Dual Energy Computerized Tomography Research Articles

Mono+ algorithm assessment of the diagnostic value of dual-energy CT for high-risk factors for colorectal cancer: a preliminary study.

Risk factors for colorectal cancer (CRC) affect the way patients are subsequently treated and their prognosis. Dual-energy computerized tomography (DECT) is an advanced imaging technique that enables the quantitative evaluation of lesions. This study aimed to evaluate the quality of DECT images based on the Mono+ algorithm in CRC, and based on this, to assess the value of DECT in the diagnosis of CRC risk factors. This prospective study was performed from 2021 to 2023. A dual-phase DECT protocol was established for consecutive patients with primary CRC. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), overall image quality, lesion delineation, and image noise of the dual-phase DECT images were assessed. Next, the optimal energy-level image was selected to analyze the iodine concentration (IC), normalized iodine concentration (NIC), effective atomic number, electron density, dual-energy index (DEI), and slope of the energy spectrum curve within the tumor for the high- and low-risk CRC groups. A multifactor binary logistic regression analysis was used to construct a differential diagnostic regression model for high- and low-risk CRC, receiver operating characteristic (ROC) curves were plotted, and the area under the curve (AUC) was calculated to assess the diagnostic value of the model. A total of 74 patients were enrolled in this study, of whom 41 had high-risk factors and 33 had low-risk factors. The SNR and CNR were best at 40 keV virtual monoenergetic imaging (VMI) based on the Mono+ algorithm (VMI+) (SNR 8.79±1.27, P<0.001; CNR 14.89±1.77, P=0.027). The overall image quality and lesion contours were best at 60 keV VMI+ and 40 keV VMI+, respectively (P=0.001). Among all the DECT parameters, the arterial phase (AP)-IC, NIC, DEI, energy spectrum curve, and venous phase-NIC differed significantly between the two groups. The AP-IC was the optimal DECT parameter for predicting high- and low-risk CRC with AUC, sensitivity, specificity, and cut-off values of 0.96, 97.06%, 87.80%, and 2.94, respectively, and the 95% confidence interval (CI) of the AUC was 0.88-0.99. Integrating the clinical factors and DECT parameters, the AUC, sensitivity, specificity, and predictive accuracy of the model were 0.99, 100.00%, 92.68%, and 94.67%, respectively, and the 95% CI of the AUC was 0.93-1.00. The DECT parameters based on 40 keV noise-optimized VMI+ reconstruction images depicted the CRC tumors best, and the clinical DECT model may have significant implications for the preoperative prediction of high-risk factors in CRC patients.

Quadruple-Rule-Out Computed Tomography Angiography (QRO-CT): A Novel Dual-Energy Computed Tomography Technique for the Diagnostic Work-Up of Acute Chest Pain.

Computerized tomography (CT) has been increasingly utilized in the differential diagnosis of acute chest pain. Combining the triple rule out CT angiography (TRO-CT) approach with dual-energy CT (DECT) can enhance the diagnostic capability by identifying myocardial perfusion deficiencies. This combination can yield a quadruple-rule-out computed tomography angiography (QRO-CT) technique. The aim of this study is to determine the efficacy of the QRO-CT. Intraluminal diseases and abnormalities in the main coronary arteries and branches were investigated. The myocardial dark spots on the color-coded iodine map were identified as perfusion deficiencies. Pulmonary arteries and aorta were also evaluated. The study population consisted of 211 patients. The sensitivity, specificity, and positive and negative predictive values of QRO-CT for pulmonary embolism were 93.5%, 100%, 100%, and 95.3%, respectively. For obstructive coronary artery disease, the values were 96.1%, 93.4%, 89.2%, and 97.7%, respectively. For myocarditis, the values were 69.2%, 100%, 100%, and 93.6%, respectively. the QRO-CT method may successfully evaluate myocardial perfusion deficits, hence expanding the differential diagnosis capabilities of the standard TRO-CT method for myocarditis. It can provide useful information on myocardial perfusion, which may influence the choice to perform invasive catheterization in cases of coronary artery obstruction.

Reduced-Dose Full-Body CT in Lymphoma Follow-up: A Pilot Study.

