Reduction of peristalsis-related gastrointestinal streak artifacts with dual-energy CT: a patient and phantom study

Abstract

Objective The purpose of the study was to assess the ability of rapid-kV switching (rs) dual-energy computed tomography (DECT) to reduce peristalsis-related streak artifact. Methods rsDECT images of 100 consecutive patients (48 male, 52 female, mean age 57 years) were retrospectively evaluated in this institutional review board–approved study. Image reconstructions included virtual monochromatic 70 and 120 keV images, as well as iodine(-water) and water(-iodine) material decomposition images. We recorded the presence and severity of artifacts qualitatively (4-point scale) and quantitatively [iodine/water concentrations, Hounsfield units, gray scale values (GY)] and compared to corresponding unaffected reference tissue. Similar measures were obtained in DECT images of a peristalsis phantom. Wilcoxon signed-rank and paired t tests were used to compare results between different image reconstructions. Results Peristalsis-related streak artifacts were found in 49 (49%) of the DECT examinations. Artifacts were significantly more severe in 70, 120, and water(-iodine) images than in iodine(-water) images (qualitative readout P < 0.001, each). Quantitative measurements were significantly different between the artifact and the reference tissue in 70, 120 keV, and water(-iodine) images (P < 0.001 for both HU and GY for each image reconstruction), but not significantly different in iodine(-water) images (iodine concentrations P = 0.088 and GY P = 0.111). Similar results were seen in the peristalsis DECT phantom study. Conclusions Peristalsis-related streak artifacts seen in 70, 120 keV, and water(-iodine) images are substantially reduced in iodine(-water) images at rsDECT.

Benefit of iodine density images to reduce out-of-field image artifacts at rapid kVp switching dual-energy CT

“…This in turn causes them to appear in maximal severity in the water density image, as water also exhibits attenuation properties independent of X-ray energy within the diagnostic energy range (19). Correspondingly, they are largely absent in the iodine density image, as this image reconstruction shows projection data which exhibit a reduction in attenuation from low to high kVp.…”

“…Further study will be needed on these other DECT implementations. Fourthly, the introduction of other artifacts, such as beam hardening (28), by iodine density images were not evaluated. Fifthly, since topogram images are not routinely saved in our CT scans, we did not assess the value of topograms for predicting the value of DECT reconstructions to improve out-of-field artifacts.…”

“…The iodine density image is known to benefit many thoracoabdominal imaging indications, including to evaluate for possible pulmonary embolus (15), abdominal perfusion (16), and to detect hyper- or hypovascular masses in the liver and pancreas (17, 18). In addition to these diagnostic capabilities, iodine density images have also recently been shown to reduce intestinal peristalsis motion artifacts (19). Similar to motion artifact, out-of-field artifacts arise from errors in signal mapping at CT.…”

Gastrointestinal Applications of Iodine Quantification Using Dual-Energy CT: A Systematic Review

“…The first study by Lourenco et al [62] demonstrated a significant reduction in IC in bowel segments suffering from acute bowel ischemia. The second study by Winklhofer et al [63] demonstrated that peristalsis-related streak artifacts can be reduced using iodine maps (Studies shown in Table 4). Significant difference between squamous cell carcinoma and adenocarcinoma in both phases (nIC-A: p = 0.02, nIC-V: p = 0.00)…”

Opportunities for new CT contrast agents to maximize the diagnostic potential of emerging spectral CT technologies

“…DECT and photon-counting, energy-discriminating (PCED) CT are two major types of “spectral” CT, in which the unique, energy-dependent attenuating characteristics of materials can provide new diagnostic information[13]. The most-published benefits of spectral CT are reduced image artifacts [14–16], differentiation between tissue compositions [17], and improved detection and quantification of iodine- and barium-based contrast material concentrations [3] with a single pass of the CT scanner. The medical community is gradually embracing DECT for these benefits.…”