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Hyperpolarization techniques significantly enhance the sensitivity of magnetic resonance (MR) and thus present fascinating new directions for research and applications with in vivo MR imaging and spectroscopy (MRI/S). Hyperpolarized 13 C MRI/S, in particular, enables real-time non-invasive assessment of metabolic processes and holds great promise for a diverse range of clinical applications spanning fields like oncology, neurology, and cardiology, with a potential for improving early diagnosis of disease, patient stratification, and therapy response assessment. Despite its potential, technical challenges remain for achieving clinical translation. This paper provides an overview of the discussions that took place at the international workshop "New Horizons in Hyperpolarized 13 C MRI," in March 2023 at the Bavarian Academy of Sciences and Humanities, Munich, Germany. The workshop covered new developments, as well as future directions, in topics including polarization techniques (particularly focusing on parahydrogen-based methods), novel probes, considerations related to data acquisition and analysis, and emerging clinical applications in oncology and other fields., (© 2023. The Author(s).)

Purpose To assess the patient-dependent accuracy of atlas-based attenuation correction (ATAC) for brain positron emission tomography (PET) in an integrated time-of-flight (TOF) PET/magnetic resonance (MR) imaging system. Materials and Methods Thirty recruited patients provided informed consent in this institutional review board-approved study. All patients underwent whole-body fluorodeoxyglucose PET/computed tomography (CT) followed by TOF PET/MR imaging. With use of TOF PET data, PET images were reconstructed with four different attenuation correction (AC) methods: PET with patient CT-based AC (CTAC), PET with ATAC (air and bone from an atlas), PET with ATAC patientBone (air and tissue from the atlas with patient bone), and PET with ATAC boneless (air and tissue from the atlas without bone). For quantitative evaluation, PET mean activity concentration values were measured in 14 1-mL volumes of interest (VOIs) distributed throughout the brain and statistical significance was tested with a paired t test. Results The mean overall difference (±standard deviation) of PET with ATAC compared with PET with CTAC was -0.69 kBq/mL ± 0.60 (-4.0% ± 3.2) (P < .001). The results were patient dependent (range, -9.3% to 0.57%) and VOI dependent (range, -5.9 to -2.2). In addition, when bone was not included for AC, the overall difference of PET with ATAC boneless (-9.4% ± 3.7) was significantly worse than that of PET with ATAC (-4.0% ± 3.2) (P < .001). Finally, when patient bone was used for AC instead of atlas bone, the overall difference of PET with ATAC patientBone (-1.5% ± 1.5) improved over that of PET with ATAC (-4.0% ± 3.2) (P < .001). Conclusion ATAC in PET/MR imaging achieves similar quantification accuracy to that from CTAC by means of atlas-based bone compensation. However, patient-specific anatomic differences from the atlas causes bone attenuation differences and misclassified sinuses, which result in patient-dependent performance variation of ATAC. © RSNA, 2017 Online supplemental material is available for this article.

Purpose: Hyperpolarized 13 C MRI is a powerful tool for studying metabolism, but can lack tissue specificity. Gadoxetate is a gadolinium-based MRI contrast agent that is selectively taken into hepatocytes. The goal of this project was to investigate whether gadoxetate can be used to selectively suppress the hyperpolarized signal arising from hepatocytes, which could in future studies be applied to generate specificity for signal from abnormal cell types., Methods: Baseline gadoxetate uptake kinetics were measured using T 1 -weighted contrast enhanced imaging. Relaxivity of gadoxetate was measured for [1- 13 C]pyruvate, [1- 13 C]lactate, and [1- 13 C]alanine. Four healthy rats were imaged with hyperpolarized [1- 13 C]pyruvate using a three-dimensional (3D) MRSI sequence prior to and 15 min following administration of gadoxetate. The lactate:pyruvate ratio and alanine:pyruvate ratios were measured in liver and kidney., Results: Overall, the hyperpolarized signal decreased approximately 60% as a result of pre-injection of gadoxetate. In liver, the lactate:pyruvate and alanine:pyruvate ratios decreased 42% and 78%, respectively (P < 0.05) following gadoxetate administration. In kidneys, these ratios did not change significantly. Relaxivity of gadoxetate for [1- 13 C]alanine was 12.6 times higher than relaxivity of gadoxetate for [1- 13 C]pyruvate, explaining the greater selective relaxation effect on alanine., Conclusions: The liver-specific gadolinium contrast-agent gadoxetate can selectively suppress normal hepatocyte contributions to hyperpolarized 13 C MRI signals. Magn Reson Med 77:2356-2363, 2017. © 2016 International Society for Magnetic Resonance in Medicine., (© 2016 International Society for Magnetic Resonance in Medicine.)

