Mark Mikkelsen1, Rachelle S Loo2, Nicolaas A J Puts1, Richard A E Edden1, Ashley D Harris3. 1. Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA. 2. Department of Radiology, University of Calgary, Calgary, AB, Canada; Child and Adolescent Imaging Research (CAIR) Program, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada. 3. Department of Radiology, University of Calgary, Calgary, AB, Canada; Child and Adolescent Imaging Research (CAIR) Program, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada. Electronic address: ashley.harris2@ucalgary.ca.
Abstract
BACKGROUND: The relationships between scan duration, signal-to-noise ratio (SNR) and sample size must be considered and understood to design optimal GABA-edited magnetic resonance spectroscopy (MRS) studies. NEW METHOD: Simulations investigated the effects of signal averaging on SNR, measurement error and group-level variance against a known ground truth. Relative root mean square errors (measurement error) and coefficients of variation (group-level variance) were calculated. GABA-edited data from 18 participants acquired from five voxels were used to examine the relationships between scan duration, SNR and quantitative outcomes in vivo. These relationships were then used to determine the sample sizes required to observe different effect sizes. RESULTS: In both simulated and in vivo data, SNR increased with the square root of the number of averages. Both measurement error and group-level variance were shown to follow an inverse-square-root function, indicating no significant impact of cumulative artifacts. Comparisons between the first two-thirds of the data and the full dataset showed no statistical difference in group-level variance. There was, however, some variability across the five voxels depending on SNR, which impacted the sample sizes needed to detect group differences in specific brain regions. COMPARISON WITH EXISTING METHODS: Typical scan durations can be reduced if taking into account a statistically acceptable amount of variance and the magnitudes of predicted effects. CONCLUSIONS: While scan duration in GABA-edited MRS has typically been considered in terms of SNR, it is more appropriate to think in terms of the amount of measurement error and group-level variance that provides sufficient statistical power.
BACKGROUND: The relationships between scan duration, signal-to-noise ratio (SNR) and sample size must be considered and understood to design optimal GABA-edited magnetic resonance spectroscopy (MRS) studies. NEW METHOD: Simulations investigated the effects of signal averaging on SNR, measurement error and group-level variance against a known ground truth. Relative root mean square errors (measurement error) and coefficients of variation (group-level variance) were calculated. GABA-edited data from 18 participants acquired from five voxels were used to examine the relationships between scan duration, SNR and quantitative outcomes in vivo. These relationships were then used to determine the sample sizes required to observe different effect sizes. RESULTS: In both simulated and in vivo data, SNR increased with the square root of the number of averages. Both measurement error and group-level variance were shown to follow an inverse-square-root function, indicating no significant impact of cumulative artifacts. Comparisons between the first two-thirds of the data and the full dataset showed no statistical difference in group-level variance. There was, however, some variability across the five voxels depending on SNR, which impacted the sample sizes needed to detect group differences in specific brain regions. COMPARISON WITH EXISTING METHODS: Typical scan durations can be reduced if taking into account a statistically acceptable amount of variance and the magnitudes of predicted effects. CONCLUSIONS: While scan duration in GABA-edited MRS has typically been considered in terms of SNR, it is more appropriate to think in terms of the amount of measurement error and group-level variance that provides sufficient statistical power.
Authors: Mark Mikkelsen; Peter B Barker; Pallab K Bhattacharyya; Maiken K Brix; Pieter F Buur; Kim M Cecil; Kimberly L Chan; David Y-T Chen; Alexander R Craven; Koen Cuypers; Michael Dacko; Niall W Duncan; Ulrike Dydak; David A Edmondson; Gabriele Ende; Lars Ersland; Fei Gao; Ian Greenhouse; Ashley D Harris; Naying He; Stefanie Heba; Nigel Hoggard; Tun-Wei Hsu; Jacobus F A Jansen; Alayar Kangarlu; Thomas Lange; R Marc Lebel; Yan Li; Chien-Yuan E Lin; Jy-Kang Liou; Jiing-Feng Lirng; Feng Liu; Ruoyun Ma; Celine Maes; Marta Moreno-Ortega; Scott O Murray; Sean Noah; Ralph Noeske; Michael D Noseworthy; Georg Oeltzschner; James J Prisciandaro; Nicolaas A J Puts; Timothy P L Roberts; Markus Sack; Napapon Sailasuta; Muhammad G Saleh; Michael-Paul Schallmo; Nicholas Simard; Stephan P Swinnen; Martin Tegenthoff; Peter Truong; Guangbin Wang; Iain D Wilkinson; Hans-Jörg Wittsack; Hongmin Xu; Fuhua Yan; Chencheng Zhang; Vadim Zipunnikov; Helge J Zöllner; Richard A E Edden Journal: Neuroimage Date: 2017-07-14 Impact factor: 6.556
Authors: Frederic Boy; C John Evans; Richard A E Edden; Andrew D Lawrence; Krish D Singh; Masud Husain; Petroc Sumner Journal: Biol Psychiatry Date: 2011-07-14 Impact factor: 13.382
Authors: Nicolaas A J Puts; Richard A E Edden; C John Evans; Francis McGlone; David J McGonigle Journal: J Neurosci Date: 2011-11-16 Impact factor: 6.167
Authors: C John Evans; Nicolaas A J Puts; Siân E Robson; Frederic Boy; David J McGonigle; Petroc Sumner; Krish D Singh; Richard A E Edden Journal: J Magn Reson Imaging Date: 2012-11-27 Impact factor: 4.813
Authors: Tamar Kolodny; Michael-Paul Schallmo; Jennifer Gerdts; Richard A E Edden; Raphael A Bernier; Scott O Murray Journal: Autism Res Date: 2020-04-16 Impact factor: 5.216
Authors: Muhammad G Saleh; Min Wang; Mark Mikkelsen; Steve C N Hui; Georg Oeltzschner; Jeff Boissoneault; Bethany Stennett; Richard A E Edden; Eric C Porges Journal: NMR Biomed Date: 2020-01-14 Impact factor: 4.044
Authors: Celine Maes; Koen Cuypers; Kirstin-Friederike Heise; Richard A E Edden; Jolien Gooijers; Stephan P Swinnen Journal: Neuroimage Date: 2021-02-16 Impact factor: 6.556
Authors: Sofie Tapper; Steve C N Hui; Muhammad G Saleh; Helge J Zöllner; Georg Oeltzschner; Jamie Near; Brian J Soher; Richard A E Edden Journal: Magn Reson Med Date: 2021-09-14 Impact factor: 4.668
Authors: Aimie L Peek; Andrew M Leaver; Sheryl Foster; Georg Oeltzschner; Nicolaas A Puts; Graham Galloway; Michele Sterling; Karl Ng; Kathryn Refshauge; Maria-Eliza R Aguila; Trudy Rebbeck Journal: J Pain Date: 2021-06-25 Impact factor: 5.820
Authors: Geetanjali Murari; Darren Ri-Sheng Liang; Aliya Ali; Frankie Chan; Mirjam Mulder-Heijstra; Nicolaas Paul L G Verhoeff; Nathan Herrmann; J Jean Chen; Linda Mah Journal: Cereb Cortex Commun Date: 2020-06-08
Authors: Yanez Lopez Maria; Anthony N Price; Nicolaas A J Puts; Emer J Hughes; Richard A E Edden; Grainne M McAlonan; Tomoki Arichi; Enrico De Vita Journal: Neuroimage Date: 2021-03-09 Impact factor: 6.556