Purpose
Functional magnetic resonance imaging (fMRI) during infancy poses challenges due to practical, methodological, and analytical considerations. The aim of this study was to implement a hardware‐related approach to increase subject compliance for fMRI involving awake infants. To accomplish this, we designed, constructed, and evaluated an adaptive 32‐channel array coil.
Methods
To allow imaging with a close‐fitting head array coil for infants aged 1‐18 months, an adjustable head coil concept was developed. The coil setup facilitates a half‐seated scanning position to improve the infant’s overall scan compliance. Earmuff compartments are integrated directly into the coil housing to enable the usage of sound protection without losing a snug fit of the coil around the infant’s head. The constructed array coil was evaluated from phantom data using bench‐level metrics, signal‐to‐noise ratio (SNR) performances, and accelerated imaging capabilities for both in‐plane and simultaneous multislice (SMS) reconstruction methodologies. Furthermore, preliminary fMRI data were acquired to evaluate the in vivo coil performance.
Results
Phantom data showed a 2.7‐fold SNR increase on average when compared with a commercially available 32‐channel head coil. At the center and periphery regions of the infant head phantom, the SNR gains were measured to be 1.25‐fold and 3‐fold, respectively. The infant coil further showed favorable encoding capabilities for undersampled k‐space reconstruction methods and SMS techniques.
Conclusions
An infant‐friendly head coil array was developed to improve sensitivity, spatial resolution, accelerated encoding, motion insensitivity, and subject tolerance in pediatric MRI. The adaptive 32‐channel array coil is well‐suited for fMRI acquisitions in awake infants.
Background The increasing number of minimally invasive fluoroscopy-guided interventions is likely to result in higher radiation exposure for interventional radiologists and medical staff. Not only the number of procedures but also the complexity of these procedures and therefore the exposure time as well are growing. There are various radiation protection means for protecting medical staff against scatter radiation. This article will provide an overview of the different protection devices, their efficacy in terms of radiation protection and the corresponding dosimetry.
Method The following key words were used to search the literature: radiation protection, eye lens dose, radiation exposure in interventional radiology, cataract, cancer risk, dosimetry in interventional radiology, radiation dosimetry.
Results and Conclusion Optimal radiation protection always requires a combination of different radiation protection devices. Radiation protection and monitoring of the head and neck, especially of the eye lenses, is not yet sufficiently accepted and further development is needed in this field. To reduce the risk of cataract, new protection glasses with an integrated dosimeter are to be introduced in clinical routine practice.
Key Points:
Citation Format
In vivo diffusion-weighted magnetic resonance imaging is limited in signal-to-noise-ratio (SNR) and acquisition time, which constrains spatial resolution to the macroscale regime.
Ex vivo
imaging, which allows for arbitrarily long scan times, is critical for exploring human brain structure in the mesoscale regime without loss of SNR. Standard head array coils designed for patients are sub-optimal for imaging
ex vivo
whole brain specimens. The goal of this work was to design and construct a 48-channel
ex vivo
whole brain array coil for high-resolution and high
b
-value diffusion-weighted imaging on a 3T Connectome scanner. The coil was validated with bench measurements and characterized by imaging metrics on an agar brain phantom and an
ex vivo
human brain sample. The two-segment coil former was constructed for a close fit to a whole human brain, with small receive elements distributed over the entire brain. Imaging tests including SNR and G-factor maps were compared to a 64-channel head coil designed for
in vivo
use. There was a 2.9-fold increase in SNR in the peripheral cortex and a 1.3-fold gain in the center when compared to the 64-channel head coil. The 48-channel
ex vivo
whole brain coil also decreases noise amplification in highly parallel imaging, allowing acceleration factors of approximately one unit higher for a given noise amplification level. The acquired diffusion-weighted images in a whole
ex vivo
brain specimen demonstrate the applicability and advantage of the developed coil for high-resolution and high
b
-value diffusion-weighted
ex vivo
brain MRI studies.
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