Mika Kitajima MD, Presenter: Nothing to Disclose

Seitaro Oda MD, Abstract Co-Author: Nothing to Disclose

Yoshinori Shigematsu MD, Abstract Co-Author: Nothing to Disclose

Daisuke Utsunomiya MD, Abstract Co-Author: Nothing to Disclose

Toshinori Hirai MD, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Consultant, DAIICHI SANKYO Group

To compare the image quality and radiation exposure on temporal bone CT acquired on a 320-row CT between axial-volume scan with iterative reconstruction (IR) and helical scan with filtered back projection (FBP).

We randomized 50 patients into two groups and acquired axial scans with IR in group 1 (n=22) and helical scans with FBP in group 2 (n=28). The CTDIvol, effective radiation dose, and imaging time in group 1 and 2 were 29.2 mGy, 0.37 mSv and 1.0 sec, and 48.6 mGy, 0.71 mSv, and 12.0 sec, respectively. Two neuroradiologists consensually recorded the overall image quality and visualization of 34 anatomic structures per ear (e.g., osseous spinal lamina, stapes crura, facial nerve canal) on a 4-point scale. We also compared the image noise and contrast-to-noise ratio (CNR) in the two groups. Mann-Whitney and unpaired t-tests were used for qualitative and quantitative assessments, respectively.

There was no significant difference in the overall image quality. At the comparison of individual anatomic structures, there was no significant difference in visualization of 35 structures except the osseous spinal lamina at the middle cochlear turn, round window membrane, and the vestibular aqueduct. There was no statistically significant difference in the mean image noise and CNR. An approximate reduction in the radiation dose and the imaging time of 48.1% and 92%, respectively, was obtained by axial volume scan with IR.

Temporal bone images acquired at 320-row CT using axial volume scanning and IR are of adequate diagnostic quality and allow for a substantial reduction in the radiation exposure and imaging time.

Axial volume scanning with iterative reconstruction at 320-row CT allows for a substantial reduction in the radiation exposure and imaging time and maintains the image quality in temporal bone CT.

Kitajima, M, Oda, S, Shigematsu, Y, Utsunomiya, D, Hirai, T, Yamashita, Y, Temporal Bone CT at 320-row CT: Effect of Axial Volume Scanning and the Iterative Reconstruction Algorithm on Image Quality and Radiation Exposure.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006867.html