Prescription practices of diagnostic imaging in dementia: a survey of 47 Alzheimer's Centres in Northern Italy

Background: To date, there are no data at the national or European level on the prescription practices of imaging (CT, MR, and SPET) in the diagnosis of cognitively impaired elderly patients.

Methods: We addressed prescription practices of diagnostic imaging in 47 Alzheimer's Centres in Northern Italy, with an ad-hoc questionnaire.

Results: The use of imaging in new cases was relatively intensive: 62% of the Alzheimer's Centres prescribed CT to more than 95% of cases, 24% prescribed MR to more than 33% of cases, and 33% prescribed SPET to more than 5% of cases. A minority of Alzheimer's Centres (n = 3, 6%) prescribed imaging to less than 100% of new cases. The association between onsite scanner availability and frequency of prescription increased from CT (Odds ratio (OR) = 1.8) through MR (OR = 2.4) to SPET (OR = 4.6), although only the latter was significant (95% confidence interval (CI) 1.2-17.7, p = 0.003). Patient-related factors (age, severity of cognitive impairment, and clinical suspicion of cerebrovascular disease) influenced prescription of structural imaging in 30-53% of Alzheimer's Centres and organizational factors (onsite scanner availability, and waiting list) in a similar proportion (32 and 43% respectively).

Conclusions: Organizational factors play a relevant role in the prescription of imaging exams in patients with cognitive impairment and, at least for CT, the perceived diagnostic added value is rather low, suggesting a high degree of uncertainty in the clinical use of imaging techniques.