Phospholipid and energy metabolism of cancer cells monitored by 31P magnetic resonance spectroscopy: possible clinical significance

Phosphorous Magnetic Resonance Spectroscopy and Molecular Markers in IDH1 Wild Type Glioblastoma

Simple Summary

Gliobastoma is one of the deadliest tumors overall, yet the most common malignant brain tumor. The new World Health Organization Classification of Brain Tumors brought changes in how we look at this type of malignancy. Now we know that glioblastoma is rather a spectrum of similar tumors, but with some distinct characteristics that include molecular footprint, response to therapy and with that overall survival, among others. We hypothesised that by employing phosphorous magnetic resonance we will be able to show differences in cellular energy metabolism in these various subtypes of glioblastoma. For example, we found indices of faster cell reproduction and tumor growth in MGMT-methylated and EGFR-amplified tumors. These tumors also could have reduced energetic state or tissue oxygenation due to the increased necrosis. Tumors with EGFR-amplification could have increased apoptotic activity regardless of their MGMT status. Our study indicated various differences in energetic metabolism in tumors with different molecular characteristics, which could potentially be important in future therapeutic strategies.

Abstract

The World Health Organisation’s (WHO) classification of brain tumors requires consideration of both histological appearance and molecular characteristics. Possible differences in brain energy metabolism could be important in designing future therapeutic strategies. Forty-three patients with primary, isocitrate dehydrogenase 1 (IDH1) wild type glioblastomas (GBMs) were included in this study. Pre-operative standard MRI was obtained with additional phosphorous magnetic resonance spectroscopy (31-P-MRS) imaging. Following microsurgical resection of the tumors, biopsy specimens underwent neuropathological diagnostics including standard molecular diagnosis. The spectroscopy results were correlated with epidermal growth factor (EGFR) and O6-Methylguanine-DNA methyltransferase (MGMT) status. EGFR amplified tumors had significantly lower phosphocreatine (PCr) to adenosine triphosphate (ATP)-PCr/ATP and PCr to inorganic phosphate (Pi)-PCr/Pi ratios, and higher Pi/ATP and phosphomonoesters (PME) to phosphodiesters (PDE)-PME/PDE ratio than those without the amplification. Patients with MGMT-methylated tumors had significantly higher cerebral magnesium (Mg) values and PME/PDE ratio, while their PCr/ATP and PCr/Pi ratios were lower than in patients without the methylation. In survival analysis, not-EGFR-amplified, MGMT-methylated GBMs showed the longest survival. This group had lower PCr/Pi ratio when compared to MGMT-methylated, EGFR-amplified group. PCr/Pi ratio was lower also when compared to the MGMT-unmethylated, EGFR not-amplified group, while PCr/ATP ratio was lower than all other examined groups. Differences in energy metabolism in various molecular subtypes of wild-type-GBMs could be important information in future precision medicine approach.

Zero-Field NMR J-Spectroscopy of Organophosphorus Compounds

Organophosphorus compounds are a wide and diverse class of chemicals playing a crucial role in living organisms. This aspect has been often investigated using nuclear magnetic resonance (NMR), which provides information about molecular structure and function. In this paper, we report the results of theoretical and experimental studies on basic organophosphorus compounds using zero-field NMR, where spin dynamics are investigated in the absence of a magnetic field with the dominant heteronuclear J-coupling. We demonstrate that the zero-field NMR enables distinguishing the chemicals owing to their unique electronic environment even though their spin systems have the same alphabetic designation. Such information can be obtained just in a single measurement, while amplitudes and widths of observed low-field NMR resonances enable the study of processes affecting spin dynamics. An excellent agreement between simulations and measurements of the spectra, particularly in the largest frequency J-couplings range ever reported in zero-field NMR, is demonstrated.

Sodium MRI of glioma in animal models at ultrahigh magnetic fields

High magnetic fields expand our capability to use sodium MRI for biomedical applications. The central goal of this review is devoted to the unique features of sodium MRI in tumor animal models, mainly in glioma, performed at 9.4 and 21.1 T. The ability of sodium MRI to monitor tumor response to therapy was evaluated. It is noteworthy that sodium MRI can detect glioma response to chemotherapy earlier than diffusion MRI. Especially attractive is the ability of sodium MRI to predict tumor therapeutic resistance before therapy. The non-invasive prediction of tumor chemo-resistance by sodium MRI presents a potential to individualize strategies for cancer treatment. Specifics of sodium MRI and technical aspects of imaging are also presented.

