women and to compare the predictive value of DEXA with that of single-photon absorptiometry (SPA) of appendicular sites, we prospectively studied 8134 nonblack women age 65 years and older who had both DEXA and SPA measurements of bone mass. A total of 208 nonspine fractures, including 37 wrist fractures, occurred during the follow-up period, which averaged 0.7 years. The risk of fracture was inversely related to bone density at all measurement sites. After adjusting for age, the relative risks per decrease of 1 standard deviation in bone density for the occurrence of any fracture was 1.40 for measurement at the proximal femur (95% confidence interval 1.20-1.63) and 1.35 (1.15-1.58) for measurement at the spine. Results were similar for all regions of the proximal femur as well as SPA measurements at the calcaneus, distal radius, and proximal radius. None of these measurements was a significantly better predictor of fractures than the others. Furthermore, measurement of the distal radius was not a better predictor of wrist fracture (relative risk 1.64: 95% CI 1.13-2.37) than other sites, such as the lumbar spine (RR 1.56; CI 1.07-2.26), the femoral neck (RR 1.65; CI 1.12-2.41), or the calcaneus (RR 1.83; CI 1.26-2.64). We conclude that the inverse relationship between bone mass and risk of fracture in older women is similar for absorptiometric measurements made at the hip, spine, and appendicular sites.

Absorptiometry, Photon↗
PubMed1992

Site-matched calcaneal measurements of broad-band ultrasound attenuation and single X-ray absorptiometry: do they measure different skeletal properties?

Because of the differences in the interactions of ultrasound and x-ray waves with bone, quantitative ultrasound (QUS) techniques may yield information about skeletal status not accessible by regular bone densitometry (BD) techniques. However, relatively strong correlations have been reported between broad-band ultrasound attenuation (BUA) and several x-ray-based BD methods. We assessed the precision and association of single x-ray absorptiometry (SXA) and BUA of the calcaneus. We examined both BUA and SXA at the calcaneus using special software for matching the regions of interest. An algorithm was derived and applied to correct the observed correlation coefficients for the attenuation effect caused by the precision errors for BUA and SXA. In a group of 33 volunteers covering a wide range of age and calcaneal bone mineral densities, the site-matched and precision-adjusted correlation coefficient between BUA and SXA was r = 0.58, with a standard error of the estimate (SEE) of 14.41 dB/MHz, or 17.08%. For the subgroup of 25 women the correlation was stronger, with r = 0.72 and SEE = 11.53 dB/MHz, or 14.33%. SXA precision was 0.79% for the regular region of interest (ROI) and 1.22% for the site-matched ROI. BUA precision was 2.76% for the entire subject group and 1.63% for women of age 40 or older. The observed correlation coefficient between ultrasound and x-ray based techniques of the order of 0.7 is significant, but it leaves about 50% of the variability unexplained.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

MRI of the shoulder.

MR imaging of the shoulder has become an important imaging modality for that joint. Excellent soft tissue contrast and multiplanar acquisition provide optimal assessment of muscle, tendons, hyaline and fibrous cartilage, joint capsules, fat, bursae and bone marrow. The most common indications for shoulder MRI are suspected rotator cuff tear, shoulder instability, osteonecrosis, neoplasm and infection. In this article we describe MR technique, special anatomy of the shoulder, and diagnostic MR criteria of common pathologic conditions.

Humans↗
PubMed1992

The lumbar spine: postoperative magnetic resonance imaging.

Persistent low back pain after surgery can be a severe diagnostic and therapeutic problem. By using MRI many causes of this failed back surgery syndrome (FBSS) can be disclosed. MRI is superior to other imaging modalities in this concern. In this article we describe the MR technique, normal and abnormal findings of the postoperative lumbar spine, such as persistent or recurrent disc herniation, epidural scar, spinal stenosis, pseudomeningocele, arachnoiditis, pseudarthrosis, hematoma, and infection.

Humans↗
PubMed1979

Computed tomography evaluation of fatty tumors of the somatic soft tissues: clinical utility and radiologic-pathologic correlation.

