William G. Negendank

Synovial thickening detected by MR imaging in osteoarthritis of the knee confirmed by biopsy as synovitis

Previous studies have established the value of magnetic resonance imaging (MRI) in detecting articular changes characteristic of osteoarthritis (OA) of the knee. We have observed some MRI features in OA of the knee presumably indicating synovial thickening. To determine whether these MR features represent chronic synovial inflammation, we studied the knees of nine patients at the mild end of the spectrum of OA of relatively short duration (89%: < or = 4 yr), who were selected because MRI showed anatomical abnormalities compatible with synovial thickening. The painful knee was examined using conventional and weight-bearing radiographs, MRI, and arthroscopy. MR images suggestive of synovial thickening typically appeared in or near the intercondylar region of the knee, in the infrapatellar fat pad, or in the posterior joint margin. The site of an arthroscopic biopsy of the synovial membrane was guided by MRI to the area thought to represent synovial thickening for each patient knee. Pathological examination of these synovial membrane biopsies showed a mild chronic synovitis, and thus a correspondence with the synovial thickening detected by MRI. Our results suggest that MRI can be used to evaluate the extent of synovitis, observed as synovial thickening, in patients with early OA of the knee.

MR features of osteoarthritis of the knee

A group of patients with idiopathic osteoarthritis (OA) of the knee was surveyed using weight-bearing radiographs and MR imaging to compare the relative value of these methods in disease evaluation. Fifty-two patients with a clinical and radiological diagnosis of OA of the knee of relatively short duration (87%: < or = 4 yr) were compared to a reference group of 40 age- and sex-comparable subjects with no knee symptoms. All patients had a complete history, physical examination, standard anterior-posterior and lateral weight-bearing radiographs, T1-weighted, and FLASH MR images in both knees. The prevalence of MRI abnormalities was significantly greater in patients with OA of the knee in all radiographic grades (Kellgren and Lawrence) compared to the reference subjects. Significant differences were encountered for synovial thickening (OA, 73%; reference, 0%), synovial fluid (60%; 7%), meniscal degeneration (52%; 7%), osteophytes (67%; 12%), and subchondral bone involvement (65%; 7%), even in the patients at the mild end of the osteoarthritic spectrum, indicating the exquisite sensitivity of MRI compared with weight-bearing radiographs.

Articular cartilage defects of the knee: correlation between magnetic resonance imaging and gross pathology.

Magnetic resonance imaging (MRI) of the knee articular cartilage is possible owing to the contrast provided by different signal intensities of adjacent menisci and subchondral bone. The objective of this study was to determine the accuracy of MRI in quantitatively detecting thinning and focal defects of articular cartilage in vivo. High resolution MRI was performed followed by dissection of the knee within one hour of amputations above the knee of eight patients (62-89 years) with peripheral vascular disease. Articular cartilage was examined for erosions, surface irregularities, and appearance. Mean thicknesses of femoral and tibial articular cartilage sagittal sections from MRI were statistically indistinguishable from matched gross thicknesses. In those joints in which cartilage erosions, thinning, or irregularities were detected by MRI the same defects were apparent by gross examination. Cartilage that appeared normal by MRI had a normal gross appearance by gross examination. Thus high resolution MRI can accurately predict gross articular cartilage appearance and thickness, allowing an objective, quantitative, noninvasive assessment of eroded cartilage.

Periorbital necrobiotic xanthogranuloma and stage I multiple myeloma. Ultrastructure and response to pulsed dexamethasone documented by magnetic resonance imaging.

We observed a 40-year-old woman with necrobiotic xanthogranuloma from the inception of indurated eyelid and periorbital infiltrates and concurrent stage I multiple myeloma to resolution of infiltrates in skin and bone marrow after pulsed high-dose oral dexamethasone therapy. Ultrastructural studies revealed lipid vacuoles in epidermal keratinocytes, in dermal histiocytic macrophages, and in vascular and lymphatic endothelial cells. The presence of lipid vacuoles in epidermal keratinocytes has not been reported previously in xanthogranuloma.

Occult tibial fracture in a gymnast: Diagnosis by magnetic resonance imaging A case report

Magnetic resonance imaging (MRI) is becoming an important tool in the diagnosis of musculoskeletal injury. This technique is most useful in the evaluation of soft tissue, since it provides excellent contrast between structures and has also been effectively used in the detection of intraarticular trauma.’ In general, MRI is believed to be inferior to standard radiography or computed tomography (CT) in the evaluation of fractures.’ We recently treated a patient in which the MRI scan identified a fracture not visualized on plain radiographs or CT scan. We present this case to report our finding and to suggest the use of MRI in cases where diagnosis is unclear and plain radiographs fail to detect any abnormality.

Bladder Lymphoma: Diagnosis and Documentation of Response by Magnetic Resonance Imaging

Invasion of the bladder by lymphoma rarely is encountered clinically. The characteristics on magnetic resonance imaging have not been described. We report a case of secondary nonHodgkins lymphoma of the bladder in which we show the ability of magnetic resonance imaging to visualize the lymphomatous invasion and to monitor the response to chemotherapy.

A cooperative transition theory applied to the kinetics of ionic exchanges in cells

Manifestations of a cooperative interaction between ion-adsorbing sites in cells include steep, sigmoidal equilibrium adsorption isotherms of K+ and Na+, critical temperature transitions of net exchanges of Na+ for K+, and the allosteric nature of the effects of ligands on cellular K+ and Na+. Cooperative ionic adsorption is described by a onedimensional Ising model. The experimentally-determined equilibrium parameters permit prediction of the kinetics of exchange of K+ for Na+ (the approach to equilibrium) by stochastic or hydrodynamic solutions of a time-dependent Ising model. Studies of the rates of self-exchange of adsorbed ions reveal properties of the cooperatively interacting adsorption sites and their dependence on temperature and chemical potential. High rates of isotopic exchanges of K+ and Na+ occur near the transition point. This is explained by the hypothesis of an increase in susceptibility of the ensemble to slight variations of {ie93-1} or {ie93-2} near the phase transition, which leads to an increase in microscopic fluctuations within the ensemble. It is suggested that the isotopic ionic exchange experiment may be a means to explore the microscopic states of the ensemble and their transition probabilities.