In this work, we present a new ultrafast method for acquiring dynamic 2D EXchange SpectroscopY (EXSY) within a single acquisition. This technique reconstructs two-dimensional EXSY spectra from one-dimensional spectra based on the phase accrual during echo times. The Ultrafast-EXSY acquisition overcomes long acquisition times typically needed to acquire 2D NMR data by utilizing sparsity and phase dependence to dramatically undersample in the indirect time dimension. This allows for the acquisition of the 2D spectrum within a single shot. We have validated this method in simulations and hyperpolarized enzyme assay experiments separating the dehydration of pyruvate and lactate-to-pyruvate conversion. In a renal cell carcinoma cell (RCC) line, bidirectional exchange was observed. This new technique revealed decreased conversion of lactate-to-pyruvate with high expression of monocarboxylate transporter 4 (MCT4), known to correlate with aggressive cancer phenotypes. We also showed feasibility of this technique in vivo in a RCC model where bidirectional exchange was observed for pyruvate-lactate, pyruvate-alanine, and pyruvate-hydrate and were resolved in time. Broadly, the technique is well suited to investigate the dynamics of multiple exchange pathways and applicable to hyperpolarized substrates where chemical exchange has shown great promise across a range of disciplines., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Radiofrequency (RF) field (B 1) inhomogeneity due to shortened wavelength at high field is a major cause of magnetic resonance imaging (MRI) nonuniformity in high dielectric biological samples (e.g., human body). In this work, we propose a method to improve the B 1 and MRI homogeneity by using pre-emphasized non-uniform B 1 distribution. The intrinsic B 1 distribution that could be generated by a RF volume coil, specifically a microstrip transmission line (MTL) coil used in this work, was pre-emphasized in the sample's periphery region of interest to compensate for the central brightness induced by high frequency interference effect due to shortened wave length. This pre-emphasized non-uniform B 1 can be realized by varying the parameters of microstrip elements, such as the substrate thickness of MTL volume coil. Both numerical simulation and phantom MR imaging studies were carried out to investigate the feasibility and merit of the proposed method in achieving homogeneous MR images. The simulation results demonstrate that by using a pre-emphasized B 1 distribution generated by the MTL volume coil, relatively uniform B 1 distribution and homogeneous MR image (98% homogeneity) within the spherical phantom (15 cm diameter) were achieved with 4.5 mm thickness. The B 1 and MRI intensity distributions of a 16-element MTL volume coil with fixed substrate thickness and five varied saline loads were modeled and experimentally tested. Similar results from both simulation and experiments were obtained, suggesting substantial improvements of B 1 and MRI homogeneities within the phantom containing 125 mM saline. The overall results demonstrate an efficient B 1 shimming approach for improving high field MRI.

In a multimodal volume coil, only one mode can generate homogeneous Radiofrequency (RF) field for Magnetic Resonance Imaging. The existence of other modes may increase the volume coil design difficulties and potentially decreases coil performance. In this study, we introduce common-mode resonator technique to high and ultrahigh field volume coil designs to reduce the resonant mode while maintain the homogeneity of the RF field. To investigate the design method, the common-mode resonator was realized by using a microstrip line which was split along the central to become a pair of parallel transmission lines within which common-mode currents exist. Eight common-mode resonators were placed equidistantly along the circumference of a low loss dielectric cylinder to form a volume coil. Theoretical analysis and comparison between the 16-strut common-mode volume coil and a conventional 16-strut volume coil in terms of RF field homogeneity and efficiency was performed using Finite-Difference Time-Domain (FDTD) method at 298.2 MHz. MR imaging experiments were performed by using a prototype of the common-mode volume coil on a whole body 7 Tesla scanner. FDTD simulation results showed the reduced number of resonant modes of the common-mode volume coil over the conventional volume coil, while the RF field homogeneity of the two type volume coils was kept at the same level. MR imaging of a water phantom and a kiwi fruit showing the feasibility of the proposed method for simplifying the volume coil design is also presented.

