Gerlig Widmann1, Alexander Bischel2, Andreas Stratis3, Hilde Bosmans3, Reinhilde Jacobs3, Eva-Maria Gassner1, Wolfgang Puelacher2, Ruben Pauwels3,4. 1. 1 Department of Radiology, Innsbruck Medical University, Innsbruck, Austria. 2. 2 Department of Craniomaxillofacial Surgery, Innsbruck Medical University, Innsbruck, Austria. 3. 3 Department of Imaging and Pathology, OMFS-IMPATH Research Group, KU Leuven-Group Biomedical Sciences Oral and Maxillofacial Surgery-UZ Leuven, Leuven, Belgium. 4. 4 Department of Radiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Abstract
OBJECTIVES: The objective of this study was to determine how iterative reconstruction technology (IRT) influences contrast and spatial resolution in ultralow-dose dentomaxillofacial CT imaging. METHODS: A polymethyl methacrylate phantom with various inserts was scanned using a reference protocol (RP) at CT dose index volume 36.56 mGy, a sinus protocol at 18.28 mGy and ultralow-dose protocols (LD) at 4.17 mGy, 2.36 mGy, 0.99 mGy and 0.53 mGy. All data sets were reconstructed using filtered back projection (FBP) and the following IRTs: adaptive statistical iterative reconstructions (ASIRs) (ASIR-50, ASIR-100) and model-based iterative reconstruction (MBIR). Inserts containing line-pair patterns and contrast detail patterns for three different materials were scored by three observers. Observer agreement was analyzed using Cohen's kappa and difference in performance between the protocols and reconstruction was analyzed with Dunn's test at α = 0.05. RESULTS: Interobserver agreement was acceptable with a mean kappa value of 0.59. Compared with the RP using FBP, similar scores were achieved at 2.36 mGy using MBIR. MIBR reconstructions showed the highest noise suppression as well as good contrast even at the lowest doses. Overall, ASIR reconstructions did not outperform FBP. CONCLUSIONS: LD and MBIR at a dose reduction of >90% may show no significant differences in spatial and contrast resolution compared with an RP and FBP. Ultralow-dose CT and IRT should be further explored in clinical studies.
OBJECTIVES: The objective of this study was to determine how iterative reconstruction technology (IRT) influences contrast and spatial resolution in ultralow-dose dentomaxillofacial CT imaging. METHODS: A polymethyl methacrylate phantom with various inserts was scanned using a reference protocol (RP) at CT dose index volume 36.56 mGy, a sinus protocol at 18.28 mGy and ultralow-dose protocols (LD) at 4.17 mGy, 2.36 mGy, 0.99 mGy and 0.53 mGy. All data sets were reconstructed using filtered back projection (FBP) and the following IRTs: adaptive statistical iterative reconstructions (ASIRs) (ASIR-50, ASIR-100) and model-based iterative reconstruction (MBIR). Inserts containing line-pair patterns and contrast detail patterns for three different materials were scored by three observers. Observer agreement was analyzed using Cohen's kappa and difference in performance between the protocols and reconstruction was analyzed with Dunn's test at α = 0.05. RESULTS: Interobserver agreement was acceptable with a mean kappa value of 0.59. Compared with the RP using FBP, similar scores were achieved at 2.36 mGy using MBIR. MIBR reconstructions showed the highest noise suppression as well as good contrast even at the lowest doses. Overall, ASIR reconstructions did not outperform FBP. CONCLUSIONS: LD and MBIR at a dose reduction of >90% may show no significant differences in spatial and contrast resolution compared with an RP and FBP. Ultralow-dose CT and IRT should be further explored in clinical studies.
Authors: R Pauwels; O Nackaerts; N Bellaiche; H Stamatakis; K Tsiklakis; A Walker; H Bosmans; R Bogaerts; R Jacobs; K Horner Journal: Br J Radiol Date: 2013-01 Impact factor: 3.039