7T: Physics, safety, and potential clinical applications

Kraff, Oliver; Quick, Harald H.

doi:10.1002/jmri.25723

Cited by 103 publications

(112 citation statements)

References 121 publications

Supporting

Mentioning

107

Contrasting

Unclassified

Order By: Relevance

“…Unlike the preclinical setting, clinical imaging studies often have hardware, safety (eg, specific absorption rate [SAR], cardiac limits, peripheral nerve stimulation), and time limitations (eg, scan duration, breath‐hold) that can impact imaging protocol design to achieve equivalent imaging measures. High‐field clinical scanners (≥7T) can also aggravate B 0 and B 1 field inhomogeneities, resulting in regional variations in flip angle and signal intensity across the imaging volume . Additional challenges that may impede quantitative imaging in the clinical setting include implantable devices (eg, pacemakers) or patients who suffer claustrophobia or anxiety, which may impose additional limitations on field strength or imaging sequences.…”

Section: Technical Considerationsmentioning

confidence: 99%

“…High-field clinical scanners (≥7T) can also aggravate B 0 and B 1 field inhomogeneities, resulting in regional variations in flip angle and signal intensity across the imaging volume. 8 Additional challenges that may impede quantitative imaging in the clinical setting include implantable devices (eg, pacemakers) or patients who suffer claustrophobia or anxiety, which may impose additional limitations on field strength or imaging sequences.…”

Section: Challenges In Using Mri To Characterize Cancer In the Preclimentioning

confidence: 99%

See 1 more Smart Citation

Translating preclinical MRI methods to clinical oncology

Hormuth

Sorace

Virostko

et al. 2019

Magnetic Resonance Imaging

View full text Add to dashboard Cite

The complexity of modern in vivo magnetic resonance imaging (MRI) methods in oncology has dramatically changed in the last 10 years. The field has long since moved passed its (unparalleled) ability to form images with exquisite soft‐tissue contrast and morphology, allowing for the enhanced identification of primary tumors and metastatic disease. Currently, it is not uncommon to acquire images related to blood flow, cellularity, and macromolecular content in the clinical setting. The acquisition of images related to metabolism, hypoxia, pH, and tissue stiffness are also becoming common. All of these techniques have had some component of their invention, development, refinement, validation, and initial applications in the preclinical setting using in vivo animal models of cancer. In this review, we discuss the genesis of quantitative MRI methods that have been successfully translated from preclinical research and developed into clinical applications. These include methods that interrogate perfusion, diffusion, pH, hypoxia, macromolecular content, and tissue mechanical properties for improving detection, staging, and response monitoring of cancer. For each of these techniques, we summarize the 1) underlying biological mechanism(s); 2) preclinical applications; 3) available repeatability and reproducibility data; 4) clinical applications; and 5) limitations of the technique. We conclude with a discussion of lessons learned from translating MRI methods from the preclinical to clinical setting, and a presentation of four fundamental problems in cancer imaging that, if solved, would result in a profound improvement in the lives of oncology patients. Level of Evidence: 5 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1377–1392.

show abstract

Section: Technical Considerationsmentioning

confidence: 99%

Section: Challenges In Using Mri To Characterize Cancer In the Preclimentioning

confidence: 99%

Translating preclinical MRI methods to clinical oncology

Hormuth

Sorace

Virostko

et al. 2019

Magnetic Resonance Imaging

View full text Add to dashboard Cite

show abstract

“…Recently, first clinical 7T MRI systems have been introduced. This development will very likely lead to a substantial increase in the number of approximately 60‐70 ultra‐high field (UHF) MRI research systems with 7T magnets that are installed worldwide and further boost clinical and related research activities. UHF MRI at 7T and above provides advantages regarding signal‐to‐noise ratio (SNR) that can be invested to increase spatial or temporal resolution or a tradeoff thereof.…”

Section: Introductionmentioning

confidence: 99%

Development and evaluation of a 16‐channel receive‐only RF coil to improve 7T ultra‐high field body MRI with focus on the spine

