Metal artefact reduction for patients with metallic dental fillings in helical neck computed tomography: comparison of adaptive iterative dose reduction 3D (AIDR 3D), forward-projected model-based iterative reconstruction solution (FIRST) and AIDR 3D with single-energy metal artefact reduction (SEMAR).
OBJECTIVE
To compare the differences in metal artefact degree and the depiction of structures in helical neck CT, in patients with metallic dental fillings, among adaptive iterative dose reduction three dimensional (AIDR 3D), forward-projected model-based iterative reconstruction solution (FIRST) and AIDR 3D with single-energy metal artefact reduction (SEMAR-A).


METHODS
In this retrospective clinical study, 22 patients (males, 13; females, 9; mean age, 64.6 ± 12.6 years) with metallic dental fillings who underwent contrast-enhanced helical CT involving the oropharyngeal region were included. Neck axial images were reconstructed with AIDR 3D, FIRST and SEMAR-A. Metal artefact degree and depiction of structures (the apex and root of the tongue, parapharyngeal space, superior portion of the internal jugular chain and parotid gland) were evaluated on a four-point scale by two radiologists. Placing regions of interest, standard deviations of the oral cavity and nuchal muscle (at the slice where no metal exists) were measured and metal artefact indices were calculated (the square root of the difference of the squares of them).


RESULTS
In SEMAR-A, metal artefact was significantly reduced and depictions of all structures were significantly improved compared with those in FIRST and AIDR 3D (p ≤ 0.001, sign test). Metal artefact index for the oral cavity in AIDR 3D/FIRST/SEMAR-A was 572.0/477.7/88.4, and significant differences were seen between each reconstruction algorithm (p < 0.0001, Wilcoxon signed-rank test).


CONCLUSIONS
SEMAR-A could provide images with lesser metal artefact and better depiction of structures than AIDR 3D and FIRST.
Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Koichiro
K
Yasaka
Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Kouhei
K
Kamiya
Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Ryusuke
R
Irie
Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Eriko
E
Maeda
Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Jiro
J
Sato
Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Kuni
K
Ohtomo
D000368:Aged; D000465:Algorithms; D016477:Artifacts; D003287:Contrast Media; D003722:Dental Alloys / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007601:Jugular Veins / Q000000981:diagnostic imaging; D008297:Male; D008670:Metals / Q000737:chemistry*; D008875:Middle Aged; D009960:Oropharynx / Q000000981:diagnostic imaging; D010306:Parotid Gland / Q000000981:diagnostic imaging; D010614:Pharynx / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods*; D014059:Tongue / Q000000981:diagnostic imaging
D003287:Contrast Media; D003722:Dental Alloys; D008670:Metals
CT; artefact; metal; neck; pharynx