Skip to main content
PMC home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2008 Dec 1.
Published in final edited form as: Acad Radiol. 2007 Dec;14(12):1531–1539. doi: 10.1016/j.acra.2007.07.012

In vivo Monitoring Response to Chemotherapy of Human Diffusion Large B-Cell Lymphoma Xenografts in SCID Mice by 1H and 31P MRS

MQ Huang, DS Nelson, S Pickup, H Qiao, EJ Delikatny, H Poptani, JD Glickson
PMCID: PMC2148497  NIHMSID: NIHMS35474  PMID: 18035282

Abstract

Rationale and Objectives

A reliable non-invasive method for in vivo detection of early therapeutic response of non-Hodgkin’s lymphoma (NHL) patients would be of great clinical value. This study evaluates the feasibility of 1H and 31P magnetic resonance spectroscopy (MRS) for in vivo detection of response to combination chemotherapy of human diffuse large B-cell lymphoma (DLCL2) xenografts in SCID mice.

Materials and Methods. C

ombination chemotherapy with Cyclophosphamide, Hydroxydoxorubicin, Oncovin, Prednisone, and Bryostatin 1 (CHOPB) was administered to tumor-bearing SCID mice weekly for up to four cycles. Spectroscopic studies were performed before the initiation of treatment and after each cycle of the CHOPB. Proton MRS for detection of lactate and total choline was performed using a selective multiple-quantum-coherence-transfer (Sel-MQC) and a spin-echo-enhanced Sel-MQC (SEE-Sel-MQC) pulse sequence, respectively. Phosphorus-31 MRS utilizing a non-localized single-pulse sequence without proton decoupling was performed on these animals.

Results

Significant decreases in lactate and total choline were detected in the DLCL2 tumors after one cycle of CHOPB chemotherapy. The ratio of phosphomonoesters to β-nucleoside triphosphate (PME/βNTP, measured by 31P MRS) significantly decreased in the CHOPB treated tumors after two cycles of CHOPB. The control tumors did not exhibit any significant changes in either of these metabolites.

Conclusions

This study demonstrates that 1H MRS and 31P MRS can detect in vivo therapeutic response of NHL tumors and that lactate and choline offer a number of advantages over PMEs as markers of early therapeutic response.

Keywords: Non-Hodgkin’s lymphoma, chemotherapy, therapeutic response, MRS, lactate, choline

Introduction

Non-Hodgkin’s lymphoma (NHL) comprises a heterogeneous group of closely related malignancies of the lymphoid system in which the cells usually express either B-cell or T-cell markers, or both (1–3). This disease results from disruption of normal development of the hematopoietic system at a precursor stage, probably due to immune deficiency, chronic inflammation, and chronic infection (2, 4). The incidence of NHL has been steeply rising (e.g., by 3% per annum in the USA), increasing by 90% in the past 50 years (5). An estimated 58,870 new cases of NHL are diagnosed in the United States annually. This disease ranks fifth and sixth in prevalence among cancers, and seventh and eighth as a cause of cancer death among females and males, respectively (6); however, in terms of prevalence and numbers of cancer deaths, it affects males more than females and Caucasians more than other races. Furthermore, NHL affects the younger and middle aged population and is the leading cause of cancer-related death among people between 20 and 40 years old; it ranks fourth among all cancers in terms of total number of productive years lost (4).

Currently, only a third of NHL cases are curable by standard chemotherapy (7). The availability of noninvasive methods for prediction and/or early detection of therapeutic response of NHL tumors would be of considerable clinical value. Such methods would facilitate the rational design and individualization of therapy protocols. This would spare non-responsive patients the unnecessary toxicity and expense of ineffective therapy and would offer them opportunities to explore more effective alternative treatment at an earlier time. However, an effective method of detecting early response of NHL to the wide range of therapeutic agents available for treatment of this disease remains elusive since sensitive and specific markers of therapeutic response are still not available.

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has become the standard of practice for the management of aggressive B-cell and indolent mantle cell lymphomas (8). PET images are routinely obtained before and after initiation of the first round of chemotherapy; a negative FDG PET scan is considered a strong predictor of prolonged disease-free survival. Although FDG PET offers higher sensitivity than anatomic imaging modalities, both MRI and CT offer higher spatial resolution and MR methods avoid ionizing radiation. Therefore, development of an MR-based method for early detection of therapeutic response is highly desirable.

