Abnormal phosphomonoester signals in 31P MR spectra from patients with hepatic lymphoma. A possible marker of liver infiltration and response to chemotherapy

Hepatic infiltration by lymphoma can be difficult to detect by conventional methods. We have studied 22 patients in vivo 31P magnetic resonance spectroscopy of the liver and compared the results with the clinical staging and assessment of liver involvement by computed tomography (CT), ultrasound (US), and liver function tests (LFTs). We find that the phosphomonoester (PME) to ATP, and the PME to Pi ratios are the best indication of liver involvement as in all the patients with liver involvement apparent on CT or US, these ratios were elevated (greater than 2 s.d. above the control mean). Of the patients with deranged LFTs but normal CT or US, five out of nine showed increased PME/ATP and PME/Pi ratios, and in the patients with normal LFTs and normal CT or US, three out of eight patients had raised PME ratios. Extracts of lymphomatous lymph nodes contain high concentrations of phosphoethanolamine which suggests that this compound is responsible for the increase in the PME peak. Eleven patients were studied again after chemotherapy, and those with initially raised PME/ATP and PME/Pi ratios all showed a decrease in these ratios towards normal. The patients with initially normal ratios showed no changes.     

Tumor dose response to the vascular disrupting agent, 5,6-dimethylxanthenone-4-acetic acid, using in vivo magnetic resonance spectroscopy.

PURPOSE: To use (31)P and (1)H magnetic resonance spectroscopy (MRS) to assess changes in tumor metabolic profile in vivo in response to 5,6-dimethylxanthenone-4-acetic acid (DMXAA) with a view to identifying biomarkers associated with tumor dose response.EXPERIMENTAL DESIGN: In vivo (31)P and (1)H MRS measurements of (a) tumor bioenergetics [beta-nucleoside triphosphate/inorganic phosphate (beta-NTP/Pi)], (b) the membrane-associated phosphodiesters and phosphomonoesters (PDE/PME), (c) choline (mmol/L), and (d) lactate/water ratio were made on murine HT29 colon carcinoma xenografts pretreatment and 6 or 24 hours posttreatment with increasing doses of DMXAA. Following in vivo MRS, the tumors were excised and used for high-resolution (31)P and (1)H MRS of extracts to provide validation of the in vivo MRS data, histologic analysis of necrosis, and high-performance liquid chromatography.RESULTS: Both beta-NTP/Pi and PDE/PME decreased in a dose-dependent manner 6 hours posttreatment with DMXAA, with significant decreases in beta-NTP/Pi with 15 mg/kg (P < 0.001) and 21 mg/kg (P < 0.01). A significant decrease in total choline in vivo was found 24 hours posttreatment with 21 mg/kg DMXAA (P < 0.05); this was associated with a significant reduction in the concentration of the membrane degradation products glycerophosphoethanolamine and glycerophosphocholine measured in tissue extracts (P < 0.05).CONCLUSIONS: The reduction in tumor energetics and membrane turnover is consistent with the vascular-disrupting activity of DMXAA. (31)P MRS revealed tumor response to DMXAA at doses below the maximum tolerated dose for mice. Both (31)P and (1)H MRS provide biomarkers of tumor response to DMXAA that could be used in clinical trials.     

Phosphorus metabolism during growth of lymphoma in mouse liver: a comparison of 31P magnetic resonance spectroscopy in vivo and in vitro.

