Phosphorus MR spectroscopy in the treatment of human extremity sarcomas

Alkaline pH in intracranial tuberculomas: A 31Phosphorus magnetic resonance spectroscopy study

Objectives

Intracranial tuberculomas are one of the common causes of space-occupying lesions of the brain in developing countries. Proton (1H) magnetic resonance spectroscopy (MRS) has shown lipid peak in intracranial tuberculomas as a characteristic feature. Phosphorus (31P) MRS has been used to evaluate intracranial lesions and to calculate tissue pH non-invasively. The aim of this study is to evaluate intracranial tuberculomas using 31PMRS.

Materials and Methods

Intracranial tuberculomas proven by stereotactic or surgical biopsy were included in the study. After routine T1- and T2-weighted sequences, 31P MRS was performed using single-voxel intravoxel in vivo spectroscopy (ISIS) technique in the central core of the tuberculoma (voxel size 1-2 mm3). The pH was estimated using Petroff 's method using the chemical shift between phosphocreatine and Pi.

Results

31P MRS was available for 26 patients, in which there was significant positive correlation between high-energy phosphate metabolites, (markers of bioenergetic status), and low-energy phosphate metabolites (membrane phospholipids and inorganic phosphate). The calculated pH was slightly alkaline and varied from 6.97 to 7.22.

Conclusion

Intracranial tuberculomas showed alkaline pH in 31P MRS and this may be useful in the characterization of these lesions and possibly also in their treatment.

Effects of pluronic and doxorubicin on drug uptake, cellular metabolism, apoptosis and tumor inhibition in animal models of MDR cancers

Cancer chemotherapy is believed to be impeded by multidrug resistance (MDR). Pluronic (triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), PEO-b-PPO-b-PEO) were previously shown to sensitize MDR tumors to antineoplastic agents. This study uses animal models of Lewis lung carcinoma (3LL-M27) and T-lymphocytic leukemia (P388/ADR and P388) derived solid tumors to delineate mechanisms of sensitization of MDR tumors by Pluronic P85 (P85) in vivo. First, non-invasive single photon emission computed tomography (SPECT) and tumor tissue radioactivity sampling demonstrate that intravenous co-administration of P85 with a Pgp substrate, 99Tc-sestamibi, greatly increases the tumor uptake of this substrate in the MDR tumors. Second, 31P magnetic resonance spectroscopy (31P-MRS) in live animals and tumor tissue sampling for ATP suggest that P85 and doxorubicin (Dox) formulations induce pronounced ATP depletion in MDR tumors. Third, these formulations are shown to increase tumor apoptosis in vivo by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and reverse transcription polymerase chain reaction (RT-PCR) for caspases 8 and 9. Altogether, formulation of Dox with P85 results in increased inhibition of the growth solid tumors in mice and represents novel and promising strategy for therapy of drug resistant cancers.

Imaging and Response in Soft Tissue Sarcomas

Conventional CT and MRI scans provide exquisite anatomic detail of soft tissue sarcomas but fall short of estimating the degree of tumor viability within a sarcomatous mass. Functional imaging methods that measure biologic properties within sarcomas may be better able to determine true tumor responses to chemotherapy or radiotherapy. Many different approaches to measure biologic processes have been taken and are discussed, but positron emission tomography (PET) is currently the most quantitative and developed. A response in tumor glucose uptake, determined by PET, has been shown to correlate with improved clinical outcomes in high-grade extremity soft tissue sarcomas and gastrointestinal stromal tumors. Functional imaging of soft tissue sarcomas may prove to be useful clinically, therefore further investigation is warranted.

The role of imaging in the staging and treatment planning of primary malignant bone tumors in children

The accurate staging of primary bone tumors in children is critical for treatment planning. Limb salvage operations can now be performed with excellent outcomes in suitable patients. The purpose of this article is to review the current state of imaging techniques and their roles in enabling accurate staging and treatment planning to be performed in pediatric patients with primary bone tumors.

