Intra- and inter-scanner CT variability and their impact on diagnostic tasks

Area of Science:

• Medical Imaging Physics
• Radiology
• Quantitative Imaging

Background:

• Computed Tomography (CT) technology advancements have increased access to medical imaging.
• However, scanner variability introduces inconsistencies that may affect patient care.
• Standardization of CT imaging protocols is essential for reliable diagnostic outcomes.

Purpose of the Study:

• To investigate the impact of intra-scanner and inter-scanner variability on CT image quality.
• To assess the influence of scanner variability on quantitative imaging tasks, specifically lesion detectability.
• To quantify the variability in the detectability index (d') across different CT scanners.

Main Methods:

• Analysis of 813 clinical phantom image sets from the COPDGene study.
• Evaluation of image quality metrics: Noise Power Spectrum (NPS) and Modulation Transfer Function (MTF).
• Calculation of the detectability index (d') for 12 hypothetical lesion detection tasks (lung and liver).

Main Results:

• Observed intra-scanner variability in NPS and MTF for identical settings.
• Demonstrated inter-scanner variability in d' measurements across different CT scanner makes and models.
• Quantified intra-scanner variability up to 13.7% and inter-scanner variability up to 19.3% in the d' index.

Conclusions:

• CT scanner variability significantly affects image quality and lesion detection performance.
• The findings highlight the need to account for scanner variability in clinical practice.
• Development of virtual scanner models is motivated to mitigate observed variability in CT imaging.