Regional Lung Perfusion Analysis in Experimental ARDS by Electrical Impedance and Computed Tomography.

Electrical impedance tomography is clinically used to trace ventilation related changes in electrical conductivity of lung tissue. Estimating regional pulmonary perfusion using electrical impedance tomography is still a matter of research. To support clinical decision making, reliable bedside information of pulmonary perfusion is needed.

Metal Artifact Reduction Computed Tomography of Arthroplasty Implants: Effects of Combined Modeled Iterative Reconstruction and Dual-Energy Virtual Monoenergetic Extrapolation at Higher Photon Energies.

Objective: The aim of this study was to compare the effects of combined virtual monoenergetic extrapolation (VME) of dual-energy computed tomography data and iterative metal artifact reduction (iMAR) at higher photon energies on low- and high-density metal artifacts and overall image quality of the ankle arthroplasty implants with iMAR, weighted filtered back projection (WFBP), and WFBP-based VME.

Materials And Methods: Total ankle arthroplasty implants in 6 human cadaver ankles served as surrogates for arthroplasty implants. All specimens underwent computed tomography with a 2 × 192-slice dual-source computed tomography scanner at tube voltages of 80 and tin-filtered 150 kVp to produce mixed 120 kVp equivalent polychromatic and virtual monoenergetic extrapolated images at 150 and 190 keV (VME 150 and VME 190, respectively).

"X-Map 2.0" for Edema Signal Enhancement for Acute Ischemic Stroke Using Non-Contrast-Enhanced Dual-Energy Computed Tomography.

Objectives: A novel imaging technique ("X-map") has been developed to identify acute ischemic lesions for stroke patients using non-contrast-enhanced dual-energy computed tomography (NE-DE-CT). Using the 3-material decomposition technique, the original X-map ("X-map 1.0") eliminates fat and bone from the images, suppresses the gray matter (GM)-white matter (WM) tissue contrast, and makes signals of edema induced by severe ischemia easier to detect.

Assessment of iodine uptake by pancreatic cancer following chemotherapy using dual-energy CT.

Pancreatic cancer remains a major health problem, and only less than 20% of patients have resectable disease at the time of initial diagnosis. Systemic chemotherapy is often used in the patients with borderline resectable, locally advanced unresectable disease and metastatic disease. CT is often used to assess for therapeutic response; however, conventional imaging including CT may not correctly reflect treatment response after chemotherapy.

Standardizing CT lung density measure across scanner manufacturers.

Purpose: Computed Tomography (CT) imaging of the lung, reported in Hounsfield Units (HU), can be parameterized as a quantitative image biomarker for the diagnosis and monitoring of lung density changes due to emphysema, a type of chronic obstructive pulmonary disease (COPD). CT lung density metrics are global measurements based on lung CT number histograms, and are typically a quantity specifying either the percentage of voxels with CT numbers below a threshold, or a single CT number below which a fixed relative lung volume, nth percentile, falls. To reduce variability in the density metrics specified by CT attenuation, the Quantitative Imaging Biomarkers Alliance (QIBA) Lung Density Committee has organized efforts to conduct phantom studies in a variety of scanner models to establish a baseline for assessing the variations in patient studies that can be attributed to scanner calibration and measurement uncertainty.

Low-dose lung cancer screening with photon-counting CT: a feasibility study.

To evaluate the feasibility of using a whole-body photon-counting detector (PCD) CT scanner for low-dose lung cancer screening compared to a conventional energy integrating detector (EID) system. Radiation dose-matched EID and PCD scans of the COPDGene 2 phantom were acquired at different radiation dose levels (CTDI: 3.0, 1.

Dual-Energy Computed Tomography of the Knee, Ankle, and Foot: Noninvasive Diagnosis of Gout and Quantification of Monosodium Urate in Tendons and Ligaments.

Gout is a true crystal deposition arthropathy caused by the precipitation of monosodium urate into joints and periarticular soft tissues. It is the most common inflammatory arthropathy in men and women of older age with a male-to-female ratio of 3 to 8:1. The disease may progress from asymptomatic hyperuricemia through symptomatic acute gout attacks with asymptomatic periods into chronic symptomatic tophaceous gout.

Abdominal Imaging with Contrast-enhanced Photon-counting CT: First Human Experience.

Purpose: To evaluate the performance of a prototype photon-counting detector (PCD) computed tomography (CT) system for abdominal CT in humans and to compare the results with a conventional energy-integrating detector (EID).

Materials And Methods: The study was HIPAA-compliant and institutional review board-approved with informed consent. Fifteen asymptomatic volunteers (seven men; mean age, 58.

