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Computed tomography (CT) colonography has demonstrated efficacy for the detection of clinically significant Technologic advances, including multidetector scanners and computer-aided detection, will increase the sensitivity of dete...
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Computed tomography (CT) colonography has demonstrated efficacy for the detection of clinically significant Technologic advances, including multidetector scanners and computer-aided detection, will increase the sensitivity of detection and decrease the time for interpretation of this study. Fecal tagging may allow for the elimination of a bowel-cleansing regimen, which is currently a major factor in patient noncompliance. The combination of these expected advances promises to make CT colonography a viable option for population screening. The purpose of this article is to review the development of CT colonography, evaluate its efficacy, and to examine the future applications of this technique.
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Some subtle CT findings in the brain can present a challenge to the radiologist, and obvious abnormalities may be misdiagnosed. Cases are categorized into cerebrovascular event, venous thrombosis, posttraumatic evaluation, evaluat...
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Some subtle CT findings in the brain can present a challenge to the radiologist, and obvious abnormalities may be misdiagnosed. Cases are categorized into cerebrovascular event, venous thrombosis, posttraumatic evaluation, evaluation of subarachnoid hemorrhage, and meningoencephalitis. Accurate and early diagnosis of these entities allows rapid triage with appropriate management and better prognosis.
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Purpose of Review The purpose of this paper is to review the current role of computed tomography (CT) in the imaging of left ventricular assist devices (LVAD). Recent Findings Recent studies have highlighted the prognostic role of...
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Purpose of Review The purpose of this paper is to review the current role of computed tomography (CT) in the imaging of left ventricular assist devices (LVAD). Recent Findings Recent studies have highlighted the prognostic role of measuring skeletal muscle CT attenuation in predicting adverse LVAD outcomes. CT is also useful for evaluation of inflow cannula malposition, and outflow graft complications such as obstruction and kinking. In addition,F-18-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) has been shown to be of value in evaluation of suspected LVAD infection. Newer CT techniques such as dual-energy CT and metal artifact reduction algorithms can potentially generate better quality CT images, though currently there is no high-quality published literature on their use in LVAD imaging. CT is a useful technique as part of a multi-modality approach in the evaluation of LVADs and associated complications.
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Coronary artery disease is the leading cause of morbidity and mortality in the United States. Both electron beam computed tomography (CT) and multidetector row CT can produce diagnostic quality images of the coronary arteries foll...
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Coronary artery disease is the leading cause of morbidity and mortality in the United States. Both electron beam computed tomography (CT) and multidetector row CT can produce diagnostic quality images of the coronary arteries following intravenous injection of contrast material. Speed and appropriate timing of image acquisition are key determinants of successful technique, and familiarity with the electromechanical relationship of the electrocardiogram (ECG) tracing to the cardiac cycle is fundamental to understanding the protocol. Images may be used to diagnose coronary artery atherosclerotic disease and pathologic states of coronary anatomy, to document the patency of bypass grafts and intraluminal stents, and to derive data regarding the functional status of the heart. This paper will review the technologic and physiologic principles fundamental to imaging coronary arteries with CT.
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Image quality in computed tomographic angiography (CTA) is critically dependent on contrast injection, data acquisition, and postprocessing technique. First, injection parameters are chosen to achieve intense homogeneous enhanceme...
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Image quality in computed tomographic angiography (CTA) is critically dependent on contrast injection, data acquisition, and postprocessing technique. First, injection parameters are chosen to achieve intense homogeneous enhancement despite inter-individual hemodynamic variability. Next, CT data acquisition must obtain adequately thin sections over the appropriate volume of interest during a limited temporal scanning window. Finally, reconstruction and rendering techniques must be rationally selected to demonstrate relevant anatomy and disease processes in an accurate manner. Advances in these areas and in scanner technology will enable the development of new applications. This article provides a primer for conceptual understanding of parameters that allow optimization of CTA studies.
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Twenty-six consecutive patients with the clinical diagnosis of appendicitis underwent multidetectorrow CT (MD-CT) in order to detect entire longitudinal configuration of the appendix. While axial CT failed to detect the appendix i...
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Twenty-six consecutive patients with the clinical diagnosis of appendicitis underwent multidetectorrow CT (MD-CT) in order to detect entire longitudinal configuration of the appendix. While axial CT failed to detect the appendix in 7 patients, multiplanar reconstruction (MPR) demonstrated a longitudinal tubular structure continuous from the cecal caput in 25 patients (96.2%), including 7 patients whose post-surgical pathology were available. It is summarized that scanning and MPR images are advantageous to finding inflammatory processes in the appendix when the diagnosis of appendicitis remains ambiguous even with US.
