Application of PINS radiofrequency pulses to reduce power deposition in RARE/turbo spin echo imaging of the human head

Norris, David G.; Boyacıoğlu, Rasim; Schulz, Jenni; Barth, Markus; Koopmans, Peter J.

doi:10.1002/mrm.24991

Cited by 43 publications

(54 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The original motivation of using PINS pulses instead of multiband pulses were the SAR limitations, which especially come into play at 3 T: the application of multiple 180° RF pulses easily exceeds the SAR limits, even with conventional single‐slice acquisitions. We demonstrated that the power deposition per slice is significantly lower with the proposed pulse scheme, enabling the use of such pulse schemes greater than 1.5 T. Such a scheme may enable using spin‐echo‐based T 2 mapping at ultrahigh fields (i.e., 7 T and beyond) …”

Section: Discussionmentioning

confidence: 97%

Fast model‐based T₂ mapping using SAR‐reduced simultaneous multislice excitation

Hilbert

Schulz

Marques

et al. 2019

Magnetic Resonance in Med

Self Cite

View full text Add to dashboard Cite

Purpose To obtain whole‐brain high‐resolution T2 maps in 2 minutes by combining simultaneous multislice excitation and low‐power PINS (power independent of number of slices) refocusing pulses with undersampling and a model‐based reconstruction. Methods A multi‐echo spin‐echo sequence was modified to acquire multiple slices simultaneously, ensuring low specific absorption rate requirements. In addition, the acquisition was undersampled to achieve further acceleration. Data were reconstructed by subsequently applying parallel imaging to separate signals from different slices, and a model‐based reconstruction to estimate quantitative T2 from the undersampled data. The signal model used is based on extended phase graph simulations that also account for nonideal slice profiles and B1 inhomogeneity. In vivo experiments with 3 healthy subjects were performed to compare accelerated T2 maps to fully sampled single‐slice acquisitions. The accuracy of the T2 values was assessed with phantom experiments by comparing the T2 values to single‐echo spin‐echo measurements. Results In vivo results showed that conventional multi‐echo spin‐echo, simultaneous multislice, and undersampling result in similar mean T2 values within regions of interest. However, combining simultaneous multislice and undersampling results in higher SDs (about 7 ms) in comparison to a conventional sequence (about 3 ms). The T2 values were reproducible between scan and rescan (SD < 1.2 ms) within subjects and were in similar ranges across subjects (SD < 4.5 ms). Conclusion The proposed method is a fast T2 mapping technique that enables whole‐brain acquisitions at 0.7‐mm in‐plane resolution, 3‐mm slice thickness, and low specific absorption rate in 2 minutes.

show abstract

Section: Discussionmentioning

confidence: 97%

Fast model‐based T₂ mapping using SAR‐reduced simultaneous multislice excitation

Hilbert

Schulz

Marques

et al. 2019

Magnetic Resonance in Med

Self Cite

View full text Add to dashboard Cite

show abstract

“…With respect to Parseval's theorem, PINS can be seen as a special case of VERSE in which an infinite power in k‐space (corresponding to an infinite number of slices) is mapped to a finite power in the time domain by the stratagem of turning off the gradients during the application of the RF pulse. An interesting consequence of this is that PINS pulses have an exceedingly low magnetisation transfer contrast effect, as the RF pulses are always transmitted on‐resonance . Periodic excitation has been used before to create cardiac tagging patterns and dates as far back as the mid 1970s when trains of rectangular RF pulses of variable durations separated by periods of free precession were used to perform frequency selective excitation in NMR, as Fourier transform‐based waveforms were hard to compute and used up valuable data storage space.…”

