Beam-hardening in 70-kV Coronary CT angiography: Artifact reduction using an advanced post-processing algorithm

Can the Coronary Artery Calcium Score Scan Reduce the Radiation Dose in Coronary Computed Tomography Angiography?

RATIONALE AND OBJECTIVES

Radiation exposure from coronary computed tomography angiography (CCTA) remains a cause for concern. The objective of this study was to investigate whether using the coronary artery calcium score scan (CACS) would reduce the radiation dose for CCTA scanning and the overall radiation exposure (ORE).

MATERIALS AND METHODS

In total, 256 patients were examined with a third-generation dual-source CT (n = 200) or 256-row CT (n = 56), among whom 105 (Group A) and 28 patients (Group B), respectively, underwent CCTA with CACS for field of view planning. The remaining patients, with the scout view for field of view planning, constituted Group A1 and B1. The scanning parameter settings were standardized between groups.

RESULTS

Shorter scan lengths were observed in Group A (9.98 ± 0.79 cm) compared to Group A1 (13.64 ± 1.79 cm; p < 0.001), which also resulted in a lower dose-length product (DLP) in Group A (115.04 ± 64.13) relative to Group A1 (138.67 ± 68.87; p < 0.05). Similarly, shorter scan lengths were found in Group B (14.92 ± 1.17 cm) compared to Group B1 (15.79 ± 0.63 cm; p = 0.001); this resulted in a lower DLP (322.07 ± 45.39) compared to Group B1 (354.34 ± 65.27; p = 0.036). The CACS resulted in an increase in ORE in both groups.

CONCLUSION

CACS may have a critical role in the reduction of radiation dose in CCTA scanning, but the potential effectiveness of CACS in reducing ORE is weak.

Effectiveness of Commercial Software-Enhanced Image Artifact Reduction Software

INTRODUCTION

Artifact reduction (AR) software has been incorporated into some cone-beam computed tomographic (CBCT) systems to reduce the severity of beam hardening (BH) artifacts and improve image quality. This study quantifies BH artifact and evaluates the effectiveness of AR in 2 CBCT systems.

METHODS

Palatal roots of Dent-Alike (Dentsply Sirona, Tulsa, OK) teeth were prepared and root filled with gutta-percha and EndoSequence BC Sealer (Brasseler, Savannah, GA). Six teeth were imaged with and without AR software using the ProMax3D (Planmeca Oy, Helsinki, Finland) and the Pax-i3D (Vatech, Hwaseong-si, South Korea) systems. FSL (FMRIB, Oxford, UK) software was used to quantify the light and dark components of the BH artifact along the tooth root using a specific region of interest approach and an image-wide analysis approach. Statistical analysis was performed using paired t tests and corrected for multiple comparisons with cluster mass correction using a nonparametric statistical analysis to evaluate the differences in the artifact volumes and areas with and without AR.

RESULTS

A significant reduction in the light artifact was observed with the Planmeca system (P < .05), but no significant differences were observed for either the light or dark artifacts with the Vatech system when AR was applied. There were also significant reductions in the volumes of light and dark artifacts along the entire root length when the AR was applied with the Planmeca system (cluster mass P < .05), but no significant differences were observed with the Vatech system.

CONCLUSIONS

Proprietary AR software is not equally effective in reducing the light and/or dark components of CBCT BH artifacts.

Non-invasive imaging techniques to assess myocardial perfusion

INTRODUCTION

Coronary artery disease affecting myocardial perfusion continues to be the leading cause of cardiovascular morbidity and mortality worldwide. While invasive evaluation based on coronary angiography and flow measurements still is considered the reference technique for assessing myocardial perfusion, technological evolutions in noninvasive imaging techniques resulted in them playing a more important role in assessing myocardial perfusion influencing therapeutic decision-making and prognostication.

AREAS COVERED

Different imaging modalities are used to evaluate coronary perfusion, including echocardiography, coronary computerized tomography scan, magnetic resonance imaging, and nuclear myocardial perfusion imaging. Through a combination of different techniques, it is possible to describe coronary artery anatomy and the diameter of the epicardial vessels but more recently also of the coronary microcirculation. Quantification of myocardial perfusion is feasible both at baseline and during pharmacological or physiological stress.

EXPERT OPINION

The objective of this state-of-the-art paper is to review the recent evolutions in imaging methods to estimate myocardial perfusion and to discuss the diagnostic strengths and limitations of the different techniques. The new ultrasound technologies and the hybrid approaches seem to be the future is these fields.

CT artifacts from port systems: Virtual monoenergetic reconstructions from spectral-detector CT reduce artifacts and improve depiction of surrounding tissue

PURPOSE

CT artifacts from port-systems are a common problem in staging- and restaging-examinations and reduce image quality and diagnostic assessment. The purpose of this study was to investigate the reduction of these artifacts using virtual monoenergetic images (VMI) from dual-energy spectral-detector CT (SDCT) in comparison to conventional CT-images (CI).

METHOD

50 SDCT-datasets of patients with artifacts from port-chamber and port-catheters were included in this IRB-approved, retrospective study. CI and VMI (range, 40-200 keV, 10 keV increment) were reconstructed from the same acquisition. The quantitative image analysis was performed ROI-based assessing mean and standard deviation of attenuation (HU) in most pronounced hypo- and hyperdense artifacts surrounding to the port-chamber and the distal end of the port-catheter in the superior vena cava. Subjectively, artifact reduction and diagnostic assessment of surrounding soft tissue were rated on 5-point Likert-scales.

RESULTS

In comparison to CI, VMI of higher keV-values showed strong reduction of hypo- and hyperattenuating artifacts around the port-chamber and port-catheter (CI/VMI_200keV: hypodense -104.7 ± 124.7HU/10.8 ± 58.1HU and -101.6 ± 101.5HU/-36.7 ± 32.9HU; hyperdense 240.8 ± 151.6HU/79.6 ± 81.3HU and 108.6 ± 129.3HU/25.9 ± 31.9HU; all p < 0.001). Image noise could also be reduced significantly. The subjective analysis showed significantly reduced artifacts around the port-chamber and port-catheter (CI/VMI_200keV: hypodense 3(1-4)/5(4-5) and 3(2-4)/5(4-5); hyperdense 3(1-4)/5(4-5) and 3(2-3)/5(3-5); all p < 0.001) and improved diagnostic assessment of pectoral/subclavian soft tissue for VMI of ≥100keV. Ratings for diagnostic assessment were best between 140-200 keV. Overall interrater agreement was high (ICC = 0.79).

CONCLUSIONS

Higher keV VMI enabled a significant reduction of artifacts from port-systems around the chamber and the catheter leading to improved assessment of surrounding soft tissue.