The role of computed tomography (CT) in the evaluation of fatty tumors of the somatic soft tissues was investigated. Six surgically proven cases of fatty tumors were studied preoperatively by CT and standard radiographic means--conventional radiographs, xeroradiography, and angiography. Our case material included a simple lipoma, two infiltrative lipomas, an angiolipoma, and two liposarcomas. The radiologic-pathologic correlation was evaluated with respect to the various imaging modalities. The unique tissue characteristics of fatty tumors makes them particularly adaptable to CT scanning. In addition to its ability to define accurately tissue densities, the facility of CT in depicting depth, size, and extent of the lesion in the axial plane was found to be most useful in the preoperative evaluation of our case material.

Adipose Tissue↗
PubMed1979

Controlled single-blind clinical evaluation of low-dose mammographic screen--film systems.

The ability of five low-dose mammographic screen--film systems to portray normal and abnormal breast structures was evaluated in parallel with a study of physical image properties. Single-blind evaluations of the visibility of normal breast architecture, mass lesions, and calcifications were made on the mammograms of 100 patients radiographed with each of the systems. There was increased noise and slightly poorer resolution for the faster recording systems, but there was no difference in final diagnostic impressions among the five systems. These results suggest that the faster systems will result in substantial dose reduction without sacrificing diagnostic accuracy.

Breast Diseases↗
PubMed1979

99mTc-methylene diphosphonate bone imaging in the evaluation of total hip prostheses.

A retrospective study was performed to determine the accuracy of 99mTc-methylene diphosphonate bone imaging in the evaluation of total hip arthrosplasty for lossening and/or infection. Using focally increased activity at the tip of the femoral component or in the region of the acetabular component as a criterion, the examination was 77% specific and 100% sensitive for loosening and/or infection. A possible explanation for the increased uptake at the tip of the femoral component and the role of this examination in the management of a painful total hip prosthesis are discussed.

Bone Diseases↗
PubMed1978

Avascular necrosis of bone after renal transplantation.

Avascular necrosis (AN) of bone developed in 11 of 100 children who received renal transplants from 1964 to 1977. Bones involved were femoral heads, 14; femoral condyles, 12; tall, two; and carpal naviculars, two. Seven children with symptomatic AN of the femoral heads were treated with limited weight bearing; three subsequently required arthroplasty, and degenerative joint disease developed in one. The AN at other joints healed clinically but not roentgenographically. Although the prevalence of AN decreased after 1967 coincident with a decrease in prednisone dose, children with AN received the same cumulative prednisone dose as children in a control group. Serum phosphorus levels were different in the AN and control groups, but other indexes of hyperparathyroidism were similar. The relative contributions of prednisone therapy and hyperparathyroidism to the development of AN could not be delineated.

Adolescent↗
PubMed1978

Ratio of late to early radionuclide uptake: a method for distinguishing osteoporosis from osteomalacia in animal models.

The ration of late to early uptake of several radionuclides was examined as a method for distinguishing states of abnormal bone metabolism. Nutritional osteoporosis (secondary hyperparathyroidism) and osteomalacia were produced in young rats and compared to a control group. The ratio of early (3-6 hrs.) to late (4-6 days) uptake of barium-131, nitrate, indium-111 EDTMP, and lead-203 were studied, as was that of strontium-85 chloride, a calcium analogue. Ratios of late to early uptake were found to distinguish osteomalacia from osteoporosis in the models when strontium-85 or barium-131 were used. Barium-131 may be a clinically useful alternative to strontium-85 in the evaluation of metabolic bone disease due to its shorter half-life and lower radiation dose.

Animals↗
PubMed1978

HLA-B27 associated arthropathies.

The association between histo-compatibility antigens and disease is reviewed, in particular that between HLA-B27 and spondylitic disorders, i.e., ankylosing spondylitis, Reiter's arthritis, psoriatic arthritis, and ankylosing hyperostosis. We determined whether the presence of HLA-B27 predicted specific radiographic findings and, conversely, whether specific radiographic changes predicted antigenic status. The prevalences of the HLA-B27 antigen in our patients were: ankylosing spondylitis, 100%; Reiter's arthritis, 93%; psoriatic arthritis, 55%; and ankylosing hyperostosis, 12%. The only specific radiographic finding associated with B27 positivity was severe spondylitis in psoriasis.

Arthritis↗