Contrast Enhancement Material Research Articles

Preparation and Biocompatibility Study of Contrast-Enhanced Hernia Mesh Material.

Meshes play a crucial role in hernia repair. However, the displacement of mesh inevitably leads to various associated complications. This process is difficult to be traced by conventional imaging means. The purpose of this study is to create a contrast-enhanced material with high-density property that can be detected by computed tomography (CT). The contrast-enhanced monofilament was manufactured from barium sulfate nanoparticles and medical polypropylene (PP/Ba). To characterize the composite, stress tensile tests and scanning electron microscopy (SEM) was performed. Toxicity and biocompatibility of PP/Ba materials was verified by in vitro cellular assays. Meanwhile, the inflammatory response was tested by protein adsorption assay. In addition, an animal model was established to demonstrate the long-term radiographic effect of the composite material in vivo. Subsequent pathological tests confirmed its in vivo compatibility. The SEM revealed that the main component of the monofilament is carbon. In vitro cell experiments demonstrated that novel material does not affect cell activity and proliferation. Protein adsorption assays indicated that the contrast-enhanced material does not cause additional inflammatory responses. In addition, in vivo experiments illustrated that PP/Ba mesh can be detected by CT and has good in vivo compatibility. These results highlight the excellent biocompatibility of the contrast-enhanced material, which is suitable for human abdominal wall tissue engineering.

On the conditioning of basis materials and its impact on multimaterial decomposition-based spectral imaging in photon-counting CT.

Material-specific imaging and virtual monochromatic imaging/analysis are the two forms of spectral imaging in CT implemented via either energy-integration or photon-counting data acquisition. Aimed at further understanding the fundamentals and providing guidelines on its design and implementation, we quantitatively investigate the conditioning (sufficiency in dimensionality, well-posedness in basis functions, and matching of K-edge materials) of basis materials and its impact on the performance of spectral imaging in photon-counting CT. Initially, singular value decomposition (SVD) is employed to investigate the dimensionality of material space for multimaterial decomposition-based spectral imaging in photon-counting CT over the energy range [18 150] keV. Then, the SVD is extended to study the well-posedness of basis functions, its relationship with the dimensionality of materials to be imaged, and its impact on imaging performance. A number of phantoms are designed to mimic the soft and bony tissues in the head and contrast enhancement materials (iodine and gadolinium). Simulation studies, in which the geometry of photon-counting CT is similar to a clinical CT, are carried out to evaluate and verify the proposed approach of conditioning analysis and the relationship between the conditioning of basis materials and the performance of spectral imaging in photon-counting CT. The preliminary data show that the dimensionality of biological tissues, including both soft and bony tissues, is effectively equal to two. The dimensionality increments with inclusion of K-edge materials into the materials to be imaged. The well-posedness of basis functions depends on the correlation between the functions and impacts the noise in material decomposition substantially, but affects the noise in virtual monochromatic imaging/analysis moderately. If a K-edge material is in the materials to be imaged, the same K-edge material has to be one of the basis materials, but its concentration does not affect the accuracy of material decomposition significantly. Moreover, inclusion of K-edge material into the basis material makes the tuning of correlation among the basis functions feasible and thus improves the performance of spectral imaging in photon-counting CT. The extension of SVD for systematic analysis of multimaterial decomposition-based spectral imaging in photon-counting CT is of innovation and significance. In addition to providing more information on the fundamentals, the approach used in this study and the data obtained so far may provide guidelines on the implementation of spectral imaging in either photon-counting or energy-integration CT, as well as other x-ray-related imaging modalities such as radiography and tomosynthesis.

