Quantitative 1H MR spectroscopic imaging of the prostate gland using LCModel and a dedicated basis‐set: Correlation with histologic findings

Proton magnetic resonance spectroscopic imaging (¹H‐MRSI) has been advocated as a valuable tool for prostate cancer diagnosis. However, a barrier to widespread clinical use of this technique is the lack of robust quantification methods that yield reproducible results in an institution‐independent manner. The main goal of this study was to develop a standardized and fully automated approach (LCModel‐based) for quantitative prostate ¹H‐MRSI. To this end, a dedicated basis set was constructed by the combination of simulated (citrate, Cit; choline, Cho, and creatine, CR) and experimentally acquired (spermine, Spm) spectra. The overlapping Spm, Cho, and Cr could be resolved and quantified individually, thus allowing for the independent assessment of glandular (Cit and Spm) and proliferative (Cho) components. Several metabolite ratios were calculated and compared to the histologic findings of prostatectomy specimens from 10 prostate cancer patients with Gleason scores (3 + 3) and (3 + 4). The Cho mole fraction and the Cho/(Cit + Spm) ratio were found to best discriminate between prostate cancer and healthy tissue. The comparison between the quantitative MRSI results and the histologic findings suggests that no correlation exists between the detected metabolic alterations and the Gleason score of low‐grade tumors. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

Quantitative J-resolved prostate spectroscopy using two-dimensional prior-knowledge fitting.

Two-dimensional (2D) prior-knowledge fitting (ProFit) was adapted and applied for the quantification of J-resolved (JPRESS) spectra acquired at a field strength of 3T from the human prostate in vivo. In contrast to methods based on simple line fitting and peak integration, commonly applied for metabolite quantification in the prostate, ProFit yields metabolite concentration ratios that are independent of sequence and field strength, since it is based on the linear combination of 2D basis spectra. It is demonstrated that ProFit benefits from the increased information content and reduced baseline distortion in JPRESS prostate spectra, in particular for the quantification of coupled metabolites like citrate (Cit), spermine (Spm), and myo-inositol (mI). The method is validated with 10 repetitive prostate measurements on the same subject. Furthermore, a study carried out on 10 healthy subjects shows that the six prostate metabolites creatine (Cr), total choline (Cho), Cit, Spm, mI, and scyllo-inositol (sI) can be reliably detected in vivo, some of which--especially total Cho and Cit--have proven to be useful markers for the detection of prostate cancer.     

3D 1 HMRSI对外周带前列腺癌鉴别诊断价值的初步研究

目的:探讨3D1HMRSI(three dimensional proton MR spectroscopic imaging)研究外周带前列腺癌(PCa)的代谢特点,及对外周带PCa的鉴别诊断价值。方法:分析18例良性前列腺增生(BPH)和21例PCa的3D MRSI表现。测量外周带PCa体素及BPH外周带体素的(Cho Cre)/Cit及Cho/Cre,并比较它们之间的差异。结果:BPH的外周带波谱主要表现为Cit高耸,Cho次之,Cre最低;PCa波谱主要表现为Cit峰明显下降甚至消失,Cho显著升高,两者波峰可呈现倒置,(Cho Cre)/Cit>0.86。PCa体素的(Cho Cre)/Cit显著高于BPH体素,且两者仅存在小部分重叠,PCa体素的Cho/Cre也显著高于BPH体素,但两者存在较大部分重叠;经ROC曲线分析得出(Cho Cre)/Cit对外周带PCa的鉴别诊断效能高于Cho/Cre,(Cho Cre)/Cit对外周带PCa的最佳诊断阈值为1.16。结论:外周带PCa的3D MRSI表现具有特征性,(Cho Cre)/Cit为诊断外周带PCa的有效指标,以(Cho Cre)/Cit>1.16作为诊断标准,可获得较高的敏感度、特异度和准确度(分别为99.3%、99.2%、99.3%)。     

MR spectroscopic imaging and diffusion-weighted imaging of prostate cancer with Gleason scores

Purpose:

To investigate functional changes in prostate cancer patients with three pathologically proven different Gleason scores (GS) (3+3, 3+4, and 4+3) using magnetic resonance spectroscopic imaging (MRSI) and diffusion‐weighted imaging (DWI).