Energy status and metabolism in intracranial space occupying lesions: a prospective 31p spectroscopic study

AIM

Intracranial space occupying lesions can be infective or tumour. There are various advanced Magnetic resonance imaging techniques like perfusion, diffusion and proton spectroscopy which can differentiate between them. However, (31) Phosphorus spectroscopy studies the energy status and the metabolism pattern of various tissues and can be used potentially to differentiate between them depending on their Metabolism pattern. Thus, we aimed to study energy status of various intracranial lesions and try to differentiate between them including grades of gliomas.

MATERIALS AND METHODS

(31)PMRS was done in 1.5T MRI in 43 patients prior to surgery or through/via stereo-tactic biopsy, of which 25 were men and 18 women with mean age 41.34 y ranging from 7-71 y. Single voxel phosphorus spectroscopy was done from the solid portion of the lesions and data was analysed and post processed.

RESULTS

Study includes Lymphoma (n=6), Grade 1 and 2 glioma (n=5), grade 3 glioma (n=9), grade 4 glioma(n=6), metastases (n=5), tuberculoma (n=7) and pyogenic abscesses (n=5). The integral values of PME, Pi, PDE, γ-ATP, α-ATP, β-ATP with reference to the position of PCr were calculated along with various ratios. Integral values of Pi and PDE were significantly increased in metastases but decreased in gliomas grade 1-2 compared to other pathologic conditions. Mean integral values of LEP (low energy phosphates) and total phosphates were significantly decreased in gliomas grades 1 and 2 and increased in metastases when compared with other pathologic conditions. PCr /Pi was increased in glioma grades 1, 2 and 3 but decreased in metastases; the significance was observed only in gliomas grade 3 and metastases. Metabolic ratios of PDE/β ATP and Pi/βATP were decreased in glioma grades 1 and 2 and increased in metastases with statistical significance.

CONCLUSION

(31)PMRS may help in differentiating primary from secondary lesions and assess grades of gliomas.

Application of 31P MR spectroscopy to the brain tumors

Objective

To evaluate the clinical feasibility and obtain useful parameters of ³¹P magnetic resonance spectroscopy (MRS) study for making the differential diagnosis of brain tumors.

Materials and Methods

Twenty-eight patients with brain tumorous lesions (22 cases of brain tumor and 6 cases of abscess) and 11 normal volunteers were included. The patients were classified into the astrocytoma group, lymphoma group, metastasis group and the abscess group. We obtained the intracellular pH and the metabolite ratios of phosphomonoesters/phosophodiesters (PME/PDE), PME/inorganic phosphate (Pi), PDE/Pi, PME/adenosine triphosphate (ATP), PDE/ATP, PME/phosphocreatine (PCr), PDE/PCr, PCr/ATP, PCr/Pi, and ATP/Pi, and evaluated the statistical significances.

Results

The brain tumors had a tendency of alkalization (pH = 7.28 ± 0.27, p = 0.090), especially the pH of the lymphoma was significantly increased (pH = 7.45 ± 0.32, p = 0.013). The brain tumor group showed increased PME/PDE ratio compared with that in the normal control group (p = 0.012). The ratios of PME/PDE, PDE/Pi, PME/PCr and PDE/PCr showed statistically significant differences between each brain lesion groups (p < 0.05). The astrocytoma showed an increased PME/PDE and PME/PCr ratio. The ratios of PDE/Pi, PME/PCr, and PDE/PCr in lymphoma group were lower than those in the control group and astrocytoma group. The metastasis group showed an increased PME/PDE ratio, compared with that in the normal control group.

Conclusion

We have obtained the clinically applicable ³¹P MRS, and the pH, PME/PDE, PDE/Pi, PME/PCr, and PDE/PCr ratios are helpful for differentiating among the different types of brain tumors.

A novel application of 1H magnetic resonance spectroscopy: non-invasive identification of spermatogenesis in men with non-obstructive azoospermia

BACKGROUND

About 10% of infertile men have no sperm in their ejaculate due to poor or absent spermatogenesis, also known as non-obstructive azoospermia (NOA). Testis (1)H magnetic resonance spectroscopy ((1)H-MRS) is a non-invasive imaging tool that can potentially identify and localize spermatogenesis in the testis. This study sought to identify metabolic signatures associated with various histological states of spermatogenesis in infertile men.

