Thick-section reformatting of thinly collimated helical CT for reduction of skull base-related artifacts.
OBJECTIVE
Our purpose was to evaluate thick-section reformatted helical CT of the brain base as a technique for reducing skull base-related artifacts and to compare it with conventional CT.


METHODS
Twenty-three patients with suspected intracranial abnormalities related to the brain base, as determined either by clinical examination or at the time of imaging, were evaluated with contrast-enhanced conventional CT of the brain (5-mm collimation, 140 kVp, 170 mA, 2-sec rotation time) and reformatted helical CT (1-mm collimation, 1.5 pitch, 120 kVp, 220 mA). Helical sections were reformatted to a thickness of 5 mm by a volume-averaging algorithm using a computer workstation. Three observers retrospectively and blindly reviewed the images and qualitatively scored artifacts at the foramen magnum, middle cranial fossa, anterior cranial fossa, interpetrous region, and internal occipital protuberance. Image graininess and observer confidence were also scored. Paired statistical analyses using score differences in each patient were possible.


RESULTS
Reformatted helical CT reduced skull base-related artifacts across all five anatomic regions (p < 0.05). The foramen magnum showed the greatest reduction in artifacts and the anterior cranial fossa the least. Image graininess was increased on reformatted CT compared with conventional CT (p < 0.05), but observer confidence remained higher for reformatted CT (p < 0.05). Total additional scan time was 3.15 +/- 0.38 min with 5.3 +/- 1.2 min required for reformatting.


CONCLUSIONS
Reformatted CT significantly decreases skull base-related artifacts in the brain, improving confidence in evaluation of the brain base and adding an average of only 8.45 +/- 1.6 min of scanning and processing time to each examination.
Alberico
R A
RA
Department of Radiology, Neuroradiology/Head and Neck Imaging, Roswell Park Cancer Institute, Elm St. and Carlton St., Buffalo, NY 14263, USA.
Loud
P
P
Pollina
J
J
Greco
W
W
Patel
M
M
Klufas
R
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D001927:Brain Diseases / Q000000981:diagnostic imaging*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D003199:Computer Systems; D003287:Contrast Media; D005260:Female; D005539:Foramen Magnum / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009777:Occipital Bone / Q000000981:diagnostic imaging; D010579:Petrous Bone / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement; D012189:Retrospective Studies; D016037:Single-Blind Method; D019291:Skull Base / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media