Prostate cancer: correlation of MR imaging and MR spectroscopy with pathologic findings after radiation therapy-initial experience

PURPOSE: To prospectively evaluate magnetic resonance (MR) imaging and MR spectroscopy for depiction of local prostate cancer recurrence after external-beam radiation therapy, with step-section pathologic findings as the standard of reference. MATERIALS AND METHODS: Study received institutional approval, and written informed consent was obtained. Study was compliant with Health Insurance Portability and Accountability Act. Sextant biopsy, digital rectal examination, MR imaging, MR spectroscopy, and salvage radical prostatectomy with step-section pathologic examination were performed in nine patients with increasing prostate-specific antigen levels after external-beam radiation therapy. MR imaging criterion for tumor was a focal nodular region of reduced signal intensity at T2-weighted imaging. MR spectroscopic criteria for tumor were voxels with choline (Cho) plus creatine (Cr) to citrate (Cit) ratio ([Cho + Cr]/Cit) of at least 0.5 or voxels with detectable Cho and no Cit in the peripheral zone. Sensitivity and specificity of sextant biopsy, digital rectal examination, MR imaging, and MR spectroscopy were determined by using a prostate sextant as the unit of analysis. For feature analysis, MR imaging and MR spectroscopic findings were correlated with step-section pathologic findings. RESULTS: MR imaging and MR spectroscopy showed estimated sensitivities of 68% and 77%, respectively, while sensitivities of biopsy and digital rectal examination were 48% and 16%, respectively. MR spectroscopy appears to be less specific (78%) than the other three tests, each of which had a specificity higher than 90%. MR spectroscopic feature analysis showed that a metabolically altered benign gland could be falsely identified as tumor by using MR spectroscopic criteria; further analysis of MR spectroscopic features did not lead to improved MR spectroscopic criteria for recurrent tumor. CONCLUSION: In summary, MR imaging and MR spectroscopy may be more sensitive than sextant biopsy and digital rectal examination for sextant localization of cancer recurrence after external-beam radiation therapy.     

Detection of prostate cancer with MR spectroscopic imaging: an expanded paradigm incorporating polyamines

PURPOSE: To characterize benign and malignant prostate peripheral zone (PZ) tissue retrospectively by using a commercial magnetic resonance (MR) spectroscopic imaging package and incorporating the choline plus creatine-to-citrate ratio ([Cho + Cr]/Cit) and polyamine (PA) information into a statistically based voxel classification procedure. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant study and waived the requirement for informed consent. Fifty men (median age, 60 years; range, 44-69 years) with untreated biopsy-proved prostate cancer underwent combined endorectal MR imaging and MR spectroscopic imaging. Commercial software was used to acquire and process MR spectroscopic imaging data. The (Cho + Cr)/Cit and the PA level were tabulated for each voxel. The PA level was scored on a scale of 0 (PA undetectable) to 2 (PA peak as high as or higher than Cho peak). Whole-mount step-section histopathologic analysis constituted the reference standard. Classification and regression tree analysis in a training set generated a decision-making tree (rule) for classifying voxels as malignant or benign, which was validated in a test set. Receiver operating characteristic and generalized estimating equation regression analyses were used to assess accuracy and sensitivity, respectively. RESULTS: The median (Cho + Cr)/Cit was 0.55 (mean +/- standard deviation, 0.59 +/- 0.03) in benign and 0.77 (mean, 1.08 +/- 0.20) in malignant PZ voxels (P = .027). A significantly higher percentage of benign (compared with malignant) voxels had higher PA than choline peaks (P < .001). In the 24-patient training set (584 voxels), the rule yielded 54% sensitivity and 91% specificity for cancer detection; in the 26-patient test set (667 voxels), it yielded 42% sensitivity and 85% specificity. The percentage of cancer in the voxel at histopathologic analysis correlated positively (P < .001) with the sensitivity of the classification and regression tree rule, which was 75% in voxels with more than 90% malignancy. CONCLUSION: The statistically based classification rule developed indicated that PAs have an important role in the detection of PZ prostate cancer. With commercial software, this method can be applied in clinical settings.     

