Retrospective Analysis of Artifacts in Four-Dimensional CT Images of 50 Abdominal and Thoracic Radiotherapy Patients

Abstract

Purpose-To quantify the type, frequency and magnitude of artifacts in four-dimensional (4D) CT images acquired using a multislice cine method.Methods and Materials-Fifty consecutive patients, who underwent 4D-CT scanning and radiotherapy for thoracic or abdominal cancers, were included in this study. All the 4D-CT scans were performed on the GE multislice PET/CT scanner with the Varian RPM system in cine mode. The GE Advantage 4D software was used to create 4D-CT data sets. The artifacts were then visually and quantitatively analyzed. We further performed statistical analyses to evaluate the relationships between patient-or breathing pattern-related parameters and the occurrence as well as magnitude of artifacts.Results-It was found that 45 of 50 patients (90%) had at least one artifact (other than blurring) with a mean magnitude of 11.6 mm (range, 4.4 -56.0 mm) in the diaphragm or heart. We also observed at least one artifact in 6 of 20 lung or mediastinal tumors (30%). Statistical analysis revealed that there were significant differences between several breathing pattern-related parameters, including abdominal displacement (p < 0.01), for the subgroups of patients with and without artifacts. The magnitude of an artifact was found to be significantly but weakly correlated with the abdominal displacement difference between two adjacent couch positions (R = 0.34, p < 0.01).Conclusions-This study has identified that the frequency and magnitude of artifacts in 4D-CT is alarmingly high. Significant improvement is needed in 4D-CT imaging.

Evaluation of automatic contour propagation in T2‐weighted 4DMRI for normal‐tissue motion assessment using internal organ‐at‐risk volume (IRV)

“…Therefore, the accuracy and reliability of the DIR‐based propagated contours among 4DMRI images are expected to be higher (Fig. 2A) than 4DCT images with low soft‐tissue contrast and frequent binning artifacts 28, 49, 50. This explains the low intra‐observer (Fig.…”

“…The superior contour quality implies that the contour quality in navigator‐triggered 4DMRI is better than that of 4DCT where an external surrogate is almost always used. In fact, binning artifacts are commonly present in 4DCT49, 50 and can cause up to 90–110% gross tumor volume changes in lung cancer 53, 54. The high 4DMRI image quality and high soft‐tissue contrast improve that DIR and therefore contribute to the high OAR contour quality.…”

The impact of audiovisual biofeedback on 4D functional and anatomic imaging: Results of a lung cancer pilot study

“…In PET imaging, respiratory motion artifacts may result in underestimation of the corresponding standardized uptake value (SUV) and overestimation of the tumor volume [1]. In CT imaging, respiration may cause the four types of artifacts (blurring, duplicate structure, overlapping structure, and incomplete structure) which potentially deteriorate the quality of CT images [2]. Thus, respiratory motion management is needed to mitigate such artifacts, which is achieved through four-dimensional (4D) imaging.…”

“…However, 4D imaging may fail to reduce artifacts if breathing is irregular during data acquisition due to inadequate respiratory motion sampling for image reconstruction [2], [3]. For this reason, respiratory training or coaching is a commonly used technique to reduce irregularity in breathing cycles.…”

An automated method for comparing motion artifacts in cine four‐dimensional computed tomography images

“…A 4D image set is then reconstructed by viewing the 3D images in sequence for each image bin. The current acquisition and sorting methods led to significant motion artifacts 4 , 6 (artifacts in one study measured $<4\hspace{0.17em}\text{mm}$ in 90% of scans (5) ). The occurrence of artifacts is mainly caused by inaccurate determination of the respiratory phase (4) .…”