- Among all seven available iterative metal artifact reduction (IMAR) presets, the IMARDental preset unexpectedly provided the strongest reduction of metal artifacts around total knee endoprostheses during ultra-high-resolution photon-counting CT angiography.
- IMARDental significantly improved objective artifact reduction and achieved the highest subjective diagnostic confidence for assessing the popliteal artery, while maintaining image noise comparable to all other reconstruction presets.
- The study demonstrates that IMAR preset selection should be task-based rather than anatomy-based, suggesting that the default "Extremity" preset is not necessarily optimal for vascular assessment adjacent to metallic implants.
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Figure 2. The seven available iterative metal artifact reduction (IMAR) presets have vastly different influence on the diagnostic assessability of the popliteal artery (red arrows) in ultra-high-resolution photon-counting CT angiography of the lower extremity.
Source:
Huflage H, Kunz AS, Wech T, et al. Comparison of Iterative Metal Artifact Reduction Presets In Ultra-high-resolution Photon-counting CT Angiography of Patients with Total Knee Endoprosthesis. Academic Radiology. 2026.
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Software | VB10 |
Scan area | Lower extremity CTA |
Scan mode | Quantum Plus |
Scan direction | Craniocaudal |
Tube voltage [kV] | 140 |
Effective mAs [mAs] | CARE keV |
IQ level | 64 |
Dose modulation | Active |
CTDIvol [mGy] | n.a. |
DLP [mGy·cm] | Median 892 (747–1010.5) |
Rotation time [s] | 1.0 |
Pitch | 1.0 |
Field of view [mm] | 200 |
Slice collimation [mm] | 120 × 0.2 |
Slice width [mm] | 0.8 |
Reconstruction increment [mm] | 0.8 |
Reconstruction kernel | Bv56 |
Iterative reconstruction | QIR 4 |
Virtual monoenergetic images | 55 keV |
Metal artifact reduction | IMAR off + Extremity, Hip, Pacemaker, Lung coils, Shoulder, Dental, Neuro coils presets |
Contrast agent | Imeron 400 mg I/mL |
Contrast volume | 90 mL |
Saline chaser | 30 mL |
Flow rate | 3.0 mL/s |
Bolus triggering | ROI in infrarenal aorta, 100 HU threshold, 18 s delay |
