Side-by-side evaluation of virtual non-contrast and post-contrast images improves detection of clinically significant urolithiasis on single-phase split bolus dual-energy CT urography

Abstract

Objectives: Studies show insufficient sensitivity of virtual non-contrast (VNC) reconstructions for stone detection in dual-energy CT urography (DE-CTU). The aim of this study was to investigate if side-by-side-evaluation of both VNC and post-contrast images could increase the sensitivity of single-phase split bolus DE-CTU. Methods: Consecutive patients with haematuria who underwent split bolus DE-CTU on the same dual-source DE-CT scanner were retrospectively enrolled in the study. Intravenous furosemide and oral hydration were employed. Two readers, independently and then jointly in two separate sessions, recorded the location and the longest axial stone diameter on three randomised sets of images: separate VNC and post-contrast images, and side-by-side-reconstructions. True non-contrast (TNC) images served as the standard of reference. Results: A total of 83 urinary stones were detected on TNC images. Independent reader side-by-side-evaluation of VNC and post-contrast images yielded higher stone detection sensitivity (76 and 84%, respectively) compared to evaluation of only VNC (71 and 81%, respectively) or post-contrast images (64 and 80%, respectively). The sensitivity of joint reader evaluation of side-by-side-images reached almost 86% and was not significantly different from TNC images (p = 0.77). All stones larger than 3 mm were correctly detected by side-by-side-evaluation. Dose reduction of 55% could be achieved by omitting TNC scans. Conclusion: Side-by-side-VNC and post-contrast image evaluation enable detection of clinically significant urolithiasis on single-phase split bolus DE-CTU with significant dose reduction. Advances in knowledge: This study shows that single-phase DE-CTU is feasible if VNC imaging is simultaneously utilised with post-contrast images.

Abdominal virtual non-contrast images derived from energy spectrum CT to evaluate chemotherapy-related fatty liver disease

“…In addition, two experienced abdominal radiologists performed a subjective assessment of CRFLD on the TNC and three types of VNC image and had consistent diagnostic confidence between the two types of images. This result was expected, since the VNC technique is based on a multimaterial decomposition algorithm that removes iodine from the enhancement contrast to resemble TNC images (21)(22)(23). Additionally, similar to other studies (23,24,32), our study demonstrated that VNC imaging could reduce the radiation dose by approximately 25.0%.…”

“…It does this by using technology that can accomplish iodine removal and the subsequent addition of blood after image acquisition through the use of postprocessing material separation techniques (20). Therefore, VNC imaging can serve as an appropriate substitute for true non-contrast (TNC) imaging, reducing the scan time and radiation dose required (21)(22)(23).…”

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

“…In DECT, the potential of VNC in comparison to TNC is well examined, indicating that VNC can substitute TNC in several specific cases. However, in DECT, the use of VNC to detect fatty liver tissue [ 25 , 26 ] to differentiate adrenal adenomas from adrenal metastases [ 27 ], to detect urolithiasis [ 28 , 29 ] and to discriminate intraperitoneal haematoma [ 30 ] has been described previously. Despite these promising findings, pitfalls of VNC in DECT have been described.…”

A retrospective survey to establish institutional diagnostic reference levels for CT urography examinations based on clinical indications: preliminary results

“…Other studies provided data regarding single-, five-, and sixphase protocols [37]. Furthermore, in another study with a dual-energy multi-detector CT scanner, a dose reduction of up to 55% was reported when omitting the actual unenhanced scans with the aid of virtual unenhanced reconstruction techniques [45].…”