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

Quantitative multi-modality imaging analysis of a fully bioresorbable stent: a head-to-head comparison between QCA, IVUS and OCT

The bioresorbable vascular stent (BVS) is totally translucent and radiolucent, leading to challenges when using conventional invasive imaging modalities. Agreement between quantitative coronary angiography (QCA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) in the BVS is unknown. Forty five patients enrolled in the ABSORB cohort B1 study underwent coronary angiography, IVUS and OCT immediately post BVS implantation, and at 6 months. OCT estimated stent length accurately compared to nominal length (95% CI of the difference: −0.19; 0.37 and −0.15; 0.47 mm2 for baseline and 6 months, respectively), whereas QCA incurred consistent underestimation of the same magnitude at both time points (Pearson correlation = 0.806). IVUS yielded low accuracy (95% CI of the difference: 0.77; 3.74 and −1.15; 3.27 mm2 for baseline and 6 months, respectively), with several outliers and random variability test–retest. Minimal lumen area (MLA) decreased substantially between baseline and 6 months on QCA and OCT and only minimally on IVUS (95% CI: 0.11; 0.42). Agreement between the different imaging modalities is poor: worst agreement Videodensitometry-IVUS post-implantation (ICCa 0.289); best agreement IVUS-OCT at baseline (ICCa 0.767). All pairs deviated significantly from linearity (P < 0.01). Passing-Bablok non-parametric orthogonal regression showed constant and proportional bias between IVUS and OCT. OCT is the most accurate technique for measuring stent length, whilst QCA incurs systematic underestimation (foreshortening) and solid state IVUS incurs random error. Volumetric calculations using solid state IVUS are therefore not reliable. There is poor agreement for MLA estimation between all the imaging modalities studied, including IVUS-OCT, hence their values are not interchangeable

Hypertrophic non-obstructive apical cardiomyopathy : a case presentation and review of the literature

CITATION: Przybojewski, J. Z. & Blake, R. S. 1984. Hypertrophic non-obstructive apical cardiomyopathy : a case presentation and review of the literature. South African Medical Journal, 66:492-498.The original publication is available at http://www.samj.org.zaA 20-year-old coloured man gave a history of atypical chest pain, palpitations after strenuous exercise and a single episode of post-exertional presyncope. The diagnosis of hypertrophic non-obstructive apical cardiomyopathy (HNOAC) was established by means of electrocardiography, echocardiography (both M-mode and two-dimensional) and left ventricular cine angiography. This variant of hypertrophic cardiomyopathy is most unusual and has been encountered most frequently in Japan, although a few cases have been diagnosed in the USA. The present case is the second reported from the Republic of South Africa. Important aspects of HNOAC are reviewed.Publisher’s versio

Doenças coronarianas e o auxílio da técnica de tomografia computorizada para o seu diagnóstico

As doenças cardiovasculares são uma das principais causas mundiais de morte, inclusive no Brasil, ocasionando aproximadamente trezentas mil mortes anualmente. Entre estas, as doenças nas artérias coronarianas ocupam um papel importante na taxa de mortalidade, não por suas alterações primárias (artereoesclerose, ateroesclerose), mas pelas complicações geradas por sua obstrução (isquemia, arritmias graves e infarto do miocárdio). Essas patologias quando rastreadas e comparadas com os fatores de riscos podem ser minimizadas e diminuir o risco de óbito. Dentre os exames de diagnóstico há a cineangiografia, um método invasivo que e considerado o padrão ouro para essas alterações. Entretanto estudos mostram que a técnica de tomografia computadorizada, com a modernização dos tomógrafos, diminuindo drasticamente a emissão de radiação ionizante, vem sendo utilizada como uma alternativa no seu rastreio (escore de cálcio) e diagnóstico (angiotomografia do miocárdio). Este trabalho consiste em uma revisão bibliográfica narrativa com o objetivo de analisar as doenças coronarianas e a técnica da tomografia computadorizada para o seu diagnóstico.https://repositorio.uniceub.br/jspui/retrieve/37190/21504023.pd

Comprehensive 4D velocity mapping of the heart and great vessels by cardiovascular magnetic resonance

<p>Abstract</p> <p>Background</p> <p>Phase contrast cardiovascular magnetic resonance (CMR) is able to measure all three directional components of the velocities of blood flow relative to the three spatial dimensions and the time course of the heart cycle. In this article, methods used for the acquisition, visualization, and quantification of such datasets are reviewed and illustrated.</p> <p>Methods</p> <p>Currently, the acquisition of 3D cine (4D) phase contrast velocity data, synchronized relative to both cardiac and respiratory movements takes about ten minutes or more, even when using parallel imaging and optimized pulse sequence design. The large resulting datasets need appropriate post processing for the visualization of multidirectional flow, for example as vector fields, pathlines or streamlines, or for retrospective volumetric quantification.</p> <p>Applications</p> <p>Multidirectional velocity acquisitions have provided 3D visualization of large scale flow features of the healthy heart and great vessels, and have shown altered patterns of flow in abnormal chambers and vessels. Clinically relevant examples include retrograde streams in atheromatous descending aortas as potential thrombo-embolic pathways in patients with cryptogenic stroke and marked variations of flow visualized in common aortic pathologies. Compared to standard clinical tools, 4D velocity mapping offers the potential for retrospective quantification of flow and other hemodynamic parameters.</p> <p>Conclusions</p> <p>Multidirectional, 3D cine velocity acquisitions are contributing to the understanding of normal and pathologically altered blood flow features. Although more rapid and user-friendly strategies for acquisition and analysis may be needed before 4D velocity acquisitions come to be adopted in routine clinical CMR, their capacity to measure multidirectional flows throughout a study volume has contributed novel insights into cardiovascular fluid dynamics in health and disease.</p