title: Temporal Bone CT: Improved Image Quality and Potential for Decreased Radiation Dose Using an Ultra-High-Resolution Scan Mode with an Iterative Reconstruction Algorithm.
abstract: OBJECTIVE
  Radiation dose in temporal bone CT imaging can be high due to the requirement of high spatial resolution. In this study, we assessed whether CT imaging of the temporal bone by using an ultra-high-resolution scan mode combined with iterative reconstruction provides higher spatial resolution and lower image noise than a z-axis ultra-high-resolution mode.
  
  
  METHODS
  Patients with baseline temporal bone CT scans acquired by using a z-axis ultra-high-resolution protocol and a follow-up scan by using the ultra-high-resolution-iterative reconstruction technique were identified. Images of left and right temporal bones were reconstructed in the axial, coronal, and Poschl planes. Three neuroradiologists assessed the spatial resolution of the following structures: round and oval windows, incudomallear and incudostapedial joints, basal turn spiral lamina, and scutum. The paired z-axis ultra-high-resolution and ultra-high-resolution-iterative reconstruction images were displayed side by side in random order, with readers blinded to the imaging protocol. Image noise was compared in ROIs over the posterior fossa.
  
  
  RESULTS
  We identified 8 patients, yielding 16 sets of temporal bone images (left and right). Three sets were excluded because the patient underwent surgery between the 2 examinations. Spatial resolution was comparable (Poschl) or slightly better (axial and coronal planes) with ultra-high-resolution-iterative reconstruction than with z-axis ultra-high-resolution. A paired t test indicated that noise was significantly lower with ultra-high-resolution-iterative reconstruction than with z-axis ultra-high-resolution (P < .001), with a mean noise reduction of 37% (range, 18%-49%).
  
  
  CONCLUSIONS
  The ultra-high-resolution-iterative reconstruction scan mode has similar or slightly better resolution relative to the z-axis ultra-high-resolution mode for CT of the temporal bone but significantly (P < .01) lower image noise, which may enable the dose to be reduced by approximately 50%.
authors.affiliation: From the Departments of Radiology (S.L., F.E.D., J.I.L, K.K.K., R.J.W., C.H.M.) leng.shuai@mayo.edu.
authors.forename: S
authors.initials: S
authors.lastname: Leng
authors.affiliation: From the Departments of Radiology (S.L., F.E.D., J.I.L, K.K.K., R.J.W., C.H.M.).
authors.forename: F E
authors.initials: FE
authors.lastname: Diehn
authors.affiliation: From the Departments of Radiology (S.L., F.E.D., J.I.L, K.K.K., R.J.W., C.H.M.).
authors.forename: J I
authors.initials: JI
authors.lastname: Lane
authors.affiliation: From the Departments of Radiology (S.L., F.E.D., J.I.L, K.K.K., R.J.W., C.H.M.).
authors.forename: K K
authors.initials: KK
authors.lastname: Koeller
authors.affiliation: From the Departments of Radiology (S.L., F.E.D., J.I.L, K.K.K., R.J.W., C.H.M.).
authors.forename: R J
authors.initials: RJ
authors.lastname: Witte
authors.affiliation: Health Sciences Research, Division of Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, Rochester, Minnesota.
authors.forename: R E
authors.initials: RE
authors.lastname: Carter
authors.affiliation: From the Departments of Radiology (S.L., F.E.D., J.I.L, K.K.K., R.J.W., C.H.M.).
authors.forename: C H
authors.initials: CH
authors.lastname: McCollough
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D013701:Temporal Bone / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*