Low tube voltage increases the diagnostic performance of dual-energy computed tomography in patients with acute appendicitis

Abstract

PURPOSE We aimed to assess the utility of dual-energy computed tomography (DECT) imaging in diagnosing acute appendicitis (AA) with density measurements of the appendix vermiformis. METHODS A total of 210 consecutive patients presenting with acute abdominal pain were scanned using DECT between January and October 2016. Twenty-six patients had pathologically confirmed AA, while 30 had normal appendices. Appendiceal densities were measured in the true axial section of the appendix vermiformis at 80 kVp, 140 kVp, virtual noncontrast, iodine overlay, mixed, and monoenergetic (40, 50, 60, 70, 80, 90, 100 keV) images. RESULTS Comparison of the appendix at different kVp and keV energy levels, virtual noncontrast, iodine overlay, and mixed images yielded significant differences between patients with appendicitis and those with a normal appendix (P < 0.001 for all). Receiver operating characteristic (ROC) curve analysis revealed that the 80 kVp image set yielded the best diagnostic performance among all image sets (area under the ROC curve [AUC], 0.996; P < 0.001), while 70 keV images yielded the highest diagnostic performance among the virtual monoenergetic image sets (AUC, 0.958; P < 0.001). Inter-rater agreement was good at 80 kVp images (intraclass correlation coefficient [ICC], 0.78, P < 0.001). CONCLUSION Evaluation of DECT image reconstructions suggested that low tube voltage with 80 kVp demonstrated accurate diagnostic performance for AA. This finding suggests that low kVp CT may be useful for diagnosing AA with reduced patient radiation exposure.