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A multitransmit external body array combined with a 1 H and 31 P endorectal coil to enable a multiparametric and multimetabolic MRI examination of the prostate at 7T.


ABSTRACT: PURPOSE:In vivo 1 H and 31 P magnetic resonance spectroscopic imaging (MRSI) provide complementary information on the biology of prostate cancer. In this work we demonstrate the feasibility of performing multiparametric imaging (mpMRI) and 1 H and 31 P spectroscopic imaging of the prostate using a 31 P and 1 H endorectal radiofrequency coil (ERC) in combination with a multitransmit body array at 7 Tesla (T). METHODS:An ERC with a 31 P transceiver loop coil and 1 H receive (Rx) asymmetric microstrip (31 P/1 H ERC) was designed, constructed and tested in combination with an external 8-channel 1 H transceiver body array coil (8CH). Electromagnetic field simulations and measurements and in vivo temperature measurements of the ERC were performed for safety validation. In addition, the signal-to-noise (SNR) benefit of the 1 H microstrip with respect to the 8CH was evaluated. Finally, the feasibility of the setup was tested in one volunteer and three patients with prostate cancer by performing T2 -weighted and diffusion-weighted imaging in combination with 1 H and 31 P spectroscopic imaging. RESULTS:Electromagnetic field simulations of the 31 P loop coil showed no differences in the E- and B-fields of the 31 P/1 H ERC compared with a previously safety validated ERC without 1 H microstrip. The hotspot of the specific absorption rate (SAR) at the feed point of the 31 P/1 H ERC loop coil was 9.42 W/kg when transmitting on 31 P at 1 W. Additional in vivo measurements showed a maximum temperature increase at the SAR hotspot of 0.7°C over 6 min on 31 P at 1.9 W transmit (Tx) power, indicating safe maximum power levels. When transmitting with the external 1 H body array at 40W for 2:30 min, the temperature increase around the ERC was < 0.3°C. Up to 3.5 cm into the prostate the 1 H microstrip of the ERC provided higher SNR than the 8CH. The total coil combination allowed acquisition of an mpMRI protocol and the assessment of 31 P and 1 H metabolites of the prostate in all test subjects. CONCLUSION:We developed a setup with a 31 P transceiver and 1 H Rx endorectal coil in combination with an 8-channel transceiver external body array coil and demonstrated its safety and feasibility for obtaining multiparametric imaging and 1 H and 31 P MRSI at 7T in patients with prostate cancer within one MR examination.

SUBMITTER: Philips BWJ 

PROVIDER: S-EPMC6852321 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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A multitransmit external body array combined with a <sup>1</sup> H and <sup>31</sup> P endorectal coil to enable a multiparametric and multimetabolic MRI examination of the prostate at 7T.

Philips Bart W J BWJ   van Uden Mark J MJ   Rietsch Stefan H G SHG   Orzada Stephan S   Scheenen Tom W J TWJ  

Medical physics 20190801 9


<h4>Purpose</h4>In vivo <sup>1</sup> H and <sup>31</sup> P magnetic resonance spectroscopic imaging (MRSI) provide complementary information on the biology of prostate cancer. In this work we demonstrate the feasibility of performing multiparametric imaging (mpMRI) and <sup>1</sup> H and <sup>31</sup> P spectroscopic imaging of the prostate using a <sup>31</sup> P and <sup>1</sup> H endorectal radiofrequency coil (ERC) in combination with a multitransmit body array at 7 Tesla (T).<h4>Methods</h4  ...[more]

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2016-06-07 | GSE80683 | GEO