Desired Plane Research Articles

Micro‐computed tomography: an alternative method for shark ageing

Micro-computed tomography (microCT) produced 3D reconstructions of shark Carcharhinus brevipinna vertebrae that could be virtually sectioned along any desired plane, and upon which growth bands were readily visible. When compared to manual sectioning, it proved to be a valid and repeatable means of ageing and offers several distinct advantages over other ageing methods.

A Novel Algorithm to Minimize the Excitation of Undesirable Oscillations-State Space

A new state-space type stabilizer to minimize low frequency oscillation is proposed. The proposed Power System Stabilizer (PSS) design not only damps the oscillations by moving the Eigen-values to desired left hand plane locations but additionally reduces the excitation of the mode itself through optimization of the left eigenvector of the poorly damped electro-mechanical mode. The stabilizer is implemented as a State-Space (SS) type controller which is optimized using a constrained optimization procedure. Two possible inputs, speed and electrical power are considered as candidate inputs to the stabilizers. The state-space design is also compared with one based on traditional lead-lag compensation. The SS type stabilizer with electrical power input is shown to perform better compared to any other type of PSS by minimizing low frequency oscillations.

Observer Design for Needle Steering Using Task-Induced Symmetry and Reduction

AbstractReduction induced either by the inherent dynamics of a system or control task at hand is often advantageous for analysis and control of the system. In the current work we consider state estimation for flexible, tip-steerable needle insertions. Specifically, we design observers that exploit the symmetry induced by the task of controlling the needle to a desired plane. These needles curve inside the tissue as they are inserted into it and have been modeled as a six degree of freedom nonholonomic system. Several planning and control algorithms have been proposed to automate needle insertions so as to improve their accuracy. Central to these algorithms is the estimation of the needle states (position and orientation of the needle tip) from only the needle-tip position measurements; needle-tip orientation cannot be directly measured since the needle shaft is very thin. We first show that the needle steering system is an observable system and then illustrate how the planar task decomposes the configuration space into a reduced space and a fiber space. Finally, we design an observer on the reduced space and an embedded-space observer on the fiber space.

Real-Time Digital Holographic Microscopy for Phase Contrast 3D Imaging of Dynamic Phenomena

Digital holography is a very effective tool for three- dimensional imaging of objects, since it yields the phase information directly without the need for additional optics. Another advantage is that of numerical focusing, allowing one to focus on to any desired plane. It has been used for microscopy with high effectiveness. One of the important features of digital holographic microscopy (DHM) is that it can be used for phase contrast imaging of otherwise transparent objects. This aspect of DHM is utilized here to study the dynamics of phase objects. Angular spectrum propagation (ASP) approach to scalar diffraction theory is used for numerical reconstruction of holograms.

Optical section imaging of the tilted planes by illumination-angle-scanning digital interference holography

A new method of optical imaging that can generate the section images of arbitrarily tilted planes has been developed from illumination-angle-scanning digital interference holography. A set of complex object fields are reconstructed from the holograms captured as the illumination angle is varied with uniform intervals. After the complex fields are modified with phase ramps that match the tilt (relative to the hologram plane) of a desired observation plane, the image of the object sliced along the tilted plane is obtained from their superposition. The axial resolution of a system employing this method is measured with a step height standard, and it is applied to the tomographic inspection of a microelectromechanical system.

Clinical Primetime for Cardiovascular Magnetic Resonance

Cardiovascular magnetic resonance (CMR) is a rapidly emerging noninvasive imaging technique providing highresolution images of the heart in any desired plane without the use of ionizing radiation. CMR provides potentially important information with respect to cardiac morphology, function, contractile reserve, myocardial perfusion, and tissue morphology including infarct detection. The potential gains from CMR studies are high, and it carries very few serious risks. Consequently, in many tertiary centers, CMR is increasingly used but detailed information about safety and outcome from a large number of scanned patients has been missing. Thus, there is a paucity of data as to how CMR performs in a “real world” clinical setting. The European Cardiovascular Magnetic Resonance Registry will seek to answer such questions with respect to a number of clinical protocols, and the German pilot phase sought to establish the current general referral pattern and to provide for a detailed estimate for how often side effects and clinically useful diagnostic outcome is seen.

