%0 Journal Article
%T Ablation margin assessment of liver tumors with intravenous contrast-enhanced C-arm computed tomography
%A Mi Sung Kim
%A Sarabjeet Singh
%A Elkan Halpern
%A Sanjay Saini
%J World Journal of Radiology
%D 2012
%I Baishideng Publishing Group Co. Limited
%R 10.4329/wjr.v4.i3.102
%X AIM: To determine the influence of anthropomorphic parameters on the relationship between patient centering, mean computed tomography (CT) numbers and quantitative image noise in abdominal CT. METHODS: Our Institutional Review Board approved study included 395 patients (age range 21-108, years; male:female = 195:200) who underwent contrast-enhanced abdominal CT on a 16-section multi-detector row scanner (GE LightSpeed 16). Patient centering in the gantry isocenter was measured from the lateral localizer radiograph (off center S = patient off centered superior to isocenter; off center I = patient off centered inferior to isocenter). Mean CT numbers (Hounsfield Units: HU) and noise (standard deviation of CT numbers: SD) were measured in the anterior (aHU, aSD) and posterior (pHU, pSD) abdominal wall subcutaneous fat and liver parenchyma (LivHU, LivSD) at the level of the porta hepatis. Patients¡¯ age, gender, weight, body mass index and maximal anteroposterior diameter were recorded. The data were analyzed using linear regression analysis. RESULTS: Most patients (81%; 320/395) were not correctly centered in the gantry isocenter for abdominal CT scanning. Mean CT numbers in the abdominal wall increased significantly with an increase in the off-centering distance, regardless of the direction of the off-center (P < 0.05). There was a substantial increase in pSD (P = 0.01) and LivSD (P = 0.017) with off-centering. Change in mean CT numbers and image noise along the off-center distance was influenced by the patient size (P < 0.01). CONCLUSION: Inappropriate patient centering for CT scanning adversely affects the reliability of mean CT numbers and image noise.
%K Automatic exposure control
%K Computed tomography radiation dose reduction
%K Patient offcentering
%K Tube current modulation
%U http://www.wjgnet.com/1949-8470/full/v4/i3/102.htm