Geometric Error Of 3-dimensional Coordinates Of Leksell Stereotactic Skull Frame System In 1.5 Tesla- And 3.0 Tesla-mriHisato Nakazawa1, Kobayashi Tatsuya2, Mori Yoshimasa2, Uchiyama Yukio2, Hagiwara Masahiro2, Yamada Masami21Nagoya, Japan 2Nagoya Kyoritsu Hospital, Nagoya, Japan Keywords: technique, magnetic resonance imaging, Imaging, gamma knife, stereotactic frameInteractive ManuscriptAsk Questions of this Manuscript: What is the background behind your study?Elekta provides some types of cranial screws of different materials, such as aluminum, titanium and aluminum with tungsten-tip for skull frame placement. What is the purpose of your study?The aim of this study is to evaluate geometrical distortion produced by these screws. Describe your patient group.. Describe what you did.A grid-pattern acrylic box phantom filled with copper sulfate solution was placed on the Leksell skull frame using screws of titanium or those of aluminum with tungsten-tip. It was scanned with CT, 1.5T-MRI, and 3.0T-MRI. The 3-dimensional coordinates in 1.5T-MRI and 3.0T-MRI were compared with those in CT Describe your main findings.In both 1.5T- and 3.0T-MRI the errors of coordinates were least around the center, (x, y, z) = (100,100,100), with both 2 types of screws. With tungsten-tipped aluminum screws errors of coordinates were less than 1 mm in 1.5T-MRI. On the other hand, with titanium screws those were between 1 mm and 2 mm in 1.5T-MRI. Using 3T-MRI, errors with screws of tungsten-tipped aluminum were less than 1.5 mm around the center and up to 3 mm around parietal area, and those with screws of titanium were between 1 mm and 2 mm around the center and up to 6 mm around parietal area. Describe the main limitation of this study.This is a retrospective study. Describe your main conclusion.Even in 1.5T-MRI, the errors of coordinates were more with titanium screws than with tungsten-tipped aluminum ones. The distortion is more in 3T-MRI than in 1.5T-MRI with either type of screw. Describe the importance of your findings and how they can be used by others.3.0T-MRI is thought to be more susceptible to distortion by various conditions than 1.5T-MRI. We have to take image distortion into considerations, even if we use 3.0T-MRI by image fusion on CT. Elekta provides some types of cranial screws of different materials, such as aluminum, titanium and aluminum with tungsten-tip for skull frame placement. The aim of this study is to evaluate geometrical distortion produced by these screws. . A grid-pattern acrylic box phantom filled with copper sulfate solution was placed on the Leksell skull frame using screws of titanium or those of aluminum with tungsten-tip. It was scanned with CT, 1.5T-MRI, and 3.0T-MRI. The 3-dimensional coordinates in 1.5T-MRI and 3.0T-MRI were compared with those in CT In both 1.5T- and 3.0T-MRI the errors of coordinates were least around the center, (x, y, z) = (100,100,100), with both 2 types of screws. With tungsten-tipped aluminum screws errors of coordinates were less than 1 mm in 1.5T-MRI. On the other hand, with titanium screws those were between 1 mm and 2 mm in 1.5T-MRI. Using 3T-MRI, errors with screws of tungsten-tipped aluminum were less than 1.5 mm around the center and up to 3 mm around parietal area, and those with screws of titanium were between 1 mm and 2 mm around the center and up to 6 mm around parietal area. This is a retrospective study. Even in 1.5T-MRI, the errors of coordinates were more with titanium screws than with tungsten-tipped aluminum ones. The distortion is more in 3T-MRI than in 1.5T-MRI with either type of screw. 3.0T-MRI is thought to be more susceptible to distortion by various conditions than 1.5T-MRI. We have to take image distortion into considerations, even if we use 3.0T-MRI by image fusion on CT. Project Roles:
H. Nakazawa (), K. Tatsuya (), M. Yoshimasa (), U. Yukio (), H. Masahiro (), Y. Masami ()
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