Document Detail

Measuring the heart in pulmonary arterial hypertension (PAH): implications for trial study size.
MedLine Citation:
PMID:  20027579     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To calculate the sample size for a theoretical pulmonary arterial hypertension (PAH) randomized controlled trial (RCT) by using cardiovascular magnetic resonance (CMR) imaging to determine the repeatability of measures between two scans. MATERIALS AND METHODS: Two same-day examinations from 10 PAH patients were analyzed manually and semiautomatically. Study size was calculated from the standard deviation (SD) of repeatability. Different approaches to right-ventricle (RV) mass were investigated, agreement between methods tested and interobserver reproducibility measured by Bland-Altman analysis to explore how the PAH heart might be best measured. RESULTS: Repeatability was good for almost all manually-measured indices but poor for semiautomated measurement of RV mass and left-ventricle (LV) end-diastolic volume (EDV). Thus, for an RCT (power, 80%; significance level, 5%) analyzing "outcome" indices (RVEDV, LVEDV, RV ejection fraction, and RV mass; anticipated change: 10 mL, 10 mL, 3%, and 10 g, respectively) manually, 34 patients are required compared to 78 if analysis is semiautomated. RV mass was repeatable if the interventricular septum was divided between ventricles or if wholly apportioned to the LV. Limits of agreement between manual and semiautomated analyses were unsatisfactory for RV measures and interobserver reproducibility was worse for semiautomated than manual analysis. CONCLUSION: Manual is more robust than semiautomated analysis and at present should be favored in RCTs in PAH as it leads to lower sample size requirements.
William M Bradlow; Marina L Hughes; Niall G Keenan; Chiara Bucciarelli-Ducci; Ravi Assomull; J Simon R Gibbs; Raad H Mohiaddin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of magnetic resonance imaging : JMRI     Volume:  31     ISSN:  1522-2586     ISO Abbreviation:  J Magn Reson Imaging     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2009-12-28     Completed Date:  2010-03-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9105850     Medline TA:  J Magn Reson Imaging     Country:  United States    
Other Details:
Languages:  eng     Pagination:  117-24     Citation Subset:  IM    
Copyright Information:
(c) 2009 Wiley-Liss, Inc.
Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, UK.
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MeSH Terms
Heart Ventricles / pathology*
Hypertension, Pulmonary / diagnosis*
Image Enhancement / methods
Image Interpretation, Computer-Assisted / methods*
Information Storage and Retrieval / methods*
Magnetic Resonance Imaging / methods*
Randomized Controlled Trials as Topic / methods
Reproducibility of Results
Sample Size
Sensitivity and Specificity

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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