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Sample Size Calculation for Clinical Trials Using Magnetic Resonance Imaging for the Quantitative Assessment of Carotid Atherosclerosis.
- Source :
-
Journal of Cardiovascular Magnetic Resonance (Taylor & Francis Ltd) . Dec2005, Vol. 7 Issue 5, p799-808. 10p. 3 Black and White Photographs, 4 Charts, 1 Graph. - Publication Year :
- 2005
-
Abstract
- Purpose. To provide sample size calculation for the quantitative assessment of carotid atherosclerotic plaque using non-invasive magnetic resonance imaging in multi-center clinical trials. Methods. As part of a broader double-blind randomized trial of an experimental pharmaceutical agent, 20 asymptomatic placebo-control subjects were recruited from 5 clinical sites for a multi-center study. Subjects had 4 scans in 13 weeks on GE 1.5 T scanners, using TOF, T1-⁄PD-⁄T2- and contrast-enhanced T1-weighted images. Measurement variability was assessed by comparing quantitative data from the index carotid artery over the four time points. The wall⁄outer wall (W⁄OW) ratio was calculated as wall volume divided by outer wall volume. The percent lipid-rich⁄necrotic core (%LR⁄NC) and calcification (%Ca) were measured as a proportion of the vessel wall. For %LR⁄NC and %Ca, only those subjects that exhibited LR⁄NC or Ca components were used in the analysis. Results. Measurement error was 5.8% for wall volume, 3.2% for W⁄OW ratio, 11.1% for %LR⁄NC volume and 18.6% for %Ca volume. Power analysis based on these values shows that a study with 14 participants in each group could detect a 5% change in W⁄OW ratio, 10% change in wall volume, and 20% change in %LR⁄NC volume (power = 80%, p < .05). The calculated measurement errors presume any true biological changes were negligible over the 3 months that subjects received placebo. Conclusion. In vivo MRI is capable of quantifying plaque volume and plaque composition, such as %lipid-rich/necrotic core and %calcification, in the clinical setting of a multi-center trial with low inter-scan variability. This study provides the basis for sample size calculation of future MRI trials. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10976647
- Volume :
- 7
- Issue :
- 5
- Database :
- Academic Search Index
- Journal :
- Journal of Cardiovascular Magnetic Resonance (Taylor & Francis Ltd)
- Publication Type :
- Academic Journal
- Accession number :
- 18970473
- Full Text :
- https://doi.org/10.1080/10976640500287703