The potential utility of in vivo magnetic resonance spectroscopy (MRS) for detection of therapeutic response of cancers has been explored by a number of investigators (9–17). In vivo 1H MRS detects a number of tumor phospholipid and bioenergetic metabolites associated with cell proliferation or degradation (9, 14, 18, 19). Phosphorus-31 MR spectra predominantly contain resonances of precursors and catabolites of membrane phospholipids, high-energy phosphates, and inorganic phosphate (17, 20–22). Thus, 31P-MRS has often been used to evaluate bioenergetic status and pH of tumors and to detect metabolic changes associated with changes in tumor perfusion and therapeutic response (21, 23). A multi-institutional clinical trial has recently demonstrated that pre-treatment 31P MRS of NHL tumors identified approximately two thirds of the NHL patients that subsequently failed to exhibit complete clinical response (i.e., disappearance of the local tumor) to a variety of therapeutic modalities (16, 24). The study suggests that proton-decoupled 31P MRS measurements of the phospholipid precursors phosphocholine (PC) and phosphoethanolamine (PE) normalized to total nucleoside triphosphates (NTP) serve as general predictors of therapeutic response failure for NHL. However, the low sensitivity and spatial resolution of 31P MRS compared to 1H MRS limits its clinical utility to relatively large superficial tumors (≥ 27 cm3 at 1.5 T or ≥ 10 cm3 at 3 T) (16). In contrast, 1H MRS can detect much smaller tumors (1–2 cm3 at 1.5 T) with the same signal-to-noise ratio as 31P MRS at the same acquisition time (25). Proton MRS has been demonstrated to be useful in differentiating between cancer, necrosis, and normal tissue of various organs such as brain (26–28), prostate (29), neck (28), breast (30, 31), kidney (32) and liver (33).

Mouse xenograft models of human NHL facilitate development of non-invasive techniques for serial assessment of therapeutic response. These methods hold great promise for tailor-fitting of therapeutic protocols to the needs of individual patients, for evaluating new therapeutic agents and for identification of therapeutic biomarkers. Studies of animal models serve as guides for clinical application of these methods.

In the present study, we have evaluated the utility of both 1H and 31P MRS for detecting response of mouse xenografts of human diffuse large B-cell lymphoma, the most common form of NHL, to combination chemotherapy with CHOPB (34). Bryostatin 1, an activator of protein kinase C, down-regulates the mdr1 gene, improving therapeutic response to CHOP (34, 35). This agent also exerts a modulatory effect on Bcl2 and p53 gene expression, thereby modifying drug sensitization (35).

Materials and Methods

Cell Line and Tumor Implantation

The Institutional Animal Care and Use Committee (IACUC) of the University of Pennsylvania approved all the procedures employed in these animal studies. The human WSU-DLCL2 cell line was initiated at Wayne State University and kindly supplied by Dr. Mohammad (34). WSU-DLCL2 cells were cultured in RPMI 1640 medium with 10% heat-inactivated fetal bovine serum (Hyclone, Rogan, UT), 1% penicillin/streptomycin (Invitrogen, Carlsbad, CA) and 1% HEPES (Mediatech, Inc., Herndon, VA). The cells were passaged 2–3 times a week and maintained under humidified 5% CO2 at 37°C. WSU-DLCL2 tumors were subcutaneously (s.c.) implanted in the upper thighs of 6–8 week old female SCID mice (NCI, Bethesda, MD) by inoculating 1.0×107 WSU-DLCL2 cells in 0.1 mL Hanks’ Balanced Salt Solution (Invitrogen/Gibco, Carlsbad, CA). Palpable tumors developed within a month. Tumor volume was measured twice a week with calipers and calculated as (π/6)×a×b×c, where a, b, and c are three orthogonal diameters. Magnetic resonance studies and chemotherapy were initiated when the tumor volume reached approximately 500 mm3. Animals were euthanized at the conclusion of the MR experiments or to avoid distress when the tumor burden reached 1,500 mm3.

Tumor Treatment

Tumor-bearing mice were treated once a week with CHOPB over a period of four weeks. Each cycle of CHOPB consisted of Cyclophosphamide (Baxter Healthcare Corporation, Deerfield, IL), intravenous (i.v.) injection at a dose of 40 mg/kg in a 20 mg/ml solution on Day 1; Hydroxydoxorubicin (Bed Venue Laboratories, Inc., Bedford, OH), i.v. at 3.3 mg/kg in a 2 mg/ml solution (Day 1); Oncovin (SICOR Pharmaceuticals, Inc., Irvine, CA), i.v. at 0.5 mg/kg in a 1 mg/ml solution (Day 1); Prednisone (Mathew J. Ryan Veterinary Hospital Pharmacy, Philadelphia, PA), per os (p.o.) at a dose of 0.2 mg/kg in a 0.1 mg/ml saline solution (Days 1–5); and Bryostatin 1 (Biomol International LP., Plymouth Meeting, PA), intraperitoneal (i.p.) at a dose of 75 μg/kg, in a 38 μg/ml saline solution (Day 1). The three i.v. drugs were mixed together and administered in a single tail vein injection. Control tumor bearing animals (n=5) were sham-treated with saline.

A strict regimen of aseptic cleaning of the site of injection, placement of injection sites at different positions in the tail, and gentle and slow injection of the fluid, was used to avoid extravasation of caustic drugs by multiple tail vein injections that can cause infection and necrosis in the tail.