Large phosphomonoester (PME) signals are detected in the phosphorus magnetic resonance spectra (31P MRS) of many neoplastic and rapidly dividing tissues. In addition, alterations in phosphodiester (PDE) signals are sometimes seen. The present study of a murine lymphoma growing in liver showed a positive correlation between the hepatic PME/PDE ratio measured in vivo by 31P MRS at 4.7 T and the degree of lymphomatous infiltration in the liver, quantified by histology. High-resolution 31P MRS of liver extracts at 9.7 T showed that the PME peak consists largely of phosphoethanolamine (PE) and to a lesser extent of phosphocholine (PC). The concentration of both PE and PC increased positively with lymphomatous infiltration of the liver. In vivo, the PDE peak contains signals from phospholipids (mostly phosphatidylethanolamine and phosphatidylcholine) and the phospholipid breakdown products glycerophosphoethanolamine (GPE) and glycerophosphocholine (GPC). Low levels of GPE and GPC were detected in the aqueous extracts of the control and infiltrated livers; their concentrations remained unchanged as the infiltration increased. The total concentration of phospholipids measured by 31P MRS of organic extracts decreased about 3-fold as the infiltration increased to 70%. Thus, our data showed that the increased PME/PDE ratio in vivo is due to both an increase in the PME metabolites and a decrease in the PDE metabolites. We propose that this ratio can be used as a non-invasive measure of the degree of lymphomatous infiltration in vivo.     

Relation between pO2, 31P magnetic resonance spectroscopy parameters and treatment outcome in patients with high-grade soft tissue sarcomas treated with thermoradiotherapy

PURPOSE: In a prior study, the combination of (31)P magnetic resonance spectroscopy (MRS)-based intracellular pH (pHi) and T2 relaxation time was highly predictive of the pathologic complete response (pCR) rate in a small series of patients with soft tissue sarcomas (STSs) treated with thermoradiotherapy. Changes in the magnetic resonance metabolite ratios and pO(2) were related to the pCR rate. Hypoxia also correlated with a greater likelihood for the development of metastases. Because of the limited number of patients in the prior series, we initiated this study to determine whether the prior observations were repeatable and whether (31)P MRS lipid-related resonances were related to a propensity for metastasis. METHODS AND MATERIALS: Patients with high-grade STSs were enrolled in an institutional review board-approved Phase II thermoradiotherapy trial. All tumors received daily external beam radiotherapy (1.8-2.0 Gy, five times weekly) to a total dose of 30-50 Gy. Hyperthermia followed radiotherapy by <1 h and was given two times weekly. Tumors were resected 4-6 weeks after radiotherapy completion. The MRS/MRI parameters included (31)P metabolite ratios, pHi, and T2 relaxation time. The median pO(2) and hypoxic fraction were determined using pO(2) histography. Comparisons between experimental endpoints and the pCR rate and metastasis-free and overall survival were made. RESULTS: Of 35 patients, 21 and 28 had reportable pretreatment MRS/MRI and pO(2) data, respectively. The cutpoints for a previously tested receiver operating curve for a pCR were T2 = 100 and pHi = 7.3. In the current series, few tumors fell below the cutpoints so validation was not possible. The phosphodiester (PDE)/inorganic phosphate (Pi) ratio and hypoxic fraction correlated inversely with the pCR rate in the current series (Spearman correlation coefficient -0.51, p = 0.017; odds ratio of percentage of necrosis > or =95% = 0.01 for a 1% increase in the hypoxic fraction; Wald p = 0.036). The pretreatment phosphomonoester (PME)/Pi ratio also correlated inversely with the pCR rate (odds ratio of percentage of necrosis > or =95% = 0.06 for pretreatment PME/Pi ratio >0.8 vs. < or =0.8, Wald p = 0.023). The pretreatment PME/PDE ratio correlated strongly with metastasis-free survival and overall survival (p = 0.012 and hazard ratio = 5.8, and p = 0.038 and hazard ratio = 6.75, respectively). CONCLUSION: The dual parameter model containing pHi and T2 to predict the pCR in STSs treated with thermoradiotherapy was not verified. However, other parameters were statistically significant, including the PDE/Pi ratio and hypoxic fraction. These relationships may have interfered with our ability to obtain the pCR rate predicted by thermal doses achieved in these patients. The relationship between the PME/PDE ratio and metastasis-free and overall survival was provocative, but requires additional study to verify its predictive capability. Currently, 50% of all STS patients with high-grade tumors develop distant metastasis even when excellent local control is achieved. Parameters that could help select for patients who need adjuvant chemotherapy could have significant clinical benefit.     

