Xenon-Enhanced Dynamic Dual-Energy CT Is Able to Quantify Sinus Ventilation Using Laminar and Pulsating Air-/Gas Flow Before and After Surgery: A Pilot Study in a Cadaver Model.

Background: Chronic rhinosinusitis is a common disease with a significant impact on the quality of life. Topical drug delivery to the paranasal sinuses is not efficient to prevent sinus surgery or expensive biologic treatment in a lot of cases as the affected mucosa is not reached. More efficient approaches for topical drug delivery are, therefore, necessary.

Chest CT using spectral filtration: radiation dose, image quality, and spectrum of clinical utility.

Objectives: To determine the radiation dose, image quality, and clinical utility of non-enhanced chest CT with spectral filtration.

Methods: We retrospectively analysed 25 non-contrast chest CT examinations acquired with spectral filtration (tin-filtered Sn100 kVp spectrum) compared to 25 examinations acquired without spectral filtration (120 kV). Radiation metrics were compared.

Dual-energy CT colonography for preoperative "one-stop" staging in patients with colonic neoplasia.

Rationale And Objectives: To evaluate the benefits of dual-energy computed tomography (CT) colonography (DECTC) as a preoperative staging tool in patients with clinically suspected colorectal cancer (CRC).

Materials And Methods: Twenty-two patients with colorectal neoplasia underwent preoperative abdominal DECTC on a dual-source scanner (SOMATOM Definition Flash; Siemens) operated at tube potentials of Sn140/100 kVp. Scans were evaluated for local tumor stage and the presence of synchronous intracolonic and extracolonic findings using dual-energy color-coded images.

Predictive value of the velocity of collateral filling in patients with acute ischemic stroke.

The velocity of collateral filling can be assessed in dynamic time-resolved computed tomography (CT) angiographies and may predict initial CT perfusion (CTP) and follow-up lesion size. We included all patients with an M1± internal carotid artery (ICA) occlusion and follow-up imaging from an existing cohort of 1791 consecutive patients who underwent multimodal CT for suspected stroke. The velocity of collateral filling was quantified using the delay of time-to-peak (TTP) enhancement of the M2 segment distal to the occlusion.

Dynamic myocardial CT perfusion imaging for evaluation of myocardial ischemia as determined by MR imaging.

Objectives: The aim of this study was to determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the assessment of myocardial ischemia and infarction compared with cardiac magnetic resonance (CMR).

Background: Sequential myocardial CT perfusion imaging has emerged as a novel imaging technique for the assessment of myocardial hypoperfusion.

Methods: We prospectively enrolled subjects with known coronary artery disease who underwent adenosine-mediated stress dynamic dual-source CT (100 kV, 320 mAs/rot) and CMR (3-T).

Non-invasive determination of pulmonary hypertension with dynamic contrast-enhanced computed tomography: a pilot study.

Objectives: In this pilot study we explored whether contrast-material bolus propagation time and speed in the pulmonary arteries (PAs) determined by dynamic contrast-enhanced computed tomography (DCE-CT) can distinguish between patients with and without pulmonary hypertension (PH).

Methods: Twenty-three patients (18 with and 5 without PH) were examined with a DCE-CT sequence following their diagnostic or follow-up right-sided heart catheterisation (RHC). X-ray attenuation over time curves were recorded for regions of interest in the main, right and left PA and fitted with a spline fit.

Molecular imaging based on x-ray fluorescent high-Z tracers.

We propose a novel x-ray fluorescence imaging setup for the in vivo detection of high-Z tracer distributions. The main novel aspect is the use of an analyzer-based, energy-resolved detection method together with a radial, scatter reducing collimator. The aim of this work is to show the feasibility of this method by measuring the Bragg reflected K-fluorescence signal of an iodine solution sample in a proof of principle experiment and to estimate the potential of the complete imaging setup using a Monte Carlo simulation, including a quantification of the minimal detectable tracer concentration for in vivo imaging.

Determination of cardiac output with dynamic contrast-enhanced computed tomography.

Cardiac output (CO) is an important diagnostic and prognostic factor in the haemodynamic evaluation of patients. The gold standard for CO measurement, thermodilution, requires an invasive right-heart catheterisation (RHC). In this pilot study we aimed to determine the accuracy of non-invasive CO determination from dynamic contrast-enhanced computed tomography (CT) compared to thermodilution.

Influence of vascular enhancement, age and gender on pulmonary perfused blood volume quantified by dual-energy-CTPA.

Objectives: To determine the influence of technical and demographic parameters on quantification of pulmonary perfused blood volume (PBV) in dual energy computed tomography pulmonary angiography (DE-CTPA).