How to reduce the radiation dose received from full-body CT scans during the follow-up of lymphoma patients is a concern. The aim of the study was to investigate the image quality and radiation dose of reduced-dose full-body computerized tomography (CT) in lymphoma patients during the follow-up. 121 patients were included and divided into conventional CT group (group 1, 120-kVp, n = 61) or reduced-dose CT group (group 2, 100-kVp combined dual-energy CT (DECT), n = 60). 140-kVp polychromatic images and 70-keV monochromatic images were reconstructed from DECT. The abdominal virtual non-enhanced (VNE) images were reconstructed from monochromatic images. Two radiologists rated the overall image quality with a five-point scale and graded the depiction of lesions using a four-point scale. The objective image quality was evaluated using image noise, signal-to-noise ratio, and contrast-to-noise ratio. The radiation dose and image quality were compared between the groups. The comparable subjective image quality was observed between 70-keV and 120-kVp images in the neck, while 120-kVp images showed better objective image quality. 70-keV images showed better objective image quality in the chest. While the subjective image quality of abdominal VNE images was inferior to that of true non-enhanced images, the improved objective image quality was observed in VNE images. In the abdominal arterial phase, similar subjective image quality was observed between the groups. Abdominal 70-keV images in the arterial phase showed improved objective image quality. Similar image quality was obtained in the abdominal venous phase between the groups. The effective radiation dose in group 2 showed a significant reduction. The application of reduced-dose full-body CT can significantly reduce the radiation dose for lymphoma patients during the follow-up while maintaining or improving the image quality.

Towards subpercentage uncertainty proton stopping-power mapping via dual-energy CT: Direct experimental validation and uncertainty analysis of a statistical iterative image reconstruction method.

To assess the potential of a joint dual-energy computerized tomography (CT) reconstruction process (statistical image reconstruction method built on a basis vector model (JSIR-BVM)) implemented on a 16-slice commercial CT scanner to measure high spatial resolution stopping-power ratio (SPR) maps with uncertainties of less than 1%. JSIR-BVM was used to reconstruct images of effective electron density and mean excitation energy from dual-energy CT (DECT) sinograms for 10 high-purity samples of known density and atomic composition inserted into head and body phantoms. The measured DECT data consisted of 90 and 140 kVp axial sinograms serially acquired on a Philips Brilliance Big Bore CT scanner without beam-hardening corrections. The corresponding SPRs were subsequently measured directly via ion chamber measurements on a MEVION S250 superconducting synchrocyclotron and evaluated theoretically from the known sample compositions and densities. Deviations of JSIR-BVM SPR values from their theoretically calculated and directly measured ground-truth values were evaluated for our JSIR-BVM method and our implementation of the Hünemohr-Saito (H-S) DECT image-domain decomposition technique for SPR imaging. A thorough uncertainty analysis was then performed for five different scenarios (comparison of JSIR-BVM stopping-power ratio/stopping power (SPR/SP) to International Commission on Radiation Measurements and Units benchmarks; comparison of JSIR-BVM SPR to measured benchmarks; and uncertainties in JSIR-BVM SPR/SP maps for patients of unknown composition) per the Joint Committee for Guides in Metrology and the Guide to Expression of Uncertainty in Measurement, including the impact of uncertainties in measured photon spectra, sample composition and density, photon cross section and I-value models, and random measurement uncertainty. Estimated SPR uncertainty for three main tissue groups in patients of unknown composition and the weighted proportion of each tissue type for three proton treatment sites were then used to derive a composite range uncertainty for our method. Mean JSIR-BVM SPR estimates deviated by less than 1% from their theoretical and directly measured ground-truth values for most inserts and phantom geometries except for high-density Delrin and Teflon samples with SPR error relative to proton measurements of 1.1% and -1.0% (head phantom) and 1.1% and -1.1% (body phantom). The overall root-mean-square (RMS) deviations over all samples were 0.39% and 0.52% (head phantom) and 0.43% and 0.57% (body phantom) relative to theoretical and directly measured ground-truth SPRs, respectively. The corresponding RMS (maximum) errors for the image-domain decomposition method were 2.68% and 2.73% (4.68% and 4.99%) for the head phantom and 0.71% and 0.87% (1.37% and 1.66%) for the body phantom. Compared to H-S SPR maps, JSIR-BVM yielded 30% sharper and twofold sharper images for soft tissues and bone-like surrogates, respectively, while reducing noise by factors of 6 and 3, respectively. The uncertainty (coverage factor k=1) of the DECT-to-benchmark values comparison ranged from 0.5% to 1.5% and is dominated by scanning-beam photon-spectra uncertainties. An analysis of the SPR uncertainty for patients of unknown composition showed a JSIR-BVM uncertainty of 0.65%, 1.21%, and 0.77% for soft-, lung-, and bony-tissue groups which led to a composite range uncertainty of 0.6-0.9%. Observed JSIR-BVM SPR estimation errors were all less than 50% of the estimated k=1 total uncertainty of our benchmarking experiment, demonstrating that JSIR-BVM high spatial resolution, low-noise SPR mapping is feasible and is robust to variations in the geometry of the scanned object. In contrast, the much larger H-S SPR estimation errors are dominated by imaging noise and residual beam-hardening artifacts. While the uncertainties characteristic of our current JSIR-BVM implementation can be as large as 1.5%, achieving<1% total uncertainty is feasible by improving the accuracy of scanner-specific scatter-profile and photon-spectrum estimates. With its robustness to beam-hardening artifact, image noise, and variations in phantom size and geometry, JSIR-BVM has the potential to achieve high spatial-resolution SPR mapping with subpercentage accuracy and estimated uncertainty in the clinical setting.

