OBJECTIVES: Energetic extrapolation is a promising strategy to reduce metal artifacts in dual-source computed tomography (DSCT). We performed this study to systematically optimize image acquisition parameters for this approach in a hip phantom and assess its value in a clinical study. MATERIALS AND METHODS: Titanium and steel hip prostheses were placed in a standard hip phantom and a water tank and scanned on a DSCT scanner. Tube spectra, tube current ratio, collimation, pitch, and rotation time were optimized in a stepwise process. Artifacts were quantified by measuring the standard deviation of the computed tomography density in a doughnut-shaped region of interest placed around the prosthesis. A total of 22 adult individuals with metallic implants referred for computed tomography for a musculoskeletal indication were scanned using the optimized protocol. Degree of artifacts and diagnostic image quality were rated visually (0-10) and maximum streak intensity was measured. RESULTS: Sn140/100 kVp proved superior to Sn140/80 kVp. There was a benefit for increasing tube current ratio from 1:1 to 3:1, but not beyond, in favor of the Sn140 kVp spectrum. Artifacts were less severe for a collimation of 32 × 0.6 mm as compared with 40 × 0.6 mm. A pitch of 0.5 at a rotation time of 0.5 seconds per rotation was preferable to other combinations with comparable scanning times. In the clinical study, increasing the extrapolated photon energy from 64 to 120 keV decreased the severity of artifacts from 8.0 to 2.0 (P < 0.001) and decreased streak intensity from 871 to 153 HU (P < 0.001). The median diagnostic image quality rating improved from 2.5 to 8.0 (P < 0.001). The median energy level visually perceived as optimal for diagnostic evaluation was 113 keV (range, 100-130 keV). CONCLUSIONS: Sn140/100 kVp with a tube current ratio of 3:1, a collimation of 32 × 0.6 mm, and extrapolated energies of 105 to 120 keV are optimal parameters for a dedicated DSCT protocol that effectively reduces metal artifacts by energetic extrapolation. The protocol effectively reduces metal artifacts in all types of metal implants. The optimized reconstructions yielded relevant additional findings.
OBJECTIVES: Energetic extrapolation is a promising strategy to reduce metal artifacts in dual-source computed tomography (DSCT). We performed this study to systematically optimize image acquisition parameters for this approach in a hip phantom and assess its value in a clinical study. MATERIALS AND METHODS: Titanium and steel hip prostheses were placed in a standard hip phantom and a water tank and scanned on a DSCT scanner. Tube spectra, tube current ratio, collimation, pitch, and rotation time were optimized in a stepwise process. Artifacts were quantified by measuring the standard deviation of the computed tomography density in a doughnut-shaped region of interest placed around the prosthesis. A total of 22 adult individuals with metallic implants referred for computed tomography for a musculoskeletal indication were scanned using the optimized protocol. Degree of artifacts and diagnostic image quality were rated visually (0-10) and maximum streak intensity was measured. RESULTS: Sn140/100 kVp proved superior to Sn140/80 kVp. There was a benefit for increasing tube current ratio from 1:1 to 3:1, but not beyond, in favor of the Sn140 kVp spectrum. Artifacts were less severe for a collimation of 32 × 0.6 mm as compared with 40 × 0.6 mm. A pitch of 0.5 at a rotation time of 0.5 seconds per rotation was preferable to other combinations with comparable scanning times. In the clinical study, increasing the extrapolated photon energy from 64 to 120 keV decreased the severity of artifacts from 8.0 to 2.0 (P < 0.001) and decreased streak intensity from 871 to 153 HU (P < 0.001). The median diagnostic image quality rating improved from 2.5 to 8.0 (P < 0.001). The median energy level visually perceived as optimal for diagnostic evaluation was 113 keV (range, 100-130 keV). CONCLUSIONS: Sn140/100 kVp with a tube current ratio of 3:1, a collimation of 32 × 0.6 mm, and extrapolated energies of 105 to 120 keV are optimal parameters for a dedicated DSCT protocol that effectively reduces metal artifacts by energetic extrapolation. The protocol effectively reduces metal artifacts in all types of metal implants. The optimized reconstructions yielded relevant additional findings.
Authors: Julian L Wichmann; Andrew D Hardie; U Joseph Schoepf; Lloyd M Felmly; Jonathan D Perry; Akos Varga-Szemes; Stefanie Mangold; Damiano Caruso; Christian Canstein; Thomas J Vogl; Carlo N De Cecco Journal: Eur Radiol Date: 2016-05-10 Impact factor: 5.315
Authors: Laura Filograna; Nicola Magarelli; Antonio Leone; Roman Guggenberger; Sebastian Winklhofer; Michael John Thali; Lorenzo Bonomo Journal: Skeletal Radiol Date: 2015-05-12 Impact factor: 2.199
Authors: Tommaso D'Angelo; Giuseppe Cicero; Silvio Mazziotti; Giorgio Ascenti; Moritz H Albrecht; Simon S Martin; Ahmed E Othman; Thomas J Vogl; Julian L Wichmann Journal: Br J Radiol Date: 2019-04-09 Impact factor: 3.039
Authors: Robert Forbrig; Lucas L Geyer; Robert Stahl; Jun Thorsteinsdottir; Christian Schichor; Friedrich-Wilhelm Kreth; Maximilian Patzig; Moriz Herzberg; Thomas Liebig; Franziska Dorn; Christoph G Trumm Journal: Eur Radiol Date: 2019-01-11 Impact factor: 5.315
Authors: Yothin Rakvongthai; William Worstell; Georges El Fakhri; Junguo Bian; Auranuch Lorsakul; Jinsong Ouyang Journal: IEEE Trans Med Imaging Date: 2014-09-19 Impact factor: 10.048
Authors: Tyler M Coupal; Paul I Mallinson; Patrick McLaughlin; Savvas Nicolaou; Peter L Munk; Hugue Ouellette Journal: Skeletal Radiol Date: 2014-01-17 Impact factor: 2.199
Authors: A L Kotsenas; G J Michalak; D R DeLone; F E Diehn; K Grant; A F Halaweish; A Krauss; R Raupach; B Schmidt; C H McCollough; J G Fletcher Journal: AJNR Am J Neuroradiol Date: 2015-08-06 Impact factor: 3.825