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Biomedical subjects

D Resnick

Publications and source records attributed to D Resnick.

At least 37 records · Page 2Linked to original sources
PubMed1994

Ossification of the Achilles tendon: imaging abnormalities in 12 patients.

Ossification of the Achilles tendon is a rare clinical entity that is characterized by the presence of an ossific mass contained within the fibrocartilaginous substance of the tendon. Because the radiographic features of this condition have not been documented entirely and the magnetic resonance (MR) imaging findings have not been determined, a review of 16 affected tendons in 12 patients was performed in an attempt to characterize the imaging abnormalities associated with this process. MR imaging was performed in three Achilles tendons which demonstrated thickening of the tendons at the level of the ossifications and a lack of intratendinous signal abnormalities compatible with acute tendinitis. Signal intensity similar to that of bone marrow was present in the ossifications.

Achilles Tendon↗
PubMed1994

The MR appearance of cruciate ganglion cysts: a report of 16 cases.

Intra-articular ganglion cysts arising from the cruciate ligaments are unusual lesions, there being only nine previously reported cases. We report 16 cases and describe their MR appearance. Nine ganglia originated from the posterior cruciate ligament, most often appearing as well-defined multilocular lesions. The seven ganglia arising from the anterior cruciate ligament most often appeared as fusiform cystic lesions extending along and interspersed within the fibers of the ligament. Although uncommon, intra-articular ganglion cysts arising from the knee appear to have a distinctive MR appearance which should allow their correct diagnosis.

Adult↗
PubMed1994

Meniscal ossicle: MR imaging appearance in three patients.

Meniscal ossicles are rare. Radiographically, these ossicles often are mistaken for intra-articular bodies. We evaluated the application of magnetic resonance imaging to determine whether this technique is efficacious in differentiating meniscal ossicles from intra-articular bodies.

Humans↗
PubMed1994

Central (interior) osteophytes of the distal femur. Imaging and pathologic findings.

RATIONALE AND OBJECTIVES: To characterize central osteophytes (COs) of the distal femur, imaging features that enable their differentiation from intra-articular bodies were identified, and the frequency of overlying articular cartilage abnormalities was determined. METHODS: The authors inspected 133 distal femoral specimens and retrospectively reviewed knee radiographs of 48 symptomatic patients and magnetic resonance images of 60 symptomatic patients for presence of COs. The location and imaging features of COs, and their association with marginal osteophytes (MOs), were recorded. Articular cartilage abnormalities, if any, were documented in patients who underwent magnetic resonance imaging. RESULTS: Specimen analysis showed a 41% prevalence of COs, 95% association of COs with MOs, and predominance of large COs in the medial femoral condyle (81%). Radiographic analysis revealed a 9.8% prevalence of COs in the distal femur. Magnetic resonance images demonstrated a 14.3% prevalence of COs, with the majority (73%) accompanied by an overlying cartilage that had abnormal signal intensity or morphology, or both. CONCLUSIONS: Central osteophytes are a common finding in the distal femur. Based on their location and cortical continuity with the underlying bone, most COs can be differentiated from intra-articular bodies.

Adult↗
PubMed1994

MR imaging of injuries of the extensor mechanism of the knee.

Rupture of the extensor mechanism of the knee must be diagnosed early in order to be successfully treated. However, the clinical signs of this condition may be concealed by hematoma or hemarthrosis. The noninvasiveness and accuracy of magnetic resonance (MR) imaging make it useful in detection of such ruptures. Normal quadriceps tendons have a laminated appearance on MR images. The normal patella has signal intensity similar to that of bone marrow and cortex, while normal patellar tendons have homogeneous low signal intensity with all sequences. Patellar fractures, bone bruises, and avulsion of the tibial tubercle manifest as changes in marrow signal intensity. The laminated configuration of the quadriceps tendon allows distinction between partial and complete tears; both may be accompanied by edema and hemorrhage, which manifest as increased signal intensity on T2-weighted images. Ruptures of the patellar tendon also manifest as increased signal intensity on T2-weighted images.

Humans↗
PubMed1994

Hill-Sachs lesion and normal humeral groove: MR imaging features allowing their differentiation.

PURPOSE: To present a method of differentiating Hill-Sachs lesions from the anatomic groove in the posterolateral humeral head with use of magnetic resonance imaging. MATERIALS AND METHODS: A 360 degrees reference about the humeral head was established to define the locations of Hill-Sachs lesions and the anatomic groove on transaxial images. The extension of each finding along the longitudinal humeral axis was noted. Eight cadaveric specimens were sectioned and similarly analyzed. RESULTS: The locations of Hill-Sachs lesions and the anatomic groove in the circular reference frame were statistically significantly different (P < .001), yet their respective ranges overlapped. Along the longitudinal humeral axis, there was no overlap between the respective ranges of location (P < .001). CONCLUSION: A Hill-Sachs lesion is best differentiated from the anatomic groove by means of its more cephalic position along the longitudinal humeral axis.

