The abstract format of original articles: differences between imaging and non-imaging journals

Objectives: To compare the abstract structure in the 70 highest-rank imaging journals with that of the two highest-rank journals in each of 35 non-imaging biomedical categories, according to 2008 impact factors. Methods: We searched on MEDLINE for articles published in high-ranking imaging and non-imaging journals. Abstract format was considered as: IMRaD (Introduction, Methods, Results, and Discussion/conclusion); extended structured (ES), when including headings other than IMRaD; or narrative (without headings). Results: Abstracts of the 70 highest-rank imaging journals were: IMRaD, n=43 (61%); narrative, n=27 (39%); ES, n=0. Abstracts of the 70 highest-rank non-imaging journals were: IMRaD, n=26 (37%); narrative, n=35 (50%); ES, n=9 (13%) (p=0.001). Additional headings were: study design, n=7; measurements, n=7; context/setting, n=4; interventions, n=2; rationale, n=1; level of evidence, n=1; clinical relevance, n=1. Study design was declared in 12/23 abstracts (57%) and 21/23 (91%) article bodies in Radiology, 6/21 (29%) and 10/21 (48%) in Investigative Radiology, 11/24 (46%) and 18/24 (75%) in European Radiology, and 12/30 (40%) and 23/30 (77%) in American Journal of Roentgenology, respectively. Conclusions: Although about 60% of imaging journals adhere to IMRaD format, 13% of non-imaging journals requires additional headings; ES abstracts may assist readers in selecting full articles to be read.