Proton magnetic resonance spectroscopy of brain tumors: an in vitro study

Imaging findings of right-sided trigone intraventricular meningioma: A case report

Intraventricular meningioma is a case with an incidence about 0.5%-2% of all cases of meningioma. About 80% of all intraventricular meningiomas occur in the trigone of lateral ventricle and more common on the left side. In this case, we present a 43-year-old woman with Right-sided Trigone Intraventricular Meningioma. The diagnosis and assessment of intraventricular meningiomas remains a challenge. Radiological examination has a major role in cases of intraventricular meningioma. Presurgical diagnostic imaging may be useful in corroborating the diagnosis. In this article, we describe the patients with intraventricular meningiomas in CT and MR imaging that revealed useful data for diagnosis.

Amino acids profile within peripheral blood and follicular fluid based on high-performance liquid chromatography methods may explain differences in folliculogenesis between short-term under/over-fed treatments during luteal phase of Hu sheep

The nutritional alteration of amino acids (AAs) profile in physiological fluid was poorly characterized in livestock. After oestrus synchronization, 24 ewes were randomly assigned to two groups based on the nutrient requirement recommended for maintenance (M): the feed-supplemented group (S, 1.5 × M, N = 12) and feed-restricted group (R, 0.5 × M, N = 12) on days 6-12 of their oestrous cycle, which occurred shortly before ovulation. The concentration of 30 AAs in peripheral blood (PB) and follicular fluid (FF) was quantified to calculate the PB-to-FF concentration gap for each AA and determine its correlation with metabolites and hormones in PB and FF. Results showed that the feed restriction enlarged the oestrous cycle length, decreased the number of follicles 2.5-3.5 mm, increased the number of follicles >3.5 mm and augmented the volume of follicles >2.5 mm. Nineteen AAs from PB were significantly different between the groups. The phosphoethanolamine (PEtN) and ration of essential AAs to nonessential AAs (EAA/NEAA) in FF significantly (p < 0.05) increased and decreased in the R group, respectively. Most AAs, except aspartate (Asp) and carnosine (Car) in the R group and alanine (aAla) in both groups, were significantly lower within FF than those within PB. The correlation of AAs with FSH and progesterone (P₄ ) was more significant than that of AAs with other endocrine milieu characteristics. In conclusion, our results revealed that the influence of short-term nutritional manipulation during luteal phase on folliculogenesis might not be due to the variation of intrafollicular AAs profile but rather attribute to the peripheral blood AAs profile alteration.

Glycine: a non-invasive imaging biomarker to aid magnetic resonance spectroscopy in the prediction of survival in paediatric brain tumours

Paediatric brain tumours have a high mortality rate and are the most common solid tumour of childhood. Identification of high risk patients may allow for better treatment stratification. Magnetic Resonance Spectroscopy (MRS) provides a non-invasive measure of brain tumour metabolism and quantifies metabolite survival markers to aid in the clinical management of patients. Glycine can be identified using MRS and has been recently found to be important for cancer cell proliferation in tumours making it a valuable prognostic marker. The aims of this study were to investigate glycine and its added value to MRS as a prognostic marker for paediatric brain tumours in a clinical setting.

116 children with newly diagnosed brain tumours were examined with short echo-time MRS at the Birmingham Children’s Hospital and followed up for five years. Survival analysis was performed using Cox regression on the entire metabolite basis set with focus on glycine and three other established survival markers for comparison: n-acetylaspartate, scyllo-inositol and lipids at 1.3 ppm. Multivariate Cox regression was used in conjunction with risk values to establish if glycine added prognostic power when combined to the established survival markers.

Glycine was found to be a marker of poor prognosis in the cohort (p < 0.05) and correlated with tumour grade (p < 0.01). The addition of glycine improved the prognostic power of MRS compared to using the combination of established survival markers alone.

Tumour glycine was found to improve the MRS prediction of reduced survival in paediatric brain tumours aiding the non-invasive assessment of these children.

Metabolomics-A Promising Approach to Pituitary Adenomas

Background: Metabolomics-the novel science that evaluates the multitude of low-molecular-weight metabolites in a biological system, provides new data on pathogenic mechanisms of diseases, including endocrine tumors. Although development of metabolomic profiling in pituitary disorders is at an early stage, it seems to be a promising approach in the near future in identifying specific disease biomarkers and understanding cellular signaling networks. Objectives: To review the metabolomic profile and the contributions of metabolomics in pituitary adenomas (PA). Methods: A systematic review was conducted via PubMed, Web of Science Core Collection and Scopus databases, summarizing studies that have described metabolomic aspects of PA. Results: Liquid chromatography tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) spectrometry, which are traditional techniques employed in metabolomics, suggest amino acids metabolism appears to be primarily altered in PA. N-acetyl aspartate, choline-containing compounds and creatine appear as highly effective in differentiating PA from healthy tissue. Deoxycholic and 4-pyridoxic acids, 3-methyladipate, short chain fatty acids and glucose-6-phosphate unveil metabolite biomarkers in patients with Cushing's disease. Phosphoethanolamine, N-acetyl aspartate and myo-inositol are down regulated in prolactinoma, whereas aspartate, glutamate and glutamine are up regulated. Phosphoethanolamine, taurine, alanine, choline-containing compounds, homocysteine, and methionine were up regulated in unclassified PA across studies. Intraoperative use of ultra high mass resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), which allows localization and delineation between functional PA and healthy pituitary tissue, may contribute to achievement of complete tumor resection in addition to preservation of pituitary cell lines and vasopressin secretory cells, thus avoiding postoperative diabetes insipidus. Conclusion: Implementation of ultra high performance metabolomics analysis techniques in the study of PA will significantly improve diagnosis and, potentially, the therapeutic approach, by identifying highly specific disease biomarkers in addition to novel molecular pathogenic mechanisms. Ultra high mass resolution MALDI-MSI emerges as a helpful clinical tool in the neurosurgical treatment of pituitary tumors. Therefore, metabolomics appears to be a science with a promising prospect in the sphere of PA, and a starting point in pituitary care.

Primary Intracranial Extra-Axial Anaplastic Ependymomas

BACKGROUND

Ependymomas are usually located in the ventricular system or in the central canal of the spinal cord; intracranial extra-axial ependymomas (IEAEs) are rare. To date, only 17 cases of IEAEs have been reported.

CASE DESCRIPTION

We report 2 cases with 3 IEAEs (anaplastic) that were initially misdiagnosed. In Case 1 (47-year-old male), the para-falcine lesion was initially refractory to radiosurgery and gross total resection (GTR) was required due to relentless growth. The lesion had adhered to the falx and was well demarcated from the surrounding cortex. It was then correctly diagnosed as an anaplastic ependymoma on the basis of histopathology, and the patient received radiotherapy. No recurrence was observed after the 53-month follow-up. In Case 2 (30-year-old male), 2 IEAEs underwent staged surgeries and were identified as extra-axial lesions without connection to the ventricular system. Near total resection (NTR) and GTR were achieved in the right temporal and right occipital lesions, respectively, but the patient declined radiotherapy. The residual tumor after NTR regrew rapidly, and aggressive resection was performed followed by radiotherapy. No further recurrence was observed after 28 months. The previous 17 cases were male predominant (76.5%) without correct preoperative diagnoses; no recurrence was observed after total resection in the 9 patients reported in the literature.

