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Gambarota G. Optimization of metabolite detection by quantum mechanics simulations in magnetic resonance spectroscopy. Anal Biochem 2017; 529:65-78. [DOI: 10.1016/j.ab.2016.08.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 07/31/2016] [Accepted: 08/22/2016] [Indexed: 10/21/2022]
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Ratai EM, Gilberto González R. Clinical magnetic resonance spectroscopy of the central nervous system. HANDBOOK OF CLINICAL NEUROLOGY 2016; 135:93-116. [PMID: 27432661 DOI: 10.1016/b978-0-444-53485-9.00005-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Proton magnetic resonance spectroscopy (1H MRS) is a noninvasive imaging technique that can easily be added to the conventional magnetic resonance (MR) imaging sequences. Using MRS one can directly compare spectra from pathologic or abnormal tissue and normal tissue. Metabolic changes arising from pathology that can be visualized by MRS may not be apparent from anatomy that can be visualized by conventional MR imaging. In addition, metabolic changes may precede anatomic changes. Thus, MRS is used for diagnostics, to observe disease progression, monitor therapeutic treatments, and to understand the pathogenesis of diseases. MRS may have an important impact on patient management. The purpose of this chapter is to provide practical guidance in the clinical application of MRS of the brain. This chapter provides an overview of MRS-detectable metabolites and their significance. In addition some specific current clinical applications of MRS will be discussed, including brain tumors, inborn errors of metabolism, leukodystrophies, ischemia, epilepsy, and neurodegenerative diseases. The chapter concludes with technical considerations and challenges of clinical MRS.
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Affiliation(s)
- Eva-Maria Ratai
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, and Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, USA.
| | - R Gilberto González
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, and Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, USA
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Ma C, Chen L, Scheenen TWJ, Lu J, Wang J. Three-dimensional proton magnetic resonance spectroscopic imaging with and without an endorectal coil: a prostate phantom study. Acta Radiol 2015; 56:1342-9. [PMID: 25348479 DOI: 10.1177/0284185114556704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 09/25/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND Proton magnetic resonance spectroscopic imaging (MRSI) of the prostate has been used with only a combination of external surface coils. The quality of spectral fitting of the (choline + creatine)/citrate ([Cho + Cr]/Cit) ratio at different field strengths and different coils is important for quantitative/semi-quantitative diagnosis of prostate cancer. PURPOSE To evaluate the quality of spectral fitting of the (Cho + Cr)/Cit ratio of a prostate phantom using MRSI at different field strengths and various coils. MATERIAL AND METHODS Experiments were using 1.5-T and 3.0-T MR systems. Measurements were taken on a homemade prostate phantom with different coils: spinal array; abdominal array; and endorectal. The signal-to-noise ratio (SNR) of choline, creatine, and citrate peaks as well as the (Cho + Cr)/Cit ratio in each voxel were compared among groups using multi-way analysis of variance. RESULTS Magnetic field strength, coils, and plane position had a significant effect on the SNR or (Cho + Cr)/Cit ratio, and there were interactions among groups (all P = 0.000). The 1.5-T (0.228 ± 0.044) exhibited a higher (Cho + Cr)/Cit ratio than the 3.0-T (0.125 ± 0.041) magnetic field strength (F = 3238, P = 0.000). The (Cho + Cr)/Cit ratio of both surface coils (0.183 ± 0.065) and all coils (0.181 ± 0.057) was significantly lower than that of the endorectal coil (0.195 ± 0.077) (both P < 0.05), but significant differences in the mean (Cho + Cr)/Cit ratio were not observed if surface coils and all coils were used (P > 0.05). No significant differences were found among the (Cho + Cr)/Cit ratios of all voxels in the middle planes by the post-hoc analyses (all P > 0.05). CONCLUSION Three-dimensional proton MRSI of prostate metabolites in a phantom using surface coils is feasible and reliable, but (Cho + Cr)/Cit ratios acquired at different magnetic fields and coils were different. This difference should be taken into account when calculating this ratio in a field strength-independent way.
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Affiliation(s)
- Chao Ma
- Department of Radiology, Changhai Hospital of Shanghai, the Second Military Medical University, Shanghai, PR China
| | - Luguang Chen
- Department of Radiology, Changhai Hospital of Shanghai, the Second Military Medical University, Shanghai, PR China
| | - Tom WJ Scheenen
- Department of Radiology, Radboud University Medical Centre, Nijmegen, Gelderland, The Netherlands
| | - Jianping Lu
- Department of Radiology, Changhai Hospital of Shanghai, the Second Military Medical University, Shanghai, PR China
| | - Jian Wang
- Department of Radiology, Changhai Hospital of Shanghai, the Second Military Medical University, Shanghai, PR China
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Kobus T, Wright AJ, Weiland E, Heerschap A, Scheenen TWJ. Metabolite ratios in 1H MR spectroscopic imaging of the prostate. Magn Reson Med 2014; 73:1-12. [PMID: 24488656 DOI: 10.1002/mrm.25122] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/18/2013] [Accepted: 12/17/2013] [Indexed: 12/24/2022]
Abstract
In (1)H MR spectroscopic imaging ((1)H-MRSI) of the prostate the spatial distribution of the signal levels of the metabolites choline, creatine, polyamines, and citrate are assessed. The ratio of choline (plus spermine as the main polyamine) plus creatine over citrate [(Cho+(Spm+)Cr)/Cit] is derived from these metabolites and is used as a marker for the presence of prostate cancer. In this review, the factors that are of importance for the metabolite ratio are discussed. This is relevant, because the appearance of the metabolites in the spectrum depends not only on the underlying anatomy, metabolism, and physiology of the tissue, but also on acquisition parameters. These parameters influence especially the spectral shapes of citrate and spermine resonances, and consequently, the (Cho+(Spm+)Cr)/Cit ratio. Both qualitative and quantitative approaches can be used for the evaluation of (1)H-MRSI spectra of the prostate. For the quantitative approach, the (Cho+(Spm+)Cr)/Cit ratio can be determined by integration or by a fit based on model signals. Using the latter, the influence of the acquisition parameters on citrate can be taken into account. The strong overlap between the choline, creatine, and spermine resonances complicates fitting of the individual metabolites. This overlap and (unknown, possibly tissue-related) variations in T1, T2, and J-modulation hamper the application of corrections needed for a "normalized" (Cho+(Spm+)Cr)/Cit ratio that would enable comparison of spectra measured with different prostate MR spectroscopy protocols. Quantitative (Cho+(Spm+)Cr)/Cit thresholds for the evaluation of prostate cancer are therefore commonly established per institution or per protocol. However, if the same acquisition and postprocessing protocol were used, the ratio and the thresholds would be institution-independent, promoting the clinical usability of prostate (1)H-MRSI.
