Search PubMed⌕ Search

Biomedical subjects

L L Seeger

Publications and source records attributed to L L Seeger.

At least 91 records · Page 5Linked to original sources
PubMed1989

Magnetic resonance imaging of the hindfoot.

This article demonstrates normal anatomy of the foot and ankle as visualized with magnetic resonance imaging (MRI) in the sagittal, axial, and coronal planes. Additionally, selected cases chosen from our experience with more than 100 clinical scans are shown to highlight the primary areas in which we have found MRI to be clinically useful: bone marrow abnormalities, especially osteomyelitis and osteonecrosis, soft tissue injuries and masses, and cases in which metallic fixators make CT evaluation problematic.

Adult↗
PubMed1989

Magnetic resonance imaging of the shoulder.

Magnetic resonance imaging (MRI) is proving to be an effective means for evaluating the shoulder. The use of a surface coil and high resolution scanning techniques have allowed detailed analysis of the normal anatomy of the shoulder. When evaluating for shoulder pathology, the choice of imaging plane and pulse sequencing will be determined by the suspected pathology. In patients with impingement syndrome, subacromial bursitis, supraspinatus tendinitis, and supraspinatus tendon tear can be differentiated, and the offending component of the subacromial are traumatizing these soft tissues can be identified. MRI is also useful in determining the extent of retraction of the supraspinatus musculotendinous junction and the amount of muscle atrophy in cases of massive, chronic tears. Labral tear or attenuation due to glenohumeral instability can be imaged without the injection of contrast material, and MRI can identify those patients with multidirectional instability. Because of the ability to directly depict bone marrow, MRI is the imaging method of choice for the evaluation of early ischemic necrosis of the humeral head.

Humans↗
PubMed1989

Physical principles of magnetic resonance imaging.

When a nucleus contains either unpaired protons, neutrons, or both, it has angular momentum. This property provides the basis for magnetic resonance imaging (MRI). Because of its abundance in the human body, hydrogen is used for clinical MRI. Within the MR magnet, the atoms are aligned with the magnetic field. The MR signal is generated by subjecting the atoms to radiofrequency (RF) pulsations, and the pulse sequences selected will determine the appearance of the image. The repitition time (TR) is the time between the RF pulses, and the echo time (TE) is the time between the RF pulse and the recording of the signal. T1-weighted images (short TR/short TE) provide the best anatomic detail, but T2-weighted images (long TR/long TE) are often needed to demonstrate pathology. Many unfamiliar artifacts may be encountered on MR images. These can be due to several factors, including inhomogeneities in the magnetic field (for example, those resulting from metallic orthopedic applicances or prior surgery), extraneous RF interference, and motion. Surface coils are commonly used in musculoskeletal MR imaging to improve the quality of the examination by increasing the signal-to-noise ratio over the area of interest.

Humans↗
PubMed1988

Musculoskeletal infection of the extremities: evaluation with MR imaging.

Magnetic resonance (MR) imaging was performed in 17 patients, 11-84 years of age, referred for evaluation of possible osteomyelitis involving the appendicular skeleton. MR imaging permitted successful identification of osteomyelitis in ten patients (four acute, two subacute with Brodie abscess, two chronic, and two acute with septic arthritis) and of cellulitis in the absence of osteomyelitis in four patients, including one with a soft-tissue abscess. Active osteomyelitis was excluded in three patients. Both T1- and T2-weighted spin-echo sequences were needed to evaluate osteomyelitis. T2-weighted images were needed to identify foci of active infection. MR images provided more accurate and detailed information regarding the extent of involvement than did radionuclide bone scans, computed tomographic scans, or standard radiographs. It permitted the differentiation of septic arthritis or cellulitis from osteomyelitis. In this limited series, MR imaging was particularly useful for seeking foci of active infection in areas of chronic osteomyelitis complicated by surgical intervention or fracture.

Abscess↗
PubMed1988

Shoulder instability: evaluation with MR imaging.

Instability of the glenohumeral joint is a common cause of chronic shoulder pain and disability. One or more episodes of subluxation or dislocation may result in a tear, detachment, or attenuation of the glenoid labrum, stripping of the joint capsule from the scapula, or trauma to the tendons or muscles of the rotator cuff. A series of 27 shoulders examined with magnetic resonance (MR) imaging showed changes of glenohumeral instability, which were confirmed with open or arthroscopic surgery. MR imaging was capable of displaying common types of pathologic conditions resulting from instability, including labral trauma, capsular detachment, and retraction of the subscapularis muscle. MR imaging is a valuable diagnostic tool for the evaluation of glenohumeral instability.

