Feasibility of dual-energy CT in the arterial phase: Imaging after endovascular aortic repair.

Objective: The purpose of this study was to investigate replacing unenhanced and arterial single-energy CT acquisitions after endovascular aneurysm repair with one dual-energy CT arterial acquisition.

Subjects And Methods: Thirty patients underwent arterial dual-energy CT (80 and 140 kVp) and venous single-energy CT (120 kVp) after endovascular aneurysm repair, and the radiation doses were compared with those of a standard triple-phase protocol. Both virtual unenhanced and arterial images were generated with dual-energy CT.

Dual-source computed tomographic temporal resolution provides higher image quality than 64-detector temporal resolution at low heart rates.

Objective: To compare coronary image quality at temporal resolutions associated with dual-source computed tomography (DSCT; 83 milliseconds) and 64-detector row scanning (165 milliseconds).

Methods: In 30 patients with a heart rate of less than 70 beats per minute, DSCT coronary angiograms were reconstructed at 83- and 165-millisecond temporal resolutions over different cardiac phases. A blinded observer graded coronary quality.

Adaptive Bolus Chasing Computed Tomography Angiography: Control Scheme and Experimental Results.

In this paper, a new adaptive bolus-chasing control scheme is proposed to synchronize the bolus peak in a patient's vascular system and the imaging aperture of a computed tomography (CT) scanner. The proposed control scheme is theoretically evaluated and experimentally tested on a modified Siemens SOMATOM Volume Zoom CT scanner. The first set of experimental results are reported on bolus-chasing CT angiography using realistic bolus dynamics, real-time CT imaging and adaptive table control with physical vasculature phantoms.

Optimal image reconstruction phase at low and high heart rates in dual-source CT coronary angiography.

The purpose of this study was to determine the cardiac phase having the highest coronary sharpness for low and high heart rate patients scanned with dual source CT (DSCT) and to compare coronary image sharpness over different cardiac phases. DSCT coronary CT scans for 30 low heart rate (< or =70 beats per minute- bpm) and 30 high heart rate (>70 bpm) patients were reconstructed into different cardiac phases, starting at 30% and increasing at 5% increments until 70%. A blinded observer graded image sharpness per coronary segment, from which sharpness scores were produced for the right (RCA), left main (LM), left anterior descending (LAD), and circumflex (Cx) coronary arteries.

Correlation of histological findings from a large ciliochoroidal melanoma with CT perfusion and 3T MRI dynamic enhancement studies.

Background: The initial use of a 64-slice computed tomography (CT) scanner for obtaining quantitative perfusion data from a large ciliochoroidal melanoma, and correlation with 3T magnetic resonance imaging (MRI) dynamic enhancement and tumor histology.

Methods: The CT perfusion scan was performed using 80 kVp, 250 mA and 1-sec rotation time for 40 sec. The analysis was performed using commercial perfusion analysis software with a prototype 3-dimensional motion correction tool.

CT-measured regional specific volume change reflects regional ventilation in supine sheep.

Computer tomography (CT) imaging techniques permit the noninvasive measurement of regional lung function. Regional specific volume change (sVol), determined from the change in lung density over a tidal breath, should correlate with regional ventilation and regional lung expansion measured with other techniques. sVol was validated against xenon (Xe)-CT-specific ventilation (sV) in four anesthetized, intubated, mechanically ventilated sheep.

Dose performance of a 64-channel dual-source CT scanner.

Purpose: To prospectively compare the dose performance of a 64-channel multi-detector row computed tomographic (CT) scanner and a 64-channel dual-source CT scanner from the same manufacturer.

Materials And Methods: To minimize dose in the cardiac (dual-source) mode, the evaluated dual-source CT system uses a cardiac beam-shaping filter, three-dimensional adaptive noise reduction, heart rate-dependent pitch, and electrocardiographically based modulation of the tube current. Weighted CT dose index per 100 mAs was measured for the head, body, and cardiac beam-shaping filters.