CONCLUSIONS

IEAEs are rare and have a wide spectrum of clinical and radiological phenotypes. Preoperative diagnosis is difficult. Favorable outcomes for IEAEs can be achieved by GTR plus radiotherapy. Multiple IEAEs benefit from tailored staged surgical resection plus radiotherapy.

Advanced Imaging of Intracranial Meningiomas

Although typically not necessary for the diagnosis of intracranial meningiomas, advanced imaging techniques, including perfusion and diffusion imaging, spectroscopy, and nuclear medicine imaging, can help confirm the diagnosis of intracranial meningiomas, especially for meningiomas that do not exhibit the typical anatomic imaging findings. Advanced imaging techniques also have the potential to be able to differentiate between the subtypes of meningiomas, predict clinical aggressiveness of the tumor, and better characterize response to treatment. Although no advanced imaging technique has been able to definitively subclassify meningiomas, current results are encouraging and may be helpful in surgical planning.

Intracranial cystic meningiomas: A rare type of tumours

INTRODUCTION

Intracranial cystic meningiomas are rare and preoperative diagnosis is difficult. The present study was performed to assess the clinical and radiological outcome of intracranial cystic meningiomas.

METHODS

We performed a retrospective analysis of 13 patients (mean age: 49.9 years) who underwent surgical resection of intracranial cystic meningiomas from January 2006 to February 2014. There were 5 male and 8 female patients. The Glasgow Outcome Scale was used to assess the clinical outcome at 6 months.

RESULTS

Headache was the main presenting clinical feature. Most of the tumours were located on the right side. The frontal convexity was the most common site. Gross total resection was performed in 10 patients. The most common histopathological type was meningothelial variety.

CONCLUSION

Intracranial cystic meningiomas are usually benign that occur in relatively young patients. Resection of cysts that show contrast enhancement is essential to reduce recurrence.

[Interdisciplinary neuro-oncology: part 1: diagnostics and operative therapy of primary brain tumors]

By combining the expertise of clinical neuroscience, the aim of neuro-oncology is to optimize diagnostic planning and therapy of primary brain tumors in an interdisciplinary setting together with radio-oncology and medical oncology. High-end imaging frequently allows brain tumors to be diagnosed preoperatively with respect to tumor entity and even tumor malignancy grade. Moreover, neuroimaging is indispensable for guidance of biopsy resection and monitoring of therapy. Surgical resection of intracranial lesions with preservation of neurological function is increasingly feasible. Tools to achieve this goal are, for example neuronavigation, functional magnetic resonance imaging (fMRI), tractography, intraoperative cortical stimulation and precise intraoperative definition of tumor margins by virtue of various techniques. In addition to classical histopathological diagnosis and tumor classification, modern neuropathology is supplemented by molecular characterization of brain tumors in order to provide clinicians with prognostic and predictive (of therapy) markers, such as codeletion of chromosomes 1p and 19q in anaplastic gliomas and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation in glioblastomas. Although this is not yet individualized tumor therapy, the increasingly more detailed analysis of the molecular pathogenesis of an individual glioma will eventually lead to specific pharmacological blockade of disturbed intracellular pathways in individual patients. This article gives an overview of the state of the art of interdisciplinary neuro-oncology whereby part 1 deals with the diagnostics and surgical therapy of primary brain tumors and part 2 describes the medical therapy of primary brain tumors.

Insular cortex metabolite changes in obstructive sleep apnea

STUDY OBJECTIVE

Adults with obstructive sleep apnea (OSA) show significant autonomic and neuropsychologic deficits, which may derive from damage to insular regions that serve those functions. The aim was to assess glial and neuronal status from anterior insular metabolites in OSA versus controls, using proton magnetic resonance spectroscopy (PMRS), and thus to provide insights for neuroprotection against tissue changes, and to reduce injury consequences.

DESIGN

Cross-sectional study.

SETTING

University-based medical center.

PARTICIPANTS

Thirty-six patients with OSA, 53 controls.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

We performed PMRS in bilateral anterior insulae using a 3.0-Tesla magnetic resonance imaging scanner, calculated N-acetylaspartate/creatine (NAA/Cr), choline/creatine (Cho/Cr), myo-inositol/creatine (MI/Cr), and MI/NAA metabolite ratios, and examined daytime sleepiness (Epworth Sleepiness Scale, ESS), sleep quality (Pittsburgh Sleep Quality Index, PSQI), and neuropsychologic status (Beck Depression Inventory II [BDI-II] and Beck Anxiety Inventory [BAI]). Body mass index, BAI, BDI-II, PSQI, and ESS significantly differed between groups. NAA/ Cr ratios were significantly reduced bilaterally, and left-sided MI/Cr and MI/NAA ratios were increased in OSA over controls. Significant positive correlations emerged between left insular MI/Cr ratios and apnea-hypopnea index values, right insular Cho/Cr ratios and BDI-II and BAI scores, and negative correlations appeared between left insular NAA/Cr ratios and PSQI scores and between right-side MI/Cr ratios and baseline and nadir change in O2 saturation.

CONCLUSIONS

Adults with obstructive sleep apnea showed bilaterally reduced N-acetylaspartate and left-side increased myo-inositol anterior insular metabolites, indicating neuronal damage and increased glial activation, respectively, which may contribute to abnormal autonomic and neuropsychologic functions in the condition. The activated glial status likely indicates increased inflammatory action that may induce more neuronal injury, and suggests separate approaches for glial and neuronal protection.

High-resolution NMR spectroscopy of human body fluids and tissues in relation to prostate cancer

High-resolution NMR spectroscopic studies of prostate tissue extracts, prostatic fluid, seminal fluid, serum and urine can be used for the detection of prostate cancer, based on the differences in their metabolic profiles. Useful diagnostic information is obtained by the detection or quantification of as many metabolites as possible and comparison with normal samples. Only a few studies have shown the potential of high-resolution in vitro NMR of prostate tissues. A survey of the literature has revealed that studies on body fluids, such as urine and serum, in relation to prostate cancer are rare. In addition, the potential of NMR of nuclei other than (1)H, such as (13)C and (31)P, has not been exploited fully. The metabolomic analysis of metabolites, detected by high-resolution NMR, may help to identify metabolites which could serve as useful biomarkers for prostate cancer detection. Such NMR-derived biomarkers would not only help in prostate cancer detection and in understanding the in vivo MRS metabolic profile, but also to investigate the biochemical and metabolic changes associated with cancer. Here, we review the published research work on body fluids in relation to prostate and prostate tissue extracts, and highlight the potential of such studies for future work.