Humans↗
PubMed1988

Shoulder impingement syndrome: MR findings in 53 shoulders.

The shoulder impingement syndrome refers to a condition in which the supraspinatus tendon and subacromial bursa are chronically entrapped between the humeral head inferiorly and either the anterior acromion itself, spurs of the anterior acromion or acromioclavicular joint, or the coracoacromial ligament superiorly. As a result, the space for the bursa and tendon is reduced, and repeated trauma to these structures leads to bursitis and rotator cuff injury. Although pain and limitation of motion are common early findings, the diagnosis is often delayed until a complete tear of the rotator cuff has occurred. In an attempt to determine if MR can be used to depict the abnormalities associated with impingement syndrome (subacromial bursitis, supraspinatus tendinitis, and rotator cuff tear), we reviewed 107 MR scans of painful shoulders. Changes consistent with impingement syndrome were found in 53 patients (50%), 32 of whom underwent subsequent arthrography or surgery. MR was found capable of depicting several soft-tissue and bony abnormalities that have been clinically described in impingement syndrome. In regions of inflammation, we found that the supraspinatus tendon and/or the subacromial bursa were compressed by spurs (25 shoulders), capsular hypertrophy of the acromioclavicular joint (six shoulders), and/or low-lying acromion (14 shoulders). While T1-weighted MR imaging was highly sensitive to abnormalities of the supraspinatus tendon, tendinitis could be differentiated from a small tear of the supraspinatus tendon only with T2-weighted imaging. Large, full-thickness tears, especially if chronic, produced characteristic MR findings on both T1- and T2-weighted images. We conclude that MR can be used to detect several abnormalities associated with the shoulder impingement syndrome.

Bursitis↗
PubMed1988

The other arthritides. Roentgenologic features of osteoarthritis, erosive osteoarthritis, ankylosing spondylitis, psoriatic arthritis, Reiter's disease, multicentric reticulohistiocytosis, and progressive systemic sclerosis.

Osteoarthritis may be divided into primary generalized and secondary forms. Primary generalized osteoarthritis is characterized by narrowing of cartilage, marginal osteophytes, and absence of erosions. The most common sites of involvement are the distal interphalangeal joints of the fingers and the first carpometacarpal joint. Secondary osteoarthritis also results in narrowing of cartilage in the absence of erosions, but in regions of mechanical stress. Erosive osteoarthritis affects predominantly the proximal and distal interphalangeal joints, and evolves into bony fusion in 12 to 15 per cent of cases, about the same percentage of interphalangeal bony fusion that occurs in psoriatic arthritis. Ankylosing spondylitis predominates in the axial skeleton where it eventually leads to fusion of the vertebrae and sacroiliac joints. Psoriatic arthritis combines many features of rheumatoid arthritis, in which synovial inflammation predominates, and ankylosing spondylitis, in which ligamentous inflammation predominates. The hands and feet are involved to an equal extent, and in 20 per cent of patients the disorder also involves the sacroiliac joints and spine. Reiter's disease, like psoriatic arthritis, differs from ankylosing spondylitis in its inconstant involvement of the spine and greater involvement of peripheral joints. Reiter's disease differs from psoriatic arthritis in its predominant involvement of the lower limbs, particularly the feet, with relative sparing of the hands and wrists. Multicentric reticulohistiocytosis is a rare disorder in which polyarthritis usually precedes the onset of nodular cutaneous eruptions, a fact that emphasizes the importance of early roentgenologic recognition. The interphalangeal joints are the predominant sites of involvement in the hands, but eventually all of the synovium lined joints become affected, with arthritis mutilans the end result in one third of cases. The erosions are strikingly symmetrical and well circumscribed, and accompanying osteoporosis is disproportionately mild. Progressive systemic sclerosis is characterized by atrophy and dystrophic calcifications in the soft tissues, ultimately leading to joint deformities and resorption of the terminal tufts of the phalanges. Resorption of bone occurs at other sites as well, and marginal erosions may develop in the metacarpophalangeal and interphalangeal joints of the hands.

