JEMRIS  2.8.1
open-source MRI simulations
Coil array layout tool: JEMRIS_txrx

The GUI for coil array configuration allows to construct receiver and/or transmitter arrays with dedicated spatial sensitivity patterns. A coil array consists of several coils in a specified order, the channel number. The order is just given by the order of creation of the coils. In case of a receive coil array, one signal file per coil is generated in the simulation. In case of a transmit coil array, the RF pulses of the MR sequence have to specify which channel they use. If no channel is specified, the RF is transmitted via all available channels.

The command "JEMRIS_txrx" opens in Matlab the GUI for coil array configuration.

GUI Menus

GUI Panels

The GUI is devided in four different panels comprising all functionality:

txrx_gui.jpg

XML File Panel

On this panel the name of the current XML coil array file is displayed in red. There are two buttons:

Additionally, the output of the external jemris call is dumped below.


Sensitivity Map Panel

On this panel the sensitivity map is plotted. Note that the magnitude senstivity for each individual coil is normalized to one within the FOV of the coil (see below for a defintion of the coil FOV). Therefore, the superposition of the sensitivity may has values larger than one.

The display of the sensitivity can be manipulated with four different selection boxes:


Coil Array Panel

On the Coil Array Panel all coils of the array are displayed by green circles with their name. Click a coil to make it active for manipulation of its attributes on the Coil Panel. The active coil is marked with a surrounding red circle.

Additionally, there are three buttons:


Coil Panel

Finally, on the Coil Panel all properties (attributes) of the currently active coil are specified. Changing the attributes of a coil will only have effect after pressing the "write XML" button on the XML File Panel

Whenever an attribute value is changed, it is possible to apply this last change to all other coils by pressing the button "apply change to all".

There are several attributes which are common for all coil types:

For the next properties, which also apply to all three coil types, it is important to know how jemris internally handles coil sensitivities during the simulation. Each coil represents its sensitivity on a predefined grid which is calculated once in the beginning. Then, during simuation, the sensitivities are retrieved by linear interpolation on the grid. This is important to speed up the simulation since value retrieval has to take place at at every spin position and every time point of the MR sequence which is related to signal acquisition (in case of a receive coil) or RF pulses (in case of a transmit coil). The grid (usually the same for all coils in the array) has three attributes:


Finally there are coil attributes specific to the type of the coil:

Biot-Savart Loop

Analytic Coil

External Coil


-- last change 17.06.2016 | Tony Stoecker | Imprint --