A Novel Reconstruction Technique to Reduce Stair-Step Artifacts in Sequential Mode Coronary CT Angiography

Lukas Jakob Moser; Victor Mergen; Thomas Allmendinger; Robert Manka; Matthias Eberhard; Hatem Alkadhi

doi:10.1097/RLI.0000000000001066

A Novel Reconstruction Technique to Reduce Stair-Step Artifacts in Sequential Mode Coronary CT Angiography

Invest Radiol. 2024 Jan 30. doi: 10.1097/RLI.0000000000001066. Online ahead of print.

Authors

Lukas Jakob Moser¹, Victor Mergen, Thomas Allmendinger, Robert Manka, Matthias Eberhard, Hatem Alkadhi

Affiliation

¹ From the Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (L.J.M., V.M., R.M., M.E., H.A.); Siemens Healthineers AG, Forchheim, Germany (T.A.); and Department of Radiology, Spital Interlaken, Spitäler fmi AG, Unterseen, Switzerland (M.E.).

PMID: 38284879
DOI: 10.1097/RLI.0000000000001066

Abstract

Purpose: Prospective electrocardiography-triggering is one of the most commonly used cardiac computed tomography (CT) scan modes but can be susceptible to stair-step artifacts in the transition areas of an acquisition over multiple cardiac cycles. We evaluated a novel reconstruction algorithm to reduce the occurrence and severity of such artifacts in sequential coronary CT angiography.

Materials and methods: In this institutional review board-approved, retrospective study, 50 consecutive patients (16 females; mean age, 58.9 ± 15.2) were included who underwent coronary CT angiography on a dual-source photon-counting detector CT in the sequential ultra-high-resolution mode with a detector collimation of 120 × 0.2 mm. Each scan was reconstructed without (hereafter called standard reconstruction) and with the novel ZeeFree reconstruction algorithm, which aims to minimize stair-step artifacts. The presence and extent of stair-step artifacts were rated by 2 independent, blinded readers on a 4-point discrete visual scale. The relationship between the occurrences of artifacts was correlated with the average and variability of heart rate and with patient characteristics.

Results: A total of 504 coronary segments were included into the analyses. In standard reconstructions, reader 1 reported stair-step artifacts in 40/504 (7.9%) segments, from which 12/504 led to nondiagnostic image quality (2.4% of all segments). Reader 2 reported 56/504 (11.1%) stair-step artifacts, from which 11/504 lead to nondiagnostic image quality (2.2% of all segments). With the ZeeFree algorithm, 9/12 (75%) and 8/11 (73%) of the nondiagnostic segments improved to a diagnostic quality for readers 1 and 2, respectively. The ZeeFree reconstruction algorithm significantly reduced the frequency and extent of stair-step artifacts compared with standard reconstructions for both readers (P < 0.001, each). Heart rate variability and body mass index were significantly related to the occurrence of stair-step artifacts (P < 0.05).

Conclusions: Our study demonstrates the feasibility and effectiveness of a novel reconstruction algorithm leading to a significant reduction of stair-step artifacts and, hence, a reduction of coronary segments with a nondiagnostic image quality in sequential ultra-high-resolution coronary photon-counting detector CT angiography.