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Biomedical subjects

C W Hayes

Publications and source records attributed to C W Hayes.

At least 37 records · Page 2Linked to original sources
PubMed1997

Current concepts in imaging of the pelvis and hip.

Over the past decade, imaging evaluation of orthopedic conditions of the pelvis and hips has become increasingly complex. Although the conventional radiograph remains the initial examination of choice, the decision between secondary tests, such as computed tomography, MR imaging, or scintigraphy is far from clear. A thorough understanding of current imaging technology is necessary for the clinician to choose the most appropriate examination for a given situation. This article reviews the current status of orthopedic imaging in the areas of acute trauma, stress injuries, osteonecrosis, arthropathies, tumors, and interventional imaging.

Arthritis↗
PubMed1996

Dry taps and what to do about them: a pictorial essay on failed arthrocentesis of the knee.

PURPOSE: To determine and illustrate the causes of unproductive arthrocentesis of the knee. PATIENTS AND METHODS: Consecutive patients were studied who had inflammatory (rheumatoid or psoriatic) arthritis affecting the knees and experienced unproductive arthrocentesis during a randomized, controlled trial. Magnetic resonance imaging (MRI) was used, supplemented first by intravenous gadolinium contrast and subsequently by manual mixing of the diffused contrast to outline the furthest possible penetration of contrast within the joint cavity. RESULTS: In 4 out of 5 patients studied, failed arthrocentesis was due to combinations of inspirated joint fluid too viscous to be withdrawn or to mix with contrast, adipose tissue, and lipoma arborescens (thickened synovium with fat replacement). One MRI exam was normal. More free synovial fluid was imaged on the lateral side. CONCLUSIONS: Failure to aspirate synovial fluid from the knee is explicable to anatomic terms; in particular, fluid viscosity and lipoma arborescens play a role in chronic effusions. Although surface anatomic landmarks for knee arthrocentesis may be more visible medially, the lateral approach is more likely to yield fluid for synovial analysis in difficult cases. Internal medicine trainees should be taught the lateral approach.

Adipose Tissue↗
PubMed1996

Magnetic resonance imaging of the musculoskeletal system. II. The hip.

Magnetic resonance (MR) imaging of the hip joint and adjacent structures can provide valuable information under many clinical circumstances. After plain radiography, MR imaging is arguably the modality of choice for the detection of osteonecrosis, occult fractures, primary and secondary neoplasms, and in the assessment of some soft tissue abnormalities. The accuracy of MR imaging is dependent on technical factors, such as magnet field strength, surface coils, and sequence selection. Low resolution MR images generally are satisfactory for screening for osteonecrosis and for the evaluation of large bone or soft tissue abnormalities. Tailoring an examination with high resolution images, specialized sequences, or contrast may add useful information, particularly if a detailed evaluation of the joint is desired. Tailoring of the examination by an experienced radiologist requires adequate clinical information, so communication between the referring physician and radiologist is crucial for optimal results. Finally, MR imaging and radiographs are complementary examinations; MR images of the hip should not be interpreted without having recent radiographs available for comparison.

Bone Neoplasms↗
PubMed1996

Bowstring injury of the flexor tendon pulley system: MR imaging.

OBJECTIVE. The flexor tendon pulley system is often ruptured when a flexed finger is forcibly extended. In the acute phase, soft-tissue swelling and pain often make clinical evaluation difficult. These pulleys are not constantly visualized on MR imaging. Rupture of the pulley system can be inferred by observing bow stringing of the underlying flexor tendons when MR imaging is obtained with the finger in flexion. Our objective is to describe the flexor tendon pulley system and present our MR technique.

Finger Injuries↗
PubMed1996

The magic angle effect in musculoskeletal MR imaging.

The "magic angle" effect in magnetic resonance (MR) imaging is caused by changes in the dipolar interactions between water hydrogen protons that are loosely bound along collagen fibrils in organized tissue such as tendon or articular cartilage. When tendons are aligned at 55 degrees to the main magnetic field, the T2 relaxation time is lengthened, causing focal increased signal on short echo time MR images. Tendons in the ankle, wrist, and rotator cuff of the shoulder are common sites to observe this effect. Distinguishing magic angle effect from pathologic signal abnormalities due to degeneration or partial tears requires close comparison between T1- and T2-weighted images, as well as evaluation for secondary signs of injury such as tendon thickening or associated fluid.

Artifacts↗
PubMed1994

Vertebral pseudoarthrosis associated with diffuse idiopathic skeletal hyperostosis.

