Incidental findings on cerebral MRI in twins: the Older Australian Twins Study
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Incidental findings on structural cerebral magnetic resonance imaging (MRI) are common in healthy subjects, and the prevalence increases with age. There is a paucity of data regarding incidental cerebral findings in twins. We examined brain MRI data acquired from community-dwelling older twins to determine the prevalence and concordance of incidental cerebral findings, as well as the associated clinical implications. Participants (n = 400) were drawn from the Older Australian Twins Study. T1-weighted and T2-weighted fluid-attenuated inversion recovery (FLAIR) cerebral MRI scans were systematically reviewed by a trained, blinded clinician. Incidental findings were recorded according to pre-determined categories, and the diagnosis confirmed by an experienced neuroradiologist. Periventricular and deep white matter hyperintensities (WMH) were scored visually. WMH heritability was calculated for those with the twin pair included in the study (n = 320 individuals; monozygotic (MZ) = 92 twin pairs, dizygotic (DZ) = 68 twin pairs). Excluding infarcts and WMH, a total of 47 (11.75%) incidental abnormalities were detected. The most common findings were hyperostosis frontalis interna (8 participants; 2%), meningiomas, (6 participants; 1.5%), and intracranial lipomas (5 participants; 1.25%). Only 3% of participants were referred for follow-up. Four twin pairs, all monozygotic, had lesions concordant with their twin. Periventricular WMH was moderately heritable (0.61, CI 0.43–0.75, p = 7.21E-08) and deep WMH highly heritable (0.80, CI 0.66–0.88, p = 1.76E-13). As in the general population, incidental findings on cerebral MRI in older twins are common, although concordance rates are low. Such findings can alter the clinical outcome of participants, and should be anticipated by researchers when designing trials involving cerebral imaging.
KeywordsIncidental findings Cerebral magnetic resonance imaging Older twins
Our sincere thanks to the twins who have donated their time to participate in the OATS, as well as the OATS Collaborative Research Team: New South Wales: Jocelyn Bowden, Suzy Forrester, Henry Brodaty, John Crawford, Tanya Duckworth, Kristan Kang, Amelia Assareh. Queensland: Natalie Garden, Nick Martin. Victoria: Christel Lemmon.
Compliance with ethical standards
The Older Australian Twins Study was supported by a National Health and Medical Research Council (NHMRC) / Australian Research Council (ARC) Strategic Award Grant of the Ageing Well, Ageing Productively Program (ID no. 401162). The Australian Twin Registry is supported by a Centre of Research Excellence Grant from the NHMRC administered by the University of Melbourne.
Conflict of interest
The authors declare that they have no conflicts of interest.
The Older Australian Twins Study obtained approval from the ethics committees of the Australian Twin Registry, University of New South Wales, University of Melbourne, Queensland Institute of Medical Research, University of Queensland, and the South Eastern Sydney & Illawarra Area Health Service.
Human and animal rights
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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