Technologies play an important role in medical diagnoses: from physical examination and results processing and sharing, to accessing patients’ health records, to the review of clinical histories. However, new technologies are acknowledged as a major cost driver in health systems (OECD, 2024[1]). This section presents data on the availability and use of three diagnostic imaging technologies: computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). CT and MRI examinations (exams) both show images of internal organs and tissues, while PET scans show other information and problems at the cellular level.
There is no general guideline or international benchmark regarding the ideal numbers of CT scanners, PET scanners or MRI units. Too few units may lead to access problems in terms of geographical proximity or waiting times, while too many may result in overuse of these costly diagnostic procedures, with little if any benefit for patients.
Availability of CT and PET scanners and MRI units has increased rapidly in most OECD countries over the past few decades. Japan had by far the highest number of CT scanners and MRI units, and the third highest number of PET scanners per capita. Australia has the next highest number of CT scanners; the United States the second highest numbers of MRI units and PET scanners; and Denmark the highest number of PET scanners per capita (Figure 9.10). The combined numbers of these three diagnostic technologies were also substantially higher than the OECD average in Greece, Korea, and Italy; and much lower than the average in Colombia, Costa Rica and Mexico.
Data on use of diagnostic scanners are available for 31 OECD countries. Taken together, use of CT, MRI and PET diagnostic exams was highest in Luxembourg, Korea, Austria, France and Portugal, all of which had a combined total of over 370 exams per 1 000 population in 2023 (Figure 9.11). Use of these three diagnostic exams was lowest in Costa Rica and Finland; as well as accession countries Romania and Bulgaria. There are large variations in the use of CT scanners and MRI units, not only across but also within countries – for example, in Norway, a recent analysis revealed nearly 50% geographical variation in use of outpatient diagnostic imaging exams for the musculoskeletal system, as well as for the thorax, abdomen, and blood vessels, in 2019 (Hofmann and Gransjøen, 2022[2]).
Looking at trends over time, the number of CT and MRI exams per 1 000 population has continued to grow in several countries, including Australia, Belgium, France, Germany, Korea and Latvia (Figure 9.12). Between 2013 and 2023, the number of CT exams more than doubled in Korea and increased by more than 50% in Australia and Latvia. Similarly, numbers of MRI exams more than doubled in Korea and Latvia, increased by around 70% in France, and rose steadily in Belgium and Germany.
Clinical guidelines on MRI and CT exams exist in OECD countries to promote appropriate imaging and to enhance patient safety by avoiding unnecessary procedures. Previous studies have assessed the appropriateness of CT and MRI exams by comparing them against national guidelines or specific imaging referral criteria. For instance, a recent retrospective analysis conducted in Sweden evaluated the appropriateness of 13 075 MRI and CT examinations using the European Society of Radiology’s guidance for appropriate imaging. The study found that 76% of MRI exams and 63% of CT exams were classified as appropriate according to this guideline (Ståhlbrandt et al., 2023[3]).
