title: Evaluation of a metal artifact reduction algorithm applied to post-interventional flat detector CT in comparison to pre-treatment CT in patients with acute subarachnoid haemorrhage.
abstract: OBJECTIVE
  Metal artefacts can impair accurate diagnosis of haemorrhage using flat detector CT (FD-CT), especially after aneurysm coiling. Within this work we evaluate a prototype metal artefact reduction algorithm by comparison of the artefact-reduced and the non-artefact-reduced FD-CT images to pre-treatment FD-CT and multi-slice CT images.
  
  
  METHODS
  Twenty-five patients with acute aneurysmal subarachnoid haemorrhage (SAH) were selected retrospectively. FD-CT and multi-slice CT before endovascular treatment as well as FD-CT data sets after treatment were available for all patients. The algorithm was applied to post-treatment FD-CT. The effect of the algorithm was evaluated utilizing the pre-post concordance of a modified Fisher score, a subjective image quality assessment, the range of the Hounsfield units within three ROIs, and the pre-post slice-wise Pearson correlation.
  
  
  RESULTS
  The pre-post concordance of the modified Fisher score, the subjective image quality, and the pre-post correlation of the ranges of the Hounsfield units were significantly higher for artefact-reduced than for non-artefact-reduced images. Within the metal-affected slices, the pre-post slice-wise Pearson correlation coefficient was higher for artefact-reduced than for non-artefact-reduced images.
  
  
  CONCLUSIONS
  The overall diagnostic quality of the artefact-reduced images was improved and reached the level of the pre-interventional FD-CT images. The metal-unaffected parts of the image were not modified.
  
  
  CONCLUSIONS
  • After coiling subarachnoid haemorrhage, metal artefacts seriously reduce FD-CT image quality. • This new metal artefact reduction algorithm is feasible for flat-detector CT. • After coiling, MAR is necessary for diagnostic quality of affected slices. • Slice-wise Pearson correlation is introduced to evaluate improvement of MAR in future studies. • Metal-unaffected parts of image are not modified by this MAR algorithm.
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054, Erlangen, Germany. Angelika.Mennecke@uk-erlangen.de.
authors.forename: Angelika
authors.initials: A
authors.lastname: Mennecke
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054, Erlangen, Germany.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Svergun
authors.affiliation: Siemens Healthcare GmbH, Simon-Hegele-Strasse 1, 91301, Forchheim, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Scholz
authors.affiliation: Siemens Medical Solutions, USA, Inc., 2501 N. Barrington Rd., Hoffman Estates, IL, 60192, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Royalty
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054, Erlangen, Germany.
authors.forename: Arnd
authors.initials: A
authors.lastname: Dörfler
authors.affiliation: Department of Neuroradiology, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054, Erlangen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Struffert
mesh_terms: D000208:Acute Disease; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Aneurysm; Artefacts; Cone beam CT; Multi-slice Computed Tomography; Subarachnoid Haemorrhage