CT and MRI imaging in Sweden: retrospective appropriateness analysis of large referral samples.

Objectives: The numbers of computed tomography (CT) and magnetic resonance imaging (MRI) examinations per capita continue to increase in Sweden and in other parts of Europe. The appropriateness of CT and MRI examinations was audited using established European appropriateness criteria. Alternative modalities were also explored. The results were compared with those of a previous study performed in Sweden.

Methods: A semi-automatic retrospective evaluation of referrals from examinations performed in four healthcare regions using the European appropriateness criteria in ESR iGuide was undertaken. The clinical indications from a total of 13,075 referrals were assessed against these criteria. The ESR iGuide was used to identify alternative modalities resulting in a higher degree of appropriateness. A qualitative comparison with re-evaluated results from the previous study was made.

Results: The appropriateness was higher for MRI examinations than for CT examinations with procedures classed as usually appropriate for 76% and 63% of the examinations, respectively. The degree of appropriateness for CT was higher for referrals from hospitals compared to those from primary care centres. The opposite was found for MRI examinations. The alternative modalities that would result in higher appropriateness included all main imaging modalities. The result for CT did not show improvement compared with the former study.

Conclusions: A high proportion of both CT and MRI examinations were inappropriate. The study indicates that 37% of CT examinations and 24% of MRI examinations were inappropriate and that the appropriateness for CT has not improved in the last 15 years.

Critical Relevance Statement: A high proportion of CT and MRI examinations in this retrospective study using evidence-based referral guidelines were inappropriate.

Key Points: ∙ A high proportion of CT and MRI examinations were inappropriate. ∙ The CT referrals from general practitioners were less appropriate that those from hospital specialists. ∙ The MRI referrals from hospital specialists were less appropriate that those from general practitioners. ∙ Adherence to radiological appropriateness guidelines may improve the appropriateness of conducted examinations.