MR-Cavitation Dynamics Encoded (MR-CaDE) imaging

Area of Science:

• Medical Imaging
• Neurosurgery
• Acoustic Physics

Background:

• Histotripsy is a non-invasive mechanical ablation technique using focused ultrasound.
• Monitoring cavitation dynamics is crucial for optimizing histotripsy treatments.
• Existing methods lack the real-time feedback needed for precise brain interventions.

Purpose of the Study:

• To develop and validate MR-Cavitation Dynamics Encoded (MR-CaDE) imaging for dynamic cavitation monitoring.
• To assess the feasibility of MR-CaDE for real-time histotripsy treatment monitoring in the brain.
• To test the technique in an ex-vivo human brain model within a clinical MRI scanner.

Main Methods:

• Modified a Gradient Echo (GRE) pulse sequence with bipolar gradients to create MR-CaDE imaging.
• Monitored histotripsy-induced cavitation in ex-vivo bovine brain tissue using MR-CaDE on a 3T MRI scanner.
• Utilized a 0.5s temporal resolution with a spiral readout and synchronized MR acquisition with histotripsy pulses.

Main Results:

• MR-CaDE successfully visualized cavitation dynamics, showing decreased image magnitude and increased phase with increasing sonications.
• Observed a peak magnitude loss of 50% and a maximum phase increase of 0.64rad.
• Post-histotripsy lesions showed good alignment with MR-CaDE signal changes, with minimal spatial error.

Conclusions:

• Demonstrated the feasibility of the MR-CaDE pulse sequence for monitoring cavitation.
• The developed method shows promise for real-time feedback during histotripsy treatments in the brain.
• MR-CaDE enables dynamic cavitation monitoring, enhancing precision in ultrasound-guided neurosurgery.