Cardiovascular magnetic resonance imaging for detection of myocardial viability in chronic ischemic left ventricular dysfunction

Chronic ischemic left ventricular dysfunction is present in number of clinical syndromes in which myocardial revascularization results in an improvement of left ventricular function, patients' functional class, and their survival. Coronary arteriography is of limited value in diagnosis of viability. Noninvasive testing, traditionally nuclear imaging, stress echocardiography and (stress) electrocardiography have been the clinical mainstays for assessing myocardial viability as well as to detect myocardial ischemia. However, cardiovascular magnetic resonance is a rapidly emerging noninvasive imaging technique, providing high-resolution images of the heart in any desired plane and without radiation. Rather than a single technique, cardiovascular magnetic resonance consists of several techniques that can be performed separately or in various combinations during a patient examination. Whereas, no single cardiovascular magnetic resonance technique has a perfect, or near perfect, sensitivity and specificity, therefore, a combination of various cardiovascular magnetic resonance techniques are needed for the assessment of myocardial viability. The aim of this review article is to summarize our current understanding of the concept of myocardial viability, to discuss the clinical value of cardiovascular magnetic resonance (in particular the different cardiovascular magnetic resonance techniques to assess viability) for the evaluation of patients with coronary artery disease and chronic left ventricular dysfunction and to present the current place of cardiovascular magnetic resonance among other techniques for the assessment of viable myocardium.

Three-Dimensional Fluid Attenuated Inversion Recovery Imaging With Isotropic Resolution and Nonselective Adiabatic Inversion Provides Improved Three-Dimensional Visualization and Cerebrospinal Fluid Suppression Compared to Two-Dimensional Flair at 3 Tesla

In this investigation, we compare two-dimensional (2D) fluid-attenuated inversion recovery (FLAIR) imaging of the brain to an isotropic three-dimensional (3D) FLAIR technique that uses a modulated refocusing flip angle echo train and parallel imaging with 2D acceleration. Two-dimensional and 3D FLAIR sequences were obtained in 16 patients. All examinations were performed on a 3 Tesla (T) magnetic resonance (MR) system. Flow artifacts within the subarachnoid space and ventricles were scored using a 4-point scale. For 2D and 3D FLAIR, the signal-to-noise ratios and contrast-to-noise ratios were calculated. Compared to 2D FLAIR, the 3D FLAIR images were less degraded by flow artifacts in the subarachnoid space and ventricle (P < 0.03) based on the qualitative imaging scores. Signal-to-noise ratios and contrast-to-noise ratios were higher for 3D FLAIR (P < 0.02) for all variables when compared with 2D FLAIR sequence. The acquisition time for whole brain isotropic fast spin echo 3D FLAIR can be dramatically reduced by using an extended echo train with flip angle modulation and parallel imaging. The adiabatic, nonselective inversion pulse encompasses the entire volume and provides uniform suppression of the cerebrospinal fluid signal eliminating cerebrospinal fluid pulsation artifacts. Other advantages include reformatting in any desired plane, volume measurements, displays of surface anatomy, and coregistration.

Ischaemic and non-ischaemic cardiomyopathies — cardiac MRI appearances with delayed enhancement

Over the past few years, cardiovascular magnetic resonance (CMR) imaging has rapidly developed and is now a robust clinical tool capable of providing high-resolution images of the heart in any desired plane. Delayed contrast-enhanced CMR (DE-CMR) can be used for non-invasive tissue characterization, with differing patterns of hyperenhancement displayed by ischaemic and non-ischaemic cardiomyopathies. This review explains the theory behind delayed hyperenhancement, and demonstrates the potential of DE-CMR in the diagnosis of a wide range of different cardiac disease states.

Transitional cell carcinoma in a herniated vesical diverticulum

Carcinoma in vesical diverticula is a rare clinical entity and rarer still is the herniation of the vesical diverticulum into the scrotal sac. Carcinoma arising within a vesical diverticulum often represents a diagnostic as well as a therapeutic challenge, with overall poor outcome despite all available forms of treatment. Multidetector CT helps in the diagnosis and detailed evaluation of carcinoma arising from the vesical diverticulum by allowing excellent reconstructions in any desired plane. We report here a case of transitional cell carcinoma arising in a herniated vesical diverticulum with hepatic metastasis.