Comparison of image quality between synthetic and patients' electrocardiogram-gated 320-row pediatric cardiac computed tomography

Pediatric cardiac computed tomography (CT) can be acquired without electrode placement by using synthetic electrocardiogram (ECG). To determine whether the depiction of gross cardiac structures and coronary arteries in 320-row pediatric CT is not inferior when CT is gated with synthetic ECG at 150 beats per minute (bpm), compared to the patients' own ECG. Sixty 320-row CT examinations performed in children younger than 3 years old with congenital cardiac anomaly were enrolled in this retrospective study. Thirty examinations were scanned using the children's own ECG for gating and 30 examinations were scanned using synthetic ECG at 150 bpm. The image quality was compared between the two gating modes using a 3-point scale to delineate the following anatomical structures: atrial septum, ventricular septum, right atrium, right ventricle, left atrium, left ventricle, main pulmonary artery, ascending aorta, aortic arch including the patent ductus arteriosus, descending aorta, right coronary artery and left main trunk. Beam-hardening artifacts from contrast enhancement material were evaluated using a 3-point scale, and the overall image quality was evaluated using a 5-point scale. Synthetic ECG was not inferior to the patients' ECG in depicting each structure, beam-hardening artifact and overall image quality. Average indices were clinically acceptable imaging quality, except for subjective image quality of mid and distal coronary arteries. Pediatric cardiac CT in patients younger than 3 years old can be acquired using synthetic ECG gating, with image quality not inferior to the patients' ECG.

Applying Machine Learning Methods Toward Classification Based on Small Datasets: Application to Shoulder Labral Tears

Abstract Machine learning is a powerful tool that can be applied to pattern search and mathematical optimization for making predictions on new data with unknown labels. In the field of medical imaging, one challenge with applying machine learning techniques is the limited size and relative expense of obtaining labeled data. For example, in glenoid labral tears, current imaging diagnosis is best achieved by imaging through magnetic resonance (MR) arthrography, a method of injecting contrast-enhancing material into the joint that can potentially cause discomfort to the patient, and adds expense compared to a standard magnetic resonance image (MRI). This work proposes limiting the use of MR arthrography through a medical diagnostic approach, based on convolutional neural networks (CNNs) and transfer learning from a separate medical imaging dataset to improve the efficiency and effectiveness. The results indicate an effective method applied to a small dataset of unenhanced shoulder MRI in order to diagnose labral tear severity while potentially significantly reducing cost and reducing unnecessary invasive imaging techniques. The proposed method ultimately can reduce physician workload while ensuring that the least number of patients as possible need to be subjected to an additional invasive contrast-enhanced imaging procedure.

The Surface-Volume Coefficient of the Superficial and Deep Facial Fat Compartments: A Cadaveric Three-Dimensional Volumetric Analysis.

Soft-tissue filler injections for the treatment of facial aging can result in different skin surface effects depending on the targeted facial fat compartment and fascial plane. This work investigates the tissue response of defined amounts of soft-tissue filler material injected into superficial and deep facial fat compartments by means of the calculation of the surface-volume coefficient. Four fresh frozen cephalic specimens obtained from human donors (three female and one male; mean age, 74.96 ± 22.6 years; mean body mass index, 21.82 ± 6.3 kg/m) were studied. The superficial and deep lateral forehead compartments, deep temporal fat pad, sub-orbicularis oculi fat compartment, and deep medial cheek fat compartment were injected with aliquots of 0.1 cc of contrast-enhanced material and scanned using three-dimensional surface imaging, resulting in a total of 226 injection and scanning procedures. The sub-orbicularis oculi fat compartment revealed the highest correlation coefficient (rp = 0.992; p < 0.001) and the highest surface-volume coefficient (0.94). The compartment with the lowest tissue response was the deep medial cheek fat compartment (rp = 0.745; p < 0.001; surface-volume coefficient = 0.29), followed by the deep lateral forehead compartment (rp = 0.814; p < 0.001; surface-volume coefficient = 0.68), superficial lateral forehead compartment (rp = 0.824; p < 0.001; surface-volume coefficient = 0.74), and deep temporal fat pad (rp = 0.947; p < 0.001; overall surface-volume coefficient = 0.64). These results, confirmatory in their nature to current injection strategies, provide evidence for the validity and reliability of the surface-volume coefficient. Injection procedures should be targeted in terms of facial fat compartments and fascial planes for a desired aesthetic outcome, as each fat compartment and fascial plane has unique tissue responses to injected soft-tissue fillers.

