Biomedical subjects
Publications and source records attributed to G Sze.
We report a case of Guillain-Barré syndrome with enhancement of multiple cranial nerves seen with postcontrast MR imaging. Clinical symptoms and electrodiagnostic studies reflected abnormalities of some but not all of the enhancing cranial nerves.
Two cases of neurocutaneous melanosis are presented. MR showed hyperintense areas in the brain on short-repetition-time/short-echo-time sequences, compatible with intraparenchymal melanin deposits. No leptomeningeal abnormality was seen.
PURPOSE: To compare conspicuousness of head and neck lesions on fast spin-echo sequences and conventional spin-echo sequences. METHODS: Forty consecutive patients with 61 head and neck lesions were evaluated. Lesion conspicuousness was qualitatively compared on conventional spin-echo and fast spin-echo sequences, using both spin-density and T2-weighted images. Thirty-six lesions had surgical or pathologic confirmation, and 25 were assigned a presumptive diagnosis based on clinical evaluation and imaging findings seen on conventional spin-echo T1- and T2-weighted sequences. Forty lesions were related to neoplasms; 21 lesions consisted of infectious, vascular, or inflammatory abnormalities. RESULTS: Fast spin-echo sequences provided improved lesion conspicuousness in 91% of spin-density images, in 77% of T2-weighted images, and in 84% of the combined spin-density and T2-weighted images. CONCLUSION: By providing shorter imaging times and equal or superior lesion conspicuousness, long-repetition-time fast spin-echo sequences can replace long-repetition-time conventional spin-echo sequences in evaluation of the head and neck.
PURPOSE: To determine whether the method of delivery of gadolinium can alter optimal small-vessel detail in MR angiography. METHODS: Six healthy volunteers were studied with MR angiography using both a constant infusion and a bolus method of contrast administration to a total dose of 0.1 mmol/kg. Both three-dimensional time-of-flight and 3-D phase-contrast techniques were used. RESULTS: Constant infusion did not prove superior to bolus administration of contrast. With both techniques, gadolinium enhancement uniformly improved visualization of small vessels. Delay from the time of contrast administration to scan acquisition decreased vessel enhancement. CONCLUSIONS: Bolus administration of gadolinium is sufficient to improve small vessel visualization with MR angiography. When a series of contrast-enhanced images is to be obtained, MR angiographic sequences should be obtained first.
We present MR imaging findings of a 15-year-old girl with a history of chronic back pain, proved by biopsy to be caused by primary extraosseous Ewing sarcoma, extending into the spinal epidural space. We also demonstrate the involvement of the adjacent structures and encroachment on the intervertebral foramina.
To investigate the safety and efficacy of the low-osmolar, nonionic contrast agent, gadodiamide injection (Omniscan, Sanofi Winthrop Pharmaceuticals, New York, NY), for magnetic resonance imaging (MRI) of the head and spine, a multicenter study involving 439 patients was done at 15 centers as part of a Phase II/III clinical trial. Unenhanced MRI scans were obtained after which the patients were injected with 0.1 mmol/kg gadodiamide, and the MRI was repeated. The patients' vital signs were monitored, and laboratory studies were conducted. Neurologic status was examined before and after the study. The images were evaluated for contrast enhancement. No patient had any significant adverse event or serious change in clinical status. Abnormalities were found in 80% (351) of all patients studied, and it was found that, in 75% (266) of these, the postgadodiamide injection images were improved or facilitated visualization of lesions compared with preinjection images. The investigators believe that, based on the results of this study, gadodiamide injection is safe and effective for imaging the head and spine. They suggest that future studies further assess and compare the safety parameters of gadodiamide injection with those of other nonionic and ionic gadolinium ligands.
