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High‐field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localization
Author(s) -
Near Jamie,
Romagnoli Cesare,
Curtis Andrew T.,
Klassen L. Martyn,
Izawa Jonathan,
Chin Joseph,
Bartha Robert
Publication year - 2009
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.21841
Subject(s) - electromagnetic coil , specific absorption rate , imaging phantom , voxel , adiabatic process , materials science , finite difference time domain method , nuclear magnetic resonance , prostate , optics , physics , computer science , radiology , telecommunications , medicine , cancer , quantum mechanics , antenna (radio) , thermodynamics
Purpose To demonstrate in vivo magnetic resonance spectroscopic imaging (MRSI) of the human prostate at 4.0T using a transmit/receive endorectal coil and a pulse sequence designed specifically for this application. Materials and Methods A solid, reusable endorectal probe was designed for both radiofrequency transmission and reception. Finite difference time domain (FDTD) simulations were performed to characterize the coil's electric field distribution, and temperature measurements were performed in a beef tissue phantom to determine the coil's safe operating limit. The localization by selective adiabatic refocusing (LASER) pulse sequence was implemented using six gradient modulated offset independent adiabatic (GOIA) pulses for very sharp, B 1 ‐insensitive voxel localization. Results Based on the simulations and temperature measurements, the coil's safe operating limit was conservatively estimated to be 1.0W for 15 minutes. The transition width of the GOIA pulse selection profiles was only 6% of the bandwidth, compared with 22% for a specific absorption rate (SAR)‐matched conventional adiabatic pulse. Using the coil and pulse sequence described here, MRSI data were successfully acquired from a patient with biopsy‐proven prostate cancer, with a nominal voxel size of 0.34 cc in a scan time of 15 minutes. Conclusion This work demonstrates the safe and effective use of a transmit/receive endorectal coil for in vivo MRSI of the prostate. J. Magn. Reson. Imaging 2009;30:335–343. © 2009 Wiley‐Liss, Inc.