Dicarboxylic acids as pH sensors for hyperpolarized 13C magnetic resonance spectroscopic imaging.

Imaging tumoral pH may help to characterize aggressiveness, metastasis, and therapeutic response. We report the development of hyperpolarized [2-13C,D10]diethylmalonic acid, which exhibits a large pH-dependent 13C chemical shift over the physiological range. We demonstrate that co-polarization with [1-13C,D9]tert-butanol accurately measures pH via13C NMR and magnetic resonance spectroscopic imaging in phantoms.

The role of metabolic imaging in radiation therapy of prostate cancer.

The goal of this study was to correlate prostatic metabolite concentrations from snap-frozen patient biopsies of recurrent cancer after failed radiation therapy with histopathological findings, including Ki-67 immunohistochemistry and pathologic grade, in order to identify quantitative metabolic biomarkers that predict for residual aggressive versus indolent cancer. A total of 124 snap-frozen transrectal ultrasound (TRUS)-guided biopsies were acquired from 47 men with untreated prostate cancer and from 39 men with a rising prostate-specific antigen and recurrent prostate cancer following radiation therapy. Biopsy tissues with Ki-67 labeling index ≤ 5% were classified as indolent cancer, while biopsy tissues with Ki-67 labeling index > 5% were classified as aggressive cancer. The majority (15 out of 17) of cancers classified as aggressive had a primary Gleason 4 pattern (Gleason score ≥ 4 + 3). The concentrations of choline-containing phospholipid metabolites (PC, GPC, and free Cho) and lactate were significantly elevated in recurrent cancer relative to surrounding benign tissues. There was also a significant increase in [PC] and reduction in [GPC] between untreated and irradiated prostate cancer biopsies. The concentration of the choline-containing phospholipid metabolites was significantly higher in recurrent aggressive (≈ twofold) than in recurrent indolent cancer biopsies, and the receiver operating characteristic (ROC) curve analysis of total choline to creatine ratio (tCho/Cr) demonstrated an accuracy of 95% (confidence interval = 0.88-1.00) for predicting aggressive recurrent disease. The tCho/Cr was significantly higher for identifying recurrent aggressive versus indolent cancer (tCho/Cr = 2.4 ± 0.4 versus 1.5 ± 0.2), suggesting that use of a higher threshold tCho/Cr ratio in future in vivo (1)H MRSI studies could improve the selection and therapeutic planning for patients who would benefit most from salvage focal therapy after failed radiation therapy.

Multimodal wavelet embedding representation for data combination (MaWERiC): integrating magnetic resonance imaging and spectroscopy for prostate cancer detection.

Recently, both Magnetic Resonance (MR) Imaging (MRI) and Spectroscopy (MRS) have emerged as promising tools for detection of prostate cancer (CaP). However, due to the inherent dimensionality differences in MR imaging and spectral information, quantitative integration of T(2) weighted MRI (T(2)w MRI) and MRS for improved CaP detection has been a major challenge. In this paper, we present a novel computerized decision support system called multimodal wavelet embedding representation for data combination (MaWERiC) that employs, (i) wavelet theory to extract 171 Haar wavelet features from MRS and 54 Gabor features from T(2)w MRI, (ii) dimensionality reduction to individually project wavelet features from MRS and T(2)w MRI into a common reduced Eigen vector space, and (iii), a random forest classifier for automated prostate cancer detection on a per voxel basis from combined 1.5 T in vivo MRI and MRS. A total of 36 1.5 T endorectal in vivo T(2)w MRI and MRS patient studies were evaluated per voxel by MaWERiC using a three-fold cross validation approach over 25 iterations. Ground truth for evaluation of results was obtained by an expert radiologist annotations of prostate cancer on a per voxel basis who compared each MRI section with corresponding ex vivo wholemount histology sections with the disease extent mapped out on histology. Results suggest that MaWERiC based MRS T(2)w meta-classifier (mean AUC, µ = 0.89 ± 0.02) significantly outperformed (i) a T(2)w MRI (using wavelet texture features) classifier (µ = 0.55 ± 0.02), (ii) a MRS (using metabolite ratios) classifier (µ = 0.77 ± 0.03), (iii) a decision fusion classifier obtained by combining individual T(2)w MRI and MRS classifier outputs (µ = 0.85 ± 0.03), and (iv) a data combination method involving a combination of metabolic MRS and MR signal intensity features (µ = 0.66 ± 0.02).