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。     

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.     

Three-dimensional proton MR spectroscopy of human prostate at 3 T without endorectal coil: feasibility

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.     

Preoperative grading of gliomas by using metabolite quantification with high-spatial-resolution proton MR spectroscopic imaging

PURPOSE: To evaluate proton magnetic resonance (MR) spectroscopic imaging with high spatial resolution for preoperative grading of suspected World Health Organization grades II and III gliomas. MATERIALS AND METHODS: Institutional ethics committee approval and informed consent were obtained for control subjects but were not required for the retrospective component involving patients. Twenty-six patients (10 women, 16 men; mean age, 37.5 years) suspected of having gliomas and 26 age- and sex-matched control subjects underwent proton MR spectroscopy. Absolute metabolite concentrations for choline-containing compounds (Cho), creatine (Cr), and N-acetylaspartate (NAA)-N-acetylaspartylglutamate (total NAA [tNAA]) were calculated by using a user-independent spectral fit program. Metabolic maps of Cho/tNAA ratios were calculated, segmented, and used for MR spectroszpcopy-guided stereotactic brain biopsy. Two-sided paired Student t tests were used to test for statistical significance. RESULTS: Significantly lower Cho levels (P = .002) and higher tNAA levels (P = .010) were found in grade II tumors (n = 9) compared with grade III tumors (n = 17). The average Cho/tNAA ratio over the voxels in the tumor center showed a distinct difference (P < .001) between grade II and III gliomas at a threshold of 0.8 (with ratios <0.8 for grade II). The maximum Cr concentration in the tumor showed a clear-cut threshold between grade III oligodendrogliomas and oligoastrocytomas (Cr level, <7 mmol/L) and grade III astrocytomas (Cr level, >7 mmol/L; P = .020). Comparison between the histopathologic findings from the MR spectroscopy-guided biopsy samples (76 biopsies from 26 patients) and molar metabolite values in corresponding voxels located at the biopsy sampling points showed a negative linear correlation for tNAA (r = -0.905) and a positive exponential correlation for Cho (r = 0.769) and Cho/tNAA (r = 0.885). CONCLUSION: Proton MR spectroscopic imaging with high spatial resolution allows preoperative grading of gliomas.     

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     

中国健康成人前列腺3.0T体线圈磁共振波谱表现

目的探讨采用体线圈行前列腺3.0T磁共振波谱（MRS）检查的可行性,总结3D1H-MRS在正常前列腺中的表现。方法收集20名中老年健康志愿者行3.0T MRI常规检查、扩散加权成像及MRS检查。年龄为41～80岁,平均年龄（56±11）岁。MRS以体线圈为信号接收线圈,用Proseme序列进行扫描,体素分为正常外腺区、正常内腺区。然后工作软件自动计算每个体素的胆碱（Cho）相对值、（胆碱＋肌酸）/枸橼酸盐[（Cho＋Cr）/Cit]的比值。正常前列腺内、外腺分为左、右两侧,每侧由上到下分为底部、中部和尖部3部分,这样每个志愿者测量12个感兴趣区,每个感兴趣区包括0～3个可用体素平均计算。结果20名健康志愿者获得体素201个,其中可用体素170个（84.6%）,不可用体素为31个（15.4%）。20名中老年健康志愿者前列腺外腺区的（Cho＋Cr）/Cit平均值是0.39±0.21,内腺区的（Cho＋Cr）/Cit平均值是0.50±0.17,2组间比较差异有统计学意义（t=3.219,P〈0.01）。结论①用3.0T体线圈可以顺利完成对前列腺的MRS检查,并可以获得用于分析的体素,其在临床实践中具有可行性。②中老年正常前列腺内腺和外腺的代谢物含量是不同的,差异有统计学意义（t=3.219,P〈0.01）,内腺区（Cho＋Cr）/Cit平均值高于外腺区,进一步对其病变进行MRS定量研究时应根据解剖进行分区研究。     

