Dear Sir,
Thank you for the opportunity to respond to the comments on our article [1]. As Dr Sabour pointed out in the Letter to the Editor, the correct method when evaluating reproducibility using intra-class correlation coefficient (ICC) in our study is to calculate ICC for single measurements and not for mean of measurements. We used ICC1 (single rater, absolute agreement; calculated as ICC (1,1) described by Shrout and Fleiss [2]).
As we used a method for testing repeatability for single measurements, we believe that our conclusion is valid, i.e., reproducibility for 2D phase-contrast magnetic resonance imaging (PC-MRI) measured flow and velocity parameters is overall quite low, but higher for middle cerebral artery than for posterior cerebral artery and anterior cerebral artery.
References
Correia de Verdier M, Wikstrom J (2016) Normal ranges and test-retest reproducibility of flow and velocity parameters in intracranial arteries measured with phase-contrast magnetic resonance imaging. Neuroradiology 58(5):521–531. doi:10.1007/s00234-016-1661-6
Shrout PE, Fleiss JL (1979) Intraclass correlations: uses in assessing rater reliability. Psychol Bull 86(2):420–428
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This comment refers to the article available at 10.1007/s00234-016-1717-7
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Correia de Verdier, M., Wikström, J. Response to Letter to the Editor: “Reproducibility of flow and velocity parameters in intracranial arteries measured with phase-contrast magnetic resonance imaging; a methodological issue”. Neuroradiology 58, 951 (2016). https://doi.org/10.1007/s00234-016-1719-5
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DOI: https://doi.org/10.1007/s00234-016-1719-5