Systems and methods for magnetic resonance based skull thermometry

A method for magnetic resonance (MR) based thermometry, comprising:

• acquiring, by a variable flip-angle (VFA) T1 mapping sequence, MR data in an area of interest of a subject corresponding to cortical bone of at least part of a skull of a subject that is heated by application of focused ultrasound (FUS) to a selective portion of a brain of the subject,
• wherein the MR data comprises a plurality of T1 values over time that include a first point in time and a later, second point in time, and wherein the acquisition of the MR data comprises obtaining dual echo MR data by applying an accelerated three-dimensional (3D) ultra-short (UTE) spiral acquisition sequence with a nonselective excitation pulse and an echo time of 100 microseconds or less;
• achieving a selected temporal resolution by applying Low-Rank Plus Sparse Matrix Decomposition to the dual echo MR data;
• calculating a corresponding temperature change in the cortical bone by tracking changes in a proton resonance frequency (PRF) during the application of the focused ultrasound (FUS);
• determining, based at least in part on a mathematical relationship established by T1 mapping thermometry produced according to the VFA T1 mapping sequence and the changes in the proton resonance frequency (PRF), a temperature change in the cortical bone that occurs between the first point in time and the second point in time, and wherein the temperature change is caused at least in part by a change in the application of FUS.

A method for magnetic resonance (MR) based thermometry, comprising:

• acquiring, by a variable flip-angle (VFA) T1 mapping sequence, MR data in an area of interest of a subject corresponding to cortical bone of at least part of a skull of a subject that is heated by application of focused ultrasound (FUS) to a selective portion of a brain of the subject,
• wherein the MR data comprises a plurality of T1 values over time that include a first point in time and a later, second point in time, and wherein the acquisition of the MR data comprises obtaining dual echo MR data by applying an acquisition weighted stack of spirals;
• achieving a selected temporal resolution by applying variable duration slice encoding to the MR data;
• calculating a corresponding temperature change in the cortical bone by tracking changes in a proton resonance frequency (PRF) during the application of the focused ultrasound (FUS);
• determining, based at least in part on a mathematical relationship established by T1 mapping thermometry produced according to the VFA T1 mapping sequence and the changes in the proton resonance frequency (PRF), a temperature change in the cortical bone that occurs between the first point in time and the second point in time, and wherein the temperature change is caused at least in part by a change in the application of FUS.