Advanced Post-processing Techniques Research Articles

Ground-glass opacity: High-resolution computed tomography and 64-multi-slice computed tomography findings comparison

Objective Comparative evaluation of ground-glass opacity using conventional high-resolution computed tomography technique and volumetric computed tomography by 64-row multi-slice scanner, verifying advantage of volumetric acquisition and post-processing technique allowed by 64-row CT scanner. Methods Thirty-four patients, in which was assessed ground-glass opacity pattern by previous high-resolution computed tomography during a clinical-radiological follow-up for their lung disease, were studied by means of 64-row multi-slice computed tomography. Comparative evaluation of image quality was done by both CT modalities. Results It was reported good inter-observer agreement ( k value 0.78–0.90) in detection of ground-glass opacity with high-resolution computed tomography technique and volumetric Computed Tomography acquisition with moderate increasing of intra-observer agreement ( k value 0.46) using volumetric computed tomography than high-resolution computed tomography. Conclusions In our experience, volumetric computed tomography with 64-row scanner shows good accuracy in detection of ground-glass opacity, providing a better spatial and temporal resolution and advanced post-processing technique than high-resolution computed tomography.

Renal Stone Assessment with Dual-Energy Multidetector CT and Advanced Postprocessing Techniques: Improved Characterization of Renal Stone Composition—Pilot Study

To prospectively evaluate the capability of noninvasive, simultaneous dual-energy (DE) multidetector computed tomography (CT) to improve characterization of human renal calculi in an anthropomorphic DE renal phantom by introducing advanced postprocessing techniques, with ex vivo renal stone spectroscopy as the reference standard. Fifty renal calculi were assessed: Thirty stones were of pure crystalline composition (uric acid, cystine, struvite, calcium oxalate, calcium phosphate, brushite), and 20 were of polycrystalline composition. DE CT was performed with a 64-detector CT unit. A postprocessing algorithm (DECT(Slope)) was proposed as a pixel-by-pixel approach to generate Digital Imaging and Communications in Medicine dataset gray-scale-encoding ratios of relative differences in attenuation values of low- and high-energy DE CT. Graphic analysis, in which clusters of equal composition were identified, was performed by sorting attenuation values of color composition-encoded calculi in an ascending sequence. Multivariate general linear model analysis was used to determine level of significance to differentiate composition on native and postprocessed DE CT images. Graphic analysis of native DE CT images was used to identify clusters for uric acid (453-629 HU for low-energy CT, 443-615 HU for high-energy CT), cystine (725-832 HU for low-energy CT, 513-747 HU for high-energy CT), and struvite (1337-1530 HU for low-energy CT, 1007-1100 HU for high-energy CT) stones; high-energy clusters showed attenuation value overlap. Polycrystalline calcium oxalate and calcium phosphate calculi were found throughout the entire spectrum, and dense brushite had attenuation values of more than 1500 HU for low-energy CT and more than 1100 HU for high-energy CT. The DE CT algorithm was used to generate specific identifiers for uric acid (77-80 U(Slope), one outlier), cystine (70-71 U(Slope)), struvite (56-60 U(Slope)), calcium oxalate and calcium phosphate (17-59 U(Slope)), and brushite (4-15 U(Slope)) stones. Statistical analysis showed that all compositions were identified unambiguously with the DECT(Slope) algorithm. DE multidetector CT with advanced postprocessing techniques improves characterization of renal stone composition beyond that achieved with single-energy multidetector CT acquisitions with basic attenuation assessment.

Blood pool inversion volume-rendering technique for visualization of the aortic valve

This brief review focuses on use of an advanced postprocessing volume-rendering technique for cardiac computed tomographic angiography (CTA) called blood pool inversion (BPI). In particular, we focus on the application of BPI in visualization of the aortic valve. Practical tips and tricks about aortic valve imaging with cardiac CTA are given. Topics include optimization of patient preparation and image acquisition; strengths and limitations of standard postprocessing techniques such as multiplanar reconstruction, maximal intensity projection, and minimum intensity projection; and use of advanced volume rendering with BPI for assessment of aortic valve disease.

Closure to “Turbulence Measurements with Acoustic Doppler Velocimeters” by Carlos M. García, Mariano I. Cantero, Yarko Niño, and Marcelo H. García

The contribution was a timely notice that acoustic Doppler velocimeters have intrinsic weaknesses and that their signal outputs are not always true turbulence measurements. Herein it is demonstrated that, in steady open channel flows, the sampling record must be larger than 5,000 samples to yield minimum errors on first and second statistical moments of the velocity components. Significantly longer records (more than 50,000 samples) are required for accurate determination of higher statistical moments (e.g. skewness, kurtosis), Reynolds stresses and triple correlations. Further ADV signal outputs are adversely affected by the proximity of solid boundaries, particularly when the sampling volume is located less than 30 to 45 mm from the wall. Recent field observations in a small estuary showed also that ADV records may be affected by various disturbances including wildlife and man-made interferences. Comparative analyses of long duration, high-frequency data sets highlighted the needs for advanced post-processing techniques. It is hoped that the authors' contribution and the present discussion will stress enough the needs to educate and adequately train technicians, engineers, scientists and researchers deploying ADVs in the field, including portable ADV systems.