METHODS

Quantitative high resolution magic angle spinning spectroscopy was performed on snap frozen testicular tissue from 27 men with three classic histological patterns: (i) normal spermatogenesis (men with prior paternity undergoing vasectomy reversal), (ii) maturation arrest (early or late, MA) or (iii) Sertoli-cell only (SCO). Concentrations of 19 tissue metabolites were acquired from each biopsy specimen. One-way ANOVA analysis was used to determine inter-group differences in metabolite concentrations among the three histologic groups.

RESULTS

Phosphocholine (PC) and taurine tissue concentrations were significantly different between normal and SCO tissue. Mean PC concentrations were three times higher in normal testes compared with SCO (5.4 +/- 1.4 versus 1.5 +/- 0.3 mmol/kg; P = 0.01). No differences in metabolite concentrations were observed between normal and MA testes or between SCO and MA testes. Further histologic stratification of MA testes into subsets of those with (early) and without (late) spermatids or mature sperm, identified differences in PC concentrations. A predictive model for sperm presence with (1)H-MRS was developed based upon PC tissue concentrations.

CONCLUSIONS

PC concentrations are significantly higher in testes with spermatogenesis. This suggests that a unique metabolic signature for spermatogenesis is possible using (1)H-MRS which could aid in the non-invasive diagnosis of sperm in men with NOA.

Proton magnetic resonance spectroscopy in prostate tuberculosis

Prostate tuberculosis is an uncommon disease of the prostate, which usually involves the upper urinary tract. In the elderly patients, it may be mistaken for prostate carcinoma, both clinically and by conventional radiology. However, magnetic resonance spectroscopy can provide more information to differentiate prostate tuberculosis from prostate cancer.

Breast cancer imaging: a perspective for the next decade

Breast imaging is largely indicated for detection, diagnosis, and clinical management of breast cancer and for evaluation of the integrity of breast implants. In this work, a prospective view of techniques for breast cancer detection and diagnosis is provided based on an assessment of current trends. The potential role of emerging techniques that are under various stages of research and development is also addressed. It appears that the primary imaging tool for breast cancer screening in the next decade will be high-resolution, high-contrast, anatomical x-ray imaging with or without depth information. MRI and ultrasonography will have an increasingly important adjunctive role for imaging high-risk patients and women with dense breasts. Pilot studies with dedicated breast CT have demonstrated high-resolution three-dimensional imaging capabilities, but several technological barriers must be overcome before clinical adoption. Radionuclide based imaging techniques and x-ray imaging with intravenously injected contrast offer substantial potential as a diagnostic tools and for evaluation of suspicious lesions. Developing optical and electromagnetic imaging techniques hold significant potential for physiologic information and they are likely to be of most value when integrated with or adjunctively used with techniques that provide anatomic information. Experimental studies with breast specimens suggest that phase-sensitive x-ray imaging techniques can provide edge enhancement and contrast improvement but more research is needed to evaluate their potential role in clinical breast imaging. From the technological perspective, in addition to improvements within each modality, there is likely to be a trend towards multi-modality systems that combine anatomic with physiologic information. We are also likely to transition from a standardized screening, where all women undergo the same imaging exam (mammography), to selection of a screening modality or modalities based an individual-risk or other classification.

Three-dimensional magnetic resonance spectroscopic imaging of brain and prostate cancer

Clinical applications of magnetic resonance spectroscopic imaging (MRSI) for the study of brain and prostate cancer have expanded significantly over the past 10 years. Proton MRSI studies of the brain and prostate have demonstrated the feasibility of noninvasively assessing human cancers based on metabolite levels before and after therapy in a clinically reasonable amount of time. MRSI provides a unique biochemical "window" to study cellular metabolism noninvasively. MRSI studies have demonstrated dramatic spectral differences between normal brain tissue (low choline and high N-acetyl aspartate, NAA) and prostate (low choline and high citrate) compared to brain (low NAA, high choline) and prostate (low citrate, high choline) tumors. The presence of edema and necrosis in both the prostate and brain was reflected by a reduction of the intensity of all resonances due to reduced cell density. MRSI was able to discriminate necrosis (absence of all metabolites, except lipids and lactate) from viable normal tissue and cancer following therapy. The results of current MRSI studies also provide evidence that the magnitude of metabolic changes in regions of cancer before therapy as well as the magnitude and time course of metabolic changes after therapy can improve our understanding of cancer aggressiveness and mechanisms of therapeutic response. Clinically, combined MRI/MRSI has already demonstrated the potential for improved diagnosis, staging and treatment planning of brain and prostate cancer. Additionally, studies are under way to determine the accuracy of anatomic and metabolic parameters in providing an objective quantitative basis for assessing disease progression and response to therapy.

