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排序方式: 共有3872条查询结果,搜索用时 15 毫秒
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Colin J McKay 《World journal of surgery》2006,30(12):2234-2235
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Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
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Massachusetts State Program for the Care of Prematures 总被引:2,自引:0,他引:2
McKay FL 《American journal of public health and the nation's health》1941,31(1):72-78
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Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions 总被引:2,自引:0,他引:2
Babette Zemel Shona Bass Teresa Binkley Gaele Ducher Heather Macdonald Heather McKay Laurie Moyer-Mileur John Shepherd Bonny Specker Kate Ward Didier Hans 《Journal of clinical densitometry》2008,11(1):59-74
Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established. 相似文献
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Maxillary sinusitis in adults: an evaluation of placebo-controlled double-blind trials 总被引:1,自引:0,他引:1
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed
and treated with antibiotics. OBJECTIVE: This study aimed to determine the
evidence for the effectiveness of antibiotic treatment in acute maxillary
sinusitis in adults by assessing the methodological quality of
placebo-controlled double-blind randomized trials. METHOD: An evaluation by
four raters through a 35-item scoring-scale for internal and external
validity of all placebo-controlled double-blind randomized trials on acute
sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five
trials were excluded because they were not placebo-controlled,
double-blind, randomized, or were carried out in patients with chronic
sinusitis or in children. The three remaining trials were performed in
different populations (one in general practice) between 1973 and 1978. Only
one study claimed superiority of antibiotic treatment. Different inclusion
criteria and major outcome measures were used by the authors. The
reliability of major outcome events was reported poorly or not at all and
in two studies outcome measures were clinically inappropriate. The studies
scored 30-62% of the maximum attainable score for internal validity and
10-20% for external validity. CONCLUSION: The effectiveness of antibiotic
treatment in acute maxillary sinusitis in a general practice population is
not based sufficiently on evidence.
相似文献
10.
Noah D Silverberg Robin A Hanks Cherisse McKay 《Journal of the International Neuropsychological Society》2007,13(5):898-902
The present study explores the construct and ecological validity of the Biber Cognitive Estimation Test (BCET) in a traumatic brain injury (TBI) sample. Participants completed the BCET in the course of a neuropsychological evaluation at 1-15 years after injury. BCET scores correlated moderately with other standard measures of executive functioning, and contrary to our hypotheses, at least as high with neuropsychological tests with minimal demands on executive functioning. Moreover, partialing out the portion of BCET variance not attributable to executive functioning markedly attenuated the former correlations. With respect to ecological validity, BCET scores did not predict concurrent functional status, as measured by the Disability Rating Scale. By comparison, standard measures of executive functioning strongly correlated with each other, correlated less strongly with nonexecutive functioning measures, and predicted functional status. In conclusion, unlike standard measures of executive functioning, the BCET demonstrated poor construct and ecological validity in TBI patients. 相似文献