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G Sze

Publications and source records attributed to G Sze.

At least 19 recordsLinked to original sources
PubMed2001

Magnetic resonance imaging of spinal cord vascular malformations with an emphasis on the cervical spine.

Spinal vascular malformations (AVMs) are rare but important causes of treatable myelopathies. Recent advances in the interventional neuroradiology and neurosurgical techniques have improved the delineation and classification of these heterogeneous lesions. Because MR imaging usually is the first screening test for patients with myelopathy, the neuroradiologist must have a high level of knowledge of the common imaging characteristics of these lesions. This article reviews MR angiographic literature about spinal AVMs, Type I-IV AVMs and cervical Type I AVMs, describes their pathophysiology and common imaging characteristics, and elaborates on differences in cervical location from more typical positions.

Arteries↗
PubMed2000

Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA).

RATIONALE AND OBJECTIVES: The objective of the two pivotal phase 3 studies was to evaluate the safety and efficacy of OptiMARK (Gd-DTPA-bis(methoxyethylamide) [Gd-DTPA-BMEA]) compared with Magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system. METHODS: Two multicenter, randomized, double-blind, parallel group studies were conducted in 395 patients with known or suspected central nervous system pathology. Subjects were randomized to receive a single 0.1 mmol/kg intravenous injection of either Gd-DTPA-BMEA or Gd-DTPA. The safety of Gd-DTPA-BMEA and Gd-DTPA was monitored for up to 72 hours after study drug administration. Precontrast and postcontrast administration magnetic resonance scans were acquired using identical imaging planes and techniques. RESULTS: No deaths or unexpected adverse events were reported in either group. A comparison of adverse events by intensity and relation demonstrated no statistically significant differences between the two groups. Gd-DTPA-BMEA and Gd-DTPA were equivalent with respect to confidence in diagnosis, conspicuity, and border delineation. CONCLUSIONS: Gd-DTPA-BMEA and Gd-DTPA demonstrated comparable efficacy profiles, and the safety profiles were considered similar.

Adult↗
PubMed2000

The potential for vigabatrin-induced intramyelinic edema in humans.

PURPOSE: Vigabatrin (Sabril, Hoechst Marion Roussel) is an antiepilepsy drug (AED) presently marketed in 64 countries for the treatment of partial and secondarily generalized seizures. Vigabatrin (VGB) is marketed in a subset of these countries for the treatment of infantile spasms. Clinical experience in humans has shown that VGB provides effective seizure control with a wide margin of safety. However, animal toxicity studies raised concern when prolonged administration of VGB was shown to induce intramyelinic edema (IME) in some laboratory animal species. METHODS: Animal and human data were reviewed with respect to the potential for VGB-induced IME. Surveillance of patients receiving VGB in clinical trials or by prescription has been conducted for >15 years to identify patients developing clinical abnormalities that might be IME related. RESULTS: The histologic lesions of VGB-induced IME in animals are reliably reproduced and correlate with changes in multimodality evoked potentials (EPs) and magnetic resonance imaging (MRI). Numerous studies of the effects of VGB on EP and MRI in epilepsy patients have demonstrated no clear-cut IME-related changes in these modalities. Additionally, autopsy and surgical brain samples from VGB-treated patients have been scrutinized for potential IME histopathology. In an estimated 350,000 patient-years of VGB exposure (approximately 175,000 patients exposed for 2 years at an average dose of 2 g/day), no definite case of VGB-induced IME has been identified. CONCLUSIONS: Comprehensive review of a variety of sources of data failed to identify any definite case of IME in humans treated with VGB.

Animals↗
PubMed2000

Parenchymal perianeurysmal cystic changes in the brain: report of five cases.