1H and 31P MRS Studies

MR experiments were performed before treatment and after completion of each cycle for three cycles (three weeks) following initiation of treatment. During all MRS studies, the mice were anesthetized with 1.0–1.5% isoflurane in oxygen administered at a flow rate of 1 L/min through a nose cone. An MR-compatible small animal monitoring system with a rectal fiber-optic temperature probe (Luxtron, Mountain View, CA) was used to record the animal body temperature, which was maintained at 36.8°C by blowing warm air through the magnet bore.

In vivo MRS was performed on an Oxford 9.4 T/8.9 cm vertical bore NMR spectrometer equipped with a 25-gauss/cm and 55 mm ID gradient set (Resonance Research, Inc., Billerica, MA) and interfaced to a Varian Inova console (Palo Alto, CA). A home-built slotted-tube resonator (inner diameter of 14 mm and depth of 12 mm) dual-tuned for 1H and 31P was used for RF transmission and detection. Tumor-bearing mice were placed into the RF probe with the tumor taped to the center of the resonator. A selective multiple-quantum coherence (Sel-MQC) sequence (36) was used to measure global steady-state lactate of tumors and completely suppress lipid and water. A spin-echo-enhanced Sel-MQC (SEE-Sel-MQC) sequence was designed for simultaneous detection of lactate and choline (37). It is, however, difficult to optimize this sequence for both lactate and choline. Therefore, the SEE-Sel-MQC sequence was optimized for detection of choline only.

Typical parameters of the SEE-Sel-MQC sequence were: spectral width, 4 kHz; number of complex data points (np), 2048; repetition time, 4 s; number of averages, 64, and acquisition time, 4′55″. The parameters used for the Sel-MQC sequence were: spectral width, 4 kHz; number of complex data points (np), 4096; repetition time, 1 s; number of averages, 128; and acquisition time, 3′33″. The MR integral of lactate and total choline were first normalized to the unsaturated water signal measured with a single pulse-acquire sequence in the same study and then to the first data point from each group.

To evaluate tumor phosphorus metabolism, non-localized 31P MRS was performed using a single-pulse sequence with spectral width, 7 kHz; complex data points (np), 4096; repetition time, 1 s; number of averages, 256; and acquisition time, 5′32Prime;.

Data were processed with NUTS software (Acorn NMR Inc., Livermore, CA). An exponential filter with 5 Hz line broadening was employed to improve the apparent signal to noise ratio. Baseline correction was applied to MR spectra before calculating MR integral.

Statistical Analysis

Data from control and CHOPB treated tumors were compared by Student’s T-test analysis. A P-value ≤0.03 was considered statistically significant. Data are presented as mean ± standard error.

Results

Tumor Growth Delay

Figure 1 displays the time course of average tumor volume (N=5) over a period starting three days before and during CHOPB chemotherapy for up to four cycles of treatment. For each cycle, there were three measurements, one before the cycle, one in the middle of the cycle and one after the cycle with a single measurement between two consecutive cycles. The average tumor volume of CHOPB treated animals increased from ~600 mm3 to 1000 mm3 by the middle of the first cycle then decreased by about 40% from the peak value of tumor volume; tumor volume then monotonically decreased slightly over the remainder of the four week treatment period. Control tumors exhibited a monotonic increase over the whole study period. Differences between volumes of controls and treated tumors were significant (p<0.03) after the first cycle of CHOPB (i.e., one week after initiation of therapy).

Figure 1.

Figure 1

Open in a new tab

Time dependence of DLCL2 tumor volume of the control tumors (dashed line) and CHOPB treated tumors (solid line).

1H MRS of Total Choline and Lactate

Proton MRS of lactate and total choline were performed to longitudinally track the therapeutic response of tumors to CHOPB treatment. Figure 2a displays representative MR spectra of the CHOPB treated tumors before treatment, and after three cycles of CHOPB, in which the peaks of choline and lactate are presented. The two spectra show that the total choline peak decreased dramatically but the lactate peak decreased only slightly, probably due to the sub-optimal settings of the sequence for detection of lactate. Figure 2b depicts the time course of the MR signal intensity of the total choline peak of the control (dashed line, n=4) and CHOPB treated tumors (solid line, n=4). Signal intensity of total choline in the treated tumors significantly decreased after the first cycle of CHOPB (1.0±0.17 in the beginning of the first CHOPB cycle vs. 0.35±0.04 after the first CHOPB cycle, p<0.03) and remained stable at a low level thereafter. Representative lactate spectra (from Sel-MQC sequence) of the CHOPB treated tumors before the treatment, and after three cycles of CHOPB are shown in Figure 3a. The peak of lactate diminished significantly in the spectrum after three cycles of CHOPB. Figure 3b displays the time course of the MR signal intensity of lactate of control and CHOPB treated tumors (n=4). Signal intensity of lactate in the treated tumors significantly decreased within a week after the initiation of CHOPB (1.0±0.02 pretreatment vs. 0.19±0.04 after the first cycle of CHOPB, p<0.03). However, MR signal intensity of lactate in the control tumors did not significantly change as indicated by the dashed line in Figure 3b.