Correlation of phospholipid metabolites with prostate cancer pathologic grade, proliferative status and surgical stage - impact of tissue environment.

This study investigates the relationship between phospholipid metabolite concentrations, Gleason score, rate of cellular proliferation and surgical stage in malignant prostatectomy samples by performing one- and two-dimensional, high-resolution magic angle spinning, total correlation spectroscopy, pathology and Ki-67 staining on the same surgical samples. At radical prostatectomy, surgical samples were obtained from 49 patients [41 with localized TNM stage T1 and T2, and eight with local cancer spread (TNM stage T3)]. Thirteen of the tissue samples were high-grade prostate cancer [Gleason score: 4 + 3 (n = 7); 4 + 4 (n = 6)], 22 low-grade prostate cancer [Gleason score: 3 + 3 (n = 17); 3 + 4 (n = 5)] and 14 benign prostate tissues. This study demonstrates that high-grade prostate cancer shows significantly higher Ki-67 staining and concentrations of phosphocholine (PC) and glycerophosphocholine (GPC) than does low-grade prostate cancer (2.4 ± 2.8% versus 7.6 ± 3.5%, p < 0.005, and 0.671 ± 0.461 versus 1.87 ± 2.15 mmolal, p < 0.005, respectively). In patients with local cancer spread, increases in [PC + GPC + PE + GPE] (PE, phosphoethanolamine; GPE, glycerophosphoethanolamine] and Ki-67 index approached significance (4.2 ± 2.5 versus 2.7 ± 2.4 mmolal, p = 0.07, and 5.3 ± 3.8% versus 2.9 ± 3.8%, p = 0.07, respectively). PC and Ki-67 were significantly lower and GPC higher in prostate tissues when compared with cell cultures, presumably because of a lack of important stromal-epithelial interactions in cell cultures. The findings of this study will need to be validated in a larger cohort of surgical patients with clinical outcome data, but support the role of in vivo (1)H MRSI in discriminating between low- and high-grade prostate cancer based on the magnitude of elevation of the in vivo total choline resonance.

Imaging considerations for in vivo 13C metabolic mapping using hyperpolarized 13C-pyruvate.

One of the challenges of optimizing signal-to-noise ratio (SNR) and image quality in (13)C metabolic imaging using hyperpolarized (13)C-pyruvate is associated with the different MR signal time-courses for pyruvate and its metabolic products, lactate and alanine. The impact of the acquisition time window, variation of flip angles, and order of phase encoding on SNR and image quality were evaluated in mathematical simulations and rat experiments, based on multishot fast chemical shift imaging (CSI) and three-dimensional echo-planar spectroscopic imaging (3DEPSI) sequences. The image timing was set to coincide with the peak production of lactate. The strategy of combining variable flip angles and centric phase encoding (cPE) improved image quality while retaining good SNR. In addition, two aspects of EPSI sampling strategies were explored: waveform design (flyback vs. symmetric EPSI) and spectral bandwidth (BW = 500 Hz vs. 267 Hz). Both symmetric EPSI and reduced BW trended toward increased SNR. The imaging strategies reported here can serve as guidance to other multishot spectroscopic imaging protocols for (13)C metabolic imaging applications.

DNP-Hyperpolarized C Magnetic Resonance Metabolic Imaging for Cancer Applications.

Critical factors in characterizing the aggressiveness and response to therapy for tumors are the availability of noninvasive biomarkers that can be combined with other clinical parameters to tailor treatment regimens to each individual patient. While conventional magnetic resonance (MR) images are widely used to estimate changes in tumor size, they do not provide the rapid readout that is required to make an early decision on whether a change in therapy is required. The use of hyperpolarized (13)C agents to obtain metabolic imaging data is of great interest for in vivo assessment of tumors. One of the first agents being considered for in vivo studies with dynamic nuclear polarization (DNP) is 1-(13)C-labeled pyruvate, which is converted to lactate or alanine, dependent upon the needs of the tissue in question. The development of this new technology and its implementation in preclinical cancer model systems has clearly demonstrated the potential for highlighting tumor aggressiveness and for monitoring changes associated with disease progression. While there is further work to do in terms of studying new agents, improving the DNP process itself and developing efficient MR methods for acquiring and analyzing the data, the preliminary results are extremely promising and provide strong motivation for considering cancer as one of the first applications of the technology.

