The success of cellular therapies will depend in part on accurate delivery of cells to target organs. In dendritic cell therapy, in particular, delivery and subsequent migration of cells to regional lymph nodes is essential for effective stimulation of the immune system. We show here that in vivo magnetic resonance tracking of magnetically labeled cells is feasible in humans for detecting very low numbers of dendritic cells in conjunction with detailed anatomical information. Autologous dendritic cells were labeled with a clinical superparamagnetic iron oxide formulation or (111)In-oxine and were co-injected intranodally in melanoma patients under ultrasound guidance. In contrast to scintigraphic imaging, magnetic resonance imaging (MRI) allowed assessment of the accuracy of dendritic cell delivery and of inter- and intra-nodal cell migration patterns. MRI cell tracking using iron oxides appears clinically safe and well suited to monitor cellular therapy in humans.

This review presents the current state of the art regarding multiparametric magnetic resonance (MR) imaging of prostate cancer. Technical requirements and clinical indications for the use of multiparametric MR imaging in detection, localization, characterization, staging, biopsy guidance, and active surveillance of prostate cancer are discussed. Although reported accuracies of the separate and combined multiparametric MR imaging techniques vary for diverse clinical prostate cancer indications, multiparametric MR imaging of the prostate has shown promising results and may be of additional value in prostate cancer localization and local staging. Consensus on which technical approaches (field strengths, sequences, use of an endorectal coil) and combination of multiparametric MR imaging techniques should be used for specific clinical indications remains a challenge. Because guidelines are currently lacking, suggestions for a general minimal protocol for multiparametric MR imaging of the prostate based on the literature and the authors' experience are presented. Computer programs that allow evaluation of the various components of a multiparametric MR imaging examination in one view should be developed. In this way, an integrated interpretation of anatomic and functional MR imaging techniques in a multiparametric MR imaging examination is possible. Education and experience of specialist radiologists are essential for correct interpretation of multiparametric prostate MR imaging findings. Supportive techniques, such as computer-aided diagnosis are needed to obtain a fast, cost-effective, easy, and more reproducible prostate cancer diagnosis out of more and more complex multiparametric MR imaging data.

Proton MRS (1H MRS) provides noninvasive, quantitative metabolite profiles of tissue and has been shown to aid the clinical management of several brain diseases. Although most modern clinical MR scanners support MRS capabilities, routine use is largely restricted to specialized centers with good access to MR research support. Widespread adoption has been slow for several reasons, and technical challenges toward obtaining reliable good‐quality results have been identified as a contributing factor. Considerable progress has been made by the research community to address many of these challenges, and in this paper a consensus is presented on deficiencies in widely available MRS methodology and validated improvements that are currently in routine use at several clinical research institutions. In particular, the localization error for the PRESS localization sequence was found to be unacceptably high at 3 T, and use of the semi‐adiabatic localization by adiabatic selective refocusing sequence is a recommended solution. Incorporation of simulated metabolite basis sets into analysis routines is recommended for reliably capturing the full spectral detail available from short TE acquisitions. In addition, the importance of achieving a highly homogenous static magnetic field (B0) in the acquisition region is emphasized, and the limitations of current methods and hardware are discussed. Most recommendations require only software improvements, greatly enhancing the capabilities of clinical MRS on existing hardware. Implementation of these recommendations should strengthen current clinical applications and advance progress toward developing and validating new MRS biomarkers for clinical use.

