• Object ID: 00000018WIA30A40970GYZ
  • Topic ID: id_40026693 Version: 1.3
  • Date: Feb 12, 2022 4:42:31 PM

MR-Touch

MR-Touch is a Phase Contrast (PC) application that generates an image contrast related to the shear stiffness of soft tissue. MR-Touch is a single touch application that sensitively images the propagation characteristics of acoustic shear waves generated in the tissue of interest. A liver exam is an example of where the application is used.

MR-Touch is performed by synchronizing the Gradient Echo (1.5T pulse sequence used) used with acoustic waves that are applied with an external MR-Touch Device. The pulse sequence is modified with an oscillating Motion Encoding Gradient (MEG). The external acoustic driver is triggered by the PSD so that the MEG is synchronized with the external acoustic wave. The duration of the MEG is the same as the period of the mechanical vibration. A phase shift occurs in the MR signal, which correlates with the mechanical excursion. An algorithm is used to derive a relative stiffness map and wave images from the phase images.

MR-Touch acquisition generates the following image types: magnitude, phase maps, wave maps. Six relative stiffness images are reconstructed for each slice location. The relative stiffness images are reconstructed in color and grey scale, and in masked and un-masked versions. Mask portion is depicted as a checkerboard pattern on the image. It is created to identify regions that should not be included in ROI measurements.

Table 1. MR-Touch image maps
Image mapImage map
Figure 1. Anatomic/Magnitude image
Figure 2. Phase map: 4 phases
Figure 3. Grey Elastogram, no mask, scale 0-32767
Figure 4. Grey Elastogram, with mask, scale 0-32767
Figure 5. Color Elastogram, no mask, scale 0-8
Figure 6. Color Elastogram, with mask, scale 0-8
Figure 7. Color Elastogram, no mask, scale 0-20
Figure 8. Color Elastogram, with mask, scale 0-20
Figure 9. Color wave image: 4 phases
Figure 10. Attenuation