Assessing osteoporosis: CT's quantitative advantage.
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Absorptiometry, Photon↗
Biomedical subjects
H K Genant
Publications and source records attributed to H K Genant.
CT in low back pain syndrome.
CT has become the imaging modality of choice for diagnosing the specific cause of low back pain syndrome. This article describes and illustrates those abnormalities commonly associated with low back pain: disk herniation, spinal stenoses, facet joint abnormalities, spondylosis, inflammatory conditions of the lumbar spine, and sacroiliitis.
Adolescent↗
Computed tomography of the hip.
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Bone Neoplasms↗
Magnetic resonance imaging of the hip.
Magnetic resonance imaging of the musculoskeletal system in general and the hip in particular offers many exciting opportunities for innovative and revolutionary diagnostic avenues, the full potential of which awaits further investigative and clinical experience.
Bone Marrow Diseases↗
Osteoporosis: assessment by quantitative computed tomography.
The results presented in this article indicate that quantitative computed tomography provides a reliable means of evaluating and monitoring the many forms of osteoporosis and its various treatments. The greatest advantages of spinal QCT for noninvasive bone mineral measurement are its high precision, the high sensitivity of the vertebral spongiosa measurement site, and the potential for widespread application.
Adult↗
The aging skeleton.
The importance of bone loss with aging increases year by year. When Bismarck set the age of retirement at 65, it did not cost Prussia much because few lived to receive pensions. At the turn of the century, only 4.1 per cent of our population was 65 or older. But the present change in demography, called "The Graying of America," means that we now have 13 per cent of the population 65 or older: 35 million people, 20 million women and 15 million men. For the women who are now passing through menopause or who have had oophorectomies, the predictable deformities caused by fractures of the vertebrae, wrists, and hips will make up the single largest cause of hospitalization unless prophylaxis against postmenopausal bone loss is instituted. The best established prophylaxis is now low-dose estrogen-gestagen replacement therapy. Very promising is the combination of very-low-dose estrogen and high-dose oral calcium supplements (Fig. 17). For women who cannot or will not take estrogens, certain progestational agents offer equal protection to bone, though, of course, these agents do not protect against atrophy of the other target organs, most notably the vaginal mucosa.
Adult↗
Assessment of metabolic bone diseases by quantitative computed tomography.
Advances in the radiologic sciences have permitted the development of numerous noninvasive techniques for measuring the mineral content of bone, with varying degrees of precision, accuracy, and sensitivity. The techniques of standard radiography, radiogrammetry, photodensitometry, Compton scattering, neutron activation analysis, single and dual photon absorptiometry, and quantitative computed tomography (QCT) are described and reviewed in depth. Results from previous cross-sectional and longitudinal QCT investigations are given. They then describe a current investigation in which they studied 269 subjects, including 173 normal women, 34 patients with hyperparathyroidism, 24 patients with steroid-induced osteoporosis, and 38 men with idiopathic osteoporosis. Spinal quantitative computed tomography, radiogrammetry, and single photon absorptiometry were performed, and a spinal fracture index was calculated on all patients. The authors found a disproportionate loss of spinal trabecular mineral compared to appendicular mineral in the men with idiopathic osteoporosis and the patients with steroid-induced osteoporosis. They observed roughly equivalent mineral loss in both the appendicular and axial regions in the hyperparathyroid patients. The appendicular cortical measurements correlated moderately well with each other but less well with spinal trabecular QCT. The spinal fracture index correlated well with QCT and less well with the appendicular measurements. Knowledge of appendicular cortical mineral status is important in its own right but is not a valid predictor of axial trabecular mineral status, which may be disproportionately decreased in certain diseases. Quantitative CT provides a reliable means of assessing the latter region of the skeleton, correlates well with the spinal fracture index (a semiquantitative measurement of end-organ failure), and offers the clinician a sensitive means of following the effects of therapy.
Aged↗
Characteristic CT manifestations of uncommon spinal disorders.
