Search PubMed⌕ Search

Biomedical subjects

G Sze

Publications and source records attributed to G Sze.

At least 55 records · Page 3Linked to original sources
PubMed1991

Evolution of the infant spinal column: evaluation with MR imaging.

The appearance of the normal lumbar spinal column was examined in spinal magnetic resonance images obtained in 50 pediatric patients aged 2 years or less. The ossification centers of the developing vertebral bodies, the cartilage, and the disks were studied with a 1.5-T imager by using both short- and long-repetition-time spin-echo sequences. Many of the structures of the spine were noted to undergo dynamic changes in appearance, both in signal intensity and in morphologic characteristics, with growth. The vertebrae and cartilage, especially, transform markedly in infancy and proceed through three characteristic stages of evolution. Stage I, from birth to 1 month of age, is characterized by markedly hypointense ossification centers and hyperintense, prominent cartilage. Stage II, from approximately 1 to 6 months of age, is characterized by increasing signal intensity in the ossification centers, progressing from the endplates in, and decreasing prominence of the cartilage, Stage III, from approximately 7 months of age on, is characterized by increasingly rectangular and centrally intense vertebral bodies and diminishing cartilage. The variability of the signal intensities, with that of muscle used as the standard, and morphologic characteristics of different components of the spine at different stages of development can create significant confusion. Careful analysis, however, permits one to follow the evolution of the lumbar spine and to date it on the basis of its appearance.

Cartilage↗
PubMed1991

Magnetic resonance imaging of spinal infection.

The findings on magnetic resonance imaging in various types of spinal infection are described, including disc space infection and osteomyelitis, epidural abscess, paraspinal abscesses, and meningitis. The characteristic appearance of spinal infection on both plain and gadolinium-enhanced magnetic resonance is contrasted with that of the normal spine.

Abscess↗
PubMed1991

Recent advances in spinal magnetic resonance imaging.

The application of recent technologic innovations, such as phase-array coil technology, saturation bands in the field of view, variable bandwidth, new methods of image display, new applications of contrast agents and ultrafast spin-echo imaging, promises to improve even further the scope and versatility of magnetic resonance imaging of the spine. Several of the new methods, such as the fat-saturation and variable-bandwidth techniques, have been applied to imaging the head, but their use in imaging the spine has lagged for various technologic reasons. For other advances, such as phased-array coil technology, minor problems, including prolonged reconstruction time, have yet to be overcome. Still others, such as ultrafast spin-echo imaging, have been developed so recently that they have just begun to enter clinical trials. All of these techniques promise to improve the quality and, in some cases, the speed of spinal magnetic resonance imaging and should allow an even better understanding of the anatomy and pathology of the spine.

Aged↗
PubMed1990

Decompression of epidural metastases from germ cell tumors with chemotherapy.

Epidural cord compression from germ cell tumor metastases is not common. Treatment usually requires high dose corticosteroids with radiation therapy and/or surgical decompression. Three patients with epidural germ cell tumor metastases were treated with cisplatin-based chemotherapy and all three had complete neurologic recovery. Systemic chemotherapy should be considered as initial therapy with corticosteroids for epidural cord compression from metastatic germ cell tumor.

Adult↗
PubMed1990

New applications of MR contrast agents in neuroradiology.

Contrast enhancement has now become an integral part of MR imaging. In this paper, the current uses of contrast agents in MR imaging of both the head and spine are reviewed. In addition, new applications of contrast in MR imaging, including some more current and controversial, are also explored.

Bone Diseases↗
PubMed1990

Emotional facial paresis with striatocapsular infarction.

Emotional facial paresis (EFP) refers to hemifacial paresis of emotionally evoked or spontaneous smiling or weeping with preserved volitional movements of the face. The anatomical location for this phenomenon has been controversial. We report a 15-year-old boy with EFP. Follow-up MRI demonstrated infarction limited to the head of the caudate, putamen and anterior limb of the internal capsule on the contralateral side. This case lends support for selective damage at a striatal or capsular site in the production of EFP.

Adolescent↗
PubMed1990

Calvarial and skull base metastases: comparison of nonenhanced and Gd-DTPA-enhanced MR images.

Fourteen patients with calvarial metastases were studied with magnetic resonance (MR) imaging before and after intravenous administration of gadolinium diethylenetriamine-pentaacetic acid (DTPA) to evaluate the utility of contrast material enhancement for the detection of calvarial metastatic tumor. MR imaging was also performed before and after enhancement in 60 patients for reasons other than evaluation of metastases or calvarial tumor, to determine the apperance of the normal calvaria with enhancement. The normal pattern of fat distribution in the diploic space was typically symmetric. Except for enhancement of diploic veins and meninges near pacchionian granulations, the normal diploic space did not enhance. Calvarial metastases typically enhanced with Gd-DTPA. Enhanced MR images were superior to nonenhanced studies for detecting subtle intradiploic metastases but were inferior to nonenhanced studies for detecting tumor extension into fat-containing areas. Careful comparison of nonenhanced and enhanced MR images is required for complete evaluation of lesions affecting the calvaria and skull base.

