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Objectives: The purpose of this work was to improve the clinical versatility of high-speed real-time MRI studies of temporomandibular joint (TMJ) dynamics by simultaneous recordings of multiple MRI movies in different sections., Methods: Real-time MRI at 3 T was realized using highly undersampled radial FLASH acquisitions and image reconstruction by regularized nonlinear inversion (NLINV). Multi-slice real-time MRI of two, three or four slices at 0.75 mm resolution and 6 to 8 mm thickness was accomplished at 50.0 ms, 33.3 ms or 25.5 ms temporal resolution, respectively, yielding simultaneous movies at 2 × 10, 3 × 10 or 4 × 10 frames per second in a frame-interleaved acquisition mode. Real-time MRI movies were evaluated by three blinded raters for visibility of the anterior and posterior border of disc, shape of the disk body and condyle head as well as movement of the disc and condyle (1 = excellent, 5 = no visibility)., Results: Effective delineation of the disk atop the mandibular condyle was achieved by T 1 -weighted images with opposed-phase water-fat contrast. Compared to 8 mm sections, multi-slice recordings with 6 mm thickness provided sharper delineation of relevant structures as confirmed by inter-rater evaluation. Respective dual-slice and triple-slice recordings of a single TMJ as well as dual-slice recordings of both joints (one slice per TMJ) received the highest visibility ratings of ≤ 2 corresponding to high confidence in diagnostic content., Conclusions: The improved access to TMJ dynamics by multi-slice real-time MRI will contribute to more effective treatment of temporomandibular disorders.

Purpose: To develop a high-speed multislice T1 mapping method based on a single-shot inversion-recovery (IR) radial FLASH acquisition and a regularized model-based reconstruction., Methods: Multislice radial k-space data are continuously acquired after a single nonselective inversion pulse using a golden-angle sampling scheme in a spoke-interleaved manner with optimized flip angles. Parameter maps and coil sensitivities of each slice are estimated directly from highly undersampled radial k-space data using a model-based nonlinear inverse reconstruction in conjunction with joint sparsity constraints. The performance of the method has been validated using a numerical and experimental T1 phantom as well as demonstrated for studies of the human brain and liver at 3T., Results: The proposed method allows for 7 simultaneous T1 maps of the brain at 0.5 × 0.5 × 4 mm 3 resolution within a single IR experiment of 4 s duration. Phantom studies confirm similar accuracy and precision as obtained for a single-slice acquisition. For abdominal applications, the proposed method yields three simultaneous T1 maps at 1.25 × 1.25 × 6 mm 3 resolution within a 4 s breath hold., Conclusion: Rapid, robust, accurate, and precise multislice T1 mapping may be achieved by combining the advantages of a model-based nonlinear inverse reconstruction, radial sampling, parallel imaging, and compressed sensing.

