The diagnostic performance of ultra-low-dose 320-row detector CT with different reconstruction algorithms on limb joint fractures in the emergency department.

Background: The aim of the study was to evaluate whether ultra-low-dose computed tomography (ULD-CT) could replace conventional-dose CT (CD-CT) for diagnosis of acute wrist, ankle, knee, and shoulder fractures in emergency departments (ED).

Methods: We developed CD-CT and ULD-CT scanning schemes for the various joints of the four limbs and scanned emergency patients prospectively. When performing CD-CT, a conventional bone reconstruction algorithm was used, while ULD-CT used both soft tissue and bone algorithms. A five-point scale was used to evaluate whether ULD-CT image quality affected surgical planning. The image quality and diagnostic performance of different types of scanned and reconstructed images for diagnosing fractures were evaluated and compared. Effective radiation dose of each group was calculated.

Results: Our study included 56 normal cases and 185 fracture cases. The combination of bone and soft tissue algorithms on ULD-CT can improve diagnostic performance, such that on ULD-CT, the sensitivity improved from 96.7% to 98.9%, specificity from 98.2% to 100%, positive predictive value from 99.4% to 100%, negative predictive value from 90.2% to 96.6% and diagnostic accuracy ranged from 97.5% to 99.1%. There were no statistically significant differences between ULD-CT and CD-CT on diagnostic performance (p values, 0.40-1.00). The radiation doses for ULD-CT protocols were only 3.0-7.7% of those for CD-CT protocols (all p < 0.01).

Conclusions: In the emergency department, the 320-row detector ULD-CT could replace CD-CT in the diagnosis of limb joint fractures. The combination of bone algorithm with soft tissue algorithm reconstruction can further improve the image quality and diagnostic performance.