High-resolution magic angle spinning (1)H magnetic resonance spectroscopy detects choline as a biomarker in a swine obstructive chronic pancreatitis model at an early stage

Chronic pancreatitis (CP) is a progressive inflammatory and fibrotic disease of the pancreas which encompasses a variety of clinical syndromes ranging from mild to life-threatening complications. Metabolomics has increasingly been applied to identify biomarkers for disease diagnosis with particular interest in diseases at an early stage. In this study, we tested a swine obstructive CP model by subtotal ligation of the main pancreatic duct, and the metabolic profiles of the Bama miniature swine pancreas were investigated using high-resolution magic angle spinning proton magnetic resonance spectroscopy (HR MAS (1)H MRS) combined with principal components analysis (PCA). Increases in lactate and choline for mild CP and decreases in glycerophosphocholine, phosphocholine, betaine and glycine were observed from normal pancreas to mild, moderate and severe CP. PCA results showed visual separations among the groups. The increase of choline at an early stage of CP and the decrease of glycerophosphocholine, phosphocholine, betaine and glycine reveal the pathogenesis of CP at a molecular level. The MRS results presented here demonstrate the potential of metabolic profiles in discriminating a normal pancreas from different stages of CP, which may be used to achieve CP early diagnosis and timely intervention to prevent irreversible destruction of the pancreas.

Correlating magnetic resonance findings with neuropathology and clinical signs in dogs and cats

The histologic characteristics that are the basis for diagnosis of central nervous system conditions cannot be visualized directly using magnetic resonance (MR) methods, but clinical diagnosis may be based on the frequency and pattern of MR imaging signs, which represent predominantly the gross morphologic features of lesions. Additional quantitative MR measures of myelination, cell swelling, gliosis, and neuronal loss may also be used for more specific characterization of lesions. These measures include magnetization transfer ratio, apparent diffusion coefficient, and the concentrations or ratios of metabolites identified by spectroscopy. Confidence that an MR abnormality is responsible for the clinical signs depends primarily on the degree of correspondence between the site of the lesion and the neuroanatomical localization.

Effects of electromagnetic radiation produced by 3G mobile phones on rat brains: Magnetic resonance spectroscopy, biochemical, and histopathological evaluation

Objective: The effects of electromagnetic radiation (EMR) produced by a third-generation (3G) mobile phone (MP) on rat brain tissues were investigated in terms of magnetic resonance spectroscopy (MRS), biochemistry, and histopathological evaluations. Methods: The rats were randomly assigned to two groups: Group 1 is composed of 3G-EMR-exposed rats ( n = 9) and Group 2 is the control group ( n = 9). The first group was subjected to EMR for 20 days. The control group was not exposed to EMR. Choline (Cho), creatinin (Cr), and N-acetylaspartate (NAA) levels were evaluated by MRS. Catalase (CAT) and glutathione peroxidase (GSH-Px) enzyme activities were measured by spectrophotometric method. Histopathological analyses were carried out to evaluate apoptosis in the brain tissues of both groups. Results: In MRS, NAA/Cr, Cho/Cr, and NAA/Cho ratios were not significantly different between Groups 1 and 2. Neither the oxidative stress parameters, CAT and GSH-Px, nor the number of apoptotic cells were significantly different between Groups 1 and 2. Conclusions: Usage of short-term 3G MP does not seem to have a harmful effect on rat brain tissue.

Metabolomic patterns in glioblastoma and changes during radiotherapy: a clinical microdialysis study

We employed stereotactic microdialysis to sample extracellular fluid intracranially from glioblastoma patients, before and during the first five days of conventional radiotherapy treatment. Microdialysis catheters were implanted in the contrast enhancing tumor as well as in the brain adjacent to tumor (BAT). Reference samples were collected subcutaneously from the patients' abdomen. The samples were analyzed by gas chromatography-time-of-flight mass spectrometry (GC-TOF MS), and the acquired data was processed by hierarchical multivariate curve resolution (H-MCR) and analyzed with orthogonal partial least-squares (OPLS). To enable detection of treatment-induced alterations, the data was processed by individual treatment over time (ITOT) normalization. One-hundred fifty-one metabolites were reliably detected, of which 67 were identified. We found distinct metabolic differences between the intracranially collected samples from tumor and the BAT region. There was also a marked difference between the intracranially and the subcutaneously collected samples. Furthermore, we observed systematic metabolic changes induced by radiotherapy treatment among both tumor and BAT samples. The metabolite patterns affected by treatment were different between tumor and BAT, both containing highly discriminating information, ROC values of 0.896 and 0.821, respectively. Our findings contribute to increased molecular knowledge of basic glioblastoma pathophysiology and point to the possibility of detecting metabolic marker patterns associated to early treatment response.

High-resolution magic angle spinning magnetic resonance spectroscopy detects glycine as a biomarker in brain tumors

The non-essential amino acid neurotransmitter glycine (Gly) may serve as a biomarker for brain tumors. Using 36 biopsies from patients with brain tumors [12 glioblastoma multiforme (GBM); 10 low-grade (LG), including 7 schwannoma and 3 pylocytic astrocytoma; 7 meningioma (MN); 7 brain metastases (MT), including 3 adenocarcinoma and 4 breast cancer] and 9 control biopsies from patients undergoing surgery for epilepsy, we tested the hypothesis that the presence of glycine may distinguish among these brain tumor types. Using high-resolution magic angle spinning (HRMAS) ¹H magnetic resonance spectroscopy (MRS), we determined a theoretically optimum echo time (TE) of 50 ms for distinguishing Gly signals from overlapping myo-inositol (Myo) signals and tested our methodology in phantom and biopsy specimens. Quantitative analysis revealed higher levels of Gly in tumor biopsies (all combined) relative to controls; Gly levels were significantly elevated in LG, MT and GBM biopsies (P≤0.05). Residual Myo levels were elevated in LG and MT and reduced in MN and GBM (P<0.05 vs. control levels). We observed higher levels of Gly in GBM as compared to LG tumors (P=0.05). Meanwhile, although Gly levels in GBM and MT did not differ significantly from each other, the Gly:Myo ratio did distinguish GBM from MT (P<0.003) and from all other groups, a distinction that has not been adequately made previously. We conclude from these findings that Gly can serve as a biomarker for brain tumors and that the Gly:Myo ratio may be a useful index for brain tumor classification.

Using ex vivo proton magnetic resonance spectroscopy to reveal associations between biochemical and biological features of meningiomas

Object

The goal in this study was to determine if proton (1H) MR spectroscopy can differentiate meningioma grade and is associated with interpretations of biological behavior; the study was performed using ex vivo high-resolution spectra indicating metabolic characteristics.

Methods

Sixty-eight resected tissue samples of meningiomas were examined using ex vivo 1H MR spectroscopy. Of these meningiomas, 46 were WHO Grade I, 14 were WHO Grade II, and 8 were WHO Grade III. Fifty-nine were primary meningiomas and 9 were recurrences. Invasion of adjacent tissue (dura mater, bone, venous sinus, brain) was found in 32 cases. Thirty-nine meningiomas did not rapidly recur (as defined by expansion on MR imaging within a 5-year follow-up period), whereas rapid recurrence was confirmed in 24 meningiomas, and follow-up status was unknown in 5 cases.

Results

The absolute concentrations of total alanine and creatine were decreased in high-grade compared with low-grade meningiomas, as was the ratio of glycine to alanine (all p < 0.05). Additionally, alanine and the glycine/alanine ratio distinguished between primary and recurrent meningiomas (all p < 0.05). Finally, the absolute concentrations of alanine and creatine, and the glycine/alanine and choline/glutamate ratios were associated with rapid recurrence (p < 0.05).

Conclusions

. These data indicate that meningioma tissue can be characterized by metabolic parameters that are not typically identified by histopathological analysis alone. Creatine, glycine, and alanine may be used as markers of meningioma grade, recurrence, and the likelihood of rapid recurrence. These data validate a previous study of a separate group of Grade I meningiomas.

