Efficiency of dual-energy computed tomography enterography in the diagnosis of Crohn’s disease

Background This retrospective study aimed to investigate the usefulness of the optimized kiloelectron volt (keV) for virtual monoenergetic imaging (VMI) combined with iodine map in dual-energy computed tomography enterography (DECTE) in the diagnosis of Crohn’s disease (CD). Methods Seventy-two patients (mean age: 41.89 ± 17.28 years) with negative computed tomography enterography (CTE) were enrolled for investigating the optimized VMI keV in DECTE by comparing subjective and objective parameters of VMIs that were reconstructed from 40 to 90 keV. Moreover, 68 patients (38.27 ± 15.10 years; 35 normal and 33 CD) were included for evaluating the diagnostic efficacy of DECTE iodine map at the optimized VMI energy level and routine CTE for CD and active CD. Statistical analysis for all data was conducted. Results Objective and subjective imaging evaluations showed the best results at 60 keV for VMIs. The CT values of the normal group, active subgroup, and CD group during the small intestinal phase at routine 120 kVp or 60 keV VMI had significant differences. The diagnostic efficacy of an iodine map was the best when NIC = 4% or fat value = 45.8% for CD, whereas NIC < 0.35 or the fat value < 0.38 for active CD. The combined routine CTE and optimized VMI improved the diagnostic efficacy (P < 0.001). Conclusions VMI at 60 keV provided the best imaging quality on DECTE. NIC and fat value provided important basis for active CD evaluation. Routine CTE combined with VMI at 60 keV improved the diagnostic efficiency for CD.

Feasibility of utilizing ultra-low-dose contrast medium for pancreatic artery depiction using the combination of advanced virtual monoenergetic imaging and high-concentration contrast medium: an intra-patient study

Objectives The least amount of contrast medium (CM) should be used under the premise of adequate diagnosis. The purpose of this study is to evaluate the feasibility of utilizing ultra-low-dose (224 mgI/kg) CM for pancreatic artery depiction using the combination of advanced virtual monoenergetic imaging (VMI+) and high-concentration (400 mgI/mL) CM. Materials and methods 41 patients who underwent both normal dose CM (ND-CM, 320 mgI/kg) and low dose CM (LD-CM, 224 mgI/kg) thoracoabdominal enhanced CT for tumor follow-up were prospectively included. The VMI+ at the energy level of 40-kev for LD-CM images was reconstructed. CT attenuation, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) of the abdominal artery, celiac artery, and superior mesenteric artery (SMA) and qualitative scores of pancreatic arteries depiction were recorded and compared among the three groups (ND-CM, LD-CM, and VMI+ LD-CM images). ANOVA and Friedman tests were used for statistical analysis. Results All quantitative and qualitative parameters on LD-CM images were lower than that on ND-CM images (all p < 0.01). There were no significant differences of all arteries’ qualitative scores between ND-CM and VMI+ LD-CM images (all p > 0.05). VMI+ LD-CM images had the highest mean CT and CNR values of all arteries (all p < 0.0001). The CM volume was 52.6 ± 9.4 mL for the ND-CM group and 37.0 ± 6.7 mL for the LD-CM group. Conclusion Ultra-low-dose CM (224 mgI/kg) was feasible for depicting pancreatic arteries. Inferior angiographic image quality could be successfully compensated by VMI+ and high-concentration CM.

Influence of beam hardening in dual-energy CT imaging: phantom study for iodine mapping, virtual monoenergetic imaging, and virtual non-contrast imaging

In this study, we investigated the influence of beam hardening on the dual-energy computed tomography (DECT) values of iodine maps, virtual monoenergetic (VME) images, and virtual non-contrast (VNC) images. 320-row DECT imaging was performed by changing the x-ray tube energy for the first and second rotations. DECT values of 5 mg/mL iodine of the multi-energy CT phantom were compared with and without a 2-mm-thick attenuation rubber layer (~700 HU) wound around the phantom. It was found that the CT density values UH, with/without the rubber layer had statistical differences in the iodine map (184 ± 0.7 versus 186 ± 1.8), VME images (125 ± 0.3 versus 110 ± 0.4), and VNC images (−58 ± 0.7 versus −76 ± 1.7) (p < 0.010 for all). This suggests that iodine mapping may be underestimated by DECT and overestimated by VME imaging because of x-ray beam hardening. The use of VNC images instead of plain CT images requires further investigation because of underestimation.

Visibility of bronchial arteries using virtual and advanced virtual monoenergetic imaging

Background The utility of virtual monoenergetic imaging (VMI) for fine arteries has not been well clarified. Purpose To assess bronchial artery visualization using VMI and noise-optimized advanced VMI (VMI+). Material and Methods Eighty-seven patients with esophageal cancer underwent computed tomography (CT) using a third-generation dual-source system before surgery. Tube voltages were set to 90 kVp and 150 kVp, respectively. Images were reconstructed using VMI and VMI+ with energy levels of 40–120 keV (in 10-keV increments); composite images equivalent to CT images at 105 kVp were also generated. The CT attenuation value and contrast-to-noise ratio (CNR) of bronchial arteries using VMI and VMI+ were compared with those obtained using composite imaging. Two radiologists subjectively analyzed bronchial artery visualization with reference to the composite image. Results CT attenuation values for bronchial arteries using VMI at 40–60 keV and VMI+ at 40 keV and 50 keV were significantly higher than those obtained using composite imaging ( P < 0.05). CNR using VMI at 40–60 keV was significantly higher than that obtained using composite imaging ( P < 0.05), whereas no differences were noted for values obtained using composite imaging between VMI+ at 40 keV and 50 keV. In the subjective analysis, VMI at 40 keV and 50 keV yielded significantly better visibility of bronchial arteries than VMI+ ( P < 0.05). Conclusion VMI and VMI+ at low voltages (40–50 keV) may be useful for bronchial artery visualization. VMI+ may be less effective for fine vessels as bronchial artery visualization.