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LCD monitor

Description

The LCD monitor is a MRI conditional monitor positioned at the back of the magnet bore. It enables the researcher to present stimuli to or entertain the participant inside the bore. The video displayed to the system can be selected using the AVS or the AVI hub of the LCD monitor.

The LCD monitor is MR conditional, it can be positioned close to the magnet. The power supply to which it is connected in the scanner room must be positioned at a certain distance of the scanner. Important MR safety information can be found in the User Guide.

Device

MRI compatible LCD display - BOLDScreen 32 UHD (Cambridge Research Systems) - MRI Compatible displays with deterministic timing, integrated calibration and no interference with the MR scanner. - User Guide - Manufacturer Website

Components

The system contains three main components. Other components are used for powering the systems.

  1. Monitor mounted on Wide Trolley

    A mobile setup containing the monitor which is located inside the scanner room at the back of the bore.

    Wide Trolley

  2. AVI hub (Audio Video Interface)

    The device in the console room to control the functionality of the monitor.

    Avi Hub

  3. Hybrid cable

    A special cable carrying electrical and optical signals. The hybrid cable connects the trolley to the AVI hub and penetrates the Faraday's cage for that purpose.

    Hybrid Cable

Positioning

Optimal distance

The optimal position of the monitor relative to the magnet depends on the visual angle required from the display and/or the required visible area of the display.

One can easily calculate the optimal position of the monitor using the image and formula below.

Visual Angle
\[ d_2 = d_1(W/B-1) \]
Parameter Description
B diameter of bore
d1 distance between the viewing position and end of the bore including the distance between the eyes of the subject and the head coil mirror
d2 distance between end of bore and monitor
W width of active area

For the setup at GIfMI:

  • The active region of the monitor, i.e. the area filled by the video, is 69.84 x 39.29 cm, the diagonal is 80.1 m.
  • The approximate distance from the eye of the participant to the end of the bore is around 125 cm.
Bore Diameter (B) Screen area visible (W) Offset from end of bore d2 Horizontal visual angle Vertical visual angle
60 cm 69.84 cm
(Full Width)		 16,4 cm 33,4° 19,2°
60 cm 80.10 cm
(Full Area)		 33,5 cm 29,3° 16,7°

The visual angle was calculated using the visual angle calculator of SR Research, manufacturer of the EyeLink eyetracking system.

Here are some examples of how the position of the monitor (black rectangle) relative to the exit of the magnet bore (grey circle) affects the visible region (blue) when viewed from inside the bore.

  • Top left: monitor positioned so that full width is visible (16.4 cm offset)
  • Top right: monitor positioned so that full area is visible (33.5 cm offset)
  • Bottom left: monitor at end of 60cm bore (0 cm offset)
  • Bottom right: monitor positioned further than distance calculated (>33.5 cm offset)

Visible Area

Note

We will tape the distances for full width and full area visibility on the ground. Pictures of the location will be added later.

Moving the monitor

When pushing the trolley with the monitor attached, do this slowly and carefully. Use two hands, one at the top of the upright and one further down. Note that eddy currents near the magnet may cause resistance to motion in some directions. When positioning the monitor, ensure that all four castors are on the floor.

The monitor and trolley can be pushed up against the magnet housing if necessary, and doing this will limit movement of the monitor in the event of a magnet quench.

Warning

Under no circumstances should the hybrid or DC cable be inside the magnet bore, be touching, or be within reach of the patient/participant being scanned.

Operation

This section describes the basic functionality and most important tips and tricks to use the system. We refer to the user manual for detailed information.

Control panels

The LCD monitor and AVI hub are fitted with panels with connectors and buttons to control the system. The function of the relevant buttons is explained further.

Warning

All connections to the devices are permanent and should remain untouched for proper operation!

  1. LCD monitor

    The control panel of the LCD monitor can be found at the back of the monitor. All connections to the control panel are permanent and should remain untouched.

    LCD monitor back panel

    Label Description
    Power button Turn on/off the system, see Turning on/off the system
    Status LED Display the current status, see Status LEDs
    DC in Power cable, permanent connection
    USB 2 USB connectors, unused
    Fibre video Connection to the AVI Hub via the Hybrid cable

  2. AVI Hub

    The AVI Hub contains a front and back panels.

