Clinical Applications of Dual Energy CT in Neuroradiology
Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski in Spectral, Photon Counting Computed Tomography, 2020
Dual Energy Computed Tomography (DECT), a special case of general-purpose multispectral CT, has emerged as a valuable adjunct to single-energy CT in multiple clinical applications in neuroradiology. This chapter briefly discusses the various architectures used for implementing DECT. Low- and high-energy images from DECT acquisitions are post-processed using models that incorporate the dependence of x-ray attenuation on photon energy as dictated by the photoelectric effect and Compton scattering. It describes post-processing techniques used in DECT and illustrates them with useful and promising applications in neuroradiology. The chapter discusses the pertinent literature and also describes the application with examples from routine clinical care of patients. As an x-ray beam travels through the body it is attenuated by the various tissues it encounters in its path. A map of this attenuation forms the basis of both projection radiography and cross-sectional CT.
Tomography Reconstructions With Stochastic Level-Set Methods
Ayman El-Baz, Jasjit S. Suri in Level Set Method in Medical Imaging Segmentation, 2019
This chapter shows that the type of approach can be generalized to inverse problems with piecewise constant solutions. It summarizes some results about stochastic calculus and the level-set regularization of inverse problems. The stochastic level-set approach is applied to the binary tomography and to the phase contrast tomography inverse problem. The chapter presents the level-set regularization approach of inverse problems and some aspects of stochastic calculus and the level-set regularization approach of inverse problems. It explains the difference between the Ito and Stratonovich stochastic integrals and the deterministic level-set algorithm with the modified algorithms with the stochastic evolution. The tomographic reconstruction from few projections is a very ill-posed problem with many applications in medical imaging or material science. X-ray in-line phase contrast tomography is a very sensitive technique for soft tissues within dense materials. Stochastic level-set evolution the deterministic optimization of the level-set function is often stopped in local minima.
Liver and biliary system, pancreas and spleen
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha in Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
Ultrasound is less sensitive than computed tomography (CT) or magnetic resonance imaging (MRI) at detection of diffuse liver diseases and widespread abnormalities such as hepatitis, but National Institute for Health and Care Excellence guidelines suggest its use for monitoring cirrhosis associated with hepatitis B. CT will also detect biliary dilatation and often reveal the cause when ultrasound is unable to do so, e.g. distal common bile duct stone and pancreatic head mass. In an acute setting CT can detect and characterise laceration and haematoma of the liver in trauma, and liver and subphrenic abscess causing acute sepsis. MRI demonstrates the pancreas well but may not practicable or readily available in acutely ill patients with severe pancreatitis where CT remains the predominant modality. MRI can also be used to detect and assess liver masses but is usually a second- or third-line test used when other modalities are inconclusive.
Problems and Solutions in 3-D Analysis of Phase Biological Objects by Optical Diffraction Tomography
Published in International Journal of Optomechatronics, 2014
Małgorzata Kujawińska, Wojciech Krauze, Arkadiusz Kus, Julianna Kostencka, Tomasz Kozacki, Björn Kemper, Michał Dudek
Optical Diffraction Tomography is a technique for retrieving a 3-dimensional refractive index distribution from phase objects without destroying the structure of the samples. In the article we discuss the selection and implementation of full and limited angle version of tomographic reconstruction processes together with the analysis of different methods for gathering projections. We present two efficient implementations of full and limited angle tomographic systems including total processing paths and providing the examplary results of 3-D refractive index determination measurements of biological samples.
Detection of noncalcified and mixed plaque by multirow detector computed tomography
Published in Expert Review of Cardiovascular Therapy, 2009
Gary Foster, Harsh Shah, Guilda Sarraf, Naser Ahmadi, Matthew Budoff
New tomographic cardiovascular imaging tests, such as intravascular ultrasonography and coronary computed tomography angiography, can be used to assess atherosclerotic plaques for the characterization and early staging of coronary artery disease (CAD). Although intravascular ultrasonography provides high-resolution images that are capable of revealing early preclinical CAD, it is a highly invasive technique used clinically only in conjunction with coronary interventions. Multidetector computed tomography angiography, which is noninvasive and corresponds well with plaque histology, shows promise as a diagnostic method for CAD and can provide general evaluation of noncalcified and mixed plaque composition. The current generation of 64-slice computed tomography scanners have high accuracy for detection of lesions obstructing more than 50% of the lumen, with sensitivity, specificity, and positive and negative predictive values all over 90% in patients without known CAD. They may have an important role in characterizing high-risk noncalcified and mixed plaques. Review of the currently available literature suggests that tissue density measured by multidetector computed tomography can be used to accurately characterize coronary atherosclerotic plaque composition. With further advances in tomographic angiography, the goal will be to detect plaques earlier in the development of CAD and to characterize the plaques most likely to generate a clinical event.
Macular Involvement and Response to Steroid Therapy Demonstrated by Optical Coherence Tomography in Non-arteritic Anterior Ischaemic Optic Neuropathy
Published in Neuro-Ophthalmology, 2013
Sibel Demirel, Figen Batıoğlu, Yesim Gedik Oguz, Emin Özmert
Two consecutive patients with anterior non-arteritic ischaemic optic neuropathy were evaluated with spectral-domain optical coherence tomography. The optical coherence tomographic scans revealed subfoveal fluid and intraretinal fluid extending from the optic disc margin toward the fovea that made us think that the submacular fluid appeared to arise from the peripapillary region. Fluorescein angiography showed no accumulation in the macular area, whereas leakage and staining of the optic nerve was present. After systemic corticosteroid therapy, the submacular fluid decreased promptly and the visual acuity improved. Subretinal-fluid-associated disc oedema may develop in some patients with NAION and contribute to the visual loss associated with this condition. Optical coherence tomography should be performed to follow macular involvement in patients with neuro-ophthalmic disease as well as to monitor patients’ response to treatment.
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