Discovery CT750 HD Research Articles

The utility of virtual monochromatic dual-energy computed tomography (DECT) in meniscal imaging: a technical evaluation.

To determine the feasibility of meniscal imaging using virtual monochromatic images obtained through dualenergy computed tomography (DECT) technique, and to determine which keV levels optimise contrast resolution. All DECT exams were performed on a Discovery CT750 HD system from GE Healthcare. Virtual monochromatic images were reconstructed at 40 keV, 73 keV, 106 keV, and 139 keV. Contrast resolution of the medial and lateral menisci using a 5-point Likert scale at each keV level was determined through a consensus agreement by 2 fellowship-trained musculoskeletal radiologists. Friedman's and Wilcoxon signed rank tests were used to compare visualisation scores across different keV levels. Seventeen knee exams from 10 patients met criteria for inclusion in the study. All patients included in the study cohort were male. The median age of patients was 46 years (interquartile range, 35-53 years). Virtual monochromatic images at 40 keV demonstrated highest contrast resolution of the menisci, with a statistically significant difference between contrast resolution scores at 40 keV and 76 keV, Friedman test: p < 0.0001. Meniscal imaging is feasible using DECT virtual monochromatic images at low keV levels. Improved contrast resolution at these specified KeV values could pave the way for further research in this field to determine its role in the future as an alternative option for assessment of the menisci in patients with contraindications to MRI or in the setting of a periarticular ferromagnetic foreign body obscuring the field of view.

Optimization of wrist tendon detection in virtual monochromatic images using dual energy-computed tomography.

To evaluate the depiction of wrist tendons in virtual monochromatic images (VMIs) during a dual-energy CT (DE-CT) with the VMI image of conventional equivalent to 120kVp. Using Catphan600 and phantom analysis software for CT evaluation, measurements of VMI in a DE-CT were performed corresponding to the tube voltages of single-energy CT at 120kVp. Using a Discovery CT750 HD CT scanner (GE Healthcare) with DE-CT technology, 73 patients were scanned. We calculated the CT number, image noise, visual score, and contrast noise ratio (CNR) at the extensor pollicis tendon, extensor digitorum tendon, and flexor tendon in 11 VMIs from the DE-CT and VMI image of conventional equivalent to 120kVp. The results from the optimal VMIs were then compared with that of the VMI image of the conventional equivalent to 120kVp. The highest CT number and CNR for the tendon were for the 140keV VMI in the DE-CT compared to the other energy levels. There were significantly higher CT numbers, CNR values, and visual scores for each tendon at 140keV VMI with the DE-CT (p < 0.01) compared with a VMI image of conventional equivalent to 120kVp. Energy level of the VMIs during DE-CT for the best wrist tendon delineation was 140keV. This value of 140keV for the DE-CT was significantly higher than the CT number and CNR for the extensor pollicis, extensor digitorum, and flexor tendon compared with a VMI image of conventional equivalent to 120kVp.

Comparison of image quality, arterial depiction, and radiation dose between two rapid kVp-switching dual-energy CT scanners in CT angiography at 40-keV

PurposeTo compare the quantitative parameters and qualitative image quality of dual-energy CT angiography (CTA) between two rapid kVp-switching dual-energy CT scanners.Materials and methodsBetween May 2021 and March 2022, 79 participants underwent whole-body CTA using either Discovery CT750 HD (Group A, n = 38) or Revolution CT Apex (Group B, n = 41). All data were reconstructed at 40-keV and with adaptive statistical iterative reconstruction-Veo of 40%. The two groups were compared in terms of CT numbers of the thoracic and abdominal aorta, and the iliac artery, background noise, signal-to-noise ratio (SNR) of the artery, CT dose-index volume (CTDIvol), and qualitative scores for image noise, sharpness, diagnostic acceptability, and arterial depictions.ResultsThe median CT number of the abdominal aorta (p = 0.04) and SNR of the thoracic aorta (p = 0.02) were higher in Group B than in Group A, while no difference was observed in the other CT numbers and SNRs of the artery (p = 0.09–0.23). The background noises at the thoracic (p = 0.11), abdominal (p = 0.85), and pelvic (p = 0.85) regions were comparable between the two groups. CTDIvol was lower in Group B than in Group A (p = 0.006). All qualitative scores were higher in Group B than in Group A (p < 0.001–0.04). The arterial depictions were nearly identical in both two groups (p = 0.005–1.0).ConclusionIn dual-energy CTA at 40-keV, Revolution CT Apex improved qualitative image quality and reduced radiation dose.