Materials and Methods:

In this study MRSI and DWI data were acquired in 41 prostate cancer patients using a 1.5T MRI scanner with a body matrix combined with an endorectal coil. The metabolite ratios of (Cho+Cr)/Cit were calculated from the peak integrals of total choline (Cho), creatine (Cr), and citrate (Cit) in MRSI. Apparent diffusion coefficient (ADC) values were derived from DWI for three groups of Gleason scores. The sensitivity and specificity of MRSI and DWI in patients were calculated using receiver operating characteristic curve (ROC) analysis.

Results:

The mean and standard deviation of (Cho+Cr)/Cit ratios of GS 3+3, GS 3+4, and GS 4+3 were: 0.44 ± 0.02, 0.56 ± 0.06, and 0.88 ± 0.11, respectively. For the DWI, the mean and standard deviation of ADC values in GS 3+3, GS 3+4, and GS 4+3 were: 1.13 ± 0.11, 0.97 ± 0.10, and 0.83 ± 0.08 mm²/sec, respectively. Statistical significances were observed between the GS and metabolite ratio as well as ADC values and GS.

Conclusion:

Combined MRSI and DWI helps identify the presence and the proportion of aggressive cancer (ie, Gleason grade 4) that might not be apparent on biopsy sampling. This information can guide subsequent rebiopsy management, especially for active surveillance programs. J. Magn. Reson. Imaging 2012;36:697–703. © 2012 Wiley Periodicals, Inc.     

3 D1HMRSI对外周带前列腺癌的鉴别诊断价值

目的应用3D1HMRSI(3D MRSI)研究外周带前列腺癌(PCa)的代谢特点,并初步探讨3DMRSI对外周带PCa的鉴别诊断价值方法分析18例良性前列腺增生(BPH)和21例PCa的3D MRSI表现测量外周带PCa体素及BPH外周带体素的(Cho Cre)/Cit及Cho/Cre,并分别比较PCa体素及BPH体素2组代谢物比值结果BPH的外周带波谱主要表现为Cit高耸,Cho次之,Cre最低,PCa波谱主要表现为Cit峰明显下降甚至消失,Cho显著升高,两者波峰可呈现倒置;PCa体素的(Cho Cre)/Cit显著高于BPH体素,两者仅存在小部分重叠,PCa体素的Cho/Cre也显著高于BPH体素,但两者存在较大部分重叠结论外周带PCa的3D MRSI表现具有特征性,(Cho Cre)/Cit是诊断外周带PCa的有效指标     

中央腺体内前列腺癌3D 1 H-MRSI的初步研究

目的 应用3D氢质子磁共振波谱成像（3D ^1H-MRSI）研究中央腺体（CG）前列腺癌（PC）的代谢特点,并初步探讨3D ^1H-MRSI对CG内PC的鉴别诊断价值。资料与方法 分析18例良性前列腺增生（BPH）和16例PC的3D ^1H-MRSI表现,16例PC中2例源于CG,14例肿块较大同时累及外周带和CG。测量CG内PC及BPH的CG体素（Cho＋Cre）／Cit比值及Cho／Cre比值,并分别对PC与BPH体素的两组代谢物比值进行比较。结果 CG内PC波谱主要表现为Cit峰明显下降甚至消失,Cho峰显著升高,两者波峰可呈现倒置。CG的腺体增生组织主要表现为Cit峰高耸,Cho峰次之,Cre峰最低,基质增生者Cit、Cho峰均降低;CG内PC体素（Cho＋Cre）／Cit比值显著高于BPH的CG（P〈0．001）,但两组体素存在部分重叠（29／133,21．8％）。CG内PC体素的Cho／Cre比值明显高于BPH的CG（P〈0．001）,但两组之间重叠较多（105／133,78．9％）。结论 CG内PC的诊断存在一定困难,其（Cho＋Cre）／Cit明显高于BPH的CG,但与BPH有部分重叠,综合Cit峰降低、Cho峰升高、Cho／Cre增大有助于CG内PC的检出。     