1H MRS markers of tumour growth in intrasplenic tumours and liver metastasis induced by injection of HT-29 cells in nude mice spleen

We have characterized, by in vitro magnetic resonance spectroscopy (MRS), the metabolite pattern of perchloric acid (PCA) extracts of intrasplenic tumours and hepatic metastasis, produced by intra-spleen injection of the human colorectal carcinoma cell line HT-29 and its metastatic variant HT-29 MMM into nude mice. Our aim was to gain further understanding of colorectal tumour metabolism as a basis for future in vivo studies of human colon cancer by 1H MRS. Metabolite PCA extract analysis showed a good reproduction of the spectral pattern observed in human primary colon tumours, while they were very different from the spectral pattern of the host tissues (spleen and liver). The main differences between host and tumour tissues involved taurine, phosphocholine (PC), phosphoethanolamine (PE), creatine, glycogen and glucose. Creatine is the most promising marker to follow tumour growth because of its practical absence in the nude mice host tissues. Detection of variable levels of this compound and of taurine in hepatic foci in man, are suggested as possible diagnostic markers. No correlation could be found between spectral pattern differences and the different ability to metastasize of the two HT-29 cell lines used. Furthermore, indirect evidence for a functional link between taurine and myo-inositol in colon tumour cells is presented. In summary, our data suggest that the nude mice model may be a suitable system for the MRS study of the changes taking place in host tissues upon tumour progression.

Quantitative and qualitative characterization of 1H NMR spectra of colon tumors, normal mucosa and their perchloric acid extracts: decreased levels of myo-inositol in tumours can be detected in intact biopsies

Sixteen colonic tumours and 10 normal mucosa biopsies have been examined by 1H NMR spectroscopy at 9.4 T. A complete characterization and quantification of the aliphatic region of PCA extract spectra and the analysis of the two-dimensional COSY spectra of five pairs of intact biopsies (tumor and control mucosa) has been carried out. The analysis of the PCA extracts demonstrated a significant increase in the concentration of the endogenous compounds: lactate, glutamate, aspartate, taurine, spermine, glutathione and glycerophosphoethanolamine, and a significant decrease of myo- and scyllo-inositol, in tumours with respect to mucosae. Among these metabolites, the high myo-inositol and taurine levels and the reciprocal changes found between them in tumours and mucosae make their resonances interesting as possible malignancy markers if they are detectable in vivo. In contrast to the easy observation of taurine in one-dimensional spectra of intact biopsies, the difficulty of observing myo-inositol prompted us to use two-dimensional COSY spectra for the detection and quantification of both these metabolites. In the two-dimensional spectra, the use of a ratio between the cross-peak volumes of both metabolites permits an excellent differentiation between tumours and normal mucosa and suggests its potential to detect malignant changes in the healthy tissue, provided a two-dimensional approach is used.

Characteristic metabolic profiles revealed by 1H NMR spectroscopy for three types of human brain and nervous system tumours

Cell culture techniques, high-resolution in vitro 1H NMR spectroscopy, and chromatographic analyses were used to compare the properties of three types of human brain and nervous system tumours. Cell lines were immunocytochemically characterized at all stages in culture with specific antibodies. Intracellular metabolites present in cell extracts were analysed by 1H NMR spectroscopy and by high performance liquid chromatography (HPLC). The spectra from meningiomas, neuroblastomas, and glioblastomas displayed, in addition to similarities-including the presence of signals from leucine, isoleucine, valine, threonine, lactate, acetate, glutamate, choline-containing compounds and glycine-certain distinguishing metabolic features. Spectra from meningiomas featured relatively high signals from alanine. Intense signals from creatine were present in neuroblastoma spectra, while in spectra from glioblastoma they were not detectable. We found statistically significant differences by 1H NMR spectroscopy in the amounts of alanine, glutamate, creatine, phosphorylcholine and threonine among the types of tumours examined. HPLC determinations confirmed that there were also other metabolites specific to a type of tumour, such as taurine, gamma-aminobutyric acid, and serine. We suggest that these findings have potential relevance for the development of non-invasive diagnosis of tumour lineage by 1H NMR spectroscopy in vivo.