The Impacts of Vertical Off-Centring, Localiser Direction, Phantom Positioning and Tube Voltage on CT Number Accuracy: An Experimental Study.

Background: This study investigates the effects of vertical off-centring, localiser direction, tube voltage, and phantom positioning (supine and prone) on computed tomography (CT) numbers and radiation dose. Methods: An anthropomorphic phantom was scanned using a Discovery CT750 HD—128 slice (GE Healthcare) scanner at different tube voltages (80, 120, and 140 kVp). Images employing 0° and 180° localisers were acquired in supine and prone positions for each vertical off-centring (±100, ±60, and ±30 mm from the iso-centre). CT numbers and displayed volume CT dose index (CTDIvol) were recorded. The relationship between dose variation and CT number was investigated. Results: The maximum changes in CT number between the two phantom positions as a function of vertical-off-centring were for the upper thorax 34 HU (0° localiser, 120 kVp), mid thorax 43 HU (180° localiser, 80 kVp), and for the abdominal section 31 HU (0° localiser, 80 kVp) in the prone position. A strong positive correlation was reported between the variation in dose and CT number (r = 0.969, p < 0.001); 95% CI (0.93, 0.99). Conclusions: Patient positioning demands an approach with a high degree of accuracy, especially in cases where clinical decisions depend on CT number accuracy for tissue lesion characterisation.

Quality Assessment of Mobile Cone-beam Computerized Tomography Scanner Made in Thailand: A Phantom Study

Background: In 2011, the National Science and Technology Development Agency had successfully developed the first local-made mobile conebeam computed tomography (CBCT) scanner, called MobiiScan. Before a computed tomography (CT) scanner can be used in clinical practice, it must pass a quality assurance process. Objective: To assess the performance of MobiiScan before it can be further evaluated in human subjects. Materials and Methods: Images from scanning of an imaging phantom by MobiiScan were compared to a commercial 64-slice (GE Discovery CT750 HD) and a mobile (Neurologica CereTom) CT scanner, which were used as controls. Spatial resolution, uniformity, noise, accuracy of CT number, and geometric accuracy were examined by three investigators. Results: According to the bone scanning protocol, spatial resolution of the images produced by MobiiScan was comparable to the mobile scanner, but it was less than the 64-slice scanner. In addition, the signal uniformity of MobiiScan was poorer compared to the controls. MobiiScan produced more noise than the mobile and the 64-slice scanners at the 120-kVp mode, but less noise than the 64-slice scanner at the 80-kVp mode. Using the brain protocol, the spatial resolution from the MobiiScan was higher than the mobile scanner, but comparable to the 64-slice scanner. Although the signal uniformity of the MobiiScan was superior compared to the controls, the noise production was more than the controls. At all settings, the MobiiScan gave underrated distances and inaccurate CT numbers. However, it delivered very low radiation doses. Conclusion: MobiiScan had a good spatial resolution and delivered low radiation dose, which suggested that it could be used for bone examination as intended by the creator. However, its noise production and inaccurate CT numbers suggest that MobiiScan should not be used to diagnose soft tissue problems. It is recommended that the hardware and software should be adjusted to provide a better signal uniformity, lower noise level, accurate CT number, and geometric accuracy. Keywords: X-ray computed tomography; Cone-beam computed tomography; Craniofacial abnormalities; Radiologic phantom; MobiiScan

0° vs. 180° CT localiser: The effect of vertical off-centring, phantom positioning and tube voltage on dose optimisation in multidetector computed tomography.

