Using Ratios

Introduction

Use ratios with ruler annotations to create ratio measurements that aid in measuring anatomy. There are three ratio measurements available:

  • Ratio
  • Horizontal Ratio
  • Vertical Ratio

Note:
  • Ratio measurements are not available for Advanced Reporting (AR) studies.
  • Ratio measurements are not available for images that have no pixel spacing (and therefore, no measurement value).
  • Ratio rulers display as regular rulers in Synapse versions 7.2 and earlier.
  • Ratio rulers are based on the original orientation of the image.

For example:

  • Use Horizontal ratio to calculate the Cardiothoracic ratio on a PA Chest X-ray.
  • Use Vertical ratio to calculate the pelvic tilt in an X-ray image of the hip of a standing patient.

Steps

  1. Right-click the image to display a context menu.
  2. Select Ratio, Horizontal Ratio, or Vertical Ratio.
  3. On the image, click and hold the left-mouse button at the point where you want to start the measurement. You are now in create ratio ruler mode.
  4. Move the mouse to the point where you want to end the measurement.

Note:

For more information on creating and manipulating rulers, see Using the Ruler.
  1. Release the mouse button.
  2. Optional: After you create a ratio annotation, you can delete, move, resize, or change the measurement units. See Manipulating Annotations.

Additional Information

Annotation Option

Description

Ratio

Provides the following measurements:

  • Length of the Ratio ruler
  • Ratio: Length of the ratio ruler divided by length of the base ruler, denoted by r
  • Difference: Length of the ratio ruler subtracted by length of the base ruler, denoted by Δ

Horizontal Ratio

Provides the following measurements:

  • Length of the Horizontal ratio ruler
  • Ratio: Horizontal component of the ratio ruler divided by horizontal component of the base ruler, denoted by hr
  • Difference: Horizontal component of the ratio ruler subtracted by horizontal component of Base Ruler, denoted by Δh

Vertical Ratio

Provides the following measurements:

  • Length of the Vertical ratio ruler
  • Ratio: Vertical component of the ratio ruler divided by vertical component of the base ruler, denoted by vr
  • Difference: Vertical component of the ratio ruler subtracted by vertical component of the base ruler, denoted by Δv

Note:
  • You can only draw one ratio for each base ruler.
  • If you right-click a ratio for a base ruler and select a ratio option that differs from the current ratio type, Synapse updates the numbers to match the new ratio.
  • If you delete the base ruler or ratio ruler, Synapse deletes the other, associated ruler.
  • When you change the base ruler or ratio ruler, Synapse updates the ratio and delta values to match the changes.
  • You can create the ratio ruler in the same viewport as the base ruler, or in a different viewport from its base ruler. If the ratio ruler is created in a different viewport from its base ruler, when you save and close the study and then reopen the study, Synapse does not save the ratio association. The two rulers display as independent measurements.

Results

As you complete the Ratio annotation on an image, Synapse displays the ratio and delta values following the letter index (for example, (b) ) and displays a length annotation value in an ordered list in the Results overlay.

Related Topics

Using the Ruler