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Nuclear norm-regularized SENSE reconstruction
- Magnetic Reson Imaging
, 2012
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All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Robot-Guided Open-Loop Insertion of Skew-Line Needle Arrangements for High Dose Rate Brachytherapy
"... Abstract — We present a study in human-centered automation that has potential to reduce patient side effects from high dose rate brachytherapy (HDR-BT). To efficiently deliver radiation to the prostate while minimizing trauma to sensitive structures such as the penile bulb, we modified the Acubot-RN ..."
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Abstract — We present a study in human-centered automation that has potential to reduce patient side effects from high dose rate brachytherapy (HDR-BT). To efficiently deliver radiation to the prostate while minimizing trauma to sensitive structures such as the penile bulb, we modified the Acubot-RND 7-axis robot to guide insertion of diamond-tip needles into desired skew-line geometric arrangements. We extend and integrate two algorithms: Needle Planning with Integer Programming (NPIP) and Inverse Planning with Integer Programming (IPIP) to compute skew-line needle and dose plans. We performed three physical experiments with anatomically-correct phantom models to study performance: two with the robot and one control experiment with an expert human physician (co-author Hsu) without the robot. All were able to achieve needle arrangements that meet the RTOG-0321 clinical dose objectives with zero trauma to the penile bulb. We analyze systematic and random errors in needle placement; total RMS error for the robot system operating without feedback ranged from 2.6 mm to 4.3 mm, which is comparable to the RMS error of 2.7 mm obtained in an earlier study for PPI-BT treatment using a robot with 3D ultrasound feedback. Note to Practitioners Brachytherapy treats cancer by delivering radioactive sources proximal to cancer sites via needles. Current methods use standardized fixed mechanical templates that force needles into parallel arrangements that may prevent needles from reaching prostate volumes blocked by the pubic arch and often require needles to puncture sensitive organs. Skew-line (non-parallel) arrangements of needles can reach targets under the pubic arch and avoid sensitive organs. However these arrangements cannot be achieved with standard templates, motivating the use of automation. We present a human-centered automation system that integrates state-of-the-
Article Calibrationless Parallel Magnetic Resonance Imaging: A Joint Sparsity Model
, 2013
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The AGILE library for image reconstruction in biomedical sciences using graphics card hardware acceleration
, 2012
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Magnetic Resonance in Medicine 63:1456–1462 (2010) Nonlinear Inverse Reconstruction for Real-Time MRI of the Human Heart Using Undersampled Radial FLASH
"... Apreviously proposednonlinear inverse reconstruction for auto-calibrated parallel imaging simultaneously estimates coil sen-sitivities and image content. This work exploits this property for real-time MRI, where coil sensitivities need to be dynami-cally adapted to the conditions generated by moving ..."
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Apreviously proposednonlinear inverse reconstruction for auto-calibrated parallel imaging simultaneously estimates coil sen-sitivities and image content. This work exploits this property for real-time MRI, where coil sensitivities need to be dynami-cally adapted to the conditions generated by moving objects. The development comprises (i) an extension of the nonlin-ear inverse algorithm to non-Cartesian k-space encodings, (ii) its implementation on a graphical processing unit to reduce reconstruction times, and (iii) the use of a convolution-based iteration, which considerably simplifies the graphical process-ing unit implementation compared to a gridding technique. The method is validated for real-time MRI of the human heart at 3 T using radio frequency-spoiled radial FLASH (pulse repetition time/echo time = 2.0/1.3 ms, flip angle 8◦). The results demon-strate artifact-free reconstructions from only 65–85 spokes,
REVIEW Open Access The Role of Cardiovascular Magnetic Resonance in Pediatric Congenital Heart Disease
"... Cardiovascular magnetic resonance (CMR) has expanded its role in the diagnosis and management of congenital heart disease (CHD) and acquired heart disease in pediatric patients. Ongoing technological advancements in both data acquisition and data presentation have enabled CMR to be integrated into c ..."
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Cardiovascular magnetic resonance (CMR) has expanded its role in the diagnosis and management of congenital heart disease (CHD) and acquired heart disease in pediatric patients. Ongoing technological advancements in both data acquisition and data presentation have enabled CMR to be integrated into clinical practice with increasing understanding of the advantages and limitations of the technique by pediatric cardiologists and congenital heart surgeons. Importantly, the combination of exquisite 3D anatomy with physiological data enables CMR to provide a unique perspective for the management of many patients with CHD. Imaging small children with CHD is challenging, and in this article we will review the technical adjustments, imaging protocols and application of CMR in the pediatric population. 1.
Research Article On the Physiology of Normal Swallowing as Revealed by Magnetic Resonance Imaging in Real Time
"... Copyright © 2014 Arno Olthoff et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The aim of this study was to assess the physiolo ..."
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Copyright © 2014 Arno Olthoff et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The aim of this study was to assess the physiology of normal swallowing using recent advances in real-time magnetic resonance imaging (MRI). Therefore ten young healthy subjects underwent real-time MRI and flexible endoscopic evaluations of swallowing (FEES) with thickened pineapple juice as oral contrast bolus. MRI movies were recorded in sagittal, coronal, and axial orientations during successive swallows at about 25 frames per second. Intermeasurement variation was analyzed and comparisons between real-time MRI and FEES were performed. Twelve distinct swallowing events could be quantified by real-time MRI (start time, end time, and duration). These included five valve functions: oro-velar opening, velo-pharyngeal closure, glottal closure, epiglottic retroflexion, and esophageal opening; three bolus transports: oro-velar transit, pharyngeal delay, pharyngeal transit; and four additional events: laryngeal ascent, laryngeal descent, vallecular, and piriform sinus filling and pharyngeal constriction. Repetitive measurements confirmed the general reliability of the MRI method with only two significant differences for the start times of the velo-pharyngeal closure (
Real-time MRI with Nonlinear Inverse Reconstruction
"... In parallel MRI, the acquisition of data from multiple receive coils allows for the undersampling of k-space to accelerate the measurement. For autocalibrated parallel imaging, the recent development of a nonlinear reconstruction algorithm [1] provides a better estimation of the required coil sens ..."
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In parallel MRI, the acquisition of data from multiple receive coils allows for the undersampling of k-space to accelerate the measurement. For autocalibrated parallel imaging, the recent development of a nonlinear reconstruction algorithm [1] provides a better estimation of the required coil sensitivities than conventional (linear) approaches, which in turn improves the desired image. This is accomplished by solving the signal equation simultaneously for both the coil sensitivities and the image content using the iteratively regularized Gauss-Newton method [1]. The algorithm has originally been formulated for Cartesian sampling, but can also be applied to non-Cartesian trajectories [2,3]. In fact, the combination of the nonlinear inverse reconstruction with acquisitions based on undersampled radial FLASH [4] has many advantageous properties for real-time imaging: It allows for continuous imaging, is highly robust to motion and undersampling, and automatically adapts to changing coil sensitivities for a moving object. After describing the basic reconstruction algorithm and its extension to non-Cartesian sampling, this presentation will discuss the improvements for dynamic imaging, which exploit temporal constraints and filters. These changes further enhance the temporal fidelity and quality of the reconstructions, as
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"... Technical notesReal-time cardiovascular magnetic resonance at high temporal resolution: radial FLASH with nonlinear inverse reconstruction ..."
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Technical notesReal-time cardiovascular magnetic resonance at high temporal resolution: radial FLASH with nonlinear inverse reconstruction
