<sup>31</sup>P MR spectroscopic imaging combined with <sup>1</sup>H MR spectroscopic imaging in the human prostate using a double tuned endorectal coil at 7T

Luttje, Mariska; Italiaander, Michel; Castro, C. S. Arteaga de; Kemp, Wybe J. M. van der; Luijten, Peter R.; Vulpen, Marco van; Heide, Uulke A. van der; Klomp, Dennis W. J.

doi:10.1002/mrm.25070

Cited by 19 publications

(26 citation statements)

References 20 publications

(33 reference statements)

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“…The use of endorectal coils, which can further increase SNR at the cost of subject discomfort, is not treated in this article. Endorectal coils for 7T prostate imaging have been used . As the results in this study show, SNR is gained at 7T compared with 3T, especially in regions closer to the coil.…”

Section: Discussionmentioning

confidence: 89%

Comparing signal‐to‐noise ratio for prostate imaging at 7T and 3T

Steensma

Luttje

Voogt

et al. 2018

Magnetic Resonance Imaging

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Background In MRI, the signal‐to‐noise ratio (SNR) theoretically increases with B 0 field strength. However, because of attenuation of the radiofrequency (RF) fields at 7T, it is not certain if this SNR gain can be realized for prostate imaging. Purpose/Hypothesis To investigate the SNR gain in prostate imaging at 7T as compared with 3T. It is expected that SNR will improve for prostate imaging at 7T compared with 3T. Study Type Prospective. Subjects Four healthy volunteers and one prostate cancer patient. Field Strength/Sequence All subjects were scanned at 3T and at 7T using optimal coil setups for both field strengths. For all volunteers, proton density‐weighted images were acquired for SNR analysis and actual flip angle imaging (AFI) maps were acquired for correction of measured SNR values. In the patient, a T 2 ‐weighted (T 2 w) image was acquired at 3T and at 7T. Assessment SNR was calculated in the prostate region for all volunteers. SNR was normalized for flip angle, receiver bandwidth, and voxel volume. SNR was also calculated for different sensitivity encoding (SENSE) acceleration factors. Statistical Testing SNR values are represented as the arithmetic mean of SNR values in the prostate. Estimated SNR in the T 2 w image is calculated as the arithmetic mean of the signal intensity (SI) divided by the standard deviation of the SI in a specified zone. Tumor‐to‐tissue contrast is calculated as (SI tumor +SI zone )/( SI tumor ‐SI zone ). Results An increase in SNR ranging from 1.7‐fold to 2.8‐fold was measured in the prostate at 7T in comparison to 3T for four volunteers. At 7T, it is possible to achieve a 4‐fold SENSE acceleration in the left‐right direction with similar SNR to a nonaccelerated 3T image. T 2 w imaging was done at 3T and 7T in one patient, where improved tumor‐to‐tissue contrast was demonstrated at 7T. Data Conclusion SNR improves for prostate imaging at 7T as compared with 3T. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1446–1455.

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Section: Discussionmentioning

confidence: 89%

Comparing signal‐to‐noise ratio for prostate imaging at 7T and 3T

Steensma

Luttje

Voogt

et al. 2018

Magnetic Resonance Imaging

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“…Some limitations of MRI are that highfieldstrength MRI systems cur rently available are not configured for intraoperative imaging and surgical guidance, and their resolution is still limited to about 200 μm per voxel in plane and 2-3 mm in the z direction. Future trends in imaging of the prostate using MRI include the introduction of magnets with a higher field strength (for example, 7 T and greater) for continued improvement in sensitivity, resolution, and image acquisition times; [91][92][93][94] however, further safety studies are w arranted before increased field strengths should be used. …”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%

