In Vitro Parameter Optimization of the Triangle—Bone, Iodine Contrast Media, and Metal Artifact Volume—in DECT

Introduction: Dual-energy computed tomography (DECT) reduces metal artifact volume (MAV) by calculating virtual monoenergetic computed tomography (VMCT) scans. Different energies influence densities of iodinated contrast media (iCM) and bone. This triangle—bone and iCM density and MAV—is mandatory for CT arthrography with joint-related metallic implants (JRMIs). We investigated the energy-related influence on different dilutions of iCM, MAV, and bone density in an experimental setting.

Material and Methods: A phantom was built with a titanium metal plate, a piece of bovine long bone, and probes (1 mL) of 0.9% saline solution and six different dilutions of iCM (400 mg/mL, 300 mg/mL, 200 mg/mL, 100 mg/mL, 50 mg/mL, and 25 mg/mL iodine content). All contents were embedded in 0.5% gelatin.

DECT was performed on a 64-slice CT scanner (Siemens, Sensation 64) with two sequential scans (80 keV and 140 keV) and calculated to VMCT (40, 50, 70, 100, 120, 140, and 190 keV).

MAV, iCM to bone contrast to noise ratio (iCM-b-CNR), and density were measured digitally for all probes. Optimized iCM-b-CNR, density differences, and reduction of MAV were correlated considering different VMCT energy levels.

Results: The iCM with iodine contents of 200, 300 and 400 mg/mL and titanium plate were on the upper border of measurable density (3,000 HU) at any energy level. Bone density decrease with rising energy levels was parallel to 100 mg/mL iodine content. The iCM-b-CNR was optimal at VMCT of 120 to 190 keV. MAV optimum was achieved with VCMT of 120 to 190 keV.

Conclusion: The phantom study suggests iCM with 200 mg/mL iodine content, VAM of 120 keV considering iCM-b-CNR and MAV, with regard to CT arthrography with JRMI.

No conflict of interest has been declared by the author(s).