To compare the efficacies of fast spin-echo (FSE) and inversion-recovery FSE (IRFSE) magnetic resonance (MR) imaging in evaluating head and neck disorders, the authors evaluated 46 lesions in 23 consecutive patients. Twenty-seven lesions were related to neoplasms; 19 lesions resulted from infectious, allergic, or radiation-induced inflammation. Conventional T1-weighted, FSE, and IRFSE images were obtained in all patients. The FSE and IRFSE images were qualitatively compared in an unblinded manner for conspicuity of lesion margins and extent. IRFSE imaging improved conspicuity of 22 lesions (48%) and showed equal conspicuity of 18 (39%). IRFSE imaging proved most useful for small lesions with long T2 relaxation times that were surrounded by fat. IRFSE imaging improved visibility of small optic nerve gliomas, salivary gland inflammation, peripheral nerve tumors, and small lymph nodes. Early changes secondary to spread of tumor across fascial planes were also well visualized with IRFSE sequences. In six lesions (13%) that did not have long T2 relaxation times, the FSE images provided better conspicuity. The authors conclude that by improving conspicuity of small lesions adjacent to or surrounded by fat, IRFSE sequences can supplement FSE sequences in imaging the head and neck.
Rat hepatocytes exhibit bidirectional carrier-mediated transport of reduced glutathione (GSH) across the plasma membrane. Transport of GSH has not been well characterized in human-derived cells. We examined Hep G2 cells as a possible human liver model for GSH homeostasis. Hep G2 cell GSH averaged 25.9 +/- 1.4 nmol/10(6) cells. When Hep G2 cells were incubated in buffer, no GSH appeared in the medium over 2 h. However, after pretreatment with acivicin to inhibit gamma-glutamyl transpeptidase activity, GSH efflux was unmasked and measured 30 +/- 4 pmol x 10(6) cells-1 x min-1, which is comparable to rat hepatocytes. GSH efflux was inhibited by sulfobromophthalein GSH adduct (BSP-GSH) and cystathionine, agents that inhibit sinusoidal efflux in the rat, and was stimulated by adenosine 3',5'-cyclic monophosphate-dependent agents. GSH uptake was measured after cells were pretreated with acivicin and buthionine sulfoximine to prevent breakdown of GSH and resynthesis of GSH from precursors, respectively. In the presence of 4 microCi/ml of [35S]GSH and 10 mM unlabeled GSH, GSH uptake was linear up to 45 min and did not require Na+ or Cl-. GSH uptake exhibited saturability with a maximal velocity of 4.15 +/- 0.23 nmol.mg-1 x 30 min-1, a Michaelis constant of 2.36 +/- 0.26 mM, and two interactive transport sites. BSP-GSH cis-inhibited GSH uptake in a dose-dependent manner with an inhibitory constant of 0.46 +/- 0.05 mM. Inhibition by BSP-GSH (1 mM) of GSH uptake was through a single inhibitor site and was overcome at > 10 mM GSH, which is consistent with competitive inhibition. Similar to the rat, 10 mM extracellular GSH trans-stimulated GSH efflux. These findings may be important in gaining better insights into GSH homeostasis in human liver cells.
Although the meninges are often thought of simplistically as a connective tissue sac that contains the CSF and the contents of the CNS, they are far more complex. Anatomically, they comprise several layers. Pathologically, numerous disease processes may affect the meninges; different processes may even involve different areas of the meninges. These factors all influence the MR imaging characteristics of meningeal lesions. This review briefly discusses the anatomy of the meninges, the MR imaging technique when meningeal disease is suspected, and the appearance of the normal meninges. It then focuses on tumors, infections, cysts, and other lesions that primarily involve the meninges, excluding lesions that secondarily involve the meninges.
The application of magnetic resonance imaging has changed the evaluation of most disorders of the spinal axis. Contrast agents improve lesion conspicuousness and new sequences decrease both imaging time and artifacts. Myelography, computed tomography, and angiography continue to have well-defined, albeit limited, roles in spinal imaging.
The advent of MR imaging has dramatically altered the evaluation of suspected myelopathy. MR is far less invasive than traditional imaging techniques and often offers a degree of understanding of an abnormality not previously possible. These achievements have closely followed recent technologic advances, such as the development of contrast agents and the introduction of sequences that permit a reduction in both imaging time and artifacts. The current role of MR in the imaging of spinal cord disorders, including intramedullary tumors, infectious and inflammatory myelitis, demyelinating diseases, vascular lesions, trauma, syringomyelia/hydromyelia, and neurodegenerative disorders, is reviewed. While further improvements will undoubtedly occur, the field of spinal MR imaging appears to be entering a maturing phase.