Non-invasive detection of glycine as a biomarker of malignancy in childhood brain tumours using in-vivo 1H MRS at 1.5 tesla confirmed by ex-vivo high-resolution magic-angle spinning NMR

Management of brain tumours in children would benefit from improved non-invasive diagnosis, characterisation and prognostic biomarkers. Metabolite profiles derived from in-vivo MRS have been shown to provide such information. Studies indicate that using optimum a priori information on metabolite contents in the construction of linear combination (LC) models of MR spectra leads to improved metabolite profile estimation. Glycine (Gly) is usually neglected in such models due to strong overlap with myo-inositol (mI) and a low concentration in normal brain. However, biological studies indicate that Gly is abundant in high-grade brain tumours. This study aimed to investigate the quantitation of Gly in paediatric brain tumours using MRS analysed by LCModel, and its potential as a non-invasive biomarker of malignancy. Single-voxel MRS was performed using PRESS (TR 1500 ms, TE 30 ms/135 ms) on a 1.5 T scanner. Forty-seven cases (18 high grade (HG), 17 low grade (LG), 12 ungraded) were retrospectively selected if both short-TE and long-TE MRS (n = 33) or short-TE MRS and high-resolution magic-angle spinning (HRMAS) of matched surgical samples (n = 15) were available. The inclusion of Gly in LCModel analyses led to significantly reduced fit residues for both short-TE and long-TE MRS (p < 0.05). The Gly concentrations estimated from short-TE MRS were significantly correlated with the long-TE values (R = 0.91, p < 0.001). The Gly concentration estimated by LCModel was significantly higher in HG versus LG tumours for both short-TE (p < 1e-6) and long-TE (p = 0.003) MRS. This was consistent with the HRMAS results, which showed a significantly higher normalised Gly concentration in HG tumours (p < 0.05) and a significant correlation with the normalised Gly concentration measured from short-TE in-vivo MRS (p < 0.05). This study suggests that glycine can be reliably detected in paediatric brain tumours using in-vivo MRS on standard clinical scanners and that it is a promising biomarker of tumour aggressiveness.

1H HR-MAS and genomic analysis of human tumor biopsies discriminate between high and low grade astrocytomas

We investigate the profile of choline metabolites and the expression of the genes of the Kennedy pathway in biopsies of human gliomas (n = 23) using (1)H High Resolution Magic Angle Spinning (HR-MAS, 11.7 Tesla, 277 K, 4000 Hz) and individual genetic assays. (1)H HR-MAS spectra allowed the resolution and relative quantification by the LCModel of the resonances from choline (Cho), phosphocholine (PC) and glycerophosphorylcholine (GPC), the three main components of the combined tCho peak observed in gliomas by in vivo (1)H NMR spectroscopy. All glioma biopsies depicted a prominent tCho peak. However, the relative contributions of Cho, PC, and GPC to tCho were different for low and high grade gliomas. Whereas GPC is the main component in low grade gliomas, the high grade gliomas show a dominant contribution of PC. This circumstance allowed the discrimination of high and low grade gliomas by (1)H HR-MAS, a result that could not be obtained using the tCho/Cr ratio commonly used by in vivo (1)H NMR spectroscopy. The expression of the genes involved in choline metabolism has been investigated in the same biopsies. High grade gliomas depict an upregulation of the beta gene of choline kinase and phospholipase C, as well as a downregulation of the cytidyltransferase B gene, the balance of these being consistent with the accumulation of PC. In the low grade gliomas, phospholipase A(1) and lysophospholipase are upregulated and phospholipase D is downregulated, supporting the accumulation of GPC. The present findings offer a promising procedure that will potentially help to accurately grade glioma tumors using (1)H HR-MAS, providing in addition the genetic background for the alterations of choline metabolism observed in high and low grade gliomas.

In vivo 1H NMR measurement of glycine in rat brain at 9.4 T at short echo time

Glycine is an amino acid present in mammalian brain, where it acts as an inhibitory and excitatory neurotransmitter. The two detectable protons of glycine give rise to a singlet at 3.55 ppm that overlaps with the more intense myo-inositol resonances, and its measurement has traditionally required specific editing efforts. The aim of the current study was to reduce the signal intensity of myo-inositol relative to that of glycine by exploiting the fast signal J-evolution of the myo-inositol spin system when using a single spin-echo localization method we recently introduced. Glycine was detected at TE = 20 ms with an average Cramér-Rao lower bound (CRLB) of 8.6% +/- 1.5% in rat brain (N = 5), at 9.4 T. The concentration of glycine was determined using LCModel analysis at 1.1 +/- 0.1 mM, in good agreement with biochemical measurements previously reported. We conclude that at high magnetic fields, glycine can be measured at a relatively short echo time (TE) without additional editing efforts.

Meningiomas of the lateral ventricles. A review of 10 cases

BACKGROUND

Intraventricular meningiomas are rare tumours that represent about 2% of all intracranial meningiomas, and represent one of the most challenging problems in neurosurgery. They are located deep within the brain and often are sizable and highly vascular. We report on a series of 10 meningiomas of the lateral ventricles treated at our institution during the last 28 years.

PATIENTS

Ten patients (6 women, 4 men; mean age 41.6 yrs) were admitted to our medical center between 1978-2005 with meningioma of the lateral ventricles. Headache was the first symptom in 8 cases and ocular signs were present in 5 patients.

RESULTS

Seven tumours were located in the right ventricle (70%) ranging in size from 2-8 cm, with 7 tumours larger than 3 cm in diameter. Nine patients underwent surgery with total excision in 8 cases and subtotal in the other; the remaining patient only received radiosurgery.

CONCLUSIONS

Total resection is the gold standard for treatment which was possible in all but one of the cases undergoing surgery.

Molecular classification of brain tumor biopsies using solid-state magic angle spinning proton magnetic resonance spectroscopy and robust classifiers

Brain tumors are one of the leading causes of death in adults with cancer; however, molecular classification of these tumors with in vivo magnetic resonance spectroscopy (MRS) is limited because of the small number of metabolites detected. In vitro MRS provides highly informative biomarker profiles at higher fields, but also consumes the sample so that it is unavailable for subsequent analysis. In contrast, ex vivo high-resolution magic angle spinning (HRMAS) MRS conserves the sample but requires large samples and can pose technical challenges for producing accurate data, depending on the sample testing temperature. We developed a novel approach that combines a two-dimensional (2D), solid-state, HRMAS proton (1H) NMR method, TOBSY (total through-bond spectroscopy), which maximizes the advantages of HRMAS and a robust classification strategy. We used approximately 2 mg of tissue at -8 degrees C from each of 55 brain biopsies, and reliably detected 16 different biologically relevant molecular species. We compared two classification strategies, the support vector machine (SVM) classifier and a feed-forward neural network using the Levenberg-Marquardt back-propagation algorithm. We used the minimum redundancy/maximum relevance (MRMR) method as a powerful feature-selection scheme along with the SVM classifier. We suggest that molecular characterization of brain tumors based on highly informative 2D MRS should enable us to type and prognose even inoperable patients with high accuracy in vivo.