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Affiliation(s)
- Thiele Kobus
- Radboud University Medical Centre, Radiology Department, Nijmegen, The Netherlands
| | - Alan J Wright
- Radboud University Medical Centre, Radiology Department, Nijmegen, The Netherlands
| | | | - Arend Heerschap
- Radboud University Medical Centre, Radiology Department, Nijmegen, The Netherlands
| | - Tom W J Scheenen
- Radboud University Medical Centre, Radiology Department, Nijmegen, The Netherlands
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Kobus T, Wright AJ, Scheenen TWJ, Heerschap A. Mapping of prostate cancer by 1H MRSI. NMR IN BIOMEDICINE 2014; 27:39-52. [PMID: 23761200 DOI: 10.1002/nbm.2973] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/08/2013] [Accepted: 04/13/2013] [Indexed: 06/02/2023]
Abstract
In many studies, it has been demonstrated that (1)H MRSI of the human prostate has great potential to aid prostate cancer management, e.g. in the detection and localisation of cancer foci in the prostate or in the assessment of its aggressiveness. It is particularly powerful in combination with T2 -weighted MRI. Nevertheless, the technique is currently mainly used in a research setting. This review provides an overview of the state-of-the-art of three-dimensional MRSI, including the specific hardware required, dedicated data acquisition sequences and information on the spectral content with background on the MR-visible metabolites. In clinical practice, it is important that relevant MRSI results become available rapidly, reliably and in an easy digestible way. However, this functionality is currently not fully available for prostate MRSI, which is a major obstacle for routine use by inexperienced clinicians. Routine use requires more automation in the processing of raw data than is currently available. Therefore, we pay specific attention in this review on the status and prospects of the automated handling of prostate MRSI data, including quality control. The clinical potential of three-dimensional MRSI of the prostate is illustrated with literature examples on prostate cancer detection, its localisation in the prostate, its role in the assessment of cancer aggressiveness and in the selection and monitoring of therapy.
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Affiliation(s)
- Thiele Kobus
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
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Gambarota G, Bondon A, Le Floch M, Mulkern RV, Saint-Jalmes H. Selective spectral modulation of strongly coupled spins with an echo top refocusing pulse in PRESS sequences. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 228:76-80. [PMID: 23357429 DOI: 10.1016/j.jmr.2012.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 06/01/2023]
Abstract
The double spin echo is the basis of the point resolved spectroscopy (PRESS) sequence. In this study we sought to investigate the effects of a broadband 180° pulse - incorporated in the PRESS sequence at the location of the first echo (gPRESS) - on the citrate resonances, chosen as a model of strongly coupled spin system. A significant signal modulation generated by the additional 180° pulse was predicted with simulations and observed experimentally in the citrate resonances. No effects were observed on the singlet resonance of glycine and the weakly coupled resonances of lactate. The phenomenon observed in gPRESS was attributed to the off-diagonal Hamiltonian elements responsible for a coherence transfer occurring throughout the evolution periods. The results of this study show that it is necessary to assess the effects of broadband 180° pulses on strongly coupled spin systems, since these pulses can selectively modify the spectral shape of strongly coupled resonances.
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Yoshizako T, Uchida K, Hara S, Kaji Y, Sumura M, Igawa M, Kitagaki H, Uike M, Matsuda T. Prostate 3T-MR spectroscopic imaging without an endorectal surface coil using the MLEV-PRESS sequence. Jpn J Radiol 2012. [PMID: 23207646 DOI: 10.1007/s11604-012-0165-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE The aim of this study was to determine to what extent we could identify the metabolism product peak using 3-T proton magnetic resonance spectroscopic imaging (MRSI) of the prostate gland in healthy volunteers by combining an external array coil with Malcolm Levitt composite-pulse decoupling sequence (MLEV)-point-resolved spatially localized spectroscopy (PRESS). MATERIALS AND METHODS MRSI data were obtained from the entire prostate gland in six healthy volunteers. The heights of the choline, citrate peaks and the standard deviation (SD) of the noise in each voxel were calculated. When the choline and/or citrate peak in a voxel exceeded 3 SD, the peak was clearly identified. RESULTS The clear citrate peak rate in the peripheral zone (PZ) and the central gland (CG) were 78.8 and 70.3 %, respectively. The clear choline peak rate in the PZ and the CG were 55.4 and 44.9 %, respectively. In addition, the clear peak rates for both citrate and choline in the PZ and the CG were 51.8 and 38.6 %. Therefore, in the entire prostate gland, 75.2 % had a clear citrate peak, 51.1 % had a clear choline peak, and 46.3 % had both citrate and choline peaks. CONCLUSION The citrate peak was clearly detected in 75.2 % of the voxels by this technique.
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Affiliation(s)
- Takeshi Yoshizako
- Department of Radiology, Shimane University Faculty of Medicine, 89-1 Enya, P.O. Box 00693-8501, Izumo, Japan.
