Rationale: Comorbidities contribute to disease severity and mortality in patients with chronic obstructive pulmonary disease (COPD). Comorbidities have been studied individually and were mostly based on self-reports. The coexistence of objectively identified comorbidities and the role of low-grade systemic inflammation in the pathophysiology of COPD remain to be elucidated.Objectives: To cluster 13 clinically important objectively identified comorbidities, and to characterize the comorbidity clusters in terms of clinical outcomes and systemic inflammation.Methods: A total of 213 patients with COPD (FEV1, 51 ± 17% predicted; men, 59%; age, 64 ± 7 yr) were included prospectively. Comorbidities were based on well-known cut-offs identified in the peer-reviewed English literature. Systemic inflammatory biomarkers were determined in all patients. Self-organizing maps were used to generate comorbidity clusters.Measurements and Main Results: A total of 97.7% of all patients had one or more comorbidities and 53.5%...

https://www.heritage.azm.nl/afbeeldingen/pdfstore_mumcweb/Vanfleteren%20AJRCCM%202013.pdf

Clusters of Comorbidities Based on Validated Objective Measurements and Systemic Inflammation in Patients with Chronic Obstructive Pulmonary Disease

Morphological and functional parameters such as chamber size and function, aortic diameters and distensibility, flow and T1 and T2* relaxation time can be assessed and quantified by cardiovascular magnetic resonance (CMR). Knowledge of normal values for quantitative CMR is crucial to interpretation of results and to distinguish normal from disease. In this review, we present normal reference values for morphological and functional CMR parameters of the cardiovascular system based on the peer-reviewed literature and current CMR techniques and sequences.

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Normal values for cardiovascular magnetic resonance in adults and children

The role of vascular biomarkers for primary and secondary prevention. A position paper from the European Society of Cardiology Working Group on peripheral circulation: Endorsed by the Association for Research into Arterial Structure and Physiology (ARTERY) Society.

Medical image analysis

Cardiovascular magnetic resonance (CMR) tagging has been established as an essential technique for measuring regional myocardial function. It allows quantification of local intramyocardial motion measures, e.g. strain and strain rate. The invention of CMR tagging came in the late eighties, where the technique allowed for the first time for visualizing transmural myocardial movement without having to implant physical markers. This new idea opened the door for a series of developments and improvements that continue up to the present time. Different tagging techniques are currently available that are more extensive, improved, and sophisticated than they were twenty years ago. Each of these techniques has different versions for improved resolution, signal-to-noise ratio (SNR), scan time, anatomical coverage, three-dimensional capability, and image quality. The tagging techniques covered in this article can be broadly divided into two main categories: 1) Basic techniques, which include magnetization saturation, spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), and complementary SPAMM (CSPAMM); and 2) Advanced techniques, which include harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC). Although most of these techniques were developed by separate groups and evolved from different backgrounds, they are in fact closely related to each other, and they can be interpreted from more than one perspective. Some of these techniques even followed parallel paths of developments, as illustrated in the article. As each technique has its own advantages, some efforts have been made to combine different techniques together for improved image quality or composite information acquisition. In this review, different developments in pulse sequences and related image processing techniques are described along with the necessities that led to their invention, which makes this article easy to read and the covered techniques easy to follow. Major studies that applied CMR tagging for studying myocardial mechanics are also summarized. Finally, the current article includes a plethora of ideas and techniques with over 300 references that motivate the reader to think about the future of CMR tagging.

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Myocardial tagging by Cardiovascular Magnetic Resonance: evolution of techniques--pulse sequences, analysis algorithms, and applications

The new SinMod method extracts motion from magnetic resonance imaging (MRI)-tagged (MRIT) image sequences. Image intensity in the environment of each pixel is modeled as a moving sine wavefront. Displacement is estimated at subpixel accuracy. Performance is compared with the harmonic-phase analysis (HARP) method, which is currently the most common method used to detect motion in MRIT images. SinMod can handle line tags, as well as speckle patterns. In artificial images (tag distance six pixels), SinMod detects displacements accurately (error < pixels). Effects of noise are suppressed effectively. Sharp transitions in motion at the boundary of an object are smeared out over a width of 0.6 tag distance. For MRIT images of the heart, SinMod appears less sensitive to artifacts, especially later in the cardiac cycle when image quality deteriorates. For each pixel, the quality of the sine-wave model in describing local image intensity is quantified objectively. If local quality is low, artifacts are avoided by averaging motion over a larger environment. Summarizing, SinMod is just as fast as HARP, but it performs better with respect to accuracy of displacement detection, noise reduction, and avoidance of artifacts.