The effect of combining two echo times in automatic brain tumor classification by MRS

(1)H MRS is becoming an accurate, non-invasive technique for initial examination of brain masses. We investigated if the combination of single-voxel (1)H MRS at 1.5 T at two different (TEs), short TE (PRESS or STEAM, 20-32 ms) and long TE (PRESS, 135-136 ms), improves the classification of brain tumors over using only one echo TE. A clinically validated dataset of 50 low-grade meningiomas, 105 aggressive tumors (glioblastoma and metastasis), and 30 low-grade glial tumors (astrocytomas grade II, oligodendrogliomas and oligoastrocytomas) was used to fit predictive models based on the combination of features from short-TEs and long-TE spectra. A new approach that combines the two consecutively was used to produce a single data vector from which relevant features of the two TE spectra could be extracted by means of three algorithms: stepwise, reliefF, and principal components analysis. Least squares support vector machines and linear discriminant analysis were applied to fit the pairwise and multiclass classifiers, respectively. Significant differences in performance were found when short-TE, long-TE or both spectra combined were used as input. In our dataset, to discriminate meningiomas, the combination of the two TE acquisitions produced optimal performance. To discriminate aggressive tumors from low-grade glial tumours, the use of short-TE acquisition alone was preferable. The classifier development strategy used here lends itself to automated learning and test performance processes, which may be of use for future web-based multicentric classifier development studies.

In vivo measurement of glycine with short echo-time 1H MRS in human brain at 7 T

OBJECT

To determine whether glycine can be measured at 7 T in human brain with (1)H magnetic resonance spectroscopy (MRS).

MATERIALS AND METHODS

The glycine singlet is overlapped by the larger signal of myo-inositol. Density matrix simulations were performed to determine the TE at which the myo-inositol signal was reduced the most, following a single spin-echo excitation. (1)H MRS was performed on an actively shielded 7 T scanner, in five healthy volunteers.

RESULTS

At the TE of 30 ms, the myo-inositol signal intensity was substantially reduced. Quantification using LCModel yielded a glycine-to-creatine ratio of 0.14 +/- 0.01, with a Cramér-Rao lower bound (CRLB) of 7 +/- 1%. Furthermore, quantification of metabolites other than glycine was possible as well, with a CRLB mostly below 10%.

CONCLUSION

It is possible to detect glycine at 7 T in human brain, at the short TE of 30 ms with a single spin-echo excitation scheme.

Proton magnetic resonance spectroscopy in pituitary macroadenomas: preliminary results

OBJECT

The aim of this study was to correlate proton MR (1H-MR) spectroscopy data with histopathological and surgical findings of proliferation and hemorrhage in pituitary macroadenomas.

METHODS

Quantitative 1H-MR spectroscopy was performed on a 1.5-T unit in 37 patients with pituitary macroadenomas. A point-resolved spectroscopy sequence (TR 2000 msec, TE 135 msec) with 128 averages and chemical shift selective pulses for water suppression was used. Voxel dimensions were adapted to ensure that the volume of interest was fully located within the lesion and to obtain optimal homogeneity of the magnetic field. In addition, water-unsuppressed spectra (16 averages) were acquired from the same volume of interest for eddy current correction, absolute quantification of metabolite signals, and determination of full width at half maximum of the unsuppressed water peak (FWHM water). Metabolite concentrations of choline-containing compounds (Cho) were computed using the LCModel program and correlated with MIB-1 as a proliferative cell index from a tissue specimen.

RESULTS

In 16 patients harboring macroadenomas without hemorrhage, there was a strong positive linear correlation between metabolite concentrations of Cho and the MIB-1 proliferative cell index (R = 0.819, p < 0.001). The metabolite concentrations of Cho ranged from 1.8 to 5.2 mM, and the FWHM water was 4.4-11.7 Hz. Eleven patients had a hemorrhagic adenoma and showed no assignable metabolite concentration of Cho, and the FWHM water was 13.4-24.4 Hz. In 10 patients the size of the lesion was too small (< 20 mm in 2 directions) for the acquisition of MR spectroscopy data.

CONCLUSIONS

Quantitative 1H-MR spectroscopy provided important information on the proliferative potential and hemorrhaging of pituitary macroadenomas. These data may be useful for noninvasive structural monitoring of pituitary macroadenomas. Differences in the FWHM water could be explained by iron ions of hemosiderin, which lead to worsened homogeneity of the magnetic field.

[Multivoxel spectroscopy with short echo time: choline/N-acetyl-aspartate ratio and the grading of cerebral astrocytomas]

The choline/N-acetyl-aspartate (Cho/NAA) ratio, obtained by the multivoxel spectroscopy with short echo time (TE), was evaluated, in the histological grading of the brain astrocytomas (grades I, II and III-IV) in comparison with the normal cerebral parenchyma. A significant increase (p<0.05) in the average ratios of Cho/NAA was observed in the three astrocytoma groups studied in relation to normal tissue, having a tendency to increase with the increase in grading, without any statistic significance, which corresponded to: 0.53+/-0.24 in the control group, 1.19+/-0.49 in grade I, 1.58+/-0.65 in grade II and 5.13+/-8.12 in the high grade group (grades III-IV), with variation in the values encountered. There was an increase in the Cho/NAA ratio in 4/5 (80%) in grade I, 5/6 (83%) in grade II and 10/20 (50%) in grades III and IV. We conclude that multivoxel spectroscopy with short TE can be used in discriminating between normal parenchyma and neoplasm tissue. However, not all neoplasm tissue studied presented an increase in Cho/NAA, especially in the group with higher grade of malignancy.

Myo-inositol: a marker of reactive astrogliosis in glial tumors?

In a prospective study, two-dimensional (1)H-MRS with TE of 30 ms was performed before surgery in 56 patients with glial brain tumors. Concentrations of myo-inositol (MI), trimethylamine (TMA) and creatine/phosphocreatine (tCr) were evaluated for the whole tumor and scaled to the normal-appearing contralateral brain tissue. To assign changes in MI to specific tissue pathology, the normalized peak and mean concentrations of MI were correlated with TMA and tCr concentrations. TMA is accepted as a marker of proliferating tumor tissue, and tCr might be a marker of reactive astrogliosis. The mean and peak concentrations of MI and tCr correlated positively (r = 0.7), but not the concentrations of MI and TMA. The absolute concentration of MI was significantly increased in all tumor tissues (5.55 +/- 2.92 mM; mean +/- SD) compared with the normal-appearing white matter (4.33 +/- 1.22 mM, p = 0.005), with the highest concentrations for gliomatoses (n = 10) and grade II oligoastrocytomas (n = 3). Significant differences (P = 0.004) between low- and high-grade astrocytomas were found for TMA (1.67 +/- 0.32 mM and 2.65 +/- 0.86 mM, respectively), but not for MI (5.92 +/- 1.98 mM and 5.49 +/- 3.27 mM, respectively). As increased MI and tCr concentrations were found in gliomatosis and other cerebral diseases associated with marked astrogliosis, this process may also be responsible for the observed changes in MI in other glial tumors.