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Furuyama JK, Wilson NE, Burns BL, Nagarajan R, Margolis DJ, Thomas MA. Application of compressed sensing to multidimensional spectroscopic imaging in human prostate. Magn Reson Med 2012; 67:1499-505. [PMID: 22505247 DOI: 10.1002/mrm.24265] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/27/2012] [Accepted: 02/28/2012] [Indexed: 11/07/2022]
Abstract
The application of compressed sensing is demonstrated in a recently implemented four-dimensional echo-planar based J-resolved spectroscopic imaging sequence combining two spatial and two spectral dimensions. The echo-planar readout simultaneously acquires one spectral and one spatial dimension. Therefore, the compressed sensing undersampling is performed along the indirectly acquired spatial and spectral dimensions, and the reconstruction is performed using the split Bregman algorithm, an efficient TV-minimization solver. The four-dimensional echo-planar-based J-resolved spectroscopic imaging data acquired in a prostate phantom containing metabolites at physiological concentrations are accurately reconstructed with as little as 20% of the original data. Experimental data acquired in six healthy prostates using the external body matrix "receive" coil on a 3T magnetic resonance imaging scanner are reconstructed with acquisitions using only 25% of the Nyquist-Shannon required amount of data, indicating the potential for a 4-fold acceleration factor in vivo, bringing the required scan time for multidimensional magnetic resonance spectroscopic imaging within clinical feasibility.
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Affiliation(s)
- Jon K Furuyama
- Department of Radiological Sciences, University of California, Los Angeles, California 90095, USA
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Venugopal N, McCurdy B, Al Mehairi S, Alamri A, Sandhu GS, Sivalingam S, Drachenberg D, Ryner L. Short echo time in vivo prostate 1H-MRSI. Magn Reson Imaging 2012; 30:195-204. [DOI: 10.1016/j.mri.2011.09.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 07/28/2011] [Accepted: 09/18/2011] [Indexed: 10/14/2022]
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Nagarajan R, Gomez AM, Raman SS, Margolis DJ, McClure T, Thomas MA. Correlation of endorectal 2D JPRESS findings with pathological Gleason scores in prostate cancer patients. NMR IN BIOMEDICINE 2010; 23:257-261. [PMID: 19795373 DOI: 10.1002/nbm.1446] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To determine the metabolite ratios of (Cho + Cr)/Cit and (Cho + Cr)/Spm in patients with two ranges of pathological Gleason scores, namely (3 + 4) and (4 + 3). By using the localized two-dimensional (2D) J-resolved spectroscopy (JPRESS) technique, the metabolites ratios can be calculated and correlated with prostate cancer aggressiveness. A total of 24 patients who underwent endorectal 2D JPRESS between April 2006 and July 2007 were included in this study. The 2D JPRESS voxel was localized predominantly in the peripheral zone suspected for malignancy based on pathology. Using the metabolites such as total choline (Cho), creatine (Cr), spermine (Spm) and citrate (Cit), the ratios (Cho + Cr)/Cit and (Cho + Cr)/Spm were calculated. In 14 prostate cancer patients who had a final pathologic Gleason scores of i) (3 + 4 = 7, n = 7) and ii) (4 + 3 = 7, n = 7), the metabolite ratios (mean +/- SD) of (Cho + Cr)/Cit and (Cho + Cr)/Spm were calculated using the 2D JPRESS spectra as follows: i) (1.48 +/- 0.83) and (1.59 +/- 0.73); ii) (2.90 +/- 0.94) and (2.71 +/- 1.47), respectively. Higher percentage of aggressive disease correlates with higher metabolites ratio. Our pilot study suggests that 2D JPRESS can be reliably evaluated in a clinical setting using an endorectal coil. In addition to the citrate ratio, the spermine ratio also correlates with pathology based Gleason score.
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Affiliation(s)
- Rajakumar Nagarajan
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Snyder J, Thompson RB, Wilman AH. Difference spectroscopy using PRESS asymmetry: application to glutamate, glutamine, and myo-inositol. NMR IN BIOMEDICINE 2010; 23:41-47. [PMID: 19688783 DOI: 10.1002/nbm.1424] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A simple, clinically viable technique utilizing PRESS and strong coupling properties is presented for discrimination of coupled brain metabolites. The method relies on signal variation due to alteration of inter-echo timings (PRESS asymmetry) while maintaining a constant total echo time. Spin response of singlets and weakly coupled spins is unchanged due to PRESS asymmetry, allowing difference spectroscopy to detect unobstructed strongly coupled resonances. No changes to the standard PRESS sequence are required except variation of inter-echo timings. The procedure is illustrated for the separate detection of glutamate from glutamine and the detection of myo-inositol in simulation, phantom, and in vivo experiments at 4.7 T. The subtraction yields calculated from the simulation were 53% for glutamate and 75% for myo-inositol, and a resultant contribution of 96% glutamate to the total glutamate/glutamine multiplet in the 2.04-2.14 ppm range. To extend the treatment to other field strengths and metabolites, an analytical approximation based on a strongly coupled AB system was used to model individual spin groups. Subtraction spectroscopy yields for different combinations of coupling parameters were calculated for the detection of various strongly coupled metabolites at common clinical field strengths. The approximation also predicts adequate glutamate/glutamine discrimination at 3.0 T using the difference spectroscopy method.
