[CANCER RESEARCH 55, 3286-3294, August 1, 1995] Metabolic Characterization of Human Non-Hodgkin's Lymphomas in Vivo with the Use of Proton-decoupled Phosphorus Magnetic Resonance Spectroscopy1 William G. Negendank,2 Kristin A. Padavic-Slialler, Chun-Wei Li, Joseph Murphy-Boesch, Radka Stoyanova, Robert L. Krigel,3 Russell J. Schilder, Mitchell R. Smith, and Truman R. Brown Departments of Nuclear Magnetic Resonance and Medical Spectroscopy ¡W.C. N., K. A. P-S., C-W. L, J. M-B.. R. S.. T. R. B.I and Medical Oncology ¡R.L. K., R. J. S., M. R. S.¡.Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 ABSTRACT Development of biological and clinical uses of in vivo "I* magnetic resonance Spectroscopy has been hampered by poor anatomic localization of spectra and poor resolution of overlapping signals within phosphomo- noester and phosphodiester regions of the spectrum. We applied 'II- decoupling and nuclear Overhauser enhancement to improve resolution of "I1 magnetic resonance spectra accurately localized to 21 non-Hodgkin's lymphomas (NHL) by using three-dimensional chemical shift imaging. All 21 spectra had large phosphomonoester signals (26% of total phosphorus) that contained high amounts of phosphoethanolamine relative to phos- phocholine. There were no signals from glycerophosphoethanolamine or glycerophosphocholine but only a broad signal from membrane phospho- lipids in the phosphodiester region (20% of phosphorus). Prominent nucleoside triphosphates (47% of phosphorus) and low inorganic phos phate (7% of phosphorus) indicate well-perfused tissue with viable cells. Mean intracellular pH was 7.23. These characteristics were similar in all grades and stages of NHL. By analogy with recently reported studies in cell lines in vitro, we hypothesize that the pattern of phospholipid metab olites observed in NHL in vivo is partly a manifestation of sustained activation of phospholipase C or D. The techniques we implemented permitted us to obtain more information about in vivo metabolism of NHL than has heretofore been available. This information is important for the establishment of appropriate experimental models and provides a basis from which to examine potential clinical uses of 31P magnetic resonance Spectroscopy. INTRODUCTION NMR4 Spectroscopy (MRS) provides the ability to examine some aspects of metabolism in vivo in a noninvasive manner. A 31P NMR spectrum contains information about the amounts of phospholipid metabolites, NTP, and energy-related metabolites, as well as a means to measure intracellular pH. 31P NMR spectra of more than 200 human cancers in vivo have been reported, and results were reviewed recently (1). Cancers of a variety of tissue types typically had strong signal intensities in the PME and PDE regions and little or no signals from PCr. The mean pH, determined from the position of the P¡ signal on the frequency axis, was approximately 7.25. Studies in human cancer cell lines and transplanted murine tumors indicate that the nature and concentrations of PME and PDE phos pholipid metabolites are related to cell proliferation and tumor growth Received 2/8/95; accepted 5/31/95. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 Supported by NIH Grants ROI CA58632, ROI CA54339, and POI CA41078. 2 To whom requests for reprints should be addressed, at Department of Nuclear Magnetic Resonance and Medical Spectroscopy, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111. 3 Deceased, and to whose memory this paper is dedicated. 4 The abbreviations used are: NMR, nuclear magnetic resonance; MRS, magnetic resonance Spectroscopy; MRI, magnetic resonance imaging; PME, phosphomonoester; PDE, phosphodiester; NTP, nucleoside triphosphates; PCr, phosphocreatine; PEth, phos phoethanolamine; PChol, phosphocholine; GPEth, glycerophosphoethanolamine; GP- Chol, glycerophosphocholine; NOE, nuclear Overhauser effect; NHL, non-Hodgkin's lymphoma; CSI, chemical shift imaging; NDP, nucleoside diphosphate; DPG, 2,3-diphos- phoglycerate; DPDE, diphosphodiester; SAR, specific absorption rate; ppm. parts per million. (1), tumor cell death (2), and treatment sensitivity and resistance (3-5). However, the specific results of these studies have often been contradictory, and the concentrations of phospholipid metabolites are modulated by experimental conditions (6-12), making the relevance of experimental models to human cancers unclear. Therefore, it is important to know which metabolic characteristics occur in vivo in human cancers, not only to determine how closely metabolism in experimental models is analogous to metabolism in cancers in patients in clinical settings, but to pave the way for studies of clinical uses of MRS (1). The development of potential biological and clinical uses of in vivo 31P MRS has been hampered by a number of technical limitations: (a) poor anatomic localization of the NMR signals results in contam ination of the spectra by signals from tissues surrounding the region of interest. This situation is a problem particularly for cancers occurring within organs, such as liver, spleen, and brain, that contain large amounts of PMEs and PDEs. Poor localization introduces uncertainty in pH measurements because the position of P¡ may be taken relative to a metabolite (e.g., PCr) that is not actually contained within the cancer; and (b) poor resolution of overlapping signals makes it im possible to distinguish individual components within the PME region (e.g., PEth and PChol) and PDE region (e.g., GPEth and GPChol) or to distinguish GPEth and GPChol from immobile PDEs within phos- pholipids. One reason for the poor resolution of these metabolites is broadening of the 31P signals by coupling between the magnetic fields of 31P nuclei and those of nearby protons. This broadening may be eliminated by radiofrequency irradiation of protons during acquisition of the 3IP signal with the use of a 'H-decoupling technique, which is now feasible for use in vivo in human subjects (13). In addition, irradiation of protons between acquisitions can increase the 31P signal by NOE enhancement. The combination of 'H-decoupling and full NOE enhancement in vivo was recently implemented in 31P MRS studies of brain (14). We report the use of this technique, in conjunction with means to optimize the magnetic field homogeneity within the region of interest (shim ming), to improve resolution within the PME and PDE regions of the spectrum in patients with NHL. We used MRI-directed, three-dimen sional CSI to accurately localize 31P NMR spectra to regions of interest (15, 16). To permit application of these techniques in various anatomic sites, we constructed dual-tuned (31P, 'H) surface coil arrangements. This approach enabled us to obtain more information about the in vivo metabolic characteristics of NHL than has heretofore been available. The results provide stronger bases for the establish ment of appropriate experimental models of NHL and for the study of potential clinical uses of 31P MRS in this disease. MATERIALS AND METHODS Patient Population. Eligibility for study required a biopsy-proven diagno sis of NHL, a lymphoma-containing lymph node or mass of approximately 3-cm diameter or larger located within 10 cm of the surface of the body, absence of the standard contraindications to MRI, and signed informed consent as approved by the Institutional Review Board. One patient (case/) was unable lo tolerate the full 1.5-h study, but a high-quality nonlocalized spectrum was 3286 Research. on December 22, 2015. © 1995 American Association for Cancer cancerres.aacrjournals.org Downloaded from