A segmentation-based method for metal artifact reduction.

Rationale And Objectives: We propose a novel segmentation-based interpolation method to reduce the metal artifacts caused by surgical aneurysm clips.

Materials And Methods: Our method consists of five steps: coarse image reconstruction, metallic object segmentation, forward-projection, projection interpolation, and final image reconstruction. The major innovations are 2-fold.

Effect of low-xenon and krypton supplementation on signal/noise of regional CT-based ventilation measurements.

Xenon computed tomography (Xe-CT) is used to estimate regional ventilation by measuring regional attenuation changes over multiple breaths while rebreathing a constant Xe concentration ([Xe]). Xe-CT has potential human applications, although anesthetic properties limit [Xe] to View Article and Find Full Text PDF

Projection-based bolus detection for computed tomographic angiography.

Computed tomographic (CT) angiography is important for imaging studies on cardiovascular structures, peripheral vessels, and solid organs. In practice, a CT angiography scan is triggered by the bolus arrival at a prespecified anatomical location, which is determined using CT fluoroscopy. In this article, we propose a projection-based method adapted from the Grangeat formula to detect the bolus arrival.

Static versus prospective gated non-breath hold volumetric MDCT imaging of the lungs.

Rationale And Objectives: The study's aim is to establish lung-imaging methods that provide for the ability to image the lung under dynamic non-breath hold conditions while providing "virtual breath hold" quantifiable volumetric image data sets. Static breath hold images are used as the gold standard for evaluating these virtual breath hold images in both a phantom and sheep.

Materials And Methods: Axial methods for gating image acquisition to multiple points in the respiratory cycle interleaved with incremental table stepping during multidetector-row computed tomographic (MDCT) scanning were developed.

Differences in regional wash-in and wash-out time constants for xenon-CT ventilation studies.

Unlabelled: Xenon-enhanced computed tomography (Xe-CT) has been used to measure regional ventilation by determining the wash-in (WI) and wash-out (WO) rates of stable Xe. We tested the common assumption that WI and WO rates are equal by measuring WO-WI in different anatomic lung regions of six anesthetized, supine sheep scanned using multi-detector-row computed tomography (MDCT). We further investigated the effect of tidal volume, image gating (end-expiratory EE versus end-inspiratory EI), local perfusion, and inspired Xe concentration on this phenomenon.

High-resolution computed tomography imaging of airway disease in infants with cystic fibrosis.

Rationale: The development of early lung disease in patients with cystic fibrosis (CF) remains poorly defined.

Objective: Determine whether asymptomatic infants with CF have evidence for changes in airway structure when assessed by high-resolution computed tomography, and whether airway structure correlates with airway function in this age group.

Methods: Thirteen infants with CF (8-33 mo) and 13 control infants (7-25 mo) were evaluated.

Characterization of the interstitial lung diseases via density-based and texture-based analysis of computed tomography images of lung structure and function.

Rationale And Objectives: Efforts to establish a quantitative approach to the computed tomography (CT)-based character ization of the lung parenchyma in interstitial lung disease (including emphysema) has been sought. The accuracy of these tools must be site independent. Multi-detector row CT has remained the gold standard for imaging the lung, and it provides the ability to image both lung structure as well as lung function.

Maximizing quantitative accuracy of lung airway lumen and wall measures obtained from X-ray CT imaging.

To objectively quantify airway geometry from three-dimensional computed tomographic (CT) images, an idealized (circular cross section) airway model is parameterized by airway luminal caliber, wall thickness, and tilt angle. Using a two-dimensional CT slice, an initial guess for the airway center, and the full-width-half-maximum principle, we form an estimate of inner and outer airway wall locations. We then fit ellipses to the inner and outer airway walls via a direct least squares fit and use the major and minor axes of the ellipses to estimate the tilt and in-plane rotation angles.