Novel methods for mapping the cavernous nerves during radical prostatectomy

Fried

Burnett

2015

Nat Rev Urol

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The cavernous nerves, which course along the surface of the prostate gland, are responsible for erectile function. During radical prostatectomy, urologists are challenged in preserving these nerves and their function. Cavernous nerves are microscopic and show variable location in different patients; therefore, postoperative sexual potency rates are widely variable following radical prostatectomy. A variety of technologies, including electrical and optical nerve stimulation, dye-based optical fluorescence and microscopy, spectroscopy, ultrasound and magnetic resonance imaging have all been used to study cavernous nerve anatomy and physiology, and some of these methods are also potential intraoperative methods for identifying and preserving cavernous nerves. However, all of these technologies have inherent limitations, including slow or inconsistent nerve responses, poor image resolution, shallow image depth, slow image acquisition times and/or safety concerns. New and emerging technologies, as well as multimodal approaches combining existing methods, hold promise for improved postoperative sexual outcomes and patient quality of life following radical prostatectomy.

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“…However, for T 2 W imaging and DWI of the prostate at 7T, only using an endorectal coil is inadequate. Transmitting radiofrequency pulses with a small local surface coil results in substantial transition bands in T 2 W and DWI images due to its severely inhomogeneous transmit profile . This can be solved by using a multichannel external body array in combination with B 1 + shimming to provide a homogeneous transmit field .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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Purpose In vivo 1H and 31P 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 1H and 31P spectroscopic imaging of the prostate using a 31P and 1H endorectal radiofrequency coil (ERC) in combination with a multitransmit body array at 7 Tesla (T).MethodsAn ERC with a 31P transceiver loop coil and 1H receive (Rx) asymmetric microstrip (31P/1H ERC) was designed, constructed and tested in combination with an external 8‐channel 1H 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 1H 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 1H and 31P spectroscopic imaging.ResultsElectromagnetic field simulations of the 31P loop coil showed no differences in the E‐ and B‐fields of the 31P/1H ERC compared with a previously safety validated ERC without 1H microstrip. The hotspot of the specific absorption rate (SAR) at the feed point of the 31P/1H ERC loop coil was 9.42 W/kg when transmitting on 31P at 1 W. Additional in vivo measurements showed a maximum temperature increase at the SAR hotspot of 0.7°C over 6 min on 31P at 1.9 W transmit (Tx) power, indicating safe maximum power levels. When transmitting with the external 1H 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 1H microstrip of the ERC provided higher SNR than the 8CH. The total coil combination allowed acquisition of an mpMRI protocol and the assessment of 31P and 1H metabolites of the prostate in all test subjects.ConclusionWe developed a setup with a 31P transceiver and 1H 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 1H and 31P MRSI at 7T in patients with prostate cancer within one MR examination.

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³¹P MR spectroscopic imaging combined with ¹H MR spectroscopic imaging in the human prostate using a double tuned endorectal coil at 7T

Abstract: (1) H MRSI and (31) P MRSI can be acquired in the human prostate at 7T within the same scan session using an endorectal coil matched and tuned for (1) H (quadrature) and (31) P (linear) without the need of cable traps and with negligible efficiency losses in the (1) H and (31) P channel.

Cited by 19 publications

References 20 publications

Comparing signal‐to‐noise ratio for prostate imaging at 7T and 3T

Comparing signal‐to‐noise ratio for prostate imaging at 7T and 3T

Novel methods for mapping the cavernous nerves during radical prostatectomy

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

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31P MR spectroscopic imaging combined with 1H MR spectroscopic imaging in the human prostate using a double tuned endorectal coil at 7T

Abstract: (1) H MRSI and (31) P MRSI can be acquired in the human prostate at 7T within the same scan session using an endorectal coil matched and tuned for (1) H (quadrature) and (31) P (linear) without the need of cable traps and with negligible efficiency losses in the (1) H and (31) P channel.

Cited by 19 publications

References 20 publications

Comparing signal‐to‐noise ratio for prostate imaging at 7T and 3T

Comparing signal‐to‐noise ratio for prostate imaging at 7T and 3T

Novel methods for mapping the cavernous nerves during radical prostatectomy

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

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³¹P MR spectroscopic imaging combined with ¹H MR spectroscopic imaging in the human prostate using a double tuned endorectal coil at 7T

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