Neuroimaging in pediatric brain tumors: Gd-DTPA-enhanced, hemodynamic, and diffusion MR imaging compared with MR spectroscopic imaging

BACKGROUND AND PURPOSE: Gadolinium-enhanced MR images assist in defining tumor borders; however, the relation between tumor cell extent and contrast-enhanced regions is unclear. Our aim was to improve conventional neuroimaging of pediatric brain tumors with hemodynamic, diffusion, and spectroscopic MR imaging. METHODS: We performed conventional MR and MR spectroscopic imaging in 31 children with neuroglial brain tumors. Hemodynamic MR imaging was performed in 16 patients with a first-pass intravenous bolus of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA); apparent diffusion coefficients (ADCs) were measured in 12 patients. To account for multiple measurements in a patient, we used a nested analysis of variance. RESULTS: At MR spectroscopy, choline (Cho)-containing compounds (indicating tumor) and lipid levels (indicating necrosis) did not correlate with percent Gd-DTPA enhancement on MR images. Percent enhancement was positively correlated with relative cerebral blood volumes (rCBVs) (P =.05) and negatively correlated with ADCs (P <.001). Stepwise multiple linear regression revealed that rCBV (P =.008), ADC (P =.022), and lipid (P <.001) levels were significant independent predictors of percent enhancement. Tumor spectral patterns were detected in tumor regions and outside enhancing tumor beds in patients with clinical progression; these were confirmed at neuropathologic analysis. CONCLUSION: MR spectroscopic imaging improves the assessment of pediatric brain tumors by adding biochemical information regarding tumor involvement and by depicting residual or recurrent tumor outside the Gd-DTPA-enhanced tumor bed. rCBV and ADC mapping complemented MR spectroscopic imaging. We recommend the use of MR spectroscopic imaging in addition to conventional MR imaging in assessing pediatric brain tumors.     

Metabolite ratios in 1H MR spectroscopic imaging of the prostate

In ¹H MR spectroscopic imaging (¹H‐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 ¹H‐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 ¹H‐MRSI. Magn Reson Med 73:1–12, 2015. © 2014 Wiley Periodicals, Inc.     

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%)。     

High-grade prostatic intraepithelial neoplasia in patients with prostate cancer: MR and MR spectroscopic imaging features--initial experience

PURPOSE: To retrospectively determine the magnetic resonance (MR) and MR spectroscopic imaging features of high-grade prostatic intraepithelial neoplasia (HGPIN) in patients with prostate cancer. MATERIALS AND METHODS: Approval of the committee on human research was obtained, with a waiver of consent for this HIPAA-compliant study. Endorectal MR imaging and MR spectroscopic imaging were performed in 48 men (mean age, 59 years; range, 47-75 years) prior to radical prostatectomy for prostate cancer. T2-weighted signal intensity and metabolic ratios of peripheral zone HGPIN foci of 6 mm or greater in diameter were recorded by two readers with knowledge of step-section histopathologic findings using areas of confirmed normal and cancerous peripheral zone tissue for comparison. A random effects statistical model was used to compare metabolic ratios from normal, HGPIN, and cancer voxels. RESULTS: A total of 123 peripheral zone HGPIN foci with a mean diameter of 3 mm (range, 1-28 mm) were identified in 37 (77%) patients, but only 20 foci in 14 patients had a diameter of 6 mm or greater. Six foci were excluded, yielding 14 large HGPIN lesions from 11 patients in the final statistical analysis. The larger HGPIN foci were not associated with any focal reduction in T2-weighted signal intensity but demonstrated metabolic findings intermediate between normal and cancerous tissue; the mean ratios of choline (Cho) to creatine (Cr) for normal, HGPIN, and cancer were 0.92, 1.75, and 1.99, respectively, (P < .01), and the corresponding ratios of Cho plus Cr to citrate were 0.34, 0.50, and 0.78 (P < .01). CONCLUSION: HGPIN is metabolically intermediate between normal peripheral zone tissue and prostate cancer at MR spectroscopic imaging but does not manifest any MR imaging abnormality and is rarely of sufficient size to cause substantial error in evaluation of peripheral zone tumor extent in patients with prostate cancer.     