Ex-vivo NMR of unprocessed tissue in water: a simplified procedure for studying intracranial neoplasms

Ex-vivo and in-vitro nuclear magnetic resonance (NMR) spectroscopy techniques have been used for studying chemical metabolites in surgically resected specimens of human neoplasms, and may provide complementary information to in-vivo whole-body magnetic-resonance spectroscopy (MRS). We describe an ex-vivo NMR in water method for measurement of water-soluble metabolites in unprocessed normal rat brain tissue and human intracranial neoplasms. The NMR spectra obtained using the method described here were comparable to those obtained using high-resolution magic-angle spinning (HRMAS) NMR methods, with good correlation in metabolite concentrations relative to creatine (r2 = 0.7635). Improved spectral resolution and baseline were noted compared to HRMAS, but macromolecule resonances were not detected. Ex-vivo NMR of unprocessed tissue in water is rapid and technically simple to perform, and has the potential to be used for direct assessment of intracranial neoplasms.

Automated MR spectroscopy of intra- and extraventricular neurocytomas

PURPOSE

We evaluated the automated magnetic resonance spectroscopic (MRS) characteristics of intra- and extraventricular neurocytomas.

MATERIALS AND METHODS

One extra- and 4 intraventricular neurocytomas were studied. Automated single-voxel proton MRS was performed with a 1.5 T MR scanner. The results of 6 total automated MR spectra were analyzed for each tumor.

RESULTS

Lactate resonance was detected as a doublet in 3 MR spectra of 2 intraventricular neurocytomas. A peak corresponding to N-acetylaspartate (NAA) was small in 5 MR spectra of 4 intraventricular neurocytomas. Creatine (Cr) resonance was detected in all 6 MR spectra. Prominent choline (Cho) resonance was found in all 6 MR spectra. The myoinositol (MI) and/or glycine (Gly) peaks were large in 3 MR spectra of 2 intraventricular neurocytomas.

CONCLUSION

The presence of the NAA signal and high MI and/or Gly signals may be characteristic features of intraventricular neurocytomas. A combination of prominent Cho resonance and detectable Cr resonance is a common feature of both intra- and extraventricular neurocytomas.

Metabolic profiling of human brain metastases using in vivo proton MR spectroscopy at 3T

Background

Metastases to the central nervous system from different primary cancers are an oncologic challenge as the overall prognosis for these patients is generally poor. The incidence of brain metastases varies with type of primary cancer and is probably increasing due to improved therapies of extracranial metastases prolonging patient's overall survival and thereby time for brain metastases to develop. In addition, the greater access to improved neuroimaging techniques can provide earlier diagnosis. The aim of this study was to investigate the feasibility of using proton magnetic resonance spectroscopy (MRS) and multivariate analyses to characterize brain metastases originating from different primary cancers, to assess changes in spectra during radiation treatment and to correlate the spectra to clinical outcome after treatment.

Methods

Patients (n = 26) with brain metastases were examined using single voxel MRS at a 3T clinical MR system. Five patients were excluded due to poor spectral quality. The spectra were obtained before start (n = 21 patients), immediately after (n = 6 patients) and two months after end of treatment (n = 4 patients). Principal component analysis (PCA) and partial least square regression analysis (PLS) were applied in order to identify clustering of spectra due to origin of metastases and to relate clinical outcome (survival) of the patients to spectral data from the first MR examination.

Results

The PCA results indicated that brain metastases from primary lung and breast cancer were separated into two clusters, while the metastases from malignant melanomas showed no uniformity. The PLS analysis showed a significant correlation between MR spectral data and survival five months after MRS before start of treatment.

Conclusion

MRS determined metabolic profiles analysed by PCA and PLS might give valuable clinical information when planning and evaluating the treatment of brain metastases, and also when deciding to terminate further therapies.

SURGERY OF INTRINSIC CEREBRAL TUMORS

TUMORS AND OTHER structural lesions located with and adjacent to the cerebral cortex present certain challenges in terms of the overall management and design of surgical strategies. This comprehensive analysis attempts to define the current understanding of cerebral localization and function and includes the latest advances in functional imaging, as well as surgical technique, including localization of tumors and neurophysiological mapping to maximize extent of resection while minimizing morbidity. Finally, it remains to be seen whether or not stimulation mapping will be the most useful way to identify function within the cortex in the future. Another potential paradigm would be to actually record baseline oscillatory rhythms within the cortex and, following presentation of a given task, determine if those rhythms are disturbed enough to identify eloquent cortex as a means of functional localization. This would be a paradigm shift away from stimulation mapping, which currently deactivates the cortex, as opposed to identifying an activation function which identifies functional cortex.

Central neurocytoma: typical magnetic resonance spectroscopy findings and atypical ventricular dissemination

PURPOSE

Central neurocytomas (CNCs) are rare neuronal tumors that have a favorable prognosis and lower rate of recurrence compared with other intraventricular neoplasms. Although it may be difficult to distinguish CNC on conventional neuroimaging, typical MR spectroscopy (MRS) features have been reported. We describe the MRI and MRS features of CNC.

MATERIALS AND METHODS

Eight patients with CNC were reviewed. Three patients underwent presurgical in vivo single-voxel MRS at short echo time (TE, 35 ms) and multi-voxel MR spectroscopic imaging at long TE (144 ms). The surgically resected tumor specimen of one of these patients was also studied ex vivo using high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance.

RESULTS

All eight tumors were located in the lateral ventricles. In six patients, CNC extended into the third ventricle, and in two patients the tumor showed further contiguous intraventricular dissemination into the fourth ventricle. In all three patients who underwent MRS, a characteristic metabolite peak was detected at 3.55 parts per million (ppm) at both long and short TE. HRMAS confirmed the presence of elevated glycine (Gly) at 3.55 ppm, without increase in the concentration of myo-inositol found at the same chemical shift. Elevated choline (at 3.2 ppm) was also seen in all three patients.

CONCLUSION

On MRS, CNCs have a typical appearance with a metabolite peak at 3.55 ppm due to increased Gly, and this feature may be helpful in presurgical diagnosis. Although they are rare benign intraventricular tumors, in atypical cases, CNCs can show extensive intraventricular dissemination into the fourth ventricle.

MR spectroscopy in patients with intracranial meningiomas

With magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), we tried to get more pre-operative information in patients with suspicious meningioma concerning the histologic diagnosis especially regarding WHO Grades I and II meningiomas. Apart from the known spectra and metabolites such as choline, creatine and N-acetyl-aspartate (NAA), recent publications have shown that lactate is often found in necrotic tumor tissue. Within a 2 year period, 39 patients with an intracranial meningioma were studied with MRS. In 62.5% of histologic atypical meningiomas (WHO Grade II), a lactate peak could be demonstrated in the pre-operative MRS. Interestingly, also patients with multiple meningiomas show different spectra of their tumors.

Diagnostic impact of proton MR-spectroscopy versus image-guided stereotactic biopsy

BACKGROUND

The aim of this study was to compare the diagnostic accuracy of (1)H MR-spectroscopy versus image-guided stereotactic biopsy.

METHOD

A cohort of 83 consecutive patients with a broad spectrum of brain lesions were examined. Prior to stereotactic biopsy, the patients were subjected to (1)H MR-spectroscopy examination. Diagnostic accuracy of (1)H MR-spectroscopy and image guided stereotactic biopsy was determined for the largest diagnostic subgroups. Each diagnostic procedure was tested for concordance in every subgroup.