Contrast Media↗
PubMed1990

Benign lumbar arachnoiditis: MR imaging with gadopentetate dimeglumine.

MR imaging was performed in 13 patients with benign lumbar arachnoiditis both before and after IV injection of gadopentetate dimeglumine. The arachnoiditis was proved by previous myelography in 12 patients and by noncontrast MR imaging in one patient. The disease was presumably the result of previous myelography and/or surgery. It was characterized as mild in two patients, moderate in two patients, and severe in nine patients. Imaging was performed on a 1.5-T unit, and both short and long TR images were obtained before and after contrast administration. Noncontrast MR images demonstrated changes consistent with arachnoiditis in all patients. After contrast, three patients had no enhancement, three patients had minimal enhancement, three patients had mild enhancement, and four patients had moderate enhancement. In no case did contrast enhancement alter the diagnosis or reveal additional findings that could not be seen on the noncontrast images. Gadopentetate dimeglumine enhancement plays little role in the diagnosis of lumbar arachnoiditis. If used for another reason, however, short TR scans may show enhancement of adherent roots in some cases. In addition, administration of gadopentetate dimeglumine will not cause sufficient enhancement to hinder the detection of arachnoiditis on long TR images and may aid in recognition of adherent roots on short TR images.

Adult↗
PubMed1990

Magnetic resonance imaging contrast agents: theory and application to the central nervous system.

The theoretical aspects of magnetic resonance (MR) imaging contrast agents are reviewed, and their current applications to the central nervous system (CNS) and their future applications are discussed. Profound differences exist between contrast agents used for MR imaging and computerized tomography (CT). In MR imaging, the contrast agents are not imaged directly but rather act on adjacent protons to shorten T1 and T2 relaxation times. This in turn results in signal intensity changes. The lanthanide metal, gadolinium, in the form of gadopentetate dimeglumine, has been found to be both safe and efficacious as the only currently approved contrast agent for MR imaging. Magnetic resonance imaging revolutionized the detection and treatment of disease affecting the brain and spine. Initially, it was thought that signal characteristics on MR imaging would allow differentiation of specific pathology. It was soon found that MR studies were able to detect more abnormalities but were less able to characterize them. The recent development of contrast agents for MR imaging has allowed this modality to surpass CT for the evaluation of most CNS lesions. At present, contrast-enhanced MR imaging is generally accepted as the study of choice for evaluating acoustic neurinomas, pituitary lesions, meningeal disease, primary and secondary brain tumors, active multiple sclerosis, intradural spinal neoplasms, intramedullary spinal disease, and postoperative states in both the spine and brain. Even when contrast-enhanced CT can detect the same abnormalities, evaluation of the lesions in multiple planes on MR imaging can sometimes yield invaluable information, especially prior to surgery. Future developments of contrast material for MR imaging include non-gadolinium compounds, intrathecal contrast media, cerebral blood flow and volume evaluation, and, possibly, antibody-labeled contrast agents.

Animals↗
PubMed1989

Spinal lesions: quantitative and qualitative temporal evolution of gadopentetate dimeglumine enhancement in MR imaging.

Seventy gadolinium-enhanced magnetic resonance imaging studies were reviewed, and 36 were selected for quantitative and qualitative analysis of the temporal evolution of contrast medium enhancement of spinal lesions. In the extradural space, lesions often showed mild increase of enhancement on delayed images, but enhancement was always visible on immediate postcontrast images. In the intradural extramedullary space, tumor nodules demonstrated most prominent enhancement on early images, although subtle, strandlike enhancement of the nerve roots showed some delayed uptake of contrast medium on later images. In the intramedullary space, enhancement often increased on delayed images, although this increase was usually mild. For clinical purposes, immediate postcontrast imaging should be sufficient to depict the majority of spinal lesions, regardless of location. However, selected cases, such as necrotic spinal cord tumors, will require delayed imaging.

Contrast Media↗
PubMed1989

Benign and malignant sinonasal lesions with intracranial extension: differentiation with MR imaging.

Most sinonasal lesions that extend into the anterior cranial fossa are malignant tumors. However, benign inflammatory polypoid disease can also rarely be manifested in this manner. Fourteen surgically proved cases of such benign and malignant disease were studied with magnetic resonance (MR) imaging. The appearances of the benign and the malignant lesions were quite different and allowed the seven chronic polypoid lesions to be distinguished from the tumors. The benign lesions had nonhomogeneous appearances on MR images due primarily to varying degrees of free-water resorption and protein concentration. The tumors had primarily homogeneous low-to-intermediate signal intensities due to their highly cellular composition.