In vivo 31P-NMR spectroscopy of murine tumours before and after localized hyperthermia

In vivo 31P-NMR spectroscopy was used to monitor the energy metabolism, apparent intracellular pH (pHNMR), and phospholipid turnover in subcutaneous fibrosarcomas (FSall) and mammary carcinomas (MCaIV) treated with hyperthermia (HT). Treatment consisted of elevation of tumour temperature to 43.5 degrees C for 15, 30 or 60 min (FSall) and 30 min (MCaIV). Experiments were performed on conscious mice with biologically relevant tumour sizes. Using water bath immersion, this study focused on acute heat-induced metabolic changes (up to 7 h post-HT). 31P-NMR spectra of both murine tumours were characterized by relatively high pretreatment levels of PME, Pi and NTP, and lower levels of PDE, PCr and DPDE. Following hyperthermia, NTP and PCr levels, as well as pHNMR, decreased in both tumour lines. This drop was accompanied by a prompt and dramatic increase in Pi. After heating for 15 min, the limited spectral changes observed for the high-energy phosphates and the marginal decline in pHNMR were nullified within 7 h, whereas Pi remained significantly elevated. With the exception of PME/NTP and PME/PDE, all relevant metabolic ratios (PCr/Pi, NTP/Pi, PME/Pi) decreased after heating and did not resolve thereafter. Upon longer heat exposure times the high-energy phosphates, pHNMR, NTP/Pi, PCr/Pi, and PME/Pi all decreased in a dose-dependent manner and remained at the respective lower levels. The PME/PDE ratio was increased after 43.5 degrees C/15 min whereas at longer heating times this ratio did not change. At comparable heat doses MCaIV tumours seem to exhibit changes similar to FSall tumours.     

Phosphomonoester is associated with proliferation in human breast cancer: a 31P MRS study.

Phospholipid metabolism of human breast cancer was studied by 31P magnetic resonance spectroscopy (MRS). In vivo localised 31P MR spectra were obtained from the tumour alone using phase modulated rotating frame imaging. For 31 tumours, median (range) phosphomonoester (PME) to ATP ratio was 1.48 (0.57-3.78) and phosphodiester (PDE) to ATP ratio was 1.65 (0.44-3.89). DNA index and S phase fraction (SPF) were measured by flow cytometry of paraffin embedded tissue. Twelve (39%) tumours were diploid and 19 aneuploid. Median (range) SPF for 29 assessable tumours was 5.3% (0.6-28%), with significantly greater median SPF for aneuploid tumours (9.3%) than diploid (3.8%, P = 0.007). There was a significant association between PME/ATP and SPF (P = 0.03) due to a significant correlation for aneuploid tumours (P = 0.01). High resolution 31P MRS of extracts from 18 tumours (including seven studied in vivo) demonstrated that the PME peak consists predominantly of phosphoethanolamine (PE) with a smaller contribution from phosphocholine (PC) (median (range) PE/PC: 3.02 (1.13-5.09)). Changes in PME/ATP were observed for two tumours where tamoxifen stablized disease and may be consistent with the cytostatic effects of this drug.     

Dietary fat modulation of murine mammary tumor metabolism studied by in vivo 31P-nuclear magnetic resonance spectroscopy

