title: Validity of linear measurements of the jaws using ultralow-dose MDCT and the iterative techniques of ASIR and MBIR.
abstract: OBJECTIVE
  To assess the comparability of linear measurements of dental implant sites recorded from multidetector computed tomography (MDCT) images obtained using standard-dose filtered backprojection (FBP) technique with those from various ultralow doses combined with FBP, adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) techniques. The results of the study may contribute to MDCT dose optimization for dental implant site imaging.
  
  
  METHODS
  MDCT scans of two cadavers were acquired using a standard reference protocol and four ultralow-dose test protocols (TP). The volume CT dose index of the different dose protocols ranged from a maximum of 30.48-36.71 mGy to a minimum of 0.44-0.53 mGy. All scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Linear measurements were recorded from standardized images of the jaws by two examiners. Intra- and inter-examiner reliability of the measurements were analyzed using Cronbach's alpha and inter-item correlation. Agreement between the measurements obtained with the reference-dose/FBP protocol and each of the test protocols was determined with Bland-Altman plots and linear regression. Statistical significance was set at a P-value of 0.05.
  
  
  RESULTS
  No systematic variation was found between the linear measurements obtained with the reference protocol and the other imaging protocols. The only exceptions were TP3/ASIR-50 (bone kernel) and TP4/ASIR-100 (bone and standard kernels). The mean measurement differences between these three protocols and the reference protocol were within ±0.1 mm, with the 95 % confidence interval limits being within the range of ±1.15 mm.
  
  
  CONCLUSIONS
  A nearly 97.5 % reduction in dose did not significantly affect the height and width measurements of edentulous jaws regardless of the reconstruction algorithm used.
authors.affiliation: Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, P. O. Box 56810, Riyadh, 11564, Kingdom of Saudi Arabia. asma.alekrish@gmail.com.
authors.forename: Asma'a A
authors.initials: AA
authors.lastname: Al-Ekrish
authors.affiliation: Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, P. O. Box 56810, Riyadh, 11564, Kingdom of Saudi Arabia.
authors.forename: Reema
authors.initials: R
authors.lastname: Al-Shawaf
authors.affiliation: Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Schullian
authors.affiliation: Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, P. O. Box 56810, Riyadh, 11564, Kingdom of Saudi Arabia.
authors.forename: Ra'ed
authors.initials: R
authors.lastname: Al-Sadhan
authors.affiliation: Division of Clinical and Functional Anatomy, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Romed
authors.initials: R
authors.lastname: Hörmann
authors.affiliation: Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Gerlig
authors.initials: G
authors.lastname: Widmann
mesh_terms: D000465:Algorithms; D002102:Cadaver; D015921:Dental Implants; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007568:Jaw / Q000000981:diagnostic imaging*; D016014:Linear Models; D008962:Models, Theoretical; D061330:Multidetector Computed Tomography / Q000379:methods*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011877:Radionuclide Imaging; D015203:Reproducibility of Results
chemical_list: D015921:Dental Implants
keywords: Algorithms; Computer-assisted; Dental implants; Image processing; Multidetector computed tomography; Radiation dosage; Reproducibility of results