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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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Leslee J. Shaw Romalisa Miranda-Peats Piotr Slomka John Friedman Sean W. Hayes Daniel S. Berman Gary V. Heller Marcin Dada William E. Boden Paul Casperson Robert A. O’Rourke Ronald Schwartz William S. Weintraub David J. Maron Spencer King Koon Teo Pamela Hartigan 《Journal of nuclear cardiology》2006,13(5):685-698
Background Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after
intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical
outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial.
Methods and Results The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical
therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been
designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia
at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship
between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate
the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization
patients. Substudy 2 (n _ 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic
intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive
risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization
in reducing patients’ ischemic burdens.
Conclusions The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology.
We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based
management of patients with stable coronary disease.
The COURAGE trial was supported by the Cooperative Studies Program of the Department of Veterans Affairs Office of Research
and Development in collaboration with the Canadian Institutes of Health Research. Unrestricted research grants were obtained
from Merck & Co; Pfizer Pharmaceuticals; Bristol-Myers Squibb Medical Imaging; Astellas Pharma; Kos Pharmaceuticals; Data
Scope; Astra Zeneca Pharmaceuticals; Astra-Zeneca-Canada; Schering-Plough Coorporation, Ltd; Sanofi-Aventis, Inc; First Horizon;
and GE Healthcare. All industrial funding for this trial was directed through the Department of Veterans Affairs. Additional
funding for this substudy was provided by grants to the Department of Veterans Affairs and Canadian Institutes of Health Research
from Astellas Pharma and Bristol-Myers-Squibb Medical Imaging. 相似文献
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Arianne C Lim Kitty WM Bloemenkamp Kees Boer Johannes J Duvekot Jan Jaap HM Erwich Tom HM Hasaart Pieter Hummel Ben WJ Mol Jos PM Offermans Charlotte M van Oirschot Job G Santema Hubertina CJ Scheepers Willem A Schöls Frank PHA Vandenbussche Maurice GAJ Wouters Hein W Bruinse 《BMC pregnancy and childbirth》2007,7(1):1-6
Background
Adequate vitamin D concentrations during pregnancy are necessary to neonatal calcium homeostasis, bone maturation and mineralization. The aim of study is to evaluate serum vitamin D concentrations in mothers and their newborns and effect of vitamin D deficiency on pregnancy outcomes.Methods
552 pregnant women were recruited from Tehran University educating hospitals in the winter of 2002. Maternal and cord blood samples were taken at delivery. The serum was assayed for 25-hydroxyvitamin D3, calcium, phosphorus and parathyroid hormone.Results
The prevalence of vitamin D deficiency in maternal and cord blood samples were 66.8% and 93.3%, respectively (<35 nmol/l). There was significant correlation between maternal and cord blood serum concentrations of vitamin D. In mothers with vitamin D deficiency, cord blood vitamin D concentrations was lower than those from normal mothers (P = .001). Also, a significant direct correlation was seen between maternal vitamin D intake and weight gain during pregnancy.Conclusion
Consideration to adequate calcium and vitamin D intake during pregnancy is essential. Furthermore, we think it is necessary to reconsider the recommendation for vitamin D supplementation for women during pregnancy. 相似文献8.
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Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献