FINDINGS

The subgroups of patients comprised: low grade glioma, high grade glioma (grades III and IV), lymphoma and metastasis. For the sensitivity of (1)H MR-spectroscopy ranged from 87.7 in high grade glioma to 92.3% in metastasis and for specificity from 93.3% for high grade glioma to 100% in low grade glioma. The highest positive predictive value of 100% was reached in the subgroup of low grade glioma. The highest negative predictive value was reached in lymphoma and metastasis, 100%. The kappa values were highly significant for all comparisons (p<0.001). The co-efficient ranged from 0.68 to 0.84. It was lowest in assessing high grade glioma and highest in lymphoma.

CONCLUSION

Compared with each other (1)H MR-spectroscopy and image-guided stereotactic biopsy showed a moderate to good, statistically highly significant concordance. In patients in whom operation is at an increased risk e.g., due to severe medical illness, (1)H MR-spectroscopy as a noninvasive procedure may be sufficient to assess the diagnosis.

Paediatric PNET: pre-surgical MRI features

AIM

To describe the preoperative magnetic resonance imaging (MRI) characteristics of primitive neuroectodermal tumours (PNETs), in particular the diffusion-weighted imaging (DWI), MR spectroscopy (MRS) features and cerebrospinal fluid (CSF) tumour dissemination.

MATERIAL AND METHODS

Twelve patients with PNETs were reviewed: nine with medulloblastoma and three with supratentorial PNETs (SPNETs). The MRI examination included contrast-enhanced intracranial and spinal MRI, and in some patients, gradient recalled echo, fluid-attenuated inversion recovery (FLAIR), DWI, and MRS.

RESULTS

All PNETs were either hypointense or isointense on T1-weighted images. Ten of the 12 tumours were either isointense or hypointense on T2-weighted images, and 11 were isointense on FLAIR images. Patients with SPNETs had large, vascular and haemorrhagic tumours. On DWI, all PNETs were hyperintense and had restricted apparent diffusion coefficient. MRS (two patients with medulloblastoma and one with a SPNET), showed elevated choline, decreased N-acetyl aspartate, and a small taurine peak in all three patients. Intraspinal tumour dissemination, visible as uniform or nodular enhancement coating the conus medullaris, was detected in six of 12 patients, two of whom also had intracranial dissemination.

CONCLUSION

PNETs have a characteristic imaging appearance on FLAIR, DWI and MRS, which may help in differentiating these highly cellular neoplasms from other tumours. There is CSF tumour dissemination in a high proportion of patients, and spinal imaging is important for disease staging and to formulate treatment protocols.

Very Late Frontal Relapse of Medulloblastoma Mimicking a Meningioma in an Adult: Usefulness of 1H Magnetic Resonance Spectroscopy and Diffusion-perfusion Magnetic Resonance Imaging for Preoperative Diagnosis: Case Report

OBJECTIVE AND IMPORTANCE:

We present a rare case of very long-term medulloblastoma relapse in an adult patient and discuss the pattern of recurrence and metabolic imaging of the tumor.

CLINICAL PRESENTATION:

A 45-year-old man was referred for evaluation of a frontobasal midline tumor 21 years after treatment of a cerebellar medulloblastoma by surgery followed by chemotherapy and craniospinal radiotherapy. Magnetic resonance images were suggestive of a meningioma. Several hypotheses were discussed, such as other radio-induced tumors, sarcomas, high-grade gliomas, or lymphomas (previous chemotherapy) and even recurrence of medulloblastoma. Preoperative exploration included 1H magnetic resonance single-voxel spectroscopy (35 and 135 ms echo time), diffusion imaging, and perfusion magnetic resonance imaging.

INTERVENTION:

On magnetic resonance spectroscopy, N-acetyl-aspartate and an elevated choline/creatine ratio were retrieved, with a huge unidentified peak at 1.27 parts per million (ppm). Myoinositol signal was present at both echo times. On diffusion imaging, the tumor appeared hyperintense, with a low apparent diffusion coefficient value of 0.689. In the perfusion study, the maximal relative cerebral blood volume was 2. Metabolic imaging favored the diagnosis of medulloblastoma over the initially suspected diagnosis of meningioma. The patient underwent complete removal of the tumor that was confirmed to be a metastasis of his primary medulloblastoma. The postoperative course was uneventful, and complementary courses of radiotherapy and chemotherapy were planned.

CONCLUSION:

Late relapse should be considered, even after several decades, on occurrence of a second intracranial tumor in this context. Our observation validates the clinical interest of preoperative metabolic imaging for brain tumors with distinctive pattern.

3-T Proton Magnetic Resonance Spectroscopy of Central Neurocytoma

Central neurocytoma (CNC), first described by Hassoun et al in 1982, is a rare neuronal tumor of the central nervous system, accounting for 0.25% to 0.5% of all central nervous system tumors. To our knowledge, there are only 5 published articles reporting the magnetic resonance spectroscopy (MRS) findings of neurocytomas. The 3-T proton MRS findings of 3 cases with CNC confirmed by immunohistochemical stains are reported here. Increased choline (Cho)/creatine (Cr) ratios with decreased N-acetylaspartate (NAA)/Cr ratios were observed in all 3 cases, but only 1 case had an increased peak at 3.55 ppm known as glycine (Gly). The other case with an increased alanine peak at 1.5 ppm had a poor prognosis. Therefore, we conclude that the presence of a Gly peak may suggest the diagnosis of CNC but that the absence of Gly does not exclude the diagnosis of CNC.

Multimodal metabolic imaging of cerebral gliomas: positron emission tomography with [18F]fluoroethyl-L-tyrosine and magnetic resonance spectroscopy

OBJECT

The purpose of this study was to determine the predictive value of [18F]fluoroethyl-L-tyrosine (FET)-positron emission tomography (PET) and magnetic resonance (MR) spectroscopy for tumor diagnosis in patients with suspected gliomas.

METHODS

Both FET-PET and MR spectroscopy analyses were performed in 50 consecutive patients with newly diagnosed intracerebral lesions supposed to be diffuse gliomas on contrast-enhanced MR imaging. Lesion/brain ratios of FET uptake greater than 1.6 were considered positive, that is, indicative of tumor. Results of MR spectroscopy were considered positive when N-acetylaspartate (NAA) was decreased in conjunction with an absolute increase of choline (Cho) and an NAA/Cho ratio of 0.7 or less. An FET lesion/brain ratio, an NAA/Cho ratio, and signal abnormalities on MR images were compared with histological findings in neuronavigated biopsy specimens. The FET lesion/brain ratio and the NAA/Cho ratio were identified as significant independent predictors for the histological identification of tumor tissue. The accuracy in distinguishing neoplastic from nonneoplastic tissue could be increased from 68% with the use of MR imaging alone to 97% with MR imaging in conjunction with FET-PET and MR spectroscopy. Sensitivity and specificity for tumor detection were 100 and 81% for MR spectroscopy and 88 and 88% for FET-PET, respectively. Results of histological studies did not reveal tumor tissue in any of the lesions that were negative on FET-PET and MR spectroscopy. In contrast, a tumor diagnosis was made in 97% of the lesions that were positive with both methods.

CONCLUSIONS

In patients with intracerebral lesions supposed to be diffuse gliomas on MR imaging, FET-PET and MR spectroscopy analyses markedly improved the diagnostic efficacy of targeted biopsies.

