Biomedical subjects
Publications and source records attributed to M H Lev.
Neurologic complications of Hodgkin's disease (HD) include both metastatic and non-metastatic involvement of the nervous system. There are at least five paraneoplastic syndromes associated with HD but chorea has not been described. We report the first choreiform disorder as a paraneoplastic complication of HD and only the second case of paraneoplastic chorea in the literature.
PURPOSE: Our purpose was to determine the clinical feasibility of quantitative three-dimensional functional CT in patients with hyperacute stroke. METHODS: Twenty-two patients who underwent clinically indicated CT angiography were studied: nine patients had no stroke, eight had mature stroke, and five had hyperacute stroke (less than 3 hours since ictus). Maps were obtained of perfused cerebral blood volume (PBV), and CT angiograms were generated by using standard techniques. RESULTS: Normal PBV values (mean +/- SEM) were 4.6 +/- 0.15% in the gray matter, 1.75 +/- 0.09% in the white matter, 2.91 +/- 0.20% in the cerebellum, 3.18 +/- 0.10% in the caudate, 2.84 +/- 0.23% in the putamen, 2.92 +/- 0.29% in the thalamus, and 1.66 +/- 0.03% in the brain stem. For patients with mature stroke, ischemic changes were visible on noncontrast, contrast-enhanced, and PBV scans. In patients with hyperacute stroke, ischemic changes were either absent or subtle before contrast administration, but became apparent on contrast-enhanced scans. Quantitative PBV maps confirmed reduced regional perfusion. CT angiograms in the hyperacute group showed occlusion of vessels in locations appropriate to the PBV deficits seen. CONCLUSION: Quantitative three-dimensional functional CT is feasible for patients with hyperacute stroke. It is performed by using helical CT techniques, and yields measures of cerebrovascular physiological function, which are useful in this patient population.
The complex anatomy of the larynx, best conceptualized as a set of mucosal folds draped over a cartilaginous skeleton, has developed as a consequence of its many upper airway functions. Despite its deep location in the neck, much of the mucosal surface of the larynx is amenable to direct laryngoscopic inspection. The role of the radiologist in laryngeal imaging, therefore, is not primarily to diagnose disease, but to aid in both surgical staging and in the evaluation of potential clinical "blind spots." In this article, the normal anatomy of the larynx is reviewed, with special attention to important surgical and functional structures.
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PURPOSE: To evaluate acute stroke with conventional, multisection diffusion-weighted (DW), and hemodynamically weighted (HW) magnetic resonance (MR) imaging. MATERIALS AND METHODS: The three MR imaging techniques were performed in 11 patients within 10 hours of the onset of acute hemiparesis. The volume of DW and HW abnormalities were compared with infarct volumes depicted at initial and/or follow-up MR or computed tomography (CT). RESULTS: Findings at DW and HW imaging were abnormal in nine of the 11 patients, despite normal findings at initial CT and/or MR. In all nine patients, infarcts were depicted at follow-up CT or MR. The DW abnormality was generally smaller and the HW abnormality was generally larger than the infarct volume determined at subsequent imaging. In the two patients with normal findings at DW and HW imaging, symptoms resolved completely within 1-48 hours. CONCLUSION: Different aspects of hyperacute cerebral ischemia are depicted at DW and HW imaging before infarction is depicted at conventional MR or CT. These techniques may improve stroke diagnosis and may contribute to advances in treatment.
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The purpose of this study was to investigate the dependence of contrast-to-noise ratio (CNR) on the dose and rate of sprodiamide injection in magnetic resonance relative cerebral blood volume (rCBV) imaging. rCBV maps for 35 normal volunteers were constructed from dynamic MR image sets acquired with echo-planar spin-echo imaging after intravenous injection of sprodiamide. Doses of .1, .2, and .3 mmol/kg, at rates of 2 ml/second and 5 ml/second, were tested. CNRs and blood/volume ratios of gray to white matter were computed. CNR depended on dose (P < .0001) but was independent of injection rate (P < .69). rCBV ratios of gray to white matter were dose independent (P < .38) and rate independent (P < .97). The dependence of CNR on dose, but not injection rate, has practical implications in optimal protocol design. The independence of gray/white ratios supports the theory underlying the generation of rCBV maps.
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PURPOSE: The purpose of this work was to evaluate the accuracy of CT angiography (CTA) for the detection of large vessel intracranial thrombus in clinically suspected hyperacute (<6 h) stroke patients. METHOD: Forty-four consecutive intraarterial thrombolysis candidates underwent noncontrast CT followed immediately by CTA. Axial source and two-dimensional collapsed maximum intensity projection reformatted CTA images were rated for the presence or absence of large vessel occlusion. Five hundred seventy-two circle-of-Willis vessels were reviewed; arteriographic correlation was available for 224 of these. RESULTS: Sensitivity and specificity for the detection of large vessel occlusion were 98.4 and 98.1%; accuracy, calculated using receiver operating characteristic analysis, was 99%. Mean time for acquisition, reconstruction, and analysis of CTA images was approximately 15 min. CONCLUSION: CTA is highly accurate for the detection and exclusion of large vessel intracranial occlusion and may therefore be valuable in the rapid triage of hyperacute stroke patients to intraarterial thrombolytic treatment.
A prototype system optimized for automatic registration of CT scans and applications such as subtraction enhancement and CT angiography was evaluated. Co-registration was performed on 50 studies of various types, including CT angiograms. Mean registration speed was 109 s; accuracy was 2.0 mm. Examples of subtraction enhancement and automatic extraction of the vascular tree are provided. Unattended registration was demonstrated in routine application. Subtraction-enhanced images and extraction of the vascular tree may be useful in clinical practice.
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BACKGROUND AND PURPOSE: Weak or absent CT enhancement in pleomorphic adenomas of the parotid gland has been observed immediately after i.v. contrast administration. This feature can result in poor lesion conspicuity relative to both normal parotid tissue and other parotid abnormalities. The purpose of this study was to document the delayed CT enhancement characteristics of parotid pleomorphic adenomas and to preliminarily compare these results with the enhancement characteristics of other parotid gland tumors. METHODS: Preoperative CT scans from 18 pathologically proved parotid gland neoplasms were reviewed retrospectively. Lesions included eight pleomorphic adenomas, four Warthin's tumors, two squamous cell carcinomas, two mucoepidermoid cancers, one acinic cell carcinoma, and one melanoma metastasis. In all cases, axial CT was performed after the administration of 100 to 150 mL of i.v. contrast material, followed by delayed (average, 24 minutes; range, 13 to 34 minutes) coronal CT scanning. The mean normalized Hounsfield unit (HU) attenuation of each lesion was computed by drawing a region of interest around the entire mass and dividing the resulting HU value by that of the contralateral uninvolved parotid gland. RESULTS: For all eight pleomorphic adenomas, the degree of contrast enhancement increased and became progressively more uniform with time. Mean normalized axial lesion enhancement averaged 1.20 +/- 0.35 at 8 minutes, compared with 2.30 +/- 0.66 on the coronal scans at 24 minutes. For the 10 nonpleomorphic adenomas, no significant change was found in either the degree or pattern of contrast enhancement between the immediate and delayed CT scans. In these tumors, peak enhancement was reached early, during axial scanning. CONCLUSION: Delayed CT contrast enhancement is observed in parotid pleomorphic adenomas, increasing in both degree and homogeneity with time. This feature may be useful in selecting an appropriate contrast delay when scanning possible pleomorphic adenomas to improve lesion conspicuity and, potentially, to better distinguish these tumors from other parotid abnormalities.