Purpose: Parallel magnetic resonance imaging (MRI) requires an array of RF coil elements with different sensitivity distributions and with minimal electromagnetic coupling. The goal of this project was to develop a new method based on induced current compensation or elimination (ICE) for improved coil element decoupling and to investigate its performance in phantom MR images., Methods: An electromagnetic decoupling method based on induced current compensation or elimination for nonoverlapping RF coil arrays was developed with the design criteria of high efficiency, easy implementation, and no physical connection to RF array elements. An eigenvalue/eigenvector approach was employed to analyze the decoupling mechanism and condition. A two-channel microstrip array and an eight-channel coil array were built to test the performance of the method. Following workbench tests, MR imaging experiments were performed on a 7T MR scanner., Results: The bench tests showed that both arrays achieved sufficient decoupling with a S21 less than -25 dB among the coil elements at 298 MHz. The MR phantom images demonstrated well-defined sensitivity distributions from each coil element and the unique decoupling capability of the proposed ICE decoupling technique. B1 distributions of the individual elements were also measured and calculated., Conclusions: The theoretical analysis and experiments demonstrated the feasibility of the decoupling method for high field RF coil array designs without overlapping or direct physical connections between coil elements, which provide more flexibility for coil array design and optimization. The method offers a new approach to address the RF array decoupling issue, which is a major challenge in implementing parallel imaging.

Purpose: This study presents the steps and criteria involved in the series of image registrations used clinically during the planning and dose delivery of focal high dose-rate (HDR) brachytherapy of the prostate., Material and Methods: Three imaging modalities - Magnetic Resonance Imaging (MRI), Magnetic Resonance Spectroscopic Imaging (MRSI), and Computed Tomography (CT) - were used at different steps during the process. MRSI is used for identification of dominant intraprosatic lesions (DIL). A series of rigid and nonrigid transformations were applied to the data to correct for endorectal-coil-induced deformations and for alignment with the planning CT. Mutual information was calculated as a morphing metric. An inverse planning optimization algorithm was applied to boost dose to the DIL while providing protection to the urethra, penile bulb, rectum, and bladder. Six prostate cancer patients were treated using this protocol., Results: The morphing algorithm successfully modeled the probe-induced prostatic distortion. Mutual information calculated between the morphed images and images acquired without the endorectal probe showed a significant ( p = 0.0071) increase to that calculated between the unmorphed images and images acquired without the endorectal probe. Both mutual information and visual inspection serve as effective diagnostics of image morphing. The entire procedure adds less than thirty minutes to the treatment planning., Conclusion: This work demonstrates the utility of image transformations and registrations to HDR brachytherapy of prostate cancer.

We report metabolic images of (13)C, following injection of a bolus of hyperpolarized [1-(13)C] pyruvate in a live rat. The data were acquired on a clinical scanner, using custom coils for volume transmission and array reception. Proton blocking of all carbon resonators enabled proton anatomic imaging with the system body coil, to allow for registration of anatomic and metabolic images, for which good correlation was achieved, with some anatomic features (kidney and heart) clearly visible in a carbon image, without reference to the corresponding proton image. Parallel imaging with sensitivity encoding was used to increase the spatial resolution in the SI direction of the rat. The signal to noise ratio in was in some instances unexpectedly high in the parallel images; variability of the polarization among different trials, plus partial volume effects, are noted as a possible cause of this., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Fetal MRI on 1.5T clinical scanner has been increasingly becoming a powerful imaging tool for studying fetal brain abnormalities in vivo. Due to limited availability of dedicated fetal phased arrays, commercial torso or cardiac phased arrays are routinely used for fetal scans, which are unable to provide optimized SNR and parallel imaging performance with a small number coil elements, and insufficient coverage and filling factor. This poses a demand for the investigation and development of dedicated and efficient radiofrequency (RF) hardware to improve fetal imaging. In this work, an investigational approach to simulate the performance of multichannel flexible phased arrays is proposed to find a better solution to fetal MR imaging. A 32 channel fetal array is presented to increase coil sensitivity, coverage and parallel imaging performance. The electromagnetic field distribution of each element of the fetal array is numerically simulated by using finite-difference time-domain (FDTD) method. The array performance, including B(1) coverage, parallel reconstructed images and artifact power, is then theoretically calculated and compared with the torso array. Study results show that the proposed array is capable of increasing B(1) field strength as well as sensitivity homogeneity in the entire area of uterus. This would ensure high quality imaging regardless of the location of the fetus in the uterus. In addition, the paralleling imaging performance of the proposed fetal array is validated by using artifact power comparison with torso array. These results demonstrate the feasibility of the 32 channel flexible array for fetal MR imaging at 1.5T.