Diffuse idiopathic skeletal hyperostosis is an ossifying diathesis that commonly affects the vertebral skeleton. Spinal ankylosis can occur, predisposing the spine to abnormal stresses and fracture. Fracture through an ankylosed segment with continued motion at the site of fracture can result in pseudoarthrosis. Pseudoarthrosis can also develop at the junction of the fused and mobile spine secondary to chronic abnormal stresses. This complication is manifest radiographically by single-level intervertebral disc space destruction, vertebral endplate erosions, marked vertebral sclerosis, and large osteophytes. The radiographic manifestations can mimic infective spondylitis or neuropathic changes.

Aged↗
PubMed1994

MRI of the patellofemoral joint.

In routine MRI of the knee, less attention frequently is paid to the patellofemoral joint and its surrounding structures than to the menisci and ligaments. This article reviews MRI of common abnormalities of the anterior aspect of the knee. Chondromalacia patellae, pathological softening of the patellar cartilage, can be diagnosed with reasonable accuracy with MRI using standard sequences. Abnormalities of alignment can be assessed grossly on static images, but more sophisticated evaluation of patellofemoral tracking requires the kinematic technique. Other traumatic or overuse injuries involving the extensor mechanism of the knee, such as the quadriceps and patellar tendons, are also reviewed briefly.

Cartilage Diseases↗
PubMed1994

Easily missed injuries around the knee.

Most fractures around the knee are easily detected on high-quality radiographs. However, some fractures and musculotendinous and ligamentous injuries have subtle findings and may be difficult to detect even with optimal images; these injuries include tibial plateau fractures, Segond fractures, stress fractures, fibular head fractures and dislocations, injuries to the patella and extensor mechanism, and Salter type fractures. Clinically suspected tibial plateau fractures unseen on standard views may be seen on tangential or tunnel projections. Segond fractures usually have a characteristic appearance on anteroposterior radiographs but occasionally are seen only on tunnel views. Stress fractures of the proximal tibia may be accompanied by a vague band of increased sclerosis or endosteal callus on either side of the epiphyseal scar. Correct diagnosis of fibular head dislocations requires clinical suspicion, since these injuries often are not recognized on initial radiographs. Careful evaluation of the congruity of the tibiofibular joint on the lateral projection is the key to diagnosis. Vertical patellar fractures are often nondisplaced and are best evaluated with sunrise or Merchant views; avulsion fractures from the proximal or distal poles, with lateral views; and osteochondral fractures, with sunrise or internal oblique views. Salter I injuries can be visualized on oblique and anteroposterior views obtained with stress applied to the knee. Some occult Salter I fractures are diagnosed on follow-up radiographs, which show periosteal reaction. Imaging modalities other than radiography are rarely needed to diagnose fractures but are useful for evaluating the extent of displacement or confirming soft-tissue injuries.

Fractures, Bone↗
PubMed1994

Musculoskeletal causes of spinal axis compromise: beyond the usual suspects.

The majority of cases of spinal canal compromise are caused by common pathologic conditions, including degenerative spondylosis, infection, trauma, and metastatic disease. However, there are other causes of spinal canal compromise that, though unusual, may be seen in everyday practice. Congenital abnormalities of the spine that may produce spinal canal compromise include the os odontoideum, hemivertebra, diastematomyelia, and achondroplasia. Arthritides and enthesopathies such as rheumatoid arthritis, ankylosing spondylitis, synovial cysts of the facet joint, calcium pyrophosphate dihydrate deposition or hydroxyapatite deposition, and ossification of the posterior longitudinal ligament or ligamentum flavum may lead to narrowing of the spinal canal. Primary spinal tumors and tumorlike lesions such as hemangioma, aneurysmal bone cysts, osteochondroma, and osteoblastoma may also cause spinal canal stenosis. Finally, Paget disease of bone may compromise the spinal cord. Radiologists should be aware of these unusual musculoskeletal causes of spinal canal compromise and their radiologic and clinical features.

Humans↗
PubMed1993

MR imaging of bone marrow edema pattern: transient osteoporosis, transient bone marrow edema syndrome, or osteonecrosis.

