Thorax artifacts in CT – Air embolism or other causes?

Background: The existence of air in hollow organs in the thoracic cavity constitutes a life-threatening situation most of the times. However, sometimes in thoracic Computed Tomography (CT) there are artifacts from different sources that could mimic air densities, disorientating the diagnosis. Materials and Methods: 100 patients (46 females and 54 males, mean age: 60 years, range: 20-90 years), who had been routinely scanned in the area of thorax using three different imaging protocols (follow up, aorta, pulmonary vessels) were retrospectively studied. In 67 cases, contrast agent was used during the examination. Every case was studied by two specialists. Results: Artifacts in pulmonary veins were observed in 38 of the cases. Of these artifacts 27 stemmed from contrast agent, calcifications in the vessels, metallic implants, movement of the patient, malfunction of a detector due to the size of field of view (FOV) or due to the existence of contrast agent on the examination table of the CT scanner. In 11 cases, small amounts of air had been inserted into blood circulation during contrast injection. Conclusions: This study characterized and classified many artifacts related to thorax CT in order to separate them from other serious thoracic pathologies (e.g. aortic dissection, ulcer of veins or arteries). The knowledge and identification of the different types of artifacts is very important in order to avoid the risk of misdiagnosis. © 2021 Novin Medical Radiation Institute. All rights reserved

Reduction of motion, truncation and flow artifacts using BLADE sequences in cervical spine MR imaging

Purpose: To assess the efficacy of the BLADE technique (MR imaging with 'rotating blade-like k-space covering') to significantly reduce motion, truncation, flow and other artifacts in cervical spine compared to the conventional technique. Materials and methods: In eighty consecutive subjects, who had been routinely scanned for cervical spine examination, the following pairs of sequences were compared: a) T2 TSE SAG vs. T2 TSE SAG BLADE and b) T2 TIRM SAG vs. T2 TIRM SAG BLADE. A quantitative analysis was performed using the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measures. A qualitative analysis was also performed by two radiologists, who graded seven image characteristics on a 5-point scale (0: non-visualization; 1: poor; 2: average; 3: good; 4: excellent). The observers also evaluated the presence of image artifacts (motion, truncation, flow, indentation). Results: In quantitative analysis, the CNR values of the CSF/SC between TIRM SAG and TIRM SAG BLADE were found to present statistically significant differences (p. <. 0.001). Regarding motion and truncation artifacts, the T2 TSE BLADE SAG was superior compared to the T2 TSE SAG, and the T2 TIRM BLADE SAG was superior compared to the T2 TIRM SAG. Regarding flow artifacts, T2 TIRM BLADE SAG eliminated more artifacts than T2 TIRM SAG. Conclusions: In cervical spine MRI, BLADE sequences appear to significantly reduce motion, truncation and flow artifacts and improve image quality. BLADE sequences are proposed to be used for uncooperative subjects. Nevertheless, more research needs to be done by testing additional specific pathologies. © 2015 Elsevier Inc