Dynamic nuclear polarization of biocompatible (13)C-enriched carbonates for in vivo pH imaging.

A hyperpolarization technique using carbonate precursors of biocompatible molecules was found to yield high concentrations of hyperpolarized (13)C bicarbonate in solution. This approach enabled large signal gains for low-toxicity hyperpolarized (13)C pH imaging in a phantom and in vivo in a murine model of prostate cancer.

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

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

Static field intensity modulation to treat a dominant intra-prostatic lesion to 90 Gy compared to seven field 3-dimensional radiotherapy.

PURPOSE/OBJECTIVE: Recent studies supported by histopathological correlation suggest that the combined use of endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) allows differentiation of normal and carcinomatous prostate. The goal of this study was to use static field intensity modulated three-dimensional conformal radiotherapy (SF-IMRT) to treat the entire prostate to a total dose of >70 Gy, while concurrently treating a dominant intraprostatic lesion (DIL) defined by MRI+MRS to 90 Gy while not exceeding normal tissue tolerances. MATERIALS AND METHODS: For the example chosen, the DIL consisted of a large portion of the peripheral zone of the left lobe of the prostate. University of Michigan (UM-PLAN) three-dimensional treatment planning software was used to design a partially shielded 7 field conformal isodose plan that would treat the entire prostate to >70 Gy at 1.8 Gy per day (80% isodose line), while concurrently treating the DIL to 2.25 Gy per day for a total dose of 90 Gy. Dose volume histograms (DVH) were used to compare the rectal doses to rectum and other adjacent normal tissues using these two techniques. RESULTS: SF-IMRT as described, allowed a total dose of 90 Gy to encompass the DIL, while the rectal dose was slightly lower than that using the standard 7 field technique to the prostate alone. For example, the dose to 30 cm3 of the rectum was 40 Gy using SF-IMRT and 48 Gy for the standard 7 field technique. Because of differences in the dose per fraction the biologic advantages of the SF-IMRT technique are likely to be even greater. CONCLUSIONS: This study demonstrates the feasibility of using SF-IMRT to treat a DIL involving a single lobe of the prostate, as defined by MRI/MRS, to 90 Gy, while simultaneously treating the prostate to >70 Gy without increasing the dose to surrounding normal tissues. A similar approach could be used to treat multifocal disease. This method of treatment is an alternative to dynamic intensity modulation. It is less expensive, and can be adapted to any radiation therapy department without the use of an inverse treatment planning programs.

31P magnetic resonance spectroscopy (MRS) of experimental orbital myositis.

We described a model of orbital myositis that was induced by 12-0-tetradecanoyl-phorbol-13-acetate (TPA) injection into the superior rectus muscle of New Zealand white rabbits. In this study, in vivo 31P magnetic resonance spectroscopy (MRS) was performed with a 4.7 Tesla Oxford (Oxford Instruments, Oxford, England) magnet to monitor the evolution of muscle inflammation in control animals and the response of this model to external beam radiation. 31P MRS showed a dramatic increase in high-energy phosphorus and phospholipid metabolites 48 hr after TPA injection. These spectra were similar to those from implanted allogenic fibroblasts. Within 18-48 hr after a single dose (400 cGy) or sequential doses (3 days at 400 cGy) of orbital irradiation, reduced extraocular muscle swelling and a significant decrease of all 31P metabolites occurred. A decrease (63 +/- 6%) in the signal-to-noise (S/N) ratio of the control inflamed muscle 31P MR spectra increased by 28 days after inflammation. Two days after single-dose radiation, 31P MR metabolites were significantly lower (58 +/- 5%, P less than 0.012) than control spectra. These postradiation spectra mirror the 28-day control spectra and are consistent with previous histologic data that show decreased fibroblastic activity. Change in 31P MRS was a sensitive indicator of treatment response latency.

