TableĀ 2

Summary of key design decisions, associated methodological considerations and clinical implications

Design decisionsMethodological considerationsClinical implications
Defining a region of interestIs there a good evidence base for atrophy in the region?Dictates utility and interpretation in certain clinical populations
Should the region be rated in >1 imaging plane?Requires three-dimensional or multiple image acquisitions and increases time to perform rating
Is there an imaging landmark to allow consistent slice selection?Improves test-retest reliability
Displaying a region of interestIs the MR contrast appropriate and in common clinical use?Affects the appearance of atrophy and the sensitivity to artefacts
Is the appearance of the region badly affected by patient positioning?Difficult to rate certain regions or to reliably assess symmetry if the head is tilted
Defining scale incrementsHow much variation can reliably be captured?Truncated use of the scale may result in decreased diagnostic value
Is there a reliable cut-off between normal and abnormal scan appearance? Should the cut-off be adjusted for age?Affects clinical interpretation
Providing training materialHow is each scale increment best described and are there reference images available to demonstrate these features?Provides a useful framework for scoring
Are there expert raters available to provide training sets?Provides confidence in ratings and a means of audit
Validating the scaleWhat is the inter-rater/intra-rater reliability and how should it be measured?Determines suitability for use in clinical practice and comparison with other scores
Do the scores correlate with clinical measures or other measures of atrophy?Validates clinical relevance
Is there a diagnostic gold standard available for comparison?Provides validation of diagnostic value