A robust SSFP technique for fMRI at ultra-high field strengths
A non-balanced (nb) SSFP-based fMRI method based on CE-FAST is presented to alleviate some shortcomings of high spatial-specificity techniques commonly used in high static magnetic fields. The proposed sequence does not suffer from the banding artifacts inherent to balanced (b) SSFP, has low geometrical distortions and SAR compared to spin-echo EPI, and in contrast to previous nbSSFP implementations, is applied at a TR, theoretically prescribed for the optimum contrast. Its non-balanced gradient was chosen to just dephase the unwanted signal component (2 π dephasing per TR per voxel). (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 19, 2018 Category: Radiology Authors: Vahid Malekian, Abbas Nasiraei-Moghaddam, Mahdi Khajehim Tags: Technical note Source Type: research
Study of lipid metabolism by estimating the fat fraction in different breast tissues and in various breast tumor sub-types by in vivo 1H MR spectroscopy
To evaluate the utility of fat fraction (FF) for the differentiation of different breast tissues and in various breast tumor subtypes using in vivo proton (1H) magnetic resonance spectroscopy (MRS). (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 15, 2018 Category: Radiology Authors: Khushbu Agarwal, Uma Sharma, Sandeep Mathur, Vurthaluru Seenu, Rajinder Parshad, Naranamangalam R. Jagannathan Tags: Original contribution Source Type: research
Impact of baseline CO2 on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation
Neurovascular coupling describes the cascade between neuronal activity and subsequent Blood-Oxygenation-Level-Dependent (BOLD) signal increase.Based on this premise, the correlation of this BOLD signal increase with a particular task, such as finger-tapping, is used to map neuronal activation. This signal increase may be dampened in brain areas exhibiting impaired cerebrovascular reactivity (BOLD-CVR), leading to false negative activation. Blood-oxygenation-level-dependent (BOLD) cerebrovascular reactivity (CVR) has also been used to optimize task evoked BOLD signal changes. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 13, 2018 Category: Radiology Authors: Christiaan Hendrik Bas van Niftrik, Marco Piccirelli, Oliver Bozinov, Nicolai Maldaner, Catherine Strittmatter, Athina Pangalu, Antonios Valavanis, Luca Regli, Jorn Fierstra Source Type: research
Impact of baseline CO2 on Blood-Oxygenation-Level-Dependent MRI measurements of cerebrovascular reactivity and task-evoked signal activation
Neurovascular coupling describes the cascade between neuronal activity and subsequent Blood-Oxygenation-Level-Dependent (BOLD) signal increase.Based on this premise, the correlation of this BOLD signal increase with a particular task, such as finger-tapping, is used to map neuronal activation. This signal increase may be dampened in brain areas exhibiting impaired cerebrovascular reactivity (BOLD-CVR), leading to false negative activation. Blood-oxygen-level-dependent (BOLD) cerebrovascular reactivity (CVR) has also been used to optimize task evoked BOLD signal changes. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 13, 2018 Category: Radiology Authors: Christiaan Hendrik Bas van Niftrik, Marco Piccirelli, Oliver Bozinov, Nicolai Maldaner, Catherine Strittmatter, Athina Pangalu, Antonios Valavanis, Luca Regli, Jorn Fierstra Source Type: research
Three-dimensional arterial spin labeling imaging with a DANTE preparation pulse
On arterial spin-labeled (ASL) images, areas of bright intravascular signal will appear when the post labeling delay time is shorter than arterial transit time. Vascular suppression (VS) schemes reduce artefactual bright signal by dephasing intravascular labeled spins. However, existing VS methods, such as Motion-Sensitized Driven-Equilibrium (MSDE), decrease the uniformity of the signal intensity distribution and extend the echo time. The purpose of this study is to compare VS using a Delays Alternating with Nutation for Tailored Excitation (DANTE) preparation pulse, with MSDE for ASL imaging on a flow phantom and volunte...