Figure 2.

Figure 2

Open in a new tab

(a) Representative 1H MR spectra of total choline and lactate of the CHOPB treated tumors before the treatment, and after three cycles of CHOPB using the SEE-Sel-MQC sequence. (b) Time course of MR signal intensity of total choline (normalized to water signal then to the first data) in the control tumors (dashed line) and CHOPB treated tumors (solid line).

Figure 3.

Figure 3

Open in a new tab

(a) Representative in vivo lactate-edited 1H MR spectra of the CHOPB treated tumors before treatment, after two cycles of CHOPB using the Sel-MQC pulse sequence. (b) Time course of MR signal intensity of lactate (normalized to water signal then to the first data) in the control tumors (dashed line) and CHOPB treated tumors (solid line).

31P MRS of DLCL2 Tumors

Figure 4a presents a set of representative in vivo 31P MR spectra of the CHOPB treated tumors before treatment and after three cycles of CHOPB. A number of metabolites were observed in the 31P MR spectra of the tumors. The PME resonances originating from phosphoethanolamine (PE) and phosphocholine (PC), and the phosphodiester (PDE) resonances originating from glycerophosphoethanolamine (GPE) and glycerophosphocholine (GPC) were not well resolved due to proton coupling. Figure 4b depicts the time courses of the ratio of PME/βNTP of the control tumors (dashed line) and CHOPB treated tumors (solid line, n=4). The ratio of PME/βNTP exhibited statistically significant decreases after two cycles of CHOPB chemotherapy (from 1.0 ± 0.17 pre-CHOPB to 0.54±0.10 after two cycles of CHOPB, p<0.03). In the control tumors no statistically significant change was observed over the entire period of the treatment.

Figure 4.

Figure 4

Open in a new tab

(a) Representative in vivo 31P MR spectra of the CHOPB treated tumors before treatment, and after three cycles of CHOPB using non-decoupled one-pulse sequence. (b) Time courses of PME/βNTP of the control tumors (dashed line) and CHOPB treated tumors (solid line).

Discussions

Tumors generally exhibit much higher levels of total choline than normal tissues (38). Though the SEE-Sel-MQC is a non-localized sequence, contamination from choline originating from normal tissue was probably negligible because the tumors were positioned in the middle of the slotted tube resonator used for MRS study. Decreased total choline has been observed to accompany therapeutic response in models of human prostate cancer after radiation therapy (39), human breast cancer after neoadjuvant chemotherapy (40), and a radiation-induced fibrosarcoma after administration of a vascular-disrupting agent or nicotinamide (41, 42). We have detected a significant decrease in total choline of the CHOPB treated tumors after the first cycle of CHOPB. The level of this resonance remained low during the rest of the treatment. These data reflect the partial response of this tumor to chemotherapy, which is consistent with the tumor volume data in Fig. 1.

The MR signal intensity of lactate exhibited a significant decrease in the CHOPB treated DLCL2 tumors relative to control tumors within a week after the first cycle of CHOPB treatment. Lactate is generally elevated in cancer cells (43). Decreases in lactate have been reported in different tumors (e.g., radiation-induced fibrosarcoma (RIF-1) and a breast tumor model (EMT6)) after treatment with chemo- or radiation- therapy (44–47). As the end-product of anaerobic glycolysis, lactate probably decreases after treatment due to decreased glycolysis and/or increased lactate clearance. Using 13C MRS and the two-compartment model of Artemov et al. (48), Poptani et al. have analyzed the rate of glycolysis, and lactate washout in vivo of RIF-1 tumors, following i.v. administration of [1-13C] glucose (49). These authors detected a decrease in glycolytic rate and no change in lactate washout in those tumors after treatment with cyclophosphamide. In contrast, Rivenzon-Segal et al. using a physiological-metabolic model have shown that both the rates of glycolysis and lactate clearance decreased in MCF7 breast tumors after tamoxifen treatment (50). Other investigators have suggested that the decrease in lactate level may result from decreased glycolysis, cell death, improved perfusion and/or tumor reoxygenation (45, 51). The decrease in tumor cell density of DLCL2 tumors observed in H & E stained sections that we report may reflect decreased tumor cell proliferation as indicated by Ki67 staining (M. Q. Huang et al., submitted) and could also be associated with increased perfusion due to decreases in interstitial pressure that usually accompany tumor cell death. Hence, elucidation of the mechanism underlying the decrease in tumor lactate that has been observed following CHOPB chemotherapy requires further study.