Combined quantitative dynamic contrast-enhanced MR imaging and (1)H MR spectroscopic imaging of human prostate cancer

PURPOSE: To differentiate prostate carcinoma from healthy peripheral zone and central gland using quantitative dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging and two-dimensional (1)H MR spectroscopic imaging (MRSI) combined into one clinical protocol. MATERIALS AND METHODS: Twenty-three prostate cancer patients were studied with a combined DCE-MRI and MRSI protocol. Cancer regions were localized by histopathology of whole mount sections after radical prostatectomy. Pharmacokinetic modeling parameters, K(trans) and k(ep), as well as the relative levels of the prostate metabolites citrate, choline, and creatine, were determined in cancer, healthy peripheral zone (PZ), and in central gland (CG). RESULTS: K(trans) and k(ep) were higher (P < 0.05) in cancer and in CG than in normal PZ. The (choline + creatine)/citrate ratio was elevated in cancer compared to the PZ and CG (P < 0.05). While a (choline + creatine)/citrate ratio above 0.68 was found to be a reliable indicator of cancer, elevated K(trans) was only a reliable cancer indicator in the diagnosis of individual patients. K(trans) and (choline + creatine)/citrate ratios in cancer were poorly correlated (Pearson r(2) = 0.07), and thus microvascular and metabolic abnormalities may have complementary value in cancer diagnosis. CONCLUSION: The combination of high-resolution spatio-vascular information from dynamic MRI and metabolic information from MRSI has excellent potential for improved localization and characterization of prostate cancer in a clinical setting. J. Magn. Reson. Imaging 2004;20:279-287. Copyright 2004 Wiley-Liss, Inc.     

MRI和MRS对前列腺疾病的鉴别诊断价值

目的探讨MRI和MRS在前列腺疾病中的鉴别诊断价值。方法回顾分析经病理证实的22例患者的临床资料及MRI和MRS所见,其中包括前列腺良性增生(BPH)16例及前列腺癌(PC)6例。MRI观察前列腺大小、病变位置、信号特点和肿瘤侵犯程度,MRS观察枸橼酸盐(Cit)、胆碱复合物(Cho)和肌酸(Cr)的化学位移及(Cho Cr)/Cit比值。结果16例BPH中,前列腺弥漫性增大,T2W均示前列腺中央叶明显增大,其中13例表现为多个大小不等类圆形高和/或低信号结节,部分低信号结节周围可见低信号假包膜,外围带受压变窄。6例PC中5例均表现为T2W外周带中见低信号区,1例表现为中央叶前部较大低信号结节;2例位于包膜内,4例突破包膜侵犯精囊腺和血管神经束,其中1例伴有盆腔淋巴结肿大和骨盆骨转移。MRS上BPH患者Cit明显升高,Cho略升高,(Cho Cr)/Cit比值不高,平均0.60。PC患者,Cit明显下降,Cho明显升高,(Cho Cr)/Cit比值升高,平均2.51。分别对PC与BPH体素的2组代谢物比值进行比较,二者之间有显著的统计学差异(t=0.353,P<0.05)。结论MRI和MRS有助于PC和BPH的鉴别诊断。     

Transition zone prostate cancer: metabolic characteristics at 1H MR spectroscopic imaging--initial results