    Label Type Description
    Power In Button Turn on/off the system, see Turning on/off the system
    USB-C Input Multi-purpose USB-C selector, see Connecting and selecting video and Camera view
    DisplayPort Input DisplayPort 1.4 interface
    HDMI-1 Input HDMI 2.0 interface (default connection: output 4 of the AVS)
    HDMI-2 Input HDMI 2.0 interface
    Mirror mode Button Mirrors the image left to right, necessary for the setup at GIfMI.

    Label Connector Description
    BS32 UHD Special Connection to the AVI Hub, permanent connection
    1GbE RJ45 Ethernet connection, unused
    Camera HDMI Camera stream from the LCD monitor, connected to VID/I1 on the BOX
    Clone HDMI Clone of the selected input source, unused
    USB-3 USB-A USB port available when connecting with the USB-C port on the front panel, unused
    Audio 3.5mm TRS jack Analog stream of HDMI embedded audio
    S/PDIF Toslink Digital stream of HDMI embedded audio
    Scanner BNC jack TTL trigger from the scanner, sends character T, unused because of custom system
    Power In USB-C Turn on/off the system, see the section
    Reset Button Reset the device to factory settins

Turning on/off the system

The system has three power states:

State Description
Standby The monitor is in low power mode. The LCD panel and backlight are not powered, but some of the internal electronics are still active. The status LED will blink green. This is the default state when power is connected.
On All components of the monitor are powered on. The status LED will be solid green. If the monitor receives a valid video signal, an image will be displayed and the status LED will turn solid blue.
Off All but the minimum electronics required to power on the monitor are off.

  1. LCD monitor power button

    Pressing this button will cycle the monitor through the three power states described above. Standby is the default state at power on, so a single press will be required to switch to On before an image can be seen. However, it is expected that users will control the power state from the AVI hub and will not need to routinely use the monitor power button.

  2. AVI hub power button

    Pressing this button will toggle the AVI hub between Standby and On. It also sends these commands to the monitor so the system can be toggled from the AVI hub only.

  3. When not in use

    The system can be left in Standby between uses. This is mandatory as leaving the system in the On state when not in use shortens the life of the LCD panel.

    Put the system in the Off state when not being used for longer periods, e.g. overnight.

If the system does not turn on or the Status LED does not turn solid blue, check the Status LEDs and inform the GIfMI site manager.

Connecting and selecting a video source

The AVI Hub has four inputs as described in the Control Panels section.

DisplayPort

The supported version is DisplayPort 1.4.

HDMI-1 and HDMI-2

The supported version on both ports is HDMI 2.0.

By default, the output of output 4 of the AVS is connected to HDMI-1. This should not be altered as this is the default setup for the majority of the users.

USB-C

The USB-C port accepts video signals in DisplayPort Alt Mode and can be connected to a laptop or phone with a USB-C or Thunderbolt 3 or 4 connector with video output. It must be noted that not all devices with USB-C ports are able to output video and that not all USB-C to USB-C cables support video transmission.

The USB-C hub has multiple uses.

The requested video source can be selected by pressing the button to the right of the connector. The button will be illuminated to indicate the selected input.

The LCD monitor supports 4K resolution (3820x2160) natively. All other resolutions are rescaled. The active area of the LCD monitor will be used fully with 16:9 resolutions like FullHD (1920x1080) which is the native resolution of the stimulus PC.

Warning

Connecting an external video source directly to the AVI results in bypassing the rest of the visual system. If you wish to make use of the complete visual system, use the procedure described in the AVS section.

Camera View

The LCD monitor has 2 built-in cameras, one at the top and one at the bottom. Only one camera can be used at any one time. By default, the top camera is used a it has a better view inside the bore. Switching of the camera for specific applications is only allowed after approval of the GIfMI site manager.

The image of the built-in camera can be viewed in two ways.

  1. HDMI port on the back panel The HDMI connector on the AVI Hub back panel labelled Camera is by default connected to VID/I1 on the BOX. By using the AVS one can display the camera image to e.g. one of the displays in the console room.

  2. USB-C port on the front panel The USB-C acts as a standard webcam when connected to a laptop. No drivers are needed on modern operating systems. Use a software of choice which supports webcam image display. On Windows computers, the Camera app works perfectly fine.

The USB-C hub has multiple uses.

Audio

The de-embedded audio from the video input is currently not being used. It is however possible to connect the analog output signal, which can be found on the back panel, to the audio system via the BOX. More details to connect to the audio system can be found in the Audio system section.

Connecting peripheral devices

Connecting devices to the monitor

The monitor houses 2 USB-A connectors to which devices can be connected and which are accessible via a built-in USB hub at the USB-C port on the front panel of the AVI hub.