Since lymphoma cells usually have negligible PCr, and since muscle is the major source of PCr, the appearance of the phosphocreatine (PCr) peak in the tumor spectra can be attributed to muscle contamination (16, 24). The ratio of PME/βNTP in 31P MR spectra often decreases in responsive tumors following effective therapy (52). For example, the PME/βNTP ratio of responsive NHL human tumors decreased post-treatment (16). In the present study, the average PME/βNTP of the CHOPB treated tumors significantly decreased after two cycles of CHOPB, which indicates therapeutic response of the treated tumors. Phosphorus-31 MRS appears to detect response later than 1H MRS in these NHL tumors. Though the acquisition time of each 31P MR spectrum was one and a half times as long as that required for 1H MRS, the signal to noise ratio of 1H MR spectra is much higher than that of 31P spectra. Therefore, the utility of PME/βNTP as a response marker is limited by the relatively low sensitivity of 31P MRS. Our study suggests that 1H MRS of lactate and total choline may provide a more robust method for response detection.

Decrease in tumor volume is a direct index of therapeutic response. However, 1H MRS provides other indirect indices of tumor response (e.g., lactate, total choline). Figure 5 evaluates the correlation between the changes of tumor volume and the changes in lactate, total choline and PME/βNTP of the CHOPB treated tumors. The correlation coefficients (and p-values) between the tumor volume change and the changes of lactate, total choline and PME/βNTP are 0.314 (0.54), 0.530 (0.36), and 0.528 (0.28), respectively, indicating that no correlation exists between the tumor volume change and the changes in MR metabolic indices of therapeutic response. However, 1H MRS of lactate and total choline can detect tumor response to CHOPB therapy approximately three days earlier than tumor volume measurement. This may be because metabolic changes may occur much earlier than morphological changes in the tumors receiving chemotherapy (53). Therefore, 1H MRS is capable of detecting tumor response to chemotherapy prior to volume changes.

Figure 5.

Figure 5

Open in a new tab

Plots of the volumes of the CHOPB treated tumors compared with the MR signal ratio of lactate/water (top), total choline/water (middle) and PME/βNTP (bottom) of the tumors. Each plot displays a correlation line between the tumor volume and the MR signal intensity ratio of lactate/water, total choline/water and PME/βNTP. The square of correlation coefficients (R2) is displayed in each legend.

In conclusion, this study has assessed the utility of 1H and 31P MRS for detecting in vivo response to CHOPB chemotherapy of DLCL2 xenografts in SCID mice. We have demonstrated that 1H and 31P MRS can detect therapeutic response of the DLCL2 tumors after one or two cycles of CHOPB, respectively. Thus, in this instance 1H MRS of lactate and choline detects response earlier than 31P MRS.

Acknowledgments

This study was supported by NIH grant R01-CA101700-01A1 (JDG). The authors thank Dr. Steven Schuster at Hospital of the University of Pennsylvania for constructive discussion of clinical and experimental issues related to NHL. The MRS experiments in this study were performed in the Small Animal Imaging Facility, the Department of Radiology at the University of Pennsylvania.