The effect of dietary fat concentration and saturation on high energy phosphate metabolites and phospholipid turnover in transplanted line 168 murine mammary tumors was studied using surface coil 31P-nuclear magnetic resonance spectroscopy. Female BALB/c mice were fed one of five diets each containing at least the minimum of essential fatty acids (EFA). Four diets contained additional safflower or palm oil for a total fat concentration of 5 or 20% by weight. The growth rate of tumors from mice fed the high safflower oil diet was significantly greater than the growth rate of tumors for mice fed all other diets including the one which contained the minimal EFA. 31P-nuclear magnetic resonance-observable phosphate metabolite ratios. ATP/Pi, ATP/phosphomonoester (ATP/PME), and PME/Pi, and tumor pH of line 168 tumors decreased with increasing tumor volume, indicating a shift from active to inactive tumor metabolism. The rates of those decreases with progressive tumor growth differed significantly among tumors of mice fed the different diets. Decreases in ATP/Pi, ATP/PME, and pH were the most rapid in the tumors of mice fed the high safflower oil diet and significantly faster than tumors of mice fed the diet containing minimum EFA. In addition, the decrease in the PME/Pi ratio of tumors was significantly greater in mice fed the high fat (high palm oil and high safflower oil) diets than mice fed the diet containing the minimum of EFA. The rate of decline of ATP/Pi and ATP/PME with progressive tumor growth was directly correlated with levels of linoleic acid as well as total unsaturated fat. High levels of a polyunsaturated fat had a significant effect on mammary tumor metabolism particularly during early stages of tumor growth. Differences in high energy phosphate metabolite dynamics relative to dietary fat were present in tumors of equal volume. Thus, dietary fat influences on mammary tumorigenesis may be related to high energy phosphate metabolites.     

31P-nuclear magnetic resonance spectroscopy in vivo of six human melanoma xenograft lines: tumour bioenergetic status and blood supply.

Six human melanoma xenograft lines grown s.c. in BALB/c-nu/nu mice were subjected to 31P-nuclear magnetic resonance (31P-NMR) spectroscopy in vivo. The following resonances were detected: phosphomonoesters (PME), inorganic phosphate (Pi), phosphodiesters (PDE), phosphocreatine (PCr) and nucleoside triphosphate gamma, alpha and beta (NTP gamma, alpha and beta). The main purpose of the work was to search for possible relationships between 31P-NMR resonance ratios and tumour pH on the one hand and blood supply per viable tumour cell on the other. The latter parameter was measured by using the 86Rb uptake method. Tumour bioenergetic status [the (PCr + NTP beta)/Pi resonance ratio], tumour pH and blood supply per viable tumour cell decreased with increasing tumour volume for five of the six xenograft lines. The decrease in tumour bioenergetic status was due to a decrease in the (PCr + NTP beta)/total resonance ratio as well as an increase in the Pi/total resonance ratio. The decrease in the (PCr + NTP beta)/total resonance ratio was mainly a consequence of a decrease in the PCr/total resonance ratio for two lines and mainly a consequence of a decrease in the NTP beta/total resonance ratio for three lines. The magnitude of the decrease in the (PCr + NTP beta)/total resonance ratio and the magnitude of the decrease in tumour pH were correlated to the magnitude of the decrease in blood supply per viable tumour cell. Tumour pH decreased with decreasing tumour bioenergetic status, and the magnitude of this decrease was larger for the tumour lines showing a high than for those showing a low blood supply per viable tumour cell. No correlations across the tumour lines were found between tumour pH and tumour bioenergetic status or any other resonance ratio on the one hand and blood supply per viable tumour cell on the other. The differences in the 31P-NMR spectrum between the tumour lines were probably caused by differences in the intrinsic biochemical properties of the tumour cells rather than by the differences in blood supply per viable tumour cell. Biochemical properties of particular importance included rate of respiration, glycolytic capacity and tolerance to hypoxic stress. On the other hand, tumour bioenergetic status and tumour pH were correlated to blood supply per viable tumour cell within individual tumour lines. These observations suggest that 31P-NMR spectroscopy may be developed to be a clinically useful method for monitoring tumour blood supply and parameters related to tumour blood supply during and after physiological intervention and tumour treatment. However, clinically useful parameters for prediction of tumour treatment resistance caused by insufficient blood supply can probably not be derived from a single 31P-NMR spectrum since correlations across tumour lines were not detected; additional information is needed.     

