A new iterative algorithm for ring artifact reduction in CT using ring total variation.

Purpose: In computed tomography (CT), miscalibrated or imperfect detector elements produce stripe artifacts in the sinogram. The stripe artifacts in Radon space are responsible for concentric ring artifacts in the reconstructed images. In this work, a novel optimization model is proposed to remove the ring artifacts in an iterative reconstruction procedure.

An Intravascular Tantalum Oxide-based CT Contrast Agent: Preclinical Evaluation Emulating Overweight and Obese Patient Size.

Purpose To compare the CT imaging performance of a carboxybetaine zwitterionic-coated tantalum oxide (TaCZ) nanoparticle CT contrast agent with that of a conventional iodinated contrast agent in a swine model meant to simulate overweight and obese patients. Materials and Methods Four swine were evaluated inside three different-sized adipose-equivalent encasements emulating abdominal girths of 102, 119, and 137 cm. Imaging was performed with a 64-detector row CT scanner at six scan delays after intravenous injection of 240 mg element (Ta or I) per kilogram of body weight of TaCZ or iopromide.

Liquid tissue surrogates for X-ray and CT phantom studies.

Purpose: To develop a simple method for producing liquid-tissue-surrogate (LTS) materials that accurately represent human soft tissues in terms of density and X-ray attenuation coefficient.

Methods And Materials: We evaluated hypothetical mixtures of water, glycerol, butanol, methanol, sodium chloride, and potassium nitrate; these mixtures were intended to emulate human adipose, blood, brain, kidney, liver, muscle, pancreas, and skin. We compared the hypothetical densities, effective atomic numbers (Z ), and calculated discrete-energy CT attenuation [Hounsfield Units (HU)] of the proposed materials with those of human tissue elemental composition as specified in International Commission on Radiation Units (ICRU) Report 46.

Quest for the ultimate cardiac CT scanner.

Purpose: To quantitatively evaluate and compare six proposed system architectures for cardiac CT scanning.

Methods: Starting from the clinical requirements for cardiac CT, we defined six dedicated cardiac CT architectures. We selected these architectures based on a previous screening study and defined them in sufficient detail to comprehensively analyze their cost and performance.

The Effect of Patient Diameter on the Dual-Energy Ratio of Selected Contrast-Producing Elements.

Objectives: The aim of this study was to assess whether the low- to high-kVp computed tomography (CT) number ratio at dual-energy CT is affected by changes in patient diameter.

Methods: Seven contrast-producing elements were housed sequentially within an abdomen phantom. Fat rings enlarged the phantom diameter from 26 to 44 cm.

Opportunities for new CT contrast agents to maximize the diagnostic potential of emerging spectral CT technologies.

The introduction of spectral CT imaging in the form of fast clinical dual-energy CT enabled contrast material to be differentiated from other radiodense materials, improved lesion detection in contrast-enhanced scans, and changed the way that existing iodine and barium contrast materials are used in clinical practice. More profoundly, spectral CT can differentiate between individual contrast materials that have different reporter elements such that high-resolution CT imaging of multiple contrast agents can be obtained in a single pass of the CT scanner. These spectral CT capabilities would be even more impactful with the development of contrast materials designed to complement the existing clinical iodine- and barium-based agents.

Multisource inverse-geometry CT. Part II. X-ray source design and prototype.

Purpose: This paper summarizes the development of a high-power distributed x-ray source, or "multisource," designed for inverse-geometry computed tomography (CT) applications [see B. De Man et al., "Multisource inverse-geometry CT.

Cardiac CT: A system architecture study.

Background: We are interested in exploring dedicated, high-performance cardiac CT systems optimized to provide the best tradeoff between system cost, image quality, and radiation dose.

Objective: We sought to identify and evaluate a broad range of CT architectures that could provide an optimal, dedicated cardiac CT solution.

Methods: We identified and evaluated thirty candidate architectures using consistent design choices.

Complementary contrast media for metal artifact reduction in dual-energy computed tomography.

Metal artifacts have been a problem associated with computed tomography (CT) since its introduction. Recent techniques to mitigate this problem have included utilization of high-energy (keV) virtual monochromatic spectral (VMS) images, produced via dual-energy CT (DECT). A problem with these high-keV images is that contrast enhancement provided by all commercially available contrast media is severely reduced.

CT Image Contrast of High-Z Elements: Phantom Imaging Studies and Clinical Implications.

Purpose: To quantify the computed tomographic (CT) image contrast produced by potentially useful contrast material elements in clinically relevant imaging conditions.

Materials And Methods: Equal mass concentrations (grams of active element per milliliter of solution) of seven radiodense elements, including iodine, barium, gadolinium, tantalum, ytterbium, gold, and bismuth, were formulated as compounds in aqueous solutions. The compounds were chosen such that the active element dominated the x-ray attenuation of the solution.

Acquisition, preprocessing, and reconstruction of ultralow dose volumetric CT scout for organ-based CT scan planning.

Purpose: Traditionally, 2D radiographic preparatory scan images (scout scans) are used to plan diagnostic CT scans. However, a 3D CT volume with a full 3D organ segmentation map could provide superior information for customized scan planning and other purposes. A practical challenge is to design the volumetric scout acquisition and processing steps to provide good image quality (at least good enough to enable 3D organ segmentation) while delivering a radiation dose similar to that of the conventional 2D scout.

Feasibility study on ultra-low dose 3D scout of organ based CT scan planning.

3D volumetric CT images hold the potential to become a rich source of information for 3D organ segmentation and far exceed that made available through 2D radiograph images. Acquiring and generating 3D volumetric images for scan preparation purposes, i.e.

A Fourier-domain algorithm for total-variation regularized phase retrieval in differential X-ray phase contrast imaging.

Phase retrieval in differential X-ray phase contrast imaging involves a one dimensional integration step. In the presence of noise, standard integration methods result in image blurring and streak artifacts. This work proposes a regularized integration method which takes the availability of two dimensional data as well as the integration-specific frequency-dependent noise amplification into account.

Future generation CT imaging.

X-ray CT technology has been available for more than 30 years, yet continued technological advances have kept CT imaging at the forefront of medical imaging innovation. Consequently, the number of clinical CT applications has increased steadily. Other imaging modalities might be superior to CT imaging for some specific applications, but no other single modality is more often used in chest imaging today.

Gauging effective spatial resolution in multirow helical cardiac computed tomography with a dynamic phantom.

Purpose: To devise a numerical indicator of image quality for multirow helical cardiac computed tomography (CT) and its relation to temporal resolution.

Materials And Methods: A pulsatile cardiac assist device was used to simulate cardiac wall motion by mechanically transmitting the device dynamics to a piece of tungsten wire. Wire motion induced by different device rates was captured with an 8-row subsecond helical CT scanner operating with various scanning parameters.