PURPOSE: To describe parenchymal perianeurysmal cystic changes in the brain. MATERIALS AND METHODS: Among 247 patients with cerebral aneurysms described in the medical or radiologic records in three institutions, five had perianeurysmal cystic changes. These were evaluated with computed tomography or magnetic resonance (MR) imaging and were categorized according to size, appearance, and the presence of hemosiderin deposit. Confirmation at stereotactic needle biopsy was available in one case. RESULTS: Perianeurysmal cysts comprised multiple clustered cysts in three cases and a unilocular cyst in two, and diameters were 1.5-3.5 cm. Hemosiderin was depicted at MR imaging in one unilocular cyst. Associated aneurysms had diameters of 0.7-4.0 cm, and prominent aneurysmal thrombosis and calcifications were seen in two cases. Findings at stereotactic needle biopsy were of mild reactive gliosis. At long-term follow-up in two patients, the cystic regions were stable. CONCLUSION: Parenchymal perianeurysmal cysts are rare and may display various morphologic characteristics from unilocular to multilocular. Since there may or may not be evidence of previous hemorrhage, other mechanisms such as abnormal angiogenesis factors may play a role.

Adult↗
PubMed2000

Choroid plexus changes after temporal lobectomy.

BACKGROUND AND PURPOSE: Postoperative contrast-enhanced MR imaging of the brain is routinely used when evaluating for residual or recurrent brain tumor. It is imperative to be aware of morphologic changes and imaging features that typically occur in response to surgical manipulation at the postoperative site to avoid misinterpretation of imaging findings. Our purpose was to determine normal postoperative changes and alterations in the choroid plexus among patients who had undergone temporal lobectomy in order to distinguish this appearance from pathologic changes that may be seen in the presence of infection or recurrent tumors. METHODS: We reviewed 159 MR scans from 95 patients with hippocampal sclerosis or gliosis who underwent temporal lobectomy for treatment of intractable epilepsy. Choroid plexus location and size were assessed on contrast-enhanced T1-weighted images. RESULTS: After temporal lobectomy, the choroid plexus enlarged and sagged into the resection site. Increase in the size of the choroid plexus occurred in 58% of cases overall. The degree of enhancement also increased after surgery, sometimes resulting in a nodular pattern of enhancement. The changes were most marked during the 1st week after temporal lobectomy, and showed an enlarged, markedly enhancing choroid plexus on 86% of the scans. CONCLUSION: Postoperative changes of the choroid plexus after temporal lobectomy include sagging into the resection site, an increased size, and an increased degree of enhancement. Normal postoperative morphologic characteristics may mimic neoplastic enhancement pattern. Familiarity with this appearance is important to avoid a pitfall in diagnosis of recurrent postoperative temporal lobe neoplasms.

Adolescent↗
PubMed1998

Stroke in a neonate heterozygous for factor V Leiden.

Activated protein C resistance is the most common hereditary coagulation abnormality and is caused by the factor V Leiden mutation. A newborn who developed seizures within hours after delivery and was found to have a bihemispheric stroke is described. This patient, determined to be heterozygous for factor V Leiden, is the first reported case of neonatal stroke associated with this common mutation.

Cerebrovascular Disorders↗
PubMed1998

Regression of HIV encephalopathy and basal ganglia signal intensity abnormality at MR imaging in patients with AIDS after the initiation of protease inhibitor therapy.

PURPOSE: To determine whether protease inhibitors cause regression of periventricular white matter signal intensity abnormalities in patients with human immunodeficiency virus (HIV) encephalopathy and whether the changes on magnetic resonance (MR) images correlate with cognitive improvement. MATERIALS AND METHODS: MR images were retrospectively and prospectively analyzed in 16 adult patients with HIV encephalopathy. White matter and basal ganglia signal intensity abnormalities on initial long repetition time (TR) images were compared with those on subsequent long TR images in patients who received and in patients who did not receive protease inhibitors. Clinical correlation was obtained. RESULTS: Of the nine patients receiving protease inhibitors, four showed nearly complete regression, four showed interval stability, and one showed slight progression. Thus, eight patients (89%) demonstrated either stability or improvement in white matter disease, which correlated with cognitive improvement. Of the seven patients not receiving protease inhibitors, six (86%) showed marked progression with a decline in cognitive function and one had no interval change. The difference between the two groups was statistically significant. Of the two patients receiving protease inhibitors who initially had basal ganglia signal intensity abnormalities, one demonstrated resolution and one nearly complete resolution subsequently. CONCLUSION: Although the patient population is small, protease inhibitors may cause regression of periventricular white matter and basal ganglia signal intensity abnormalities in HIV encephalopathy and may have a role in treatment.

