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Short-Ti inversion-recovery pulse sequence: analysis and initial experience in cancer imaging 总被引:2,自引:0,他引:2
Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy. 相似文献
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Sixteen cases of histopathologically proved solitary rectal ulcer syndrome were encountered. Fifteen patients underwent barium enema study; in nine cases the findings--including rectal stricture, granularity of the mucosa, and thickened rectal folds-were nonspecific. In six cases the study was normal. All patients had a long history of defecation disorders, and defecography was performed in all. In seven cases, intussusception of the rectal wall was seen; in another case the intussusception was accompanied by a rectocele. One case showed rectal prolapse. In four cases, failed relaxation of the puborectalis occurred and prevented the passage of the bolus; in another case there was abnormal perineal descent. In two patients studies were normal. In patients with defecation disorders, the possibility of this syndrome should be considered. Defecography is the method of choice for establishing the diagnosis. 相似文献
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W N Kelly E C Krause W J Krowinski T R Small J F Drane 《American journal of hospital pharmacy》1990,47(10):2245-2250
Whether and how drug information centers respond to calls from the public that involve ethical issues was studied. A survey describing six ethical dilemmas typical of those presented by calls from the public was mailed to pharmacists in 154 drug information centers to see how the questions would be handled. Centers that had written policies governing responses to questions with ethical implications were asked to submit those policies. One hundred twenty-six centers (82%) responded to the survey; of these, 81 (64.3%) answered questions from the public. There were no significant differences in characteristics between centers that did and did not respond to public calls. The case analyses, completed only by pharmacists in centers that responded to public calls, covered such issues as invasion of privacy, social responsibility, personal liability, and interference with the patient-physician relationship. Respondents exercised a wide degree of discretion in determining if they would answer a question; for example, while only 4% would not answer a question concerning the efficacy of a weight-loss diet patch, 77% reported they would not respond to a caller asking for information on drugs that could interfere with the results of a polygraph test. Although respondents often cited institutional policy as the reason for failing to respond to a question, none submitted a copy of such a policy. The pharmacists' responses indicated a high degree of moral and social sensitivity; nonetheless, written policies should be developed to assist drug information center staff members in handling questions that have ethical implications. 相似文献
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