Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany.
Eur Radiol. 2011 May;21(5):1034-42. doi: 10.1007/s00330-010-1993-2. Epub 2010 Oct 23.
To evaluate the effect of the number of readers on the statistical results in peripheral MRA.
40 patients with peripheral arterial occlusive disease were included as a sample dataset in this study, randomly separated into two matched groups with n = 20 patients (group 1--gadobutrol, group 2--gadoterate meglumine) who underwent a continuous table movement MRA of the peripheral vessels at 3 T. Image quality (IQ) of 17 vessel segments was evaluated by 5 independent readers. The effect of the number of readers on significance and statistical power was statistically analyzed.
Image quality in group 1 (gadobutrol) ranks significantly higher compared to group 2 (gadoterade meglumine) with a diagnostic IQ in 97% vs. 78% (p < 0.0001). For the diagnostic/non-diagnostic IQ assessment significance was reached with one reader 1/5 times (20%), with two readers in 4/10 (40%), with three readers in 6/10 (60%), with four readers in 4/5 (80%), with five readers in 1/1 (100%). Power considerations showed considerable gain when increasing the number of readers.
Increasing the number of readers in a diagnostic MRA-study can be used to achieve a higher power or to decrease the number of subjects included with maintained statistical validity.
评估在周围 MRA 中读者数量对统计结果的影响。
本研究纳入 40 例周围动脉闭塞性疾病患者作为样本数据集，随机分为两组，每组 20 例患者（组 1-钆布醇，组 2-钆特酸葡胺），在 3T 下进行连续表移 MRA 外周血管成像。5 位独立读者评估 17 个血管节段的图像质量（IQ）。统计分析了读者数量对显著性和统计功效的影响。
组 1（钆布醇）的图像质量明显高于组 2（钆特酸葡胺），诊断 IQ 为 97%对 78%（p < 0.0001）。对于诊断/非诊断 IQ 评估，一位读者有 1/5 次（20%）、两位读者有 4/10 次（40%）、三位读者有 6/10 次（60%）、四位读者有 4/5 次（80%）、五位读者有 1/1 次（100%）具有显著性。当增加读者数量时，功效考虑显示出相当大的增益。
在诊断性 MRA 研究中增加读者数量可以提高功效或减少纳入的受试者数量，同时保持统计有效性。
