A visual MRI atrophy rating scale for the amyotrophic lateral sclerosis-frontotemporal dementia continuum

Abstract

Our objective was to distinguish ALS, ALS-FTD and bvFTD via a novel visual MRI cortical atrophy scale that can be employed in a clinical setting. MRI images of 100 participants (33 ALS, 11 ALS-FTD, 22 bvFTD and 34 controls) were rated in four brain areas: orbitofrontal cortex, anterior temporal pole, anterior cingulate, and motor cortex. Areas were rated on a 5- point Likert scale by two raters blinded to the diagnosis. Results demonstrated that bvFTD patients showed the highest levels of atrophy across all regions, while ALS patients had the lowest atrophy scores. ALS-FTD patients have higher atrophy ratings compared to ALS patients for the motor cortex, anterior cingulate and anterior temporal lobe, with a statistical trend for the orbitofrontal cortex. ALS-FTD patients were not significantly different from bvFTD for any of the brain regions. These findings were confirmed in a post hoc VBM analysis of the same participants. Our study demonstrates that a simple visual MRI rating scale can reliably distinguish ALS, ALS-FTD and bvFTD atrophy patterns in a clinical setting. Motor cortex, anterior cingulate and anterior temporal atrophy emerged as good diagnostic markers for ALS-FTD. Employment of this MRI rating scale can complement clinical diagnostics of patients in the ALS-FTD continuum.

Key words::

• Visual atrophy rating scale
• MRI
• amyotrophic lateral sclerosis
• frontotemporal dementia

Acknowledgements

We are grateful to the patients and their families for their support of our research. This study was supported by Australian Research Council and National Health & Medical Research Council grants. MCK and JRH are supported through a NHMRC Program Grant. MH is supported by an Australian Research Council Research Fellowship.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.