Arthritis, Reactive↗
PubMed1987

MR imaging of the normal shoulder: anatomic correlation.

The complex anatomy and the requirement to image in the peripheral magnetic field have made the shoulder difficult to examine with MR. However, the use of high-resolution scanning techniques and specialized surface coils has improved the quality of MR images obtained. Seventy-five scans of the shoulders of normal volunteers were correlated with multiplanar cryomicrosections of six cadaver shoulders to study the MR appearance of normal structures. MR was shown to provide excellent depiction of shoulder anatomy.

Cadaver↗
PubMedDate not supplied

Epiphyseal growth arrest lines. MR findings.

We present two cases in which MR exams revealed unusual, low signal intensity lines in the marrow space of epiphyses. These epiphyseal lines were smooth and regular, creating a bone-in-bone appearance. These lines were much more conspicuous on MR than on radiographs, partly because of adjacent alterations in trabecular architecture. A history of prolonged immobilization during childhood in both cases suggests that these lines represent growth arrest lines persisting in the epiphyses.

Adult↗
PubMedDate not supplied

Whole body skeletal imaging with [18F]fluoride ion and PET.

Using our recently reported whole body PET imaging technique, we performed whole body PET studies of the skeletal system with [18F]fluoride ion in 19 patients with a range of malignant and benign skeletal conditions and in 19 normal male volunteers. The technique produces two-dimensional projection images of the entire skeletal system ("a PET bone scan"), in addition to coronal, sagittal, and axial tomographic images of the skeletal system. The tomographic images had a 13% higher lesion detection sensitivity than the projection images. Whole body PET skeletal imaging with [18F]fluoride ion is technically feasible, provides images of excellent quality, and may be coupled with more quantitatively precise kinetic PET [18F]fluoride ion studies (over limited regions of the body) when numerical estimates of skeletal [18F]fluoride ion uptake are desired. The method is potentially useful in clinical applications where the high resolution and numerical precision of PET are of particular value (e.g., in accurately defining the anatomic location and extent of lesions and in assessing changes in bone metabolism on serial studies).

Adult↗
PubMedDate not supplied

Fibrous dysplasia associated with cortical bony destruction: CT and MR findings.

OBJECTIVE: Fibrous dysplasia is a benign disorder of bone that can cause cortical thinning as well as bony expansion. Full-thickness cortical bony destruction, however, typically characterizes more aggressive or malignant lesions of bone. We present three cases of fibrous dysplasia that illustrate this more aggressive and potentially confusing feature. MATERIALS AND METHODS: The findings on radiography and cross-sectional imaging studies are reviewed in three surgically proven cases of fibrous dysplasia that exhibited full-thickness cortical bony destruction. RESULTS: Well-defined cortical perforations without associated periosteal reaction were clearly seen on CT. This finding was suspected on plain radiography in only one of the three cases. A small associated soft tissue mass was detected by MR imaging in this case. Many cortical perforations were seen in the one case of polyostotic fibrous dysplasia. CONCLUSION: Full-thickness cortical bony destruction can be seen in fibrous dysplasia. This finding, which may only be evident on cross-sectional imaging studies, should not by itself alter a diagnostic impression of fibrous dysplasia supported by other radiographic and clinical features.

Adult↗
PubMedDate not supplied

MR findings in peroneal tendonopathy.

OBJECTIVE: The purpose of this presentation is to familiarize the reader with the often subtle findings of peroneal tendon derangement on MRI examination. MATERIALS AND METHODS: We present four patients who were studied with MR (1.5 T) prior to surgical exploration of the peroneal tunnel. All patients had lateral ankle symptoms for > 6 months. Normal MR anatomy and an example of the peroneus quartus tendon are also shown. RESULTS: Surgery revealed two peroneus brevis and three peroneus longus lesions. A "multipartite" appearance of the peroneus tendon on axial MR images, especially when paired with a "flame-shaped" appearance on more distal axial images, indicates a longitudinal tendon split. Both patients with peroneus brevis tendon splits had insufficient superior peroneal retinacula. CONCLUSION: Partial ruptures of the peroneal tendons characteristically take the form of longitudinal tendon splits. Axial MR images through the ankle and hindfoot can help distinguish peroneal tendonitis from longitudinal tendon splits.

Adolescent↗