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Towards Real-Time PRFS Thermometry Using Simultaneous MultiSlice Acquisitions

S Crijns

P Borman , S Crijns*, C Bos , C Moonen , B Raaymakers , University Medical Center Utrecht, Utrecht, Utrecht


SU-E-J-2 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall

To speed up PRFS thermometry using Simultaneous MultiSlice acquisitions (SMS) with a focus on HIFU treatments, where temperatures at multiple locations such as near field, far field and focus need to be monitored in real-time.

The phantom is a 2% agar 2% silica gel. The gel was heated using an ultrasound transducer operating at 1.2MHz with a focus of 8mm, delivering 60W for 60 seconds. The temperature is measured with two optical probes; one at the focus and one 4cm above that. The probes are used to compare the PRFS thermometry results with. The images are made on a 1.5T Philips Achieva scanner with a SMS GRE acquisition using CAIPIRINHA: two slices are excited simultaneously with a Multi-Band pulse and one slice is shifted one half FOV, resulting in minimal overlap and optimal sensitivity.
The images are reconstructed off-line in MATLAB using ReconFrame (GyroTools). The temperature is calculated from the PRFS and averaged over an ROI at the focus. The SMS acquisition has acceleration factor 2 and can be combined with SENSE. Results are compared to M2D acquisitions with SENSE factors 1 and 2.

The SMS temperature curves are in good qualitative agreement with the temperature curves of the probes. The difference is probably caused by the probes not being exactly at the focus. There is good agreement between the M2D and SMS curves, even though SMS scans have acceleration factor 2. We also showed that SMS can be combined with SENSE to achieve acceleration factor 3.

This work shows that PRFS thermometry in multiple slices can be accelerated by SMS techniques. We demonstrated that the temperature measured using SMS scans is in agreement with the M2D scans, while the dynamic scan time of the former is almost half of that of the latter.

Funding Support, Disclosures, and Conflict of Interest: This work was funded by the SoRTS consortium

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