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Objective To investigate the application value of spectral computed tomography venography(CTV)in the display and staging of deep venous thrombosis(DVT)in the lower extremity.Methods Eighty-two patients with CTV were selected and ran-domly divided into group A(42 patients)and group B(40 patients).Group A:tube voltage 120 kVp.Group B:gemstone spectral ima-ging(GSI)mode,reconstruction of 50 keV and iodine(water)maps.The CT and standard deviation(SD)values of the veins were measured,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)were calculated in 120 kVp images of group A and in 50 keV images of group B.Two observers scored the image quality of the 2 groups subjectively,and Kappa test was used to examine the con-sistency.Based on the duration from the occurrence of clinical symptoms,the DVTs were classified.The CT values and iodine con-centration(IC)of DVT were measured in the 120 kVp images of group A and in the iodine(water)maps of group B,respectively.The receiver operating characteristic(ROC)curve was drawn to compare the effectiveness of CT values and IC in diagnosing DVT staging.Results CT values,SNR,and CNR of veins in group B were higher than those in group A(P<0.05).The subjective scores of the two groups were consistent(Kappa=0.926-0.955,P<0.05).The score for the display of veins and thrombus clarity in group B was 5(4,5),which was better than the score of 4(3,4)in group A(P<0.05).The efficiency of IC in diagnosing DVT staging[area under the curve(AUC)=0.973]was better than that of CT values(AUC=0.891).Conclusion The spectral CTV can improve the contrast of lower extremity deep veins and the clarity of thrombus,and can provide more objective indicators for the diagnosis of thrombus staging,which is conducive to accurate clinical diagnosis and treatment.
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Objective:To investigate the value of the virtual monoenergetic image (VMI) obtained by a new dual-layer detector spectral CT combined with metal artifact reduction algorithms(O-MAR) in reduction of different types of artifacts caused by 125I seeds implantation and in improvement of the post-operative CT image quality. Methods:This was a cross-sectional study. Thirty-five patients who underwent dual-layer detector spectral CT scanning of the chest and abdomen after 125I seeds implantation were retrospectively included at the First Affiliated Hospital of Zhengzhou University from March to September 2022. The spectral data were collected and reconstructed into conventional CT image (CI), VMI image (50-150 keV, 20 keV/level), CI+O-MAR image, and VMI+O-MAR image (50-150 keV, 20 keV/level). The artifacts′ removal effects and image quality improvement in each group were evaluated. Two slices with the strongest artifacts were selected for analysis for each patient, resulting in a total of 70 slices. Objective indicators including artifact index (AI), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of soft tissue regions affected by artifacts were measured and calculated. Subjective indicators including the overcorrected artifacts and new artifacts, the different forms of artifacts, the diagnosis of artifacts, and the image quality were assessed. One-way analysis of variance was used for comparisons among multiple groups. Paired t test was used to compare the quantitative indicators between the combined O-MAR group and the non-O-MAR group. Kappa statistics was used to evaluate the consistency between observers. Results:In high/low-density artifacts (ROI H/L), the AI values in all groups showed decrease with increasing VMI keV. In artifact-affected tissue (ROI T), SNR of the CI/VMI (70-150 keV)+O-MAR group were significantly higher than those of the CI/VMI group ( P<0.05), CNR of the CI/VMI(50-150 keV)+O-MAR group were significantly higher than those of the CI/VMI group ( P<0.05). Both overcorrection and new artifacts mainly presented in VMI 50 keV and VMI 70 keV groups; Compared with VMI (50-70 keV) group, significantly less numbers of overcorrection and new artifacts were found in VMI (50-70 keV)+O-MAR group ( P<0.05); regarding the comparison of artifact types, with the VMI keV increasing, the number of a-type banded artifacts gradually decreased on images with high-density artifacts, reaching a minimum of 3 in the VMI 150 keV+O-MAR group; while the number of e-type artifacts with little or no artifacts increased, with the highest number of 23 in the VMI 150 keV+O-MAR group. The total number of high-density artifacts in each type decreased with increasing VMI keV. As VMI keV increased, the diagnostic and image quality scores of high-density artifacts in each group were significantly higher than those of low-density artifacts in the VMI+O-MAR group ( P<0.05). Conclusions:VMI combined with O-MAR can significantly improve the objective and subjective image quality of follow-up CT imaging after 125I seed implantation, enhancing lesion visibility and diagnostic confidence. Additionally, VMI+O-MAR showed more pronounced correction effect on high-density artifacts.
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Objective:To evaluate spectral CT metal artifacts reduction (MAR) technique in reducing metal artifacts of spinal implants in a phantom.Methods:Ovine spines were chosen as anthropomorphic phantom. The phantom including the pedicle screws, 3D-printed vertebral body (VB) and mesh cage were examined using spectral CT. Postoperative CT images were reconstructed at 70—140 keV with 10 keV interval of MAR and non-MAR. Artifact index (AI) and signal-to-noise ratio (SNR) were evaluated by CT and SD values in ROIs around the implants. Visibility of bony structures, the artifacts of pedicle screw, 3D-printed VB and mesh cage were subjectively evaluated. Plotting curves of AI and SNR with the increasing keV were drawn. The AI and SNR were compared at lower (70 keV), medium (100 keV) and high (130 keV) level between MAR and non-MAR images using the paired t-test, and the subjective scores were compared using Wilcoxon signed rank-sum test. Results:The AI values around pedicle screws (anterior, posterior and lateral), 3D-printed VB and mesh cage decreased with the increase of keV, while SNR improved in MAR and non-MAR images. The AI values in the anterior, lateral and posterior pedicle screws and lateral titanium implants were significantly lower in MAR than those in non-MAR ( P<0.05). The AI value in posterior 3D-printed vertebral was lower in MAR than that of non-MAR only at 70 keV ( P<0.001). The SNR values in the anterior and posterior pedicle screws, 3D-printed VB increased with the increase of keV, but decreased in other ROIs. In the subjective evaluation, the image scores of MAR were higher than those of non-MAR ( P<0.05). Conclusion:Spectral CT using the MAR reconstruction can effectively reduce metal artifacts of spinal implants. The effect is better in pedicle screw and mesh cage than 3D-printed VB.
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The progress of the gemstone spectral CT was introduced in clinical application. Review was executed from the aspects of energy spectrum technique and clinical application. The clinical application of the gemstone spectral CT was discussed in monochromatic imaging, materials decomposition, spectral curve, effective atomic number and analysis tool of the energy spectrum technique as well as in its clinical application to head, neck, chest, abdomen, musculoskeletal system and etc. Gemstone spectral CT could implement multi-parameter imaging and data analysis with analysis platform and tools and facilitate the qualitative and location diagnoses as well as treatment planning of the diseases, and thus could be promoted for comprehensive diagnosis, differential diagnosis, location diagnosis, postoperative imaging of iatrogenic metal implants, angiography, analysis on stone composition and etc of the tumors.