Extravasated contrast material in penetrating abdominopelvic trauma: dual-contrast dual-energy CT for improved diagnosis--preliminary results in an animal model.
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ABSTRACT:
SUBMITTER: Mongan J
PROVIDER: S-EPMC3750414 | biostudies-other | 2013 Sep
REPOSITORIES: biostudies-other
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Project description:To evaluate the feasibility of using a commercially available clinical dual-energy computed tomographic (CT) scanner to differentiate the in vivo enhancement due to two simultaneously administered contrast media with complementary x-ray attenuation ratios.Approval from the institutional animal care and use committee was obtained, and National Institutes of Health guidelines for the care and use of laboratory animals were observed. Dual-energy CT was performed in a set of iodine and tungsten solution phantoms and in a rabbit in which iodinated intravenous and bismuth subsalicylate oral contrast media were administered. In addition, a second rabbit was studied after intravenous administration of iodinated and tungsten cluster contrast media. Images were processed to produce virtual monochromatic images that simulated the appearance of conventional single-energy scans, as well as material decomposition images that separate the attenuation due to each contrast medium.Clear separation of each of the contrast media pairs was seen in the phantom and in both in vivo animal models. Separation of bowel lumen from vascular contrast medium allowed visualization of bowel wall enhancement that was obscured by intraluminal bowel contrast medium on conventional CT scans. Separation of two vascular contrast media in different vascular phases enabled acquisition of a perfectly coregistered CT angiogram and venous phase-enhanced CT scan simultaneously in a single examination.Commercially available clinical dual-energy CT scanners can help differentiate the enhancement of selected pairs of complementary contrast media in vivo.
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Project description:This paper addresses 123I and 125I dual isotope SPECT imaging, which can be challenging because of spectrum overlap in the low energy spectrums of these isotopes. We first quantify the contribution of low-energy photons from each isotope using GATE-based Monte Carlo simulations for the MOBY mouse phantom. We then describe and analyze a simple, but effective method that uses the ratio of detected low and high energy 123I activity to separate the mixed low energy 123I and 125I activities. Performance is compared with correction methods used in conventional tissue biodistribution techniques. The results indicate that the spectrum overlap effects can be significantly reduced, if not entirely eliminated, when attenuation and scatter is either absent or corrected for using standard methods. In particular, we show that relative activity levels of the two isotopes can be accurately estimated for a wide range of organs and provide quantitative validation that standard methods for spectrum overlap correction provide reasonable estimates for reasonable corrections in small-animal SPECT/CT imaging.
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Project description:PURPOSE:Evaluate Gadoxetate Disodium enhanced dual-energy CT for visualization of perihilar cholangiocarcinoma by exploiting the hepatobiliary uptake of Gadoxetate Disodium and viewing images at the k-edge of gadolinium on the spectrum of simulated monoenergetic energies available with Dual Energy CT. MATERIAL AND METHODS:In this prospective, IRB-approved study in patients with suspected cholangiocarcinoma, subjects who underwent a clinically indicated Gadoxetate Disodium liver MRI were immediately scanned without further IV contrast administration using rapid kVp-switching dual energy CT (rsDECT). Initial Gadoxetate Disodium dose was the FDA approved clinical dose, 0.025 mmol/kg; after additional IRB/FDA approval, 10 subjects were scanned with 0.05 mmol/kg. Both 50 keV and 70 keV simulated monoenergetic images as well as gadolinium(-water) material density images were viewed qualitatively and measured quantitatively for gadolinium uptake in the hepatic parenchyma and any focal lesions identified. RESULTS:Of 18 subjects (mean age 55 years, 10M, 8F, weight 84 kg), eight were scanned with 0.025 mmol/kg (Group 1) and 10 with 0.05 mmol/kg Gadoxetate Disodium (Group 2). Five patients had cholangiocarcinoma (all in Group 1). On synthetic monoenergetic images using standard and double Gadoxetate Disodium dose, the liver parenchyma did not appear enhanced qualitatively. Comparison of mean hepatic parenchymal HU at 50 and 70 keV showed a measurable increase in attenuation at the lower viewing energy, which corresponded to the k-edge of gadolinium. No statistically significant difference was observed on quantitative gadolinium measurement of hepatic parenchyma for single versus double Gadoxetate Disodium dose using rsDECT gadolinium material density images. Of the five cholangiocarcinomas, the tumor to nontumoral hepatic tissue HU differences were 51.1 (32.2) (mean and std dev) and 49.0(26.5) at 50 and 70 keV, respectively. CONCLUSION:In this small pilot population, evaluation of potential hilar/perihilar cholangiocarcinoma using dual energy CT at both the single FDA-approved dose and double dose of gadolinium demonstrated observed differences in attenuation between the hepatic parenchyma and lesions. However, small sample size and heterogeneity of lesions warrants further investigation.
