Hui Zheng, Presenter: Nothing to Disclose

Yuhua Li, Abstract Co-Author: Nothing to Disclose

Wenjun Cao, Abstract Co-Author: Nothing to Disclose

Ming Liu, Abstract Co-Author: Nothing to Disclose

Dengbin Wang MD, PhD, Abstract Co-Author: Nothing to Disclose

To evaluate the visualization of the temporal bone using low-dose 256-slice CT,we scanned one exsomatized cadaveric head at multiple levels of mAs and kV .This optimized protocol was used to examine pediatric patients. We analyzed the feasibility of low dose temporal bone CT in children and evaluate the image quality and radiation dose of a low-dose versus.

One exsomatized cadaveric head was scanned repeatedly at three levels tube tensions from 120 to 80kV.And at every kV,multiple mAs were used from 250mAs until the image quality was insufficient.Noise was measured as the standard deviation in HU within the region the brain stem. All databases were subjectively evaluated by 2 experienced  radiologists.The visibility of 16 anatomical landmarks was scored using a five point scale. The  noise and effective dose were compared with each other. The optimized low dose protocol was used to examine 27 consecutive chidren. We retrospectively analyzed 36 examinations underwent a standard temporal bone CT acquired with 120kV,250mAs.The image quality and the effective dose were analyzed. Image quality score frequencies were calculated for each group.The children were then divided into 5 groups according to age-specific effective dose conversion coefficient.The effective dose of different age groups were compared in both low and high protocol.And then we compared the effective dose between the two protocols at the same age.  

CT radiation dose was significantly reduced when the parameters was selected 100kV,70mAs. Most of the anatomical landmarks were delineated no significantly difference though the increasd noise.The frequency of score 5 was significantly lower for the low-dose scans versus high,however the frequency of 4 was significantly higher .The frenquency of the scores 1 and 2 was none for both protocols.

Low-dose temporal bone CT scans allow an accurate evaluation of middle and inner ear structures in children though reduced image quality compared with that in high-dose scans.The radiation dose was 5~6 times below standard protocol used in daily work. The effective dose for infants is higher than the older children underwent the same protocol.

Postoperative CT of cochlear implants should provide information on the precise localization of the implant and its individual electrode.

Zheng, H, Li, Y, Cao, W, Liu, M, Wang, D, Low-dose Temporal Bone CT in Children: Feasibility and Image Quality.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13027370.html