Application of a Novel Metal Artifact Correction Algorithm in Flat-Panel CT After Coil Embolization of Brain Aneurysms: Intraindividual Comparison

Abstract

Purpose: To evaluate a novel algorithm for correcting beam hardening artifacts caused by metal implants in computed tomography performed on a C-arm angiography system equipped with a flat panel (FP-CT).

Materials and Methods: 16 datasets of cerebral FP-CT acquisitions after coil embolization of brain aneurysms in the context of acute subarachnoid hemorrhage have been reconstructed by applying a soft tissue kernel with and without a novel reconstruction filter for metal artifact correction. Image reading was performed in multiplanar reformations (MPR) in average mode on a dedicated radiological workplace in comparison to the preinterventional native multisection CT (MS-CT) scan serving as the anatomic gold standard. Two independent radiologists performed image scoring following a defined scale in direct comparison of the image data with and without artifact correction. For statistical analysis, a random intercept model was calculated.

Results: The inter-rater agreement was very high (ICC = 86.3 %). The soft tissue image quality and visualization of the CSF spaces at the level of the implants was substantially improved. The additional metal artifact correction algorithm did not induce impairment of the subjective image quality in any other brain regions.

Conclusion: Adding metal artifact correction to FP-CT in an acute postinterventional setting helps to visualize the close vicinity of the aneurysm at a generally consistent image quality.

Citation Format:

• Buhk JH, Groth M, Sehner S et al. Application of a Novel Metal Artifact Correction Algorithm in Flat-Panel CT After Coil Embolization of Brain Aneurysms: Intraindividual Comparison. Fortschr Röntgenstr 2013; 185: 824 – 829

Zusammenfassung

Zielsetzung: Evaluation eines neuen Rekonstruktionsalgorithmus zur Korrektur von Aufhärtungsartefakten durch metallene Implantate bei der Computertomografie an einer C-Bogen-Angiografie-Anlage mit Flächendetektoren (FD-CT).

Material und Methoden: 16 Datensätze zerebraler FD-CT Akquisitionen nach Coil-Embolisation von Hirnarterienaneurysmen im Rahmen einer akuten Subarachnoidalblutung wurden verwendet. Die Daten wurden mit einem Weichteil-Kernel zu isotropen Quellschichten rekonstruiert, jeweils mit und ohne Anwendung des neuen Rekonstruktionsfilters zur Metallartefaktreduktion. Bildbetrachtung und Auswertung erfolgten an einer radiologischen Arbeitsstation unter Verwendung multiplanarer Reformatierungen. Als anatomischer Goldstandard diente das präinterventionelle native Mehrzeilen-Computertomogramm (MS-CT). Zwei unabhängige Radiologen führten die Bildbewertung anhand einer definierten 4-Punkte-Skala durch. Die statistische Prüfung erfolgte in einem Random-Intercept-Modell.

Ergebnisse: Die Interrater-Reliabilität war sehr hoch (ICC: 86 %). Die Bewertungen für die betroffene Region waren signifikant besser unter Anwendung der Metallartefaktreduktion. Die subjektive Qualität der Darstellung der übrigen Regionen in der FD-CT wurde durch den zusätzlichen Filter nicht beeinflusst.

Schlussfolgerungen: Der neue Metallartefaktreduktionsalgorithmus ermöglicht eine verbesserte Erkennbarkeit der direkten Umgebung eines akut behandelten Aneurysmas in der FD-CT bei konstanter Gesamtqualität der Untersuchung.

Key words

brain - CT - interventional procedures - aneurysm - technical aspects

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