Assessment of malignancy in gliomas by 3T 1H MR spectroscopy

The purpose of this study was to assess clinical 1H MR spectroscopy (MRS) as a noninvasive method for evaluating brain tumor malignancy at 3T high-field system. Using 3T MRI/MRS system, localized water-suppressed single-voxel technique in patients with brain tumor (i.e., gliomas) was employed to evaluate spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cr) and lactate. On the basis of Cr, these peak areas were quantitated as a relative ratio. The variation of metabolite measurements of the designated region in 10 normal volunteers was less than 10%. Normal ranges of NAA/Cr and Cho/Cr ratios were 1.67+/-018 and 1.16+/-0.15, respectively. NAA/Cr ratio of gliomas was significantly lower than that of the normal tissues (P= .005), but Cho/Cr ratio of gliomas was significantly higher (P= .001). Cho/Cr ratio of high-grade gliomas was significantly higher than that of low-grade gliomas. The present study demonstrated that the neuronal degradation or loss was observed in all gliomas. Higher-grade glioma was correlated with higher Cho/Cr ratio, indicating a significant dependence of Cho levels on malignancy of gliomas. Our results suggest that clinical 1H MR spectroscopy could be useful to predict tumor malignancy.

In vivo quantification of the metabolites in normal brain and brain tumors by proton MR spectroscopy using water as an internal standard

Metabolite concentrations in normal adult brains and in gliomas were quantitatively analyzed by in vivo proton magnetic resonance spectroscopy (MRS) using the fully relaxed water signal as an internal standard. Between January 1998 and October 2001, 28 healthy volunteers and 18 patients with gliomas were examined by in vivo proton MRS. Single-voxel spectra were acquired using the point-resolved spectroscopic (PRESS) pulse sequence with a 1.5 T scanner (TR/TE/Ave = 3000 ms/30 ms/64). The calculated concentrations of N-acetyl-aspartate (NAA), creatine (Cre), choline (Cho), and water(H(2)O) in the normal hemispheric white matter were 23.59 +/- 2.62 mM (mean +/- SD), 13.06 +/- 1.8 mM, 4.28 +/- 0.8 mM, and 47280.96 +/- 5414.85 mM, respectively. The metabolite concentrations were not necessarily uniform in different parts of the brain. The concentrations of NAA and Cre decreased in all gliomas (p < 0.001). The NAA/Cho and NAA/H(2)O ratios can distinguish the normal brain from gliomas and low-grade from high-grade astrocytoma (p < 0.001). The concentration of taurine (Tau) in medulloblastomas was 29.64 +/- 5.76 mM. This is the first quantitative analysis of Tau in medulloblastoma in vivo and confirms earlier in vitro findings.

In vivo quantification of the metabolites in normal brain and brain tumors by proton MR spectroscopy using water as an internal standard

Metabolite concentrations in normal adult brains and in gliomas were quantitatively analyzed by in vivo proton magnetic resonance spectroscopy (MRS) using the fully relaxed water signal as an internal standard. Between January 1998 and October 2001, 28 healthy volunteers and 18 patients with gliomas were examined by in vivo proton MRS. Single voxel spectra were acquired using the point-resolved spectroscopic pulse sequence with a 1.5-T scanner (TR/TE/Ave = 3000 ms/30 ms/64). The calculated concentrations of N-acetyl-aspartate (NAA), creatine (Cre), choline (Cho), and water (H2O) in the normal hemispheric white matter were 23.59 +/- 2.62 mM (mean +/- SD), 13.06 +/- 1.8 mM, 4.28 +/- 0.8 mM, and 47280.96 +/- 5414.85 mM, respectively. The metabolite concentrations were not necessarily uniform in different parts of the brain. The concentrations of NAA and Cre decreased in all gliomas (p < 0.001). The NAA/Cho and NAA/H2O ratios can distinguish the normal brain from gliomas, and low-grade astrocytoma from high-grade group (p < 0.001). The concentration of taurine (Tau) in medulloblastomas was 29.64 +/- 5.76 mM. This is the first quantitative analysis of Tau in medulloblastoma in vivo and confirms earlier in vitro findings.

Assignment of the 2.03 ppm resonance in in vivo 1H MRS of human brain tumour cystic fluid: contribution of macromolecules

MRI and MRS are established techniques for the evaluation of intracranial mass lesions and cysts. The 2.03 ppm signal recorded in their (1)H-MRS spectra is often assigned to NAA from outer volume contamination, although it has also been detected in non-infiltrating tumours and large cysts. We have investigated the molecular origin of this resonance in ten samples of cystic fluids from human brain tumours. The NMR detected content of the 2.03 ppm resonance in 136 ms echo time spectra, assuming an N- CH(3) origin, was 3.19 +/- 1.01 mM. Only one third (34 +/- 12%) of the N-acetyl containing compound (NAC) signal could be extracted by perchloric acid (PCA) indicating that most of it originated in a macromolecular PCA-insoluble component. Chemical analysis of the cyst fluids showed that sialic acid bound to macromolecules would account for 64.3% and hexuronic containing compounds for 29.2% of the NMR-detectable ex vivo signal, 93.4% of the signal at TE 136 ms. Lactate content measured by NMR (6.4 +/- 4.4 mM) and the predominance of NAC originating in sialic acid point to a major origin from tumour rather than from plasma for this 2.03 ppm resonance.

Magnetic resonance spectroscopy of head and neck neoplasms

Magnetic resonance spectroscopy (MRS) is a validated noninvasive method for evaluation of possible malignant tumor and lymph nodes of the head and neck. From its roots as a budding research application, it has made the critical transition to a widespread clinical tool. MRS analyzes the tissue at a molecular level and searches for the presence of specific metabolites, which are markers for malignancy. Differentiation of benign from malignant neoplasm, detection of recurrence of malignant tumor and noninvasive treatment monitoring of treated or untreated tumor are some of the important utilities of MRS. One dimensional 1H-MRS is the most popular and promising technique for spectroscopic analysis while P-31 MRA and two-dimensional correlated spectroscopy (2D COSY) have also showed some promise. This article describes the application of magnetic resonance spectroscopy for evaluation of malignant tumors of the neck.

Proton magnetic resonance spectroscopy: clinical applications in patients with brain lesions

CONTEXT

Proton spectroscopy has been recognized as a safe and noninvasive diagnostic method that, coupled with magnetic resonance imaging techniques, allows for the correlation of anatomical and physiological changes in the metabolic and biochemical processes occurring within previously-determined volumes in the brain. There are two methods of proton magnetic resonance spectroscopy: single voxel and chemical shift imaging.

OBJECTIVE

The present work focused on the clinical applications of proton magnetic resonance spectroscopy in patients with brain lesions.

CONCLUSIONS

In vivo proton spectroscopy allows the detection of certain metabolites in brain tissue, such as N-acetyl aspartate, creatine, choline, myoinositol, amino acids and lipids, among others. N-acetyl aspartate is a neuronal marker and, as such, its concentration will decrease in the presence of aggression to the brain. Choline increase is the main indicator of neoplastic diseases. Myoinositol is raised in patients with Alzheimer's disease. Amino acids are encountered in brain abscesses. The presence of lipids is related to necrotic processes.