Low pitch significantly reduces helical artifacts in abdominal CT

• Published in: European journal of radiology Vol. 166; p. 110977
• Main Authors: Ahmad, Moiz, Sun, Peng, Peterson, Christine B., Anderson, Marcus R., Liu, Xinming, Morani, Ajaykumar C., Jensen, Corey T.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.09.2023
• Subjects: Abdomen; Abdomen - diagnostic imaging; Adult; Humans; Motion; Phantoms, Imaging; Pitch; Retrospective Studies; Technique; Tomography, X-Ray Computed - methods; Pitch; Artifacts; CT; Technique; Abdomen
• ISSN: 0720-048X; 1872-7727; 1872-7727
• DOI: 10.1016/j.ejrad.2023.110977

•Low pitch CT scans reduce helical artifacts produced at bowel interfaces.•While controlling other settings to prevent increased radiation dose, consideration should be made for low helical pitch scanning to improve image quality, particularly when bowel or peritoneal pathology is suspected.•Modern CT scanners still allow fast scanning even at low pitch. High helical pitch scanning minimizes scan times in CT imaging, and thus also minimizes motion artifact and mis-synchronization with contrast bolus. However, high pitch produces helical artifacts that may adversely affect diagnostic image quality. This study aims to determine the severity and incidence of helical artifacts in abdominal CT imaging and their relation to the helical pitch scan parameter. To obtain a dataset with varying pitch values, we used CT exam data both internal and external to our center. A cohort of 59 consecutive adult patients receiving an abdomen CT examination at our center with an accompanying prior examination from an external center was selected for retrospective review. Two expert observers performed a blinded rating of helical artifact in each examination using a five-point Likert scale. The incidence of artifacts with respect to the helical pitch was assessed. A generalized linear mixed-effects regression (GLMER) model, with study arm (Internal or External to our center) and helical pitch as the fixed-effect predictor variables, was fit to the artifact ratings, and significance of the predictor variables was tested. For a pitch of <0.75, the proportion of exams with mild or worse helical artifacts (Likert scores of 1–3) was <1%. The proportion increased to 16% for exams with pitch between 0.75 and 1.2, and further increased to 78% for exams with a pitch greater than 1.2. Pitch was significantly associated with helical artifact in the GLMER model (p = 2.8 × 10−9), while study arm was not a significant factor (p = 0.76). The incidence and severity of helical artifact increased with helical pitch. This difference persisted even after accounting for the potential confounding factor of the center where the study was performed.