Materials And Methods: Pulmonary PBV was quantified in 142 patients who underwent DE-CTPA for suspected pulmonary embolism but in whom no thoracic pathologies were detected. Multivariate linear regression analysis was performed to calculate the influence of age, gender, enhancement of pulmonary trunk and enhancement difference between pulmonary trunk and left atrium (as a measure of timing) on PBV values.

Effectiveness of automated quantification of pulmonary perfused blood volume using dual-energy CTPA for the severity assessment of acute pulmonary embolism.

Purpose: The purpose of this study was to determine whether automated quantification of pulmonary perfused blood volume (PBV) in dual-energy computed tomography pulmonary angiography is of diagnostic value in assessing the severity of acute pulmonary embolism (PE).

Materials And Methods: Ethical approval and informed consent were waived by the responsible institutional review board for this retrospective study. Of 224 consecutive patients with dual-energy computed tomography pulmonary angiographic findings positive for acute PE, we excluded 153 patients because of thoracic comorbidities (n = 130), missing data (n = 11), severe artifacts (n = 11), or inadequate enhancement (n = 1).

Individual patient data meta-analysis for the clinical assessment of coronary computed tomography angiography: protocol of the Collaborative Meta-Analysis of Cardiac CT (CoMe-CCT).

Background: Coronary computed tomography angiography has become the foremost noninvasive imaging modality of the coronary arteries and is used as an alternative to the reference standard, conventional coronary angiography, for direct visualization and detection of coronary artery stenoses in patients with suspected coronary artery disease. Nevertheless, there is considerable debate regarding the optimal target population to maximize clinical performance and patient benefit. The most obvious indication for noninvasive coronary computed tomography angiography in patients with suspected coronary artery disease would be to reliably exclude significant stenosis and, thus, avoid unnecessary invasive conventional coronary angiography.

Assessing pulmonary perfusion in emphysema: automated quantification of perfused blood volume in dual-energy CTPA.

Objectives: The objective of this study was to determine whether automated quantification of lung perfused blood volume (PBV) in dual-energy computed tomographic pulmonary angiography (DE-CTPA) can be used to assess the severity and regional distribution of pulmonary hypoperfusion in emphysema.

Materials And Methods: We retrospectively analyzed 40 consecutive patients (mean age, 67 [13] years) with pulmonary emphysema, who have no cardiopulmonary comorbidities, and a DE-CTPA negative for pulmonary embolism. Automated quantification of global and regional pulmonary PBV was performed using the syngo Dual Energy application (Siemens Healthcare).

Worsening respiratory function in mechanically ventilated intensive care patients: feasibility and value of xenon-enhanced dual energy CT.

Objectives: To evaluate the feasibility and incremental diagnostic value of xenon-enhanced dual-energy CT in mechanically ventilated intensive care patients with worsening respiratory function.

Methods: The study was performed in 13 mechanically ventilated patients with severe pulmonary conditions (acute respiratory distress syndrome (ARDS), n=5; status post lung transplantation, n=5; other, n=3) and declining respiratory function. CT scans were performed using a dual-source CT scanner at an expiratory xenon concentration of 30%.

Dual-energy CT: general principles.

Objective: In dual-energy CT (DECT), two CT datasets are acquired with different x-ray spectra. These spectra are generated using different tube potentials, partially also with additional filtration at 140 kVp. Spectral information can also be resolved by layer detectors or quantum-counting detectors.

Dual-energy CT for the evaluation of silicone breast implants.

Objective: The evaluation of breast implants for rupture is currently the domain of ultrasound and MRI, while mammography is of very limited diagnostic value. Recently, specific visualisation of silicone has become feasible using dual-energy CT. Our objective was to evaluate whether it is feasible to identify silicone in breast implants by dual-energy CT and to reliably diagnose or rule out ruptures.

Imaging evaluation of acute chest pain: systematic review of evidence base and cost-effectiveness.

Given the often inconclusive initial evaluation of patients presenting with acute chest pain in the Emergency Department, advanced imaging techniques have been evaluated in the quest for improving the current standard of care. In this article, we systematically compare and evaluate the available evidence and cost-effectiveness of radionucleotide myocardial perfusion imaging, cardiac computed tomography angiography, and cardiac magnetic resonance imaging using data from PubMed and EMBASE through January 2012. The obtained data were summarized and categorized according to the reached level of evidence and its impact on the decision-making process.

Metal artifact reduction by dual-energy computed tomography using energetic extrapolation: a systematically optimized protocol.

