An Evaluation of the Efficacy of Metal Artifact Reduction Reconstructions In Head and Neck CT Scans Using Virtual Monoenergetic Images Acquired with Dual-Energy CT
Abstract
Purpose
To evaluate the accuracy of Metal Artifact Reduction (MAR) reconstructions in Head and Neck scans using Virtual Monoenergetic Images (VMI) acquired with the Dual-Energy CT (DECT) technology Gemstone Spectral Imaging (GSI)
Methods
Using the GE Revolution ApexTM CT Scanner, three separate scanning protocols were applied to investigate image quality of GSI MAR reconstructed 120kVp-like images: i) single-energy CT at 120kVp, ii) DECT and 120kVp-like to Dose Match (DM), iii) DECT and 120kVp-like to Noise Match (NM). Clinical Head and Neck protocols were used to establish the associated scanning parameters for DM and NM. For each protocol, the Sun Nuclear Advanced Electron Density phantom was used to quantify the change in Hounsfield Units (HU) in metal using Aluminum (Al), Titanium (Ti), and Stainless Steel (SS) cylindrical inserts, as well as the MAR reconstructions of each metal. Furthermore, geometric distortion was assessed visually using the cross-sectional area of the GSI MAR reconstructed metal inserts, and image quality with Sun Nuclear’s IQPhanTM and RapidCHECKTM software.
Results
Across all scans, both image quality and HU were consistent and accurate; specifically, HU of the metals prior to MAR reconstruction varied by <1% for both Al and Ti and <2.8% for SS. Moreover, there proved to be <2mm of geometric distortion in the diameter of the metal inserts. Additionally, both DM and NM MAR reconstructions produced accurate results with RapidCHECKTM for spatial frequency (5.54 – 5.72 lp/mm; MTF 10%), and low contrast detection higher than 0.3%. DECT NM scans systematically produced comparable results, while requiring on average 10% less dose than DECT DM scans.
Conclusion
These findings indicate a potential in dose reduction for Head and Neck CT scans, including those benefiting from MAR reconstructions. Using VMI acquired with DECT, scans requiring less dose produce clinically equivalent results without compromising image quality or MAR performance.