Fast oxygen-enhanced multislice imaging of the lung using parallel acquisition techniques

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

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Comparison of intracranial 3D-ToF-MRA with and without parallel acquisition techniques at 1.5T and 3.0T

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren ◽

10.1055/s-2004-820816 ◽

2004 ◽

Vol 176 (03) ◽

Author(s):

J Gaa ◽

S Weidauer ◽

M Requardt ◽

B Kiefer ◽

H Lanfermann ◽

...

Keyword(s):

Parallel Acquisition ◽

Tof Mra

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Multislice imaging of gastrointestinal stromal tumors

10.32512/jmr.1.1.2018/3.14 ◽

2018 ◽

pp. 3-14

Keyword(s):

Computed Tomography ◽

Key Words ◽

Gold Standard ◽

Gastrointestinal Stromal Tumors ◽

Mesenchymal Tumors ◽

Stromal Tumors ◽

Preferential Localization ◽

Multislice Imaging ◽

Computed Tomography Diagnosis

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the digestive tract (1%). These tumors express the CD 117 in 95% of cases. The stomach is the preferential localization (70%). Diagnosis is difficult and sometimes late. Progress of imaging has greatly improved the management and the prognosis. Computed tomography (CT) is the gold standard for diagnosis, staging, and treatment follow-up. The increasing recognition of GIST’s histopathology and the prolonged survival revealed some suggestive imaging aspects. Key words: gastro-intestinal stromal tumors; computed tomography; diagnosis

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Reducing SAR in 7T brain fMRI by circumventing fat suppression while removing the lipid signal through a parallel acquisition approach

Scientific Reports ◽

10.1038/s41598-021-94692-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Amir Seginer ◽

Edna Furman-Haran ◽

Ilan Goldberg ◽

Rita Schmidt

Keyword(s):

Fat Suppression ◽

Planar Imaging ◽

Brain Images ◽

Water Separation ◽

Parallel Acquisition ◽

Functional Studies ◽

Spatial Shift ◽

Lipid Signal ◽

Repetition Time ◽

Slice Method

AbstractUltra-high-field functional magnetic resonance imaging (fMRI) offers a way to new insights while increasing the spatial and temporal resolution. However, a crucial concern in 7T human MRI is the increase in power deposition, supervised through the specific absorption rate (SAR). The SAR limitation can restrict the brain coverage or the minimal repetition time of fMRI experiments. In the majority of today’s studies fMRI relies on the well-known gradient-echo echo-planar imaging (GRE-EPI) sequence, which offers ultrafast acquisition. Commonly, the GRE-EPI sequence comprises two pulses: fat suppression and excitation. This work provides the means for a significant reduction in the SAR by circumventing the fat-suppression pulse. Without this fat-suppression, however, lipid signal can result in artifacts due to the chemical shift between the lipid and water signals. Our approach exploits a reconstruction similar to the simultaneous-multi-slice method to separate the lipid and water images, thus avoiding undesired lipid artifacts in brain images. The lipid-water separation is based on the known spatial shift of the lipid signal, which can be detected by the multi-channel coils sensitivity profiles. Our study shows robust human imaging, offering greater flexibility to reduce the SAR, shorten the repetition time or increase the volume coverage with substantial benefit for brain functional studies.

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