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.     

Proton MR spectroscopy of the cerebellum and pons in patients with degenerative ataxia

PURPOSE: To investigate whether proton magnetic resonance (MR) spectroscopy is a useful complement to MR imaging in patients with degenerative ataxia. MATERIALS AND METHODS: Brain MR imaging and single-voxel proton MR spectroscopy of the right cerebellar hemisphere and pons were performed in 30 patients with sporadic (n = 16) or inherited (n = 14) degenerative ataxia and in 20 healthy control subjects. Several indexes of brainstem and cerebellar atrophy were measured on MR images, as well as the N-acetylaspartate/creatine (NAA/Cr), choline/Cr (Cho/Cr), and myo-inositol/Cr (mI/Cr) ratios in the MR spectra. Differences between patients and subjects were evaluated with the Kruskal-Wallis and Mann-Whitney tests, whereas correlation of clinical, MR imaging, and spectroscopic data was assessed with nonparametric Spearman rank correlation. RESULTS: Measurements of brainstem and cerebellar atrophy obtained from MR images revealed patients had olivopontocerebellar atrophy (OPCA) (n = 11), spinal atrophy (SA) (n = 8), or corticocerebellar atrophy (CCA) (n = 4). Seven patients did not fulfill the criteria for any group and were considered undefined. In patients with OPCA, the pontine and cerebellar NAA/Cr and Cho/Cr ratios were significantly decreased when compared with those of the control subjects. Pontine and cerebellar NAA/Cr ratios were also significantly reduced in patients with SA and CCA. Five patients with undefined ataxia had a substantial decrease of pontine or cerebellar NAA/Cr ratio when compared with that of the control subjects. In patients with OPCA, the pontine NAA/Cr ratio (but not the atrophy measurements) showed a correlation (P =.04) with disability. CONCLUSION: MR spectroscopy is a useful complement to MR imaging in patients with degenerative ataxia.     

Proton MR spectroscopic imaging depicts diffuse axonal injury in children with traumatic brain injury

BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) after traumatic brain injury (TBI) is important in patient assessment and prognosis, yet they are underestimated with conventional imaging techniques. We used MR spectroscopic imaging (MRSI) to detect DAI and determine whether metabolite ratios are accurate in predicting long-term outcomes and to examine regional differences in injury between children with TBI and control subjects. METHODS: Forty children with TBI underwent transverse proton MRSI through the level of the corpus callosum within 1-16 days after injury. T2-weighted, fluid-attenuated inversion recovery, and susceptibility-weighted MR imaging was used to identify voxels as normal-appearing or as nonhemorrhagic or hemorrhagic injury. Neurologic outcome was evaluated at 6-12 months after injury. Metabolite ratios for total (all voxels), normal-appearing, and hemorrhagic brain were compared and used in a logistic regression model to predict long-term outcome. Total and regional metabolite ratios were compared with control data. RESULTS: A significant decrease in N-acetylaspartate (NAA)/creatine (Cr) and increase in choline (Cho)/Cr (evidence of DAI) was observed in normal-appearing (P < .05) and visibly injured (hemorrhagic) brain (P < .001) compared with controls. In normal-appearing brain NAA/Cr decreased more in patients with poor outcomes (1.32 +/- 0.54) than in those with good outcomes (1.61 +/- 0.50, P = .01) or control subjects (1.86 +/- 0.1, P = .00). In visibly injured brains, ratios were similarly altered in all patients. In predicting outcomes, ratios from normal-appearing and visibly-injured brain were 85% and 67% accurate, respectively. CONCLUSION: MRSI can depict injury in brain that appears normal on imaging and is useful for predicting long-term outcomes.     