Evaluating the Association Between the Extent of Resection and Survival in Gliosarcoma.

Introduction: Gliosarcoma (GS) is a rare, malignant mixed tumor of the central nervous system with a median survival of approximately 13 months across multiple studies. Although the value of the extent of resection (EOR) has been confirmed as a prognostic survival factor in glioblastoma, no such association has been defined for GS. The goal of this study was to establish an association between EOR and survival and to determine if a threshold of resection exists for which a survival benefit is conferred in GS.Methods: The authors identified 11 patients with histologically confirmed GS between January 2005 and January 2015, treated at the Hospital of the University of Pennsylvania. Clinical, radiographic, and outcome data were retrospectively reviewed. Volumetric analysis was completed using semi-automated segmentation to measure the change in contrast-enhancing material based on preoperative T1-contrast (T1c) and postoperative T1 & T1c magnetic resonance imaging (MRI) scans. A log-rank test was completed to confirm an association between EOR and survival, and a series of Kaplan-Meier curves were constructed to determine an EOR threshold. Univariate Cox proportional hazards model (CPHM) followed by multivariate CPHM was also completed to evaluate associations between the prognostic clinical and immunohistochemistry variables under consideration.Results: Extent of resection categories were defined as gross total resection (GTR >95%), subtotal resection (STR 90%-95%), and partial resection (PR <90%). The median overall survival for the groups were as follows: GTR-17.3 months (n=4), STR-12.6 months (n=5), PR-4.3 months (n=2). A statistically significant association (p=05 level) was found between survival and the PR group with the GTR group as reference. Multivariate CPHM confirmed a statistically significant association between increased survival and age, preoperative Karnofsky Performance Status (KPS) scores, postoperative KPS scores, and KI-67 index. Serial Kaplan-Meier curves suggest a survival benefit with an EOR threshold of 94%.Conclusion: This study agrees with previous correlations in glioblastoma EOR and prolonged survival. For patients undergoing surgical resection for GS, maximal surgical removal, when safely possible, should be attempted as it appears to translate to longer survival times.

Pediatric 320-row cardiac computed tomography using electrocardiogram-gated model-based full iterative reconstruction

BackgroundFull iterative reconstruction algorithm is available, but its diagnostic quality in pediatric cardiac CT is unknown.ObjectiveTo compare the imaging quality of two algorithms, full and hybrid iterative reconstruction, in pediatric cardiac CT.Materials and methodsWe included 49 children with congenital cardiac anomalies who underwent cardiac CT. We compared quality of images reconstructed using the two algorithms (full and hybrid iterative reconstruction) based on a 3-point scale for the delineation of the following anatomical structures: atrial septum, ventricular septum, right atrium, right ventricle, left atrium, left ventricle, main pulmonary artery, ascending aorta, aortic arch including the patent ductus arteriosus, descending aorta, right coronary artery and left main trunk. We evaluated beam-hardening artifacts from contrast-enhancement material using a 3-point scale, and we evaluated the overall image quality using a 5-point scale. We also compared image noise, signal-to-noise ratio and contrast-to-noise ratio between the algorithms.ResultsThe overall image quality was significantly higher with full iterative reconstruction than with hybrid iterative reconstruction (3.67±0.79 vs. 3.31±0.89, P=0.0072). The evaluation scores for most of the gross structures were higher with full iterative reconstruction than with hybrid iterative reconstruction. There was no significant difference between full and hybrid iterative reconstruction for the presence of beam-hardening artifacts. Image noise was significantly lower in full iterative reconstruction, while signal-to-noise ratio and contrast-to-noise ratio were significantly higher in full iterative reconstruction.ConclusionThe diagnostic quality was superior in images with cardiac CT reconstructed with electrocardiogram-gated full iterative reconstruction.