AIDS Dementia Complex↗
PubMed1998

Small, patent cerebral aneurysms: atypical appearances at 1.5-T MR imaging.

PURPOSE: To determine the frequency and characteristics of small cerebral aneurysms with atypical appearances on magnetic resonance (MR) images. MATERIALS AND METHODS: MR imaging studies (n = 117) obtained at 1.5 T of small aneurysms (< 1 cm diameter) were prospectively and retrospectively analyzed. Signal intensity characteristics and gadolinium-enhancement patterns in 84 aneurysms (62 patients) were evaluated. The patency of all aneurysms was confirmed at angiography or at the time of surgery. RESULTS: A characteristic signal void was seen on 62 (53%) of 117 studies. On the remaining 55 (47%) studies, aneurysms had atypical signal intensity that was isointense, heterogeneous, or hyperintense. Contrast-enhanced aneurysms were seen on 27 (53%) of 51 gadolinium-enhanced studies. CONCLUSION: Atypical MR imaging characteristics were seen in roughly half of cases. These atypical-appearing aneurysms may erroneously be considered to be thrombosed or be mistaken for other common lesions such as small tumors and be dismissed as nonvascular.

Adolescent↗
PubMed1998

Hypophysitis: endocrinologic and dynamic MR findings.

PURPOSE: Our purpose was to assess the worth of dynamic MR imaging in the evaluation of vascular changes of the pituitary in patients with lymphocytic hypophysitis. METHODS: Five patients (four males, one female; 9 to 53 years old) with lymphocytic hypophysitis or infundibuloneurohypophysitis were studied. All patients underwent endocrinologic studies and a series of two to five MR examinations performed over a period of 8 months to 5 years, including a total of nine dynamic imaging studies. RESULTS: Two patients had panhypopituitarism and three had partial hypopituitarism. Diabetes insipidus was present in four patients. Among the five patients, the pituitary was enlarged in three, of whom two showed improvement on follow-up MR studies. Three patients had a thickened stalk, which improved on subsequent examinations. In all nine dynamic studies, the enhancement time of the whole pituitary was delayed to over 90 seconds, even though five of the nine conventional, simultaneously performed MR studies showed a normal pituitary. The peak time of posterior pituitary enhancement in the first dynamic study was also delayed in all patients (from 60 to 120 seconds). In two patients, normal early enhancement of the posterior pituitary was identified on initial studies but not on subsequent studies. CONCLUSION: Dynamic MR imaging can display an abnormality of the hypophysial vasculature even if the pituitary disease is seen to regress on the conventional MR study. The delay or even the lack of early enhancement of the posterior pituitary in lymphocytic hypophysitis may be due to secondary inflammatory changes.

Adolescent↗
PubMed1998

Comparison of single- and triple-dose contrast material in the MR screening of brain metastases.

