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Reprogramming of energy metabolism in the development of prostate cancer can be exploited for a better diagnosis and treatment of the disease. The goal of this study was to determine whether differences in glucose and pyruvate metabolism of human prostate cancer cells with dissimilar aggressivenesses can be detected using hyperpolarized [1‐13C]pyruvate MRS and [18F]FDG‐PET imaging, and to evaluate whether these measures correlate. For this purpose, we compared murine xenografts of human prostate cancer LNCaP cells with those of more aggressive PC3 cells. [1‐13C]pyruvate was hyperpolarized by dissolution dynamic nuclear polarization (dDNP) and [1‐13C]pyruvate to lactate conversion was followed by 13C MRS. Subsequently [18F]FDG uptake was investigated by static and dynamic PET measurements. Standard uptake values (SUVs) for [18F]FDG were significantly higher for xenografts of PC3 compared with those of LNCaP. However, we did not observe a difference in the average apparent rate constant kpl of 13C label exchange from pyruvate to lactate between the tumor variants. A significant negative correlation was found between SUVs from [18F]FDG PET measurements and kpl values for the xenografts of both tumor types. The kpl rate constant may be influenced by various factors, and studies with a range of prostate cancer cells in suspension suggest that LDH inhibition by pyruvate may be one of these. Our results indicate that glucose and pyruvate metabolism in the prostate cancer cell models differs from that in other tumor models and that [18F]FDG‐PET can serve as a valuable complementary tool in dDNP studies of aggressive prostate cancer with [1‐13C]pyruvate. [ABSTRACT FROM AUTHOR]

Purpose: To determine the changes in prostate shape and volume after the introduction of an endorectal coil (ERC) by means of magnetic resonance imaging (MRI) at 3T. Methods and materials: A total of 44 consecutive patients with biopsy-proven prostate cancer underwent separate MRI examinations at 3T with a body array coil and subsequently with an ERC inflated with 50 mL of fluid. Prospectively, two experienced readers independently evaluated all data sets in random order. The maximal anteroposterior, right-to-left, and craniocaudal prostate diameters, as well as the total prostate and peripheral zone and central gland volumes were measured before and after ERC introduction. The changes in prostate shape and volume were analyzed using Wilcoxon''s test for paired samples. Results: The introduction of the ERC significantly changed the prostate shape in all three directions, with mean changes in the anteroposterior, right-to-left, and craniocaudal diameters of 15.7% (5.5 mm), 7.7% (3.5 mm), and 6.3% (2.2 mm), respectively. The mean total prostate, peripheral zone, and central gland volume decreased significantly after ERC introduction by 17.9% (8.3 cm3), 21.6% (4.8 cm3), and 14.2% (3.4 cm3), respectively. Conclusion: ERC introduction as observed by 3T MRI changed the prostate shape and volume significantly. The mean anteroposterior diameter was reduced by nearly one-sixth of its original diameter, and the mean total prostate volume was decreased by approximately 18%. This could cause difficulties and should be considered when using ERC-based MRI for MRI-computed tomography fusion and radiotherapy planning. [Copyright &y& Elsevier]

Proton magnetic resonance spectroscopic imaging ( 1 H MRSI) enables non-invasive assessment of certain metabolites in the prostate gland. Several studies have demonstrated that this metabolic information, in combination with anatomical information from T2-weighted MR imaging significantly improves prostate cancer detection, localization and disease characterization. The technology of 1 H MRSI is continuously evolving with improvements of hardware and acquisition methods. Recently, 31 P and 13 C MRSI of the prostate have regained new interest after a dormant period of decades. This review focuses on recent technical progress of in vivo 1 H MRSI of the prostate, in particular those that enhance clinical applicability at 3T with respect to commonly used techniques to examine the prostate. These developments consist of higher magnetic field strengths, and better MR coils and acquisition techniques. Besides the improvements for 1 H MRSI, the developments and opportunities for 31 P and 13 C MRSI for the prostate are reviewed. Finally, we briefly review 13 C MRS of the prostate, in particular the new possibilities with hyperpolarized substrates. [ABSTRACT FROM AUTHOR]