Early effects of radiotherapy in small cell lung cancer xenografts monitored by 31P magnetic resonance spectroscopy and biochemical analysis

31P magnetic resonance spectroscopy (31P MRS) and biochemical analysis of extracts were applied to study the metabolic response to X-irradiation of small cell lung cancer in nude mice. Two small cell lung cancer xenografts, CPH SCCL 54A and 54B, with different radiosensitivity, although derived from the same patient, were studied. A total of 126 individual tumors were examined. Following 5.0-Gy irradiation, a reversible increase in the ATP/Pi ratio, reaching twice the pretreatment level within 2 wk, was observed with 31P MRS, while 20 Gy induced a reversible decrease in the ATP/Pi ratio. The t1/2 of this decline was 2 to 3 h for 54A and about 6 h for the less radiosensitive 54B. The 31P MRS data were compared with biochemical analysis of tumors freeze-clamped and extracted at similar intervals after 20 Gy. It appeared that an acute reversible increase in Pi concentration was the major cause of the ATP/Pi decrease induced by 20 Gy. A linear correlation between ATP/Pi estimated by 31P MRS and by analytical biochemistry was found. The ATP/Pi ratio may be valuable for early assessment of radiosensitivity of small cell lung cancer tumors.     

Correlations between in vivo 31P NMR spectroscopy measurements, tumor size, hypoxic fraction and cell survival after radiotherapy

Phosphorus metabolite levels were measured non-invasively using 31P magnetic resonance spectroscopy (MRS) in SCCVII/SF tumors, subcutaneously transplanted into the legs of unanesthetized C3Hf/Sed mice. Shortly after MRS measurements, tumors were irradiated with a single dose of 20 Gy, and cell survival and radiobiologic hypoxic fraction were determined with an in vitro cloning assay. Significant correlations were found between tumor size and surviving fraction, hypoxic fraction, pH, and phosphorus metabolite ratios. With increase of tumor size, surviving fraction and hypoxic fraction both increased, the ratios of inorganic phosphate and phosphomonoesters to nucleoside triphosphates (Pi/NTP and PME/NTP, respectively) and inorganic phosphate to phosphocreatine (Pi/PCr) increased and pH decreased. However, considerable heterogeneity of MRS spectral parameters, even in tumors of similar size, precluded accurate prediction of hypoxic fraction and cell survival after radiotherapy.     

31P NMR spectroscopy measurements of human ovarian carcinoma xenografts: relationship to tumour volume, growth rate, necrotic fraction and differentiation status

31P NMR spectroscopy was used to study lipid and energy metabolism as well as tumour pH in three human ovarian carcinoma xenograft lines with widely differing growth rate, necrotic fraction and differentiation status. Two of the lines showed decreasing PCr (phosphocreatine) and NTP beta (nucleoside triphosphates beta) resonances and an increasing Pi (inorganic phosphate) resonance with increasing tumour volume range 100-4000 mm (3). This decrease in bioenergetic status was accompanied by a decrease in tumour pH from 7.15 to about 6.95. The volume-dependence of these spectral parameters probably reflected increased nutritional deprivation and development of hypoxia and necrosis during tumour growth. The phosphomonoesters (PME) and phosphodiesters (PDE) resonances did not change significantly with tumour volume. The third xenograft line did not show changes in the intensity of any of the resonances during tumour growth, in agreement with the observation that necrotic fraction and tumour pH (about 7.0) remained constant over the entire volume range. The spectral parameters differed significantly among the xenograft lines at given tumour volumes, but no correlations with volume-doubling time, necrotic fraction or differentiation status were found. The xenograft lines showed less extensive volume-dependence of the spectral parameters than did the KHT and RIF-1 murine tumour lines under identical experimental conditions.     

Phosphorus-31 metabolism of post-menopausal breast cancer studied in vivo by magnetic resonance spectroscopy.