Formulation, polarization, and dissolution conditions were developed to obtain a stable hyperpolarized solution of [1-(13)C]-ethyl pyruvate. A maximum tolerated concentration and injection rate were determined, and (13)C spectroscopic imaging was used to compare the uptake of hyperpolarized [1-(13)C]-ethyl pyruvate relative to hyperpolarized [1-(13)C]-pyruvate into anesthetized rat brain. Hyperpolarized [1-(13)C]-ethyl pyruvate and [1-(13)C]-pyruvate metabolic imaging in normal brain is demonstrated and quantified in this feasibility and range-finding study., ((c) 2010 Wiley-Liss, Inc.)

Magnetic resonance imaging has been widely used noninvasively for pediatric neuroimaging for more than a decade. More recently, with advances in computing, functional techniques for imaging water diffusion, cellular metabolite levels, and blood flow are becoming available. Magnetic resonance spectroscopy imaging (MRSI) offers a snapshot of the metabolic status in the tissue of interest. It is complementary to the more traditionally used anatomic imaging for diagnoses of various abnormalities. This review describes the physical basis of proton MRSI, summarizes currently available techniques and their applications, highlights challenges of performing MRSI in the pediatric population, and previews the newest techniques currently on the horizon., ((c) 2010 Elsevier Inc. All rights reserved.)

Objective: Magnetic resonance imaging at 7 Tesla produces high-resolution gradient-echo phase images of patients with multiple sclerosis (MS) that quantify the local field shifts from iron in the basal ganglia and lesions. Phase imaging is easily integrated into clinical examinations because it is a postprocessing technique and does not require additional scanning. The purpose of this study was to quantify local field shifts in MS and to investigate their relation to disease duration and disability status., Methods: Thirty-two subjects including 19 patients with MS and 13 age- and sex-matched control subjects were scanned at a spatial resolution of up to 195 x 260 microm. Data were postprocessed to produce anatomical quantitative phase images of local field shifts, as well as conventional magnitude images., Results: The phase images showed an increased local field in the caudate, putamen, and globus pallidus of patients relative to control subjects (p < 0.01). The local field in the caudate was strongly correlated with disease duration (r(2) = 0.77; p < 0.001). Phase images showed contrast in 74% of the 403 lesions, increasing the total lesion count by more than 30% and showing distinct peripheral rings and a close association with vasculature., Interpretation: The increased field in the basal ganglia and correlation with disease duration suggest pathological iron content increases in MS. The peripheral phase rings are consistent with histological data demonstrating iron-rich macrophages at the periphery of a subset of lesions. The clearly defined vessels penetrating MS lesions should increase our ability to detect focal vascular abnormalities specifically related to demyelinating processes.

This paper describes and compares novel approaches to in vivo 3D measurement of brain surface folding in clinically acquired neonatal MR image data, which allows regional folding evaluation. Most of the current measures of folding are not independent of the area of the surface they are derived from. Therefore, applying them to whole-brain surfaces or subregions of different sizes results in differences which may or may not reflect true differences in folding. We address this problem by proposing new measures to quantify gyrification and two approaches to normalize previously defined measures. The method was applied to twelve premature infants (age 28-37 weeks) from which cerebrospinal fluid/gray matter and gray matter/white matter interface surfaces were extracted. Experimental results show that previous folding measures are sensitive to the area of the surface of analysis and that the area-independent measures proposed here provide significant improvements. Such a system provides a tool that facilitates the study of structural development in the neonatal brain within specific functional subregions, which may be critical in identifying later neurological impairment.