Metabolism of breast cancer cells as revealed by non-invasive magnetic resonance spectroscopy studies

The basis for the use of nuclear magnetic resonance (NMR) spectroscopy as a tool to study the metabolism of breast cancer cells is described. The differences between proton (1H), carbon (13C), and phosphorus (31P) NMR methods is explained, and the techniques of cell extracts, cell suspensions and perfusion methods for cells are detailed. In order to perfuse cells they are preferably trapped in a gel matrix, either in the form of a thread or a bead. The gel must have appropriate properties that enables efficient oxygenation and availability of nutrients and drugs. The metabolic effects of perfusion of breast cancer cells with nutrients, drugs, and hormones are reported, and the clinical relevance of these results and methods are outlined.

Characterization of human prostate cancer, benign prostatic hyperplasia and normal prostate by in vitro 1H and 31P magnetic resonance spectroscopy

In vitro 1H and 31P magnetic resonance spectra were acquired from perchloric acid extracts of human prostate tissue obtained by transurethral resection. This included tissue of patients with benign prostatic hyperplasia and prostatic adenocarcinoma; one tissue sample was obtained from a patient without any sign of BPH or malignancy. Major resonances in the magnetic resonance spectra were assigned to prostate compounds and were quantified. The citrate/lactate, citrate/total choline, phosphocholine/total creatinine, choline/total creatine, alanine/total creatine, phosphoethanolamine/total phosphate, phosphocholine/total phosphate and glycerophosphoethanolamine/total phosphate ratios were statistically different for the prostate cancer samples as compared with the BPH specimens. These observations may contribute to the understanding of in vivo magnetic resonance spectra of the prostate and indicate that magnetic resonance spectroscopy can aid in the diagnosis of prostate malignancy.

Citrate alterations in primary and metastatic human prostatic adenocarcinomas: 1H magnetic resonance spectroscopy and biochemical study

The objectives of this study were to quantitatively verify the low levels of citrate previously observed in primary human prostatic adenocarcinomas and to determine whether citrate was further reduced in metastatic prostatic cancer. This was accomplished by comparison of citrate concentrations of DU 145 xenografts (a poorly differentiated human prostatic adenocarcinoma cell line grown in nude mice) with concentrations in primary human adenocarcinomas. Following in vivo 1H NMR studies of DU 145 xenografts, citrate concentrations of DU 145 xenografts and surgically removed primary prostatic adenocarcinoma tissue were determined by quantitative high resolution 1H NMR and enzymatic assay. The most significant findings of this study were that citrate concentrations in primary human adenocarcinomas (3.74 +/- 0.19 mumol/g wet weight) were significantly lower than those observed for normal and benign hyperplastic (BPH) prostatic tissues. Furthermore there was a further ten-fold reduction of citrate associated with DU 145 xenografts (0.31 +/- 0.028 mumole/g wet weight) compared with primary prostatic cancer. DU 145 xenografts also exhibited higher levels of uridine diphosphosugars and choline containing metabolites relative to primary prostatic adenocarcinomas. These findings support the hypothesis that citrate is low in primary prostatic cancer and further reduced in metastatic disease.

Magnetic resonance spectroscopy in prostate disease: diagnostic possibilities and future developments

Magnetic resonance spectroscopy (MRS) is a relatively new technique for studying membrane and intracellular metabolic events occurring in cancer. A series of transrectal probes were used for performing MRS and subsequently for integrated MRS/magnetic resonance imaging (MRI) of the prostate. Studies using transrectal 31P/1H MRS showed that it can characterize metabolic differences between normal and malignant prostates. Specifically, malignant prostates are characterized by low levels of phosphocreatine and citrate and high levels of phosphomonoesters relative to normal glands. These findings were verified in biochemical studies of prostate biopsies. The images obtained by transrectal coil techniques were superior to images obtained by the conventional body coil technique. In the future, the integration of 1H imaging and multi-volume localization techniques (spectroscopic imaging) will allow the acquisition of metabolic maps of the prostate which may eventually be useful in diagnosis and in management of patients with prostate cancer.