Comparison of Accuracy of Aortic Valve Area Assessment in Aortic Stenosis by Real Time Three‐Dimensional Echocardiography in Biplane Mode versus Two‐Dimensional Transthoracic and Transesophageal Echocardiography

Our aim was to validate the clinical feasibility of assessment of the area of the aortic valve orifice (AVA) by real time three-dimensional echocardiography (RT3DE) in biplane mode by planimetry and to compare it with the echo-Doppler methods more commonly used to evaluate valvular aortic stenosis (AS).RT3DE in biplane mode is a novel technique that allows operators to visualize the aortic valve orifice anatomy in any desired plane orientation. Its usefulness and accuracy have not previously been established. Using this technique, we studied a series of patients with AS and compared the results with those obtained by two-dimensional transesophageal echocardiography (TEE) planimetry and two-dimensional transthoracic echocardiography using the continuity equation (TTE-CE). RT3DE planimetries in biplane mode were measured by two independent observers. Bland-Altman analysis was used to compare these two methods.Forty-one patients with AS were enrolled in the study (15 women, 26 men, mean age 73.5 +/- 8.2 years). RT3DE planimetry was feasible in 92.7%. Average AVA determined by TTE-CE was 0.76 +/- 0.20 cm, by TEE planimetry 0.73 +/- 0.1 cm, and by RT3DE planimetry 0.76 +/- 0.20 cm(2). The average differences in AVA were-0.001 +/- 0.254 cm(2) and 0.03 +/- 0.155 cm(2) (RT3DE/TEE). The correlation coefficient for AVA (RT3DE/TTE-CE) was 0.82 and for AVA (RT3DE/TEE) it was 0.94, P < 0.0001. No significant intra- and interobserver variability was observed. In conclusion, RT3DE in biplane mode provides a feasible and reproducible method for measuring the area of the aortic valve orifice in aortic stenosis.

Clinical utility of magnetic resonance angiography (MRA) in the diagnosis and treatment of Takayasu’s arteritis

Dear Editor, The first case of Takayasu’s arteritis (TA) was described in 1908 by Dr. Mikito Takayasu [1] at the Annual Meeting of the Japan Ophthalmology Society. Dr. Takayasu described a peculiar “wreathlike” appearance of blood vessels in the back of the eye (retina). Two Japanese colleagues at the same meeting reported similar eye findings in patients whose wrist pulses were absent. It is now known that TA is a large-vessel vasculitis of unknown etiology that has a predilection for the aorta and its primary branches Figs. 1 and 2. TA has traditionally been divided into an early, “prepulseless” systemic phase and a late occlusive phase. In the early systemic phase, diagnosis is difficult and symptoms are usually nonspecific and constitutional, including fever, myalgias, weight loss, and arthralgias. In the occlusive phase, ischemic symptoms dominate, including angina, claudication, syncope, and visual impairment. Late-phase TA may be further subclassified as classic pulseless disease (type 1), a mixed type (type 2), an atypical coarctation type (type 3), and a dilated type (type 4). The clinical presentation of TA and the results of laboratory tests at the onset of the disease are typically nonspecific, which may lead to delayed diagnosis and most of the patients present with the late-phase disease. Accurate diagnosis virtually always depends on imaging studies; nevertheless, angiography is an invasive method that carries well-known risks of complications resulting from the procedure itself, such as hematoma, arteriovenous fistula, pseudoaneurysm, and vessel thrombosis. The reported overall prevalence of a major vascular complication is 0.02–9% [2]. Magnetic resonance angiography (MRA) advantages include the lack of the need for ionizing radiation and iodinated contrast material; therefore, MRA is ideal for serial evaluation of patients with TA who are undergoing treatment. Furthermore, MRA provides the ability to view vessels in any desired plane, and techniques like cine magnetic resonance imaging (MRI) can detect cardiovascular functional and hemodynamic changes, such as aortic regurgitation, in patients with TA. As with the CT scan, MRI is useful for early diagnosis because of its ability to evaluate wall thickness rather than just the luminal narrowing. In addition, MRA provides detailed information about the location, extent, and degree of vascular involvement. It also provides detailed information about the extent of stenotic lesions, the patency of collateral vessels, and it also seems useful as a follow-up modality to assess the response to treatment [3]. Given the fact that in clinical practice, some patients with TA show normal Erythrocyte sedimentation rate (ESR) at their initial evaluation, and this may give false impression that they Clin Rheumatol (2007) 26:1393–1395 DOI 10.1007/s10067-007-0577-2

Imaging and quantifying valvular heart disease using magnetic resonance techniques

Echocardiography remains the cornerstone of noninvasive valvular heart disease evaluation. There are instances where MRI can be of use. Aside from the obvious advantage where limited acoustic windows are present, cardiac magnetic resonance (CMR) allows for imaging in any desired plane, and advantage can be taken of the ability to align with any regurgitant or stenotic flow jet. The high spatial resolution and contrast allow for accurate detail of valvular anatomy, but it must be remembered that the images represent a composite of eight to 12 heart cycles. For visualizing multiple valvular abnormalities simultaneously, cardiac MRI has a distinct advantage. Finally, a CMR valvular examination can be combined with accurate assessments of left and right ventricular function, myocardial stress perfusion imaging, and detailed viability determinations in a single examination. This provides a comprehensive presurgical evaluation of cardiac physiology.