PURPOSE: To determine whether cancers of the prostate transition zone (TZ) possess a unique metabolic pattern by which they may be identified at proton magnetic resonance (MR) spectroscopic imaging. MATERIALS AND METHODS: Findings in 40 patients who underwent combined endorectal MR imaging and hydrogen 1 MR spectroscopic imaging before radical prostatectomy and who had TZ tumor identified subsequently at step-section pathologic analysis were retrospectively reviewed. Within this population, a subset of 16 patients whose TZ tumor had a largest diameter of 1 cm or greater and was included in the MR spectroscopic imaging excitation volume was identified. In these 16 patients, the ratios of choline-containing compounds (Cho) and creatine/phosphocreatine (Cr) to citrate (Cit) (ie, [Cho + Cr]/Cit), Cho/Cr, and Cho/Cit were compared in tumor and control tissues. The presence of only Cho and the absence of all metabolites were also assessed. RESULTS: The mean values of (Cho + Cr)/Cit, Cho/Cr, and Cho/Cit were different between TZ cancer and control tissues (P =.001, P =.003, and P =.001, respectively; Wilcoxon signed rank test). Nine (56%) of 16 patients had at least one tumor voxel in which Cho comprised the only detectable peak, while no control voxels showed only Cho (P =.008, McNemar test). The percentage of voxels in which no metabolites were detected did not differ between tumor and control tissues (P =.134, McNemar test). CONCLUSION: TZ cancer has a metabolic profile that is different from that of benign TZ tissue; however, the broad range of metabolite ratios observed in TZ cancer precludes the use of a single ratio to differentiate TZ cancer from benign TZ tissue.     

3D proton MR spectroscopic imaging of prostate cancer using a standard spine coil at 1.5 T in clinical routine: a feasibility study

The objective of this study was to demonstrate the feasibility of 3D proton MR spectroscopic imaging (MRSI) of the prostate using a standard spine instead of a dedicated endorectal coil at 1.5 T. Twenty-eight patients (25 with biopsy proven prostate cancers and three patients with a benign prostate hyperplasia) were examined. MRI and MRSI were conducted with commercial array surface coils at 1.5 T. Ratios of choline (Cho), creatine (Cr) and citrate (Ci) were calculated for tumour, central and peripheral zone retrospectively, based on axial T2 weighed MR images and histology reports. Prostate cancer was characterized by significantly elevated (Cho+Cr)/Ci ratio compared with non-tumourous prostate tissue. The quality of all proton MR spectra was considered to be good or acceptable in 17/28 patients (61%) and poor in 11/28 (39%) examinations. In 20/25 patients with proven malignancy (80%), MRSI was considered to be helpful for the detection of prostate cancer. In 4/25 patients with proven malignancy (16%) who underwent seed implantation, radiotherapy or hormone deprivation before MR examination spectroscopy was of poor and non-diagnostic quality. MRSI of the prostate is feasible within clinical routine using the spine array surface coil at 1.5 T. It can consequently be applied to patients even with contraindications for endorectal coils. However, spectral quality and signal-to-noise ratio is clearly inferior to 3D MRSI examinations with endorectal coils.     

Combined morphological, [1H]-MR spectroscopic and contrast-enhanced imaging of human prostate cancer with a 3-Tesla scanner: preliminary experience

