“Number needed to read”—How to facilitate clinical trials in MR-angiography
- نوع فایل : کتاب
- زبان : انگلیسی
- مؤلف : M. Voth & U. I. Attenberger & A. Luckscheiter & S. Haneder & T. Henzler & S. O. Schoenberg & C. Schwenke & H. J. Michaely
- چاپ و سال / کشور: 2010
Description
Purpose To evaluate the effect of the number of readers on the statistical results in peripheral MRA. Materials and methods 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. Results 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. Conclusion 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.
Eur Radiol (2011) 21:1034–1042 DOI 10.1007/s00330-010-1993-2 Received: 11 July 2010 / Revised: 30 August 2010 / Accepted: 29 September 2010 / Published online: 23 October 2010