A large body of published work shows that proton (hydrogen 1 [ 1 H]) magnetic resonance (MR) spectroscopy has evolved from a research tool into a clinical neuroimaging modality. Herein, the authors present a summary of brain disorders in which MR spectroscopy has an impact on patient management, together with a critical consideration of common data acquisition and processing procedures. The article documents the impact of 1 H MR spectroscopy in the clinical evaluation of disorders of the central nervous system. The clinical usefulness of 1 H MR spectroscopy has been established for brain neoplasms, neonatal and pediatric disorders (hypoxia-ischemia, inherited metabolic diseases, and traumatic brain injury), demyelinating disorders, and infectious brain lesions. The growing list of disorders for which 1 H MR spectroscopy may contribute to patient management extends to neurodegenerative diseases, epilepsy, and stroke. To facilitate expanded clinical acceptance and standardization of MR spectroscopy methodology, guidelines are provided for data acquisition and analysis, quality assessment, and interpretation. Finally, the authors offer recommendations to expedite the use of robust MR spectroscopy methodology in the clinical setting, including incorporation of technical advances on clinical units.q RSNA, 2014 Online supplemental material is available for this article. G.O. (e-mail: gulin@cmrr.umn.edu). 2 The complete list of authors and affiliations is at the end of this article.q RSNA, 2014 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights. Radiology H MR Spectrum of the Brain: Metabolites and Their Biomarker PotentialMR spectroscopy provides a very different basic "readout" than MR imaging, namely a spectrum rather than an techniques were developed. These early localization techniques included pointresolved spectroscopy (PRESS) (1,2) and stimulated echo acquisition mode (STEAM) (3), methods that are now widely used in clinical MR spectroscopy applications.Preliminary studies revealed large differences in metabolite levels in acute stroke (4), chronic multiple sclerosis (5), and brain tumors compared with healthy brain (6). Although this work stimulated a surge of interest in 1 H MR spectroscopy for diagnosing and assessing CNS disorders during the early days of the "Decade of the Brain" (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999), many suboptimal patient studies (7) and the lack of consistent guidelines have led to a situation where, 20 years later, MR spectroscopy is still considered an "investigational technique" by some medical professionals and health care organizations. However, the ability to make an early, noninvasive diagnosis or to increase confidence in a suspected diagnosis is highly valued by patients and clinicians alike. As a result, an increasing number of imaging centers are incorporating MR spectroscopy into their clinical protocols for brain...

Compared with use of T2-weighted MR imaging, use of dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging facilitated significantly improved accuracy in prostate cancer localization.

MR scanners with a magnetic field strength of 3T are becoming more and more available to the scientific and clinical community. The intrinsic increase in signal-tonoise ratio (SNR) when moving to higher field strengths creates better possibilities for using MR spectroscopy in characterizing brain pathologies within clinically acceptable measurement times. Moreover, the chemical shift dispersion (in Hertz) between different resonances increases linearly with field strength.As the distribution of metabolites can be heterogeneous, especially in local pathologies (e.g., brain tumors), twodimensional (2D) or three-dimensional (3D) 1 H-MR spectroscopic imaging (MRSI) (1) is the preferred spectroscopic examination method. MRSI can cover a large part of the brain and simultaneously localize metabolite signals into small voxels.One of the important markers in brain pathologies is the lipid content. To prevent contamination of signals from voxels within the brain with lipid signals from subcutaneous tissue outside the brain, an accurate suppression of lipid signals from subcutaneous tissue around the skull is required. This can be achieved in different ways. First of all, with a point-resolved spectroscopy (PRESS) pulse sequence (2) a volume of interest (VOI) is excited with three orthogonal slice-selective pulses excluding the skull. Second, remaining undesired signals can be suppressed with outer volume saturation slabs before excitation of the VOI. Third, in MRSI a combination of weighted elliptical kspace sampling and apodization of k-space before Fourier transformation can reduce voxel bleed to a minimum, while sensitivity is maintained (3,4).An often-underestimated problem with proton MRSI is the chemical shift artifact or chemical shift displacement error (CSDE). Signals with different chemical shifts experience different slice selections: the combination of the bandwidth of the radio frequency (RF) pulse, the chemical shift of the metabolite of interest, and the strength of the selective gradient define the exact slice selection for every individual signal. With a trend toward signal excitation with large body coils (and signal reception with multichannel array coils), bandwidths of conventional RF pulses become quite small. As the chemical shift (in Hertz) increases with magnetic field, the CSDE at 3T can become very large, if unaccounted for. One solution to this problem is using OVERPRESS (General Electric terminology), also known as fully-excited VOI (Siemens terminology): the excited volume is deliberately chosen to be in the order of 20% larger than the VOI (5), and signals from outside the VOI are suppressed with outer volume saturation pulses, e.g., very selective suppression pulses with large bandwidths (6). A different solution to this problem can be found in using RF pulses with large bandwidths to excite and refocus the MR signals of interest themselves, instead of suppressing unwanted signals from outside the VOI. Adiabatic RF pulses have large bandwidths, and were originally introduced in the MR fiel...

Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.

Image quality and localization improved significantly with ERC imaging compared with BAC imaging. For experienced radiologists, the staging performance was significantly better with ERC imaging.