Delayed enhancement cardiovascular magnetic resonance assessment of non-ischaemic cardiomyopathies

Non-ischaemic cardiomyopathies (NICMs) are chronic, progressive myocardial diseases with distinct patterns of morphological, functional, and electrophysiological changes. In the setting of cardiomyopathy (CM), determining the exact aetiology is important because the aetiology is directly related to treatment and patient survival. Determining the exact aetiology, however, can be difficult using currently available imaging techniques, such as echocardiography, radionuclide imaging or X-ray coronary angiography, since overlap of features between CMs may be encountered. Cardiovascular magnetic resonance (CMR) imaging has recently emerged as a new non-invasive imaging modality capable of providing high-resolution images of the heart in any desired plane. Delayed contrast enhanced CMR (DE-CMR) can be used for non-invasive tissue characterization and may hold promise in differentiating ischaemic from NICMs, as the typical pattern of hyperenhancement can be classified as 'ischaemic-type' or 'non-ischaemic type' on the basis of pathophysiology of ischaemia. This article reviews the potential of DE-CMR to distinguish between ischaemic and NICM as well as to differentiate non-ischaemic aetiologies. Rather than simply describing various hyperenhancement patterns that may occur in different disease states, our goal will be (i) to provide an overall imaging approach for the diagnosis of CM and (ii) to demonstrate how this approach is based on the underlying relationships between contrast enhancement and myocardial pathophysiology.

Symmetric phase only filtering: a new paradigm for DPIV data processing

The standard approach in digital particle image velocimetry (DPIV) data processing is to use fast Fourier transforms to obtain the cross-correlation of two single exposure subregions, where the location of the cross-correlation peak is representative of the most probable particle displacement across the subregion. This standard DPIV processing technique is analogous to matched spatial filtering, a technique commonly used in optical correlators to perform the cross-correlation operation. Phase only filtering is a well-known variation of matched spatial filtering, which when used to process DPIV image data yields correlation peaks which are narrower and up to an order of magnitude larger than those obtained using traditional DPIV processing. In addition to possessing desirable correlation plane features, phase only filters also provide superior performance in the presence of dc noise in the correlation subregion. When DPIV image subregions contaminated with surface flare light or high background noise levels are processed using phase only filters, the correlation peak pertaining only to the particle displacement is readily detected above any signal stemming from the dc objects. Tedious image masking or background image subtraction is not required. Both theoretical and experimental analyses of the signal-to-noise ratio performance of the filter functions are presented. In addition, a new symmetric phase only filtering (SPOF) technique, which is a variation on the traditional phase only filtering technique, is described and demonstrated. The SPOF technique exceeds the performance of the traditionally accepted phase only filtering techniques and is easily implemented in standard DPIV FFT-based correlation processing with no significant computational performance penalty. The SPOF-based optical correlation processing approach is presented as a new paradigm for more robust cross-correlation processing of low signal-to-noise ratio DPIV image data.

Synthesis of linkages with four points of accuracy using Maple-V

A graphical and computational based method for synthesis of linkages with four-point of accuracy using the Maple-V software is presented. In our problem an arbitrary moving link of the mechanism should be located in four different attitudinal and translational positions with respect to another moving link. To design of such a mechanism the graphical based method is used but to prevent the lack of accuracy due to the graphical errors the method is implemented by computer graphics with using a mathematical symbolic software namely Maple-V. After definition of four relative positions of two moving links, all poles and image- poles are determined. Selecting an opposite pole quadrilateral, center point curve and circle point curves are obtained and drawn. By using a few commands in the Maple-V, these two curves can be achieved with the desirable precision and in the desirable plane. A sample problem is solved using the above mentioned method. In the example a six-bar linkage for independent type suspension mechanism of a vehicle is designed with four points of accuracy such that it maintains the camber angle of wheel when it moves over a bump. The method can be easily implemented for motion generation problems such as design of four points of the six-bar as well as Watt’s and Stephenson’s family mechanisms and can be applied not only in the professional designs but also for educational purposes.

