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Biomedical subjects

L L Seeger

Publications and source records attributed to L L Seeger.

At least 55 records · Page 3Linked to original sources
PubMed1994

Case report 828: Plexiform neurofibroma of the tibial nerve invading the medial and lateral gastrocnemius muscles and plantaris muscle.

A 5-year-old boy presented with a several-year history of swelling of his calf and muscular weakness. MRI demonstrated abnormal signal and diffuse enlargement of the gastrocnemius muscle. Pathological examination revealed plexiform neurofibroma, and the diagnosis of neurofibromatosis was subsequently made. The manifestations of neurofibromatosis and the peripheral nerve sheath tumors encountered in this disease are discussed. Special attention is paid to the MR features of the plexiform neurofibroma which is characteristic of this disorder.

Child, Preschool↗
PubMed1994

Labrocapsular ligamentous complex of the shoulder: normal anatomy, anatomic variation, and pitfalls of MR imaging and MR arthrography.

Magnetic resonance (MR) imaging is a useful modality for evaluating the labrocapsular ligamentous complex (LCLC) of the shoulder. MR arthrography is an important and occasionally indispensable supplementary modality for accurate differentiation between normal and deranged glenohumeral joints. Because of the joint distention that occurs during MR arthrography, it is especially helpful in detecting subtle capsular derangement, as occurs in patients with atraumatic instability. Also, some of the pitfalls associated with MR imaging of the LCLC are less likely to occur with MR arthrography. Radiologists should look for several key abnormalities when evaluating MR images of the shoulder: an anterior or posterior Bankart lesion; a Hill-Sachs defect; a tear of the rotator cuff, glenoid labrum, or superior labrum-biceps tendon attachment; and loose bodies. Knowledge of normal anatomy, normal variations, and pitfalls in image interpretation related to evaluation of the LCLC will help the radiologist accurately detect debilitating derangements associated with glenohumeral instability.

Humans↗
PubMed1994

Anterior cruciate ligament tear: indirect signs at MR imaging.

PURPOSE: To establish the sensitivity and specificity of indirect signs at magnetic resonance (MR) imaging of anterior cruciate ligament (ACL) tear. MATERIALS AND METHODS: MR images of the knees of 89 consecutive patients (54 with torn and 35 with normal ACLs) were reviewed. RESULTS: The indirect signs were as follows (first percentage is sensitivity; the second, specificity): angle between lateral tibial plateau and ACL less than 45 degrees (90%, 97%); angle between Blumenstaat line and ACL more than 15 degrees (89%, 100%); bone contusions in lateral compartment (54%, 100%); position of posterior cruciate ligament (PCL) line (52%, 91%); PCL angle less than 107 degrees (52%, 94%); PCL bowing ratio more than 0.39 (34%, 100%); posterior displacement of lateral meniscus more than 3.5 mm (44%, 94%); anterior displacement of tibia more than 7 mm (41%, 91%); and lateral femoral sulcus deeper than 1.5 mm (19%, 100%). CONCLUSION: Because the specificity is high, the presence of indirect signs corroborates the diagnosis of ACL tear. Because the sensitivity is low, the absence of these signs does not exclude the diagnosis of ACL tear.

Adult↗
PubMed1994

Inter- and intraobserver variation in staging patients with proven avascular necrosis of the hip.

Diagnosis and treatment of avascular necrosis of the hip has long been predicated on the evaluation of plain radiographs, though other modalities (such as magnetic resonance imaging) are being increasingly used to aid in this evaluation. The Ficat classification is commonly used to assess plain radiographs and to help determine what treatment is appropriate for a given patient. It also is used to help evaluate patient outcome after surgical or nonsurgical treatment. This study was designed to evaluate the adequacy of plain radiographs in the evaluation of avascular necrosis of the hip. The plain radiographs of 25 hips with avascular necrosis were analyzed on 3 occasions by 6 readers (450 total readings). A clinically significant difference in radiographic staging was defined as a Stage I or II reading of the radiographs of a given hip on 1 reading and a separate reading of the same radiographs as Stage III or IV. By this definition, interobserver variability for the first reading resulted in clinically significant differences in 10 (40%) of the 25 hips. Intraobserver variability resulted in clinically significant differences for 10 (40%) of the 25 hips as well. The most experienced readers in the study (a total joint specialist and a musculoskeletal radiologist) were consistent internally in their readings in 90% of cases, and had a clinically significant difference in only 1 case (1%); however, these same 2 readers disagreed with one another on the staging of 9 (36%) of 25 hips, with 4 (16%) of 25 hips having a clinically significant difference in readings.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1994

True three dimensional stereographic display of 3D reconstructed CT scans of the pelvis and acetabulum.