IntroductionPatient positioning is an essential consideration for the optimisation of radiation dose during CT examinations. The study objectives seek to explore the effects of vertical off‐centring, localiser direction (0° and 180°), and phantom positioning (supine and prone) on radiation dose, using three different tube voltages in multidetector computed tomography (MDCT) imaging.MethodsThe trunk of a PBU‐60 anthropomorphic phantom was imaged using a Discovery CT750 HD – 128 slice (GE Healthcare). Images employing 0° and 180° localisers were acquired in supine and prone orientation for each combination of vertical off‐centring (±100, ±60 and ±30 mm) and different tube voltages (80, 120 and 140 kVp), using the system’s automatic tube current modulation (ATCM) function. The displayed volume CT dose index (CTDIvol) and dose length product (DLP) were recorded.ResultsWith incremental table off‐centring of ±100 mm, the dose at 120 kVp in the supine position ranged from 63% to 196% (0° localiser) and from 66% to 191% (180° localiser) as compared to iso‐centre. While in the prone position, the dose ranged from 62% to 195% (0° localiser); and 62% to 193% (180° localiser), with a notable dose increase at higher tube voltages. Dose variation and vertical off‐centring showed a significant relationship for both 0° and 180° localisers (r = 0.94 and 0.96, respectively, P < 0.001). The CTDIvol variation between supine and prone phantom positions at ±100 mm off‐centring was 0.22 mGy (2.9%), and 0.19 mGy (2.3%) when the 0° and 180 ° localisers were utilised, respectively.ConclusionsPhantom off‐centring and localiser direction evidenced large dose variation. It is recommended that the 0° localiser is employed during CT examinations, in order to minimise the potential additional radiation dose which may result from off‐centring and the use of lower tube voltages where clinically appropriate.

Two-year reduction of dual-energy CT urate depositions during a treat-to-target strategy in gout in the NOR-Gout longitudinal study.

ObjectivesThere is a lack of large longitudinal studies of urate deposition measured by dual-energy CT (DECT) during urate lowering therapy (ULT) in people with gout. We explored longitudinal changes in DECT urate depositions during a treat-to-target strategy with ULT in gout.MethodsPatients with a recent gout flare and serum-urate (sUA) >360 µmol/l attended tight-control visits during escalating ULT. The treatment target was sUA <360 µmol/l, and <300 µmol/l if presence of tophi. A DECT scanner (General Electric Discovery CT750 HD) acquired data from bilateral forefeet and ankles at baseline and after one and two years. Images were scored in known order, using the semi-quantitative Bayat method, by one experienced radiologist who was blinded to serum urate and clinical data. Four regions were scored: the first metatarsophalangeal (MTP1) joint, the other joints of the toes, the ankles and midfeet, and all tendons in the feet and ankles.ResultsDECT was measured at baseline in 187 of 211 patients. The mean (s.d.) serum urate level (μmol/l) decreased from 501 (80) at baseline to 311 (48) at 12 months, and 322 (67) at 24 months. DECT scores at all locations decreased during both the first and the second year (P <0.001 for all comparisons vs baseline), both for patients achieving and not achieving the sUA treatment target.ConclusionsIn patients with gout, urate depositions in ankles and feet as measured by DECT decreased both in the first and the second year, when patients were treated using a treat-to-target ULT strategy.

Glenoid "Pear Restoration" with the Traditional Latarjet versus Congruent Arc Modification: CT Assessment of Coracoid Morphology for Preoperative Planning

Glenoid "Pear Restoration" with the Traditional Latarjet versus Congruent Arc Modification: CT Assessment of Coracoid Morphology for Preoperative Planning

Gout of feet and ankles in different disease durations: diagnostic value of single-source DECT and evaluation of urate deposition with a novel semi-quantitative DECT scoring system

