TOPLINE

The "Dental" iterative metal artefact reduction (IMAR_dental) preset provided the highest objective and subjective image quality in ultra-high-resolution photon-counting CT angiography (PCCTA) of the lower leg among patients with total knee replacements, an observational study found.

METHODOLOGY

• Researchers retrospectively analysed data of 25 patients (mean age, 74 years; 12 women) with total knee replacements who underwent ultra-high-resolution PCCTA of the lower extremity between 2024 and 2025.
• The final dataset yielded 31 lower extremities for the analysis: 24 total knee arthroplasties, five modular rotating-hinge prostheses, and two unicompartmental knee prostheses.
• Each dataset was reconstructed without IMAR and with seven unique, vendor-specific IMAR presets (extremity, hip, pacemaker, lung coils, shoulder, dental, and neuro coils).
• Objective image quality was calculated using region-of-interest measurements inside the most pronounced hyperdense and hypodense artefacts, and image noise was measured in subcutaneous fat tissue.
• A total of 6076 pairs of reconstructions made with and without IMAR were compared and subjectively evaluated for popliteal artery assessability.

TAKEAWAY

• The IMAR_dental preset demonstrated the strongest reduction in hyperdense artefacts (median, 932.5 HU) compared with non-IMAR datasets (median, 4300.1 HU) and the other six IMAR presets (median, 3117.9-3377.1 HU; P < .001 for all).
• The IMAR_dental preset provided a superior reduction in hypodense artefacts (median, -97.5 HU) compared with the datasets reconstructed with other IMAR presets (median, -567.9 to -1523.3 HU; P ≤ .006 for all) and without IMAR (median, -3319.7 HU).
• Image noise was comparable across all reconstructions (median, 10.4-11.3 HU; P ≥ .112 for all), regardless of the selection of the IMAR preset or the absence of IMAR.
• Subjective evaluation highly favoured the IMAR_dental preset, with the highest preference probability for popliteal artery assessability (0.92; 95% CI, 0.90-0.93); pairwise odds ratios ranged from 7.8 to 63.9 (P < .001 for all).

IN PRACTICE

"Despite its misleading name, IMAR_Dental provides the strongest reduction of metal artefacts in UHR [ultra-high-resolution]-PCCTA of the leg, allowing for the best assessability of the popliteal vasculature in patients with total knee endoprosthesis," the authors wrote.

SOURCE

The study was led by Henner Huflage, MD, University Hospital Würzburg, Würzburg, Germany. It was published online on July 01, 2026, in Academic Radiology.

LIMITATIONS

The study was limited by the evaluation of hardware from a single vendor, the primary focus on image quality and diagnostic assessability rather than diagnostic accuracy against an external reference standard, implant-related heterogeneity in material and design, and conclusions being specific to popliteal artery assessment in the context of knee arthroplasty.

DISCLOSURES

No funding information was provided for this study. One author reported receiving financial support from Siemens Healthineers. Four authors disclosed having professional relationships with Siemens Healthineers that involved receiving consulting, advisory, speaking, or lecture fees.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.