Techniques to modulate radiotherapy toxicity and outcome in soft tissue sarcoma

Radiotherapy (RT) targeting of soft tissue sarcoma presents considerable opportunity and challenges in realizing the dual goals of tissue and function preservation and maintaining high local control. Traditional RT target volumes used for soft tissue sarcoma have largely been constrained by available technology and are not ideal in some situations. The advent of very precise treatment planning and delivery systems, including three-dimensional conformal radiotherapy and intensity-modulated radiotherapy, means it is possible to select target volumes that more closely approach the optimum. Consequently, these new approaches provide great opportunity for treatment enhancement in the future. It can be expected that newer techniques for RT planning and delivery will challenge the existing dogma concerning target delineation for optimal radiotherapy outcome. It can be foreseen that the precise knowledge of appropriate targets will continue to evolve for different clinical scenarios and likely be greatly influenced by enhanced imaging capability. Advancement of three-dimensional conformal radiotherapy and intensity-modulated radiotherapy over the next decade must rely on the consistent reporting and sharing of results concerning outcome of normal tissue from volumetric treatment planning.

Phosphorous metabolites and steady-state energetics of transformed fibroblasts during three-dimensional growth

Rat1-T1 and MR1 spheroids represent separate transformed phenotypes originated from the same rat fibroblasts that differ in three-dimensional (3D) growth kinetics, histological structure, and oxygenation status. In the present study, (31)P-NMR spectroscopy of perfused spheroid suspensions was used to investigate cellular energetics relative to 3D growth, development of necrosis, and cell cycle distribution. Both spheroid types were characterized by a remarkably low amount of free (inorganic) phosphate (P(i)) and a low phosphocreatine peak. The ratio of nucleoside triphosphate (NTP) to P(i) ranged between 1.5 and 2.0. Intracellular pH, NTP-to-P(i) ratio, and NTP/cell remained constant throughout spheroid growth, being unaffected by the emergence of oxygen deficiency, cell quiescence, and necrosis. However, a 50% decrease in the ratio of the lipid precursors phosphorylcholine and phosphorylethanolamine (PC/PE) was observed with increasing spheroid size and was correlated with an increased G(1)/G(0) phase cell fraction. In addition, the ratio of the phospholipid degradation products glycerophosphorylcholine and glycerophosphorylethanolamine (GPC/GPE) increased with spheroid diameter in Rat1-T1 aggregates. We conclude that changes in phospholipid metabolism, rather than alterations in energy-rich phosphates, reflect cell quiescence in spheroid cultures, because cells in the inner oxygen-deficient zones seem to adapt their energy metabolism to the environmental conditions before necrotic cell destruction.

Long-term assessment of posttransplant renal prognosis with 31 P magnetic resonance spectroscopy

BACKGROUND

31P-magnetic resonance spectroscopy (MRS) has been widely used to study pretransplantation renal viability, and although some had discussed posttransplant renal viability, no one has examined long-term posttransplant renal prognosis. We discuss the use of 31P-MRS to assess the long-term prognosis from the time when MRS was performed.

METHODS

We studied 20 patients with renal allografts. 1.5 Tesla clinical magnetic resonance imaging (MRI) and 15 cm surface coil was used for 31P-MRS. Localized 31P-MRS was done using image selected in vivo spectroscopy (ISIS) method. Individual peaks were fitted by Lorenzian line-shapes with a least square method and peak area ratios were calculated.

RESULTS

A beta-adenosine triphosphate/inorganic phosphate (beta-ATP/Pi) ratio >1.2 had sensitivity of 92.8%, specificity of 100%, and accuracy of 95% for predicting 3-year renal survival; a beta-ATP/Pi ratio >1.2 had sensitivity of 90.9%, specificity of 66.7%, and accuracy of 76.9% for predicting 5-year renal survival. We compared 31P-MRS spectra data between the survived group and failed group. The survived group had significantly higher beta-ATP/Pi, alpha-ATP/Pi, and phosphodiester (PDE)/Pi ratios than the failed group.

CONCLUSIONS

We discussed the beta-ATP/Pi value as a parameter for predicting long-term survival of a transplanted kidney from the time when MRS was performed. A value above 1.2 suggests a high probability of 3-year renal survival, whereas a value over 2.5 indicates that the transplanted kidney could survive over 5 years. 31P-MRS may be useful for predicting long-term survival of transplanted kidneys, but additional studies are needed.