P088 - Comparison of urinary stone composition using chemical analysis vs dual energy computerized tomography (DECT): A preliminary ex-vivo study

P088 - Comparison of urinary stone composition using chemical analysis vs dual energy computerized tomography (DECT): A preliminary ex-vivo study

The Use of Dual Energy Computerized Tomography to Detect Residual Viable Hepatocellular Carcinoma after Transarterial Chemoembolization

Objective: To determine the value of the dual energy computerized tomography (DECT) for detection of residual viable hepatocellular carcinoma (HCC) after transarterial chemoembolization (TACE). Methods: Single-source (ss) DECT of liver was performed in adult patients who were diagnosed as HCC and treated with TACE at Siriraj Hospital during October 1st, 2013- December 31st, 2014. The diagnostic 5-point performance score of conventional liver CT imaging set (CCTI) and iodinated material density imaging set (IMDI) obtained simultaneously by using DECT, were evaluated by two radiologists. The follow up imaging at 6 months was regarded as gold standard. The sensitivity and specificity were calculated by assigned score 4 or 5 lesions as positive for the presence of HCC, assigned score 1 or 2 lesions as negative for viable tumor and assigned score 3 lesions as uncertain diagnosis. McNemar’s test was used to compare the sensitivity and specificity between CCTI and IMDI. The reading time of both technique and radiation dose were recorded and the mean reading time were compared using a paired t-test. Results: Out of total 21 patients with 66 lesions, 81% were male and 19% were female with mean age 61.8 ± 10.2 years old. After monitoring for 6 months, 35 of the total 66 lesions were still viable HCCs and 31 lesions became non-viable HCCs. CCTI had excellent inter-observer agreement while IMDI had moderate agreement (K = 0.931 and 0.534, respectively). The sensitivity of CCTI and IMDI for detection of viable tumor were 88.6% and 100%, respectively (p-value cannot be computed). The specificity of CCTI and IMDI were 96.8% and 93.5%, respectively (p-value = 1.000). The mean reading time of two radiologists for CCTI was 151.2 ± 134.7 seconds and 123.2 ± 126.8 seconds for IMDI (p-value = 0.048). Total radiation dose of dynamic liver CT was 1194.22 ± 179.44 mGy cm. Conclusion: IMDI has higher sensitivity for detection of viable HCCs after TACE and consumes less reading time than CCTI.

Febuxostat in the treatment of gout patients with low serum uric acid level: 1-year finding of efficacy and safety study

To retrospectively analyze the efficacy and safety of febuxostat on gout patients with low serum uric acid level. A study was conducted in Nanjing First Hospital from October 2015 to September 2016. Thirty nine acute gouty arthritis patients from the emergency and outpatient department were included. Patients met the 2015 Gout Classification Criteria revised by American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) and had urate deposition around the joints detected by dual-energy computerized tomography (DECT). Patients whose serum uric acid (SUA) were between 5.0 and 7.0mg/dl (300-420μmol/l) received febuxostat treatment to maintain the SUA level between 3.0 and 5.0mg/dl for 1year. Efficacy and safety of febuxostat were observed during the process. Three of 39 subjects were excluded because of adverse events (AEs) after receiving an initial febuxostat treatment for 2months. Thirty six subjects were enrolled. The mean SUA level was reduced significantly from 6.51 ± 0.28mg/dl at baseline to 4.24 ± 0.38mg/dl and SUA of all subjects decreased by 34.8% compared with baseline. After 1-year treatment, the volume of tophus was reduced approximately 62.8%. Serum creatinine decreased stepwise in 8 gout patients with chronic kidney diseases from 162.5 ± 9.2μmol/l to 131.4 ± 11.0μmol/l. Two months after initiation of treatment, the number of gout flares began to markedly decrease and almost did not occur after 1year. After the 1-year treatment of febuxostat, the average SUA level declined significantly, and the renal function improved gradually. There was nearly complete abolition of gout flares by the end of the study. Tophi resolved markedly compared with baseline as assessed by DECT. Furthermore, only a few people experienced adverse events. Febuxostat has a notable effect for gout patients in the lower SUA level range.