Footnotes

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

References

  • 1.Ansell SM, Armitage J. Non-Hodgkin lymphoma: diagnosis and treatment. Mayo Clinic Proceedings. 2005;80:1087–1097. doi: 10.4065/80.8.1087. [DOI] [PubMed] [Google Scholar]
  • 2.Rogers BB. Overview of non-Hodgkin’s lymphoma. Seminars in Oncology Nursing. 2006;22:67–72. doi: 10.1016/j.soncn.2006.01.002. [DOI] [PubMed] [Google Scholar]
  • 3.Zinzani PL. Lymphoma: Diagnosis, Staging, Natural History, and Treatment Strategies. Seminars in Oncology. 2005;32:S4–S10. doi: 10.1053/j.seminoncol.2005.01.008. [DOI] [PubMed] [Google Scholar]
  • 4.Jazirehi AR, Bonavida B. Cellular and molecular signal transduction pathways modulated by rituximab (rituxan, anti-CD20mAb) in non-Hodgkin’s lymphoma: implications in chemosensitization and therapeutic intervention. Oncogene. 2005;24:2121–2143. doi: 10.1038/sj.onc.1208349. [DOI] [PubMed] [Google Scholar]
  • 5.American Cancer Society. Cancer Facts & Figures 2002. Atlanta: American Cancer Society; 2002. [Google Scholar]
  • 6.American Cancer Society. Cancer Facts & Figures 2006. Atlanta: American Cancer Society; 2006. [Google Scholar]
  • 7.Fisher R. Cyclophosphamide, doxorubicin, vincristine, and prednisone versus intensive chemotherapy in non-Hodgkin’s lymphoma. Cancer Chemother Pharmacol. 1997;40:S42–46. doi: 10.1007/s002800051060. [DOI] [PubMed] [Google Scholar]
  • 8.Juweid ME, Stroobants S, Hoekstra OS, et al. Use of positron emission tomography for response assessment of lymphoma: consensus of the Imaging Subcommittee of International Harmonization Project in Lymphoma. J Clin Oncol. 2007;25:571–578. doi: 10.1200/JCO.2006.08.2305. [DOI] [PubMed] [Google Scholar]
  • 9.Glickson JD. Clinical NMR-spectroscopy of tumors - Current status and future-directions. Investigative Radiology. 1989;24:1011–1016. doi: 10.1097/00004424-198912000-00020. [DOI] [PubMed] [Google Scholar]
  • 10.Ng TC, Evanochko WT, Hiramoto RN, et al. P-31 NMR-spectroscopy of In vivo tumors. J Magn Reson. 1982;49:271–286. [Google Scholar]
  • 11.Li SJ, Wehrle JP, Rajan SS, Steen RG, Glickson JD, Hilton J. Response of radiation-induced fibrosarcoma-1 in mice to cyclophosphamide monitored by in vivo P-31 nuclear magnetic-resonance spectroscopy. Cancer Research. 1988;48:4736–4742. [PubMed] [Google Scholar]
  • 12.Wehrle JP, Li SJ, Rajan SS, Steen RG, Glickson JD. P-31 and H-1-NMR spectroscopy of tumors In vivo - Untreated growth and response to chemotherapy. Annals of the New York Academy of Sciences. 1987;508:200–215. doi: 10.1111/j.1749-6632.1987.tb32905.x. [DOI] [PubMed] [Google Scholar]
  • 13.Braunschweiger PG, Kumar N, Constantinidis I, et al. Potentiation of interleukin 1-Alpha mediated antitumor effects by ketoconazole. Cancer Research. 1990;50:4709–4717. [PubMed] [Google Scholar]
  • 14.Shungu DC, Bhujwalla ZM, Wehrle JP, Glickson JD. H-1-NMR spectroscopy of subcutaneous tumors in mice - Preliminary studies of effects of growth, chemotherapy and blood-flow reduction. NMR in Biomedicine. 1992;5:296–302. doi: 10.1002/nbm.1940050517. [DOI] [PubMed] [Google Scholar]
  • 15.Bhujwalla ZM, Glickson JD. Detection of tumor response to radiation therapy by in vivo proton MR spectroscopy. International Journal of Radiation Oncology Biology Physics. 1996;36:635–639. doi: 10.1016/s0360-3016(96)00371-9. [DOI] [PubMed] [Google Scholar]
  • 16.Griffiths JR, Tate AR, Howe FA Stubbs as part of The Multi-Institutional Group on MRS Application to Cancer. Magnetic Resonance Spectroscopy of cancer—practicalities of multi-centre trials and early results in non-Hodgkin’s lymphoma. European Journal of Cancer. 2002;38:2085–2093. doi: 10.1016/s0959-8049(02)00389-1. [DOI] [PubMed] [Google Scholar]
  • 17.Zakian KL, Koutcher JA. Magnetic resonance spectroscopy and clinical cancer prognosis. Academic Radiology. 2004;11:365–367. doi: 10.1016/j.acra.2004.02.004. [DOI] [PubMed] [Google Scholar]
  • 18.Sibtaina NA, Howeb FA, Saundersc DE. The clinical value of proton magnetic resonance spectroscopy in adult brain tumours. Clinical Radiology. 2007;62:109–119. doi: 10.1016/j.crad.2006.09.012. [DOI] [PubMed] [Google Scholar]
  • 19.He Q, Shungu DC, van Zijl PC, Bhujwalla ZM, Glickson JD. Single-scan in vivo lactate editing with complete lipid and water suppression by selective multiple-quantum-coherence transfer (Sel-MQC)with application to tumors. J Magn Reson B. 1995;106:203–211. doi: 10.1006/jmrb.1995.1035. [DOI] [PubMed] [Google Scholar]