Role of Magnetic Resonance Cholangiopancreatography in Biliary Disorders

Magnetic resonance cholangiopancreatography or MRCP is a technique that uses a powerful magnetic field to evaluate the disorders of liver, gallbladder, bile ducts, pancreas and pancreatic duct. This technique was introduced in 1991 & has evolved rapidly over last two decades as it is non-invasive, does not require anaesthesia or contrast enhancing material and is less operator dependent. Although at present endoscopic cholangiopancreatography (ERCP) is the gold standard in evaluating the pancreaticobiliary disorders but is invasive, operator dependent and results in complications such as cholangitis, pancreatitis, haemorrhage and perforation of duodenum which have limited its routine use and has made MRCP as a routine investigation in evaluating biliary tree disorders. Furthermore MRCP is superior to ERCP in diagnosing the biliary disorders in the settings where biliary anatomy is distorted due to previous pancreatic biliary surgeries. MRCP is a technique that uses heavily weighted T2 sequences which highly enhances static or slowly flowing bile against non-enhancing surrounding soft tissue which makes the evaluation of biliary tree more accurate and easy.

Adrenal Incidentaloma triage with single-source (fast-kilovoltage switch) dual-energy CT.

The purpose of this article is to evaluate single-source dual-energy CT (DECT) for distinguishing benign and indeterminate adrenal nodules, with attention to the effects of phase of IV contrast enhancement. A retrospective review revealed 273 contrast-enhanced abdominal DECT examinations from November 2009 through March 2012. Fifty adrenal nodules 0.8 cm or larger were identified in 41 patients (22 women and 19 men; average age, 66 years; age range, 36-88 years). CT postprocessing and measurements were independently performed by two radiologists (readers 1 and 2) for each nodule, as follows: attenuation (in Hounsfield units) on true unenhanced images; contrast-enhanced attenuation (in Hounsfield units) on monochromatic spectral images at 40, 75, and 140 keV; and contrast-enhanced material density (in milligrams per milliliter) on virtual unenhanced images. Nodules were classified as benign (< 10 HU) and indeterminate (≥ 10 HU) according to true unenhanced images. Interreader agreement regarding benign and indeterminate nodules was high (κ = 0.92; 95% CI, 0.8-1.0). At 140 keV, the attenuation of benign nodules was significantly lower (reader 1, 7.0 ± 12.5 HU; reader 2, 7.8 ± 9.2 HU) than that of indeterminate nodules (reader 1, 15.7 ± 20.5 HU [p = 0.004]; reader 2, 17.5 ± 13.4 HU [p < 0.0001]). On virtual unenhanced images, benign nodules had significantly lower material density (reader 1, 992.4 ± 9.9 mg/mL; reader 2, 992.7 ± 9.6 mg/mL) than did indeterminate nodules (reader 1, 1001.1 ± 20.5 mg/mL [p = 0.038]; reader 2, 1007.6 ± 13.4 mg/mL [p < 0.0001]). DECT tools can mathematically subtract iodine or minimize its effects in high-energy reconstructions, approximating unenhanced imaging and potentially reducing the need for additional studies to triage adrenal nodules detected on contrast-enhanced DECT examinations.

Presumptive meningoencephalitis secondary to extension of otitis media/interna caused by Streptococcus equi subspecies zooepidemicus in a cat

A 5-year-old castrated male domestic longhair cat was presented with neurological signs consistent with a central vestibular lesion and left Horner’s syndrome. Computed tomography images revealed hyperattenuating, moderately contrast-enhancing material within the left tympanic bulla, most consistent with left otitis media/interna. Marked neutrophilic pleocytosis was identified on cerebrospinal fluid analysis. Streptococcus equi subspecies zooepidemicus (SEZ) was isolated from the cerebrospinal fluid. Intracranial extension of otitis media/interna is relatively infrequent in small animals. There are no reports of otitis media/interna caused by SEZ in dogs or cats. This is the first report of otitis media/interna and presumptive secondary meningoencephalitis caused by SEZ in a cat.

