Can virtual non-contrast imaging replace true non-contrast imaging in multiphase scanning of the neck region?

Abstract

Background Dual-energy computed tomography (DECT) is an advanced imaging method that enables reconstruction of virtual non-contrast (VNC) images from a contrast-enhanced acquisition. This has the potential to reduce radiation exposure by eliminating the need for a true non-contrast (TNC) phase. Purpose The purpose is to evaluate the feasibility of VNC images in the neck region. Materials and methods A total of 100 patients underwent a DECT scan as part of diagnostic workup of primary hyperparathyroidism. VNC images were reconstructed from 30 s (arterial) and 50 s (venous) post-contrast scans. Regions of interest (ROIs) were placed in thyroid tissue, lymph node, carotid artery, jugular vein, fat, and sternocleidomastoid muscle. Mean densities of all anatomical structures were compared between VNC and TNC images. Results For all anatomical structures except the thyroid gland, the difference in mean density between TNC and VNC images was less than 15 HU. The mean difference in density between TNC and VNC images of the thyroid was 53.2 HU (95% CI 46.8; 59.6, p = <0.001). Conclusion This study demonstrated an acceptable agreement in density between true non-contrast and virtual non-contrast images for most anatomical structures in the neck region. Therefore, VNC images may have the potential to replace TNC images in the neck. However, due to significant differences in CT density of thyroid tissue, true non-contrast imaging cannot be directly substituted by virtual non-contrast imaging when examining the thyroid and its surrounding tissue.

Virtual Non-Contrast versus True Native in Photon-Counting CT: Stability of Density of Upper Abdominal Organs and Vessels

“…Additionally, several studies have shown that DECT-derived VNC reconstructions cannot totally substitute TNC images. In the imaging of the neck, a significant variation in the density of the thyroid tissue has been demonstrated between VNC reconstructions and TNC [ 16 ]. In the detection of kidney stones, the accuracy of DECT-derived VNC reconstructions was also limited by the surrounding iodine-enhanced contrast [ 17 ].…”