Introduction

The image viewer used on this website is a simplified version of digital MRI and X-Ray viewers that you find in hospitals and imaging centres. Learn how to use the controls by clicking through the topics using the directional arrows ( and ), and testing them out on the image sequence to the left.

Even if you have used commercial image viewing software before, it is important that you work through the entire tutorial, as it covers important concepts specific to the MRI course.

If you prefer, you may watch a video tutorial instead of reading through the text tutorial. Click the "Video Tutorial" button above to switch.

Important points before you begin

You must be using a modern Internet browser to view this course, such as the latest versions of Google Chrome, Mozilla Firefox, Microsoft Edge, or Apple Safari. Internet Explorer is not recommended, is not supported, and may not work. If you do not see an MRI image to the left, your computer and/or browser does not meet the minimum requirements to use this site. Click here to review the technical requirements.

We recommend that you use a mouse with a scroll wheel (instead of a trackpad) to interact with the images. Some of the image manipulation controls use the right mouse button, which some users find more difficult when using a trackpad.

For the best viewing experience, please maximize your browser to fill the entire screen.

Stack

MRI sequences may be made up of several slices. In the MRI course, each image sequence will have approximately 12-18 slices. Stacking allows you to move through the sequence slices. To move through the slices:

1. Select the Stacking tool
2. Move the mouse cursor into one of the images
3. Click and hold down the left mouse button.
4. While holding down the left mouse button, move your mouse up or down. Move the mouse down to move forward through the slices, and up to move backward through the slices.

Tips:

• In the MRI course, the left and right images will always be synchronized, so that scrolling in either image will scroll both.
• If your mouse has a scroll wheel, you can also scroll through the slices using the wheel (may not work in some browsers).
• You can also scroll through the slices using the scroll bar on the right side of the image.

Window

Windowing allows you to adjust the brightness and contrast of the images which can help better highlight features.

1. Select the Window tool
2. Move the mouse cursor into one of the images
3. Click and hold down the right mouse button.
4. While holding down the right mouse button, move your mouse up and down to adjust brightness, or left and right to adjust contrast.
   • Up makes the image brighter
   • Down makes the image darker
   • Left increases the contrast (dark areas get darker, light areas get lighter)
   • Right decreases the contrast (dark areas get lighter, light areas get darker).
   • Moving the mouse diagonally adjusts both brightness and contrast at the same time.

Tips:

• Windowing is applied to each sequence independently (e.g., windowing the T1 sequence does not affect the STIR sequence), but the settings are applied to all images in the selected sequence.
• Most images will benefit from an increase in contrast.

Zoom

Zooming lets you magnify the image to get a closer look at specific features.

1. Select the Zoom tool
2. Move the mouse cursor into one of the images
3. Click and hold down the right mouse button.
4. While holding down the right mouse button, move your mouse up and down to zoom in and out.

Move

The Move tool is often used in conjunction with the Zoom tool. It allows you to move a magnified image around in the viewing area.

1. Select the Move tool
2. Move the mouse cursor into one of the images
3. Click and hold down the left mouse button.
4. While holding down the left mouse button, move your mouse up, down, left, and right. The image will move with the cursor.

Annotate

The Annotate tool lets you draw lines on an image.

1. Select the Annotate tool
2. In the box that opens to the right of the tool, select a colour.
   Note: In the MRI course, we use a consistent colour scheme for identifying features:
   •  Red  for Edema
   •  Green  for Erosion
   •  Yellow  for Fat
   •  Blue  for Ankylosis
   •  Purple  for Enthesitis
3. Move the mouse cursor into one of the images
4. Click and hold down the left mouse button.
5. While holding down the left mouse button, move your mouse around. A line will be drawn on the image.

Tips:

• To remove the last annotation drawn on an image, click the button.

Reset

The Reset tool resets any manipulations made to a sequence (e.g., zoom, window), and removes all annotations.

1. Select a sequence by clicking the mouse on an image. A sequence is selected when there is a red box around it.
2. Click the Reset button.

Audio Controls

If a case has an audio track, audio controls will be displayed in the control bar. The audio track usually contains a description of the current case and points out features of the case. It is important that you listen to the audio track as you progress through the cases. Use the Pause and Rewind buttons as required so that you can interact with the images based on the audio cues. You may also view or hide the transcript of the audio track by clicking on the Transcript button.

• Play the audio track
• Pause the audio track
• If the track is playing, rewind 5 seconds. If the track is paused, rewind to the beginning.
• If the track is playing, fast-forwards 5 seconds.
• Adjust the volume
• View or hide a transcript of the audio track, if available.

Audio Controls (continued)

When a case has a transcript of the audio or a textual desciption, you may flip through the transcript using the Rewind and Fast Forward buttons in the left-hand side of the transcript box.

1. Open the transcript (if not already open) by clicking
2. Use and to navigate through the transcript

Image Features

Many cases in the MRI course will have features described in the audio track, and may have additional features that are not mentioned in the audio track. Some of these features are highlighted when you move your mouse pointer over the feature on a particular slice. In the test sequence on the left, there are instances of Fat Metaplasia in the right and left lower sacrum on slice 9. Scroll to slice 9, and move your mouse pointer over the image until you see the features highlighted.

• While the feature is highlighted, you can click on it to make the outline stick.
• Click on it again to unstick the outline.

When the audio track points out features that you are expected to find, a feature counter will appear in the menu bar telling you how many features you have found out of the total number of features hidden. The audio track will automatically pause until you have found all the features. If you get stuck, you may press Play to continue the audio.

Case Navigation

The current case number will be displayed in the top-right corner of the image viewer. Navigate through the cases using the following controls:

• Return to the module introduction/case list
• Go to the previous case
• Go to the next case

Other tips and tricks

• Maximize your browser window so that it fills the entire screen. The larger the images, the better you will be able to see the features.
• When selecting some controls, directional arrows will appear to the right of the control. You can click on these arrows to perform the same functions as moving the mouse in that direction while holding down the appropriate button.
• Because some controls are operated with the left mouse button and others with the right mouse button, you can have two controls selected at the same time, e.g., Stack and Window, or Move and Zoom.

Finished!

You have completed the Image Viewer Tutorial.