Fractures of the acetabulum can cause the pelvis to shatter into a wide array of complex configurations which can be difficult to fully delineate preoperatively. In addition to plain radiography and standard computed tomography, technology now allows the reconstruction of magnetic resonance imaging (MRI) and computed tomography (CT) data into virtual objects; three dimensional (3D) representations of anatomy which exist only within the computer memory. Printouts and photographs of 3D reconstructions provide another level of anatomic information to the orthopaedic surgeon. However, current standard displays such as computer and video screens and photographic and radiographic film are all two dimensional (2D) modalities. Displaying 3D reconstructions in this standard 2D fashion, inescapably robs the images of up to one third of the information contained within them--all the true depth information which is the essence of 3D. Shading techniques and perspective have both been utilized to simulate depth, but true depth is still lacking. Recently, the authors have begun using a technique of computerized 3D reconstruction and recording which provides a true 3D display of the reconstructed images. The resultant gain in image realism is profound, somewhat similar to hearing full stereo audiophonic recording compared to monophonic, or to seeing in color rather than black and white. The image generation and display process is a computerized mathematical adaptation of the photographic technique of stereophotography. Once in place, the technique is relatively simple to use and can be achieved in several ways with a minimum of additional hardware. Potential benefits lie in the method's ability to convey, in one 3D display, the true 3D, spatial anatomic configuration of the imaged pelvis. The methods described are common to those forming the fundamental basis for virtual reality imaging. Current users of some 3D reconstruction systems can now easily generate images which can be viewed with all of the depth information restored, into a true 3D display.

Acetabulum↗
PubMed1994

Imaging evaluation of osteomyelitis.

Bone infection, or osteomyelitis, is a common medical problem that is often difficult to diagnose. Osteomyelitis is not unusual in diabetic patients with foot ulcers and bedridden patients with decubitus ulcers--populations where diagnosis is especially difficult. Spinal osteomyelitis and septic arthritis require early diagnosis in order to avoid permanent debilitating consequences. Regardless of the clinical setting, imaging plays an important role in establishing the diagnosis and directing treatment. A variety of imaging modalities may be used, including plain radiography, radionuclide imaging, computed tomography (CT), and magnetic resonance imaging (MRI). Decisions regarding the best imaging modality can be challenging and should reflect the location of the suspected infection and associated illness or bony disorders.

Adult↗
PubMed1994

Pulmonary metastasis of benign giant cell tumor of bone. Six histologically confirmed cases, including one of spontaneous regression.

Benign giant cell tumor of bone, despite being classified as benign, has the unusual ability to metastasize. Metastasis of such a tumor has been thought to be rare, with only approximately 50 such cases having been reported. However, as awareness of the metastatic potential of these tumors has increased, and methods of detection have improved, metastasis of benign giant cell tumor has been increasingly recognized. Six patients with pulmonary metastasis of giant cell tumor have been treated at a Los Angeles hospital since 1980. This represents 9.1% of all patients treated for benign giant cell tumor of bone over the same period at this institution, a higher rate than that encountered in previously published series. The early detection and treatment of this tumor is important, because those with complete resection of tumor have the best prognosis. The nature of these pulmonary metastases remains unpredictable, however, as evidenced by two of the cases in this series: one of spontaneous regression, and another of death caused by pulmonary failure.

Adolescent↗
PubMed1994

Hydroxyapatite-coated distal femoral replacements. Preliminary results.

A custom-designed, hydroxyapatite-coated distal femoral replacement was developed and implanted in five individuals at the authors' hospital. The indications for this type of prosthesis were a multiply failed cemented endoprosthesis in two individuals; a revision of an infected, previously cemented endoprosthesis in another; a primary low-grade sarcoma in a fourth, and a stage III giant cell tumor in the final individual. Mean follow-up time was 3.3 years (range, 2.9-3.5 years). The functional results, based on the Musculoskeletal Tumor Society (MSTS) criteria, were excellent in one patient (20%) and good in four patients (80%). Musculoskeletal Tumor Society functional scores ranged from 25 to 35 (mean, 29.8). No patient had thigh pain. All the femoral components appeared well fixed on radiographic evaluation. These preliminary results indicate that a hydroxyapatite-coated distal femoral replacement may represent a viable alternative to a cemented endoprosthesis for aggressive benign lesions and low-grade sarcomas requiring resection. In addition, it appears to be a viable solution for failed cemented endoprostheses in individuals who have survived their disease.

Adolescent↗
PubMed1994

Magnetic resonance imaging of glenohumeral instability.

Glenohumeral instability refers to subluxation or dislocation of the glenohumeral joint. This painful disorder is particularly common in the athletic population, and the individual with instability may present with a variety of clinical complaints. This paper addresses current theories regarding the pathophysiology of glenohumeral instability and illustrates magnetic resonance findings that can assist in diagnosis and treatment planning.

Athletic Injuries↗
PubMed1993

Imaging shoulder impingement.

Appropriate imaging and clinical examinations may lead to early diagnosis and treatment of the shoulder impingement syndrome, thus preventing progression to a complete tear of the rotator cuff. In this article, we discuss the anatomic and pathophysiologic bases of the syndrome, and the rationale for certain imaging tests to evaluate it. Special radiographic projections to show the supraspinatus outlet and inferior surface of the anterior third of the acromion, combined with magnetic resonance images, usually provide the most useful information regarding the causes of impingement.

Humans↗
PubMed1993

Case report 815: Tear of the rotator interval.