PURPOSE: Although studies obtained with triple-dose contrast administration can show more brain metastases than those obtained with single-dose contrast material in patients with multiple metastases, such studies are costly and of limited clinical benefit. Since most patients who undergo screening have negative findings or a single metastasis, this study was performed to compare the clinical utility of single-dose versus triple-dose contrast administration in this large group of patients who could benefit from the possible increased sensitivity in lesion detection. METHODS: Ninety-two consecutive patients with negative or equivocal findings or a solitary metastasis on single-dose contrast-enhanced MR images underwent triple-dose studies. Findings were compared with a standard of reference composed of panel review and long-term follow-up. Further analysis was performed by comparing results with those obtained by two blinded readers. RESULTS: In all 70 negative single-dose studies, the triple-dose studies depicted no additional metastases in terms of the standard of reference. No statistically significant difference was seen between the results of the single- and triple-dose studies. For 10 equivocal single-dose studies, the triple-dose study helped clarify the presence or absence of metastases in 50% of the cases. In 12 patients with a solitary metastasis seen on the single-dose study, the triple-dose study depicted additional metastases in 25% of the cases. In the results of one of the two blinded readers, use of triple-dose contrast led to a statistical difference by decreasing the number of equivocal readings but at the expense of increasing the number of false-positive readings. CONCLUSION: Routine triple-dose contrast administration in all cases of suspected brain metastasis is not helpful. On the basis of our investigation, we conclude that the use of triple-dose contrast material is beneficial in selected cases with equivocal findings or solitary metastasis, although with the disadvantage of increasing the number of false-positive results.

Brain↗
PubMed1998

Colonic stents in colorectal obstruction.

Obstruction is the presenting symptom of colorectal cancer in up to 40 per cent of patients. Benign strictures and other neoplasms including lymphoma and gynecologic tumors occur as well. Emergent operative therapy is often suboptimal and associated with significant morbidity and mortality. Our objective was to review our experience with stent placement for colonic obstruction. Seven patients underwent stent placement for a total of eight procedures. There were three patients with unresectable colorectal cancer, two patients with metastatic gynecologic cancer, one patient with rectal lymphoma, and one patient with metastatic cancer of unknown primary. All colonic stents were Wallstents placed by the same endoscopist under fluoroscopic and endoscopic guidance. Stents were successfully placed in all patients without complication. One patient underwent placement of two stents in succession for a long stenosis. Six of seven patients (86%) had resolution of the obstruction and return of bowel function. Five of seven were tolerating a diet within 24 hours. One patient's mental status did not allow for oral intake. Four patients were discharged within 48 hours. Two patients died within the same hospitalization as a result of metastatic disease. One patient was found to have multilevel disease requiring stoma placement. There was no morbidity or mortality associated with stent placement, and 86 per cent of patients had palliation of the obstruction. We conclude that colonic stent placement is a safe and effective therapy for colorectal obstruction at this institution.

Colorectal Neoplasms↗
PubMed1997

Extradural spinal meningioma: MRI.

We report a case of extradural spinal meningioma with pathologically proven features of malignant transformation. The MRI findings of extradural spinal meningioma and differences in the findings from intradural meningiomas are discussed.

Adult↗
PubMed1997

Pituitary gland enlargement secondary to dural arteriovenous fistula in the cavernous sinus: appearance at MR imaging.

PURPOSE: To evaluate pituitary gland size in cases of dural arteriovenous (AV) fistula in the cavernous sinus and to correlate the size with the degree of AV fistula. MATERIALS AND METHODS: Magnetic resonance images in 21 patients with angiographically proved dural AV fistula of the cavernous sinus were retrospectively reviewed. In four patients, findings obtained before and after embolization therapy were compared. RESULTS: The 21 patients were divided into group 1 (severe AV fistula) and group 2 (moderate or mild AV fistula). The superior contour of the pituitary gland was convex or flat in group 1 and flat or concave in group 2. The mean height of the pituitary gland was 9.4 mm +/- 1.5 (standard deviation) in group 1 and 6.7 mm +/- 1.2 in group 2 (P = .0002). After embolization therapy, pituitary gland height decreased and signal intensity voids improved in the four patients and no AV fistula was observed in three. CONCLUSION: In cases of severe dural AV fistula in the cavernous sinus, the pituitary gland is enlarged, which should not be misdiagnosed as pathologic.

Adult↗
PubMed1997

Postoperative changes in the brain: MR imaging findings in patients without neoplasms.

