Number needed to read-—How to facilitate clinical trials in MR-angiographyReport as inadecuate




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European Radiology

, Volume 21, Issue 5, pp 1034–1042

First Online: 23 October 2010Received: 11 July 2010Revised: 30 August 2010Accepted: 29 September 2010

Abstract

PurposeTo evaluate the effect of the number of readers on the statistical results in peripheral MRA.

Materials and methods40 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.

ResultsImage 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.

ConclusionIncreasing 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.

KeywordsMRA Comparison study Power analysis Vessel segments Statistical significance  Download fulltext PDF



Author: M. Voth - U. I. Attenberger - A. Luckscheiter - S. Haneder - T. Henzler - S. O. Schoenberg - C. Schwenke - H. J. Michae

Source: https://link.springer.com/







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