Translating state-of-the-art brain magnetic resonance imaging (MRI) techniques into clinical practice: multimodal MRI differentiates dementia subtypes in a traditional clinical setting

Abstract

Background: This study sought to validate the clinical utility of multimodal magnetic resonance imaging (MRI) techniques in the assessment of neurodegenerative disorders. We intended to demonstrate that advanced neuroimaging techniques commonly used in research can effectively be employed in clinical practice to accurately differentiate heathy aging and dementia subtypes.

Methods: Twenty patients with dementia of the Alzheimer's type (DAT) and 18 patients with Parkinson's disease dementia (PDD) were identified using gold-standard techniques. Twenty-three healthy, age and sex matched control participants were also recruited. All participants underwent multimodal MRI including T1 structural, diffusion tensor imaging (DTI), arterial spin labeling (ASL), and magnetic resonance spectroscopy (MRS). MRI modalities were evaluated by trained neuroimaging readers and were separately assessed using cross-validated, iterative discriminant function analyses with subsequent feature reduction techniques. In this way, each modality was evaluated for its ability to differentiate patients with dementia from healthy controls as well as to differentiate dementia subtypes.

Results: Following individual and group feature reduction, each of the multimodal MRI metrics except MRS successfully differentiated healthy aging from dementia and also demonstrated distinct dementia subtypes. Using the following ten metrics, excellent separation (95.5% accuracy, 92.3% sensitivity; 100.0% specificity) was achieved between healthy aging and neurodegenerative conditions: volume of the left frontal pole, left occipital pole, right posterior superior temporal gyrus, left posterior cingulate gyrus, right planum temporale; perfusion of the left hippocampus and left occipital lobe; fractional anisotropy (FA) of the forceps major and bilateral anterior thalamic radiation. Using volume of the left frontal pole, right posterior superior temporal gyrus, left posterior cingulate gyrus, perfusion of the left hippocampus and left occipital lobe; FA of the forceps major and bilateral anterior thalamic radiation, neurodegenerative subtypes were accurately differentiated as well (87.8% accuracy, 95.2% sensitivity; 85.0% specificity).

Conclusions: Regional volumetrics, DTI metrics, and ASL successfully differentiated dementia patients from controls with sufficient sensitivity to differentiate dementia subtypes. Similarly, feature reduction results suggest that advanced analyses can meaningfully identify brain regions with the most positive predictive value and discriminant validity. Together, these advanced neuroimaging techniques can contribute significantly to diagnosis and treatment planning for individual patients.

Keywords: Alzheimer’s; Magnetic resonance imaging (MRI); Parkinson’s; dementia; neurodegenerative.

Conflict of interest statement

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/qims-20-1355). Author SEJ, MD is the owner of Synaptec Network, an MRI software analytics company. Authors SB and TK, PhD. are both part-time employees of Synaptec Network. The other authors have no conflicts of interest to declare.

2021 Quantitative Imaging in Medicine and Surgery. All rights reserved.

Figures

Figure 1

Regions driving visual differentiation of neurodegenerative conditions. Comparison of the T1-weighted structural MR images visually inspected by trained raters attempting to differentiate patients with neurodegenerative disorders from healthy aging. Hippocampal atrophy, basal ganglia atrophy/deformation and disproportionate general atrophy were used to guide group classification. Red circles denote areas of comparison between groups by trained raters.

Figure 2

Regions yielding successful group classification. Figures showing the significant regions of interest which predicted group classification using all MR modalities to differentiate neurodegenerative disorders from healthy aging (top row); differentiate neurodegenerative disorders from healthy aging (middle row) using ASL (red/yellow; left), DTI (FA = green; MD = yellow; AD = purple; RD = pink; middle) and volumetrics (blue; right); differentiate the three group neurodegenerative subtypes from healthy aging (bottom row) using ASL (left), DTI (middle) and volumetrics (right). ASL, arterial spin labeling; DTI, diffusion tensor imaging; FA, fractional anisotropy; MD, mean diffusivity; AD, axial diffusivity; RD, radial diffusivity.