PURPOSE: The objective of this study was to explore the feasibility of combined morphological magnetic resonance imaging (MRI), [(1)H]magnetic resonance spectroscopic imaging (MRSI) and quantitative dynamic contrast-enhanced MRI (DCE-MRI) of human prostate cancer at 3 Tesla using a pelvic phased-array coil. MATERIALS AND METHODS: MRI, MRSI and DCE-MRI with a 3-Tesla whole-body scanner were performed in 30 patients with biopsy-proven prostate cancer before radical prostatectomy. High-resolution T2-weighted turbo spin echo (TSE) images were evaluated for visualisation of the peripheral zone, central gland, visibility of the cancer lesion, prostatic capsule delineation and overall image quality according to a five-point scale. Relative levels of the prostate metabolites citrate, choline and creatine were determined in cancer and in the normal peripheral zone (PZ) and central gland (CG). Spectra were also evaluated for the separation of the signal of citrate, choline and creatine and suppression of lipid and water signals. Time-intensity curves were obtained for prostatic cancer and healthy PZ and CG from DCE-MRI. Finally, time of arrival, time to peak, maximum enhancement and wash-in rate in cancer, normal PZ and CG were calculated. RESULTS: The high signal-to-noise ratio (SNR) at 3 Tesla provided T2-weighted TSE images with excellent anatomical detail (in-plane voxel size of 0.22 x 0.22 mm) and good T2 contrast. The increased spectral resolution was sufficient to separate the choline and creatine resonances and allow delineation of the four peaks of citrate resonance. The (choline + creatine)/citrate ratio was elevated in cancer in comparison with PZ and CG (p<0.001). Dynamic contrast-enhanced images showed good temporal resolution. All parameters obtained from DCE-MRI showed a statistically significant (P<0.05) difference between cancer tissue and normal PZ and CG. Wash-in rate and (choline+creatine)/citrate ratio were significantly correlated (r=0.713, P=0.001) in PZ cancer, whereas the correlation was not significant (r=0.617, P=0.06) in CG and in PZ (r=0.530, P=0.08). CONCLUSIONS: It is possible to perform MRI of prostate cancer at 3 Tesla using a pelvic phased-array coil with high spatial, temporal and spectral resolution. The combination of vascular information from DCE-MRI and metabolic data from MRSI has excellent potential for improved accuracy in delineating and staging prostate carcinoma. These results suggest that high magnetic field strengths offer the possibility of studying prostate cancer without use of an endorectal coil.     

Time-dependent effects of hormone-deprivation therapy on prostate metabolism as detected by combined magnetic resonance imaging and 3D magnetic resonance spectroscopic imaging.

Combined MRI and 3D spectroscopic imaging (MRI/3D-MRSI) was used to study the metabolic effects of hormone-deprivation therapy in 65 prostate cancer patients, who underwent either short, intermediate, or long-term therapy, compared to 30 untreated control patients. There was a significant time-dependent loss of the prostatic metabolites choline, creatine, citrate, and polyamines during hormone-deprivation therapy, resulting in the complete loss of all observable metabolites (total metabolic atrophy) in 25% of patients on long-term therapy. The amount and time-course of metabolite loss during therapy significantly differed for healthy and malignant tissues. Citrate levels decreased faster than choline and creatine levels during therapy, resulting in an increase in the mean (choline + creatine)/citrate ratio with duration of therapy. Due to a loss of all MRSI detectable citrate, this ratio could not be used to identify cancer in 69% of patients on long-term therapy. In the absence of citrate, however, residual prostate cancer could still be detected by elevated choline levels (choline/creatine ratio > or =1.5), or the presence of only choline in the proton spectrum. The loss of citrate and the presence of total metabolic atrophy correlated roughly with decreasing serum prostatic specific antigen levels with increasing therapy. In summary, MRI/3D-MRSI provided both a measure of residual cancer and a time-course of metabolic response following hormone-deprivation therapy. Magn Reson Med 46:49-57, 2001.     