ObjectivesTo investigate the diagnostic performance of single-source dual-energy computed tomography (DECT) based on gemstone spectral imaging technology (including Discovery CT750HD and Revolution CT) in patients with suspected feet/ankles gouty arthritis, and evaluate the urate deposition with a novel semi-quantitative DECT scoring system.MethodsA total of 196 patients were consecutively included. Feet and ankles were evaluated in all patients by single-source DECT scan. The 2015 EULAR/ACR criteria were used as the reference for the diagnosis of gout. The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of DECT for the diagnosis of gout in the early (≤1 year), middle (1–3 years), and late (> 3 years) disease durations were calculated. Besides, a novel semi-quantitative DECT scoring system was assessed for the measurement of urate deposition, and the correlation between the scores and the clinical and serological data were also evaluated. Moreover, the influences of artifacts on the diagnostic performance of DECT were also determined.ResultsThe sensitivity, specificity, and AUC of DECT in 196 patients were 38.10, 96.43%, and 0.673 in the early-stage group; 62.96, 100.00%, and 0.815 in the middle-stage group; and 77.55, 87.50%, and 0.825 in the late-stage group, respectively. The overall diagnostic accuracies in the AUC of DECT (Discovery CT750HD and Revolution CT) in the middle and late stages of gout were higher than that in the early stage of gout. Besides, the monosodium urate crystals were deposited on the first metatarsophalangeal joints and ankles/midfeet. Age, the presence of tophus, bone erosion, and disease duration considerably affected the total urate score. No statistical difference in the positive detection of nail artifact, skin artifact, vascular calcification, and noise artifact was found between the case and control groups.ConclusionDECT (Discovery CT750HD and Revolution CT) showed promising diagnostic accuracy for the detection of urate crystal deposition in gout but had limited diagnostic sensitivity for short-stage gout. Longer disease duration, the presence of tophus, and bone erosion were associated with the urate crystal score system. The artifacts do not remarkably affect the diagnostic performance of DECT in gout.

Erratum to Medical Physics article "Principles and applications of multienergy CT: Report of AAPM Task Group 291"

In AAPM Report 291, “Principles and applications of multienergy CT: Report of AAPM Task Group 291,”1 scientists from Canon Medical Systems Corporation, GE Healthcare Technologies, Philips Healthcare, and Siemens Healthcare GmbH participated as authors and contributed sections to describe, in general, the technology used in their company’s dual- or multi-energy CT systems. Specific scanner models were sometimes mentioned to provide examples of the overall approach. The general statements made about the approach may not, however, apply to the specific scanner model used as an example. The intermingling of the general and specific statements is regrettable, as it is ready source of potential confusion. Readers should view each section as a description of an overall dual- or multi-energy CT approach, even if a specific scanner model is mentioned as an example. Readers should refer to manufacturer specifications and the published literature to assess the specifications and performance of a specific CT system. A numerical error exists on page e895 in the second paragraph of the limitations section for kV switching. The statement “… so the system software currently prevents the use of gantry rotation times of less than approximately 500 ms, which may limit the quality of cardiac examinations,” implies that a minimum 500 ms rotation time applies to the scanner used as an example in the kV switching setting (GE Discovery CT750 HD). However, this value (500 msec) does not reflect the minimum rotation time on the GE Discovery CT750 HD. Rather, from the earliest publications on the use of this specific CT scanner model for dual-energy cardiac imaging, the minimum rotation time of 350 ms was used.2, 3 The second and third paragraphs in this same section on the limitations of kV switching reiterate the physics principles discussed on page e894, at the top of the second. Namely, as first demonstrated in 1979 by Kelcz et al., decreased spectral separation causes increased noise in decomposed material-specific images.4 In 2009, Primak et al. demonstrated that tube-specific filtration can increase spectral separation and decrease image noise in material decomposed images using a commercial dual-source CT system.5 While spectral separation is indeed an important determinant of the underlying noise properties of the acquired data, noise reduction methods can be applied such that the material decomposition calculations performed using kV switching (or other non-dual-source approaches) can also yield accurate quantification of iodine concentration.6

Reducing contrast medium dose with low photon energy images in renal dual-energy spectral CT angiography and adaptive statistical iterative reconstruction (ASIR)