Real-time three-dimensional echocardiography for rheumatic mitral valve stenosis evaluation: An accurate and novel approach

ObjectivesOur aim was to assess which echo-Doppler method has the best agreement with the mitral valve area (MVA) invasively evaluated by the Gorlin′s formula. We also evaluated the feasibility and reproducibility of real-time three-dimensional echocardiography (RT3D) for the estimation of MVA and the Wilkins score in patients with rheumatic mitral stenosis (RMVS). BackgroundReal-time three-dimensional echocardiography is a novel technique that allows us to visualize the mitral valvular anatomy in any desired plane orientation. The usefulness and accuracy of this technique for evaluating RMVS has not been established. MethodsWe studied a series of consecutive patients with RMVS from two tertiary care hospitals. Mitral valvular area was determined by conventional echo-Doppler methods and by RT3D, and their results were compared with those obtained invasively. Real-time three-dimensional echocardiography planimetry and mitral score were measured by two independent observers and then repeated by one of them. ResultsEighty patients with RMVS comprised our study group (76 women; 50.6 ± 13.9 years). Compared with all other echo-Doppler methods, RT3D had the best agreement with the invasively determined MVA (average difference between both methods and limits of agreement: 0.08 cm2[−0.48 to 0.6]). Interobserver variability was as good for RT3D (intraclass correlation coefficient [ICC] = 0.90) as for pressure half-time (PHT) (ICC = 0.95). For PHT and RT3D, the intraobserver variability was similar (ICC 0.92 and 0.96, respectively). Real-time three-dimensional echocardiography valvular score evaluation showed a better interobserver agreement with RT3D than with 2D echocardiography. ConclusionsReal-time three-dimensional echocardiography is a feasible, accurate, and highly reproducible technique for assessing MVA in patients with RMVS. Real-time three-dimensional echocardiography has the best agreement with invasive methods.

Optimal plane changes using third-body forces.

The fuel optimality of third-body driven plane changes (i.e., plane changes performed by using third-body forces) over one-impulse transfers is investigated numerically and analytically. In particular, the range of third-body driven plane changes that are realizable is shown to be restricted and one impulse must be used in the uncovered regions. However, when third-body driven plane changes are realizable, it is shown that they are always optimal above a certain critical value (about 40 degrees ) that depends on the initial condition. Contour plots of optimal DeltaV values to perform a desired plane changes are given.

Gadopentetate dimeglumine-enhanced three-dimensional MR-angiography: dosing, safety, and efficacy.

Noninvasiveness, inherent three-dimensionality allowing reformations in any desired plane, and safe contrast agents, coupled with high diagnostic accuracy have driven the rise in popularity of contrast-enhanced MR angiography (CE-MRA) within the medical community. Reflecting its dominant market share as a paramagnetic contrast agent, gadopentetate dimeglumine (Gd-DTPA) has been used for the majority of clinically-performed MRA exams. Over the period January 1994 to February 2002, a total of 172 original studies describing the use of gadolinium-enhanced MRA in more than three human subjects were identified. Of these, 117 described the use of Gd-DTPA as the contrast agent for MRA. A total of 4046 subjects who received Gd-DTPA for MRA are described in these studies. Analysis of these data demonstrate Gd-DTPA to be a safe contrast agent for MRA when applied in a dose ranging from 0.1 to 0.3 mmol/kg of bodyweight. The documented clinical results show Gd-DTPA to be efficacious in the assessment of the arterial system. The effectiveness of Gd-DTPA-enhanced MRA extends beyond the detection, localization, and characterization of arterial disease, and encompasses choice and planning of appropriate therapy, as well as evaluation of therapeutic effectiveness.

Multislice CT: technical principles and future trends

Multislice scanning has substantially improved the performance of CT scanners, and thus the relation between scan duration, available scan length, and spatial resolution along the patient axis (z-axis). Near-isotropic imaging of whole organ systems is already possible with 4-slice scanners, but only with 8- to 16-slice scanners can the scan duration be shortened as well. Reconstructing overlapping thin-section data ("secondary raw data set") provides the basis for image reconstruction in any desired plane. By using thick multiplanar reformation (MPR) techniques, image quality can be improved while keeping patient dose low. Using unfavorable scanning parameters, exposure dose can be substantially increased compared with single-slice scanning, but thick MPR and individual-dose modulation techniques can provide the basis for dose reduction. Low-kVp scanning, in particular, is useful in children and slim adults and is an excellent technique to improve image contrast in CT angiographic studies. Short spiral scans should be avoided with multislice CT since overranging (extra rotations at the beginning and end of the scan, used for data interpolation) can substantially increase patient dose. Future trends include the introduction of thinner detector rows, wider detector arrays, faster tube rotation, and area detectors than can also be used for fluoroscopy. Noise-reduction techniques and individual dose modulation will gain importance with higher isotropic resolution. Functional and perfusion imaging, as well as advanced image processing and computer-aided diagnosis programs, will add to the possibilities of the next generation of multislice CT scanners.