Purpose of Review: The purpose of this article is to review the current status of advanced MRI techniques based on anatomic, metabolic and physiologic properties of prostate cancer with a focus on their impact in managing prostate cancer patients., Recent Findings: Prostate cancer can be identified based on reduced T2 signal intensity on MRI, increased choline and decreased citrate and polyamines on magnetic resonance spectroscopic imaging (MRSI), decreased diffusivity on diffusion tensor imaging (DTI), and increased uptake on dynamic contrast enhanced (DCE) imaging. All can be obtained within a 60-min 3T magnetic resonance exam. Each complementary method has inherent advantages and disadvantages: T2 MRI has high sensitivity but poor specificity; magnetic resonance spectroscopic imaging has high specificity but poor sensitivity; diffusion tensor imaging has high spatial resolution, is the fastest, but sensitivity/specificity needs to be established; dynamic contrast enhanced imaging has high spatial resolution, but requires a gadolinium based contrast agent injection, and sensitivity/specificity needs to be established., Summary: The best characterization of prostate cancer in individual patients will most likely result from a multiparametric (MRI/MRSI/DTI/DCE) exam using 3T magnetic resonance scanners but questions remain as to how to analyze and display this large amount of imaging data, and how to optimally combine the data for the most accurate assessment of prostate cancer. Histological correlations or clinical outcomes are required to determine sensitivity/specificity for each method and optimal combinations of these approaches.

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.

The purpose of this work was to investigated the feasibility of fully-balanced steady-state free-precession (bSSFP) pulse sequence for trabecular bone and knee cartilage imaging in vivo using ultra-high-field (UHF) MRI at 7T in comparison with pulse sequences previously used at 3T. We showed that bSSFP and spin-echo imaging is possible at higher field strengths within 3.2 W/kg specific absorption rate (SAR) constraints. All pulse sequences were numerically optimized based on measured tissue relaxation parameters from six healthy volunteers (T(1) = 820 +/- 128 ms, T(2) = 43.5 +/- 3 ms for bone marrow and T(1) = 1745 +/- 104 ms and T(2) = 30 +/- 4 ms for cartilage). From simulations of the Bloch equation, a signal-to-noise ratio (SNR) increase of more than 1.9 was predicted. Cartilage SNR of bSSFP was 2.4 times higher at 7T (51.3 +/- 4.3) compared with 3T (21.3 +/- 3.3). Bone SNR increased from 11.8 +/- 2.0 to 13.2 +/- 2.5 at the higher field strength. We concluded that there is SNR benefit and great potential for bone and cartilage imaging at higher field strength., ((c) 2007 Wiley-Liss, Inc.)

Glutamate and glutamine are important neurochemicals in the central nervous system and the neurotoxic properties of excess glutamate have been associated with several neurodegenerative diseases. The TE-Averaged PRESS technique has been shown by our group to detect an unobstructed glutamate signal at 3 T that is resolved from glutamine and NAA at 2.35 ppm. TE-Averaged PRESS therefore provides an unambiguous measurement of glutamate as well as other metabolites such as NAA, choline, creatine, and myo-inositol. In this study, we extend the single voxel TE-Averaged PRESS technique for two-dimensional (2D) spectroscopic imaging (TE-Averaged MRSI) to generate 2D glutamate maps. To facilitate TE-Averaged MRSI within a reasonable time, a fast encoding trajectory was used. This enabled rapid acquisition of TE-Averaged spectral arrays with good spectral bandwidth (977 Hz) and resolution (approximately 2 Hz). MRSI data arrays of 10 x 16 were acquired with 1.8 cm3 spatial resolution over a approximately 110 cm3 volume in a scan time of approximately 21 min. Two-dimensional metabolite maps were obtained with good SNR and clear differentiation in glutamate levels was observed between gray and white matter with significantly higher glutamate in gray matter relative to white matter as anticipated.

This paper describes a novel approach to in-vivo measurement of brain surface folding in clinically acquired neonatal MR image data, which allows evaluation of surface curvature within subregions of the cortex. This paper addresses two aspects of this problem. Firstly: normalization of folding measures to provide area-independent evaluation of surface folding over arbitrary subregions of the cortex. Secondly: automated parcellation of the cortex at a particular developmental stage, based on an approximate spatial normalization of previously developed anatomical boundaries. The method was applied to seven premature infants (age 28-37 weeks) from which gray matter and gray-white matter interface surfaces were extracted. Experimental results show that previous folding measures are sensitive to the size of the surface of analysis, and that the area independent measures proposed here provide significant improvements. Such a system provides a tool to allow the study of structural development in the neonatal brain within specific functional subregions, which may be critical in identifying later neurological impairment.