Quantitative Dual-Energy Computed Tomography Supports a Vascular Etiology of Smoking-induced Inflammatory Lung Disease.

Rationale: Endothelial dysfunction is of interest in relation to smoking-associated emphysema, a component of chronic obstructive pulmonary disease (COPD). We previously demonstrated that computed tomography (CT)-derived pulmonary blood flow (PBF) heterogeneity is greater in smokers with normal pulmonary function tests (PFTs) but who have visual evidence of centriacinar emphysema (CAE) on CT.

Objectives: We introduced dual-energy CT (DECT) perfused blood volume (PBV) as a PBF surrogate to evaluate whether the CAE-associated increased PBF heterogeneity is reversible with sildenafil.

Comparison of breathing gated CT images generated using a 5DCT technique and a commercial clinical protocol in a porcine model.

Purpose: To demonstrate that a "5DCT" technique which utilizes fast helical acquisition yields the same respiratory-gated images as a commercial technique for regular, mechanically produced breathing cycles.

Methods: Respiratory-gated images of an anesthetized, mechanically ventilated pig were generated using a Siemens low-pitch helical protocol and 5DCT for a range of breathing rates and amplitudes and with standard and low dose imaging protocols. 5DCT reconstructions were independently evaluated by measuring the distances between tissue positions predicted by a 5D motion model and those measured using deformable registration, as well by reconstructing the originally acquired scans.

Task-based image quality evaluation of iterative reconstruction methods for low dose CT using computer simulations.

Iterative reconstruction (IR) methods for x-ray CT is a promising approach to improve image quality or reduce radiation dose to patients. The goal of this work was to use task based image quality measures and the channelized Hotelling observer (CHO) to evaluate both analytic and IR methods for clinical x-ray CT applications. We performed realistic computer simulations at five radiation dose levels, from a clinical reference low dose D0 to 25% D0.

Very low-dose (0.15 mGy) chest CT protocols using the COPDGene 2 test object and a third-generation dual-source CT scanner with corresponding third-generation iterative reconstruction software.

Objectives: The purpose of this study was to evaluate the impact of ultralow radiation dose single-energy computed tomographic (CT) acquisitions with Sn prefiltration and third-generation iterative reconstruction on density-based quantitative measures of growing interest in phenotyping pulmonary disease.

Materials And Methods: The effects of both decreasing dose and different body habitus on the accuracy of the mean CT attenuation measurements and the level of image noise (SD) were evaluated using the COPDGene 2 test object, containing 8 different materials of interest ranging from air to acrylic and including various density foams. A third-generation dual-source multidetector CT scanner (Siemens SOMATOM FORCE; Siemens Healthcare AG, Erlangen, Germany) running advanced modeled iterative reconstruction (ADMIRE) software (Siemens Healthcare AG) was used.

Early airway structural changes in cystic fibrosis pigs as a determinant of particle distribution and deposition.

The pathogenesis of cystic fibrosis (CF) airway disease is not well understood. A porcine CF model was recently generated, and these animals develop lung disease similar to humans with CF. At birth, before infection and inflammation, CF pigs have airways that are irregularly shaped and have a reduced caliber compared to non-CF pigs.

Scatter correction associated with dedicated dual-source CT hardware improves accuracy of lung air measures.

Rationale And Objectives: Accurate assessment of air density used to quantitatively characterize amount and distribution of emphysema in chronic obstructive pulmonary disease (COPD) subjects has remained challenging. Hounsfield units (HU) within tracheal air can be considerably less negative than -1000 HU. This study has sought to characterize the effects of improved scatter correction used in dual-source pulmonary computed tomography (CT).

Quantification of ventilation distribution in regional lung injury by electrical impedance tomography and xenon computed tomography.

Validation studies of electrical impedance tomography (EIT) based assessment of regional ventilation under pathological conditions are required to prove that EIT can reliably quantify heterogeneous ventilation distribution with sufficient accuracy. The objective of our study was to validate EIT measurements of regional ventilation through a comparison with xenon-multidetector-row computed tomography (XeCT) in an animal model of sub-lobar lung injury. Nine anesthetized mechanically ventilated supine pigs were examined before and after the induction of lung injury in two adjacent sub-lobar segments of the right lung by saline lavage or endotoxin instillation.

Effect of lung inflation level on hyperpolarized 3He apparent diffusion coefficient measurements in never-smokers.

Purpose: To evaluate the effects of lung volume differences on apparent diffusion coefficient (ADC) measurements on a regional basis, with breath holds at volumes adjusted for differences in lung size across individuals according to the subject's vital capacity (VC).