This article identifies many disorders seen on CT scans of the spine that should be recognized to avoid submitting the patient to additional diagnostic tests or even surgery. These disorders are not easily categorized, however, and could best be described as normal variants and pitfalls in CT diagnosis of the spine.
Humans↗
Magnetic resonance imaging of the musculoskeletal system.
MRI is a complementary technique to CT in the examination of the spine, the hip, and musculoskeletal tumors. In some cases, it provides diagnostic information not available with any other modality, including CT. MRI has the potential to be very useful in the assessment of various marrow-based disorders and may someday obviate the need for contrast-aided studies of ligaments, tendons, and cartilage.
Aged↗
Magnetic resonance imaging in osteonecrosis of the femoral head.
Magnetic resonance imaging (MRI) has been used in the assessment of patients with osteonecrosis of the femoral head. Preliminary results indicate that the technique is sensitive to early changes that occur within marrow elements as well as to later changes that involve trabecular bone. Advantages of MRI include its noninvasiveness, the lack of ionizing radiation, a high sensitivity to pathologic changes in bone, and the capability of producing images of equal resolution in all planes.
Adult↗
Subsidence of the femoral prosthesis. A stereophotogrammetric evaluation.
A quantitative three-dimensional measurement method, radiographic stereophotogrammetry (SPG), was employed to assess the relation between early subsidence of the femoral prosthesis after total hip arthroplasty (THA) and subsequent clinical course. The SPG technique and the authors' error control mechanisms are described in 15 patients in the early postoperative period, and the findings are correlated with those of follow-up clinical examinations. Among the 12 patients who remained clinically asymptomatic with respect to pain, only one had an SPG estimate of subsidence in excess of 1 mm at any point in time. Each of the three patients who later became symptomatic had SPG estimates of subsidence in excess of 1.75 mm within six months of the operation. Thus far, the patient with the largest estimate of subsidence is the only one who required surgical revision.
Evaluation Studies as Topic↗
Decreased spinal mineral content in amenorrheic women.
Premenopausal amenorrheic women may be at risk for the development of osteoporosis. In hyperprolactinemia, cortical bone mass is decreased and the magnitude of the decrease correlates with the severity of the estrogen deficiency. However, bone loss in women with amenorrhea from other causes has not been assessed. We have studied women with hypothalamic and hyperprolactinemic amenorrhea and premature ovarian failure. Bone mass in the peripheral cortical bone was only slightly decreased from age-matched controls, but spinal trabecular bone was decreased 20% to 30%. Estradiol levels were 20 to 80 pg/mL in these women, not different from normal early follicular levels. The decrease in bone mass in the spine did not correlate with serum estradiol at these levels. The hypothalamic amenorrhea group was made up of athletes in whom the bone mass decrease was an unexpected finding.
Adolescent↗
Primary cystic arthrosis of the hip.
Subchondral cysts can mimic the radiographic features of intra-osseous ganglia or a variety of neoplastic processes. This case demonstrates the development of a massive subarticular cyst in the supra-acetabular bone. The unique pathogenesis of subchondral cysts is illustrated by the evolution of radiographic features that may be useful in planning treatment.
Bone Cysts↗
The normal sacroiliac joint: a CT study of asymptomatic patients.
The sacroiliac (SI) joints of 45 asymptomatic subjects were prospectively studied to define better the normal appearance of SI joints on CT scans and thereby attach appropriate significance to CT signs of sacroiliitis. We evaluated joint space narrowing, subchondral sclerosis, erosions, ankylosis, osteophytes, subchondral cysts, and symmetry. The results indicate that the SI joints demonstrate symmetry in patients under the age of 30 (100% of subjects in this age group). Asymmetry was demonstrated in 77% of subjects over the age of 30 and in 87% of subjects over the age of 40. Abnormal CT findings of sacroiliitis, which occurred frequently in the asymptomatic population and thus by themselves are believed to be poor indicators of sacroiliitis, include nonuniform iliac sclerosis (83%), focal joint space narrowing in patients over the age of 30 (74%), and ill-defined areas of subchondral sclerosis, particularly on the iliac side (67%). Those CT findings of sacroiliitis that occurred infrequently in the asymptomatic population, and hence may represent good indicators of sacroiliac disease, include increased sacral subchondral sclerosis in subjects under the age of 40 (11%), bilateral or unilateral uniform joint space of less than 2 mm (2% or 0%, respectively), erosions (2%), and intraarticular ankylosis (0%).