Advanced post-processing and correlation analyses in high-velocity air–water flows

The interest in air-water flows has not diminished in recent years, but it is accompanied by frequent citations of early, sometimes outdated articles. A basic issue is the inadequate, incomplete interpretation of air-water flow instrumentation by hydraulic engineers and researchers. This article comments on high-velocity air-water flow measurements by means of intrusive phase detection probes. This article focus on the bubbly flow structure of high-velocity air-water flow based upon measurements by means of intrusive phase detection probes. It is shown that some advanced post-processing techniques may yields expanded information on the air-water turbulent flow properties and bubbly flow structures. The outcomes demonstrate simple techniques in high-velocity air-water flow analysis.

From a Product Model to Visualization: Simulation of Indoor Flows with Lattice‐Boltzmann Methods

Abstract: After a short discussion of different types of models being involved in the process of numerical simulation in civil engineering, we focus on the analysis of indoor air flow through complex geometries. All models are derived from a product data model based on Industry Foundation Classes. Concepts of the Lattice‐Boltzmann method are described, being used as the numerical kernel of our simulation system. We take advantage of spacetrees as a central data structure for all geometry related objects. Finally, we describe some advanced postprocessing and visualization techniques allowing to efficiently analyze huge amounts of simulation data.

Multidetector-row helical CT and advanced postprocessing techniques for the evaluation of pancreatic neoplasms.

An important feature of multidetector-row helical computed tomography (CT) is the increased speed of scanning that permits routine use of very thin collimation and acquisition of near isometric imaging data of the abdomen within the time span of a single breath-hold. The parallel escalation in the capabilities of workstations makes feasible the practical use of advanced postprocessing techniques to create high quality volumetric imaging. This article highlights the unique contributions of multidetector-row CT and advanced postprocessing techniques to the evaluation of the pancreas and peripancreatic vascular structures and their value in the diagnosis and staging of pancreatic neoplasms.

A multilayer perceptron neural model for the differentiation of laplacian 3-D finite-element solutions

An MLP neural model is presented in order to evaluate accurately derivatives of rough finite-element numerical solutions to three-dimensional Laplacian electromagnetic problems. The adopted neural approach overcomes the limitations inherent to advanced postprocessing techniques based on Poisson integrals because it is applicable to domains of arbitrary shape. The training of the neural network is performed off-line by employing a modular class of harmonic polynomial functions. Accuracy can be predetermined at the user's convenience by suitably selecting the order of the polynomial functions in the off-line training. The tests performed show that accurate results are achieved with a negligible online computational effort. A further advantage of this neural model is its easy implementation in existing postprocessing modules.

Advanced 3-D imaging for the evaluation of pancreatic cancer with multidetector CT.

Pancreatic cancer remains the fourth leading cause of cancer-related death. Surgery is the only option for cure. Multidetector computed tomography (CT) and advanced postprocessing techniques, can provide solutions for difficult problems in diagnosing and staging disease, and can aid radiologists in communicating findings to surgeons and oncologists. Multiplanar reformats can provide additional information on involvement of the portal vein, hepatic artery, and common bile duct. Maximum intensity projection (MIP) images and volume rendered images can aid in identification of important vascular variants. MIP images can show the relationship of tumor to the pancreatic duct or biliary tree. Curved reformatted images can show the relationship of tumor to the pancreatic duct or vascular structures.

Radiologic anatomy of the paranasal air sinuses

Over the last decade, significant strides have been made in the imaging-guided management of sinonasal inflammation. We are now able to achieve an enhanced level of understanding of the complex functional and surgical anatomy of this region. This facilitates meaningful communication with the surgeons who consult with us. Sectional imaging using both CT and MR is applied well to sinonasal imaging, but anatomic CT landmarks are emphasized in this article with its connection to minimally invasive sinus surgery. Our ongoing research efforts target dynamic functional anatomy with advanced postprocessing techniques.

Intracranial aneurysms: detection and characterization with MR angiography with use of an advanced postprocessing technique in a blinded-reader study.

To assess magnetic resonance (MR) angiography for the detection and characterization of angiographically proved intracranial aneurysms by using an advanced method of postprocessing, in a blinded-reader study. One hundred fifty-eight vessels were examined with catheter angiography and three-dimensional time-of-flight MR angiography in 44 patients with 63 aneurysms and 15 patients with no aneurysm at catheter angiography. Postprocessing was performed off-line with an advanced multifeature-extraction, ray-tracing algorithm. MR angiograms were interpreted independently by three neuroradiologists blinded to the catheter angiographic results for presence, location, size, and morphology of the aneurysm. Proof of diagnosis was consensus reading of catheter angiograms. Mean sensitivity for detection of aneurysms was 75% (range, 70%-79%). As a screening tool (ie, detection of at least one aneurysm necessitating catheter angiography), mean sensitivity was 91% for all aneurysms and 95% for aneurysms larger than 3 mm. This method was not adequate for detection of lobulation or size of aneurysm. MR angiography with an advanced method of postprocessing can result in highly sensitive, specific studies for the diagnosis of intracranial aneurysms that are of sufficient size to be considered for surgical treatment, but it is inadequate for characterization of aneurysms.