High‐speed 3T MR spectroscopic imaging of prostate with flyback echo‐planar encoding

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 biopsyproven 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.

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“…This is in agreement with previous studies that have shown the highest citrate/choline ratios in the peripheral zone (2,24).…”

Section: Discussionsupporting

confidence: 94%

“…This linewidth increase was the result of a susceptibility artifact caused by the interfaces between the coil and the rectal wall, and between the rectal wall and the prostate. This artifact could be minimized by filling the probe with a susceptibility-matched fluid, as has been demonstrated previously (24).…”

Section: Discussionmentioning

confidence: 97%

High‐field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localization

Near

Romagnoli

Curtis

et al. 2009

Magnetic Resonance Imaging

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“…Imaging at 3T can also improve DTI and DCE imaging that can provide additional quantitative functional measures of the prostate at a higher spatial resolution than MRSI [44,46,47,60]. DCE MRI provides valuable information concerning prostate cancer microvascularity and angiogenesis [9][10][11][12][13][14][15].…”

Section: Multiparametric Mri At 3tmentioning

confidence: 99%

“…Vigorous progress still continues in the stillyoung science of prostate MRI, and in new, related imaging techniques such as magnetic resonance spectroscopic imaging (MRSI) [6], diffusion tensor imaging (DTI) [7,8], and dynamic contrast enhanced (DCE) imaging [9][10][11][12][13][14][15]. A number of recent MRI studies have demonstrated that the detection and characterization of prostate cancer can be improved through the addition of MRSI [16,17,18 • ,19, 20 • , 21 , 22 • , 23 [42][43][44], and by performing the imaging exam at 3T [45][46][47]. In this article, the current clinical status of these advanced imaging techniques for the detection and characterization of prostate cancer will be concisely reviewed with an emphasis on the clinical utility of the resulting imaging information.…”

Section: Introductionmentioning

confidence: 99%

Multiparametric magnetic resonance imaging in prostate cancer: present and future

Kurhanewicz

Vigneron

Carroll

et al. 2008

Current Opinion in Urology

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210

162

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Purpose of review-The purpose of this article is to review the current status of advanced MRI techniques based on anatomic, metabolic and physiologic properties of prostate cancer with a focus on their impact in managing prostate cancer patients.Recent findings-Prostate cancer can be identified based on reduced T 2 signal intensity on MRI, increased choline and decreased citrate and polyamines on magnetic resonance spectroscopic imaging (MRSI), decreased diffusivity on diffusion tensor imaging (DTI), and increased uptake on dynamic contrast enhanced (DCE) imaging. All can be obtained within a 60-min 3T magnetic resonance exam. Each complementary method has inherent advantages and disadvantages: T 2 MRI has high sensitivity but poor specificity; magnetic resonance spectroscopic imaging has high specificity but poor sensitivity; diffusion tensor imaging has high spatial resolution, is the fastest, but sensitivity/specificity needs to be established; dynamic contrast enhanced imaging has high spatial resolution, but requires a gadolinium based contrast agent injection, and sensitivity/specificity needs to be established.Summary-The best characterization of prostate cancer in individual patients will most likely result from a multiparametric (MRI/MRSI/DTI/DCE) exam using 3T magnetic resonance scanners but questions remain as to how to analyze and display this large amount of imaging data, and how to optimally combine the data for the most accurate assessment of prostate cancer. Histological correlations or clinical outcomes are required to determine sensitivity/specificity for each method and optimal combinations of these approaches.

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“…Therefore, another viewpoint emphasizes the spatial distribution of key metabolites, acquiring high-resolution k-space coverage with limited chemical-shift encoding echo-time values. Due to developments in gradient hardware and processing techniques, echo-planar imaging has become popular in magnetic resonance spectroscopic imaging [7] [8]. It provides rapid acquisition of the MRSI data set, recording one or more k-space frames in a single excitation.…”

Section: Introductionmentioning

confidence: 99%

Optimal echo-time selection for MRSI acquisition

Deng

Reeves

Twieg

2011

2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro

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Long acquisition time is one of the major challenges of magnetic resonance spectroscopic imaging (MRSI). Patient discomfort, motion artifacts and cost will increase when the acquisition time lengthens. In order to accelerate the data collecting process, we propose to apply sequential backward selection (SBS) to optimal echo-time selection and then use these selected echo-time values in echo-planar imaging (EPI) acquisition. For multi-echo EPI, our method allows multiple echo-time values to be selected simultaneously. As a result, in each excitation, multiple k-space frames can be acquired and the acquisition time reduces further. Phantom experiments demonstrate the feasibility of the proposed method. We compare the reconstructed spatial and spectral results from this new technique, standard MRSI, equal echo-time selection and random echo-time selection. Comparisons show that the proposed method can achieve similar results to standard MRSI while greatly reducing the data quantity requirements.

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High‐speed 3T MR spectroscopic imaging of prostate with flyback echo‐planar encoding

Cited by 46 publications

References 11 publications

High‐field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localization

High‐field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localization

Multiparametric magnetic resonance imaging in prostate cancer: present and future

Optimal echo-time selection for MRSI acquisition

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