Technical performance of a dual‐energy CT system with a novel deep‐learning based reconstruction process: Evaluation using an abdomen protocol

Abstract

Background: A new tube voltage-switching dual-energy (DE) CT system using a novel deep-learning based reconstruction process has been introduced. Characterizing the performance of this DE approach can help demonstrate its benefits and potential drawbacks. Purpose: To evaluate the technical performance of a novel DECT system and compare it to that of standard single-kV CT and a rotate/rotate DECT, for abdominal imaging. Methods: DE and single-kV images of four different phantoms were acquired on a kV-switching DECT system, and on a rotate/rotate DECT. The dose for the acquisitions of each phantom was set to that selected for the kV-switching DE mode by the automatic tube current modulation (ATCM) at manufacturerrecommended settings. The dose that the ATCM would have selected in single-kV mode was also recorded. Virtual monochromatic images (VMIs) from 40 to 130 keV, as well as iodine maps, were reconstructed from the DE data. Single-kV images, acquired at 120 kV, were reconstructed using body hybrid iterative reconstruction. All reconstructions were made at 0.5 mm section thickness. Task transfer functions (TTFs) were determined for a Teflon and LDPE rod. Noise magnitude (SD), and noise power spectrum (NPS) were calculated using 240 and 320 mm diameter water phantoms. Iodine quantification accuracy and contrast-to-noise ratios (CNRs) relative to water for 2, 5, 10, and 15 mg I/ml were determined using a multi-energy CT (MECT) phantom. Low-contrast visibility was determined and the presence of beam-hardening artifacts and inhomogeneities were evaluated. Results:The TTFs of the kV-switching DE VMIs were higher than that of the single-kV images for Teflon (20% TTF: 6.8 lp/cm at 40 keV, 6.2 lp/cm for single-kV), while for LDPE the DE TTFs at 70 keV and above were equivalent or higher than the single-kV TTF. All TTFs of the kV-switching DECT were higher than for the rotate/rotate DECT. The SD was lowest in the 70 keV VMI (12.0 HU), which was lower than that of single-kV (18.3 HU). The average NPS frequency varied between 2.3 lp/cm and 4.2 lp/cm for the kV-switching VMIs and was 2.2 lp/cm for single-kV. The error in iodine quantification was at maximum 1 mg I/ml (at 5 mg I/ml). The highest CNR for all iodine concentrations was at 60 keV, 2.5 times higher than the CNR for single-kV. At 70-90 keV, the number of visible low contrast objects was comparable to that in single-kV, while other VMIs showedThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Study of radiomics based on dual-energy CT for nuclear grading and T-staging in renal clear cell carcinoma

“…[24] With the increase of energy, the diagnostic accuracy of renal lesions could decrease, 70 KeV VMI has the lowest noise magnitude and may provide the best trade-off between sensitivity and specificity. [30,31] Some studies considered 70 KeV VMI accepted as a relatively standard energy level for routine reconstruction. [24] In this study, the radiomics models for nuclear grading and T-staging based on different VMI, IMDI, and MEI images obtained a certain value, The radomics model based on VMI obtained better results than MEI model.…”

“…[ 24 ] With the increase of energy, the diagnostic accuracy of renal lesions could decrease, 70 KeV VMI has the lowest noise magnitude and may provide the best trade-off between sensitivity and specificity. [ 30 , 31 ] Some studies considered 70 KeV VMI accepted as a relatively standard energy level for routine reconstruction. [ 24 ]…”

Spectral performance of two split‐filter dual‐energy CT systems: A phantom study

“…[1][2][3][4][5] With abdominal CT imaging, lowenergy level virtual monoenergetic images (VMIs) are used to enhance the contrast of lesions and iodine maps to quantify the concentration of iodine in lesions. [5][6][7][8][9][10] Both types of images improve the detection and characterization of lesions, particularly in the liver, kidney, and adrenals. 5,7,11,12 Many dual-energy CT (DECT) platforms have been developed to obtain both the low-and high-energy photon spectra required to create spectral images.…”

“…Different types of spectral images can help radiologists in their interpretation 1–5 . With abdominal CT imaging, low‐energy level virtual monoenergetic images (VMIs) are used to enhance the contrast of lesions and iodine maps to quantify the concentration of iodine in lesions 5–10 . Both types of images improve the detection and characterization of lesions, particularly in the liver, kidney, and adrenals 5,7,11,12 …”