To evaluate the value of using low energy (keV) images in renal dual-energy spectral CT angiography (CTA) and adaptive statistical iterative reconstruction (ASIR) to reduce contrast medium dose. 40 patients with renal CTA on a Discovery CT750HD were randomly divided into two groups: 20 cases (Group A) with 600 mgI kg-1 and 20 cases (Group B) with 300 mgI kg-1. The scan protocol for both groups was: dual-energy mode with mA selection for noise index of 10 HU, pitch 1.375:1, rotating speed 0.6 s/r. Images were reconstructed at 0.625 mm thickness with 40%ASIR, Group A used the conventional 70keV monochromatic images, and Group B used monochromatic images from 40 to 70 keV at 5 keV interval for analysis. The CT values and standard deviation (SD) values of the renal artery and erector spine in the plain and arterial phases were measured with the erector spine SD value representing image noise. The enhancement degree of the renal artery (ΔCT = CT(arterial) -CT(plain)), signal-to-noise ratio (SNR=CTrenal-artery/SDrenal-artery) and contrast-to-noise ratio (CNR=(CTrenal-artery-CTerector spine)/SDerector-spine) were calculated. The single factor analysis of variance was used to analyze the difference of ΔCT, SNR and CNR among image groups with p < 0.05 being statistically significant. The subjective image scores of the groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test. Contrast medium dose in the 300 mgI kg-1 group was reduced by 50% compared with the 600 mgI kg-1 group, while radiation dose was similar between the two groups. The subjective scores were 4.00 ± 0.65, 4.50 ± 0.60 and 3.70 ± 0.80 for images at 70 keV (600 mgI kg-1 group), 40 keV (300 mgI kg-1 group) and 45 keV (300 mgI kg-1 group), respectively with good consistency between the two reviewers (p > 0.05). The 40 keV images in the 300 mgI kg-1 group had similar ΔCT (469.77 ± 86.95 HU vs 398.54 ± 73.68 HU) and CNR (15.52 ± 3.32 vs 18.78 ± 6.71) values as the 70 keV images in the 600 mgI kg-1) group but higher SNR values (30.19 ± 4.41 vs 16.91 ± 11.12, p < 0,05). Contrast dose may be reduced by 50% while maintaining image quality by using lower energy images combined with ASIR in renal dual-energy CTA. Combined with ASIR and energy spectrum, can reduce the amount of contrast dose in renal CTA.

Comparison of radiation dose, contrast enhancement and image quality of prospective ECG-Gated CT coronary angiography: Single versus dual source CT

IntroductionThe updated National Institute of Clinical Excellence (NICE) guidelines of 2017 state that new generation cardiac CT scanners (Aquilion ONE, Brilliance iCT, Discovery CT750 HD and Somatom Definition Flash) are recommended as an option for first-line imaging of the coronary arteries in people with suspected stable coronary artery disease (with an estimated likelihood of coronary artery disease of 10–29%) in whom imaging with earlier generation CT scanners is difficult. New generation cardiac CT scanners are also recommended as an option for first-line evaluation of disease progression, to establish need for revascularisation in people with known coronary artery disease in whom imaging with earlier generation CT scanners is difficult. CT scanning might not be necessary in situations in which immediate revascularisation is being considered. The European Society of Cardiology 2019 clinical practice guidelines recommend non-invasive functional imaging for myocardial ischaemia or coronary CT angiography (CTA) as the initial test to diagnose CAD in symptomatic patients in whom obstructive CAD cannot be excluded by clinical assessment alone. Given increased computed tomography coronary angiogram (CTCA) utilisation, radiation dose, contrast enhancement and image quality of prospective ECG-gated CTCA between 256-slice single-source and 192x2-slice dual-source CT scanners were retrospectively evaluated. MethodsProspectively gated CTCA data from 63 patients on a 256-slice CT (group A) and 71 patients on a 192x2-slice dual source CT (group B) from January to December 2016 were retrospectively evaluated respectively. Scanner-reported dose length product values were used with a conversion factor (k = 0.014 mSv/mGy x cm) to estimate effective dose. Contrast enhancement was assessed with mean CT attenuation at selected regions of interest on axial coronary images. Image quality of the coronary arteries was assessed by a 4-point grading score (1 = non-diagnostic, 4 = excellent image quality). ResultsThe radiation doses in group B were significantly lower than group A (3.68 + 2.13 mSv versus 4.81 + 1.56 mSv, p < 0.001). There were no significant differences in contrast enhancement in the left coronary artery, proximal right coronary artery and left ventricular wall for both groups. Vessel image quality scores for group B were higher than group A (right coronary artery (RCA): 3.2 + 0.7 versus 2.4 + 0.7, p < 0.001; left anterior descending (LAD) artery: 3.0 + 0.8 vs 2.5 + 0.6, p < 0.001; left circumflex (LCx) artery: 3.3 + 0.7 vs 2.6 + 0.6, p < 0.001). Coronary artery contour scores for group B were significantly higher than group A (RCA: 3.2 + 0.8 versus 2.3 + 0.7, p < 0.001; LAD: 3.0 + 0.7 versus 2.4 + 0.6, p < 0.001; LCx: 3.3 + 0.6 versus 2.5 + 0.6, p < 0.001). ConclusionProspective ECG-gated CTCA performed on 192x2-slice CT results in better image quality and lower radiation dose than 256-slice CT. There were no significant differences in contrast enhancement in left main coronary artery (LMCA), proximal RCA and left ventricular wall in both groups. Implications for practiceIn institutions with both 256-slice and 192x2-slice CT scanners, we recommend that CTCAs be preferentially performed using the 192x2-slice CT scanner.

