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Dentate nuclei T2 relaxometry is a reliable neuroimaging marker in Friedreich's ataxia

Authors

  • C. Bonilha da Silva,

    1. Department of Neurology and Neuroimaging Laboratory, Faculty of Medicine, University of Campinas – UNICAMP, Campinas, SP, Brazil
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  • F. P. G. Bergo,

    1. Department of Neurology and Neuroimaging Laboratory, Faculty of Medicine, University of Campinas – UNICAMP, Campinas, SP, Brazil
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  • A. D'Abreu,

    1. Department of Neurology and Neuroimaging Laboratory, Faculty of Medicine, University of Campinas – UNICAMP, Campinas, SP, Brazil
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  • F. Cendes,

    1. Department of Neurology and Neuroimaging Laboratory, Faculty of Medicine, University of Campinas – UNICAMP, Campinas, SP, Brazil
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  • I. Lopes-Cendes,

    1. Department of Medical Genetics, Faculty of Medicine, University of Campinas – UNICAMP, Campinas, SP, Brazil
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  • M. C. França Jr

    Corresponding author
    1. Department of Neurology and Neuroimaging Laboratory, Faculty of Medicine, University of Campinas – UNICAMP, Campinas, SP, Brazil
    • Correspondence: M. C. França Junior, MD, PhD, Department of Neurology, University of Campinas – UNICAMP, Rua Tessália Vieira de Camargo, 126 Cidade Universitaria ‘Zeferino Vaz’, Campinas 13083-887, SP, Brazil (tel.: +55 19 3521 9217; fax: +55 19 3521 7933; e-mail: mcfrancajr@uol.com.br).

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Abstract

Background and purpose

In Friedreich's ataxia (FRDA), frataxin deficiency results in iron redistribution in the dentate nuclei (DNC). Clusters of iron cause inhomogeneities in a magnetic field and result in a reduction in T2 relaxation time (T2).

Methods

T2 was prospectively evaluated in DNC, putamen, substantia nigra (SN), cerebellar white matter (CWM) and caudate and the correlation with clinical parameters was investigated. Thirty-five patients (range 9–51 years) and 44 controls (12–49 years) underwent T2 multi-echo sequence in a 3T scanner. Twenty-three patients (12–50 years) and 19 controls (14–49 years) were reassessed after 1 year. T2 was evaluated using specialized software (Aftervoxel) and severity of disease was quantified with the Friedreich Ataxia Rating Scale (FARS).

Results

T2 of both DNC was significantly shorter in the FRDA group at baseline (right, 58.6 ± 8.3 ms vs. 63.7 ± 8.1 ms, P = 0.013; left, 56.7 ± 7.7 ms vs. 62.6 ± 6.8 ms, P = 0.001). No significant difference was found between groups regarding the SN, putamen, CWM and caudate T2. DNC T2 values correlated with age, FARS total score and FARS III subscore on both sides. Prospectively, there was a significant reduction of T2 in FRDA patients in right and left DNC (P = 0.001 and 0.009) but not in other structures. Amongst controls, none of the regions significantly changed after 1 year. DNC T2 change over time correlated with GAA expansions and clinical deterioration (expressed by a change in FARS scores).

Conclusions

DNC T2 values are abnormal in FRDA, progress over time and correlate with ataxia severity. These results strongly suggest that DNC relaxometry can be a useful neuroimaging marker in FRDA.

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