In recent years, one of the most common reasons for neuroimaging has become the evaluation of the immunosuppressed patient. In this review the radiographic appearances of the common inflammatory and neoplastic conditions affecting the central nervous system in patients with HIV infection, as well as the AIDS-dementia complex, are discussed. Non-AIDS immunocompromised neurologic disease is also examined, with particular emphasis on the effect of various immunosuppressive medications on the brain and spine.
Magnetic resonance imaging (MRI), which has recently begun to replace myelography, postmyelography computed tomography (CT), and to some extent, bone scans, has become the procedure of choice in the evaluation of spinal tumors; the applications of MRI in this role are reviewed. In the extradural space, MRI is the most sensitive technique for the detection of tumors in the vertebral bodies. At the same time, it provides superb delineation of suspected thecal sac impingement. In the intradural extramedullary space, MRI is generally as accurate as myelography and postmyelography CT while being noninvasive. Finally, in the intramedullary space, MRI is unquestionably the procedure of choice in the evaluation of suspected cord tumors. In general, MRI has become the best initial procedure in the evaluation of suspected tumors of the spine, regardless of the space in which they may lie; frequently, it is the only required examination.
Explore the source record for details and available documents.
Syphilitic meningitis, which can occur near the time of secondary syphilis, is frequently asymptomatic. There has been one recent report of an HIV-positive patient who developed syphilitic polyradiculopathy following a recent history of secondary syphilis. We describe an HIV-negative woman in whom paraparesis occurred secondary to syphilitic meningitis. Complete recovery followed a course of high-dose intravenous penicillin therapy, emphasizing the treatable nature of this cause of paraparesis.
Minimal to mild enhancement of skeletal muscles is normally seen on gadolinium-enhanced magnetic resonance images. The enhancement of the extraocular muscles is much more intense than that of other skeletal muscles. The authors investigated the structural features of extraocular muscles that contribute to this increased enhancement. After comparing samples of extraocular muscle and quadriceps muscle, the authors concluded that the rich vascularity and the prominence of extravascular space most probably cause extraocular muscles to demonstrate intense enhancement on gadolinium-enhanced images.
Enhancement characteristics of the normally developing spinal column were examined in magnetic resonance (MR) images obtained in 58 children aged 7 days to 9 years. With a 1.5-T imager, short-repetition-time spin-echo images were obtained before and after the administration of 0.1 mmol/kg gadopentetate dimeglumine. Enhancement of normal bone marrow was seen in all patients aged less than 7 years; it was marked only in patients aged less than 2 years. Enhancement of normal cartilage, seen in all patients aged less than 1 1/2 years, may be the most striking feature of enhanced MR images of the infant spine. Enhancement of both bone marrow and cartilage in children appears to be due to the unusual prominence of vasculature, associated with permeability of the capillary endothelium and a plentiful extravascular space. Although marked and diffuse enhancement of vertebral bodies in adults is often thought to indicate a pathologic marrow state, caution must be used before the same criteria are applied to children.
To evaluate the safety and efficacy of gadodiamide injection, a nonionic gadolinium chelate complex, in magnetic resonance (MR) imaging of the head and spine, a phase II-III trial was conducted in 439 patients with known or suspected lesions in the central nervous system. All patients received gadodiamide injection in a dosage of 0.1 mmol/kg and were monitored; MR images were evaluated for contrast material enhancement. No serious adverse events or clinically important trends in vital signs, laboratory values, or neurologic status were observed. Gadodiamide injection enhanced or facilitated the visualization of lesions in 266 or 353 patients (75.4%) in whom lesions were shown on unenhanced images, enhanced images, or both; in these 266 patients, the diagnosis was changed in 76 patients (28.6%) and facilitated in 190 patients (71.4%). It is concluded that gadodiamide injection is safe and effective for MR imaging of the head and spine in patients with suspected abnormalities of the central nervous system.