Evaluation of Spatial Resolution of Virtual Monochromatic Imaging In Vitro: Effect of Energy Level and Contrast.

Our aim was to evaluate effects of the energy level and contrast on the spatial resolution of virtual monochromatic imaging (VMI). With 2 types of computed tomographic (CT) scanners (Discovery CT750 HD and Revolution CT), we scanned an elliptical cylinder acrylic phantom with 20- or 40-fold dilutions of contrast medium and obtained VMI data sets at 40, 50, 60, and 70 keV. We evaluated the effects of energy levels and contrast on modulation transfer function (MTF) and the effect of energy levels on noise power spectra (NPS). With both CT scanners, MTF decreased significantly as the energy level decreased. The effect of the dilution of contrast media on MTF varied with CT scanners. With both scanners, NPS curves demonstrate uniform increase in NPS across the entire spatial frequency as the energy levels decreased. The energy level and contrast can affect the spatial resolution of VMIs.

Information technology for the analysis of CT perfusion in assessing the effectiveness of treatment for glioblastoma

Purpose of the study.To develop an information technology for calculating perfusion computed tomography parameters and to evaluate the effectiveness of using the proposed program in the differential diagnosis of continued glioblastoma growth and post-radiation necrosis.Materials and methods.We examined 53 patients who were treated at the Samara Clinical Oncological Dispensary. All patients underwent CT scan in perfusion mode. The results of using the program were compared with the data that were calculated on the workstation of the GE Discovery CT750 HD computed tomograph.Results.Significant differences were found in CBV and CBF perfusion indices in groups with continued growth and post-radiation necrosis, verified by biopsy. The parameters calculated using the developed program did not differ significantly from the results obtained on a standard workstation.Conclusion.The application of the developed computer program for the analysis of CT perfusion does not depend on the equipment manufacturer, works with standard DICOM data, which increases the availability of a valuable diagnostic method. The results obtained using the proposed information technology make it possible to differentiate the continued growth of glioblastoma from post-radiation necrosis.

Assessment of Hounsfield unit in the differential diagnosis of odontogenic cysts.

The purpose of this study was to evaluate the usefulness of Hounsfield unit (HU) assessment with multislice-CT in the differentiation of radicular cysts (RCs), dentigerous cysts (DCs) and odontogenic keratocysts (OKCs). In total, 307 odontogenic cysts (RCs, DCs and OKCs) were included in this study. Cysts with lesion diameter <10 mm, cysts with artefacts affecting measurement of HU values, cysts involving infection and recurrent cysts were regarded as exclusion criteria. Images were acquired in three different types of CT scanners: Aquilion ONE, Discovery CT750 HD and SOMATOM Definition Flash. Differences in HU values among scanners and among types of odontogenic cysts were assessed using one-way analysis of variance; multiple comparisons were performed post hoc, using the Tukey-Kramer honestly significant difference test. In total, 164 cysts were analysed in this study (64 RCs, 57 DCs and 43 OKCs). Regardless of the type of lesion, the Aquilion ONE scanner demonstrated a significant difference in HU value, compared with the Discovery CT750 HD scanner. Regardless of CT scanner model, HU values significantly differed between DCs and OKCs (p < 0.0001), as well as between OKCs and RCs (p < 0.0001). HU values were found to vary among CT scanners and should always be associated with other lesion imaging features while interpreting and elaboration diagnostic hypothesis. Notably, the results suggested that OKCs might be able to be differentiated from DCs and RCs by using HU values.

