State of the art: iterative CT reconstruction techniques

Owing to recent advances in computing power, iterative reconstruction (IR) algorithms have become a clinically viable option in computed tomographic (CT) imaging. Substantial evidence is accumulating about the advantages of IR algorithms over established analytical methods, such as filtered back projection. IR improves image quality through cyclic image processing. Although all available solutions share the common mechanism of artifact reduction and/or potential for radiation dose savings, chiefly due to image noise suppression, the magnitude of these effects depends on the specific IR algorithm. In the first section of this contribution, the technical bases of IR are briefly reviewed and the currently available algorithms released by the major CT manufacturers are described. In the second part, the current status of their clinical implementation is surveyed. Regardless of the applied IR algorithm, the available evidence attests to the substantial potential of IR algorithms for overcoming traditional limitations in CT imaging

Functional Imaging: CT and MRI

SYNOPSIS: Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled MDCT allow for quantification of presence and distribution of parenchymal and airway pathology, Xenon gas can be employed to assess regional ventilation of the lungs and rapid bolus injections of iodinated contrast agent can provide quantitative measure of regional parenchymal perfusion. Advances in magnetic resonance imaging (MRI) of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized helium imaging, which can allow imaging of pulmonary ventilation and .measurement of the size of emphysematous spaces

Cardiac computed tomography: indications, applications, limitations, and training requirements: Report of a Writing Group deployed by the Working Group Nuclear Cardiology and Cardiac CT of the European Society of Cardiology and the European Council of Nuclear Cardiology

As a consequence of improved technology, there is growing clinical interest in the use of multi-detector row computed tomography (MDCT) for non-invasive coronary angiography. Indeed, the accuracy of MDCT to detect or exclude coronary artery stenoses has been high in many published studies. This report of a Writing Group deployed by the Working Group Nuclear Cardiology and Cardiac CT (WG 5) of the European Society of Cardiology and the European Council of Nuclear Cardiology summarizes the present state of cardiac CT technology, as well as the currently available data concerning its accuracy and applicability in certain clinical situations. Besides coronary CT angiography, the use of CT for the assessment of cardiac morphology and function, evaluation of perfusion and viability, and analysis of heart valves is discussed. In addition, recommendations for clinical applications of cardiac CT imaging are given and limitations of the technique are describe

Semiautomated Skeletonization of the Pulmonary Arterial Tree in Micro-CT Images

We present a simple and robust approach that utilizes planar images at different angular rotations combined with unfiltered back-projection to locate the central axes of the pulmonary arterial tree. Three-dimensional points are selected interactively by the user. The computer calculates a sub- volume unfiltered back-projection orthogonal to the vector connecting the two points and centered on the first point. Because more x-rays are absorbed at the thickest portion of the vessel, in the unfiltered back-projection, the darkest pixel is assumed to be the center of the vessel. The computer replaces this point with the newly computer-calculated point. A second back-projection is calculated around the original point orthogonal to a vector connecting the newly-calculated first point and user-determined second point. The darkest pixel within the reconstruction is determined. The computer then replaces the second point with the XYZ coordinates of the darkest pixel within this second reconstruction. Following a vector based on a moving average of previously determined 3- dimensional points along the vessel\u27s axis, the computer continues this skeletonization process until stopped by the user. The computer estimates the vessel diameter along the set of previously determined points using a method similar to the full width-half max algorithm. On all subsequent vessels, the process works the same way except that at each point, distances between the current point and all previously determined points along different vessels are determined. If the difference is less than the previously estimated diameter, the vessels are assumed to branch. This user/computer interaction continues until the vascular tree has been skeletonized

Untersuchung der klinischen Bedeutung einer computerassistierten Diagnosesoftware zur Quantifizierung von Lungengerüstprozessen mittels Multislice-Spiral-CT und Korrelation mit der Lungenfunktionsdiagnostik

Die sozioökonomische Bedeutung der Erkrankungen des Lungengerüsts hat in den letzten Jahren enorm zugenommen. Deshalb ist die zuverlässige Detektion sowohl des Lungenemphysems als auch der Lungenfibrose anzustreben. Steigende Datenmengen durch den Gebrauch von Multislice- Scannern und fehlende objektive Quantifizierungsmethoden machen die zusätzliche computergestützte Auswertung der CT-Daten im klinischen Alltag wünschenswert. Das Ziel dieser Arbeit bestand in der Evaluation der klinischen Anwendbarkeit einer Software zur Quantifizierung von Erkrankungen des Lungengerüsts anhand von MS-CT-Datensätzen im Vergleich zur Lungenfunktionsdiagnostik. In die retrospektive Studie gingen die Daten von insgesamt 100 Patienten ein, die sich sowohl einer Bodyplethysmographie als auch einer MS-CT des Thorax unterzogen haben. Das Gesamtkollektiv wurde in Subgruppen mit Atemwegsobstruktion und restriktiver Ventilationsstörung geteilt. Mit Hilfe des CAD-Systems PULMO 3D der Firma MeVis wurden die CT-Aufnahmen aller Patienten voll automatisiert analysiert. Die von der Software ausgegebenen Parameter wurden mit den per Lungenfunktionsuntersuchung bestimmten Volumina korreliert. Dabei zeigte sich, dass es machbar ist, diagnoserelevante Parameter der Lungenfunktion durch CAD-Anwendung aus CT-Daten zu extrahieren, wobei die Bestimmung dynamischer Parameter wie der Einsekundenkapazität (FEV1) derzeit nicht ausreichend gelingt. Die Unterscheidung zwischen Obstruktion und Restriktion ist mittels quantitativer Analyse grundsätzlich möglich. Des weiteren ergaben sich signifikante Unterschiede der CAD-basiert ermittelten Parameter im Hinblick auf die Stadien der peripheren Obstruktion und der Restriktion, so dass eine Abhängigkeit vom Erkrankungsausmaß angenommen werden kann. Allerdings demonstrieren die Ergebnisse dieser Studie auch, dass die reproduzierbare Schweregradeinteilung erst mit der Definition von Referenz- bzw. Normwerten ermöglicht wird

Focal Spot, Fall/Winter 2002/2003

https://digitalcommons.wustl.edu/focal_spot_archives/1092/thumbnail.jp

Statement on imaging and pulmonary hypertension from the Pulmonary Vascular Research Institute (PVRI)

Pulmonary hypertension (PH) is highly heterogeneous and despite treatment advances it remains a life-shortening condition. There have been significant advances in imaging technologies, but despite evidence of their potential clinical utility, practice remains variable, dependent in part on imaging availability and expertise. This statement summarizes current and emerging imaging modalities and their potential role in the diagnosis and assessment of suspected PH. It also includes a review of commonly encountered clinical and radiological scenarios, and imaging and modeling-based biomarkers. An expert panel was formed including clinicians, radiologists, imaging scientists, and computational modelers. Section editors generated a series of summary statements based on a review of the literature and professional experience and, following consensus review, a diagnostic algorithm and 55 statements were agreed. The diagnostic algorithm and summary statements emphasize the key role and added value of imaging in the diagnosis and assessment of PH and highlight areas requiring further research