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Affiliation(s)
- Jeff Snyder
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada
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Diffusion-weighted imaging with apparent diffusion coefficient mapping and spectroscopy in prostate cancer. Top Magn Reson Imaging 2009; 19:261-72. [PMID: 19512848 DOI: 10.1097/rmr.0b013e3181aa6b50] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Prostate cancer is a major health problem, and the exploration of noninvasive imaging methods that have the potential to improve specificity while maintaining high sensitivity is still critically needed. Tissue changes induced by tumor growth can be visualized by magnetic resonance imaging (MRI) methods. Current MRI methods include conventional T2-weighted imaging, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping and magnetic resonance spectroscopy (MRS). Techniques such as DWI/ADC provide functional information about the behavior of water molecules in tissue; MRS can provide biochemical information about the presence or absence of certain metabolites, such as choline, creatine, and citrate. Finally, vascular parameters can be investigated using dynamic contrast-enhanced MRI. Moreover, with whole-body MRI and DWI, metastatic disease can be evaluated in 1 session and may provide a way to monitor treatment. Therefore, when combining these various methods, a multiparametric data set can be built to assist in the detection, localization, assessment of prostate cancer aggressiveness, and tumor staging. Such a comprehensive approach offers more power to evaluate prostate disease than any single measure alone. In this article, we focus on the role of DWI/ADC and MRS in the detection and characterization using both in vivo and ex vivo imaging of prostate pathology.
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Near J, Romagnoli C, Bartha R. Reduced power magnetic resonance spectroscopic imaging of the prostate at 4.0 Tesla. Magn Reson Med 2009; 61:273-81. [PMID: 19165876 DOI: 10.1002/mrm.21845] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Proton magnetic resonance spectroscopic imaging (MRSI) of the prostate has been described at 1.5 T and 3 T as a means of localizing prostate cancers with high sensitivity and specificity. This technique could be improved by increasing the field strength further; however, it has not been described in detail above 3 T. To address the increase in B1 and SAR at high field strengths, a new protocol is described for reduced power STEAM MRSI of the prostate at 4.0 Tesla, using a pelvic surface coil array for RF transmission and reception, and a solid, reusable endorectal coil for reception only. The optimal STEAM sequence timing parameters for observation of the strongly coupled citrate spin system were determined through simulation to be echo time (TE) = 27 ms and mixing time (TM) = 27 ms, and the results were verified in vitro. Power reduction was achieved by applying the VERSE method to each of the three slice selective pulses in the STEAM sequence, and the B(1)max and SAR were reduced by 43% and 36%, respectively. Finally, in vivo spectroscopic imaging data were acquired from a prostate cancer patient, demonstrating the detection of citrate, choline, and creatine with 0.37 cc nominal resolution in a 10 minute scan.
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Affiliation(s)
- Jamie Near
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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Thomas MA, Lange T, Velan SS, Nagarajan R, Raman S, Gomez A, Margolis D, Swart S, Raylman RR, Schulte RF, Boesiger P. Two-dimensional MR spectroscopy of healthy and cancerous prostates in vivo. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2008; 21:443-58. [PMID: 18633659 DOI: 10.1007/s10334-008-0121-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 06/13/2008] [Accepted: 06/19/2008] [Indexed: 12/23/2022]
Abstract
OBJECTIVES A major goal of this article is to summarize the current status of evaluating prostate metabolites non-invasively using spatially resolved two-dimensional (2D) MR Spectroscopy (MRS). MATERIALS AND METHODS Due to various technical challenges, the spatially resolved versions of 2D MRS techniques are currently going through the developmental stage. During the last decade, four different versions of 2D MRS sequences have been successfully implemented on 3T and 1.5T MRI scanners manufactured by three different vendors. These sequences include half and maximum echo sampled J-resolved spectroscopy (JPRESS), S-PRESS and L-COSY, which are single volume localizing sequences, and the multi-voxel based JPRESS sequence. RESULTS Even though greater than 1ml voxels have been used, preliminary evaluations of 2D JPRESS, S-PRESS and L-COSY sequences have demonstrated unambiguous detection of citrate, creatine, choline, spermine and more metabolites in human prostates. ProFIT-based quantitation of JPRESS and L-COSY data clearly shows the superiority of 2D MRS over conventional one-dimensional (1D) MRS and more than six metabolites have been successfully quantified. These sequences have been evaluated in a small group of prostate pathologies and pilot investigations using these sequences show promising results in prostate pathologies. CONCLUSION Implementation of the state-of-the-art 2D MRS techniques and preliminary evaluation in prostate pathologies are discussed in this review. Even though these techniques are going through developmental and early testing phases, it is evident that 2D MRS can be easily added on to any clinical Magnetic Resonance Imaging (MRI) protocol to non-invasively record the biochemical contents of the prostate.
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Affiliation(s)
- M Albert Thomas
- Department of Radiological Sciences, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095-1721, USA.
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Abstract
More recently, 3-T magnetic resonance (MR) scanner become more clinically available, and clinical application of 3-T MR imaging (MRI) of the abdomen and pelvis is now feasible and being performed at many institutions. However, few prostrate 3-T MRI studies have been published. The increase in signal-to-noise ratio at 3 versus 1.5 T clearly improves spatiotemporal and spectral resolutions of the prostate. Thus, we asked whether 3-T MRI improves the localization and staging of prostate cancer versus 1.5-T MRI. To answer this question, this article reviews the current limitations of prostate 1.5-T MRI and addresses its pros and cons. Moreover, we present preliminary results of prostate 3-T MRI and introduce our experience for prostate 3-T MRI using a phased-array coil, with an emphasis on imaging sequences, for example, T2-weighted, dynamic contrast-enhanced, diffusion-weighted, and MR spectroscopic imaging.