Cone-Beam CT Compared to Multi-Slice CT for the Diagnostic Analysis of Conductive Hearing Loss: A Feasibility Study

Multislice computed tomography (MSCT) is commonly used as a diagnostic tool for patients with a conductive hearing loss. Recent studies indicate that cone-beam computed tomography (CBCT) may be used as a low-radiation dose alternative for temporal bone imaging. This study compares image quality and radiation dose between CBCT and MSCT when assessing anatomical landmarks related to conductive hearing loss. Five human cadaver heads (10 ears) were imaged on the NewTom 5G CBCT and the Discovery CT750 HD MSCT. Visibility of 16 anatomical landmarks of the middle and inner ear was assessed by two observers on a 4-point Likert scale. Furthermore, effective radiation dose was compared, and contrast-to-noise ratio and spatial resolution were measured with a phantom head. Image quality of CBCT was assessed as superior to MSCT. Effective radiation dose of the high-resolution CBCT protocol was 30.5% of the clinical MSCT dose. High-resolution CBCT was reported as having a higher spatial resolution and superior contrast-to-noise perception in comparison with MSCT. High-resolution CBCT was evaluated as superior to MSCT in the assessment of structures related to conductive hearing loss. Furthermore, CBCT imaging resulted in a considerably lower effective radiation dose.

Dual-energy CT perfusion imaging for differentiating WHO subtypes of thymic epithelial tumors

To evaluate the role of conventional contrast-enhanced CT (CECT) imaging and dual-energy spectral CT (DECT) perfusion imaging in differentiating the WHO histological subtypes of thymic epithelial tumours (TETs). Eighty-eight patients with TETs who underwent DECT perfusion scans (n = 51) and conventional CT enhancement scans (n = 37) using a GE Discovery CT750 HD scanner were enrolled in this study. The mean maximal contrast-enhanced range (mean CEmax) and the perfusion and spectral parameters of the lesions were analysed. Among the six WHO subtypes (Type A, AB, B1, B2, and B3 thymoma and thymic carcinoma), the mean CEmax values and most of the perfusion and spectral parameter values of Type A and Type AB were significantly higher than those of the other subtypes (all P < 0.05), and there was no difference among Type B1, B2 and B3 (all P > 0.05). The mean CEmax value was not different between Type B (including Type B1, B2, and B3) and thymic carcinoma (P = 1.000). The PS, IC, NIC and λHU values in the optimal venous phase of thymic carcinoma were higher than those of Type B (all P < 0.05). The parameters of conventional CECT imaging and DECT perfusion imaging can help identify the subtype of TETs, especially those of DECT perfusion imaging in type B thymomas and thymic carcinomas.

Radiomics Analysis of Iodine-Based Material Decomposition Images With Dual-Energy Computed Tomography Imaging for Preoperatively Predicting Microsatellite Instability Status in Colorectal Cancer.

Purpose: The aim of this study was to investigate the value of radiomics analysis of iodine-based material decomposition (MD) images with dual-energy computed tomography (DECT) imaging for preoperatively predicting microsatellite instability (MSI) status in colorectal cancer (CRC).Methods: This study included 102 CRC patients proved by postoperative pathology, and their MSI status was confirmed by immunohistochemistry staining. All patients underwent preoperative DECT imaging scanned on either a Revolution CT or Discovery CT 750HD scanner, and the iodine-based MD images in the venous phase were reconstructed. The clinical, CT-reported, and radiomics features were obtained and analyzed. Data from the Revolution CT scanner were used to establish a radiomics model to predict MSI status (70% samples were randomly selected as the training set, and the remaining samples were used to validate); and data from the Discovery CT 750HD scanner were used to test the radiomics model. The stable radiomics features with both inter-user and intra-user stability were selected for the next analysis. The feature dimension reduction was performed by using Student's t-test or Mann–Whitney U-test, Spearman's rank correlation test, min–max standardization, one-hot encoding, and least absolute shrinkage and selection operator selection method. The multiparameter logistic regression model was established to predict MSI status. The model performances were evaluated: The discrimination performance was accessed by receiver operating characteristic (ROC) curve analysis; the calibration performance was tested by calibration curve accompanied by Hosmer–Lemeshow test; the clinical utility was assessed by decision curve analysis.Results: Nine top-ranked features were finally selected to construct the radiomics model. In the training set, the area under the ROC curve (AUC) was 0.961 (accuracy: 0.875; sensitivity: 1.000; specificity: 0.812); in the validation set, the AUC was 0.918 (accuracy: 0.875; sensitivity: 0.875; specificity: 0.857). In the testing set, the diagnostic performance was slightly lower with AUC of 0.875 (accuracy: 0.788; sensitivity: 0.909; specificity: 0.727). A nomogram based on clinical factors and radiomics score was generated via the proposed logistic regression model. Good calibration and clinical utility were observed using the calibration and decision curve analyses, respectively.Conclusion: Radiomics analysis of iodine-based MD images with DECT imaging holds great potential to predict MSI status in CRC patients.