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Project description:Dual-energy computed tomography (DECT) imaging plays an important role in advanced imaging applications due to its material decomposition capability. Image-domain decomposition operates directly on CT images using linear matrix inversion, but the decomposed material images can be severely degraded by noise and artifacts. This paper proposes a new method dubbed DECT-MULTRA for image-domain DECT material decomposition that combines conventional penalized weighted-least squares (PWLS) estimation with regularization based on a mixed union of learned transforms (MULTRA) model. Our proposed approach pre-learns a union of common-material sparsifying transforms from patches extracted from all the basis materials, and a union of cross-material sparsifying transforms from multi-material patches. The common-material transforms capture the common properties among different material images, while the cross-material transforms capture the cross-dependencies. The proposed PWLS formulation is optimized efficiently by alternating between an image update step and a sparse coding and clustering step, with both of these steps having closed-form solutions. The effectiveness of our method is validated with both XCAT phantom and clinical head data. The results demonstrate that our proposed method provides superior material image quality and decomposition accuracy compared to other competing methods.
| S-EPMC7263375 | biostudies-literature
Project description:PurposeThe dual-energy CT (DECT) LiverVNC application class in the Siemens Syngo.via software has been used to perform non-iodine material decompositions. However, the LiverVNC application is designed with an optional size-specific calibration based on iodine measurements. This work investigates the effects of this iodine-based size-specific calibration on non-iodine material decomposition and benchmarks alternative methods for size-specific calibrations.MethodsCalcium quantification was performed with split-filter and sequential-scanning DECT techniques on the Siemens SOMATOM Definition Edge CT scanner. Images were acquired of the Gammex MECT abdomen and head phantom containing calcium inserts with concentrations ranging from 50-300 mgCa/ml. Several workflows were explored investigating the effects of size-specific dual-energy ratios (DERs) and the beam hardening correction (BHC) function in the LiverVNC application. Effects of image noise were also investigated by varying CTDIvol and using iterative reconstruction (ADMIRE).ResultsWith the default BHC activated, Syngo.via underestimated the calcium concentrations in the abdomen for sequential-scanning acquisitions, leaving residual calcium in the virtual non-contrast images and underestimating calcium in the enhancement images for all DERs. Activation of the BHC with split-filter images resulted in a calcium over- or underestimation depending on the DER. With the BHC inactivated, the use of a single DER led to an under- or overestimate of calcium concentration depending on phantom size and DECT modality. Optimal results were found with BHC inactivated using size-specific DERs. CTDIvol levels and ADMIRE had no significant effect on results.ConclusionWhen performing non-iodine material decomposition in the LiverVNC application class, it is important to understand the implications of the BHC function and to account for patient size appropriately. The BHC in the LiverVNC application is specific to iodine and leads to inaccurate quantification of other materials. The inaccuracies can be overcome by deactivating the BHC function and using size-specific DERs, which provided the most accurate calcium quantification.
| S-EPMC8664138 | biostudies-literature
Project description:Background and purposeIdentification of ICH, particularly after ischemic stroke therapy, is important for guiding subsequent antithrombotic management and is often confounded by contrast staining or extravasations within intracerebral or extra-axial compartments. This study evaluates the accuracy of DECT in distinguishing ICH from iodinated contrast in patients who received contrast via IA or IV delivery.Materials and methodsForty patients who had received IA or IV contrast were evaluated using a DECT scanner at 80kV and 140kV to distinguish hyperdensities secondary to contrast staining or extravasation from those representing ICH. A 3-material decomposition algorithm was used to obtain virtual noncontrast images and iodine overlay images. Sensitivity, specificity, and accuracy of DECT in prospectively distinguishing intracranial contrast from hemorrhage within parenchymal, subarachnoid, extra-axial, intraventricular, and intra-arterial compartments were computed using routine clinical follow-up imaging as the standard of reference.ResultsA total of 148 foci of intracranial hyperattenuation were identified. Of these, 142 were correctly classified for the presence of hemorrhage by DECT. The sensitivity, specificity, and accuracy for identifying hemorrhage, depending on the compartment being considered, were 100%, 84.4%-100%, and 87.2%-100%, respectively. The only instances where DECT failed to correctly identify the source of hyperattenuation was in the presence of diffuse parenchymal calcification (n = 5) and a metallic streak artifact (n = 1).ConclusionAfter IA and/or IV contrast administration, DECT can accurately differentiate all types of ICH from iodinated contrast without employing any additional radiation.
