Displacement correction scheme for MR-guided interstitial laser therapy

MR guided interstitial laser therapy can be used to monitor the extent of tumor tissue coagulation during thermal treatment based on a temperature map. In a non-stationary object that was influenced by respiratory motion, the temperature map may show errors due to incorrect spatial baseline images. Moreover, an unwanted phase shift due to object displacement contributes to errors in the temperature map, that must be suppressed. This paper describes a strategy which addresses the difficulties of MR guided interstitial laser therapy in the presence of respiratory motion. The multi-baseline images, supported by the displacement correction scheme, were used to improve the temporal resolution of a temperature map in the respiratory cycle. In the displacement correction scheme, the object coordinates that are provided by an active tracking coil were employed to support a matching strategy between the thermal and baseline images. To avoid errors in the temperature map due to the motion artifact, a detector of low quality images was proposed as part of the displacement correction scheme.