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Portal hypertension secondary to liver cirrhosis may cause a number of life-threatening complications. The rupture of gastroesophageal varices is associated with a high mortality rate of 15-30%. Hepatic venous pressure gradient (H...
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Portal hypertension secondary to liver cirrhosis may cause a number of life-threatening complications. The rupture of gastroesophageal varices is associated with a high mortality rate of 15-30%. Hepatic venous pressure gradient (HVPG) is an accurate reflection of disease severity, however this can only be assessed via an invasive interventional procedure. The aim of the present study was to explore a non-invasive method based on 3D computed tomography (CT) volume rendering technology to accurately predict HVPG. A total of 77 patients diagnosed with liver cirrhosis underwent HVPG examination in the present study and the appropriate clinical and radiological data were retrospectively reviewed. A 3D liver and spleen volume rendering was constructed for volume measurements. All non-invasive parameters were tested using univariate analysis and the resulting variables that were statistically significant (P<0.20) were used in the multivariate linear regression model. The HVPG predictive model was as follows: HVPG = 18.726 - 0.324 (albumin) + 1.57 (aminotransferase-to-platelet ratio index) + 0.004 (liver volume) (multivariate regression analysis, P=0.006). The corresponding area under receiver operating characteristic curve to identify clinically significant portal hypertension defined as HVPG 10 mmHg was 0.810 (95% confidence interval; 0.705-0.891), with an optimal cut-off value of 12.84, yielding a sensitivity of 80.36% a specificity of 76.19%. The results of the present study indicate that 3D CT volume rendering technology may have the potential to be used for non-invasive prediction of HVPG.
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The CT data acquired in combined PET/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the ra...
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The CT data acquired in combined PET/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the range of 40-140 keV must be transformed into linear attenuation coefficients at the PET energy of 511 keV. As attenuation depends on photon energy and the absorbing material, an accurate theoretical relation cannot be devised. The transformation implemented in the Discovery LS PET/CT scanner (GE Medical Systems, Milwaukee, Wis.) uses a bilinear function based on the attenuation of water and cortical bone at the CT and PET energies. The purpose of this study was to compare this transformation with experimental CT values and corresponding PET attenuation coefficients. In 14 patients, quantitative PET attenuation maps were calculated from germanium-68 transmission scans, and resolution-matched CT images were generated. A total of 114 volumes of interest were defined and the averagePET attenuation coefficients and CT values measured. From the CT values the predicted PET attenuation coefficients were calculated using the bilinear transformation. When the transformation was based on the narrow-beam attenuation coefficient of water at 511 keV (0.096 cm-1), the predicted attenuation coefficients were higher in soft tissue than the measured values. This bias was reduced by replacing 0.096 cm-1 in the transformation by the linear attenuation coefficient of 0.093 cm-1 obtained from germanium-68 transmission scans. An analysis of the corrected emission activities shows that the resulting transformation is essentially equivalent to the transmission-based attenuation correction for human tissue. For non-human material, however, it may assign inaccurate attenuation coefficients which will also affect the correction in neighbouring tissue.
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Combined assessment of three dimensional anatomical and functional images (SPECT, PET, MRI, CT) is useful to determine the nature and extent of lesions in may parts of the body. Physicians principally rely on their spatial sense t...
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Combined assessment of three dimensional anatomical and functional images (SPECT, PET, MRI, CT) is useful to determine the nature and extent of lesions in may parts of the body. Physicians principally rely on their spatial sense to mentally re-orient and overlap images obtained with different imaging modalities. Objective methods that enable easy and intuitive image registration can help the physician arrive at more optimal diagnoses and better treatment decisions. This review describes a sim- ple, intuitive and robust image registration approach developed in our laboratory.
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First-pass perfusion computed tomography (CT) and CT angiography (CTA) can evaluate brain ischemia and large vessel patency rapidly using the same imaging equipment often used in the initial evaluation of stroke. While magnetic re...
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First-pass perfusion computed tomography (CT) and CT angiography (CTA) can evaluate brain ischemia and large vessel patency rapidly using the same imaging equipment often used in the initial evaluation of stroke. While magnetic resonance (MR) diffusion and perfusion techniques hold great promise in the setting of cerebral ischemia/infarction, this promise has not been realize, due in part to a lack of widespread 24-hour availability of MR equipment. This paper reviews the use of contrast-enhanced CT studies to provide needed information within a relevant time frame to tailor appropriate treatment for victims of cerebral vascular accidents. Reviewed studies will demonstrate that these techniques triage patients quickly for current treatment regimens and soon may provide the basis for thrombolytic treatment regimens outside of the 6-hour limit currently advocated.
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