以穿刺活检为金标准对前列腺MRS检查评价指标选择的研究

目的 探讨方便实用的术前诊断前列腺癌的MRS半定量指标.方法 选择行前列腺MRS检查并经穿刺活检病理证实、临床资料齐全的初诊前列腺疾病患者100例进行MRS分析,测量可用体素的(胆碱+肌酸)枸椽酸盐[(Cho+Cr)/Cit]值,并计算前列腺外周带各分区的(Cho+Cr)/Cit平均值、阳性体素比及整个前列腺(Cho+Cr)/Cit平均值、阳性体素比最大值和阳性体素比平均值,分别在6分区中的每个分区和前列腺整体水平评价各种指标诊断前列腺癌的效能,并分别利用配对卡方检验和Kappa检验判断各指标诊断前列腺癌准确性的差异和一致性.结果 100例共获得符合可用标准的体素2945个,其中前列腺癌区1203个,非前列腺癌区1742个,癌区体素(Cho+Cr)/Cit值范围0.22～8.00,中位数为1.87;非癌区体素(Cho+Cr)/Cit值范围0.11～8.00,中位数为0.53,癌区体素的(Cho+Cr)/Cit值大于非癌区(Z=28.48,P<0.01),但有部分重叠.在分区水平,应用如下MRS指标诊断前列腺癌的敏感性、特异性、阳性预测值、阴性预测值和准确性为:(1)以单个体素(Cho+Cr)/Cit值>0.911为标准时:81.4%(179/220)、64.2%(194/302)、62.4%(179/287)、82.6%(194/235)、71.5%(373/522);(2)以(Cho+Cr)/Cit平均值>0.911为标准时:77.3%(170/220)、77.2%(233/302)、71.1%(170/239)、82.3%(233/283)、77.2%(403/522);(3)以阳性体素比>0.519为标准时:73.2%(161/220)、80.8%(244/302)、73.5%(161/219)、80.8%(244/302)、77.6%(405/522).其中(Cho+Cr)/Cit平均值和阳性体素比一致性较高(Kappa=0.907).在整体水平,上述值分别为:(1)以单个体素(Cho+Cr)/Cit值>0.911为标准时:94.3%(50/53)、40.4%(19/47)、64.1%(50/78)、86.4%(19/22)、69.0%(69/100);(2)以(Cho+Cr)/Cit平均值>0.911为标准时:73.6%(39/53)、83.0%(39/47)、83.0%(39/47)、73.6%(39/53)、78.0%(78/100);(3)以阳性体素比最大值>0.519为标准时:88.7%(47/53)、61.7%(29/47)、72.3%(47/65)、82.9%(29/35)、76.0%(76/100);(4)以阳性体素比平均值>0.519为标准时:62.3%(33/53)、85.1%(40/47)、82.5%(33/40)、66.7%(40/60)、73.0%(73/100).其中(Cho+Cr)/Cit平均值与阳性体素比平均值之间一致性较高(Kappa=0.818).结论 诊断临床可疑前列腺癌人群时建议选用单个体素标准,用于指导穿刺活检定位时建议选用阳性体素比最大值标准.     

Correlation of proton MR spectroscopic imaging with gleason score based on step-section pathologic analysis after radical prostatectomy

PURPOSE: To determine whether hydrogen 1 magnetic resonance (MR) spectroscopic imaging can be used to predict aggressiveness of prostate cancer. MATERIALS AND METHODS: All patients gave informed consent according to an institutionally approved research protocol. A total of 123 patients (median age, 58 years; age range, 40-74 years) who underwent endorectal MR imaging and MR spectroscopic imaging between January 2000 and December 2002 were included. MR imaging and spectroscopy were performed by using combined pelvic phased-array and endorectal probe. Water and lipids were suppressed, and phase-encoded data were acquired with 6.2-mm resolution. Voxels in the peripheral zone were considered suspicious for cancer if (Cho + Cr)/Cit was at least two standard deviations above the normal level, where Cho represents choline-containing compounds, Cr represents creatine and phosphocreatine, and Cit represents citrate. Correlation between metabolite ratio and four Gleason score groups identified at step-section pathologic evaluation (3 + 3, 3 + 4, 4 + 3, and > or =4 + 4) was assessed with generalized estimating equations. RESULTS: Data from 94 patients were included. Pathologic evaluation was used to identify 239 lesions. Overall sensitivity of MR spectroscopic imaging was 56% for tumor detection, increasing from 44% in lesions with Gleason score of 3 + 3 to 89% in lesions with Gleason score greater than or equal to 4 + 4. There was a trend toward increasing (Cho + Cr)/Cit with increasing Gleason score in lesions identified correctly with MR spectroscopic imaging. Tumor volume assessed with MR spectroscopic imaging increased with increasing Gleason score. CONCLUSION: MR spectroscopic imaging measurement of prostate tumor (Cho + Cr)/Cit and tumor volume correlate with pathologic Gleason score. There is overlap between MR spectroscopic imaging parameters at various Gleason score levels, which may reflect methodologic and physiologic variations. MR spectroscopic imaging has potential in noninvasive assessment of prostate cancer aggressiveness.     