  • 20.Evanochko WT, Sakai TT, Ng TC, et al. NMR-study of in vivo Rif-1 tumors -analysis of perchloric-acid extracts and identification of H-1-resonances, P-31-resonances and C-13-resonances. Biochimica Et Biophysica Acta. 1984;805:104–116. doi: 10.1016/0167-4889(84)90042-9. [DOI] [PubMed] [Google Scholar]
  • 21.Evelhoch JL, Sapareto SA, Nussbaum GH, Ackerman JJH. Correlations between P-31 NMR-spectroscopy and O-15 perfusion measurements in the Rif-1 murine tumor in vivo. Radiation Research. 1986;106:122–131. [PubMed] [Google Scholar]
  • 22.Negendank WG, Padavicshaller KA, Li CW, et al. Metabolic characterization of human non-hodgkins-lymphomas in-vivo with the use of proton-decoupled phosphorus magnetic-resonance spectroscopy. Cancer Research. 1995;55:3286–3294. [PubMed] [Google Scholar]
  • 23.McPhail LD, Chung Y-L, Madhu B, et al. Tumor Dose Response to the Vascular Disrupting Agent,5,6-Dimethylxanthenone-4-Acetic Acid, Using In vivo Magnetic Resonance Spectroscopy. Clin Cancer Res. 2005;11:3705–3713. doi: 10.1158/1078-0432.CCR-04-2504. [DOI] [PubMed] [Google Scholar]
  • 24.Arias-Mendoza F, Smith MR, Brown TR. Predicting treatment response in non-Hodgkin’s lymphoma from the pretreatment tumor content of phosphoethanolamine plus phosphocholine. Academic Radiology. 2004;11:368–376. doi: 10.1016/s1076-6332(03)00721-9. [DOI] [PubMed] [Google Scholar]
  • 25.Bourne RM, Stanwell P, Stretch JR, et al. In vivo and ex vivo proton MR spectroscopy of primary and secondary melanoma. European Journal of Radiology. 2005;53:506–513. doi: 10.1016/j.ejrad.2004.03.016. [DOI] [PubMed] [Google Scholar]
  • 26.Chang L, Miller BL, McBride D, et al. Brain lesions in patients with AIDS: H-1 MR spectroscopy. Radiology. 1995;197:525–531. doi: 10.1148/radiology.197.2.7480706. [DOI] [PubMed] [Google Scholar]
  • 27.Panigrahy A, Krieger MD, Gonzalez-Gomez I, et al. Untreated pediatric primitive neuroectodermal tumor in vivo: quantitation of taurine with MR Spectroscopy. Radiology. 2005;236:1020–1025. doi: 10.1148/radiol.2363040856. [DOI] [PubMed] [Google Scholar]
  • 28.Star-Lack J, Spielman D, Adalsteinsson E, Kurhanewicz J, Terris DJ, Vigneron DB. In vivo lactate editing with simultaneous detection of choline, creatine, NAA, and lipid singlets at 1. 5 T using PRESS excitation with applications to the study of brain and head and neck tumors. J Magn Reson B. 1998;133:243–254. doi: 10.1006/jmre.1998.1458. [DOI] [PubMed] [Google Scholar]
  • 29.Kurhanewicz J, Vigneron DB, Hricak H, Narayan P, Carroll P, Nelson SJ. Three-dimensional H-1 MR spectroscopic imaging of the in situ human prostate with high (0.24-0.7-cm3) spatial resolution. Radiology. 1996;198:795–805. doi: 10.1148/radiology.198.3.8628874. [DOI] [PubMed] [Google Scholar]
  • 30.Stanwell P, Gluch L, Clark D, et al. Specificity of choline metabolites for in vivo diagnosis of breast cancer using 1H MRS at 1.5 T. Eur Radiol. 2005;15:1037–1043. doi: 10.1007/s00330-004-2475-1. [DOI] [PubMed] [Google Scholar]
  • 31.Mackinnon WB, Barry PA, Malycha PL, et al. Fine-needle biopsy specimens of benign breast lesions distinguished from invasive cancer ex vivo with proton MR spectroscopy. Radiology. 1997;204:661–666. doi: 10.1148/radiology.204.3.9280241. [DOI] [PubMed] [Google Scholar]
  • 32.Dixon RM, Frahm J. Localized proton MR spectroscopy of the human kidney in vivo by means of short echo time STEAM sequences. Magn Reson Med. 1994;31:482–487. doi: 10.1002/mrm.1910310503. [DOI] [PubMed] [Google Scholar]
  • 33.Tyszka JM, Silverman JM. Navigated single-voxel proton spectroscopy of the human liver. Magn Reson Med. 1998;39:1–5. doi: 10.1002/mrm.1910390102. [DOI] [PubMed] [Google Scholar]
  • 34.Mohammad RM, Wall NR, Dutcher JA, Al-Katib AM. The addition of Bryostatin 1 to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy improves response in a CHOP-resistant Human diffuse large cell lymphoma xenograft model. Clinical Cancer Research. 2000;6:4950–4956. [PubMed] [Google Scholar]
  • 35.Al-Katib AM, Smith MR, Kamanda WS, et al. Bryostatin 1 down-regulates mdr1 and potentiates vincristine cytotoxicity in diffuse large cell lymphoma xenografts. Clin Cancer Res. 1998;4:1305–1314. [PubMed] [Google Scholar]
  • 36.He Q, Shungu DC, van Zijl PC, Bhujwalla ZM, Glickson JD. Single-scan in vivo lactate editing with complete lipid and water suppression by selective multiple-quantum-coherence transfer (Sel-MQC)with application to tumors. J Magn Reson B. 1995;106:203–211. doi: 10.1006/jmrb.1995.1035. [DOI] [PubMed] [Google Scholar]