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Scheenen TWJ, Heijmink SWTPJ, Roell SA, Hulsbergen-Van de Kaa CA, Knipscheer BC, Witjes JA, Barentsz JO, Heerschap A. Three-dimensional Proton MR Spectroscopy of Human Prostate at 3 T without Endorectal Coil: Feasibility. Radiology 2007; 245:507-16. [PMID: 17848681 DOI: 10.1148/radiol.2451061444] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
PURPOSE To evaluate sensitivity and specificity of proton magnetic resonance (MR) spectroscopy of the prostate with external surface coil elements at 3 T for differentiation of cancer from healthy tissue within an acceptable measurement time, by using histopathologic findings as the reference standard. MATERIALS AND METHODS The study was approved by the institutional review board; informed consent was obtained. Forty-five men (age range, 51-70 years) underwent 3-T MR imaging with external radiofrequency surface coils for signal reception. MR spectroscopy was performed with acquisition-weighted three-dimensional water- and lipid-suppressed point-resolved spectroscopy pulse sequence. Voxels were classified into healthy peripheral zone, central gland, and periurethral zone and cancer tissue. Cancer voxels were classified according to cancer size and certainty in matching histopathologic findings with MR images. After visual inspection of automated fitting of classified voxels, the choline plus creatine-to-citrate (Cho + Cr/Cit) ratio was calculated for all tissues. Area under the receiver operating characteristic curves (A(z)) values were used to assess accuracy of discrimination of cancer from healthy tissues. P < .05 indicated a significant difference. RESULTS After exclusion of four patients with no voxels that passed visual inspection of the automated fit, a median of 82% of the classified voxels per patient was used in the analysis. Mean Cho + Cr/Cit ratios for healthy tissues were 0.22 +/- 0.12 (standard deviation) for peripheral zone, 0.34 +/- 0.14 for central gland, and 0.36 +/- 0.20 for periurethral area; all were significantly different from that of cancer (P < .001). A(z) for discrimination of probable and definite cancer tissue from healthy tissue for the peripheral zone (0.84) was significantly higher than that for the central gland (0.69) (P < .05). CONCLUSION Three-dimensional proton MR spectroscopy of the prostate, with a combination of only external radiofrequency surface coils at 3 T, can be used to discriminate cancer from healthy tissue.
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Affiliation(s)
- Tom W J Scheenen
- Department of Radiology, Radboud University Nijmegen Medical Centre, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands.
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Lange T, Trabesinger AH, Schulte RF, Dydak U, Boesiger P. Prostate spectroscopy at 3 Tesla using two-dimensional S-PRESS. Magn Reson Med 2007; 56:1220-8. [PMID: 17094089 DOI: 10.1002/mrm.21082] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Two-dimensional (2D) strong-coupling point-resolved spectroscopy (S-PRESS) is introduced as a novel approach to (1)H MR spectroscopy (MRS) in the prostate. The technique provides full spectral information and allows for an accurate characterization of the citrate (Cit) signal. The method is based on acquiring a series of PRESS spectra with constant total echo time (TE). The indirect dimension is encoded by varying the relative lengths of the first and second TEs (TE(1) + TE(2) = TE). In the resulting 2D spectra, only the signal of strongly coupled spin systems is spread into the second dimension, which leads to more clearly arranged spectra. Furthermore, the spectral parameters of Cit (coupling constant J and chemical shift difference delta of the AB spin system) can be determined with high accuracy in vivo. The sequence is analytically optimized for maximal "strong coupling peaks" of Cit at 3T. 2D S-PRESS spectra are compared with JPRESS spectra in vitro as well as in vivo.
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Affiliation(s)
- Thomas Lange
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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Chen AP, Cunningham CH, Kurhanewicz J, Xu D, Hurd RE, Pauly JM, Carvajal L, Karpodinis K, Vigneron DB. High-resolution 3D MR spectroscopic imaging of the prostate at 3 T with the MLEV-PRESS sequence. Magn Reson Imaging 2006; 24:825-32. [PMID: 16916699 DOI: 10.1016/j.mri.2006.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 03/02/2006] [Indexed: 11/15/2022]
Abstract
A 3 T MLEV-point-resolved spectroscopy (PRESS) sequence employing optimized spectral-spatial and very selective outer-voxel suppression pulses was tested in 25 prostate cancer patients. At an echo time of 85 ms, the MLEV-PRESS sequence resulted in maximally upright inner resonances and minimal outer resonances of the citrate doublet of doublets. Magnetic resonance spectroscopic imaging (MRSI) exams performed at both 3 and 1.5 T for 10 patients demonstrated a 2.08+/-0.36-fold increase in signal-to-noise ratio (SNR) at 3 T as compared with 1.5 T for the center citrate resonances. This permitted the acquisition of MRSI data with a nominal spatial resolution of 0.16 cm3 at 3 T with similar SNR as the 0.34-cm3 data acquired at 1.5 T. Due to the twofold increase in spectral resolution at 3 T and the improved magnetic field homogeneity provided by susceptibility-matched endorectal coils, the choline resonance was better resolved from polyamine and creatine resonances as compared with 1.5 T spectra. In prostate cancer patients, the elevation of choline and the reduction of polyamines were more clearly observed at 3 T, as compared with 1.5 T MRSI. The increased SNR and corresponding spatial resolution obtainable at 3 T reduced partial volume effects and allowed improved detection of the presence and extent of abnormal metabolite levels in prostate cancer patients, as compared with 1.5 T MRSI.
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Affiliation(s)
- Albert P Chen
- Department of Radiology, University of California at San Francisco, San Francisco, CA 94143-2512, USA
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19
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Gambarota G, van der Graaf M, Klomp D, Mulkern RV, Heerschap A. Echo-time independent signal modulations using PRESS sequences: a new approach to spectral editing of strongly coupled AB spin systems. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 177:299-306. [PMID: 16169267 DOI: 10.1016/j.jmr.2005.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 08/05/2005] [Accepted: 08/05/2005] [Indexed: 05/04/2023]
Abstract
In clinical MR spectroscopy, double spin-echo point resolved spectroscopy (PRESS) sequences are routinely used for volume selection. For strongly coupled AB spin systems under PRESS excitation, the dependence of the signal on the echo time TE has been thoroughly investigated, whereas less attention has been paid to the signal modulation which occurs at constant TE with varying interpulse delays. A substantial TE-independent J modulation is here predicted from analytical solutions of the Liouville equation and density matrix simulations, and verified with experiments on citrate at 1.5 and 3T. It is also shown that this modulation effect could be exploited for editing of strongly coupled AB resonances or for removal of singlets in spectra-by means of difference spectroscopy-just using a standard PRESS sequence. The applicability in vivo of this new spectral editing approach is also demonstrated, with selective detection of citrate resonances in the human prostate. This novel approach has the advantages of being simple, and directly applicable on standard clinical MR scanners, provided that the exact behavior of the resonance is known.