31P NMR of phospholipid metabolites in prostate cancer and benign prostatic hyperplasia

¹H MRSI in vivo is increasingly being used to diagnose prostate cancer noninvasively by measurement of the resonance from choline‐containing phospholipid metabolites. Although ³¹P NMR in vivo or in vitro is potentially an excellent method for probing the phospholipid metabolites prominent in prostate cancer, it has been little used recently. Here, we report an in vitro ³¹P NMR comparison of prostate cancer and benign prostatic hyperplasia, focusing on the levels of the major phospholipid metabolites. Unlike phosphocholine and glycerophosphocholine, phosphoethanolamine and glycerophosphoethanolamine (and their ratio) were significantly different between cancer and benign prostatic hyperplasia. The high level of phosphoethanolamine+glycerophosphoethanolamine relative to phosphocholine+glycerophosphocholine suggests that the former may be significant contributors to the “total choline” resonance observed by ¹H MRSI in vivo. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Anatomical and metabolic assessment of prostate using a 3-Tesla MR scanner with a custom-made external transceive coil: healthy volunteer study

PURPOSE: To examine the possibility of using a 3 Tesla (T) magnetic resonance (MR) scanner with a custom-made external coil to obtain ductal details of the prostate, high-quality spectra, and metabolite mapping corresponding to prostate zonal anatomy in healthy volunteers. MATERIALS AND METHODS: MRI and two-dimensional (2D) chemical shift imaging (CSI) were performed in 16 healthy volunteers using a 3T scanner with a custom-made external transmit-receive (transceive) coil. Visualization of the prostatic duct-like structure was analyzed on T2-weighted (T2W) images. The resolution of the metabolite peaks and the distribution of metabolites in CSI were also assessed. RESULTS: In the axial plane, 3-mm-thick images were better than 4-mm-thick images with the same voxel volume for assessing duct-like structures and prostatic urethra. Differentiation between inner and outer citrate (Cit) peaks was frequently observed (29 out of 30). The mean peak area ratio of choline (Cho) plus creatine (Cr) over Cit in the peripheral zone (PZ) was significantly lower than in the transition zone (TZ) (P = 0.014). CONCLUSION: 3T MR examinations of the prostate using an external coil allow information to be collected about the details of duct-like structures, the high-quality spectra of Cit, and the zone-specific distribution of metabolites.     

Prostate cancer metabolite quantification relative to water in 1H‐MRSI in vivo at 3 Tesla

¹H magnetic resonance spectroscopic imaging was performed on 16 men with suspected prostate cancer using an 8‐channel external receive coil at 3 T. Choline and citrate (Cit) signals were measured in prostate lesions and normal‐appearing peripheral zone as identified on T₂‐weighted images. Metabolites were quantified relative to unsuppressed water from a separately acquired magnetic resonance spectroscopic imaging dataset using LCModel. Validation experiments were also performed in a phantom containing physiological concentrations of choline, Cit, and creatine. In vitro, fair agreement between measured and true concentrations was observed, with the greatest discrepancy being a 35% underestimation of Cit. In vivo, one dataset was rejected for failure to meet the quality criterion of linewidth <15 Hz, and in 6 of 15 subjects, insufficient normal‐appearing peripheral zone tissue was identified for study. Lesions were found to have higher choline and choline/Cit, and lower Cit, than normal‐appearing peripheral zone. The smaller skew of data obtained using water normalization in comparison with metabolite ratios suggests potential usefulness in longitudinal tumor monitoring and in studies of treatment effects. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Reproducibility of 3D 1H MR spectroscopic imaging of the prostate at 1.5T

Purpose:

To determine the reproducibility of 3D proton magnetic resonance spectroscopic imaging (¹H‐MRSI) of the human prostate in a multicenter setting at 1.5T.