Rietsch

Brunheim

Orzada

et al. 2019

Magnetic Resonance in Med

Self Cite

View full text Add to dashboard Cite

Purpose A 16‐channel receive (16Rx) radiofrequency (RF) array for 7T ultra‐high field body MR imaging is presented. The coil is evaluated in conjunction with a 16‐channel transmit/receive (16TxRx) coil and additionally with a 32‐channel transmit/receive (32TxRx) remote body coil for RF transmit and serving as receive references. Methods The 16Rx array consists of 16 octagonal overlapping loops connected to custom‐built detuning boards with preamplifiers. Performance metrics like noise correlation, g‐factors, and signal‐to‐noise ratio gain were compared between 4 different RF coil configurations. In vivo body imaging was performed in volunteers using radiofrequency shimming, time interleaved acquisition of modes (TIAMO), and 2D spatially selective excitation using parallel transmit (pTx) in the spine. Results Lower g‐factors were obtained when using the 16Rx coil in addition to the 16TxRx array coil configuration versus the 16TxRx array alone. Distinct signal‐to‐noise ratio gain using the 16Rx coil could be demonstrated in the spine region both for a comparison with the 16TxRx coil (>50% gain) in vivo and the 32TxRx coil (>240% gain) in a phantom. The 16Rx coil was successfully applied to improve anatomical imaging in the abdomen and 2D spatially selective excitation in the spine of volunteers. Conclusion The novel 16‐channel Rx‐array as an add‐on to multichannel TxRx RF coil configurations provides increased signal‐to‐noise ratio, lower g‐factors, and thus improves 7T ultra‐high field body MR imaging.

show abstract

“…While most of the clinical applications relies on images acquired at 1.5 or 3 Tesla (T) scanners, the enhanced contrast and signal-to-noise ratio (SNR) provided by ultra-high field (UHF, ≥7T) MRI can be highly attractive for musculoskeletal imaging [8]. The increased SNR can be traded to increase the spatial resolution of the images [9] or to decrease the scan time [10] (although the T1 relaxation is longer at UHF, higher levels of accelerations can used due to the increased SNR). On the other hand, the increased B 1 + (circularly polarized magnetic field responsible for excitation) inhomogeneities, increased chemical shift, and increased peak and average specific absorption ratio (SAR) present great challenges in the translation of the UHF research to a reliable clinical standard [11].…”

Section: Introductionmentioning

confidence: 99%

A new RF transmit coil for foot and ankle imaging at 7T MRI

Santini

Kim

Wood

et al. 2018

Magnetic Resonance Imaging

View full text Add to dashboard Cite

A four-channel Tic-Tac-Toe (TTT) transmit RF coil was designed and constructed for foot and ankle imaging at 7T MRI. Numerical simulations using an in-house developed FDTD package and experimental analyses using a homogenous phantom show an excellent agreement in terms of B1 + field distribution and s-parameters. Simulations performed on an anatomically detailed human lower leg model demonstrated an B1+ field distribution with a coefficient of variation (CV) of 23.9%/15.6%/28.8% and average B1 + of 0.33 μT/0.56 μT/0.43 μT for 1 W input power (i.e., 0.25 W per channel) in the ankle/calcaneus/mid foot respectively. In-vivo B1 + mapping shows an average B1 + of 0.29 μT over the entire foot/ankle. This newly developed RF coil also presents acceptable levels of average SAR (0.07 W/kg for 10 g per 1 W of input power) and peak SAR (0.34 W/kg for 10 g per 1 W of input power) over the whole lower leg. Preliminary in-vivo images in the foot/ankle were acquired using the T2-DESS MRI sequence without the use of a dedicated receive-only array.

show abstract

7T: Physics, safety, and potential clinical applications

Abstract: 4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1573-1589.

Cited by 103 publications

References 121 publications

Translating preclinical MRI methods to clinical oncology

Translating preclinical MRI methods to clinical oncology

Development and evaluation of a 16‐channel receive‐only RF coil to improve 7T ultra‐high field body MRI with focus on the spine

A new RF transmit coil for foot and ankle imaging at 7T MRI

Contact Info

Product

Resources

About