  • 37.He Q, Bhujwalla ZM, Glickson JD. Proton detection of choline and lactate in EMT6 tumors by spin-echo-enhanced selective multiple-quantum-coherence transfer. J Magn Reson B. 1996;112:18–25. doi: 10.1006/jmrb.1996.0104. [DOI] [PubMed] [Google Scholar]
  • 38.Ackerstaff E, Glunde K, Bhujwalla ZM. Choline phospholipid metabolism: a target in cancer cells? J Cell Biochem. 2003;90:525–533. doi: 10.1002/jcb.10659. [DOI] [PubMed] [Google Scholar]
  • 39.Dyke JP, Zakian KL, Spees WM, et al. Metabolic response of the CWR22 prostate tumor xenograft after 20 Gy of radiation studied by 1H spectroscopic imaging. Clin Cancer Res. 2003;9:4529–4536. [PubMed] [Google Scholar]
  • 40.Jagannathan NR, Kumar M, Seenu V, et al. Evaluation of total choline from in-vivo volume localized proton MR spectroscopy and its response to neoadjuvant chemotherapy in locally advanced breast cancer. Br J Cancer. 2001;84:1016–1022. doi: 10.1054/bjoc.2000.1711. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 41.Bhujwalla ZM, Shungu DC, Glickson JD. Effects of blood flow modifiers on tumor metabolism observed in vivo by proton magnetic resonance spectroscopic imaging. Magn Reson Med. 1996;36:204–211. doi: 10.1002/mrm.1910360206. [DOI] [PubMed] [Google Scholar]
  • 42.Madhu B, Waterton JC, Griffiths JR, Ryan AJ, Robinson SP. The response of RIF-1 fibrosarcomas to the vascular-disrupting agent ZD6126 assessed by in vivo and ex vivo 1H magnetic resonance spectroscopy. Neoplasia. 2006;8:560–567. doi: 10.1593/neo.06319. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 43.Warburg O. On the origin of cancer cells. Science. 1956;123:309–314. doi: 10.1126/science.123.3191.309. [DOI] [PubMed] [Google Scholar]
  • 44.Bhujwalla ZM, Glickson JD. Detection of tumor response to radiation therapy by in vivo proton MR spectroscopy. Int J Radiat Oncol Biol Phys. 1996;36:635–639. doi: 10.1016/s0360-3016(96)00371-9. [DOI] [PubMed] [Google Scholar]
  • 45.Poptani H, Bansal N, Graham RA, Mancuso A, Nelson DS, JD G. Detecting early response to cyclophosphamide treatment of RIF-1 tumors using selective multiple quantum spectroscopy (SelMQC) and dynamic contrast enhanced imaging. NMR Biomed. 2003;16:102–111. doi: 10.1002/nbm.816. [DOI] [PubMed] [Google Scholar]
  • 46.Aboagye EO, Bhujwalla ZM, Shungu DC, JD G. Detection of tumor response to chemotherapy by 1H nuclear magnetic resonance spectroscopy: effect of 5-fluorouracil on lactate levels in radiation-induced fibrosarcoma 1 tumors. Cancer Research. 1998;58:1063–1067. [PubMed] [Google Scholar]
  • 47.Aboagye EO, Bhujwalla ZM, He Q, Glickson JD. Evaluation of lactate as a 1H nuclear magnetic resonance spectroscopy index for noninvasive prediction and early detection of tumor response to radiation therapy in EMT6 tumors. Radiat Res. 1998;150:38–42. [PubMed] [Google Scholar]
  • 48.Artemov D, Bhujwalla ZM, Pilatus U, Glickson JD. Two-compartment model for determination of glycolytic rates of solid tumors by in vivo 13C NMR spectroscopy. NMR Biomed. 1998;11:395–404. doi: 10.1002/(sici)1099-1492(199812)11:8<395::aid-nbm536>3.0.co;2-r. [DOI] [PubMed] [Google Scholar]
  • 49.Poptani H, Bansal N, Jenkins WT, et al. Cyclophosphamide treatment modifies tumor oxygenation and glycolytic rates of RIF-1 tumors: 13C magnetic resonance spectroscopy, Eppendorf electrode, and redox scanning. Cancer Research. 2003;63:8813–8820. [PubMed] [Google Scholar]
  • 50.Rivenzon-Segal D, Margalit R, Degani H. Glycolysis as a metabolic marker in orthotopic breast cancer, monitored by in vivo (13)C MRS. Am J Physiol Endocrinol Metab. 2002;283:E623–630. doi: 10.1152/ajpendo.00050.2002. [DOI] [PubMed] [Google Scholar]
  • 51.Bhujwalla ZM, Shungu DCJDG. Effects of blood flow modifiers on tumor metabolism observed in vivo by proton magnetic resonance spectroscopic imaging. Magn Reson Med. 1996;36:204–211. doi: 10.1002/mrm.1910360206. [DOI] [PubMed] [Google Scholar]
  • 52.Negendank W. Studies of human tumors by MRS: a review. NMR Biomed. 1992;5:303–324. doi: 10.1002/nbm.1940050518. [DOI] [PubMed] [Google Scholar]
  • 53.Kumar M, Jagannathan NR, Seenu V, Dwivedi SN, Julka PK, Rath GK. Monitoring the therapeutic response of locally advanced breast cancer patients: sequential in vivo proton MR spectroscopy study. J Magn Reson Imaging. 2006;24:325–332. doi: 10.1002/jmri.20646. [DOI] [PubMed] [Google Scholar]

RESOURCES