A phase-cycled temperature-sensitive fast spin echo sequence with conductivity bias correction for monitoring of mild RF hyperthermia with PRFS.

Objective: Mild hyperthermia (HT) treatments are generally monitored by phase-referenced proton resonance frequency shift calculations. A novel phase and thus temperature-sensitive fast spin echo (TFSE) sequence is introduced and compared to the double echo gradient echo (DEGRE) sequence.

Theory And Methods: For a proton resonance frequency shift (PRFS)-sensitive TFSE sequence, a phase cycling method is applied to separate even from odd echoes.

Minimizing eddy currents induced in the ground plane of a large phased-array ultrasound applicator for echo-planar imaging-based MR thermometry.

Background: The study aims to investigate different ground plane segmentation designs of an ultrasound transducer to reduce gradient field induced eddy currents and the associated geometric distortion and temperature map errors in echo-planar imaging (EPI)-based MR thermometry in transcranial magnetic resonance (MR)-guided focused ultrasound (tcMRgFUS).

Methods: Six different ground plane segmentations were considered and the efficacy of each in suppressing eddy currents was investigated in silico and in operando. For the latter case, the segmented ground planes were implemented in a transducer mockup model for validation.

Effects of inner volume field-of-view reduction on myocardial T2 mapping.

Background: Inner volume (IV) excitation was explored with respect to scan time reduction of cardiac gated double inversion recovery multi-echo fast spin echo (MEFSE) to measure the transverse relaxation time (T2 ) in the myocardium.

Methods: The IV imaging was achieved by applying orthogonal slice selection for the excitation and refocusing pulses. The T2 map accuracy was investigated using different excitation and refocusing pulses.