Repeatability of Motor and Working-Memory Tasks in Healthy Older Volunteers: Assessment at Functional MR Imaging
Abstract
PURPOSE: To prospectively determine the repeatability of functional magnetic resonance (MR) imaging brain activation tasks in a group of healthy older male volunteers.
MATERIALS AND METHODS: Local research ethics committee approval and informed consent were obtained. Sixteen men with a mean age of 69 years ± 3 (standard deviation) performed finger-tapping and N-back (number of screens back) working-memory tasks. Each subject underwent MR imaging three times in weekly intervals. Within-subject task repeatability was analyzed in terms of the number of voxels classified as activated (activation extent), the mean activation amplitude, and (for finger tapping) the center of the mass of the activated region. A repeatability index was calculated to compare test-retest repeatability between subjects and between functional MR imaging tasks. Within-session, between-session, and between-subject variability was assessed by using analysis of variance testing of activation amplitude and extent.
RESULTS: Nine of the 16 subjects generated useful data at all three MR imaging–functional task sessions. At single-subject, single-session analysis, cortical activation was identified in most subjects and at most sessions. The centers of the masses of motor cortex activation were highly reproducible (within 3 mm). Patterns of activation were qualitatively repeatable, but there was substantial variability in the amplitudes and extents of activated regions. Within-session coefficients of variation (CVs) for left- versus right-hand and right- versus left-hand finger tapping were, respectively, 65% and 43% for activation amplitude and 75% and 121% for activation extent. The between-session CVs for activation amplitude were similar to the within-session values, whereas between-session CVs for activation extent were much greater than within-session values, up to 206%.
CONCLUSION: The generally poor quantitative task repeatability highlights the need for further methodologic developments before much reliance can be placed on functional MR imaging results of single-session experiments.
© RSNA, 2004
References
- 1 Mattay VS, Frank JA, Santha AK, et al. Whole-brain functional mapping with isotropic MR imaging. Radiology 1996; 201:399-404.
- 2 Moser E, Teichtmeister C, Diemling M. Reproducibility and postprocessing of gradient-echo functional MRI to improve localisation of brain activity in the human visual cortex. Magn Reson Imaging 1996; 14:567-579.
- 3 Rombouts SA, Barkhof F, Hoogenraad FG, Sprenger M, Scheltens P. Within-subject reproducibility of visual activation patterns with functional magnetic resonance imaging using multisection echo planar imaging. Magn Reson Imaging 1998; 16:105-113.
- 4 Cohen MS, DuBois RM. Stability, repeatability, and the expression of signal magnitude in functional magnetic resonance imaging. J Magn Reson Imaging 1999; 10:33-40.
- 5 McGonigle DJ, Howseman AM, Athwal BS, Friston KJ, Frackowiak RS, Holmes AP. Variability in functional MR imaging: an examination of intersession differences. Neuroimage 2000; 11:708-734.
- 6 Miki A, Raz J, van Erp TG, Liu CS, Haselgrove JC, Liu GT. Reproducibility of visual activation in functional MR imaging and effects of postprocessing. AJNR Am J Neuroradiol 2000; 21:910-915.
- 7 Waldvogel D, van Gelderen P, Immisch I, Pfeiffer C, Hallett M. The variability of serial functional MR imaging data: correlation between a visual and a motor task. Neuroreport 2000; 11:3843-3847.
- 8 Raven J, Raven JC, Court JH. Manual for Raven’s progressive matrices and vocabulary scales Section 3, The standard progressive matrices. Oxford, England: Oxford Psychologists Press, 1998.
- 9 Casey BJ, Cohen JD, O’Craven K, et al. Reproducibility of fMRI results across four institutions using a spatial working memory task. Neuroimage 1998; 8:249-261.
- 10 Genovese CR, Noll DC, Eddy WF. Estimating test-retest reliability in functional MR imaging. I. Statistical methodology. Magn Reson Med 1997; 38:497-507.
- 11 Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 1:307-310.
- 12 Kato H, Izumiyama M, Izumiyama K, Takahashi A, Itoyama Y. Silent cerebral microbleeds on T2*-weighted MRI: correlation with stroke subtype, stroke recurrence, and leukoaraiosis. Stroke 2002; 33:1536-1540.
- 13 Bland JM, Altman DG. Measuring agreement in method comparison studies. Stat Methods Med Res 1999; 8:135-160.
- 14 Specht K, Willmes K, Shah NJ, Jäncke L. Assessment of reliability in functional imaging studies. J Magn Reson Imaging 2003; 17:463-471.
- 15 Noll DC, Genovese CR, Nystrom LE, et al. Estimating test-retest reliability in functional MR imaging. II. Application to motor and cognitive activation studies. Magn Reson Med 1997; 38:508-517.
- 16 Machielsen WC, Rombouts SA, Barkhof F, Scheltens P, Witter MP. FMRI of visual encoding: reproducibility of activation. Hum Brain Mapp 2000; 9:156-164.
- 17 Manoach DS, Halpern EF, Kramer TS, et al. Test-retest reliability of a functional MRI working memory paradigm in normal and schizophrenic subjects. Am J Psychiatry 2001; 158:955-958.
- 18 Miller MB, van Horn JD, Wolford GL, et al. Extensive individual differences in brain activations associated with episodic retrieval are reliable over time. J Cogn Neurosci 2002; 14:1200-1214.
- 19 Tegeler C, Strother SC, Anderson JR, Kim SG. Reproducibility of BOLD-based functional MRI obtained at 4 T. Hum Brain Mapp 1999; 7:267-283.
