Effect of multi-phasic CTU on diagnostic confidence of radiologists. Are all three phases necessary?

Abstract

Background: The availability of multidetector CT at medical centers has led to the routine use of CT Urography (CTU) in imaging of the urinary tract. The number of phases of CTU generally varies between two and four, and because of the high radiation dose of CTU, the number of phases should be kept to a minimum. There are not enough data available on how radiologists use the multiphasic nature of CTU in the diagnostic process of urological conditions. The purpose of this study was to determine the subjectively experienced usefulness of different CTU phases in urinary tract evaluation by measuring the level of diagnostic confidence at each phase. Methods: consecutive CTU examinations performed between February 2021 and November 2021 were retrospectively reviewed. Thirty-nine patients who underwent CTU examination on a 32-slice CT scanner were included. The standard protocol for CTU consisted of the following: unenhanced phase, enhanced corticomedullary phase, and in a subset of cases, an adjunct 10-min delayed excretory phase. All images were reconstructed with multi-planar reconstruction in three planes: axial, coronal and sagittal. During the reading sessions, the images of each phase were assessed individually for the presence of urinary tract abnormalities and the diagnostic confidence was estimated using a graded scale. Evaluation for incidental finding were also done on unenhanced and enhanced phase. Statistical analysis was performed using paired-sample t test. The limit for significance was set at p = 0.05. Results: a significantly higher diagnostic confidence scores were obtained in the enhanced corticomedullary phase for urinary tract pathologies (P = 0.0001) and incidental findings (P < 0.0001) when comparing the unenhanced phase to enhanced corticomedullary phase. The diagnostic confidence scores obtained in the corticomedullary phase for urinary tract pathologies were also higher than excretory phase, but the difference was not statistically significant. Conclusion: the enhanced corticomedullary phase had a significantly higher effect on diagnostic confidence when compared to the unenhanced phase. The analysis suggests that a corticomedullary phase CTU may be sufficient as a problem-solving imaging tool of urinary tract, especially in patients where radiation burden is of concern.