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Project description:ObjectiveOne of the main drawbacks associated with Dual Energy Computed Tomography Angiography (DECTA) is the risk of developing contrast medium-induced nephropathy (CIN). The aim of the present study was firstly, to design an optimal CT imaging protocol by determining the feasibility of using a reduced contrast medium volume in peripheral arterial DECTA, and secondly, to compare the results with those obtained from using routine contrast medium volume.MethodsThirty four patients underwent DECTA for the diagnosis of peripheral arterial disease. They were randomly divided into two groups: Group 1 (routine contrast volume group) with n = 17, injection rate 4-5 ml/s, and 1.5 ml/kg of contrast medium, and Group 2 ((low contrast volume group), with n = 17, injection rate 4-5ml/s, and contrast medium volume 0.75 ml/kg. A fast kilovoltage-switching 64-slice CT scanner in the dual-energy mode was employed for the study. A total of 6 datasets of monochromatic images at 50, 55, 60, 65, 70 and 75 keV levels were reconstructed with adaptive statistical iterative reconstruction (ASIR) at 50%. A 4-point scale was the tool for qualitative analysis of results. The two groups were compared and assessed quantitatively for image quality on the basis of signal-to-noise ratio (SNR) and contrast-to-noise-ratio (CNR). Radiation and contrast medium doses were also compared.ResultsThe overall mean CT attenuation and mean noise for all lower extremity body parts was significantly lower for the low volume contrast group (p<0.001), and varied significantly between groups (p = 0.001), body parts (p<0.001) and keVs (p<0.001). The interaction between group body parts was significant with CT attenuation and CNR (p = 0.002 and 0.003 respectively), and marginally significant with SNR (p = 0.047), with minimal changes noticed between the two groups. Group 2 (low contrast volume group) displayed the lowest image noise between 65 and 70 keV, recorded the highest SNR and CNR at 65 keV, and produced significantly lower results with respect to contrast medium volume and duration of contrast injection (p<0.001). The effect of radiation dose was not statistically significant between the two groups.ConclusionsDECTA images created at 65 keV and 50% ASIR with low contrast medium volume protocol, yielded results that were comparable to routine contrast medium volume, with acceptable diagnostic images produced during the evaluation of peripheral arteries.
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Project description:Chemical staining of soft-tissues can be used as a strategy to increase their low inherent contrast in X-ray absorption micro-computed tomography (micro-CT), allowing to obtain fast three-dimensional structural information of animal organs. Though some staining agents are commonly used in this context, little is known about the staining agents' ability to stain specific types of tissues; the times necessary to provide a sufficient contrast; and the effect of staining solution in distorting the tissue. Here we contribute to studies of animal organs (mouse heart and lungs) using staining combined with dual-energy micro-CT (DECT). DECT was used in order to obtain an additional quantitative measure for the amount of staining agents within the sample in 3D maps. Our results show that the two staining solutions used in this work diffuse differently in the tissues studied, the staining times of some tens of minutes already produce high-quality micro-CT images and, at the concentrations applied in this work, the staining solutions tested do not cause relevant tissue distortions. While one staining solution provides images of the general morphology of the organs, the other reveals organs' features in the order of a hundred micrometers.
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Project description:PurposeTo evaluate the influence of different scan parameters for single-energy CT and dual-energy CT, as well as the impact of different material used in a TKA prosthesis on image quality and the extent of metal artifacts.MethodsEight pairs of TKA prostheses from different vendors were examined in a phantom set-up. Each pair consisted of a conventional CoCr prosthesis and the corresponding anti-allergic prosthesis (full titanium, ceramic, or ceramic-coated) from the same vendor. Nine different (seven dual-energy CT and two single-energy CT) scan protocols with different characteristics were used to determine the most suitable CT protocol for TKA imaging. Quantitative image analysis included assessment of blooming artifacts (metal implants appear thicker on CT than they are, given as virtual growth in mm in this paper) and streak artifacts (thick dark lines around metal). Qualitative image analysis was used to investigate the bone-prosthesis interface.ResultsThe full titanium prosthesis and full ceramic knee showed significantly fewer blooming artifacts compared to the standard CoCr prosthesis (mean virtual growth 0.6-2.2 mm compared to 2.9-4.6 mm, p?<?0.001). Dual-energy CT protocols showed less blooming (range 3.3-3.8 mm) compared to single-energy protocols (4.6-5.5 mm). The full titanium and full ceramic prostheses showed significantly fewer streak artifacts (mean standard deviation 77-86 Hounsfield unit (HU)) compared to the standard CoCr prosthesis (277-334 HU, p?<?0.001). All dual-energy CT protocols had fewer metal streak artifacts (215-296 HU compared to single-energy CT protocols (392-497 HU)). Full titanium and ceramic prostheses were ranked superior with regard to the image quality at the bone/prosthesis interface compared to a standard CoCr prosthesis, and all dual-energy CT protocols were ranked better than single-energy protocols.ConclusionsDual-energy CT and ceramic or titanium prostheses reduce CT artifacts and provide superior image quality of total knee arthroplasty at the bone/prosthesis interface. These findings support the use of dual-energy CT as a solid imaging base for clinical decision-making and the use of full-titanium or ceramic prostheses to allow for better CT visualization of the bone-prosthesis interface.
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Project description:Dual-energy computed tomography has been proposed for enhancing the evaluation of coronary artery disease in many fronts. However, the clinical translation of such applications has followed a slower pace of clinical translation. This paper will review the evidence supporting the use of dual-energy computed tomography in coronary artery disease (CAD) and provide some practical illustrations, while underscoring the challenges and gaps in knowledge that have contributed to this phenomenon.
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