Metal artifact reduction algorithm for image quality improvement of cone-beam CT images of medium or large cerebral aneurysms treated with stent-assisted coil embolization

  • Satoshi Murai
  • Masafumi HiramatsuEmail author
  • Yuji Takasugi
  • Yu Takahashi
  • Naoya Kidani
  • Shingo Nishihiro
  • Yukei Shinji
  • Jun Haruma
  • Tomohito Hishikawa
  • Kenji Sugiu
  • Isao Date
Interventional Neuroradiology



The aim of the present study was to assess image quality improvement using a metal artifact reduction (MAR) algorithm in cases of medium or large cerebral aneurysms treated with stent-assisted coil embolization (SAC), and to analyze factors associated with the usefulness of the MAR algorithm.


We retrospectively evaluated the cone-beam computed tomography (CBCT) data sets of 18 patients with cerebral aneurysms treated with SAC. For subjective analysis, images of all cases with and without MAR processing were evaluated by five neurosurgeons based on four criteria using a five-point scale. For objective analysis, the CT values of all cases with and without MAR processing were calculated. In addition, we assessed factors associated with the usefulness of the MAR by analyzing the nine cases in which the median score for criterion 1 improved by more than two points.


MAR processing improved the median scores for all four criteria in 17/18 cases (94.4%). Mean CT values of the region of interest at the site influenced by metal artifacts were significantly reduced after MAR processing. The maximum diameter of the coil mass (< 17 mm; odds ratio [OR], 4.0; 95% confidence interval [CI], 1.2–13.9; p = 0.02) and vessel length covered by metal artifacts (< 24 mm; OR, 2.3; 95% CI, 1.1–4.7; p = 0.03) was significantly associated with the usefulness of the MAR.


This study suggests the feasibility of a MAR algorithm to improve the image quality of CBCT images in patients who have undergone SAC for medium or large aneurysms.


Metal artifact reduction Cone-beam CT Stent-assisted coil embolization Coil mass 



Anterior choroidal artery


Anterior communicating artery


Basilar artery


Cavernous sinus


Contrast-enhanced cone-beam computed tomography


Field of view


Hounsfield unit


Internal carotid artery


Interquartile range


Metal artifact reduction


Middle cerebral artery


Maximum intensity projection


Posterior communicating artery


Receiver operating characteristic


Relative risk


Stent-assisted coil embolization


Superior cerebellar artery


Standard deviation


Superior hypophyseal artery


Vertebral artery



We thank Mr. C. Dahmani and Mr. I. Kojima (Siemens Healthcare) for technical support related to the metal artifact reduction software.

Funding information

This study was funded by Siemens Healthcare.

Compliance with ethical standards

Conflict of interest

The authors have received research grants from Siemens Healthcare. YT and MH–RELATED: Grant: Siemens Healthcare; Support for travel to meetings for the study and provision of writing assistance. KS–RELATED: Grant: Siemens Healthcare; Support for travel to meeting for the study and payment for lectures.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Satoshi Murai
    • 1
  • Masafumi Hiramatsu
    • 1
    Email author
  • Yuji Takasugi
    • 1
  • Yu Takahashi
    • 1
  • Naoya Kidani
    • 1
  • Shingo Nishihiro
    • 1
  • Yukei Shinji
    • 1
  • Jun Haruma
    • 1
  • Tomohito Hishikawa
    • 1
  • Kenji Sugiu
    • 1
  • Isao Date
    • 1
  1. 1.Department of Neurological SurgeryOkayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesOkayamaJapan

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