We have studied the metabolism of 31P-containing metabolites of post-menopausal breast cancers in vivo using magnetic resonance spectroscopy (MRS) and a 5.5 cm surface coil. Spectra were acquired from 23 diameter. The spectra of the 19 previously untreated tumours had significantly higher phosphomonoester (PME) 31P relative peak areas than the normal breasts of eight post-menopausal women (11.7% and 7.7% respectively, P = 0.002). Although an increased PME relative peak area was characteristic of malignancy, PME relative peak area is similarly raised in lactating breast and, therefore, not a specific feature of cancer. An apparently lower nucleotide triphosphate (NTP) relative peak area in tumours than healthy postmenopausal breast was secondary to the differences in PME relative peak area; contamination by signal from chest wall muscle probably accounts for the ostensibly higher phosphocreatine (PCr) relative peak area of the tumours. Spectroscopy was repeated following chemotherapy in six women. An increase in PCr relative peak area was seen in all five patients who responded, but again this may represent increased contamination secondary to changes in tumour size. A fall in PME relative peak area was noted in four responders, but also one non-responder, so this finding may not be sufficiently specific to be of use clinically. Further studies are need to elucidate fully the role of MRS in breast cancer.     

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.     

Altered phosphorylation status, phospholipid metabolism and gluconeogenesis in the host liver of rats with prostate cancer: a 31P magnetic resonance spectroscopy study.

31P magnetic resonance spectroscopy (MRS) in vivo and in vitro was used to study modulation of host liver (HL) metabolism in rats bearing the MAT-LyLu variant of the Dunning prostate tumour. Animals were inoculated either with 10(6) or 10(7) MAT-LyLu cells, or with saline to serve as controls. Carcass weight in tumour-bearing (TB) animals decreased despite similar food and water intake in both groups. Absence of metastatic tumour cells from HL of all TB animals was confirmed by histological examination. Twenty-one days after inoculation, 31P MRS showed a 2.5-fold increase in [Pi]/[ATP] ratios in HL in vivo (P < 0.001) which was confirmed by 31P MRS of liver extracts in vitro (P < 0.005). Phosphodiester to ATP ratios were significantly increased (P < 0.05) in HL in vivo, but absolute PDE levels were similar in both groups. Phosphomonoester to ATP ratios did not change, although absolute phosphomonoester levels in HL were reduced by -41% (not significant). In HL extracts in vitro, sharp reductions in the levels of glucose-6-phosphate (P < 0.05), fructose-6-phosphate (P = 0.05), phosphocholine (P < 0.001), glycerophosphocholine (P < 0.001), and glycerophosphoethanolamine (P < 0.001) were observed. Electron microscopy revealed increased amounts and altered distribution of rough endoplasmic reticulum in HL. These findings show that experimental prostate cancer significantly affects hepatic phosphorylation status, phospholipid metabolism, and gluconeogenesis in the host animal, and demonstrate the value of combined MRS in vivo and in vitro in monitoring HL metabolism in cancer.     

Response of a non-Hodgkin lymphoma to 60Co therapy monitored by 31P MRS in situ

High quality 31P MR spectra (signal to noise ratio (S/N) approximately 18, 15 min acquisition for each spectrum) were consistently obtained with surface coils over a period of 6-week RT. Both transient and steady state alterations in metabolites in response to RT were found in this case. The transient changes occurred during the first 3 hr immediately after the 3rd fractionated RT, these changes include the transient elevation of the PCr resonance, a decrease in PDE and an increase in intracellular pH. The monitoring showed that the metabolites approached steady state approximately 2 hr after the fractionated radiation intervention, suggesting that in vivo MRS can be useful for studying the dynamics of tumor response to RT such as repair of potential lethal damage, growth delay, and reoxygenation etc. The steady-state MR spectra showed the net response to each intervention and can clinically be useful for predicting and measuring the result of the fractionated RT. In this case study, the PDE peak which contains the phospholipid metabolites GPC and GPE, is the most sensitive resonance in response to RT. After the 3rd RT, prior to tumor size reduction, the PDE to ATP ratio decreased 33% and intracellular pH increased to 7.34 +/- 0.05 from 7.27 +/- 0.05. In the subsequent RT interventions, both the tumor size and PDE/ATP ratio continually decreased whereas the pH values remained alkaline and fluctuated around 7.34 to 7.65. The data suggest that the phospholipid metabolite PDE may signal important alterations in membrane metabolism that eventually lead to cell death.     

