Biomedical subjects
G Sze
Publications and source records attributed to G Sze.
Totally cystic schwannoma of the tenth cranial nerve mimicking an epidermoid.
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Fast spin-echo imaging in the evaluation of intradural disease of the spine.
PURPOSE: Fast spin echo (FSE) images were compared with conventional images in 46 patients with intradural spinal disease to determine their accuracy in the detection and delineation of lesions. MATERIALS AND METHODS: The images were interpreted by two neuroradiologists, who read individually. A total of 720 blinded readings formed the basis for this evaluation. A gold standard for each patient was selected, based on the blinded readings of the conventional studies. RESULTS: In the sagittal plane, the FSE sequences were found to have an accuracy of 93% and 93% for the first reader and 93% and 85% for the second reader. For the axial plane, the corresponding figures were 86% and 82% for the first reader and 64% and 77% for the second reader. These figures compared favorably with conventional sequences. Similar delineation of lesions was noted in 78% of cases. In the remaining cases, there were no significant trends. CONCLUSION: Because of these findings, FSE sequences appear as accurate as conventional sequences. In this study, they were capable of supplanting conventional sequences in the evaluation of intradural pathology of the spine in the sagittal plane, although conventional sequences were still preferred in the axial plane.
Cranial osteopetrosis: MR findings.
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MR imaging of intradural inflammatory diseases of the spine.
Twenty-eight patients with intradural inflammatory disease of the spine were studied in order to characterize the MR imaging findings of infectious and inflammatory conditions. Patients were categorized according to the spinal compartment involved. Among the 12 patients in the intradural extramedullary group, unenhanced scans were either normal or nonspecific while contrast-enhanced scans were helpful in visualizing and localizing the lesion. Nevertheless, contrast-enhanced MR studies were unable to differentiate infection and inflammation from tumor in this compartment. Among 16 patients with intramedullary lesions, four had granulomatous disease and 12 had nongranulomatous disease. The granulomatous lesions resembled tumors and displayed MR characteristics of a focal lesion with large nodular enhancement. The patients with nongranulomatous intramedullary lesions exhibited two subsets of MR findings. In the first subset of nine patients, diffuse cord swelling and high signal were seen on long TR images, combined with either no enhancement or peripheral, diffuse, or speckled enhancement of the spinal cord on contrast-enhanced short TR images. In the second subset of three patients, minimal or no spinal cord swelling was displayed despite the visualization of high signal on long TR scans and nodular enhancement with contrast administration on short TR scans. Both subsets were sufficiently unique that nongranulomatous myelitis could usually be differentiated from spinal cord tumors.
Hemifacial spasm: MR imaging features.
MR imaging was used to evaluate the relationship of the root exit zone of the seventh cranial nerve to surrounding vascular structures in 13 patients with clinically documented hemifacial spasm and in 70 asymptomatic patients. MR imaging clearly demonstrated the course of the seventh nerve from the root exit zone of the brainstem to the internal auditory canal and its relationship to the surrounding vertebrobasilar system. The presence of a vascular structure at the root exit zone of the seventh nerve was identified in all 13 patients with hemifacial spasm. In the 70 asymptomatic patients, examination of 140 seventh nerves revealed that 21% had contact by a vascular structure at the root exit zone of the seventh nerve. Our results indicate that although neurovascular contact may be asymptomatic, MR demonstration of a vascular structure at the root exit zone of the seventh cranial nerve in a patient with hemifacial spasm may implicate neurovascular compression as the cause of symptomatology. This finding may alter therapeutic management. Because of the inherent limitations of CT in the visualization of posterior fossa structures, MR imaging should be considered the initial screening procedure in the assessment of patients with hemifacial spasm.
Imaging findings in hippocampal sclerosis: correlation with pathology.
We evaluated the ability of preoperative radiologic imaging to detect hippocampal sclerosis in 31 patients who underwent surgery for intractable epilepsy. Hippocampal sclerosis is commonly associated with surgically treatable temporal lobe epilepsy. It is pathologically described as neuronal cell loss with associated gliosis in the hippocampus. While previous reports have correlated imaging results with clinical or qualitative histologic findings, this study used quantitative pathologic criteria (neuronal cell density) to diagnosis hippocampal sclerosis. We focused our study on the 11 patients with cryptogenic temporal lobe epilepsy. Of these, nine had hippocampal sclerosis by pathologic criteria. MR findings included unilateral hippocampal atrophy, an increased signal in the hippocampus on long TR scans, and atrophy in the adjacent white matter and temporal lobe. Hippocampal atrophy was most frequently seen in the red nucleus plane on coronal scans, corresponding to the body of the hippocampus. We also compared hippocampal size on MR with neuronal density in surgical specimens of the 11 patients with cryptogenic temporal lobe epilepsy. A statistically significant correlation was found between MR size and neuronal density in CA3 and CA4 of the cornu ammonis and the granular cell layer of the hippocampus. Since temporal lobectomy eliminated seizures in seven of nine patients with hippocampal sclerosis, preoperative diagnosis by MR has important therapeutic consequences.
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.
Detection of brain metastases: comparison of contrast-enhanced MR with unenhanced MR and enhanced CT.