Section: Sms Rf Pulsesmentioning

confidence: 99%

Simultaneous multislice (SMS) imaging techniques

Barth

Breuer

Koopmans

et al. 2015

Magnetic Resonance in Med

Self Cite

441

459

View full text Add to dashboard Cite

Simultaneous multislice imaging (SMS) using parallel image reconstruction has rapidly advanced to become a major imaging technique. The primary benefit is an acceleration in data acquisition that is equal to the number of simultaneously excited slices. Unlike in‐plane parallel imaging this can have only a marginal intrinsic signal‐to‐noise ratio penalty, and the full acceleration is attainable at fixed echo time, as is required for many echo planar imaging applications. Furthermore, for some implementations SMS techniques can reduce radiofrequency (RF) power deposition. In this review the current state of the art of SMS imaging is presented. In the Introduction, a historical overview is given of the history of SMS excitation in MRI. The following section on RF pulses gives both the theoretical background and practical application. The section on encoding and reconstruction shows how the collapsed multislice images can be disentangled by means of the transmitter pulse phase, gradient pulses, and most importantly using multichannel receiver coils. The relationship between classic parallel imaging techniques and SMS reconstruction methods is explored. The subsequent section describes the practical implementation, including the acquisition of reference data, and slice cross‐talk. Published applications of SMS imaging are then reviewed, and the article concludes with an outlook and perspective of SMS imaging. Magn Reson Med 75:63–81, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.

show abstract

“…The obtained contrast of the 3D TSE appears reduced when compared to standard 2D TSE [5]. This can be both due to the increased magnetization transfer contrast present on resonance 2D T 2 weighted imaging [6] or to the mixed T 2 − T 1 contrast in the presence of the long echo trains used in 3D TSE imaging.…”

Section: Discussionmentioning

confidence: 95%

“…Dynamic k T -points were inserted into the TSE sequence to acquire in vivo images at 7T. Results The improvement provided by the dynamic k Tpoints over the static k T -point design and conventional hard 1 3 SAR [6] or 3D-TSE implementations with long RF pulse trains. The presence of spatial B 1 + inhomogeneities at high field results in signal voids and different degrees of contrast between tissues throughout the volume as has been reported and is visible in several studies [5,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

3D T 2-weighted imaging at 7T using dynamic kT-points on single-transmit MRI systems

Eggenschwiler

O’Brien

Gallichan

et al. 2016

Magn Reson Mater Phy

View full text Add to dashboard Cite

pulses was demonstrated via simulations. Images acquired with dynamic k T -points showed systematic improvement of signal and contrast at 7T over regular TSE-especially in cerebellar and temporal lobe regions without the need of parallel transmission. Conclusion Designing dynamic k T -points for a 3D TSE sequence allows the acquisition of T 2 -weighted brain images on a single-transmit system at ultra-high field with reduced dropout and only mild residual effects due to the B 1 + inhomogeneity.

show abstract

Application of PINS radiofrequency pulses to reduce power deposition in RARE/turbo spin echo imaging of the human head

Abstract: PINS RF pulses combined with multiband imaging reduce SAR sufficiently to enable routine TSE imaging at 7T within clinically acceptable acquisition times. In general, the combination of multiband imaging with PINS RF pulses represents a method to reduce total RF power deposition.

Cited by 43 publications

References 32 publications

Fast model‐based T₂ mapping using SAR‐reduced simultaneous multislice excitation

Fast model‐based T₂ mapping using SAR‐reduced simultaneous multislice excitation

Simultaneous multislice (SMS) imaging techniques

3D T 2-weighted imaging at 7T using dynamic kT-points on single-transmit MRI systems

Contact Info

Product

Resources

About

Application of PINS radiofrequency pulses to reduce power deposition in RARE/turbo spin echo imaging of the human head

Abstract: PINS RF pulses combined with multiband imaging reduce SAR sufficiently to enable routine TSE imaging at 7T within clinically acceptable acquisition times. In general, the combination of multiband imaging with PINS RF pulses represents a method to reduce total RF power deposition.

Cited by 43 publications

References 32 publications

Fast model‐based T2 mapping using SAR‐reduced simultaneous multislice excitation

Fast model‐based T2 mapping using SAR‐reduced simultaneous multislice excitation

Simultaneous multislice (SMS) imaging techniques

3D T 2-weighted imaging at 7T using dynamic kT-points on single-transmit MRI systems

Contact Info

Product

Resources

About

Fast model‐based T₂ mapping using SAR‐reduced simultaneous multislice excitation

Fast model‐based T₂ mapping using SAR‐reduced simultaneous multislice excitation