Diffusion, utilisation and regional variations in the use of CT and MRI in Sweden.

To study the diffusion, access, use, and utilisation of Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) in Sweden a national survey was carried out by a written questionnaire mailed to all public and private hospitals and clinics in 1997. To get a survey of CT and MRI in other countries a request asking for number of units was sent to recognised authorities and individuals in selected countries. CT and MRI were introduced in Sweden in 1973 and 1984 respectively. The diffusion of CT and MRI in Sweden are amongst the highest in the world. Considering the small size of the country and the medical community (e.g. facilitating transparency in indications for use of CT and MRI) and the relatively homogeneous health care system (tax based finance system) the regional variations in access, use, and utilisation of CT and MRI were surprisingly large. For example: In 1996 the number of CT examinations per 100.000 inhabitants varied from 3.344 to 4.705 between the regions. The MRI examinations varied from 751 to 1.858. Some of the differences may be explained by demographic factors. Also, reimbursement policies by the county councils for CT and MRI examinations varied which gave different incentives for patient referrals. However, to explain most of the differences more research is needed. Factors like proportion of elderly amongst the populations in the regions and other socio-demographic factors, proportion of research orientation of examinations and national medical specialities, organisation of the health care, etc. may to a greater extent explain the differences.