31P spectroscopy of the human prostate gland in vivo using a transrectal probe

Using a transrectal probe, good quality 31P magnetic resonance spectroscopy of the human prostate was performed safely, consistently, and in a reasonable amount of time (average of 60 min). Initial results indicate that transrectal 31P MRS has the ability to characterize the phosphorylated metabolites of normal, hyperplastic, and malignant prostates. This study demonstrated that malignant prostates are characterized by significantly decreased levels of phosphocreatine (PCr) and increased levels of phosphomonoesters (PME) as compared to healthy prostates.

31P nuclear magnetic resonance spectroscopy, histology and cytokinetics of a xenografted hypopharynx carcinoma following treatment with cisplatin: comparison in three sublines with increasing resistance

The changes in the phosphorus metabolism of a xenografted hypopharynx carcinoma (Hyp 1), sensitive to cisplatin (CDDP), were compared to those occurring in two sublines of the tumour, characterised by moderate or high resistance to CDDP (Hyp 1/H and Hyp 1/R) following, i.p. administration of 4, 8 or 12 mg CDDP/kg-1. The investigations were performed by in vivo 31P nuclear magnetic resonance (NMR) spectroscopy. Parallel to the NMR experiments, the cytokinetic and histological alterations in the tumours were studied under the same experimental conditions. No mentionable differences in the levels of the main phosphorus-containing metabolites could be detected between the three tumour lines before treatment. Following application of CDDP, the alterations in the NMR spectra were clearly related to the degree of tumour response. The most sensitive and earliest marker of tumour regression was a decrease in the phosphomonoester/phosphodiester ratio, parallelled by a gradual increase in the phosphocreatine/inorganic phosphorus quotient. In the resistant tumour lines Hyp 1/H and Hyp 1/R non-responding tumours showed alterations in the 31P NMR spectrum which were similar to those observed during uninfluenced tumour growth. Marked changes in the 31P NMR spectrum were always associated with severe cytotoxic lesions following therapy. The results suggest that the changes detected by 31P NMR spectroscopy following chemotherapy with CDDP are response-specific.

Characterization of prostate cancer, benign prostatic hyperplasia and normal prostates using transrectal 31phosphorus magnetic resonance spectroscopy: a preliminary report

We assessed the ability of 31phosphorus (31P) transrectal magnetic resonance spectroscopy to characterize normal human prostates as well as prostates with benign and malignant neoplasms. With a transrectal probe that we devised for surface coil spectroscopy we studied 15 individuals with normal (5), benign hyperplastic (4) and malignant (6) prostates. Digital rectal examination, transrectal ultrasonography and magnetic resonance imaging were used to aid in accurate positioning of the transrectal probe against the region of interest within the prostate. The major findings of the in vivo studies were that normal prostates had phosphocreatine-to-adenosine triphosphate (ATP) ratios of 1.2 +/- 0.2, phosphomonoester-to-beta-ATP ratios of 1.1 +/- 0.1 and phosphomonoester-to-phosphocreatine ratios of 0.9 +/- 0.1. Malignant prostates had phosphocreatine-to-beta-ATP ratios that were lower (0.7 +/- 0.1) than those of normal prostates (p less than 0.02) or prostates with benign hyperplasia (1.1 +/- 0.2, p less than 0.01). Malignant prostates had phosphomonoester-to-beta-ATP ratios (1.8 +/- 0.2) that were higher than that of normal prostates (p less than 0.02). Using the phosphomonoester-to-phosphocreatine ratio, it was possible to differentiate metabolically malignant (2.7 +/- 0.3) from normal prostates (p less than 0.001), with no overlap of individual ratios. The mean phosphomonoester-to-phosphocreatine ratio (1.5 +/- 0.5) of prostates with benign hyperplasia was midway between the normal and malignant ratios, and there was overlap between individual phosphomonoester-to-phosphocreatine ratios of benign prostatic hyperplasia glands with that of normal and malignant glands. To verify the in vivo results, we performed high resolution magnetic resonance spectroscopy on perchloric acid extracts of benign prostatic hyperplasia tissue obtained at operation and on a human prostatic cancer cell line DU145. The extract results confirmed the differences in metabolite ratios observed in vivo. We conclude that transrectal 31P magnetic resonance spectroscopy can characterize metabolic differences between the normal and malignant prostate.