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Affiliation(s)
- G Gambarota
- Department of Radiology, Radboud University Nijmegen Medical Center, The Netherlands.
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20
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Trabesinger AH, Meier D, Dydak U, Lamerichs R, Boesiger P. Optimizing PRESS localized citrate detection at 3 Tesla. Magn Reson Med 2005; 54:51-8. [PMID: 15968673 DOI: 10.1002/mrm.20544] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Analytical methods are used to characterize the response of the strongly coupled two-spin system of citrate to point-resolved spectroscopy (PRESS)-based sequences at 3 T. The signal output is analyzed line by line, as well as in the Cartesian product operator basis. Patterns with a periodicity of 80.9 ms are identified. Furthermore, it is shown that at TE = n . 80.9 ms (n in {0,1,2,...}), the spin evolution can be described without direct reference to strong coupling terms. The theoretical results are found to be in good agreement with in vivo experiments. These results can be used to design protocols for prostate MRS and MRSI at 3 T, and give guidelines for optimizing spin-echo-based acquisition schemes for detecting two-spin systems at arbitrary field strengths.
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Affiliation(s)
- Andreas H Trabesinger
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
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21
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Kim DH, Margolis D, Xing L, Daniel B, Spielman D. In vivo prostate magnetic resonance spectroscopic imaging using two-dimensional J-resolved PRESS at 3 T. Magn Reson Med 2005; 53:1177-82. [PMID: 15844143 DOI: 10.1002/mrm.20452] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In vivo magnetic resonance spectroscopic imaging of the prostate using single-voxel and multivoxel two-dimensional (2D) J-resolved sequences is investigated at a main magnetic field strength of 3 T. Citrate, an important metabolite often used to aid the detection of prostate cancer in magnetic resonance spectroscopic exams, can be reliably detected along with the other metabolites using this method. We show simulations and measurements of the citrate metabolite using 2D J-resolved spectroscopy to characterize the spectral pattern. Furthermore, using spiral readout gradients, the single-voxel 2D J-resolved method is extended to provide the spatial distribution information as well all within a reasonable scan time (17 min). Phantom and in vivo data are presented to illustrate the multivoxel 2D J-resolved spiral chemical shift imaging sequence.
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Affiliation(s)
- Dong-hyun Kim
- Department of Radiology, Stanford University, CA 94305, USA.
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22
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Heikkinen S, Kangasmäki A, Timonen M, Kankaanranta L, Häkkinen AM, Lundbom N, Vähätalo J, Savolainen S. 1H MRS of a boron neutron capture therapy 10B-carrier, L-p-boronophenylalanine-fructose complex, BPA-F: phantom studies at 1.5 and 3.0 T. Phys Med Biol 2003; 48:1027-39. [PMID: 12741499 DOI: 10.1088/0031-9155/48/8/305] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The quantification of a BNCT 10B-carrier, L-p-boronophenylalanine-fructose complex (BPA-F), was evaluated using 1H magnetic resonance spectroscopy (1H MRS) with phantoms at 1.5 and 3.0 T. For proper quantification, relaxation times T1 and T2 are needed. While T1 is relatively easy to determine, the determination of T2 of a coupled spin system of aromatic protons of BPA is not straightforward with standard MRS sequences. In addition, an uncoupled concentration reference for aromatic protons of BPA must be used with caution. In order to determine T2, the response of an aromatic proton spin system to the MRS sequence PRESS with various echo times was calculated and the product of the response curve with exponential decay was fitted to the measured intensities. Furthermore, the response curve can be used to correct the intensities, when an uncoupled resonance is used as a concentration reference. BPA was quantified using both phantom replacement and internal water referencing methods with accuracies of +/- 5% and +/- 15%. Our phantom results suggest that in vivo studies on BPA concentration determination will be feasible.
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Affiliation(s)
- S Heikkinen
- Department of Radiology, Helsinki University Central Hospital, PO Box 340, FIN-00029 HUS, Helsinki, Finland.
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23
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Yue K, Marumoto A, Binesh N, Thomas MA. 2D JPRESS of human prostates using an endorectal receiver coil. Magn Reson Med 2002; 47:1059-64. [PMID: 12111951 DOI: 10.1002/mrm.10160] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A localized 2D J-resolved (JPRESS) MR spectroscopic sequence was evaluated in human prostates in vivo. Voxels of typically 2 ml were placed in the peripheral zone of the prostate. Eight healthy volunteers, three subjects with benign prostatic hyperplasia, and three patients with prostatic cancer were scanned on a 1.5T MR scanner, using a body coil for RF transmission and a pelvic phased-array coil combined with a disposable endorectal coil for signal reception. The total acquisition time for a 2D JPRESS spectrum was approximately 17 min. A major advantage of the endorectal 2D JPRESS was the ability to resolve the peaks of choline-containing compounds and those of spermine unequivocally. Spectral results clearly showed the biochemical changes in cancer and benign compared to healthy prostates, in conformity with ex vivo biochemical findings. The preliminary results suggest that the endorectal 2D JPRESS could be successfully implemented for the diagnostic examination of human prostates. .