The bone marrow edema (BME) pattern of signal intensity changes on magnetic resonance (MR) images (decreased on T1-weighted and increased on T2-weighted) is a nonspecific finding encountered with several entities, including transient osteoporosis of the hip, transient BME syndrome, osteonecrosis, trauma, infection, and infiltrative neoplasm. Transient osteoporosis, an unusual but distinct syndrome characterized by self-limited pain and radiographically evident osteopenia, can be distinguished from other causes of the BME pattern, particularly osteonecrosis, on the basis of clinical findings and the development of radiographically evident focal osteopenia within 8 weeks after the onset of pain. This is an important distinction, since all patients with transient osteoporosis recover completely, without intervention. The term transient BME syndrome can be used to describe any patient in whom a reversible BME pattern is seen on MR images. Although the transient BME syndrome is also self-limited and quite likely related to transient osteoporosis, the authors believe that to avoid confusion, this nonspecific term should be reserved only for patients who do not develop radiographically evident osteopenia.

Adult↗
PubMed1993

Normal anatomy and magnetic resonance appearance of the knee.

This article discusses the normal magnetic resonance (MR) appearance, functional anatomy, and biomechanics of the knee joint. Technical considerations of MR imaging of the knee are covered first: coil selection, positioning, and pulse sequences. Useful sequences for both routine examinations and specific clinical situations are suggested. This is followed by a discussion of the biomechanics and functional anatomy of the knee. The typical MR appearance of various key structures in the knee is discussed. The final section of the article is an atlas of normal MR anatomy of the knee, covering the sagittal, coronal, and axial planes.

Biomechanical Phenomena↗
PubMed1993

Miscellaneous lesions of bone.

There are several tumors and tumorlike entities of bone that do not easily fit into the specific classifications provided elsewhere in this issue. In this article, several seemingly unrelated entities are discussed, including cystic diseases of bone (simple bone cysts and aneurysmal bone cysts), Langerhans' cell histiocytosis, benign and malignant vascular tumors of bone, and adamantinoma of long bone and its relationship to osteofibrous dysplasia.

Bone Cysts↗
PubMed1992

Evaluation of articular cartilage: radiographic and cross-sectional imaging techniques.

Many diagnostic modalities may be used to evaluate articular cartilage. Plain radiography remains the preferred initial study for cartilage evaluation, although even specialized views such as weight-bearing, tunnel, and flexion lateral projections are insensitive in the detection of early cartilage loss. Compared with newer modalities, conventional arthrography has limited capacity for the assessment of cartilage. Computed tomography performed after intraarticular injection of contrast material (ie, CT arthrography) has improved accuracy but is essentially limited to the axial plane. Magnetic resonance (MR) imaging, with its superb soft-tissue contrast and multiplanar capabilities, has shown promise in depicting articular cartilage. Cartilage is best depicted when an "arthrogram effect" is present, achieved with T2-weighted spin-echo imaging, with some gradient-echo pulse sequences, and when intraarticular contrast material is used. If performed with such techniques, MR imaging is the method of choice for evaluating specific cartilage loss, osteochondritis dissecans, and other osteochondral abnormalities.

Arthrography↗
PubMed1992

Misleading aggressive MR imaging appearance of some benign musculoskeletal lesions.

After plain radiography has been performed, magnetic resonance (MR) imaging is considered the modality of choice for the evaluation of suspected musculoskeletal lesions because of its exquisite sensitivity to changes in the signal intensity of marrow and soft tissue. That sensitivity, however, may lead to an overestimation of the aggressiveness and extent of some benign bone lesions, particularly in children. Such lesions include chondroblastoma, osteoid osteoma, eosinophilic granuloma, and stress fractures. Potentially misleading MR features commonly seen include prominent marrow edema, soft-tissue edema, and apparent mass effect adjacent to the bone lesion. Features that these lesions have in common that may explain the MR findings include associated inflammatory reactions caused by the lesions and their occurrence in childhood, when the periosteum is more loosely attached. Knowledge of the potential pitfalls encountered with MR imaging may help explain the discrepancy between the radiographic and MR appearances of these benign lesions and avoid misplaced reliance on MR imaging for a diagnosis. Radiography remains the single most valuable modality in determining a differential diagnosis for bone lesions.

Adolescent↗
PubMed1991

Seat belt injuries: radiologic findings and clinical correlation.

The seat belt syndrome consists of skeletal, soft-tissue, and visceral injuries associated with use of two- and three-point restraints in patients involved in motor vehicle accidents. Skin abrasions of the neck, chest, and abdomen--the classic seat belt sign--indicate internal injury in 30% of cases. Neck abrasions are associated with injuries to the carotid artery, larynx, and cervical spine; chest abrasions, with fractures of the sternum, ribs, and clavicles and injuries to the heart and thoracic aorta; and abdominal abrasions, with mesenteric tears, bowel perforation and hematoma, Chance fractures, and injuries to the abdominal aorta. The seat belt sign should prompt a diligent search for related injuries.

Abdominal Injuries↗