31P localized magnetic resonance spectroscopy of head and neck tumors--preliminary findings

Magnetic resonance imaging (MRI) is a powerful tool for accurate assessment of the anatomic extent of head and neck neoplasms. The development of methods for spatial localization by use of multiply tuned radio frequency coils that permit the measurement of multiple nuclear MR spectra (1H and 31P) from precisely defined volumes of interest has provided a basis for integrating spectroscopy into the clinical MRI examination. This offers a means for noninvasive monitoring of relative concentrations of mobile metabolites within a tumor. With the use of imaging to determine proper coil placement, a test-retest variance of about 17% is seen on MR spectroscopy. Data are presented from MRI/MRS studies for four head and neck lesions: (1) a squamous cell carcinoma of the lip; (2) a juvenile angiofibroma extending into the nasal cavity; (3) a massive chondrosarcoma of the nasal septum; and (4) a cervical nodal metastasis of a squamous cell carcinoma of the pharynx. Spectra are evaluated by comparison of relative concentrations of phosphorus compounds. The concentrations of phosphomonoesters and phosphodiesters are significantly higher in the neoplasms studied than in normal skeletal muscle. The developing role of integrated MRI/MRS to monitor the response of malignant neoplasm to radiation therapy is discussed.

Localized 31P magnetic resonance spectroscopy of large pediatric brain tumors

Fourteen children aged 1 week to 16 years, with a variety of large or superficial brain tumors, underwent localized in vivo 31P magnetic resonance spectroscopy of their tumor. Quantitative spectral analysis was performed by measuring the area under individual peaks using a computer algorithm. In eight patients with histologically benign tumors the spectra were considered to be qualitatively indistinguishable from normal brain. The phosphocreatine/inorganic phosphate ratio (PCr/Pi) averaged 2.0. Five patients had histologically malignant tumors; qualitatively, four of these were considered to have abnormal spectra, showing a decrease in the PCr peak. The PCr/Pi ratio for this group averaged 0.85, which was significantly lower than that seen in the benign tumor group (p less than 0.05). No difference between the two groups was seen in adenosine triphosphate or phosphomonoesters. It is concluded that a specific metabolic "fingerprint" for childhood brain tumors may not exist, but that some malignant tumors show a pattern suggestive of ischemia.

The use of magnetic resonance imaging and spectroscopy in the assessment of patients with head and neck and other superficial human malignancies

The proper demarcation of diseased tissue is important for radiation therapy planning and treatment. The volume to be irradiated is usually identified on radiographs or on x-ray computed tomography (CT) sections. Magnetic resonance (MR)-derived images of the proton T2 relaxation times in small pixel elements, typically 0.5 mm2 or less, provide significantly sharper differentiation between normal and diseased tissue. The T2 values in tissue depend on the tissue composition, histologic condition, and physiologic environment within the tumor. Furthermore, for many tumors the histogram of T2 values has a clear biphasic distribution suggesting that T2 maps may be useful for the identification of necrotic or hypoxic regions within tumors. The distribution of T2 values within the tumor bed shows the general pattern that the T2 values are elevated with a range greater than that seen in normal muscle. Elevated T2 values are not by themselves diagnostic of malignancy; however, they demonstrate the heterogeneity of the microenvironment present within a tumor. The spatial distribution of T2 values is being explored as a method for computer assistance in the delineation of the target volume for treatment planning. In addition, MR P-31 spectroscopic examinations were performed on 30 patients with squamous cell carcinomas of the head and neck. Although hampered by muscle contamination in some P-31 spectra obtained with surface coil profile localization techniques, significant trends can still be appreciated in our data. These trends include the following: (1) the P-31 spectra from malignant tissue have well-resolved spectral lines in the upfield region that correspond to Pi, phosphomonoester (PME), and phosphodiester (PDE) not usually seen in normal muscle; (2) the PDE/B-ATP and PME/B-ATP ratios are greater than unity in all cases; and (3) most of the tumors have higher PME peaks than PDE peaks. The P-31 spectra from patients treated with ionizing radiation changed during and after therapy. Some of the changes could be associated with alteration of the tumor metabolic activity or synthesis and breakdown of lipoproteins. These studies suggest that magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies may be useful for both radiotherapy treatment planning and the noninvasive monitoring of patients both before and during treatment.