31P magnetic resonance spectroscopy of animal uveal melanoma.

Scleral surface coils were used to obtain in vivo magnetic resonance spectra (MRS) of Greene melanoma implanted in the rabbit uvea. Well-localized tumor spectra (4.7 Tesla) with good signal-to-noise ratios (S/N) were obtained from the tumor with a "single-pulse" sequence in less than 1 hour. Tumor localization was confirmed with one-dimensional spectroscopic imaging studies. Serial 31P spectra were obtained during tumor growth and after both optimal and suboptimal hyperthermia. Early 31P MRS change is correlated with tumor treatment response and preceded histologic evidence of cell destruction. Twenty-four to 48 hours after successful treatment, the inorganic phosphate/nucleoside triphosphate (NTP), and phosphomonoester/NTP ratios were significantly increased from 1.2 +/- 0.1 to 1.7 +/- 0.1 and 1.3 +/- 0.1 to 1.8 +/- 0.2, respectively. In contrast, untreated or ineffectively treated tumors showed little change. Interpretation of 31P MRS data in this animal uveal melanoma model after the first week was complicated by decreased S/N, increased contamination from contiguous tissues, ingrowth of fibroblasts, macrophages, and intratumor hemorrhage.

MRS of ischemic/hypoxic brain disease.

Significant increases in magnetic field strengths and improvements in magnetic field homogeneity have made combined high-resolution magnetic resonance imaging (MRI) and multinuclear spectroscopy (MRS) feasible for investigating the relationship between biochemical and structural changes induced by ischemic brain disease. Magnetic resonance spectroscopy is the only noninvasive technique capable of measuring concentrations of high-energy phosphate metabolites, lactate, and other metabolically relevant compounds. Anticipated advances in localization of the volume of tissue from which spectra are obtained will enhance the clinical potential of MRS in the diagnosis of ischemic disease.

Citrate as an in vivo marker to discriminate prostate cancer from benign prostatic hyperplasia and normal prostate peripheral zone: detection via localized proton spectroscopy.

OBJECTIVES: This study was designed to determine whether citrate levels detected by localized 1H spectroscopy could reliably discriminate regions of prostate adenocarcinoma from surrounding regions of normal peripheral zone and benign prostatic hyperplasia (BPH). METHODS: In 28 patients and 5 volunteers stimulated echo proton spectroscopy was used in conjunction with endorectal surface coils to obtain water-suppressed 1H spectra from regions of normal prostate peripheral zone, BPH, and prostate cancer. 1H spectra from prostate cancer patients were correlated with pathologic areas identified on T2-weighted endorectal coil magnetic resonance (MR) images and histologic study of the step-sectioned gland after surgery. RESULTS: The major finding of in vivo studies was consistently lower citrate levels in prostate cancer compared with BPH and normal prostate peripheral zone. This was reflected by significantly (P < 0.05) lower mean citrate/(creatine plus choline) peak area ratio observed for regions of cancer (0.67 +/- 0.17) compared with BPH (1.21 +/- 0.29) and normal peripheral zone (1.46 +/- 0.28). Moreover, there was no overlap of individual cancer and normal peripheral zone citrate ratios and no significant difference between citrate ratios in regions of normal peripheral zone in young volunteers (1.28 +/- 0.14) and age-matched patients (1.46 +/- 0.28). The observed alterations in vivo citrate levels were supported by citrate concentration data obtained from extracts of histologically proven samples of normal, benign, and malignant prostatic tissues removed at surgery. In vitro citrate levels in the normal peripheral zone (30.9 +/- 8.5 mumol/g wet weight) and BPH (46.3 +/- 5.4 mumol/g wet weight) were significantly higher than those for prostate cancer (3.74 +/- 0.54 mumol/g wet weight). CONCLUSIONS: These studies further demonstrate the potential of citrate as an in vivo marker for discriminating prostate cancer from surrounding regions of normal peripheral zone and BPH.

