[Diagnostic imaging in dementia evaluation]

The aim of the study was to evaluate the changes in diagnoses and treatment by structural scanning in dementia evaluation.

336 elderly, consecutively evaluated patients from two university memory clinics (mean age 75 y, mean MMSE 21.7), were retrospectively diagnosed without and with inclusion of scan results. These results were compared to prospective data obtained from 137 patients scanned as part of a population based study (The Odense Study, mean age 78.5, mean MMSE 23.3). CT and MRI were performed in 93% and 7% of the patients, respectively.

Potentially reversible structural pathology was found in 3.5% of the memory clinic patients, and in 2% of the population based patients. By applying international diagnostic criteria and treatment recommendations to the retrospective memory clinic data, it was found that adding a structural scan changed diagnoses and treatment in 37% and 33% of the patients, primarily due to identification of cerebrovascular disease (CVD) in patients with no clinical signs or symptoms of CVD. In comparison, the change in diagnosis found in the prospective population data was lower (15%). It was not possible to identify a group of patients that would not benefit from scanning.

Our data support recent guidelines that suggest CT scan as a routine investigation in dementia evaluation.