Artikel
Methods for objective display of areas with contrast medium uptake in MRI scans
Methoden objektiver Darstellung von Arealen mit Kontrastmittelaufnahme in NMR-Bildern
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Autoren
Veröffentlicht: | 23. April 2004 |
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Gliederung
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Objective
The complete information about the localization and intensity of contrast medium (CM) uptake in MRI scans is contained in two different images, T1+CM and T1 plain. To obtain this information, which is rather metainformation, an evaluation of both images is mandatory, and is mainly performed by mental, to-and-fro, comparison. Changes in intensity stand for areas of CM uptake. We describe two techniques to objectively present this metainformation.
Methods
The first technique obtains the demanded information by subtracting both corresponding images as known and performed by the method of Digital Subtraction Angiography (DSA). The second technique applies the RGB-Transformation (red, green, blue) with the attachment of the T1+CM to the red color channel, and the T1 plain to the green and blue channels. These three color channels then are additively combined to one color image by a computer program which was developed at our clinic.
Results
The subtraction technique clearly displays the areas of CM uptake. However, adjacent anatomical structures and their relationship to the areas in question are not visible. This fact is the advantage of the latter technique: Here CM is coded in a red color whereas the surrounding tissue is clearly displayed as in the original scans. Sometimes it may appear in a light cyan hue.
Conclusions
The subtraction technique allows a quick evaluation of areas with CM uptake. Its disadvantage, however, is a poor demonstration of anatomical relationships. With the ongoing computerization of hospitals it is no problem to apply RGB-Transformation to receive optimal images with an objective display of CM-dependent changes in red within the originally included anatomical structures. The intuitive evaluation is thus more exact, easy and quick, especially in cases with only slight CM uptake.