This paper describes a novel approach to forming high resolution MR images of the human fetal brain. It addresses the key problem of motion of the fetus by proposing a registration refined compounding of multiple sets of orthogonal fast 2D MRI slices, that are currently acquired for clinical studies, into a single high resolution MRI volume. A robust multi-resolution slice alignment is applied iteratively to the data to correct motion of the fetus that occurs between 2D acquisitions. This is combined with an intensity correction step and a super resolution reconstruction step, to form a single high isotropic resolution volume of the fetal brain. Experimental validation on synthetic image data with known motion types and underlying anatomy, together with retrospective application to sets of clinical acquisitions are included. Results indicate the method promises a unique route to acquiring high resolution MRI of the fetal brain in vivo allowing comparable quality to that of neonatal MRI. Such data is highly valuable in allowing a clinically applicable window into the process of normal and abnormal brain development.

Objective: Our aim was to determine whether parallel imaging and diffusion tensor imaging affect the measurement of apparent diffusion coefficient (ADC) during diffusion-weighted MRI of the liver in healthy volunteers., Subjects and Methods: We performed breath-hold single-shot echo-planar diffusion-weighted MRI of the liver in 10 healthy volunteers using conventional diffusion, conventional diffusion with parallel imaging, and diffusion tensor with parallel imaging sequences. TE values for the three sequences were 83, 74, and 63, respectively. Liver signal intensity was measured on all sequences and normalized to the SD of the measurement. Hepatic ADC was calculated by acquiring all sequences with b values of 0 and 500 sec/mm(2)., Results: The normalized liver signal intensity was higher on diffusion tensor with parallel imaging and conventional diffusion with parallel imaging than on conventional diffusion without parallel imaging for a b value of 500 sec/mm(2) (13.0 and 10.1 vs 9.1, respectively; p < 0.03) and for a b value of 0 sec/mm(2) (9.0 and 7.6 vs 6.9, respectively; without reaching a significant difference, p = 0.12). Hepatic ADC was not significantly different between sequences (p = 0.16)., Conclusion: Higher signal intensity can be obtained when using parallel imaging and diffusion tensor imaging during diffusion-weighted MRI of the liver without compromising hepatic ADC measurement.

Myo-inositol is a strongly coupled system and resonates at four chemical shift positions. At 1.5 T, only the singlet component at 3.57 ppm is detected. However, at 3 T this resonance is resolved into its components at 3.55 ppm and 3.61 ppm. Due to the increased spectral resolution and signal-to-noise ratio, it is anticipated that the quantification of myo-inositol should improve at 3 T. Using data from normal controls and the LCmodel quantification procedure, we found that the quantification precision, reproducibility and detection sensitivity of myo-inositol is significantly better at 3 T relative to 1.5 T.

The goal of this study was to determine whether presurgical metabolite levels measured by 3D MR Spectroscopic Imaging (MRSI) can accurately detect viable cancer within human brain tumor masses. A total of 31 patients (33 exams, 39 pathology correlations) with brain tumors were studied prior to surgical biopsy and/or resection. The 3D MRSI was obtained with a spatial resolution of 0.2 to 1 cc throughout the majority of the mass and adjacent brain tissue using PRESS-CSI localization. Levels of choline, creatine and NAA were estimated from the locations of the resected tissue and normalized to normal appearing brain tissue. The data were correlated with subsequent histologic analysis of the biopsy tissue samples. Although there were large variations in the metabolite ratios, all regions of confirmed cancer demonstrated significant choline levels and a mean choline/NAA ratio of 5.84 + 2.58 with the lowest value being 1.3. This lowest value is greater than 4 standard deviations above the mean (0.52 +/- 0.13) found in 8 normal volunteers. The choline signal intensities in confirmed cancers were significantly elevated compared to normal appearing brain tissue with a mean ratio of 1.71 +/- 0.69. Spectra with no significant metabolite levels were observed in the non-enhancing necrotic core of the tumor masses. The results of this study indicate that 3D MRSI of brain tumors can detect abnormal metabolite levels in regions of viable cancer and grades and can differentiate cancer from necrosis and/or normal brain tissue.

