Near-Infrared Spectroscopy and Imaging for Investigating Stroke Rehabilitation: Test-Retest Reliability and Review of the Literature

Strangman G, Goldstein R, Rauch SL, Stein J. Near-infrared spectroscopy and imaging for investigating stroke rehabilitation: test-retest reliability and review of the literature.ObjectivesTo review the use of near-infrared spectroscopy (NIRS) in stroke rehabilitation and to evaluate NIRS test-retest reliability within-session on a motor control task commonly used in neuroimaging of stroke recovery.DesignCohort study.SettingHospital-based research laboratory.ParticipantsNineteen healthy control subjects (age range, 22−55y).InterventionsSubjects performed 2 experimental runs of a finger-opposition task in a block-design paradigm (finger opposition alternated with a fixation rest period) while undergoing multichannel NIRS and physiologic monitoring.Main Outcome MeasureReliability coefficients (Pearson r) for oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) correlated amplitude modulations across measurement channels during individual blocks and block averages.ResultsCorrelations between single blocks (ie, 16-s slices of data) exhibited a correlation intercept of .33±.09 for O2Hb. This value was minimally decreased by increasing lag between compared blocks (slope, −.012; P=.019) but was substantially enhanced by averaging across blocks (within-run slope, .11; between-run slope, .044). Correlations using 64 seconds of data reached 0.6. Results for HHb were virtually identical.ConclusionsNIRS modulations were repeatable even when comparing very short segments of data. When averaging longer data segments, the test-retest correspondences compared favorably to neuroimaging using other modalities. This suggests that NIRS is a reliable tool for longitudinal stroke rehabilitation and recovery studies.