Metal artifact reduction for intracranial projectiles on post mortem computed tomography.

Area of Science:

• Forensic Radiology
• Medical Imaging
• Pathology

Background:

• Metallic ballistic projectiles in the cranium cause significant artifacts in post-mortem computed tomography (CT) imaging.
• These artifacts can obscure critical diagnostic information, complicating forensic analysis.

Purpose of the Study:

• To evaluate the effectiveness of projection-based single-energy metal artifact reduction (SEMAR) in improving cranial post-mortem CT image quality.
• To compare CT scans with and without SEMAR in cadavers containing intracranial metallic ballistic projectiles.

Main Methods:

• Post-mortem CT scans were acquired from 11 cadavers with ballistic head wounds and metallic fragments.
• Scans were performed using both conventional iterative reconstruction (IR) and SEMAR techniques.
• Image analysis included quantifying artifact burden (ATS, NIZ/TA ratios) and assessing the detectability of extra-axial hemorrhage (EAH) and subarachnoid hemorrhage (SAH).

Main Results:

• SEMAR significantly reduced the artifact total surface (ATS) ratio and the non-interpretable zone to total area (NIZ/TA) ratio compared to conventional IR.
• SEMAR decreased the artifact burden, with NIZ/TA ratios dropping from 42.5% to 11.6%.
• Interobserver reproducibility for diagnosing EAH was good with SEMAR (0.75) versus excellent with conventional IR (0.82), with SEMAR reducing uncertain EAH diagnoses in most subjects.

Conclusions:

• SEMAR effectively reduces metallic artifacts in post-mortem cranial CT.
• The use of SEMAR increases diagnostic confidence for extra-axial hemorrhage (EAH) in cases involving metallic ballistic projectiles.
• SEMAR did not significantly impact the diagnosis of subarachnoid hemorrhage (SAH).