Background and Purpose: Neurologic and developmental outcomes of asphyxiated, term neonates are difficult to predict applying clinical or laboratory criteria. In this study, we investigated the association of MR spectroscopy (MRS) results with neurodevelopmental status at age 12 months., Method: Thirty-one term neonates, who were enrolled in a prospective study of the utility of MR imaging for the determination of neurologic and developmental status, underwent single-voxel proton MRS of the basal nuclei and intervascular boundary zones. Ratios of lactate, choline, creatine, and N-acetylaspartate (NAA) peaks were calculated and tested for association with neuromotor scores and Mental Development Index of the Bayley Scores of Infant Development obtained at age 12 months., Results: Elevated lactate and diminished NAA were the most common findings in infants with neurologic and developmental abnormalities at age 12 months. Although many ratios had statistically significant associations with outcome (P<.05), the highest significance was obtained with lactate/choline ratios in the basal nuclei. A false-positive finding was seen in a patient who was born after a 36-week gestation period (high lactate/choline but normal neurodevelopmental status at 12 months) and in three patients with apparent watershed injury (high watershed lactate/choline but normal neurodevelopmental status at 12 months). A false-negative MRS finding (normal lactate/choline but abnormal outcome) was seen in a patient who had an apparent prenatal injury., Conclusion: Proton MRS appears to be a useful tool for assessing brain injury in neonates who have suffered hypoxia or ischemia. Correlation with gestational age and imaging findings are essential for proper interpretation of the spectra. Patients with apparent watershed injuries may have normal neurodevelopmental status at age 12 months.

Purpose: We developed a scoring system for the assessment of perinatal asphyxia as depicted on MR images., Methods: Four scoring systems were derived to evaluate MR images obtained in asphyxiated neonates: the basal ganglia (BG) score, the watershed (W) score, the combined basal ganglia/watershed (BG/W) score, and the sum of the BG and W scores, the summation (S) score. In addition, three MR sequences, T1-weighted, first-echo T2-weighted, and second-echo T2-weighted, were assessed for each patient for each scoring system. Neuromotor examinations were performed at ages 3 and 12 months, and cognitive development was tested at age 12 months. Statistical analysis was then performed to test the relationship between the MR scores and the outcome scores., Results: The BG/W score, obtained with the first-echo T2-weighted sequence, was the most useful overall score for predicting neuromotor outcome at 3 and 12 months and cognitive outcome at 12 months. T1-weighted and first-echo T2-weighted sequences showed a stronger association with outcome in patients imaged during the first postnatal week, whereas second-echo T2-weighted sequences showed a stronger association with outcome in patients imaged during the second postnatal week., Conclusion: It appears that, with the use of the BG/W score, MR imaging discriminates accurately between patients with good and poor neuromotor and cognitive outcome at 3 and 12 months. In terms of our scoring systems, the first-echo T2-weighted sequence appears to discriminate best between patients with good and poor 3- and 12-month outcomes. Proper use of the imaging sequences and scoring systems described in this article can increase the knowledge base upon which treatment decisions are made in asphyxiated neonates.

Purpose: To compare the performance of pelvic phased-array (PPA) coils and integrated endorectal PPA coils in evaluation of local extent of prostate cancer., Materials and Methods: Seventy-one men underwent magnetic resonance (MR) imaging within 3 weeks of radical prostatectomy. MR findings of tumor, extracapsular extension, seminal vesicle invasion, nodal involvement, and stage were compared with step-sectioned (3-4-mm intervals) whole-mounted pathologic specimens. Prospective consensus versus single-reader interpretation (kappa statistics) and PPA versus integrated endorectal PPA coils (McNemar test) were compared, and a rating scale of 1-6 was developed for analysis of receiver operating characteristics. Statistical significance was calculated at delta = .05., Results: Comparison between consensus and single-reader image interpretation showed positive but poor agreement (kappa = .38) and no statistical significance. Staging accuracy was better (difference approached significance) for integrated endorectal PPA coils (77%) than for PPA coils (68%)., Conclusion: The integrated endorectal PPA coil is better for evaluation of local prostatic cancer than is the PPA coil.

Proton-decoupled, 31P three-dimensional (3-D) chemical shift imaging (CSI) spectra have been acquired from the entire human brain using a new dual tuned resonator. The resonator operates in quadrature mode to provide improved sensitivity, excellent B1 homogeneity and reduced power deposition at both frequencies. Proton-decoupled and fully NOE enhanced, 31P spectra were acquired from normal volunteers using Waltz-4 proton decoupling with continuous wave bi-level excitation applied through a second radio frequency channel. Well resolved peaks in the phosphomonoester (PME) and phosphodiester regions were obtained from nonlocalized FIDs and spectra localized with 3-D CSI without processing for resolution enhancement. pH measurements made over large regions of the brain using the P(i) resonance show no significant variations (6.9 +/- 0.02) for a single individual. The improved spectral resolution and sensitivity of the PME resonances results in more well defined metabolite images of the PME peak region.