Adult↗
PubMed1994

MR imaging of articular cartilage: current status and future directions.

Advances in surgical and pharmacologic techniques for treating and preventing chondral abnormalities are creating a demand for an accurate, noninvasive imaging method to evaluate articular cartilage. The most promising technique is MR imaging, but its exact role in this evaluation remains undefined. This article reviews the MR appearance of normal and abnormal articular cartilage and the various pulse sequences that can be used to evaluate chondral lesions. It also briefly discusses possible future directions for MR imaging of articular cartilage.

Animals↗
PubMed1993

Secreted extracellular domains of macrophage scavenger receptors form elongated trimers which specifically bind crocidolite asbestos.

Macrophage scavenger receptors, which have been implicated in the development of atherosclerosis and other macrophage-mediated events, are trimeric integral membrane glycoproteins whose extracellular domains have been predicted to include alpha-helical coiled-coil, collagenous and globular structures. To elucidate further the structural and functional properties of these receptors, we generated transfected Chinese hamster ovary cells which express secreted extracellular domains of the type I and type II bovine scavenger receptors and developed a solid-phase bead-binding assay to assess their ligand-binding properties. The secreted receptors exhibited the distinctive high-affinity, broad polyanionic ligand-binding specificity and the pH dependence of binding which characterize the membrane-anchored cell-surface forms of the receptors. Both the type I and type II secreted receptors were trimeric glycoproteins comprising disulfide-linked dimers and noncovalently associated monomers. Gel filtration and glycerol-gradient centrifugation established that the type II trimers were highly elongated and did not associate into higher order oligomers at the low concentrations used in these experiments. Crocilodite asbestos, which is phagocytosed by alveolar macrophages and can cause asbestosis and mesothelioma, bound efficiently to secreted type I receptors and less well to the type II receptors. This binding was specific in that it was competed by a variety of well established scavenger receptor ligands but not by negative controls. These studies have identified a new type of insoluble scavenger receptor ligand, and have raised the possibility that scavenger receptors may play a role in mediating the physiological and pathological interactions of inspired particles with alveolar macrophages.

Amidohydrolases↗
PubMed1993

The collagenous domains of macrophage scavenger receptors and complement component C1q mediate their similar, but not identical, binding specificities for polyanionic ligands.

Macrophage scavenger receptors have been implicated in the development of atherosclerosis and other macrophage-associated functions, including host defense. The mechanism by which these receptors bind a wide array of polyanions, such as acetylated low density lipoprotein (Ac-LDL), with high affinity has not yet been elucidated; however, it has been proposed that the positively charged extracellular collagenous domain of scavenger receptors plays a key role in ligand binding. To test this proposal, we generated truncation mutants of the bovine and murine scavenger receptors and studied their expression in transiently transfected COS cells. These mutants contain only 8 (bovine) or 5 (murine) of the 24 Gly-X-Y tripeptide repeats found in the collagenous domains of the full-length receptors. Immunochemical analyses established that the truncation of the bovine scavenger receptor did not interfere significantly with its synthesis, trimerization, post-translational processing, intracellular transport, surface expression, or stability. However, unlike their full-length counterparts, the truncated bovine and murine receptors were unable to bind Ac-LDL. Thus, the collagenous domain was necessary for normal ligand binding. In addition, cotransfection of the expression vector for the truncated bovine scavenger receptor with that for the full-length receptor resulted in dramatically reduced activity of the full-length construct (dominant negative effect). A ligand bead-binding assay was used to show that the isolated collagenous domain from a different protein, complement component C1q, could bind a wide variety of polyanions with a specificity which was similar, but not identical, to that of scavenger receptors. These results suggest that the collagenous domain of the scavenger receptor is both necessary and sufficient to determine the broad binding specificity that characterizes this unusual receptor. Scavenger receptors and C1q, along with the mannose-binding protein, conglutinin, and lung surfactant apoprotein A, help define a set of proteins which all contain short collagenous domains and which all appear to participate in host defense. Their short collagenous domains may contribute significantly to their host-defense functions.

Animals↗
PubMed1993

Patterns of central acetabular osteophytosis in osteoarthritis of the hip.