Detection of locally recurrent prostate cancer after cryosurgery: evaluation by transrectal ultrasound, magnetic resonance imaging, and three-dimensional proton magnetic resonance spectroscopy.

OBJECTIVES: To assess and compare the clinical usefulness of transrectal ultrasound (TRUS), magnetic resonance imaging (MRI), and three-dimensional proton magnetic resonance spectroscopic imaging (3-D MRSI) in detecting local recurrence of carcinoma of the prostate (CaP) in patients with detectable prostate-specific antigen (PSA) levels after cryosurgery. METHODS: In a prospective study, 25 patients who had undergone cryosurgery as primary treatment for CaP underwent endorectal MRI and 3-D MRSI, followed by TRUS-guided prostate biopsy. At the time of study, 20 patients had detectable PSA; the remaining 5 patients served as controls. All patients had random sextant and guided prostate biopsy for correlation with imaging and MR spectroscopic findings. RESULTS: In patients with detectable PSA, MRSI identified, location-for-location, all foci of CaP and benign prostatic tissue that were detected by prostate biopsy. MRSI identified more sites with CaP than did prostate biopsy, indicating a larger volume of cancer. In 2 patients with detectable PSA and negative prostate biopsy, MRSI identified 11 voxels with viable prostatic tissue. In patients with undetectable PSA, both MRSI and prostate biopsy showed necrosis. Ultrasound and MRI were very poor tools for identifying recurrent cancer and differentiating between viable and necrotic prostate tissue. CONCLUSIONS: 3-D MRSI is superior to TRUS and MRI in differentiating among CaP, BPH, and necrosis when local recurrence after cryosurgery is suspected. By providing chemical mapping of the prostate in contiguous voxels, the addition of spectroscopy to endorectal MRI increases the sensitivity for detection of local recurrence.

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.

Two T2-independent J-difference lactate editing schemes for the PRESS magnetic resonance spectroscopy localization sequence are introduced. The techniques, which allow for simultaneous acquisition of the lactate doublet (1.3 ppm) and edited singlets upfield of and including choline (3.2 ppm), exploit the dependence of the in-phase intensity of the methyl doublet upon the time interval separating two inversion (BASING) pulses applied to its coupling partner after initial excitation. Editing method 1, which allows for echo times TE = n/J (n = 1, 2, 3, . . . . ), alters the BASING carrier frequency for each of two cycles so that, for one cycle, the quartet is inverted, whereas, for the other cycle, the quartet is unaffected. Method 2, which also provides water suppression, allows for editing for TE > 1/J by alternating, between cycles, the time interval separating the inversion pulses. Experimental results were obtained at 1.5 T using a Shinnar Le-Roux-designed maximum phase inversion pulse with a filter transition bandwidth of 55 Hz. Spectra were acquired from phantoms and in vivo from the human brain and neck. In a neck muscle study, the lipid suppression factor, achieved partly through the use of a novel phase regularization algorithm, was measured to be over 10(3). Spectra acquired from a primary brain and a metastatic neck tumor demonstrated the presence of lactate and choline signals consistent with abnormal spectral patterns. The advantages and limitations of the methods are analyzed theoretically and experimentally, and significance of the results is discussed.

Diffusion-weighted MR imaging of acute stroke: correlation with T2-weighted and magnetic susceptibility-enhanced MR imaging in cats.

We evaluated the temporal and anatomic relationships between changes in diffusion-weighted MR image signal intensity, induced by unilateral occlusion of the middle cerebral artery in cats, and tissue perfusion deficits observed in the same animals on T2-weighted MR images after administration of a nonionic intravascular T2 shortening agent. Diffusion-weighted images obtained with strong diffusion-sensitizing gradient strengths (5.6 gauss/cm, corresponding to gradient attenuation factor, b, values of 1413 sec/mm2) displayed increased signal intensity in the ischemic middle cerebral artery territory less than 1 hr after occlusion, whereas T2-weighted images without contrast usually failed to detect injury for 2-3 hr after stroke. After contrast administration (0.5-1.0 mmol/kg by Dy-DTPA-BMA, IV), however, T2-weighted images revealed perfusion deficits (relative hyperintensity) within 1 hr after middle cerebral artery occlusion that corresponded closely to the anatomic regions of ischemic injury shown on diffusion-weighted MR images. Close correlations were also found between early increases in diffusion-weighted MR image signal intensity and disrupted phosphorus-31 and proton metabolite levels evaluated with surface coil MR spectroscopy, as well as with postmortem histopathology. These data indicate that diffusion-weighted MR images more accurately reflect early-onset pathophysiologic changes induced by acute cerebral ischemia than do T2-weighted spin-echo images.