Materials And Methods: This study was approved by the local institutional review board and was compliant with HIPAA. Informed consent was obtained from all subjects.

Optimization of dual-energy xenon-computed tomography for quantitative assessment of regional pulmonary ventilation.

Objective: Dual-energy x-ray computed tomography (DECT) offers visualization of the airways and quantitation of regional pulmonary ventilation using a single breath of inhaled xenon gas. In this study, we sought to optimize scanning protocols for DECT xenon gas ventilation imaging of the airways and lung parenchyma and to characterize the quantitative nature of the developed protocols through a series of test-object and animal studies.

Materials And Methods: The Institutional Animal Care and Use Committee approved all animal studies reported here.

MDCT-based quantification of porcine pulmonary arterial morphometry and self-similarity of arterial branching geometry.

The pig is frequently used as an experimental model for studies of the pulmonary circulation, yet the branching and dimensional geometry of the porcine pulmonary vasculature remains poorly defined. The purposes of this study are to improve the geometric definition of the porcine pulmonary arteries and to determine whether the arterial tree exhibits self-similarity in its branching geometry. Five animals were imaged using thin slice spiral computed tomography in the prone posture during airway inflation pressure at 25 cmH2O.

An in-vivo computed tomography approach for quantifying porcine pulmonary arterial morphometry.

The objective of this study was to develop an in vivo CT imaging-based approach for pulmonary arterial morphometry measurement, and to improve the geometrical basis for studies of the porcine vasculature. The luminal diameter and distance from the inlet of left and right pulmonary arteries, and pulmonary arteries within the lungs of two porcine subjects were measured at inflation pressure of 25 cmH(2)O. The results suggest that the porcine pulmonary arteries have geometric self-similarity, and that this approach will have utility for systematically quantifying pulmonary arterial vessel dimensions in vivo in a larger group of animals.

Pulmonary perfused blood volume with dual-energy CT as surrogate for pulmonary perfusion assessed with dynamic multidetector CT.

Purpose: To compare measurements of regional pulmonary perfused blood volume (PBV) and pulmonary blood flow (PBF) obtained with computed tomography (CT) in two pig models.

Materials And Methods: The institutional animal care and use committee approved all animal studies. CT-derived PBF and PBV were determined in four anesthetized, mechanically ventilated, supine swine by using two methods for creating pulmonary parenchymal perfusion heterogeneity.

Comparison of image registration based measures of regional lung ventilation from dynamic spiral CT with Xe-CT.

Purpose: Regional lung volume change as a function of lung inflation serves as an index of parenchymal and airway status as well as an index of regional ventilation and can be used to detect pathologic changes over time. In this paper, the authors propose a new regional measure of lung mechanics-the specific air volume change by corrected Jacobian. The authors compare this new measure, along with two existing registration based measures of lung ventilation, to a regional ventilation measurement derived from xenon-CT (Xe-CT) imaging.

Systems for lung volume standardization during static and dynamic MDCT-based quantitative assessment of pulmonary structure and function.

Rationale And Objectives: Multidetector-row computed tomography (MDCT) has emerged as a tool for quantitative assessment of parenchymal destruction, air trapping (density metrics), and airway remodeling (metrics relating airway wall and lumen geometry) in chronic obstructive pulmonary disease (COPD) and asthma. Critical to the accuracy and interpretability of these MDCT-derived metrics is the assurance that the lungs are scanned during a breathhold at a standardized volume.

Materials And Methods: A computer monitored turbine-based flow meter system was developed to control patient breathholds and facilitate static imaging at fixed percentages of the vital capacity.

Regional aeration and perfusion distribution in a sheep model of endotoxemic acute lung injury characterized by functional computed tomography imaging.

Objectives: Sepsis-related lung injury is the most common and morbid form of acute lung injury. The objective of this study was to develop an ovine model of septic acute lung injury and characterize its pathophysiology regarding its recruitability and changes in regional aeration and perfusion distributions at injury and during injury evolution.

Design: Experimental animal study.

Total and regional lung volume changes during high-frequency oscillatory ventilation (HFOV) of the normal lung.

The effect of high-frequency oscillatory ventilation (HFOV) settings on the distribution of lung volume (V(L)) with changes in mean airway pressure (Paw), frequency (f(R)) and tidal volume (V(T)) remains controversial. We used computer tomographic (CT) imaging to quantify the distribution of V(L) during HFOV compared to static continuous positive airway pressure (CPAP). In anesthetized, supine canines, CT imaging of the entire lung was performed during CPAP and HFOV at Paw of 5, 12.