Complementary contrast media for metal artifact reduction in dual-energy computed tomography

Abstract

Abstract. Metal artifacts have been a problem associated with computed tomography (CT) since its introduction. Recent techniques to mitigate this problem have included utilization of high-energy (keV) virtual monochromatic spectral (VMS) images, produced via dual-energy CT (DECT). A problem with these high-keV images is that contrast enhancement provided by all commercially available contrast media is severely reduced. Contrast agents based on higher atomic number elements can maintain contrast at the higher energy levels where artifacts are reduced. This study evaluated three such candidate elements: bismuth, tantalum, and tungsten, as well as two conventional contrast elements: iodine and barium. A water-based phantom with vials containing these five elements in solution, as well as different artifact-producing metal structures, was scanned with a DECT scanner capable of rapid operating voltage switching. In the VMS datasets, substantial reductions in the contrast were observed for iodine and barium, which suffered from contrast reductions of 97% and 91%, respectively, at 140 versus 40 keV. In comparison under the same conditions, the candidate agents demonstrated contrast enhancement reductions of only 20%, 29%, and 32% for tungsten, tantalum, and bismuth, respectively. At 140 versus 40 keV, metal artifact severity was reduced by 57% to 85% depending on the phantom configuration.

Evaluation of efficacy of metal artefact reduction technique using contrast media in Computed Tomography

“…SNR of stainless steel and titanium alloy is not significantly difference with p-value of 0.204. This is because the x-ray attenuation of contrast media is higher compared to the orthopedic screw [11,17]. Thus, the SNR value calculated for stainless steel and titanium alloy for contrast based phantom is not significantly difference.…”

“…This explained that contrast based phantom has lower noise and streaky image than non-contrast based phantom in CT images. This is because the x-ray attenuation of contrast media is higher compared to the orthopedic screw [11,17]. …”

“…However, the limitations are most of the techniques do not remove all sources of streaking artefacts, cause loss of spatial resolution in images and introduce the secondary artefacts that may lead to misinterpretation [8][9][10]. Other than reconstruction technique, the use of contrast media is also proposed as metal artefact reduction technique [11][12][13]. Contrast media are a group of medical drugs used to improve the visibility of internal organs and structures in imaging techniques.…”

“…Side effects range from contrast media range from a mild inconvenience, such as itching, delayed allergic reactions, anaphylactic reactions, and cutaneous reactions, to life-threatening emergencies [14]. Lambert et al (2015) study on the complementary of contrast media using bismuth, tantalum, and tungsten for patients with metal implants in dual-energy CT. They found that metal artefact severity was reduced in high-keV images across changes in the metal artefact types [11].…”

“…Lambert et al (2015) study on the complementary of contrast media using bismuth, tantalum, and tungsten for patients with metal implants in dual-energy CT. They found that metal artefact severity was reduced in high-keV images across changes in the metal artefact types [11]. Other study done by Pjontek et al (2015) found that contrast media and metal artefact reduction software (MARS) in angiographic CT is significantly improves image quality in patient after coiling or clipping [12].…”