Abstract: Background: A challenge in the diagnosis of prostate cancer (PCa) is the accurate assessment of aggressiveness. Objective: To validate the performance of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) of the prostate at 3 tesla (T) for the assessment of PCa aggressiveness, with prostatectomy specimens as the reference standard. Design, settings, and participants: A total of 45 patients with PCa scheduled for prostatectomy were included. This study was approved by the institutional review board; the need for informed consent was waived. Outcome measurements and statistical analysis: Subjects underwent a clinical MRI protocol including DCE-MRI. Blinded to DCE-images, PCa was indicated on T2-weighted images based on histopathology results from prostatectomy specimens with the use of anatomical landmarks for the precise localization of the tumor. PCa was classified as low-, intermediate-, or high-grade, according to Gleason score. DCE-images were used as an overlay on T2-weighted images; mean and quartile values from semi-quantitative and pharmacokinetic model parameters were extracted per tumor region. Statistical analysis included Spearman's ρ, the Kruskal-Wallis test, and a receiver operating characteristics (ROC) analysis. Results and limitations: Significant differences were seen for the mean and 75th percentile (p75) values of wash-in (p = 0.024 and p = 0.017, respectively), mean wash-out (p = 0.044), and p75 of transfer constant (K trans) (p = 0.035), all between low-grade and high-grade PCa in the peripheral zone. ROC analysis revealed the best discriminating performance between low-grade versus intermediate-grade plus high-grade PCa in the peripheral zone for p75 of wash-in, K trans, and rate constant (K ep) (area under the curve: 0.72). Due to a limited number of tumors in the transition zone, a definitive conclusion for this region of the prostate could not be drawn. Conclusions: Quantitative parameters (K trans and K ep) and semi-quantitative parameters (wash-in and wash-out) derived from DCE-MRI at 3 T have the potential to assess the aggressiveness of PCa in the peripheral zone. P75 of wash-in, K trans, and K ep offer the best possibility to discriminate low-grade from intermediate-grade plus high-grade PCa. [Copyright &y& Elsevier]

Abstract: Background: One of the most important clinical challenges in prostate cancer (PCa) management is an in vivo assessment of cancer aggressiveness. Objective: To validate the performance of magnetic resonance (MR) spectroscopic imaging (MRSI) of the prostate at 3 T for the purpose of assessing tumour aggressiveness based on the ratio of choline plus creatine to citrate (Cho+Cr/Cit) and of choline to creatine (Cho/Cr), using the Gleason score of the radical prostatectomy (RP) specimen as the gold standard. Design, setting, and participants: A total of 43 biopsy-proven PCa patients with 53 clinically relevant tumour foci were retrospectively included in this study. Measurements: Patients underwent MR imaging and MRSI examination followed by RP. From MRSI, all spectroscopy voxels containing tumour were selected by a radiologist guided by the prostatectomy histopathology map only. For each tumour, two spectroscopists determined the maximum Cho+Cr/Cit, Cho/Cr, and malignancy rating using a standardised threshold approach, incorporating both metabolic ratios. The maximum Cho+Cr/Cit, Cho/Cr, and malignancy ratings showed a relation to tumour aggressiveness and so were used to differentiate among tumour aggressiveness classes. Results and limitations: The maximum Cho+Cr/Cit ratio, maximum Cho/Cr ratio, and malignancy rating of a standardised threshold approach separated low-grade from higher-grade tumours, with areas under the receiver operating characteristic (ROC) curves of 0.70, 0.74, and 0.78, respectively. Conclusions: MRSI offers possibilities for an in vivo, noninvasive assessment of PCa aggressiveness. The combination of the different metabolite ratios was used with promising results for discrimination among different aggressiveness classes. [Copyright &y& Elsevier]

Purpose: To demonstrate the theoretical feasibility of integrating two functional prostate magnetic resonance imaging (MRI) techniques (dynamic contrast-enhanced MRI [DCE-MRI] and 1H-spectroscopic MRI [MRSI]) into inverse treatment planning for definition and potential irradiation of a dominant intraprostatic lesion (DIL) as a biologic target volume for high-dose intraprostatic boosting with intensity-modulated radiotherapy (IMRT). Methods and Materials: In 5 patients, four gold markers were implanted. An endorectal balloon was inserted for both CT and MRI. A DIL volume was defined by DCE-MRI and MRSI using different prostate cancer-specific physiologic (DCE-MRI) and metabolic (MRSI) parameters. CT-MRI registration was performed automatically by matching three-dimensional gold marker surface models with the iterative closest point method. DIL-IMRT plans, consisting of whole prostate irradiation to 70 Gy and a DIL boost to 90 Gy, and standard IMRT plans, in which the whole prostate was irradiated to 78 Gy were generated. The tumor control probability and rectal wall normal tissue complication probability were calculated and compared between the two IMRT approaches. Results: Combined DCE-MRI and MRSI yielded a clearly defined single DIL volume (range, 1.1-6.5 cm3) in all patients. In this small, selected patient population, no differences in tumor control probability were found. A decrease in the rectal wall normal tissue complication probability was observed in favor of the DIL-IMRT plan versus the plan with IMRT to 78 Gy. Conclusion: Combined DCE-MRI and MRSI functional image-guided high-dose intraprostatic DIL-IMRT planned as a boost to 90 Gy is theoretically feasible. The preliminary results have indicated that DIL-IMRT may improve the therapeutic ratio by decreasing the normal tissue complication probability with an unchanged tumor control probability. A larger patient population, with more variations in the number, size, and localization of the DIL, and a feasible mechanism for treatment implementation has to be studied to extend these preliminary tumor control and toxicity estimates. [ABSTRACT FROM AUTHOR]