Assessment of temporal resolution and detectability of moving objects in CT: A task-based image quality study

Area of Science:

• Medical Imaging Physics
• Radiological Sciences

Background:

• Traditional computed tomography (CT) image quality assessment lacks temporal resolution integration.
• This omission limits the evaluation of imaging protocols susceptible to motion blur.

Purpose of the Study:

• To develop a method for calculating temporal resolution in standard CT protocols.
• To introduce a spatiotemporal model observer for assessing moving object detectability based on speed.

Main Methods:

• Scanned phantoms with varying acquisition parameters (rotation time, pitch, collimation) on GE Revolution Apex and Siemens SOMATOM Force systems.
• Determined in-plane task-based transfer functions (TTF) and noise power spectra (NPS).
• Calculated temporal modulation transfer function (MTF) using phantom motion and measured longitudinal TTF with a tungsten wire.

Main Results:

• Temporal MTF effectively compared temporal resolution across different CT acquisition protocols.
• Higher rotation speeds, wider collimations, and increased pitch improved moving object detection.
• These parameter increases did not negatively impact in-plane or longitudinal image quality.

Conclusions:

• The developed method accurately quantifies CT temporal resolution.
• Optimizing parameters for motion detection enhances CT performance in dynamic imaging scenarios.
• Integrating temporal resolution into CT image quality assessment is crucial for protocols involving patient or object motion.