Materials and Methods:

Fourteen subjects were measured twice with 3D point‐resolved spectroscopy (PRESS) ¹H‐MRSI using an endorectal coil. MRSI voxels were selected in the peripheral zone and combined central gland at the same location in the prostate in both measurements. Voxels with approved spectral quality were included to calculate Bland–Altman parameters for reproducibility from the choline plus creatine to citrate ratio (CC/C). The repeated spectroscopic data were also evaluated with a standardized clinical scoring system.

Results:

A total of 74 voxels were included for reproducibility analysis. The complete range of biologically interesting CC/C ratios was covered. The overall within‐voxel standard deviation (SD) of the CC/C ratio of the repeated measurements was 0.13. This value is equal to the between‐subject SD of noncancer prostate tissue. In >90% of the voxels the standardized clinical score did not differ relevantly between the measurements.

Conclusion:

Repeated measurements of in vivo 3D ¹H‐MRSI of the complete prostate at 1.5T produce equal and quantitative results. The reproducibility of the technique is high enough to provide it as a reliable tool in assessing tumor presence in the prostate. J. Magn. Reson. Imaging 2012;35:166‐173. © 2011 Wiley Periodicals, Inc.     

Lack of effect of oral choline supplement on the concentrations of choline metabolites in human brain

Recent reports suggest that oral choline supplement may alter the cerebral choline/creatine (Cho/Cr) ratio and might be used to treat neurodegenerative disorders of cholinergic transmission. Using both ¹H and ³¹P MRS, we reexamined the Cho/Cr ratio and quantified cerebral choline and its major constituents: phosphoethanolamine (PE), phosphorylcholine (PC), glycerophosphorylethanolamine (GPE), and glycero-phosphorylcholine (GPC). In the four brain locations examined, no significant increases in Cho/Cr, [Cho], or in its major constituents were found in response to an oral challenge of 50 mg/kg of choline bitartrate. Oral choline did not significantly affect human cerebral metabolism in the short term.     

A multicenter study of two magnetic resonance spectroscopy techniques in individuals with HIV dementia

PURPOSE: To evaluate single-voxel proton magnetic resonance spectroscopy (SV-MRS) and magnetic resonance spectroscopic imaging (MRSI) metabolite results in individuals with HIV dementia. MATERIALS AND METHODS: Twenty HIV-positive (HIV+) individuals underwent SV-MRS (TE 35 msec) and MRSI (TE 280 msec). Results were stratified according to serostatus, dementia severity, psychomotor speed performance, and functional impairment. RESULTS: HIV+ individuals with psychomotor slowing had an increased myoinositol/creatine (mI/Cr) ratio (0.63 vs. 0.45) in the frontal white matter using SV-MRS and an increased choline (Cho)/Cr ratio (1.88 vs. 1.41) in the mesial frontal gray matter using MRSI compared to HIV+ individuals without psychomotor slowing. Using MRSI, subjects with HIV dementia also had a decreased N-acetyl aspartate (NAA)/Cho ratio (1.55 vs. 2.53) compared to HIV+ individuals without cognitive impairment in the mesial frontal gray matter. Both techniques detected metabolite ratio abnormalities associated with abnormal functional performance. CONCLUSION: SV-MRS and MRSI offer complementary roles in evaluating individuals with HIV dementia. Short TE SV-MRS measures mI, which may be elevated in early HIV dementia, whereas MRSI provides wider spatial coverage to examine specific regional changes.