European Multicentre Study on Recurrent Imaging Practice in Computed Tomography

The study aims to compare recurrent CT imaging practices across multiple centres in Europe using incidence and prevalence metrics, and to test the feasibility of establishing a new benchmarking tool for recurrent imaging practice across facilities.

Data of CT exposure were collected in 31 facilities from 18 European countries. The incidence proportion in a single year (I  100; 1), cumulative incidence over 3 consecutive years (I  100; 3), and 3-year prevalence proportion (P  100; 3) of patients with cumulative effective dose (CED) ≥ 100 mSv were calculated, and statistical analyses performed to correlate them with other relevant indicators. The reference year for data collection was 2023, and the 3-year period covered 2022-2024.

The database included 711,749 patients in the reference year who underwent 1,658,246 CT exams, with an average number of 1.5 ± 0.6 CT exams per patient in the reference year and 2.4 ± 0.6 exams per patient in three years. Across facilities, I  100; 1 ranged from 0 to 2.9%, I  100; 3 from 0 to 8.6%, and P  100; 3 ranged from 0% to 4.4%. Strong linear correlation was found between the 3rd quartile values of yearly CED and I  100; 1. Multiple linear relationship was identified between I  100; 3, 3rd quartile of yearly CED and percentage of recurrent patients. The facilities' 3rd quartiles of yearly CED varied between 7.5 and 29.5 mSv, and the 75th percentile of their distribution was 17.6 mSv, which are lower than in previous studies.

Incidence proportion is recommended as the primary metric for future studies assessing recurrent imaging, since prevalence indexes substantially underestimate the rates of recurrent imaging. The 75th percentile of distribution of 3rd quartiles of yearly CED is a reasonable benchmark for facilities to trigger optimisation. Investigating the underlying factors and addressing high recurrent rates can contribute to enhanced patient care.