Contrast-enhanced MR studies were compared with noncontrast MR and contrast-enhanced CT scans in the evaluation of intraparenchymal brain metastases. Fifty consecutive inpatients were studied with short and long repetition time (TR) sequences before and after the administration of gadopentetate dimeglumine. In addition, a delayed short TR sequence was performed. The contrast CT, noncontrast MR, immediate postcontrast short TR sequence, postcontrast long TR sequence, and delayed postcontrast short TR sequence were each read blindly and independently by two neuroradiologists. These results were then compared with a final interpretation, reached by all the neuroradiologists in the study, using all the clinical information and imaging findings. Postcontrast short TR scans proved to be superior to other sequences. They were particularly useful in the detection of metastases in the posterior fossa and cortex. The delayed postcontrast short TR scan held no definite advantage over the immediate postcontrast short TR scan, although metastases were sometimes seen slightly better after the delay. While long TR sequences were not always sensitive or specific, they often did provide ancillary information and were particularly useful in cases of hemorrhagic metastases. Because of these findings, we recommend that the evaluation of intraparenchymal metastases consist of a single postcontrast long TR scan followed by a single postcontrast short TR scan. While these sequences should be very accurate in the detection of metastases, we also generally perform a single precontrast short TR scan as well, since the question of hemorrhage or bone lesion may be clinically relevant.
Multicenter study of gadopentetate dimeglumine as an MR contrast agent: evaluation in patients with spinal tumors.
In an open-label, multicenter study, the efficacy and safety of gadopentetate dimeglumine (0.1 mmol/kg) administered IV as an MR imaging contrast agent were evaluated in 113 patients with symptoms of spinal tumors. The examinations were performed with a variety of imagers at different field strengths. Scans with short and long TRs were obtained in all patients before and after IV administration of the contrast medium. Contrast enhancement was seen in 77% of patients. No enhancement was seen in 23%, but this absence was useful diagnostic information in all cases. In 66% of the cases, additional information regarding location, size, configuration, and/or characterization of the lesion was obtained from postcontrast scans. The investigators made a change from referral diagnosis to postinjection diagnosis in 30% of the cases. Postinjection images provided additional information in 96% (43/45) of intradural extramedullary and intramedullary tumors; it also provided additional information in 20 (53%) of 38 cases of extradural tumor. Gadopentetate dimeglumine demonstrated a high level of safety and tolerance, as evidenced by the lack of clinically significant trends toward abnormal changes from baseline evaluations for physical and neurologic examinations, vital signs, and hematologic and blood chemistry parameters and by the low prevalence and mild nature of adverse reactions. Gadopentetate dimeglumine was found to be efficacious in the evaluation of suspected spinal tumors. High levels of safety and tolerance were demonstrated.
Intradural metastases of chordoma.
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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.
Table-top support plate for imaging the entire spine with surface-coil MR.
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Preoperative localization of intracranial lesions on MR.
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Dural sinus thrombosis: verification with spin-echo techniques.
Although MR imaging is being used increasingly to detect dural sinus thrombosis, accurate evaluation of images has often been hindered by the presence of artifacts, especially flow-related enhancement, that may simulate intraluminal clot. We tried an approach with spin-echo techniques to eliminate flow-induced artifacts and, thus, facilitate the diagnosis of dural sinus thrombosis. In this investigation, a nonselective single-section spin-echo verification method was used as a prototype of this approach. Both patients and an experimental flow phantom were used to test the validity of this concept. Clinically, thrombosis was seen to persist as isointense or highly intense signal in the vascular lumina with the specialized sequence, while flow-related artifacts were replaced by hypointense signal, but not by signal void. These same changes were examined both quantitatively and qualitatively in the flow phantom by using varying velocities of flow. Although our clinical investigation concerns suspected dural sinus thrombosis, the principles of these specialized spin-echo techniques can be applied successfully throughout the head to eliminate certain flow-related artifacts.
Fast spin-echo MR imaging of the cervical spine: influence of echo train length and echo spacing on image contrast and quality.
PURPOSE: To examine the interaction of echo train length and interecho spacing and their effects on image quality and contrast in fast spin-echo sequences of the cervical spine. METHODS: Forty-three patients with suspected cervical disk disease were prospectively evaluated with fast spin-echo with varying echo train lengths and interecho spacing. A flow phantom was used to confirm findings related to cerebrospinal fluid pulsation. Parameters were manipulated to adjust contrast, signal-to-noise ratio, the effects of artifacts, and the speed of acquisition. RESULTS: In general, increasing echo train length increased homogeneity and high intensity of cerebrospinal fluid signal and reduced acquisition time; however, it decreased the signal-to-noise ratio of cerebrospinal fluid and cord and increased blurring, and, to a lesser extent, edge enhancement, and "truncation-type" artifact. Increasing interecho space permitted the use of longer echo times but minimally decreased contrast and signal-to-noise ratio of cord and cerebrospinal fluid. In addition, increasing echo spacing increased blurring, edge enhancement, truncation-type, magnetic susceptibility, and motion artifacts. CONCLUSIONS: For cervical spine imaging, a long echo train length and short echo spacing partially compensate for cerebrospinal fluid flow and produce the best myelographic effect but must be modulated by other constraints, such as artifact production or technical capabilities.
Vasculitis presenting as primary leptomeningeal enhancement with minimal parenchymal findings.
In this case of biopsy-proved granulomatous angiitis, MR showed prominent leptomeningeal enhancement with comparatively little parenchymal involvement. Pathologically, granulomatous angiitis chiefly affects small vessels, with a predilection for those in the leptomeninges. Although marked leptomeningeal enhancement is not the most common finding, vasculitis should be added to the differential diagnosis of this MR appearance.
Cystic pituitary mass in neurosarcoidosis.
An MR examination in a patient with neurosarcoidosis showed an intrasellar cystic mass extending into the suprasellar space. The wall of the mass was thick, it enhanced after administration of contrast material, and it extended into the infundibulum and hypothalamus. Pathologic findings showed noncaseating granulomatous inflammation; the cystic component was considered to be ischemic necrosis of the intracranial sarcoid mass.