RATIONALE AND OBJECTIVES: The frequency and morphology of central acetabular osteophyte formation were evaluated in patients with osteoarthritis. METHODS: One hundred preserved acetabular specimens were evaluated for the occurrence of central osteophytes (excrescences present in the articulation of the hip joint), their relationship to marginal and femoral osteophytes of the hip, and their radiographic appearance. RESULTS: In both specimen and patient analysis, the authors found that central excrescences occur commonly and appear to be related temporally to osteophytes of the femur and the margin of the acetabulum. CONCLUSIONS: The authors demonstrated a close relationship between the degree of marginal and femoral osteophytes with those found centrally, indicating a temporal relationship. The new radiographic signs discussed are: 1) a fine linear density associated with early osteoarthritis; 2) larger, more irregular densities associated with a more advanced stage of osteoarthritis; and 3) obliteration of the acetabular fossa by excrescences as found in severe osteoarthritis.

Acetabulum↗
PubMed1993

Rapidly destructive hip disease: clinical and imaging abnormalities.

The clinical and radiographic records of 23 patients (15 women, eight men) with rapidly destructive hip disease (RDHD) were retrospectively reviewed. Criteria for RDHD included a history of hip pain of 1-6 months duration and the radiographic appearance of a rapidly progressive atrophic form of bone destruction involving both the femoral head and the acetabulum. Radiographs of the remainder of the appendicular skeleton were assessed in 14 patients. The mean patient age was 72 years. The average time from clinical presentation to the appearance of severe hip destruction was 14 months. Five patients demonstrated similar atrophic bone destruction around other articulations. No patients had clinical or laboratory evidence of sepsis or neurologic disease. Although previous reports have suggested that RDHD is degenerative in nature, similar involvement of other articulations suggests that it may represent a focal finding of a more generalized process.

Aged↗
PubMed1993

Abnormalities of articular cartilage in the knee: analysis of available MR techniques.

In an attempt to improve the detection of chondral abnormalities with magnetic resonance imaging, a fat-suppressed three-dimensional gradient-recalled acquisition in the steady state (GRASS) and spoiled GRASS (SPGR) sequence was optimized by study of five cadaveric knee specimens. Results with this optimized sequence then were compared with results with three spin-echo (T1-, proton-density-, and T2-weighted) and two three-dimensional gradient-recalled echo sequences (GRASS and non-fat-suppressed SPGR) in the assessment of naturally occurring abnormalities of the patellofemoral compartment in 10 cadaveric knees. Results with the optimized fat-suppressed SPGR sequence were significantly better (P < .02) than results with the other five sequences and had a sensitivity of 96%, a specificity of 95%, and an accuracy of 95%. In addition, normal cartilage consistently appeared as a trilaminar structure with the fat-suppressed SPGR sequence, a feature that appeared to help in identification of chondral lesions.

Aged↗
PubMed1993

Cervical spine: comparison of 45 degrees and 55 degrees anteroposterior oblique radiographic projections.

The orientation of the intervertebral foramina (IVF) at six cervical levels on transaxial images in 65 magnetic resonance (MR) studies was determined to explain variations in size and shape evident on the 45 degrees standard radiographic oblique view. Analysis of MR imaging data showed that substantial variations in the orientation of the cervical IVFs occurred throughout the cervical spine and that a 55 degrees anteroposterior (AP) oblique view with standard radiography probably would lead to better visualization of the lower cervical IVFs. These results were confirmed with a radiographic and anatomic study of two cadaveric specimens. In a prospective clinical study of 23 patients, 45 degrees and 55 degrees AP oblique views were compared by measuring the maximal transverse diameter of all the cervical IVFs. IVF size was substantially increased on the 55 degrees AP oblique projection at all lower cervical levels. The 55 degrees AP oblique view of the cervical spine is optimal for evaluating the lower cervical foramina and can be a routine alternative to the 45 degrees oblique view in the analysis of all cervical foramina.

Adult↗
PubMed1993

Gamekeeper thumb: differentiation of nondisplaced and displaced tears of the ulnar collateral ligament with MR imaging. Work in progress.

Ulnar collateral ligament (UCL) injury of the first metacarpophalangeal joint (gamekeeper thumb) is common. If the UCL becomes displaced superficially to the adductor pollicis aponeurosis, surgical treatment has been advocated. Radiography cannot help differentiate between displaced and nondisplaced tears. The authors investigated the use of magnetic resonance (MR) imaging in the evaluation of UCL injury. Ten displaced and six nondisplaced UCL tears were surgically created in 16 nonembalmed cadaveric specimens. Twelve unaltered specimens served as controls. Coronal MR images were obtained and interpreted by two observers. The MR images were compared with corresponding anatomic slices. MR imaging depicted UCL displacement in all 10 specimens with displaced tears. A displaced tear was interpreted in one control specimen. Non-displaced tears were diagnosed in four control specimens. Although MR imaging was only 67% specific for all tears, it was 100% sensitive and 94% specific for depicting UCL displacement and, therefore, may be useful for evaluating gamekeeper thumb.

Adult↗