title: Ultralow-dose CT of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction and model-based iterative reconstruction: 2D and 3D image quality.
abstract: OBJECTIVE. The purpose of this article is to evaluate 2D and 3D image quality of high-resolution ultralow-dose CT images of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) in comparison with standard filtered backprojection (FBP). MATERIALS AND METHODS. A formalin-fixed human cadaver head was scanned using a clinical reference protocol at a CT dose index volume of 30.48 mGy and a series of five ultralow-dose protocols at 3.48, 2.19, 0.82, 0.44, and 0.22 mGy using FBP and ASIR at 50% (ASIR-50), ASIR at 100% (ASIR-100), and MBIR. Blinded 2D axial and 3D volume-rendered images were compared with each other by three readers using top-down scoring. Scores were analyzed per protocol or dose and reconstruction. All images were compared with the FBP reference at 30.48 mGy. A nonparametric Mann-Whitney U test was used. Statistical significance was set at p < 0.05. RESULTS. For 2D images, the FBP reference at 30.48 mGy did not statistically significantly differ from ASIR-100 at 3.48 mGy, ASIR-100 at 2.19 mGy, and MBIR at 0.82 mGy. MBIR at 2.19 and 3.48 mGy scored statistically significantly better than the FBP reference (p = 0.032 and 0.001, respectively). For 3D images, the FBP reference at 30.48 mGy did not statistically significantly differ from all reconstructions at 3.48 mGy; FBP and ASIR-100 at 2.19 mGy; FBP, ASIR-100, and MBIR at 0.82 mGy; MBIR at 0.44 mGy; and MBIR at 0.22 mGy. CONCLUSION. MBIR (2D and 3D) and ASIR-100 (2D) may significantly improve subjective image quality of ultralow-dose images and may allow more than 90% dose reductions.
authors.affiliation: 1 Department of Radiology, Innsbruck Medical University, Anichstrasse 35, Innsbruck A-6020, Austria.
authors.forename: Gerlig
authors.initials: G
authors.lastname: Widmann
authors.forename: Peter
authors.initials: P
authors.lastname: Schullian
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Gassner
authors.forename: Romed
authors.initials: R
authors.lastname: Hoermann
authors.forename: Reto
authors.initials: R
authors.lastname: Bale
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Puelacher
mesh_terms: D002102:Cadaver; D005147:Facial Bones / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008962:Models, Theoretical; D011829:Radiation Dosage; D012886:Skull / Q000000981:diagnostic imaging* / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: adaptive statistical iterative reconstruction; image quality; maxillofacial bone; model-based iterative reconstruction; ultralow-dose CT