Fourier Velocity Encoded MRI: Acceleration and Velocity Map Estimation

Fourier velocity encoding (FVE) is an alternative to phase contrast imaging (PC). FVE provides considerably higher SNR than PC, due to its higher dimensionality and larger voxel sizes. Furthermore, FVE is robust to partial voluming, as it resolves the velocity distribution within each voxel. FVE data are usually acquired with low spatial resolution, due to scan-time restrictions associated with its higher dimensionality. FVE is capable of providing the velocity distribution associated with a large voxel, but does not directly provides a velocity map. Knowing the velocity distribution on a voxel is important for accurate diagnosis of stenosis in vessels on the scale of spatial resolution. Velocity maps, however, are useful for visualizing the actual blood flow through a vessel and can be used in different studies and diagnosis. In this context, this chapter deals with two aspects of the FVE MRI technique: acceleration and estimation of velocity map. First, are introduced six different acceleration techniques that can be applied to FVE acquisition. Methods such as variable-density sampling and compressive sampling. Then, is proposed a novel method to estimate velocity maps with high spatial resolution from low-resolution FVE data. Finally, it can be concluded that FVE datasets can be acquired in time scale comparable to PC, it contains more velocity information, since it resolves a velocity distribution within a voxel, and also provides an accurate estimation of the velocity map

Compressive sensing method for improved reconstruction of gradient-sparse magnetic resonance images

We propose a compressive sensing method for reconstructing gradient-sparse magnetic resonance (MR) images based on the pre-filtering of the input signals in the k-space. A set of filtered versions of the image is reconstructed using the available k-space samples, and a final reconstruction stage generates the desired image from the filtered versions. Our experiments, conducted over real MR images and angiograms, show that the proposed method improves the reconstruction over the total-variation minimization, in terms of signal-to-noise ratio and computation time. The proposed method is particularly appropriate for computing MR angiograms, which are typically sparse under the finite-differences operation

Embodiments, visualizations, and immersion with enactive affective systems

Our proposal in Bioart and Biomedical Engineering for a ective esthetics focuses on the expanded sensorium and investigates problems regarding enactive systems. These systems enhance the sensorial experiences and amplify kinesthesia by adding the sensations that are formed in response to the physical world, which aesthetically constitutes the principle of synaesthesia. In this paper, we also present enactive systems inside the CAVE, con guring compelling experiences in data landscapes and human a ective narratives. The interaction occurs through the acquisition, data visualization and analysis of several synchronized physiological signals, to which the landscapes respond and provide immediate feedback, according to the detected participants' actions and the intertwined responses of the environment. The signals we use to analyze the human states include the electrocardiography (ECG) signal, the respiratory ow, the galvanic skin response (GSR) signal, plantar pressures, the pulse signal and others. Each signal is collected by using a speci cally designed dedicated electronic board, with reduced dimensions, so it does not interfere with normal movements, according to the principles of transparent technologies. Also, the electronic boards are implemented in a modular approach, so they are independent, and can be used in many di erent desired combinations, and at the same time provide synchronization between the collected data

Effects of Biofeedback in Preventing Urinary Incontinence and Erectile Dysfunction after Radical Prostatectomy

In this study, we present a biofeedback method for the strengthening of perineal muscles during the preoperative procedures for radical prostatectomy, and we evaluate this technique as a prevention measure against complications such as urinary incontinence (UI) and erectile dysfunction (ED), which affect prostatectomy patients after surgery. In the experimental protocol, the patients performed specific exercises with the help of a device that provided the patient with visual biofeedback, based on a plot of the anal pressure. For the experimental protocol, we selected 20 male patients, with an average age of 64.0 years, and submitted them to ten therapeutic sessions each. A control group consisting of 32 men with an average age of 66.3 years, who were treated with the same surgical procedure but not with the preoperative procedures, also took part in the experiment. To evaluate UI and ED after the surgery in both control and experimental groups, we used two validated questionnaires—to assess UI, we used the King’s Health Questionnaire (KHQ) and, for ED, we used the International Index of Erectile Function (IIEF-5) Questionnaire. We compared the variables associated with UI and ED after the surgery for the control and experimental groups. The occurrence of UI after radical prostatectomy in the control group (100% of the patients) was higher than that for the experimental group (5% of the patients), with p < 0.0001. Likewise, the occurrence of erectile dysfunction after prostatectomy in the control group (48.6% of the patients) was higher than that for the experimental group (5% of the patients), with p < 0.0001. The number of nocturia events also decreased as a consequence of the intervention (p < 0.0001), as did the number of disposable underwear units for urinary incontinence (p < 0.0001). Furthermore, we compared, only for the experimental group, the anal pressure before the biofeedback intervention and after the surgery, and we verified that the anal pressure after surgery was significantly higher (p < 0.0001). The results strongly suggest that the preoperative biofeedback procedure was effective in decreasing urinary incontinence and erectile dysfunction after radical prostatectomy. As future work, we intend to extend this analysis for larger samples and considering a broader age range