Gas bubble motion artifact in MDCT

Abstract

Objective: The purpose of our study was to characterize the imaging features of an MDCT artifact caused by gas bubble motion.

Materials and methods: For the period 2002-2006, the CT images of 10 patients that revealed a curvilinear artifact thought to be due to a gas bubble moving during CT acquisition were retrospectively identified and reviewed by an attending body radiologist. The clinical images were acquired on MDCT scanners. A phantom containing water and moving air bubbles (gas injection rates of 0.1 and 0.5 mL/s) was designed, built, and scanned using a 16-MDCT scanner. Computer simulation was used to test our hypothesis that these observed artifacts originated from moving gas bubbles.

Results: Semicircular tubular CT artifacts with attenuation close to that of air were observed in all 10 clinical cases. The acquired MDCT images from the phantom and the computer simulations showed tubular air-attenuation semicircular artifacts that closely matched the imaging findings on the 10 clinical cases. Increased rates of bubble injection multiplied the artifact. Based on the computer simulation, the precise appearance of the artifact depends on the bubble location and velocity relative to the rotation of the CT scanner.

Conclusion: Gas bubble motion during CT generates a semicircular air-attenuation artifact that has not been previously described to our knowledge. The artifact is typically found in bowel and other liquid-containing structures in which a bubble of gas floats up through a liquid medium during CT.