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21 results on '"Stara, Riccardo"'

6. IMPULSE: A scalable algorithm for design of minimum SAR parallel transmit RF pulses

Author

Pendse, Mihir, Stara, Riccardo, Khalighi, Mohammad Mehdi, and Rutt, Brian

Subjects
Risk, Phantoms, Imaging, Radio Waves, fungi, Brain, Reproducibility of Results, Models, Theoretical, Image Enhancement, Magnetic Resonance Imaging, Sensitivity and Specificity, Article, body regions, Image Interpretation, Computer-Assisted, Humans, Computer Simulation, skin and connective tissue diseases, Algorithms, Software
Abstract

PURPOSE: Managing local SAR in parallel transmission requires ensuring that the peak SAR over a large number of voxels (>10(5)) is below the regulatory limit. The safety risk to the patient depends on cumulative (not instantaneous) SAR thus making a joint design of all RF pulses in a sequence desirable. We propose the Iterative Minimization Procedure with Uncompressed Local SAR Estimate (IMPULSE), an efficient optimization formulation and algorithm that can handle uncompressed SAR matrices and optimize pulses for all slices jointly within a practical time frame. METHODS: IMPULSE optimizes parallel transmit pulses for small-tip-angle slice selective excitation to minimize a single cost function incorporating multiple quantities (local SAR, global SAR, and per-channel power) averaged over the entire multislice scan subject to a strict constraint on excitation accuracy. Pulses for an 8-channel 7T head coil were designed with IMPULSE and compared to pulses designed using generic optimization algorithms and VOPs to assess the computation time and SAR performance benefits. RESULTS: IMPULSE achieves lower SAR and shorter computation time compared to a VOP approach. Compared to the generic SQP algorithm, computation time is reduced by a factor of 5–6 by using IMPULSE. Using as many as 6 million local SAR terms, up to 120 slices can be designed jointly with IMPULSE within 45 seconds. CONCLUSIONS: IMPULSE can handle significantly larger number of SAR matrices and slices than conventional optimization algorithms, enabling the use of uncompressed or partially compressed SAR matrices to design pulses for a multislice scan in a practical time frame.

Published
2018

9. IMPULSE: A scalable algorithm for design of minimum specific absorption rate parallel transmit RF pulses.

Author

Pendse, Mihir, Stara, Riccardo, Mehdi Khalighi, Mohammad, and Rutt, Brian

Abstract

Purpose: Managing local specific absorption rate (SAR) in parallel transmission requires ensuring that the peak SAR over a large number of voxels (>105) is below the regulatory limit. The safety risk to the patient depends on cumulative (not instantaneous) SAR thus making a joint design of all RF pulses in a sequence desirable. We propose the Iterative Minimization Procedure with Uncompressed Local SAR Estimate (IMPULSE), an efficient optimization formulation and algorithm that can handle uncompressed SAR matrices and optimize pulses for all slices jointly within a practical time frame. Theory and Methods: IMPULSE optimizes parallel transmit pulses for small‐tip‐angle slice selective excitation to minimize a single cost function incorporating multiple quantities (local SAR, global SAR, and per‐channel power) averaged over the entire multislice scan subject to a strict constraint on excitation accuracy. Pulses for an 8‐channel 7T head coil were designed with IMPULSE and compared with pulses designed using generic optimization algorithms and VOPs to assess the computation time and SAR performance benefits. Results: IMPULSE achieves lower SAR and shorter computation time compared with a VOP approach. Compared with the generic sequential quadratic programming algorithm, computation time is reduced by a factor of 5‐6 by using IMPULSE. Using as many as 6 million local SAR terms, up to 120 slices can be designed jointly with IMPULSE within 45 s. Conclusions: IMPULSE can handle significantly larger number of SAR matrices and slices than conventional optimization algorithms, enabling the use of uncompressed or partially compressed SAR matrices to design pulses for a multislice scan in a practical time frame. [ABSTRACT FROM AUTHOR]

Published
2019
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10. A 7T double-tuned (¹H/³¹P) microstrip surface RF coil for the Imago7 MR Scanner