P25 - Comparison of urinary stone composition using chemical analysis vs dual Energy Computerized Tomography (DECT) ex vivo: A preliminary study

P25 - Comparison of urinary stone composition using chemical analysis vs dual Energy Computerized Tomography (DECT) ex vivo: A preliminary study

Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors.

Background:Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors.Methods:Forty-five patients with solid tumors who had initial CT (Group B) and follow-up CT (Group A) after chemotherapy were enrolled. The initial diagnostic CT scan (Group B) was performed using the standard two-phase enhanced CT with 320 mgI/ml concentration contrast, and the follow-up scan (Group A) was performed using a single-phase enhanced CT at 45 s after the beginning of the 270 mgI/ml contrast injection using spectral mode. Forty percent ASiR was used for the images in Group B and monochromatic images with energy levels ≥60 keV in Group A. In addition, filtered back-projection (FBP) reconstruction was used for monochromatic images <60 keV in Group A. The total radiation dose, total iodine load, contrast injection speed, and maximum injection pressure were compared between the two groups. The 40 keV and 60 keV spectral CT images of Group A were compared with the images of Group B to evaluate overall image quality.Results:The total radiation dose, total iodine load, injection speed, and maximum injection pressure for Group A were decreased by 19%, 15%, 34.4%, and 18.3%, respectively. The optimal energy level in spectral CT for displaying the abdominal vessels was 40 keV. At this level, the CT values in the abdominal aorta and its three branches, the portal vein and its two branches, and the inferior vena cava were all greater than 340 hounsfield unit (HU). The abdominal organs of Groups A and B had similar degrees of absolute and relative enhancement (t = 0.36 and −1.716 for liver, −0.153 and −1.546 for pancreas, and 2.427 and 0.866 for renal cortex, all P > 0.05). Signal-to-noise ratio of the abdominal organs was significantly lower in Group A than in Group B (t = −8.11 for liver, −7.83 for pancreas, and −5.38 for renal cortex, all P < 0.05). However, the subjective scores for the 40 keV (FBP) and 60 keV (40% ASiR) spectral CT images determined by two radiologists were all >3, indicating clinically acceptable image quality.Conclusions:Single-phase, dual-energy spectral CT used for children with solid abdominal tumors can reduce contrast dose and radiation dose and can also maintain clinically acceptable image quality.

SU‐F‐T‐270: A Technique for Modeling a Diode Array Into the TPS for Lung SBRT Patient Specific QA

Purpose:To accurately match the treatment planning system (TPS) with the measurement environment, where quality assurance (QA) devices are used to collect data, for lung Stereotactic Body Radiation Therapy (SBRT) patient specific QA. Incorporation of heterogeneities is also studied.Methods:Dual energy computerized tomography (DECT) and single energy computerized tomography (SECT) were used to model phantoms incorporating a 2‐D diode array into the TPS. A water‐equivalent and a heterogeneous phantom (simulating the thoracic region of a patient) were studied. Monte Carlo and pencil beam planar dose distributions were compared to measured distributions. Composite and individual fields were analyzed for normally incident and planned gantry angle deliveries. γ‐ analysis was used with criteria 3% 3mm, 2% 2mm, and 1% 1mm.Results:The Monte Carlo calculations for the DECT resulted in improved agreements with the diode array for 46.4% of the fields at 3% 3mm, 85.7% at 2% 2mm, and 92.9% at 1% 1mm.For the SECT, the Monte Carlo calculations gave no agreement for the same γ‐analysis criteria. Pencil beam calculations resulted in lower agreements with the diode array in the TPS. The DECT showed improvements for 14.3% of the fields at 3% 3mm and 2% 2mm, and 28.6% at 1% 1mm.In SECT comparisons, 7.1% of the fields at 3% 3mm, 10.7% at 2% 2mm, and 17.9% at 1% 1mm showed improved agreements with the diode array.Conclusion:This study demonstrates that modeling the diode array in the TPS is viable using DECT with Monte Carlo for patient specific lung SBRT QA. As recommended by task groups (e.g. TG 65, TG 101, TG 244) of the American Association of Physicists in Medicine (AAPM), pencil beam algorithms should be avoided in the presence of heterogeneous materials, including a diode array.