Mapping Displacement and Deformation of the Heart With Local Sine-Wave Modeling

Automatic recognition of the common carotid artery in longitudinal ultrasound B-mode scans

Transcutaneous ultrasound measurements of common carotid artery (CCA) diameter and intima-media thickness (IMT) give insight on arterial dynamics and anatomy, both correlating well with atherosclerosis and risk of cardiovascular disease. We propose a novel automatic algorithm to estimate CCA diameter and IMT in ultrasound (US) images, based on separate analysis of anterior and posterior CCA walls and able to distinguish internal (intima-intima) and external (adventitia-adventitia) diameter. The method combines off-line signal- and image-processing techniques to accommodate echo images acquired at a frame rate of 30 Hz and composed directly from RF data, circumventing digital video-grabbing. Segmentation consists of automatic CCA recognition, followed by adventitial delineation performed with a sustain-attack filter with exponentially decaying reference functions. Intimal delineation is then based on the multiscale anisotropic barycenter (MAB), which is an extension of a known delineation method involving the “first order absolute central moment” of the echo amplitude. An automatic measure of the quality of the US beam incidence for each wall is superimosed on the CCA contour overlays for visual feedback. Validation is carried out on 36 US CCA acquisitions from 12 healthy volunteers, as well as on synthetic US images. Results indicate good accuracy on synthetic US images (within 1.3% for diameter and 3% for IMT). The in vivo intra-recording beat-to-beat variations are on average lower than 50 μm for external diameter and IMT, and lower than 100 μm for internal diameter. A comparison with a commercial device (ART.LAB system) shows that the proposed algorithm performs better in terms of inter-recording precision. The beam incidence control significantly improves the repeatability of IMT estimates, and motivates sonographers actively to maintain a proper scan plane throughout the acquisition to minimize the incidence of confounding factors. The method is clinically viable, providing robust estimates of CCA internal and external diameter and IMT waveforms for both CCA walls, even at a low B-mode update rate of 30 Hz. (E-mail: peter.brands@esaote.nl )

Automatic Localization of Intimal and Adventitial Carotid Artery Layers with Noninvasive Ultrasound: A Novel Algorithm Providing Scan Quality Control

Noninvasive diameter assessment in the common carotid artery (CCA) by means of ultrasound is a useful technique for estimation of arterial mechanical and dynamic properties, clinical screening and treatment monitoring Before presentation on screen, ultrasound images are subjected to nonlinear processing, eg, logarithmic compression and noise-level thresholding, to improve visualization In addition, signal saturation may occur, either in the received radiofrequency (RF) signals or in their envelopes The objective of this study is to evaluate the effect of signal nonlinearities on CCA diameter measurements by means of noninvasive B-mode ultrasound, comparing the performance of two different edge detectors In 14 healthy subjects, three repeated ultrasonic acquisitions (6 s) without saturation were performed The acquired RF signals were subjected off-line to envelope detection, logarithmic compression and various degrees of saturation applied to the signals before or after envelope detection For the purpose of CCA diameter estimation, artery walls were automatically outlined frame by frame As automatic edge detectors, we considered the sustain attack filter (SAF), based on exponentially decaying reference functions, and a derivative approach (DER), relying on the positions of first derivative maxima Both methods are applied within a region-of-interest located on the CCA No regularization of the detected wall positions by means of pre- or postprocessing is presently applied to directly relate the outcome of the edge detectors to the applied nonlinear processing Diameter values assessed with SAF are unaffected by logarithmic compression because of the possibility to integrate the compression characteristic of the ultrasound system into the method The estimated diameters values obtained with DER instead show differences in the order of 10% because of compression Saturation affects DER more than SAF; DER exhibits larger intrarecording and intrasubject variations in the estimated diameter values Therefore, SAF gives more precise and robust CCA diameter estimates than DER, and is more suited for integration in algorithms meant for vascular ultrasound image segmentation This study demonstrates the relevant effects of nonlinearities such as saturation and logarithmic compression on the quality of noninvasive US CCA diameter measurements

Nonlinear Processing in B-Mode Ultrasound Affects Carotid Diameter Assessment

The left ventricle (LV) of mammals with Situs Solitus (SS, normal organ arrangement) displays hardly any interindividual variation in myofiber pattern and experimentally determined torsion. SS LV myofiber pattern has been suggested to result from adaptive myofiber reorientation, in turn leading to efficient pump and myofiber function. Limited data from the Situs Inversus Totalis (SIT, a complete mirror image of organ anatomy and position) LV demonstrated an essential different myofiber pattern, being normal at the apex but mirrored at the base. Considerable differences in torsion patterns in between human SIT LVs even suggest variation in myofiber pattern among SIT LVs themselves. We addressed whether different myofiber patterns in the SIT LV can be predicted by adaptive myofiber reorientation and whether they yield similar pump and myofiber function as in the SS LV. With a mathematical model of LV mechanics including shear induced myofiber reorientation, we predicted myofiber patterns of one SS and three different SIT LVs. Initial conditions for SIT were based on scarce information on the helix angle. The transverse angle was set to zero. During reorientation, a non-zero transverse angle developed, pump function increased, and myofiber function increased and became more homogeneous. Three continuous SIT structures emerged with a different location of transition between normal and mirrored myofiber orientation pattern. Predicted SIT torsion patterns matched experimentally determined ones. Pump and myofiber function in SIT and SS LVs are similar, despite essential differences in myocardial structure. SS and SIT LV structure and function may originate from same processes of adaptive myofiber reorientation.

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Alessandro C. Rossi

Papers

Mapping Displacement and Deformation of the Heart With Local Sine-Wave Modeling

Automatic recognition of the common carotid artery in longitudinal ultrasound B-mode scans

Automatic Localization of Intimal and Adventitial Carotid Artery Layers with Noninvasive Ultrasound: A Novel Algorithm Providing Scan Quality Control

Nonlinear Processing in B-Mode Ultrasound Affects Carotid Diameter Assessment

Why SIT Works: Normal Function Despite Typical Myofiber Pattern in Situs Inversus Totalis (SIT) Hearts Derived by Shear-induced Myofiber Reorientation