Changes in Brain Energy and Membrane Metabolism in Glioblastoma following Chemoradiation

Brain parenchyma infiltration with glioblastoma (GB) cannot be entirely visualized by conventional magnetic resonance imaging (MRI). The aim of this study was to investigate changes in the energy and membrane metabolism measured with phosphorous MR spectroscopy (31P-MRS) in the presumably “normal-appearing” brain following chemoradiation therapy (CRT) in GB patients in comparison to healthy controls. Twenty (seven female, thirteen male) GB patients underwent a 31P-MRS scan prior to surgery (baseline) and after three months of standard CRT (follow-up examination. The regions of interest “contrast-enhancing (CE) tumor” (if present), “adjacent to the (former) tumor”, “ipsilateral distant” hemisphere, and “contralateral” hemisphere were compared, differentiating between patients with stable (SD) and progressive disease (PD). Metabolite ratios PCr/ATP, Pi/ATP, PCr/Pi, PME/PDE, PME/PCr, and PDE/ATP were investigated. In PD, energy and membrane metabolism in CE tumor areas have a tendency to “normalize” under therapy. In different “normal-appearing” brain areas of GB patients, the energy and membrane metabolism either “normalized” or were “disturbed”, in comparison to baseline or controls. Differences were also detected between patients with SD and PD. 31P-MRS might contribute as an additional imaging biomarker for outcome measurement, which remains to be investigated in a larger cohort.     

骨和软组织肿瘤的3.0T磁共振磷谱变化研究

目的 探讨骨和软组织肿瘤磁共振磷谱(31P-MRS)的变化特点.方法 对41例经病理证实的骨和软组织肿瘤患者的18个良性肿瘤病灶、28个恶性肿瘤病灶及其相邻部位正常肌肉组织,应用3.0T MR机进行31P-MRS分析,测量波谱中磷酸单酯(PME)、无机磷(Pi)、磷酸二酯(PDE)、磷酸肌酸(Pcr)、三磷酸腺苷γ-峰(γ-ATP)、α-峰(α-ATP)和β-峰(β-ATP)的峰下面积.分别以β-ATP、三磷酸核苷(NTP)和Pcr为参照,计算各代谢产物的相对比值.根据Pi相对于Pcr化学位移的变化计算细胞内pH值.结果 良、恶性肿瘤组中Pcr/PME、PME/NTP与正常对照组比较,差异均有统计学意义(P<0.05).良、恶性肿瘤组中PME/β-ATP与PME/NTP比较,差异有统计学意义(P<0.05).结论 Pcr/PME和PME/NTP是诊断骨和软组织肿瘤的潜在指标,PME/β-ATP和PME/NTP是鉴别骨和软组织肿瘤良、恶性的潜在指标.     

The effect of hypoxia and hyperoxia on nucleoside triphosphate/inorganic phosphate, pO2 and radiation response in an experimental tumour model.

