Magnetic resonance butterfly coils: Design and application for hyperpolarized C studies

Hyperpolarized ¹³C magnetic resonance spectroscopy in pig models enables cardiac metabolism assessment and provides a powerful tool for heart physiology studies, although the low molar concentration of derivate metabolites gives rise to technological limitations in terms of data quality. The design of dedicated coils capable of providing large field of view with high Signal-to-Noise Ratio (SNR) data is of fundamental importance.     

Real-time multimodal medical image processing: a dynamicvolume-rendering application

A system for medical image processing has been proposed, which allows multimodal dynamic three-dimensional (3-D) visualization interactively and in real time. The system has been conceived to support medical specialists in the diagnosis of moving organs, such as the heart during the cardiac cycle, allowing them to compare information on perfusion/contraction match as a basis for diagnosis of important cardiovascular diseases. The 3-D volume rendering algorithm runs on a SIMD machine because of the great amount of data to be manipulated by always using the same operations. One of the features of the algorithm is the possibility to change, interactively, image processing and visualization parameters at any step, and to perform simple and effective image manipulations. Performance studies have demonstrated a very high global efficiency in practical situations by using typical data-volume dimensions. The system has been tested in the medical environment, by using magnetic resonance (MR) and single-photon emission-computed tomographic (SPECT) images     

Efficiency evaluation of a C Magnetic Resonance birdcage coil: Theory and comparison of four methods

Radiofrequency coils in Magnetic Resonance systems are used to produce a homogeneous B₁ field for exciting the nuclei and to pick up the signals emitted by the nuclei with high signal-to-noise ratio. Accordingly, coil performance affects strongly the quality of the obtained data and images.     

OPERA: a novel method to reduce ghost and aliasing artifacts

Objective

A method for Orthogonal Phase Encoding Reduction of Artifact (OPERA) was developed and tested.

Materials and methods

Because the position of ghosts and aliasing artifacts is predictable along columns or rows, OPERA combines the intensity values of two images acquired using the same parameters, but with swapped phase-encoding directions, to correct the artifacts. Simulations and phantom experiments were conducted to define the efficacy, robustness, and reproducibility. Clinical validation was performed on a total of 1003 images by comparing the OPERA-corrected images and the corresponding image standard in terms of Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR). The method efficacy was also rated using a Likert-type scale response by two experienced independent radiologists using a single-blinded procedure.

Results

Simulations and phantom experiments demonstrated the robustness and effectiveness of OPERA in reducing artifacts strength. OPERA application did not significantly change the SNR [+?4.16%; inter-quartile range (IQR): 2.72–5.01%] and CNR (+?4.30%; IQR: 2.86–6.04%) values. The two radiologists observed a total of 893 original images with artifacts (89.03% of the total images), a reduction in the perceived artifacts of 82.0% and 83.9% (p?<?0.0001), and an improvement in the perceived SNR (82.8% and 88.5%; K?=?0.714) and perceived CNR (86.9–88.9%; K?=?0.722).

Discussion

The study demonstrated that OPERA reduces MR artifacts and improves the perceived image quality.

     

A model-based method for myocardium flow estimation

4. Conclusions Results of the present study show that accurate estimates of myocardial blood flow may be obtained using a spatially distributed model of residual curves of an intravascular indicator. In order to improve myocardial blood flow reliability in blood flow estimates, also in presence of background noise inT/I curves, a wavelet-based denoising technique was successfully applied to residue curves.     

Combining high-performance computing and networking for advanced3-D cardiac imaging

The paper deals with the integration of a powerful parallel computer based image analysis and visualization system for cardiology into a hospital information system. Further services are remote access to the hospital Web server through an Internet network. The visualization system includes dynamic three dimensional representation of two types of medical images (e.g., magnetic resonance and nuclear medicine) as well as two images in the same modality (e.g., basal versus stress images). A series of software tools for quantitative image analysis developed for supporting diagnosis of cardiac disease are also available, including automated image segmentation and quantitative time evaluation of left ventricular volumes and related indices during cardiac cycle, myocardial mass, and myocardial perfusion indices. The system has been tested both at a specialized cardiologic center and for remote consultation in diagnosis of cardiac disease by using anatomical and perfusion magnetic resonance images