Korean J Radiol.  2020 Apr;21(4):462-470. 10.3348/kjr.2019.0449.

Perceived Dark Rim Artifact in First-Pass Myocardial Perfusion Magnetic Resonance Imaging Due to Visual Illusion

Affiliations
  • 1Division of Mechanical and Biomedical Engineering, Ewha Womans University, Seoul, Korea. shinage@gmail.com
  • 2Department of Medicine, Case Western Reserve University, Cleveland, OH, USA.
  • 3Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA, USA.
  • 4Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.

Abstract


OBJECTIVE
To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images.
MATERIALS AND METHODS
Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders.
RESULTS
k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging −1.07 to −0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation.
CONCLUSION
Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

Keyword

Dark rim artifact; Visual illusion; Mach band; Myocardial perfusion MRI

MeSH Terms

Artifacts*
Healthy Volunteers
Heart
Heart Ventricles
Humans
Illusions*
Magnetic Resonance Angiography*
Magnetic Resonance Imaging
Myocardium
Perfusion*
Weights and Measures
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