PURPOSE: To determine the time course of postoperative changes in the brain by using magnetic resonance (MR) imaging. MATERIALS AND METHODS: Contrast material-enhanced MR images (32 preoperative, 161 postoperative) in 95 patients who underwent temporal lobectomy for treatment of nonneoplastic epilepsy were evaluated for enhancement pattern at the surgical margin and for the presence of dural enhancement, fluid, and air. Images were obtained 9 hours to 5.6 years after surgery. RESULTS: Surgical margin contrast enhancement was present and increased from 20 hours to 29 days after surgery. The predominant early (days 0-5) pattern was thin linear enhancement (16 of 18 [89%] images). The later (days 6-29) pattern was thick linear or nodular (tumorlike appearance) (11 of 18 [61%] images). Surgical margin enhancement was absent after day 30, although few data were collected 1-5 months after surgery. Dural enhancement was seen on 96 of 97 (99%) postoperative MR images. Extraaxial fluid was seen on all 46 images obtained during the first 30 days and was absent by day 51. Intracranial air was present on 31 of 35 (89%) images obtained during the first 4 days but was absent after day 5. CONCLUSION: Knowledge of the evolution of contrast enhancement patterns on postoperative MR images of the brain can help in differentiating benign from neoplastic changes.

Adolescent↗
PubMed1996

Role of two recently cloned rat liver GSH transporters in the ubiquitous transport of GSH in mammalian cells.

Recently our laboratory has cloned both the rat canalicular and sinusoidal GSH transporters (RcGshT and RsGshT, respectively; Yi, J., S. Lu, J. Fernandez-Checa, and N. Kaplowitz. 1994. J. Clin. Invest. 93:1841-1845; and 1995. Proc. Natl. Acad. Sci. USA. 92:1495-1499). The current work characterized GSH transport and the expression of these two GSH transporters in various mammalian cell lines. The average cell GSH levels (nmol/10(6) cells) were 25, 22, 32, 13, and 13 in HepG2, HeLa, CaCo-2, MDCK, and Cos-1 cells, respectively. GSH efflux was temperature dependent and averaged 0.018, 0.018, 0.012, 0.007, and 0.019 nmol/10(6) cells/min from HepG2, HeLa, CaCo-2, MDCK, and Cos-1 cells, respectively. Dithiothreitol (DTT), which stimulates rat sinusoidal GSH efflux, stimulated GSH efflux only in HepG2 and HeLa cells which was partially reversed by subsequent cystine treatment. GSH uptake (1 mM plus 35S-GSH) was temperature dependent, linear up to 45 min, and Na+-independent with average rates of 1.12, 0.91, 0.45, and 0.45 nmol/10(6) cells/30 min for HepG2, HeLa, CaCo-2, MDCK, and Cos-1 cells, respectively. BSP-GSH (2mM), which cis-inhibits sinusoidal GSH uptake in rat liver and HepG2 cells, inhibited GSH uptake only in HeLa cells. mRNA and polypeptide of RcGshT are expressed in all cells whereas those of RsGshT are expressed only in HepG2 and HeLa cells. In conclusion, bidirectional GSH transport, mediated by the "canalicular" GSH transporter, is ubiquitous in mammalian cells. Sinusoidal GSH transporter expression is more restricted, being present in HepG2 and HeLa cells. DTT and BSP-GSH affect GSH transport only in cells expressing the sinusoidal transporter confirming their selective action on this transporter.

Animals↗
PubMed1996

Nerve root hypertrophy as the cause of lumbar stenosis in chronic inflammatory demyelinating polyradiculoneuropathy.

Two patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) developed signs of lumbar stenosis. Radiologic, intraoperative, and pathologic findings demonstrated lumbar stenosis secondary to nerve root hypertrophy. This syndrome has been demonstrated in hereditary but not acquired demyelinating neuropathies. CIDP should be considered in the differential diagnosis of sciatica and nerve root hypertrophy.

Adult↗