Proton magnetic resonance spectroscopic imaging in the border zone of gliomas: correlation of metabolic and histological changes at low tumor infiltration--initial results

PURPOSE: We sought to retrospectively investigate differences in correlation of absolute metabolites concentrations and metabolite ratios with histopathologic parameters of stereotactic biopsies from the border zone of gliomas. MATERIALS AND METHODS: Proton magnetic resonance spectroscopic imaging (H-MRSI) with high spatial resolution was performed in 10 glioma patients at 1.5 T. Magnetic resonance spectroscopic imaging (MRSI) data were coregistered to a 3D MR data set used for stereotactic procedures. Metabolite concentrations of choline-containing compounds (Cho), creatine (Cr), and total N-acetyl-aspartate (tNAA) in addition to metabolite ratios of Cho/Cr, tNAA/Cr, and Cho/tNAA were calculated for voxel positions at biopsy loci with low tumor cell infiltration. Metabolite values were correlated with histopathologic findings expressed as a relative (% tumor infiltration, %TI) and an absolute parameter (tumor cell number, TCN). RESULTS: We found a strong negative linear correlation for tNAA with %TI (R = -0.773, P < 0.001) and TCN (R = -0.769, P < 0.001) but no correlation for Cho (P > 0.05). On the other hand, the metabolite ratio of Cho/Cr showed a moderate positive linear correlation with %TI (R = 0.523, P = 0.012) and TCN (R = 0.486, P = 0.019), but no correlation was obtained for tNAA/Cr (P > 0.05). Differences in correlation between tNAA and Cho as well as tNAA/Cr and Cho/Cr were significant for both %TI (P = 0.012 and P = 0.024) and TCN (P = 0.016 and P = 0.040) using a t test. CONCLUSIONS: We conclude that absolute values of tNAA are more significant than Cho in the detection of low tumor cell infiltration. On the basis of absolute metabolite values, neuronal damage seems to be more distinct than cell membrane proliferation in the border zone of gliomas. Furthermore, the calculation of metabolite ratios versus Cr for the border zone may yield to misleading results because Cr is not constant in this area.     

Early- and late-state subacute sclerosing panencephalitis: chemical shift imaging and single-voxel MR spectroscopy

BACKGROUND AND PURPOSE: Subacute sclerosing panencephalitis (SSPE) is a rare, progressive, inflammatory neurodegenerative disease. Our aim was to determine the metabolic abnormalities of brain in early- and late-stage SSPE by using MR spectroscopy and to assess areas of involvement in the early stages when MR imaging findings were normal. METHODS: Children with stage II (n = 3) or III (n = 3) SSPE and 10 healthy, age-matched children underwent MR imaging, multivoxel MR spectroscopy, and short-echo single-voxel MR spectroscopy (SVS). Areas of involvement in the brain were determined with chemical shift imaging. For SVS, 2 x 2 x 2-cm voxels were placed in the frontal subcortical white matter (FSWM) and parieto-occipital white matter (POWM). N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (Ins)/Cr, and NAA/Cho ratios were calculated. RESULTS: Comparisons of NAA/Cr, Cho/Cr, Ins/Cr and NAA/Cho ratios between patients and control subjects showed significant differences in FSWM and POWM (P <.01). In patients with SSPE, NAA/Cr ratios in POWM were significantly less than those in FSWM (P <.01). NAA/Cr ratios in patients with stage II SSPE and those in the control group were not significantly different; this may reflect the absence of neuronal loss. Decreased NAA/Cr, increased Cho/Cr and Ins/Cr ratios, and increased lactate and lipid peaks were found in patients with stage III SSPE. CONCLUSION: MR spectroscopy showed findings suggestive of inflammation in stage II and findings of demyelination, gliosis, cellular necrosis, and anaerobic metabolism in stage III. MR spectroscopy could be a promising technique for early diagnosis and treatment planning in cases of SSPE.     

