Utility of skull radiographs in infants undergoing 3D head CT during evaluation for physical abuse

Background: Clinical practice guidelines recommend performing head CT and skull radiographs (SR) when evaluating infants for physical abuse. We compared the accuracy of 3-dimensional CT (3DCT) and SR for detecting skull fractures. Methods: We reviewed children <12 months evaluated for physical abuse undergoing 3DCT and SR between January 2017 and December 2018. 3DCT and SR images were blindly read by 2 radiologists. Interrater reliability (IRR) was calculated. Diagnostic accuracy was compared using McNemar's test. Results: 158 infants with a mean age of 5.0 months underwent 3DCT and SR. Consensus reading identified 46 fractures (29.1%) on 3DCT and 40 fractures (25.3%) on SR. IRR was higher for 3DCT (κ = 0.95) than for SR (=0.65). 11 fractures were identified on 3DCT but not SR. 5 fractures were identified on SR but not 3DCT. There was no difference in the diagnostic accuracy of 3DCT and SR (χ² = 1.56, p = 0.211). Conclusions: We found no difference in the accuracy of 3DCT and SR for detecting skull fractures in infants. Because 3DCT has better IRR and evaluates for both bony and intracranial injuries it is superior to SR. Omitting SRs may be acceptable if a 3DCT is performed, and would reduce radiation exposure without compromising diagnostic accuracy.