This study has evaluated the effect of breathing 100% oxygen, carbogen and carbon monoxide (at 660 p.p.m.) on the bioenergetic and oxygenation status and the radiation response of 200-mm3 C3H mammary carcinomas grown in the feet of CDF mice. Bioenergetic status was assessed by 31P magnetic resonance spectroscopy (MRS) using a 7-tesla spectrometer with both short (2 s) and long (6 s) pulse repetition times. Tumour partial pressure of oxygen (PO2) was measured with an Eppendorf polarographic electrode; the oxygenation parameters were the median pO2 and fraction of pO2 values < or = 2.5 mmHg. The radiation response was estimated using a tumour growth delay assay (time to grow three times treatment volume). Carbon monoxide breathing decreased tumour pO2 and compromised the radiation response, but the beta-nucleoside triphosphate (NTP)/Pi ratio was unchanged. Both carbogen and oxygen (100%) increased tumour pO2 and beta-NTP/Pi and enhanced the radiation response, the effects being similar under the two gassing conditions and dependent on the gas breathing time. Thus, in this tumour model, 31P-MRS can detect hyperoxic changes, but because cells can remain metabolically active even at low oxygen tensions the beta-NTP/Pi did not correlate with low tissue oxygenation. An analysis of variance showed that gas breathing time induced a significant systematic effect on beta-NTP/Pi, the MRS pulse repetition time had a significant effect on beta-NTP/Pi change under hypoxic but not under hyperoxic conditions and the type of gas that was inhaled had a significant effect on beta-NTP/Pi.     

Magnetic Resonance Spectroscopy of cancer-practicalities of multi-centre trials and early results in non-Hodgkin's lymphoma

This review describes problems and solutions encountered in large scale multicentre trials of Magnetic Resonance Methods for monitoring cancer. It is illustrated with reference to the Multi-Institutional Group on Magnetic Resonance Spectroscopy (MRS) Applications to Cancer which was set up to perform a trial of 31P MRS for monitoring non-invasively chemotherapy of solid tumours. 31P MR spectra of non-Hodgkin's lymphoma (NHL) pre- and posttreatment, across nine Institutions, were acquired on either General Electric (GE) or Siemens 1.5T Clinical MR instruments. Development of the trial protocol, design of the Radio Frequency (RF) coils and Quality Control procedures necessary to ensure that the datasets acquired at each centre were comparable, are described. The data revealed that phosphomonoesters (PME)/nucleotide triphosphates (NTP) ratio decreased significantly after treatment in the Complete (P<0.001) and Partial (P<0.05) Responders but not in the Non-Responders (P>0.1). In addition, the PME/NTP ratio in the pre-treatment spectra correlated with the subsequent outcome of treatment indicating that PME/NTP levels are significant predictors of long-term clinical response and time-to-treatment failure in NHL.     

Evaluation of the effects of photodynamic therapy with phosphorus 31 magnetic resonance spectroscopy.

Magnetic resonance spectroscopy in situ was used to study changes in phosphorus 31 metabolism after photodynamic therapy (PDT) of transplanted HeLa cell tumours. Tumours were irradiated 2 h after administration of ATX-S10 (8-formyloximethylidene-7-hydroxy-3-ethenyl-2,7,12,18, tetramethyl-porphyrin-13,17-bispropionil aspartate), a new photosensitizer and chlorin derivative. Nuclear magnetic resonance spectra were measured prior to illumination and 1, 3, 7, 14, 21 and 28 days after PDT on each mouse. A drastic decrease in adenosine triphosphate (ATP) and a concomitant increase in inorganic phosphate (Pi) were evident on the first day after PDT in all cases. The beta-ATP/total phosphate (P) ratio was 0.64 +/- 0.29% (average +/- s.d.) in complete response, 0.67 +/- 0.30% in recurrence and 2.45 +/- 0.93% in partial response. Comparison of this ratio to the histological findings revealed that the beta-ATP/total P ratio reflects the HeLa cell tumours which survived PDT. In other words, partial response on the one hand was distinguished from complete response and recurrence on the other with this ratio 1 day after PDT (P < 0.05). In addition, the ratio of phosphomonoester (PME) to Pi rose beyond 1.0 when macroscopic recurrence occurred, while it stayed under 1.0 in complete response. This finding suggests that the recurrence of HeLa cell tumours can be detected by the PME/Pi ratio.