Author

Retico, Alessandra, Vitacolonna, Assunta, Galante, Angelo, Florio, Tiziana M., Cimini, Annamaria, Stara, Riccardo, Tiberi, Gianluigi, Tosetti, Michela, Fontana, Nunzia, Manara, Giuliano, Monorchio, Agostino, and Alecci, Marcello

Subjects
double-tuned, radio-frequency coil, 7T, Magnetic Resonance Imaging (MRI), Biomedical Engineering, Computer Science Applications1707 Computer Vision and Pattern Recognition, Magnetic Resonance Spectroscopy (MRS), microstrip
Published
2015

11. A 7T double-tuned (1H/31P) microstrip surface RF coil for the Imago7 MR scanner

Author

Retico, Alessandra, Vitacolonna, Assunta, Galante, Angelo, Florio, TIZIANA MARILENA, Cimini, Anna Maria, Stara, Riccardo, Tiberi, Gianluigi, Tosetti, Michela, Fontana, Nunzia, Manara, Giuliano, Monorchio, Agostino, and Alecci, Marcello

Subjects
double-tuned, radio-frequency coil, 7T, Magnetic Resonance Imaging (MRI), Biomedical Engineering, Computer Science Applications1707 Computer Vision and Pattern Recognition, Magnetic Resonance Spectroscopy (MRS), microstrip
Published
2015

14. A 7T double-tuned (1H/31P) microstrip surface RF coil for the IMAGO7 MR scanner

Author

Retico, Alessandra, primary, Vitacolonna, Assunta, additional, Galante, Angelo, additional, Florio, Tiziana M., additional, Cimini, Annamaria, additional, Stara, Riccardo, additional, Tiberi, Gianluigi, additional, Tosetti, Michela, additional, Fontana, Nunzia, additional, Manara, Giuliano, additional, Monorchio, Agostino, additional, and Alecci, Marcello, additional

Published
2015
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15. Non-invasive assessment of Neuromuscular Disorders by 7 tesla Magnetic Resonance Imaging and Spectroscopy: Dedicated radio-frequency coil development

Author

Retico, Alessandra, primary, Stara, Riccardo, additional, Fantacci, Maria Evelina, additional, Toncelli, Alessandra, additional, Galante, Angelo, additional, Florio, Tiziana M., additional, Alecci, Marcello, additional, Cosottini, Mirco, additional, Astrea, Guja, additional, Battini, Roberta, additional, Tiberi, Gianluigi, additional, Costagli, Mauro, additional, and Tosetti, Michela, additional

Published
2015
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16. Investigation of maximum local specific absorption rate in 7 T magnetic resonance with respect to load size by use of electromagnetic simulations

Author

Tiberi, Gianluigi, primary, Fontana, Nunzia, additional, Costagli, Mauro, additional, Stara, Riccardo, additional, Biagi, Laura, additional, Symms, Mark Roger, additional, Monorchio, Agostino, additional, Retico, Alessandra, additional, Cosottini, Mirco, additional, and Tosetti, Michela, additional

Published
2015
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19. VALIDATION OF NUMERICAL APPROACHES FOR ELECTROMAGNETIC CHARACTERIZATION OF MAGNETIC RESONANCE RADIOFREQUENCY COILS

Author

Stara, Riccardo, primary, Fontana, Nunzia, additional, Tiberi, Gianluigi, additional, Monorchio, Agostino, additional, Manara, Giuliano, additional, Alfonsetti, Maria, additional, Galante, Angelo, additional, Vitacolonna, Assunta, additional, Alecci, Marcello, additional, Retico, Alessandra, additional, and Tosetti, Michela, additional

Published
2013
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20. RF coil design for low and high field MRI: Numerical methods and measurements

Author

Stara, Riccardo, primary, Fontana, Nunzia, additional, Alecci, Marcello, additional, Alfonsetti, Maria, additional, Galante, Angelo, additional, Vitacolonna, Assunta, additional, Biagi, Laura, additional, Buonincontri, Guido, additional, Del Guerra, Alberto, additional, Tosetti, Michela, additional, Manara, Giuliano, additional, Monorchio, Agostino, additional, Tiberi, Gianluigi, additional, and Retico, Alessandra, additional

Published
2011
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