Comparing Arterial Virtual Non-Contrast Scans with Venous Virtual Non-Contrast Scans in Their Feasibility to Substitute True Non-Contrast Scans Using Detector-Based Spectral Computed Tomography Scanner رسالة ماجستير

Abstract

Introduction: Spectral Computed Tomography (CT) is one of the innovations in radiology that has helped reduce the patient’s dose and improve the image quality; one of the applications that can be done using spectral CT is the creation of Virtual Non-Contrast (VNC) images using material decomposition, these images can be created from any phase in contrast-enhanced scans. If VNC images closely resemble True Non-Contrast (TNC) images, TNC images can be replaced with VNC images and reduce the patient dose. Purpose: This study aims to compare VNC images created from the arterial phase (VNC-A) and the VNC images created from the venous phase (VNC-V) with the TNC images for the abdomen, to determine if either of them is similar to the TNC image enough to replace it. Methods: 141 abdominal CT scans, which were done in AL-Rahma clinic between July 2022 and October 2024 using a detector-based spectral CT scanner, were enrolled in the study; each scan had a non-enhanced phase, an arterial-enhanced phase, and a venous enhanced phase. A VNC image was reconstructed from both the venous phase and the arterial phase, and the images were compared by the Mean Attenuation (MA) and the Standard Deviation (SD) of the Regions Of Interest (ROI) that were placed in five different places across the abdomen, to show the difference between the images in term of the attenuation values and the image noise. V Results: The relation between the TNC with VNC-A images, and TNC with VNC-V images across all ROIs was significantly different, with TNC having higher mean MA values (46.36 for TNC in comparison to 39.87 for VNC-A and 34.66 for VNC-V in ROI (2)), and SD values (19.27 for TNC in comparison to 10.45 for VNC-A and 10.34 for VNC-V in ROI (5)) than both VNC image types. The Signal-to-Noise Ratio (SNR) was also higher in TNC than that in VNC-A and VNC-V. Conclusion: Neither VNC-A nor VNC-V were sufficient to replace TNC images without degrading the image quality and the diagnostic ability of the scan, due to significant differences in the attenuation numbers and the SNR