Gerlig Widmann1, Reema Al-Shawaf2, Peter Schullian1, Ra'ed Al-Sadhan2, Romed Hörmann3, Asma'a A Al-Ekrish4. 1. Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria. 2. Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, P. O. Box 56810, Riyadh, 11564, Kingdom of Saudi Arabia. 3. Division of Clinical and Functional Anatomy, Medical University of Innsbruck, Innsbruck, Austria. 4. 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.
Abstract
OBJECTIVES: Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. METHODS: Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. RESULTS: Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). CONCLUSIONS: Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. KEY POINTS: • Ultra-low-dose MDCT protocols allowed more than 90 % reductions in dose. • Decreasing the dose generally increased density and noise. • Effect of IRT on density and noise varies with reconstruction kernel. • Accuracy of low-dose protocols for interpretation of bony anatomy not known. • Effect of low doses on accuracy of computer-aided design models unknown.
OBJECTIVES: Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. METHODS: Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. RESULTS: Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). CONCLUSIONS: Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. KEY POINTS: • Ultra-low-dose MDCT protocols allowed more than 90 % reductions in dose. • Decreasing the dose generally increased density and noise. • Effect of IRT on density and noise varies with reconstruction kernel. • Accuracy of low-dose protocols for interpretation of bony anatomy not known. • Effect of low doses on accuracy of computer-aided design models unknown.
Authors: Stefan B Puchner; Maros Ferencik; Pal Maurovich-Horvat; Masataka Nakano; Fumiyuki Otsuka; Hans-Ulrich Kauczor; Renu Virmani; Udo Hoffmann; Christopher L Schlett Journal: Eur Radiol Date: 2014-09-03 Impact factor: 5.315