Metal artifact reduction for intracranial projectiles on post mortem computed tomography
N Douis1, A S Formery2, G Hossu3
1Guilloz Imaging Department, Hopital Central, CHU Nancy, 54000 Nancy, France.
Purpose:
To compare the image quality of cranial post-mortem computed tomography (CT) obtained with and without projection-based single-energy metal artifact reduction (SEMAR) in cadavers with intracranial metallic ballistic projectiles.
Materials And Methods:
From January 2017 to January 2018, cadavers with ballistic projectile head wounds with metal fragments and without massive head destruction were investigated using post-mortem CT. All subjects underwent CT using a conventional iterative reconstruction (IR) and SEMAR. To evaluate the impact of metallic artifacts, the total intracranial area (TA), non-interpretable zone (NIZ), disturbed interpretation zone (DZ), and artifact total surface (ATS) were delineated. Two independent readers identified extra-axial hemorrhage (EAH) and subarachnoid hemorrhage (SAH). Autopsy reports were used as the standard of reference.
Results:
Eleven corpses (10 males, 1 female; mean age, 62.8±17.9 [SD] years) were evaluated. SEMAR showed a significant decrease in the ATS ratio with respect to conventional IR (72.1±26.1 [SD] % [range: 26.8-99.1] vs. 86.4±17.8 [SD] % [range: 37.2-100]; P<0.001) and NIZ/TA ratios (11.6±8.26% [range: 0.95-33.4] versus 42.5±30.5% [range: 3.86-100]; P<0.001). The interobserver reproducibility in diagnosing EAH and SAH was excellent with conventional IR (0.82) and good with SEMAR (0.75). SEMAR reduced uncertain diagnoses of EAH in 7 subjects for Reader 1 and in 6 for Reader 2, but did not influence the diagnosis of SAH for either reader.
Conclusion:
SEMAR reduces the influence of metallic artifacts and increases the confidence with which the diagnosis of EAH can be made on post-mortem CT.
