Running fMRI at MR5

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Contents

Introduction

The MRI facility MR5 at the MR Centrum in Karolinska Hospital allows to:

while running fMRI.


It is possible to display visual stimuli through Nordic Neuro Lab’s goggle system, through a video projector or on a LCD TV screen inside the MR room. Auditive stimuli can also be played through at least two different systems. Recording physiological data is also possible from two different systems. The General Electrics (GE) MR 750 Discovery has built-in ECG (4leads), a finger pulse oxymeter, and a respiration belt sensor. These data are available on-line through RS232 protocol, or can be recorded on a file while acquiring fMRI data. Another system for recording physiological data is the BIOPAC MP150 together with its amplifiers. It is then possible to record ECG, EMG, and galvanic skin response. ECG and EMG recording are very sensitive to the variation of the magnetic field inside the core of the MR scanner. Eye-tracking is possible when using the NNL goggles.

Demo paradigms

adapting/designing a paradigm for fMRI

Adapting the paradigm is certainly the most important and the most time con- suming step. One paradigm is generally changed many times between the first pilot and the start of a study. It would be unrealistic to believe that you can run your study after having installed your paradigm in the fMRI computer. Some issues about your paradigm will be detected only after the first or several pilots. It would also be unrealistic to believe that all the issues can be listed in the present document. But, in order to reduce the number of issues and to save some time and money,here is a list of some systematic modfications that you could bring to your paradigm:

design / trial lists

divide in sessions

fMRI trigger

Eye-tracking trigger


Coils @3T

Latest info: 2016 Be careful with structural image analysis when 32 ch array was used. The default parameters (FSL, SPM, FS) for image bias intensity field correction may not be relevant.

04/2014: After QA test performed on the 32 ch. MR Instrum., showed one damaged element. GE has exchanged the coil.

11/2011: After QA test performed on the 32 ch. MR Instrum., showed one damaged element. GE has exchanged the coil. New and the old 32 ch. coils were evaluated: a broken element caused a signal drop of ca. 7% (Left vs. Right) seen on high SNR 3D T1w images in the area of frontal lobe (SBI technical help). For fMRI, DTI - quality should not be affected.



brain MRI

1) 32 channels NOVA (config SI/LRxAP= 4 / 8 )

2) 32 channels MR_Instruments ( config SI/LRxAP = 2/ 16) [1]

2) 8 channels multi-element coil array form InVivo[2]

3) splited bird cage (normally used for testing, QA)

spine and neck MRI

4) HNS - Head, Neck and Spine Array There are 29 elements in 3.0T HNS Coils covering brain, neck and spine that should be used in a pre-defined configurations: Media:NHS_array_config.png

5) NVS - Neuro-vascular 8 element array

Misc. Coils: Multi-nuclear

6) 19F bird-cage for brain
7) 31P surface coil, dia: 8 cm

GE 3T Discovery MR750: tech. info.

Dimensions, can be useful for custom design of fmri equipment:

File:GE MR750 in-the-magnet.pdf

File:GE MR750 in-the-magnet iso-center.pdf


Technology[3].


Field strength/ resonance frequency.........3T / 127.8 MHz
Bore diameter...................................60 cm
Max patient load...............................159 kg

Gradient type...............................Non resonant, actively shielded, rapidly switching
Max Grad. Amplitude.........................87 mT/m
Min Rise time to Max Amplitude..............250 µsec
Max Slew Rate...............................346 T/m/s

Types of RF transmit coils..................Body Coil
Amplifier peak RMS power....................35KW
Maximum transmit bandwidth..................>0. 6 MHz


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