Objectives: Energetic extrapolation is a promising strategy to reduce metal artifacts in dual-source computed tomography (DSCT). We performed this study to systematically optimize image acquisition parameters for this approach in a hip phantom and assess its value in a clinical study.

Materials And Methods: Titanium and steel hip prostheses were placed in a standard hip phantom and a water tank and scanned on a DSCT scanner.

Time-resolved CT angiography for the detection and classification of endoleaks.

Purpose: To assess the feasibility and diagnostic performance of time-resolved computed tomographic (CT) angiography in the detection and classification of endoleaks after endovascular aortic aneurysm repair (EVAR) in high-risk patients.

Materials And Methods: The study was approved by our ethics committee. Written informed consent was obtained from all participating patients.

Ventilation imaging of the paranasal sinuses using xenon-enhanced dynamic single-energy CT and dual-energy CT: a feasibility study in a nasal cast.

Objective: To show the feasibility of dual-energy CT (DECT) and dynamic CT for ventilation imaging of the paranasal sinuses in a nasal cast.

Methods: In a first trial, xenon gas was administered to a nasal cast with a laminar flow of 7 L/min. Dynamic CT acquisitions of the nasal cavity and the sinuses were performed.

Diagnostic accuracy of dynamic computed tomographic angiographic of the lower leg in patients with critical limb ischemia.

Objective: The purpose of this study was to assess the diagnostic accuracy of dynamic computed tomographic angiography (dyn-CTA) in patients with critical lower leg ischemia.

Materials And Methods: A population of 29 patients with known peripheral arterial occlusive disease (Fontaine stage III or IV) was examined with a combined CTA protocol consisting of a standard CTA (s-CTA) of the lower leg runoff from the diaphragm to the toes and dyn-CTA of the calves (scan range, 48 cm; 8 phases; 3.5 seconds per phase, 100 kV; 120 mAs; contrast volume, 50 mL; flow rate, 5.

Accuracy of dynamic computed tomography adenosine stress myocardial perfusion imaging in estimating myocardial blood flow at various degrees of coronary artery stenosis using a porcine animal model.

Objective: To determine the accuracy of computed tomography (CT) dynamic stress myocardial perfusion imaging to estimate myocardial blood flow (MBF) in a porcine animal model with variable degrees of induced coronary artery stenosis in comparison with microsphere-derived MBF.

Methods And Materials: Seven domestic pigs (36 ± 4 kg) received stents (confirmed 3.0 mm diameter) in the left anterior descending coronary artery distal to first diagonal branch.

Severity assessment of pulmonary embolism using dual energy CT - correlation of a pulmonary perfusion defect score with clinical and morphological parameters of blood oxygenation and right ventricular failure.

Objective: To correlate a Dual Energy (DE)-based visual perfusion defect scoring system with established CT-based and clinical parameters of pulmonary embolism (PE) severity.

Methods: In 63 PE patients, DE perfusion maps were visually scored for perfusion defects (P-score). Vascular obstruction was quantified using the Mastora score.

Detection of hemodynamically significant coronary artery stenosis: incremental diagnostic value of dynamic CT-based myocardial perfusion imaging.

Purpose: To determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the detection of hemodynamically significant coronary artery stenosis, as defined with fractional flow reserve (FFR).

Materials And Methods: Institutional review board approval and informed patient consent were obtained before patient enrollment in the study. The study was HIPAA compliant.

Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation.

Objective: The aim of the study was to assess the performance and diagnostic value of a dual energy CT approach to reduce metal artefacts in subjects with metallic implants.

Methods: 31 patients were examined in the area of their metallic implants using a dual energy CT protocol (filtered 140 kVp and 100 kVp spectrum, tube current relation: 3:1). Specific post-processing was applied to generate energies of standard 120 and 140 kVp spectra as well as a filtered 140 kVp spectrum with mean photon energies of 64, 69 and 88 keV, respectively, and an optimized hard spectrum of 95-150 keV.

Diagnostic image quality of a comprehensive high-pitch dual-spiral cardiothoracic CT protocol in patients with undifferentiated acute chest pain.

Objective: To evaluate diagnostic image quality of high-pitch dual source comprehensive cardiothoracic CT protocol in patients presenting with acute undifferentiated chest pain.

Materials And Methods: Consecutive symptomatic subjects (n=51) with undifferentiated acute chest pain underwent ECG-synchronized high-pitch dual-spiral chest CT angiography (Definition Flash, Siemens Medical Solutions, 2 × 100 kVp or 2 × 120 kV if BMI>30, collimation: 128 × 0.6mm, pitch: 3.