The Impact Factor of Radiological Journals: Associations with Journal Content and Other Characteristics Over a Recent 12-Year Period.

RATIONALE AND OBJECTIVES: The aim of this study was to evaluate the trends in the impact factor (IF) of radiological journals over a recent 12-year period, including associations between IF and journal topic. MATERIALS AND METHODS: Journal Citation Reports (JCR) was used to identify all biomedical journals and all radiological journals (assigned a JCR category of "Radiology, Nuclear Medicine, & Medical Imaging"), along with journal IF, in 2003 and 2014. Radiological journals were manually classified by topic. Trends in median IF (mIF) were assessed. RESULTS: The number of radiological journals increased from 83 (2003) to 125 (2014) (all biomedical journals: 5907 to 8718, respectively). mIF of radiological journals increased from 1.42 (2003) to 1.75 (2014) (all biomedical journals: 0.93 to 1.46, respectively). The most common topic among new radiological journals was general (nonspecialized) radiology (8). Five new radiological journals in 2014 were in topics (cancer imaging and molecular imaging) having no journals in 2003. mIF of general radiological journals was 1.49. Topics having highest mIF were cardiac imaging (2.94), optics (2.86), molecular imaging (2.77), radiation oncology (2.60), and neuroradiology (2.25). Topics with lowest mIF were ultrasound (1.19) and interventional radiology (1.44). Topics with the largest increase in mIF were cardiac imaging (from 1.17 to 2.94) and neuroradiology (from 1.07 to 2.25). CONCLUSIONS: Radiological journals exhibited higher mIF than biomedical journals overall. Among radiological journals, subspecialty journals had highest mIF. While a considerable number of new radiological journals since 2003 were general radiology journals having relatively low IF, there were also new journal topics representing emerging areas of subspecialized radiological research.