The prostate: MR imaging and spectroscopy. Present and future.

The applications of combined MR imaging and MR spectroscopic imaging of prostate cancer have expanded significantly over the past 10 years and have reached the point of clinical trial results to test robustness and clinical significance. MR spectroscopic imaging extends the diagnostic evaluation of prostate cancer beyond the morphologic information provided by MR imaging throughout the detection of cellular metabolites. The combined metabolic and anatomic information provided by MR imaging and MR spectroscopic imaging has allowed a more accurate assessment of the presence, location, extent, and aggressiveness of prostate cancer both before and after treatment. This information has already demonstrated the ability to improve therapeutic planning for individual prostate cancer patients and shows great promise in the assessment of therapeutic response and the evaluation of new treatment regimes.

Spectroscopy in prostate cancer: hope or hype?

Clinical applications of image-based radiation therapy for the study of prostate cancer have expanded significantly over the past years. The results of recent studies of magnetic resonance imaging (MRI) combined with magnetic resonance spectroscopic imaging (MRSI) demonstrate that the MRI/MRSI exam is a unique method by which to noninvasively study the cellular metabolism and anatomy of the prostate. This technology has the potential to define the tumor volume through functional or metabolic imaging. The results of current MRI/ MRSI studies also provide evidence that the magnitude of metabolic changes in regions of cancer before therapy, as well as the extent of the time course of metabolic changes after therapy, may improve our understanding of cancer aggressiveness. Assessment of cancer spread outside the prostate can be significantly improved by combining MRI findings with estimates of metabolic abnormalities provided by MRSI. Clinically, combined MRI/MRSI has already demonstrated a potential for improved diagnosis, staging, and treatment planning for patients with prostate cancer. Additional studies will reveal both the positive aspects and clinical challenges of MRI/

31P magnetic resonance spectroscopy after combined hyperthermia and radiation.

Mechanisms of uveal melanoma response to therapy are poorly understood. There are a paucity of changes that have been detected immediately after tumor treatment to differentiate successful from ineffective therapy. In this study we used in vivo 31P magnetic resonance spectroscopy (MRS) to assess intra-tumor treatment alterations. The metabolic consequences of effective and ineffective levels of solitary hyperthermia and combined hyperthermia-radiation were investigated. We have previously noted a characteristic 31P MRS pattern with successful hyperthermia in this intraocular melanoma model. The metabolic response after effective or ineffective combined radiation/hyperthermia therapy was indistinguishable from solitary radiation therapy and opposite to that with successful hyperthermia therapy. In contrast to solitary hyperthermia therapy, early changes in 31P spectral ratios following radiation or combined hyperthermia/radiation therapy of uveal melanoma were not predictive of treatment response. Twenty-four to 48 hours after effective or ineffective radiation or combined treatment the Pi/beta-NTP ratio decreased significantly (delta Pi/beta-NTP = -0.433 +/- 0.08 and -0.478 +/- .13 and .10 +/- 0.2, respectively). There was over a 2.0 thermal enhancement of radiation with heat. The increased tumor cell death after combined therapy was reflected by a two-fold larger decrease in beta-NTP signal-to-noise (S/N).

3D MR spectroscopic imaging in the evaluation of prostate cancer.

The management of prostate cancer is a complex issue with a varying range of treatment options available. Magnetic resonance (MR) imaging of the prostate has been available for sometime but has the limitation of only anatomical evaluation. Three-dimensional MR spectroscopy is emerging as a new and sensitive tool in the metabolic evaluation of prostate cancer. This article reviews the principle, techniques, and methods of evaluation of spectroscopy and also discusses the applications of spectroscopy in the current management of prostate cancer.