Source: Magnetic Resonance Imaging - February 12, 2018 Category: Radiology Authors: Tsuyoshi Matsuda, Hirohiko Kimura, Hiroyuki Kabasawa, Masayuki Kanamoto Tags: Original contribution Source Type: research
The prognostic value of proton magnetic resonance spectroscopy in term newborns treated with therapeutic hypothermia following asphyxia
In their recent manuscript Sijens et al. describe MRS of asphyxiated neonates treated by therapeutic hypothermia in association with outcome [1]. They conclude that lactate levels had no relationship with outcome. This is in sharp contrast with our recent findings. ROC analysis with an area under the curve (AUC) of 0.89 indicated that a Lac/NAA ratio of>0.40 was associated with an adverse outcome [2]. By looking at the 1H-MR spectra of our recent fullterm infant with severe perinatal asphyxia examined on the 3rd day after birth (Fig. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 6, 2018 Category: Radiology Authors: Floris Groenendaal Tags: Letter to the Editor Source Type: research
Referenced MR thermometry using three-echo phase-based fat water separation method
A three-point image reconstruction method for internally referenced MR thermometry was developed. The technique exploits the fact that temperature-induced changes in the water resonance frequency are small relative to the chemical shift difference between water and fat signals. This property enabled the use of small angle approximations to derive an analytic phase-based fat-water separation method for MR thermometry. Ethylene glycol and cream cool-down experiments were performed to validate measurement technique. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 4, 2018 Category: Radiology Authors: Lorne W. Hofstetter, Desmond T.B. Yeo, W. Thomas Dixon, Luca Marinelli, Thomas K. Foo Tags: Original contribution Source Type: research
Referenced MR Thermometry Using Three-Echo Phase-Based Fat Water Separation Method
A three-point image reconstruction method for internally referenced MR thermometry was developed. The technique exploits the fact that temperature-induced changes in the water resonance frequency are small relative to the chemical shift difference between water and fat signals. This property enabled the use of small angle approximations to derive an analytic phase-based fat-water separation method for MR thermometry. Ethylene glycol and cream cool-down experiments were performed to validate measurement technique. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 4, 2018 Category: Radiology Authors: Lorne W. Hofstetter, Desmond T.B. Yeo, W. Thomas Dixon, Luca Marinelli, Thomas K. Foo Source Type: research
Distortion-free diffusion tensor imaging for evaluation of lumbar nerve roots: Utility of direct coronal single-shot turbo spin-echo diffusion sequence
Diffusion tensor imaging (DTI) based on a single-shot echo planer imaging (EPI-DTI) is an established method that has been used for evaluation of lumbar nerve disorders in previous studies, but EPI-DTI has problems such as a long acquisition time, due to a lot of axial slices, and geometric distortion. To solve these problems, we attempted to apply DTI based on a single-shot turbo spin echo (TSE-DTI) with direct coronal acquisition. Our purpose in this study was to investigate whether TSE-DTI may be more useful for evaluation of lumbar nerve disorders than EPI-DTI. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - February 3, 2018 Category: Radiology Authors: Takayuki Sakai, Kunio Doi, Masami Yoneyama, Atsuya Watanabe, Tosiaki Miyati, Noriyuki Yanagawa Tags: Original contribution Source Type: research
Cluster-level statistical inference in fMRI datasets: The unexpected behavior of random fields in high dimensions
Identifying regional effects of interest in MRI datasets usually entails testing a priori hypotheses across many thousands of brain voxels, requiring control for false positive findings in these multiple hypotheses testing. Recent studies have suggested that parametric statistical methods may have incorrectly modeled functional MRI data, thereby leading to higher false positive rates than their nominal rates. Nonparametric methods for statistical inference when conducting multiple statistical tests, in contrast, are thought to produce false positives at the nominal rate, which has thus led to the suggestion that previously...
Source: Magnetic Resonance Imaging - February 3, 2018 Category: Radiology Authors: Ravi Bansal, Bradley S. Peterson Tags: Original contribution Source Type: research