Hepatic angiomyolipoma: Dynamic computed tomography features and clinical correlation

To study the dynamic computed tomography (CT) features of hepatic angiomyolipoma (AML) in patients with or without tuberous sclerosis complex (TSC). The clinical information, CT findings and histopathological results of hepatic AML were analyzed retrospectively in 10 patients. Hepatic AML was prone to occur in female patients (7/10), and most of the patients (8/10) had no specific symptoms. All tumors presented as well-defined, unenveloped nodules in the liver. Six patients with sporadic hepatic AML had a solitary hepatic nodule with a definite fat component. Non-fat components of the hepatic lesions were enhanced earlier and persistently. Prominent central vessels were noted in the portal venous phase in three patients. In four patients with hepatic AML and TSC, most of the nodules were within the peripheral liver. Seven fat-deficient nodules were found with earlier contrast enhancement and rapid contrast material washout in two patients. Lymphangioleiomyomatosis was found in one patient. Imaging features of hepatic AML are characteristic. Correct diagnosis preoperatively can be made in combination with clinical features.

High aspect ratio air core solenoid inductors using an improved UV-LIGA process with contrast enhancement material

In this paper, we investigate the application of a contrast enhancement material (CEM388SS®, Shin-Etsu MicroSi, Inc., AZ, USA) on thick SU-8 negative photoresist (Microchem Corp., MA, USA) and its ...

High aspect ratio air core solenoid inductors using an improved UV-LIGA process with contrast enhancement material

In this paper, we investigate the application of a contrast enhancement material (CEM388SS®, Shin-Etsu MicroSi, Inc., AZ, USA) on thick SU-8 negative photoresist (Microchem Corp., MA, USA) and its use in the construction of a high aspect ratio on-chip solenoid inductor. Various SU8 test microstructures (with aspect ratio of 10:1 and 20:1) were first constructed by utilizing this improved UV-LIGA process to demonstrate the clear difference before and after the application of CEM. It was found that this material dramatically reduced the “T-topping” effect and improved the structural profile angle; and higher aspect ratio microstructures could be achieved without modification/upgrades of any kind on the existing lithography tool. Furthermore, we implemented this process in the fabrication work of high aspect ratio air core solenoid inductor and obtained a very high quality (Q) factor of 72.8 at 9.7 GHz from a 3-turn inductors and a high inductance of 28 nH from a 20-turn inductor. Experimental data showed that inductors with taller via structures (higher aspect ratio) had better radio frequency (RF) characteristics than those of lower via structures, which are highly desirable in many communication applications.

High aspect ratio air core solenoid inductors using an improved UV-LIGA process with contrast enhancement material

High aspect ratio air core solenoid inductors using an improved UV-LIGA process with contrast enhancement material

Effect of contrast material (Levovist) infusion on peak systolic velocity in middle cerebral artery using transcranial color-coded duplex sonography

It is of crucial importance to predict the presence of stenosis in cerebral artery before occurrence of a stroke. To determine stenosis in the middle cerebral artery (MCA), we examined the effect of contrast agent (Levovist) infusion on transcranial color-coded duplex sonography (TCCD). TCCD was performed in 24 patients with MCA stenosis determined by angiography and/or magnetic resonance angiography, and 42 patients without MCA stenosis were also examined as the control group. All patients participated to assess whether an intravenous infusion of contrast agent has some influence on the peak systolic velocity (PSV) measured along the MCA. Videotaping was initiated at the administration of contrast material and continued until contrast was no longer visible in the vessels. PSV values in normal and stenotic vessels were compared. We found that PSVs were significantly higher in the stenosis group than in the control group. Difference between precontrast and postcontrast infusion was significantly greater in the stenosis group than in the control group (p < 0.05). We conclude that PSV tends to be underestimate in poor visualization of vessels. To improve accuracy of PSV measurement, contrast enhancement material should be used.