Phosphocholine and phosphoethanolamine during chick embryo myogenesis: a (31)P-NMR study

Elevated contents of phosphoethanolamine (Etn-P) and/or phosphocholine (Cho-P), a common feature of most tumours with respect to normal counterparts, may also occur in non-cancerous proliferating tissues. The significance of these alterations in relation to cell proliferation, differentiation and maturation is scarcely understood. In this work, the Cho-P and Etn-P pools were measured by (31)P-NMR in extracts of chick embryo pectoral muscle at different days of development. The average concentration of these metabolites exhibited the highest values (respectively, 1.5 and 3.0 micromol/mg DNA) on days 9-11 and decreased at later stages of myogenesis. While, however, Cho-P maintained substantial levels (above 1.0 micromol/mg DNA) also during myotube formation (days 11-18) and stepwise decreased (to about 0.5 micromol/mg DNA) upon fibres' maturation, Etn-P gradually decreased between day 11 and hatching time (down to about 0.2 micromol/mg DNA). These results demonstrate that significant changes may occur in the steady-state pools of these metabolites during normal in vivo cellular development and differentiation, and are consistent with: (a) high rates of phospholipid biosynthesis reported in the literature for proliferating myoblasts; (b) sustained phosphatidylcholine synthesis maintained also during myoblast fusion; and (c) decreased requirement of phospholipid synthesis in the last phase of in ovo myofibre maturation.

Tumour phospholipid metabolism

Following the impetus of early clinical and experimental investigations, in vivo and in vitro MRS studies of tumours pointed in the eighties to the possible significance of signals arising from phospholipid (PL) precursors and catabolites as novel biochemical indicators of in vivo tumour progression and response to therapy. In the present decade, MRS analyses of individual components contributing to the 31P PME (phosphomonoester) and PDE (phosphodiester) resonances, as well as to the 1H 'choline peak', have reinforced some of these expectations. Moreover, the absolute quantification of these signals provided the basis for addressing more specific (although still open) questions on the biochemical mechanisms responsible for the formation of intracellular pools of PL derivatives in tumours, under different conditions of cell proliferative status and/or malignancy level. This article is aimed at providing an overview on: (a) quantitative MRS measurements on the contents of phosphocholine (PCho), phosphoethanolamine (PEtn) and their glycerol derivatives ģlycerol 3-phosphocholine (GPC) and glycerol 3-phosphoethanolamine (GPE)[ in human tumours and cells (with particular attention to breast and brain cancer and lymphomas), as well as in normal mammalian tissues (including developing organs and rapidly proliferating tissues); (b) possible correlations of MRS parameters like PEtn/PCho and PCho/GPC ratios with in vitro cell growth status and/or cell tumorigenicity; and (c) current and new hypotheses on the role and interplay of biosynthetic and catabolic pathways of the choline and ethanolamine cycles in modulating the intracellular sizes of PCho and PEtn pools, either in response to mitogenic stimuli or in relation to malignant transformation.

Molecular aspects of magnetic resonance imaging and spectroscopy

Magnetic resonance imaging (MRI) is a well known diagnostic tool in radiology that produces unsurpassed images of the human body, in particular of soft tissue. However, the medical community is often not aware that MRI is an important yet limited segment of magnetic resonance (MR) or nuclear magnetic resonance (NMR) as this method is called in basic science. The tremendous morphological information of MR images sometimes conceal the fact that MR signals in general contain much more information, especially on processes on the molecular level. NMR is successfully used in physics, chemistry, and biology to explore and characterize chemical reactions, molecular conformations, biochemical pathways, solid state material, and many other applications that elucidate invisible characteristics of matter and tissue. In medical applications, knowledge of the molecular background of MRI and in particular MR spectroscopy (MRS) is an inevitable basis to understand molecular phenomenon leading to macroscopic effects visible in diagnostic images or spectra. This review shall provide the necessary background to comprehend molecular aspects of magnetic resonance applications in medicine. An introduction into the physical basics aims at an understanding of some of the molecular mechanisms without extended mathematical treatment. The MR typical terminology is explained such that reading of original MR publications could be facilitated for non-MR experts. Applications in MRI and MRS are intended to illustrate the consequences of molecular effects on images and spectra.