Adult↗
Pigmented villonodular synovitis of synovial joints: clinical, pathologic, and radiologic features.
The clinical, pathologic, and radiologic features of pigmented villonodular synovitis of large synovial joints are presented. The typical plain-film presentation of this unusual entity is a noncalcified capsular soft-tissue mass of the knee, without bony abnormalities. When pigmented villonodular synovitis occurs in other joints, it is often accompanied by cystic bone erosions. This important radiographic finding might mislead one to an improper diagnosis of neoplasia or infection. This review reveals insufficient emphasis in the radiologic literature on the high incidence of bone lesions in joints affected by pigmented villonodular synovitis. A mechanism for the development of bone cysts is proposed. Clinical, pathologic, radiologic, and therapeutic considerations are discussed.
Adult↗
Pigmented villonodular synovitis of the shoulder: radiologic-pathologic assessment.
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Aged↗
Skeletal changes in neuromuscular disorders mimicking juvenile rheumatoid arthritis and hemophilia.
Seven patients with neuromuscular disorders were examined, including one with cerebral palsy, one with Duchenne muscular dystrophy, two with paraplegia, and three with poliomyelitis; all exhibited skeletal changes mimicking those found in juvenile rheumatoid arthritis and hemophilia. These findings included apparent overgrowth of the epiphyses, periarticular osteoporosis, and joint-space narrowing in seven subjects; accentuation of the trabecular pattern in six; gracile bones and soft-tissue wasting in five; tibiotalar slant in two; and premature epiphyseal closure in one. Changes in osseous vascular dynamics and the debilitation or immobilization found both in patients with neuromuscular disorders and those with arthritis may help explain these overlapping findings. While the clinical distinction between the neuromuscular and arthritic disorders is straightforward, the similarity in radiographic appearance has received little attention. If the clinical history is inadequate, this may result in confusion or misinterpretation by the radiologist. In the absence of more specific findings, such as articular erosions or erosions of the femoral intercondylar notch, the differential diagnosis may be mistakenly limited to juvenile rheumatoid arthritis and hemophilia. In such cases, the neuromuscular disorders should also be considered in the differential diagnosis.
Adolescent↗
Methods of assessing radiographic change in rheumatoid arthritis.
The first attempt at standardization in the evaluation of rheumatoid arthritis was reported by Steinbrocker in 1949. Subsequently, Kellgren in the late 1950s, Sharp in 1971, and Larsen in 1973 reported detailed techniques for semiquantitative evaluation of radiographic changes and indicated that joint films may be the most accurate and reproducible basis for assessing the severity and progression of rheumatoid arthritis. High-resolution magnification radiography, achieved by optical magnification of fine-grain film or direct radiographic magnification, has proved particularly valuable for the reliable and sensitive evaluation of articular abnormalities in arthritis. Studies have supported the clinical usefulness of these techniques in assessing early rheumatoid arthritis. A semiquantitative radiographic approach recently used in a multicenter clinical trial is illustrated herein. Results indicate a high interobserver correlation for grades of erosion and joint-space narrowing. The sensitivity with which observers graded the findings, however, varied among observers despite the use of reference standards. There was poor correlation among observers for assessing changes in grade with time so that evaluation of clinical response was limited. Observations from this analysis provide the basis for improved methods in the design of clinical therapeutic trials.
Arthritis, Rheumatoid↗