Three-dimensional multivoxel proton MR spectroscopy of the brain in children with neurofibromatosis type 1.

BACKGROUND AND PURPOSE: Neurofibromatosis type 1 (NF1), the most common autosomal dominant genetic disorder, frequently manifests as focal areas of signal intensity (FASI) on T2-weighted MR images. The purpose of our study was to investigate whether tumor(s), focal areas of signal intensity (FASI), and normal brain can be differentiated by using 3D multivoxel localized proton MR spectroscopy in children with neurofibromatosis type 1 (NF1) disorder. METHODS: Five children with NF1 and two healthy control subjects, all in the 3- to 11-year-old age group, were studied with a new 3D proton MR spectroscopy technique: a hybrid of 1D fourth-order transverse Hadamard spectroscopic imaging and 2D chemical shift imaging. A 3D volume-of-interest (VOI) was image-guided onto the site of the abnormality and identified on three orthogonal images. Proton MR spectroscopy partitioned the VOI into 6 x 6 x 4 (or 8 x 8 x 4) voxels, 1.5 (or 1.0) cm3 each. RESULTS: Simultaneous coverage of the entire VOI yielded good spectral signal-to-noise ratio from 136 (or 256) voxels in 27 minutes. Proton MR spectroscopy indicated that FASI a) are characterized by significantly elevated choline (Cho), reduced creatine (Cr), 2>Cho: Cr>1.3, and near normal N-acetylaspartate (NAA) levels; b) are different from tumors that exhibit Cho:Cr>2 and no NAA; c) have no intrinsic lipid or lactate signal(s); and d) correlate in spatial extent but are more extensive than indicated by MR imaging. CONCLUSION: Three-dimensional multivoxel proton MR spectroscopy reveals distinct metabolic features that differentiate normal, FASI, and tumor regions in the pediatric brain.     

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.     

Relationships between astrogliosis and 1H MR spectroscopic measures of brain choline/creatine and myo-inositol/creatine in a primate model

BACKGROUND AND PURPOSE: In vivo 1H MR spectroscopy demonstrates elevated choline (Cho)/creatine (Cr) and myo-inositol (MI)/Cr in many neurologic diseases that has been ascribed to gliosis. We tested the hypotheses that in vivo Cho/Cr and/or MI/Cr levels are correlated with glial fibrillary acidic protein (GFAP) immunostains and that the changes are water-soluble metabolites. METHODS: We performed postmortem 1H MR spectroscopy and GFAP immunohistochemistry in brains from seven rhesus macaques acutely infected with simian immunodeficiency virus (SIV) and in four controls and compared the findings with previous in vivo MR spectroscopic results. Changes in neuropathologic and MR spectroscopic markers after infection and relationships among plasma viral load, GFAP immunostaining results, and ex vivo and in vivo MR spectroscopic measures were statistically evaluated. RESULTS: On GFAP immunostaining and in vivo MR spectroscopy, GFAP, Cho/Cr and MI/Cr were highest near the time of peak plasma viral load at 11 days postinfection (dpi). Immunostains returned to baseline by 14 dpi, whereas Cho/Cr and MI/Cr had different time courses, with the former dropping below baseline and the latter remaining elevated. Viral load and immunostains were significantly correlated. No correlation was found between ex vivo Cho/Cr or MI/Cr and viral load or between metabolite ratios from in vivo and ex vivo MR spectroscopy. CONCLUSION: In acute SIV infection, plasma viral load was significantly correlated with brain GFAP immunostains and in vivo 1H MR spectroscopic Cho/Cr. In vivo changes in Cho/Cr and MI/Cr were principally due to contributions other than those of low-molecular-weight water-soluble metabolites.