Carcinoma, Squamous Cell↗
PubMed1989

Trigeminal neuralgia: MR imaging features.

Magnetic resonance (MR) imaging was used to evaluate the relationship of the cisternal portion of the fifth cranial nerve to surrounding vascular structures in six patients with documented trigeminal neuralgia and in 85 asymptomatic patients. MR imaging clearly demonstrated the course of the fifth nerve from its root entry zone (REZ) to the Meckel cave and its relationship to the surrounding vertebrobasilar system. In the six patients with trigeminal neuralgia, the presence of a vascular structure at the REZ of the fifth nerve was identified. In the 85 asymptomatic patients, examination of 170 trigeminal nerves revealed that 30% had contact between a vascular structure and the fifth nerve at the REZ, but only 2% had actual deformity. These results indicate that although neurovascular contact may be asymptomatic, MR demonstration of a vascular structure at the REZ of the fifth cranial nerve in a patient with trigeminal neuralgia may implicate this as the cause of symptoms, which may influence the treatment of choice. Because of the inherent limitations of computed tomography in the visualization of posterior fossa structures, MR imaging should be considered the initial screening procedure in the assessment of patients with trigeminal neuralgia.

Adult↗
PubMed1989

MR imaging of hemorrhagic intracranial neoplasms.

Thirty patients with intracranial tumors containing hemorrhage of varying stages were examined with high-field-strength MR imaging and CT to determine what differences might exist between hemorrhagic tumor and pure hemorrhage. Pathology was obtained in the six patients with primary tumors and in 14 of the 24 patients with metastases. Similar to evolving intraparenchymal hematomas, hemorrhagic neoplasms undergo changes in their appearance that can be categorized into three distinct intensity patterns, or stages. Stage 1 is characterized as iso- or hypointensity on short TR sequences and as hypointensity on long TR sequences; stage 2 as developing hyperintensity on both short and long TR sequences, without evidence of a well-defined black rim; and stage 3 as a hyperintense lesion with a well-defined black rim on long TR sequences. An additional mixed-intensity pattern was identified, which contained areas corresponding to more than one stage. In all of the cases exhibiting this pattern, pathology confirmed that the appearance was due to recurrent bleeding. We found several characteristics on MR that, when present, suggest an underlying neoplasm. These include delay in evolution between stages, central or eccentric hyperintensity in stage 2, and a mixed-intensity pattern. In addition, the presence of a hemosiderin rim does not exclude an underlying neoplasm. We found that the MR patterns that characterize hemorrhagic intracranial neoplasms should help to determine the cause of the hemorrhage.

Adult↗
PubMed1989

MR imaging of the cranial meninges with emphasis on contrast enhancement and meningeal carcinomatosis.

MR imaging was used to investigate normal and abnormal meningeal enhancement, with an emphasis on meningeal carcinomatosis. Three groups of patients were studied on a 1.5-T system. In group 1, the normal meninges were examined in 20 patients and were found to show fine linear enhancement in short segments, especially in a parasagittal distribution. In group 2, all gadolinium-enhanced head scans were reviewed retrospectively. Abnormal meningeal enhancement was detected in 52 patients. In some of these, the enhancement was associated with pathologic conditions of the meninges, including leptomeningeal tumor and meningeal infections and other inflammatory conditions; in others the enhancement was adjacent to subdural hematomas, subacute infarcts, and skull lesions, such as metastases or postoperative defects. In group 3, 30 cases of meningeal carcinomatosis were studied prospectively. Enhancement was seen in approximately two-thirds of cases and usually was quite diffuse and applied to the inner table of the skull. Frank nodules were seen less often. Contrast-enhanced CT was equal to MR in the detection of nodules but was nearly always unable to show diffuse meningeal enhancement against the inner table of the skull. Contrast-enhanced MR was more sensitive than contrast-enhanced CT in the examination of normal and abnormal meninges. Abnormal findings, such as meningeal carcinomatosis, were demonstrated more often by MR than by CT.

Adolescent↗
PubMed1988

Chordomas: MR imaging.

Twenty histologically verified intracranial and upper cervical chordomas were retrospectively studied with both magnetic resonance (MR) imaging and computed tomography (CT), and the advantages of each modality were compared with regard to three criteria: detection of tumor, delineation of extent of tumor, and characterization of tumor. MR imaging and CT were equivalent in permitting the detection of chordomas. MR imaging was considerably better in delineating the full extent of the tumor, which would influence establishment of treatment. MR imaging also provided a degree of histologic specificity that would be useful in prognosis.

Adult↗