ANI research infrastructure houses four functional neuroimaging modalities, navigated transcranial magnetic stimulation (nTMS) at Aalto TMS, functional magnetic resonance imaging (fMRI) at Advanced Magnetic Imaging (AMI) Centre, magnetoencephalography (MEG) at MEG Core and Aalto Behavioral Laboratory (ABL).
AMI Centre facilities - Miscellaneous
MRI at AMI, an introduction guide to users
Preliminary information to user groups can be found from this document.
Acoustic noise in MRI
Akukon Oy measured the acoustic noise of AMI Centre's MRI scanner (Magnetom Skyra 3.0 T) on 20th of June, 2012 (report available in PDF-document, in Finnish). A microphone was placed on a head phantom next to the phantom's ear and the noise levels of various MRI sequences were recorded as a function of time. The RF-pulses were switched off because the RF signal was found to interfere with the acoustic noise measurements. The main source of the acoustic noise is due to the gradient coils whereas the RF pulses are expected to increase the sound pressure only slightly (see e.g. Counter S.A. et al. JMRI, 7, 606-611, (1997)). However, AMI Centre will study the effect of the RF-pulses on the acoustic noise levels in more detail in near future.
We want to emphasize that these results are preliminary and they should be used merely as guidelines. Further analysis of the noise measurements will be carried out in August 2012 and the rough values shown here may change. The first eight sequences were run using the 20 channel head/neck coil and the rest using the 32 channel head coil. We have also included some user sequences which are regularly used. Further details of the measured sequences and the parameters used can be obtained from AMI Centre's personnel.
|Sequence||Comments||LAeq (dB)||LAFmax (dB)||LZpeak (dB)|
|Most typical sequences used with the 20 channel head/neck coil.|
|MPRAGE sag (MGH-variant)||94||99||110|
|EPI 64 p2 GRAPPA||103||112||139|
|EPI 64 p2||Hanna Renvall||102||105||115|
|EPI 96||Teemu Rinne||97||98||110|
|EPI 64 p2||Mia Liljeström||104||105||116|
|Foam padding on both sides of the head coil (otherwise same as previous).||98||99||108|
|Most typical sequences used with the 32-channel head coil|
|MPRAGE Lo-re Sag (p3)||109||118||139|
|MPRAGE sag (MGH-var)||gradients=fast||96||113||139|
|DTI 64dir (mddw, p2)||97||112||139|
|T2 TSE Axial||93||96||109|
|T2 TDF (FLAIR)||89||96||108|
|SPACE (T2 3D)||Could not switch off all the RF-pulses.||100||111||120|
|Effect of the matrix size.|
|EPI 64||matrix = 64 x 64||107||108||118|
|EPI 96||matrix = 96 x 96||107||108||115|
|EPI 128||matrix = 128 x 128||110||111||117|
|Effect of the parallel imaging and the accelaration factor.|
|EPI 64, p2 GRAPPA||Parallel imaging||107||108||118|
|EPI 64, p3 GRAPPA||105||106||118|
|EPI 64, p4 GRAPPA||103||103||116|
|EPI 64 p2 mSENSE||107||108||119|
|Effect of using the whole 32 channel head coil vs. only the posterior part.|
|EPI 64 p2, 2.0 mm slice||Posterior + anterior||106||106||116|
|Effect of the gradient mode.|
|EPI 64 p2 GRAPPA||Gradients = fast||107||108||119|
|Gradients = normal||105||106||115|
|Effect of the TE.|
|EPI 64 p2 GRAPPA||TE = 13 ms||107||108||117|
|TE = 20 ms||107||108||118|
|TE = 30 ms||106||106||116|
|Effect of the TR (with maximum number of slices)|
|EPI 64 p2 GRAPPA||TR = 100 ms||105||106||116|
|TR = 1000 ms||105||106||116|
|TR = 3000 ms||105||106||116|
|Effect of the number of slices|
|EPI 64 p2 GRAPPA||Number of slices = 5||99||104||119|
|Number of slices = 20||105||106||119|
|Number of slices = 35||107||109||119|
|Effect of the slice thickness|
|EPI 64 p2 GRAPPA||Slice thickness = 2.0 mm||106||106||116|
|Slice thickness = 3.0 mm||106||113||139|
|Slice thickness = 4.0 mm||106||106||116|
|Effect of the field of view|
|EPI 64 p2 GRAPPA||FoV = 129 mm||98||99||111|
|FoV = 129 mm||102||103||116|
|FoV = 129 mm||100||101||113|
|Effect of the echo spacing|
|EPI 64 p2 GRAPPA||Echo spacing = 0.50 ms||108||113||140|
|Echo spacing = 0.55 ms||103||104||115|
|Echo spacing = 0.60 ms||103||104||113|
|EPI 64 p2||Elvira Brattico||107||108||119|
|ep2d_32ch_41volumes||Simo Vanni (PMRIQUAD)||116||117||127|
|EPI 64 spin-echo||Lauri Nurminen||104||105||113|
|Acoustic noise in the console room|
|EPI 64 p2||Noise in the scanner||106||106||116|
|Noise in front of the computer||45||46||72|
|Noise in front of the RF tube (empty tube)||49||51||70|
Separate preparation room
AMI Centre has a separate preparation room for users (the glass door on the left when standing in the lobby of Magnethouse). During the following times, the separate preparation room is always by definition reserved for the user/group that has made a reservation of the magnet:
a) half an hour before their scheduled magnet reservation starts (15 minutes if the previous reservation is only one 30-min slot)
b) half an hour after their scheduled magnet reservation ends (15 minutes it the next group has reserved only one 30-min slot).
All the other times must be discussed and agreed with the reserving group if you want/need to deviate from this prioritization (check contact information from the reservation calendar).
Please note that this policy means that the reserving group cannot use the separate preparation room immediately after their magnet reservation starts or just before their magnet reservation ends, because the previous/next group then has the priority to the separate preparation room so that they can do preparations for measurement or finish their interviews etc. If there are no previous/following magnet reservations, then you can use it, of course.
In which order does the Siemens scanner acquire slices? Read the below document to find out.
Aalto Behavioral Laboratory (ABL) has various different monitoring and stimulus systems for behavioral studies in controlled environment. The laboratory consists of two measurement rooms: a shielded room which is especially intended for EEG and remote eye tracking measurements; and a room for behavioral measurements which doesn’t require shielded conditions.
Aalto TMS offers researchers unique possibilities for multi-modal neuroimaging techniques. The laboratory contains top-of-the-line electroencelography (EEG) and transcranial magnetic stimulation (TMS) systems.
MEG Core offers excellent environment for MEG measurements. MEG Core has a modern 306-channel MEG device (Elekta Neuromag™, Elekta Oy, Helsinki, Finland) in a high-end 3-layered magneticaly shielded roo (Imedco AG, Hägendorf, Switzerland). MEG Core has extremely low magnetic ambient noise level. MEG Core has a wide variety of MEG-compatible stimulators and monitoring devices.