1022 Dual Energy Computerized Tomography (DE-CT) for Predicting the Need for Surgery in Patients With Crohn's Disease and Obstructing Intestinal Lesions - Results of a Double Blind Prospective Study

1022 Dual Energy Computerized Tomography (DE-CT) for Predicting the Need for Surgery in Patients With Crohn's Disease and Obstructing Intestinal Lesions - Results of a Double Blind Prospective Study

879 Dual Energy Computerized Tomography (DE-CT) -A Novel Decision Making Tool in Predicting the Need for Surgery in Patients With Crohn's Disease and Obstructing Intestinal Lesions

879 Dual Energy Computerized Tomography (DE-CT) -A Novel Decision Making Tool in Predicting the Need for Surgery in Patients With Crohn's Disease and Obstructing Intestinal Lesions

AB1061 Comparing four imaging techniques of visualzing gouty tophi using one single patient

BackgroundGouty arthritis-causing uric acid is persistently in excess in the form of tophi. The ultimate therapeutic ideal should be to completely eliminate all tophi. So far, clinicians have relied on...

Use of X-Ray CT to Measure Pore Volume Compressibility of Shaybah Carbonates

SummaryThe Lower Cretaceous Shu'aiba formation (Shaybah field) in southeastern Saudi Arabia is a heterogeneous carbonate formation with various facies because of diagenetic alteration of the original rock fabric. Preliminary laboratory rock-mechanics studies indicated that the Shu'aiba carbonates are mechanically weak, with the majority of the rocks tested yielding very low strength values (less than 3,000 psi) when compared to samples from other carbonate reservoirs (Salamy and Finkbeiner 2002). On the basis of laboratory-derived rock-strength data from triaxial tests, the formation appears to behave in a plastic manner that strengthens the wellbore. To understand the stress behavior of the Shaybah rocks better, a set of pore volume compressibility tests was conducted in which the changes taking place within the samples were observed and quantified using an X-ray computerized-tomography (CT) scanner. A new technique involving dual-energy CT scanning was used to obtain the pore volume compressibility values, which were compared against the conventional triaxial-cell-generated data and published results by Harari et al. (1995) on cores taken from the same reservoir. Although the magnitude of the pore volume compressibility was the same between different setups, visual data showed some interesting behavior of the Shaybah cores including movement of grains in an irreversible manner even for a relatively low imposed effective stress of 2,000 psi. Some of the advantages of the new CT-based analysis technique include the generation of multiple pore volume compressibility curves from the same plug (a band of data, each at a different slice location), the "visualization" of the changes, the possibility of using either hydrostatic or triaxial cells to make the test more case-specific, and the possibility of measuring permeability under different stress conditions before, during, and after the test.

Estimation of the matrix attenuation in heterogeneous radioactive waste drums using dual-energy computed tomography

Gamma spectroscopy measurements of the activity of radionuclides in nuclear waste drums must be corrected for the attenuation due to the non-homogeneous waste matrix. The attenuation factors depend on the matrix local density and effective atomic number, and on the energy of the gamma rays emitted by the radionuclides. The requirements for the system presented in this paper are to estimate the attenuation in low-density (<0.4 g/cm 3), 120 l drums containing radionuclides emitting in the (59.5 keV, 1.4 MeV) energy range. A series of three-dimensional (3D) attenuation maps of the drum are computed using a dual-energy computerized tomography (DE-CT) system with an external, polychromatic X-ray source. The system successively records low-energy (mean energy about 62 keV) and high-energy (about 300 keV) projections using different tube voltages, anode current, and filtration. Each projection is acquired by 22 BGO scintillators – PM detectors in fan-beam geometry. The drum is rotated and elevated in a helical scan. A DE calibration transforms pairs of DE projections into pairs of “equivalent basis materials (BM)” projections. This non-linear transformation allows to correct for polychromaticity. After reconstruction, the two “equivalent BM” 3D maps are used, together with tabulated attenuation data of the BMs, in order to extrapolate the 3D attenuation map at any energy peak. Maps of the mass density and of the effective atomic number can also be computed. The total examination time is less than 5 min. Experimental images are shown.

Principles, History, and Status of Dual-Energy Computerized Tomographic Explosives Detection

Abstract A brief account is given of the principles of dual-energy computerized tomography (DECT) and of the potential which DECT has demonstrated for the automated detection of commercial and military explosives concealed in suitcases or packages. A description of a breadboard system configured for this purpose is provided and recent advances in the state of the art in CT are discussed in the light of their potential significance for explosives detection.