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MR imaging of primary epidermoid tumors 总被引:2,自引:0,他引:2
D J Steffey G J De Filipp T Spera T O Gabrielsen 《Journal of computer assisted tomography》1988,12(3):438-440
The magnetic resonance (MR) imaging characteristics of five primary intradural epidermoid tumors are described. At 0.35 T, the most consistent finding on spin echo imaging was a tumor signal intensity that differed from brain and CSF. On T1-weighted images [repetition time (TR) 0.5 s, echo time (TE) 30-40 ms] all tumors exhibited a signal intensity intermediate between brain and CSF. On moderately T2-weighted images (TR 2.0 ms, TE 60-80 ms) the tumor signal intensity was greater than brain and CSF in all cases. The tumor signal consistency was mixed in four of five lesions and homogeneous in one. The tumor margins were well defined in all cases; in three cases the tumor margins were irregular, in one case smooth, and in the last case, one margin was irregular and the remaining margins were smooth. These findings are contrasted with the MR appearance of arachnoid cysts. Using identical imaging factors, four arachnoid cysts were studied and exhibited a homogeneous signal intensity that was identical to CSF on all pulse sequences; their margins were smooth and well defined in each case. These MR findings contribute to the characterization of extraaxial lesions. 相似文献
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Christopher J. Roth M.D. William J. Weadock M.D. Michael A. DiPietro M.D. 《Journal of digital imaging》2005,18(2):85-90
Medical students on the radiology elective in our institution create electronic presentations to present to each other as part of the requirements for the rotation. Access was given to previous students presentations via the web-based system, Medical Imaging Resource Center (MIRC) project, created and supported by the Radiological Society of North America (RSNA). RadPix Power 2 MIRC (Weadock Software, LLC, Ann Arbor, MI) software converted the Microsoft PowerPoint (Redmond, WA) presentations to a MIRC-compatible format. The textual information on each slide is searchable across the entire MIRC database. Future students will be able to benefit from the work of their predecessors. 相似文献
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Adler RS Bell DS Bamber JC Moskovic E Thomas JM 《AJR. American journal of roentgenology》1999,172(3):781-788
OBJECTIVE: We report our initial experience with segmented color Doppler velocity-based estimates of tumor vascularity for various histogically proven soft-tissue masses. SUBJECTS AND METHODS: Color Doppler sonography of 23 histologically proven masses in 22 patients was performed. Digital color Doppler images were acquired directly off the scanner output or from video recordings and stored on a personal computer as 24-bit gray-scale and color composite images. A color Doppler velocity segmentation and analysis algorithm was applied to the digital images, from which we calculated the normalized percentage of color Doppler area. Normalization was determined by expressing color Doppler area as a percentage of the area enclosed by a preselected region of interest. We also calculated mean percentage, SD, and cumulative distribution of color Doppler area, relative to a fixed threshold, for the acquired image data sets. RESULTS: Estimates of mean percentage of color Doppler area showed a dynamic range of at least two or three orders of magnitude between lowest and highest values obtained. A scatterplot of mean percentage of color Doppler area versus SD of percentage of color Doppler area showed a linear monotonic relationship (r2 = .92), illustrating increasing vascular heterogeneity with mean vascularity. Preliminary data also suggest the presence of at least two distinct groups of masses (p < .0001) based on these vascularity estimates. One group corresponds to high-grade lesions in which tumor angiogenesis is expected to be important in predicting biologic behavior. The second group appeared to have little or no relationship to tumor vascularity or was of an intermediate (or lower) histologic grade. CONCLUSION: Quantitative color Doppler estimates of tumor vascularity can be obtained over a wide dynamic range. Such estimates provide a mechanism to assess vascular heterogeneity of soft-tissue tumors. Preliminary data suggest that two biologically distinct groups of masses may be separable on the basis of quantitative velocity-based estimates of tumor vascularity as obtained from color Doppler sonography. 相似文献
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Craving is thought to play an important role in maintaining regular smoking patterns in current smokers, and in leading to
relapse in smokers attempting to quit. Within the scientific community however, the concept is surrounded by controversy.
In an effort to 1) identify interventions that can reliably influence cigarette cravings, and 2) assess the relationship between
cigarette craving and smoking behavior, effects of aversive rapid smoking (up to nine cigarettes with puffs taken every 6 s)
on self-reported craving and subsequent smoking behavior were compared to effects of self-paced smoking or no smoking. Subjects
(n = 14) engaged in a rapid, self-paced or no smoking procedure at the start of three separate sessions. Craving levels, measured
repeatedly during the next 3 h of no smoking, were significantly lower after rapid smoking than after either self-paced or
no smoking. Measures of subsequent smoking behavior (latency to first cigarette, number of cigarettes, number of puffs) did
not differ systematically across conditions. Thus, craving was reliably suppressed by aversive rapid smoking, but craving
scores did not predict actual smoking behavior.
Received: 2 April 1998/Final version: 7 August 1998 相似文献
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Lorenz M Evering WE Provencher A Blue JT Lewis HB Hazelette JR Rajagopalan P Meunier PC Car BD 《Toxicology and applied pharmacology》1999,155(3):227-236
DMP 406 is an atypical antipsychotic, antischizophrenic drug, biochemically related to clozapine, which exerts its desired pharmacologic effects through selective antagonism of 5-hydroxytryptamine and dopamine-receptor subtypes. Clozapine therapy is clinically associated with severe granulocytopenia in a small subset of patients. In the course of a 3-month toxicity study in dogs, severe neutropenia, thrombocytopenia, marked myeloid and erythroid left-shifted bone marrow hyperplasia with increased erythrophagocytosis, positive Coombs' tests, and hypergammaglobulinemia occurred in individual females dosed with 30 mg/kg/day of DMP 406. Related but less severe changes were also observed in males. Sera or purified immunoglobulins from affected and control dogs were tested in methylcellulose-based, canine hematopoietic colony-forming unit (CFU) assays with or without DMP 406. Neither size nor number of erythroid or myeloid CFUs differed between cultures containing control or affected dog serum components. Sera from individual affected dogs but not controls resulted in moderate numbers of fibroblast-like CFUs, suggesting DMP 406-associated marrow stromal cell-modifying, serum activities to be present. DMP 406 alone resulted in a concentration-dependent reduction of erythroid and myeloid CFUs with an approximate IC50 of 3.0 microg/mL. Taken together, DMP 406-induced granulocytopenia and bone marrow dyscrasia appear likely to result from both immune-mediated and direct drug-induced myelotoxicity. 相似文献
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Sheryl L. Chow Tien M.H. NgRoman A. Litwinski Simon KangavariMason Weiss 《International journal of cardiology》2012,154(1):17-21