Robust Beam Hardening Artifacts Reduction for Computed Tomography Using Spectrum Modeling

The aim of this paper is to develop a fast and accurate beam hardening correction method by modeling physical interactions between X-ray photons and materials for computed tomography (CT) imaging. The nonlinear attenuation process of the X-ray projection is modeled by reprojecting a template image with the estimated polychromatic spectrum. By adding the scaled difference of the monochromatic reprojection data and the polychromatic reprojection to the raw projection data, the raw projection data is mapped into the corresponding monochromatic projection data, which is to reconstruct the beam hardening artifacts corrected images. The algorithm can also be implemented in image-domain which takes the uncorrected image volume as input when there is an adequate model of the spectrum. In this case, the scaled difference is reconstructed to yield a set of artifacts images that can be added directly to the uncorrected images. Numerical simulations, experimental phantom data, and animal data which are acquired on a modern diagnostic CT scanner (Discovery CT750 HD, GE Healthcare, WI, USA), and a modern C-Arm CT scanner (Artis Zee, Siemens Healthcare, Forchheim, Germany), respectively, are used to evaluate the proposed method. The results show the proposed method significantly reduced both cupping and streak artifacts, and successfully recovered the Housfield units accuracy. Extensive studies suggest the proposed model-based method successfully corrects the beam hardening artifacts. This paper is practically useful and is promising to be applied to commercial products.

BLOOD MATRIX METALLOPROTEINASES LEVELS IN CYSTIC FIBROSIS CHILDREN (TEN YEARS OBSERVATION)

Introduction. Destructive fibrotic changes in lung tissue play a key role in the pathogenesis of cystic fibrosis (CF) in children. The development of pulmonary fibrosis may be caused by a violation of the pattern of matrix metalloproteinases (MMPs) and elevated production of profibrogenic growth factors (TGF-β1). Aim of the study. To compare the peculiarities of MMP patterns and transforming growth factor TGF-β1 with the data of the visualisation of airways features in cystic fibrosis (CF) children. Patients and Methods. The study included 80 inpatients aged of from 3 months to 18 years suffered from СF with the involvement of the lungs and digestive system observed for ten years. All patients were administered antibiotics (cefoperazone/sulbactam, ceftazidime, tienam, meropenem, amikacin) and inhalation (colisthmethate sodium, tobramycin) intravenously for a long time period. The reference group consisted of 16 children without pulmonary pathology. Blood serum concentrations of transforming growth factor-β1 (TGF-β1), matrix metalloproteinases (MMP-2, MMP-8, MMP-9) and tissue inhibitor of matrix metalloproteinases (TIMP-1) were determined by ELISA method. The morphological features of airways were evaluated by means of computer tomography (CT) with (GE Discovery CT750 HD). Results. In CF children patients blood serum MMP9 levels were significantly higher whereas TIMP-1 and MMP-2 appeared to be less than in children with intact airways. TGF-β1 levels in CF children were 9.8 times more than in cases from the reference group. CT data showed the pronounced changes in the airways structure as multiple bronchoectasias and pneumofibrosis. Conclusion. The revealed morphologic signs of the deterioration in airways’ structure in СF children patients can be related to the elevation of the rate of the fibrosis development due to the violation in the MMP and profibrogenic factors patterns and transforming growth factor TGF-β1.