Synthesis and characterization of water‐soluble diazonium salts as contrast‐enhancement materials

AbstractWater soluble aromatic diazonium double salts, p‐diazodiphenylamine chloride zinc chloride (DZS‐1) and p‐diazoanisol chloride zinc chloride (DZS‐2), have been evaluated as photobleachable dyes for contrast enhancement lithography. After testing the bleaching characteristics, aqueous solutions of DZS‐1 and poly(vinyl alcohol) were used as a contrast enhancement material. Thermal stability, resist contrast, exposure parameters and other bleaching characteristics of the photobleachable membranes were investigated. A. commercial i‐line photoresist was used to evaluate the contrast ratio of the DZS‐1/PVA CEL layer. The contrast ratio obtained in this investigation is 1.67.

Three-dimensional analysis for contrast enhancement lithography by a three-dimensional photolithography simulator

Photoactive parameters of contrast enhancement material CEM 420 for Dill’s model were measured to analyze the contrast enhancement lithography (CEL) process. Then using the three‐dimensional photolithography simulator RESPROT, photoresist images in the CEL process were analyzed and compared with images got in a conventional process. The nature of the photosensitizer concentration distribution in contrast enhancement material (CEM) differs from that in conventional photoresist. The former has a higher contrast distribution. In the CEL process, the sidewall of the photoresist image has a steeper slope than that in the conventional one, and the depth of focus is improved 25% for the former. When defocus is 2.0 μm in the conventional process, the photoresist holes do not open but in the CEL process they do. The contrast of an aerial image in the photomask pattern is improved in the CEL process. For a three‐line pattern in the conventional process, the center photoresist line is narrow and low, but in the CEL process, all three lines have the same height and width. For a double elbow pattern in the conventional process, photoresist thicknesses differ inside and outside of the two elbow photoresist lines after development, however, they are the same in the CEL process.

A direct approach to the modeling of polydihexylsilane as a contrast enhancement material

In our study the polydihexylsilane(PDHS), as a contrast enhancement material, we found that the values of A, B, and C of Dill’s modeling parameters of PDHS are irregularly dependent on its film thickness, and also refractive index decreases during exposure. These difficulties make Dill’s model inadequate for the simulation of contrast enhanced lithography. A new model was derived to simulate the nonlinear photobleaching curves of PDHS with varying thickness. Linearity was found with parameters in this equation as a function of PDHS film thickness. The thicker PDHS film does not improve the contrast within the usually used thickness range of 0.1–0.6 μm. This equation also models the nonlinear bleaching curve of p-diazo-N,N-dimethylaniline-chloride zinc chloride and the reported bleaching curve of CEM-2 quite well.

Application of Photobleachable Positive Resist and Contrast Enhancement Material to KrF Excimer Laser Lithography

In this paper, we present the application of photobleachable positive deep-UV resist and contrast enhancement material (CEM) to KrF excimer laser lithography. The effects of the photobleaching characteristics of the resist and CEM on the resist pattern angles and profiles were examined and optimization of these materials was performed. High-aspect-ratio 0.5 µm-line-and-space patterns were successfully obtained by optimization of the materials. PROLITH (positive resist optical lithography model) has excellently reproduced actual pattern profiles.

Exploration of scattering from topography with massively parallel computers

Rigorous simulation of electromagnetic scattering from wafer topography has been achieved using the massively parallel Connection Machine CM-2. The program, based on a finite-difference time domain algorithm, can be applied to key structures in lithography and alignment with interpenetrating, isolated, or nonperiodic layers while incorporating dynamic effects such as bleaching of photoresist. The accuracy of the program is demonstrated by comparison with results from diffraction gratings analyzed by integral equation methods and by sample simulations of exposure and reflection from dielectric films. Several prototypical two-dimensional problems are explored to demonstrate the capabilities of the method including asymmetry effects in alignment, dynamic exposure near reflective steps, and diffraction in contrast enhancement materials. Steady-state calculations for a 20 λ by 10 λ structure are shown to require approximately 75 s on a prototype 1K processor system with projected performance of &amp;lt;5 s on a fully configured 32K (or larger) machine.