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Affiliation(s)
- Kenneth Yue
- Department of Radiological Sciences, School of Medicine, University of California, Los Angeles, California, USA
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24
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Thompson RB, Allen PS. Response of metabolites with coupled spins to the STEAM sequence. Magn Reson Med 2001; 45:955-65. [PMID: 11378872 DOI: 10.1002/mrm.1128] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This article demonstrates that a numerical solution of the full quantum mechanical equations for all metabolites with coupled spins is an efficient and accurate means, first, of predicting the optimum STEAM sequence design for quantifying any target metabolite in brain, and, second, for providing the basis lineshapes and yields of these metabolites to facilitate their accurate quantification. Using as illustrations the weakly coupled AX3 system of lactate, the ABX aspartyl group of N-acetylaspartate, which has only two strongly coupled spins, and the much larger strongly coupled AMNPQ glutamyl group of glutamate, the numerical solutions for the response to STEAM highlight the principal source of response variability, namely, the evolution of and transfer between zero quantum terms during the mixing time, TM. These highlights include the rapid oscillations of zero quantum terms due to the chemical shift difference of the coupled spins, the proliferation of oscillating zero order terms due to strong coupling, and the serendipitous smoothing of the response as the number of strongly coupled spins increases. The numerical solutions also demonstrate that the design of the selective 90 degrees pulses is a far less critical factor in determining the response than was the case for the selective 180 degrees pulses of the PRESS sequence (Thompson and Allen, Magn Reson Med 1999;41:1162-1169). The veracity of the method is demonstrated both in phantom solutions and in the parietal lobe of a normal human brain.
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Affiliation(s)
- R B Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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25
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26
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Allen PS, Thompson RB. On the localized quantification of metabolites with coupled spins. MAGMA (NEW YORK, N.Y.) 1999; 9:159-63. [PMID: 10628693 DOI: 10.1007/bf02594616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- P S Allen
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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27
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Thompson RB, Allen PS. Sources of variability in the response of coupled spins to the PRESS sequence and their potential impact on metabolite quantification. Magn Reson Med 1999; 41:1162-9. [PMID: 10371448 DOI: 10.1002/(sici)1522-2594(199906)41:6<1162::aid-mrm12>3.0.co;2-n] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Using a numerical method of solving the equation of motion of the density matrix, an evaluation is presented of the sources of the marked variability in the response to the point resolved spectroscopy (PRESS) pulse sequence of coupled proton spin systems. The consequences of an inappropriate 180 degrees pulse design and of the limitations on radiofrequency power are demonstrated for a weakly coupled example, lactate. The dominating role of strong coupling, which is present in most brain metabolites, is demonstrated for glutamate, in which 160 terms in the density operator were tracked to monitor the gross changes in lineshape and signal intensity as a function of the two echo times. The predictions of the numerical solutions were confirmed by experiments on phantoms of aqueous metabolite solutions.
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Affiliation(s)
- R B Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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28
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Straubinger K, Schick F, Lutz O. Influence of pulse angle variations on stimulated echo acquisition mode proton nuclear magnetic resonance spectra of AB spin systems: theory and experiments with citrate. MAGMA (NEW YORK, N.Y.) 1998; 7:88-94. [PMID: 9951769 DOI: 10.1007/bf02592233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The influence of pulse angle variations in the localization sequence stimulated echo acquisition mode (STEAM) on the signal of strongly coupled AB spin systems has been examined. Experimental 1H nuclear magnetic resonance (NMR) spectra of citrate were recorded on a 1.5 T whole-body imager. Theoretically calculated spectra were generated, with good correlation to experimental results. The dependence of the signal intensity on sequence timing and pulse angles was calculated analytically. For longer sequence timings, the ratio of the signal intensity from citrate to the signal intensity from uncoupled nuclei depends strongly on the applied flip angles. The shape of spectra also changes with varying flip angles. These effects are clearly less pronounced for STEAM than for point resolved spectroscopy (PRESS). The results have to be considered for quantitative measurements of citrate in spectroscopic investigations as, e.g. of prostate neoplasms.
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Affiliation(s)
- K Straubinger
- Physikalisches Institut, Universität Tübingen, Germany
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29
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Thompson RB, Allen PS. A new multiple quantum filter design procedure for use on strongly coupled spin systems found in vivo: its application to glutamate. Magn Reson Med 1998; 39:762-71. [PMID: 9581608 DOI: 10.1002/mrm.1910390514] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A numerical procedure is outlined that is appropriate for the design of multiple quantum filter sequences targeted for the strongly coupled, multiple spin systems that occur in metabolites present in brain. The procedure uses numerical methods of solution of the density matrix equations, first, to establish the most appropriate resonance to target with the filter; second, to provide contour plots of a performance index of the filter in terms of critical sequence parameters; and third, to produce the response signals of the target and the background metabolites to the optimized filter. The procedure is exemplified for the AMNPQ spin system of the amino acid glutamate at a field strength of 3 T. The 2.3 ppm peak of the PQ multiplet of glutamate was identified as the target resonance, and the performance of the filter so derived was evaluated experimentally on phantom solutions and in human brain. These experiments clearly demonstrate that a linewidth of <or=4 Hz is required for full resolution of glutamate from glutamine at 3 T using this double quantum filter. Nevertheless, even at a linewidth of approximately 7 Hz in vivo, the 2.3 ppm peak of glutamate dominates the filter response and thereby removes a significant cause of uncertainty in measuring changes in glutamate by eliminating most of the background observed in unedited spectra obtained using PRESS or STEAM.
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Affiliation(s)
- R B Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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30
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Abstract
An outline is presented of metabolite-specific in vivo NMR spectroscopy (particularly in brain). It reviews from a physical spectroscopist's perspective, the need for and the methods of observation of, individual metabolite resonances.
