02/06/2003 – The Image of the Week was submitted by Steve Kalloger, Dr. Harvey Coxson, and Dr. John Mayo of the CORE 4 facility at Vancouver General Hospital. In an effort to improve the diagnosis of pulmonary embolism, this group is researching techniques that involve the subtraction of two images (contrast enhanced and non-contrast enhanced) to better visualize perfusion defects in the lung parenchyma. This false-colorized image was created by acquiring many images at one anatomical location in the lung over time during the infusion of contrast media. Then an image acquired before the contrast media is injected is subtracted from the image with the greatest enhancement due to the contrast media and a color assigned to indicate the degree of enhancement. On the viewer’s right side of the image, the uniform blue colour indicates the presence of a large pulmonary perfusion defect. In contrast, the multiple colours on the viewer’s left side indicates no perfusion defect is present, and consequently, normal blood-flow. One may also notice the gravitational dependence effects for blood-flow on the viewers left side.

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