In plain English
Visual rating scales provide a standardised vocabulary for describing brain changes seen on Magnetic Resonance Imaging in dementia assessment. The most common scales in UK practice are MTA, GCA, Fazekas and Koedam. This page explains each in plain English.
Why visual rating scales matter
Brain imaging in dementia is largely interpreted by experienced eye, not by automated measurement. Visual rating scales give radiologists and clinicians a common language: a Fazekas grade 2 means the same thing in Edinburgh as it does in London, and comparisons between scans become meaningful. NICE NG97 supports the use of validated rating scales in dementia neuroradiology.
The MTA scale (Scheltens, 1992)
The Medial Temporal lobe Atrophy scale grades the volume of the hippocampus and the surrounding medial temporal structures. It is the most useful scale for Alzheimer's Disease assessment.
- MTA 0: no atrophy. Choroid fissure normal width, temporal horn normal width, hippocampus normal height.
- MTA 1: mild widening of the choroid fissure.
- MTA 2: clear widening of the choroid fissure with mild enlargement of the temporal horn and beginning hippocampal volume loss. Common at age 75 and over; consistent with Alzheimer's Disease in the right context.
- MTA 3: marked widening of the choroid fissure with moderate enlargement of the temporal horn and moderate hippocampal volume loss.
- MTA 4: severe hippocampal atrophy.
Age-adjusted norms: in adults under 75, MTA grade 2 or higher is suggestive of Alzheimer's Pathology; in those 75 and over, MTA 2 may be age-related.
The GCA scale (Pasquier, 1996)
The Global Cortical Atrophy scale grades cortical volume loss across the brain. Useful for distinguishing pathological atrophy from age-related change.
- GCA 0: no cortical atrophy.
- GCA 1: minimal sulcal widening; some opening of the cortical grooves.
- GCA 2: moderate atrophy with clear sulcal widening and some volume loss.
- GCA 3: marked global atrophy with "knife-edge" thinning of the gyri.
The Fazekas Scale (1987)
The Fazekas Scale grades white matter hyperintensities, which represent Small Vessel Disease.
- Fazekas 0: no white matter hyperintensities, or only punctate changes;
- Fazekas 1: a few small foci, separate;
- Fazekas 2: moderate; foci beginning to coalesce;
- Fazekas 3: extensive, confluent. Consistent with substantial Small Vessel Disease.
Fazekas grade 2 or higher in someone with cognitive impairment supports a vascular contribution.
The Koedam Scale (2011)
The Koedam Scale grades atrophy of the parietal lobe and posterior cingulate. Particularly useful in atypical Alzheimer's Disease and Posterior Cortical Atrophy.
- Koedam 0: closed sulci, no atrophy.
- Koedam 1: mild opening of parietal sulci.
- Koedam 2: marked widening of parietal sulci, opening of the cingulate sulcus.
- Koedam 3: severe atrophy of the parietal lobe and posterior cingulate.
The Wahlund Scale (2001)
An alternative scale for white matter changes, with separate scores for periventricular and deep white matter regions, plus basal ganglia and infratentorial regions. Used in some UK centres in place of Fazekas.
How the scales fit together
A typical dementia neuroradiology report describes:
- MTA: bilateral or asymmetric, with grades for each side;
- GCA: a single overall grade;
- Fazekas: a single grade for periventricular and deep white matter;
- Koedam: where parietal atrophy is relevant;
- Plus any specific findings (lacunes, infarcts, microbleeds, tumours, hydrocephalus).
Together these convey the structural picture in a way that supports the clinical formulation.
Where to find your scores
If you have a recent Magnetic Resonance Imaging report, look for MTA, GCA, Fazekas and Koedam in the body of the report. If the report describes findings qualitatively without these scales (for example, "mild medial temporal atrophy"), it is reasonable to ask whether explicit visual rating scale grades are available.
Frequently asked questions
What is a 'normal' MTA grade for my age?
Under 65: MTA 0. Age 65 to 75: MTA 0 or 1. Age 75 and over: MTA 1 to 2 may be age-related. Grades higher than these in the corresponding age group are suggestive of pathological atrophy.
Are higher scores always worse?
Within each scale, higher scores indicate more atrophy or more disease. Severity does not always correlate with the clinical picture; functional impact is what matters for diagnosis.
Why does my report not mention these scales?
Not all UK radiologists use formal visual rating scales. If your report describes findings qualitatively, ask your memory clinic whether explicit scale grades would help.
Can the same scan be re-rated?
Yes. A second radiologist can re-rate the same scan, and the results should agree within one grade for the standard scales. Re-rating can be useful where the original report is ambiguous.
Are visual scales used in CT?
Some are, but with less reliability than MRI. MRI is preferred for visual rating scale assessment.
References
- Scheltens P et al. JNNP 1992 (MTA scale).
- Pasquier F et al. Eur Neurol 1996 (GCA scale).
- Fazekas F et al. AJR 1987 (Fazekas Scale).
- Koedam ELGE et al. Eur Radiol 2011 (Koedam Scale).
- Wahlund LO et al. Stroke 2001 (Wahlund Scale).