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Affiliation(s)
- P S Allen
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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31
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van der Graaf M, Jager GJ, Heerschap A. Removal of the outer lines of the citrate multiplet in proton magnetic resonance spectra of the prostatic gland by accurate timing of a point-resolved spectroscopy pulse sequence. MAGMA (NEW YORK, N.Y.) 1997; 5:65-9. [PMID: 9219182 DOI: 10.1007/bf02592268] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Proton MR spectra of a healthy human prostatic gland show a major signal for citrate appearing as an AB-type multiplet. After application of multipulse localization sequences, the outer lines of this multiplet often appear with dispersion line shapes disturbing the baseline and interfering with proper quantification of citrate itself and other nearby resonances. Based upon analytical descriptions of the time evaluation of an AB spin system during a point resolved spectroscopy (PRESS) pulse sequence (90x-tau 1-180y-tau 2-180y-t), equations were derived representing the intensity of the absorption and dispersion line shape of the outer lines of the citrate multiplet at the top of echo t = tau 2-tau 1. From these equations, it was calculated that the outer lines of citrate can be removed almost completely using a PRESS pulse sequence with tau 1 = 11 ms and tau 2 = 60 ms. The theoretical description was confirmed by the almost complete disappearance of the two outer citrate resonances in in vitro and in vivo proton MR spectra acquired with this pulse sequence timing.
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Affiliation(s)
- M van der Graaf
- University Hospital Nijmegen, Department of Radiology, The Netherlands
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32
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Mulkern RV, Bowers JL, Peled S, Kraft RA, Williamson DS. Citrate signal enhancement with a homonuclear J-refocusing modification to double-echo PRESS sequences. Magn Reson Med 1996; 36:775-80. [PMID: 8916029 DOI: 10.1002/mrm.1910360517] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The citrate signal at field strengths of whole body imagers arises from two sets of two strongly coupled methylene protons. This causes citrate spectra acquired with standard in vivo localization schemes like the double-echo point resolved echo spectroscopy (PRESS) sequence to have complicated dependencies on timing parameters. A homonuclear J-refocused version of the double-echo PRESS sequence that has previously been shown to completely remove J-modulations from weakly coupled AX systems is considered for its potential in acquiring signal from the strongly coupled AB system of citrate. An analytic solution to the problem is derived with the density matrix formalism and verified both numerically and experimentally for 7 T conditions. The general expression for the AB signal is applied to study the 1.5 T citrate signal where a substantial signal enhancement over conventional double-echo PRESS sequences is predicted and verified for echo times in the 150 to 300 ms range.
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Affiliation(s)
- R V Mulkern
- Department of Radiology, Children's Hospital, Boston, MA 02115, USA
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33
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Lowry M, Liney GP, Turnbull LW, Manton DJ, Blackband SJ, Horsman A. Quantification of citrate concentration in the prostate by proton magnetic resonance spectroscopy: zonal and age-related differences. Magn Reson Med 1996; 36:352-8. [PMID: 8875404 DOI: 10.1002/mrm.1910360305] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A commercial phased-array multicoil was used to acquire water-suppressed localized proton spectra of the two major anatomical regions of the prostate. The signal-to-noise ratio and spectral resolution allowed identification of peaks from choline and creatine, as well as a major peak from citrate. Quantification of the citrate peak using experimentally determined relaxation parameters with tissue water as an internal concentration reference revealed a marked variability between different volunteers. Nevertheless, in each case, the citrate concentration was up to fourfold greater in the peripheral zone than in the central gland. Furthermore, the difference in citrate concentration between these two regions was positively correlated with the subjects age. The results indicate a consistent difference in cellular function between the major anatomical regions within the prostate and may have important consequences for the application of magnetic resonance spectroscopy to the diagnosis of prostatic pathology.
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Affiliation(s)
- M Lowry
- Centre for Magnetic Resonance Investigations, University of Hull, United Kingdom
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34
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Liney GP, Lowry M, Turnbull LW, Manton DJ, Knowles AJ, Blackband SJ, Horsman A. Proton MR T2 maps correlate with the citrate concentration in the prostate. NMR IN BIOMEDICINE 1996; 9:59-64. [PMID: 8887369 DOI: 10.1002/(sici)1099-1492(199604)9:2<59::aid-nbm400>3.0.co;2-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A significant correlation between water T2 relaxation time and citrate concentration in the normal prostate is demonstrated using spatially localized spectroscopy and water T2 maps. These data imply that MR images may be used to infer the concentration of citrate at high spatial resolution. Preliminary results in patients demonstrate that this relationship is maintained in benign prostatic hyperplasia (BPH) and prostatic carcinoma. The determination of citrate concentration and water T2 may aid the differentiation of prostate carcinoma from BPH and normal tissue.
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Affiliation(s)
- G P Liney
- Department of Medical Physics, University of Hull, UK
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35
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Schick F, Straubinger K, Machann J, Nägele T, Bunse M, Klose U, Lutz O. Sequence parameters of double spin-echo sequences affect quantification of citrate. Magn Reson Imaging 1996; 14:663-72. [PMID: 8897371 DOI: 10.1016/0730-725x(96)00096-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Quantification of citrate by localized 1H spectroscopy is usually performed using the water signal as reference, but the signal behavior of the J-coupled AB spin system of citrate after multipulse excitation is not as trivial as for uncoupled substances. The influence of the timing scheme of double spin-echo sequences and of the spatial flip angle distribution of (nonideal) refocusing pulses was analyzed systematically for the citrate resonances. Both single echo times of the double spin-echo sequence were varied between 20 ms and 250 ms in theoretical and experimental approaches. Relatively long total echo times (TE > 120 ms) provide high selectivity to citrate signals, since signals from triglycerides at 2.6 ppm are markedly reduced. Asymmetrical timing schemes of the double spin-echo sequence with one short single echo time of 20 ms and one longer single echo time of about 120 ms result in high integral signal from the central lines of citrate, whereas symmetrical timing leads to high sensitivity for total echo times TE near 100 ms. The integral citrate signals in spectra with relatively long echo times (TE > 120 ms) were found to depend markedly on the type of the refocusing pulses, affecting quantitative citrate measurements in vitro and in vivo.
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Affiliation(s)
- F Schick
- Department of Diagnostic Radiology, University of Tübingen, Germany
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