Rotator interval tears are an uncommon, but clinically important subtype of rotator cuff tear. As MRI assumes an ever increasing role in the imaging evaluation of the painful shoulder, radiologists must be aware of this entity and appreciate the difficulty in diagnosing these tears with MRI. Differentiation of a true rotator interval tear from normal synovium and capsule in this space is most likely not possible with MRI, and symptoms may be referred and misleading. It is therefore important to correlate the MR findings with the clinical history and physical examination.

Aged↗
PubMed1993

Spring ligament of the ankle: normal MR anatomy.

The plantar calcaneonavicular or spring ligament is visualized inconsistently and incompletely on routine MR images of the foot. This ligament is a vital stabilizer of the longitudinal arch of the foot, providing support for the head of the talus, which rests on the ligament's central portion. Laxity or rupture of the spring ligament permits plantar flexion of the talus. This motion results in valgus alignment of the calcaneus and a flatfoot deformity (pes planovalgus). Laxity or rupture of the spring ligament can develop in cases of chronic dysfunction of the posterior tibial tendon. In rupture of the posterior tibial tendon, surgical management may include plication of the spring ligament in addition to repair or reconstruction of the tendon to stabilize the medial column of the foot. Thus, the status of the spring ligament can be a significant consideration in preoperative planning. This pictorial essay illustrates the normal MR anatomy of the spring ligament, the planes of imaging required for optimal depiction of the ligament, and the neighboring structures with which the ligament can be confused.

Ankle↗
PubMed1992

Case report 715. Necrotic giant cell tumor of the femur.

We present a giant cell tumor of the distal end of the femur that exhibited unusual diaphyseal extension and atypical MRI features. MRI demonstrated differing zonal signal characteristics in the distal metaphyseal/epiphyseal versus the diaphyseal components of the tumor. It also depicted an irregular, proximal tumor margin with an unusual, enhancing, peripheral zone. The atypical MRI features may be related to the unusual finding at pathological examination of an almost entirely necrotic giant cell tumor. This massive necrosis may illustrate a stage in the evolution of some giant cell tumors to fibrous histiocytoma-like variants of giant cell tumor or to conventional, benign fibrous histiocytoma of bone.

Adult↗
PubMed1992

Case report 707: Hemorrhagic Baker's cyst of the right calf.

A 50-year-old woman with juvenile rheumatoid arthritis presented with painful swelling of the right calf. Roentgenograms, sonograms, magnetic resonance images, and arthrograms were obtained. A diagnosis of hemorrhagic Baker's cyst was made, and surgical excision was performed. The etiology, clinical features, and radiological evaluation of simple and complicated Baker's cysts are discussed and the differential diagnosis considered.

Diagnosis, Differential↗
PubMed1992

Diagnosis of soft-tissue masses with MR imaging: can benign masses be differentiated from malignant ones?

A blinded, retrospective review of 83 soft-tissue masses (49 benign and 34 malignant) was performed to evaluate the ability to distinguish benign from malignant soft-tissue masses with magnetic resonance (MR) imaging. The correct histologic diagnosis was reached in 31% of cases by one reader and in 16% of cases by the second reader. Mean sensitivity was 50% for benign masses and 80% for malignant masses. The majority of both benign and malignant masses had inhomogeneous signal intensity and at least partially irregular borders. Malignant masses uncommonly had smooth borders and homogeneous signal intensity. MR imaging can be used to evaluate the extent of soft-tissue masses, but most masses will require biopsy to determine if they are benign or malignant.

Adult↗
PubMed1992

MR imaging of joints: analytic optimization of GRE techniques at 1.5 T.

To clarify the choice of imaging parameters for optimal gradient-recalled echo MR scanning of joints, we analyzed the behavior of contrast-to-noise and signal-to-noise ratios for spoiled (i.e., fast low-angle shot [FLASH] or spoiled GRASS) and steady-state (i.e., gradient-recalled acquisition in the steady state [GRASS] or fast imaging with steady precession) techniques at 1.5 T. The analysis is based on tissue characteristics derived from spin-echo measurements of hyaline cartilage and synovial fluid signal in the patellofemoral joints of 11 volunteers. Separate analysis of contrast-to-noise and signal-to-noise ratios for multiplanar (long TR) acquisitions shows that these parameters are each improved compared with single-slice methods. At TRs greater than 250 msec, there is no significant difference in the contrast behavior of FLASH and GRASS. For optimal contrast-to-noise ratio (synovial fluid-cartilage), the best multiplanar sequence (for TE less than 23 msec) is with a short TE and a large flip angle (e.g., 400/9/73 degrees [TR/TE/flip angle]). If a single-scan or three-dimensional technique is desired, than a GRASS sequence at minimal TR and TE and intermediate flip angle (18/9/32 degrees) is best. For optimal signal-to-noise ratio (for both synovial fluid and hyaline cartilage), the best multiplanar sequence uses a short TE and an intermediate flip angle (e.g., 400/9/30 degrees). If a short TR, high signal-to-noise technique is desired, then GRASS (18/9/13 degrees) is superior to FLASH.

Cartilage, Articular↗