Warning

MR Conditional

Use only devices which have been approved by the GIfMI site manager before entering devices in the MR room!

Connecting devices to the AVI hub

When the USB-C port on the front panel of the AVI hub is connected to a computer, the following other USB devices will be detected:

  • A webcam device showing the image of the built-in camera, see the Camera View section.
  • A COM port/serial port device (virtual serial port) which allows to send commands to and receive responses from the AVI hub. See the User Guide for detailed information. This connection is not meant to be used by the standard user as using this port might corrupt the configuration of the system!
  • A keyboard which simulates keypresses when the TTL trigger receives input from the scanner. A character T will be sent for every TTL input at the Scanner trigger port. This is unused in the default setup, see the MRI Trigger section.
  • A USB hub to which all USB-A ports on the monitor and the back panel of the AVI hub are connected to.

The devices described above don't need additional drivers. The other connections on the AVI hub are not used by default.

Status LEDS

LED state Status
Off Unit is in very low power state or not connected to power.
Flashing Green Unit is in standby
Solid Green Unit is on, but not receiving video.
Solid Blue Monitor is receiving and displaying video.
Flashing Red Hardware fault detected.
Solid Red Overheating.
Flashin Yellow Firmware update in progress.
Solid Yellow Powering on.
Purple Non-volatile settings corrupted, using defaults.

Tips

  • A mirror mounted on top of one of the head coils enables the participant to look at the LCD monitor. The mirror shipped with the scanner has two configurations to look to the front or to the back of the bore. Proper positioning points the double mirror side to the front of the bore and the single mirror to the back of the bore as demonstrated here.

    64 channel head coil

  • When the monitor is positioned at the rear of the scanner and viewed by the patient via a mirror on the headcoil, the image they see will be “mirrored” (flipped left to right). This can be compensated by pressing the Mirror Mode button at the front panel of the AVI hub. The button will illuminate when the mirrorring is on.

  • The wide trolley has been chosen to easily combine with the eyetracker. Be careful when moving the systems to avoid damage. See the Eyetracker section for more information.

  • Make sure that the AVS is setup correctly and video inputs are selected correctly.

Warning

Please turn off the LCD monitor when not in use. This will increade lifetime of the backlight of the monitor. See the section Turning ON/OFF the system. //

Specifications

LCD Panel

SPECIFICATION DESCRIPTION
Panel Dual-edge (left and right) WLED backlit VA LCD panel
Active area 698.4 x 392.9 mm
Pixel dimensions 3840 x 2160 (4K UHD). Other input signals will be rescaled
Pixel Pitch 0.181 (H) x 0.181 (V) mm
Native frame frate 60Hz. Lower input framerates will be resampled
Default peak luminance 300 cdm-2
Colour resolution 10 bit RGB
Colour gamut: 95% of NTSC
Colour chromaticities (CIE 1931 x,y)
Red (0.685, 0.310)
Green (0.260, 0.685)
Blue (0.152, 0.055)
White (0.313, 0.329)
Contrast ratio 3000:1.
Grey-to-grey (GTG) response time 9,5 ms
Luminance regulation system sensor measures backlight once per second and adjusts to maintain output within 2% of set value

Cameras

SPECIFICATION DESCRIPTION
Number 2
Type CMOS
Resolution 1920x1080
Frame rate 30 Hz
Focus lens fixed at 1m
Depth-of-field Large, distance will have little effect on focus
Location see figure
Remark Only one camera can be used at any one time

LCD monitor camera locations

Electrical

SPECIFICATION DESCRIPTION REMARK
Monitor Requirement: 48V 150W Connect to supplied filter unit only
Filter Unit Input/Output: 48V 150W Connect to supplied power supply unit only
Cable IO unit Input/Output: 48V 150W Connect to supplied power supply via filter unit only
Trolley Input/Output: 48V 150W Connect to Cable IO unit only
Power supply unit Requirement: 90-264V AC, 50/60Hz
Power supply unit Input/Output: 48V 150W Conforms to EN 60601-1
AVI hub Requirements: 100-240V AC, 50/60Hz
AVI hub power supply unit Requirements: 100-240V AC, 50/60Hz
AVI hub power supply unit Output: 20V 65W

Mechanical

SPECIFICATION DESCRIPTION
Monitor
Mass 10kg
Dimensions (WxHxD) 767x463x57 mm , see image
Trolley
Mass 21kg
Dimensions see image
LCD monitor dimensions
Monitor dimensions
wide Trolley dimensions
Wide Trolley dimensions