Dataset Information

Development and evaluation of a multichannel endorectal RF coil for prostate MRI at 7T in combination with an external surface array.

ABSTRACT: To develop and evaluate a sterilizable multichannel endorectal coil (ERC) for use in combination with an external surface array (ESA) for high-resolution anatomical and functional studies of the prostate at 7T.A two-loop ERC (ERC-2L) and a microstrip-loop ERC (ERC-ML) were compared at 7T in terms of transmit and receive performance. The best-performing ERC was evaluated alone and in combination with the ESA through 1) simulations on both phantom and an anatomically correct numerical human model to assess B1+ transmit and specific absorption rate (SAR) efficiencies, and 2) phantom experiments to calculate B1+ transmit efficiency and signal-to-noise ratio (SNR). Phantom studies were also performed to look at heating when using the ERC as a transmitter and for comparing the new coil against a single-channel balloon-type ERC (ERC-b). High-resolution magnetic resonance imaging (MRI) acquisitions were performed on a single healthy subject using the two-channel ERC combined with the ESA.Compared to the ERC-ML, the ERC-2L demonstrated 20% higher SAR efficiency and higher SNR 3?cm from the coil. The presence of a tuned and detuned ERC-2L did not alter the peak local SAR of the ESA alone; however, the detuned ERC-2L had 45% less peak local SAR around the rectum compared to the tuned ERC-2L. The receive-only version of the ERC-2L improved the SNR 4.7-fold and 1.3-fold compared to the ESA and ERC-b, respectively. In combination with the ESA, the ERC-2L supported in-plane voxel-size of 0.36 × 0.36?mm(2) in T2 -weighted anatomic imaging.The reusable ERC-2L combined with an ESA offers a high SNR imaging platform for translational studies of the prostate at 7T. J. Magn. Reson. Imaging 2016;43:1279-1287.

SUBMITTER: Erturk MA

PROVIDER: S-EPMC4865450 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Development and evaluation of a multichannel endorectal RF coil for prostate MRI at 7T in combination with an external surface array.

Ertürk M Arcan MA Tian Jinfeng J Van de Moortele Pierre-François PF Adriany Gregor G Metzger Gregory J GJ

Journal of magnetic resonance imaging : JMRI 20151119 6

<h4>Purpose</h4>To develop and evaluate a sterilizable multichannel endorectal coil (ERC) for use in combination with an external surface array (ESA) for high-resolution anatomical and functional studies of the prostate at 7T.<h4>Materials and methods</h4>A two-loop ERC (ERC-2L) and a microstrip-loop ERC (ERC-ML) were compared at 7T in terms of transmit and receive performance. The best-performing ERC was evaluated alone and in combination with the ESA through 1) simulations on both phantom and ...[more]

PMID: 26584144

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Project description: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.

Dataset Information

Development and evaluation of a multichannel endorectal RF coil for prostate MRI at 7T in combination with an external surface array.

Publications

Development and evaluation of a multichannel endorectal RF coil for prostate MRI at 7T in combination with an external surface array.

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