Defining window settings for abdominopelvic photon-counting CT virtual monoenergetic imaging: quantitative and...

Area of Science:

• Medical Imaging
• Radiology
• Photon-Counting CT Technology

Background:

• Virtual monoenergetic images (VMIs) at 60 keV are recommended for photon-counting CT (PCCT) soft tissue imaging, offering reduced radiation dose.
• Default windowing settings on 60 keV VMIs result in images appearing brighter than standard 120-kV CT, necessitating manual adjustments for optimal visualization.

Purpose of the Study:

• To determine optimal soft tissue and liver window settings for abdominopelvic imaging using PCCT at 60 and 70 keV.
• To quantitatively and qualitatively evaluate the impact of default versus optimized window settings on image quality.

Main Methods:

• Retrospective analysis of dual-phase abdominopelvic PCCT 60 and 70 keV VMIs from 39 patients.
• Radiologists manually adjusted window center/width settings for optimal soft tissue and liver visualization.
• Quantification of contrast-to-noise ratio (CNR) and display-CNR (dCNR) across different window settings; reader evaluation of image preference and overall impression.

Main Results:

• Mean CNR was significantly higher at 60 keV compared to 70 keV (p < 0.001).
• Optimized windowing at 60 keV substantially increased liver dCNR (75-92%) and soft tissue dCNR (27-51%) compared to default settings.
• Images viewed with optimal windowing at 60 keV received significantly higher reader rankings and impressions for both soft tissue and liver evaluation (p < 0.001).

Conclusions:

• Optimized window settings are critical for enhancing soft tissue and liver visualization on PCCT VMIs.
• The benefits of optimized windowing are particularly pronounced at 60 keV, improving diagnostic quality in abdominopelvic imaging.