The purpose of this study was to assess the reproducibility of functional and anatomical parameters of swallowing events as determined by real-time MRI at 40 ms temporal resolution (25 frames per second). Twenty-three consecutive patients with gastroesophageal reflux disease (GERD) underwent real-time MRI of the gastroesophageal junction at 3.0 T. Real-time MRI was based on highly undersampled radial fast low angle shot (FLASH) acquisitions with iterative image reconstruction by regularized nonlinear inversion (NLINV). MRI movies visualized the esophageal transport of a pineapple juice bolus, its passage through the gastroesophageal junction and functional responses during a Valsalva maneuver. His-angle, sphincter position, sphincter length and sphincter transit time were assessed by two radiologists. Interobserver and intraobserver intraclass correlation coefficients (ICC) were evaluated and Bland-Altman plots were constructed to assess the observer agreement. Interobserver agreement was excellent for sphincter transit time (ICC = 0.92), His-angle (ICC = 0.93), His-angle during Valsalva maneuver (ICC = 0.91) and sphincter-to-diaphragm distance (ICC = 0.98). Sphincter length and oesophageal diameter showed good interobserver agreement (ICC = 0.62 and ICC = 0.70). Intraobserver agreement was good for sphincter length (ICC = 0.80) and excellent for sphincter transit time, His-angle and His-angle during Valsalva maneuver, sphincter-to-diaphragm distance, and esophageal diameter (ICC = 0.91; ICC = 0.97; ICC = 0.97; ICC = 0.998; ICC = 0.93). All functional parameters of the gastroesophageal junction had good to excellent reproducibility. Visual assessment of Bland Altman plots did not reveal any systematic interobserver bias. In conclusion, the visualization of swallowing events by real-time MRI has a high potential for clinical application in gastroesophageal reflux disease., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purpose: The development of a calibrationless parallel imaging method for accelerated simultaneous multi-slice (SMS) MRI based on Regularized Nonlinear Inversion (NLINV), evaluated using Cartesian and radial fast low-angle shot (FLASH)., Theory and Methods: NLINV is a parallel imaging method that jointly estimates image content and coil sensitivities using a Newton-type method with regularization. Here, NLINV is extended to SMS-NLINV for reconstruction and separation of all simultaneously acquired slices. The performance of the extended method is evaluated for different sampling schemes using phantom and in vivo experiments based on Cartesian and radial SMS-FLASH sequences., Results: The basic algorithm was validated in Cartesian experiments by comparison with ESPIRiT. For Cartesian and radial sampling, improved results are demonstrated compared to single-slice experiments, and it is further shown that sampling schemes using complementary samples outperform schemes with the same samples in each partition., Conclusion: The extension of the NLINV algorithm for SMS data was implemented and successfully demonstrated in combination with a Cartesian and radial SMS-FLASH sequence. Magn Reson Med 79:2057-2066, 2018. © 2017 International Society for Magnetic Resonance in Medicine., (© 2017 International Society for Magnetic Resonance in Medicine.)

Purpose: To develop a model-based reconstruction technique for single-shot T 1 mapping with high spatial resolution, accuracy, and precision using an inversion-recovery (IR) fast low-angle shot (FLASH) acquisition with radial encoding., Methods: The proposed model-based reconstruction jointly estimates all model parameters, that is, the equilibrium magnetization, steady-state magnetization, 1/ T1*, and all coil sensitivities from the data of a single-shot IR FLASH acquisition with a small golden-angle radial trajectory. Joint sparsity constraints on the parameter maps are exploited to improve the performance of the iteratively regularized Gauss-Newton method chosen for solving the nonlinear inverse problem. Validations include both a numerical and experimental T 1 phantom, as well as in vivo studies of the human brain and liver at 3 T., Results: In comparison to previous reconstruction methods for single-shot T 1 mapping, which are based on real-time MRI with pixel-wise fitting and a model-based approach with a predetermination of coil sensitivities, the proposed method presents with improved robustness against phase errors and numerical precision in both phantom and in vivo studies., Conclusion: The comprehensive model-based reconstruction with L1 regularization offers rapid and robust T 1 mapping with high accuracy and precision. The method warrants accelerated computing and online implementation for extended clinical trials. Magn Reson Med 79:730-740, 2018. © 2017 International Society for Magnetic Resonance in Medicine., (© 2017 International Society for Magnetic Resonance in Medicine.)

The purpose of this work is to develop an automatic method for the scaling of unknowns in model-based nonlinear inverse reconstructions and to evaluate its application to real-time phase-contrast (RT-PC) flow magnetic resonance imaging (MRI). Model-based MRI reconstructions of parametric maps which describe a physical or physiological function require the solution of a nonlinear inverse problem, because the list of unknowns in the extended MRI signal equation comprises multiple functional parameters and all coil sensitivity profiles. Iterative solutions therefore rely on an appropriate scaling of unknowns to numerically balance partial derivatives and regularization terms. The scaling of unknowns emerges as a self-adjoint and positive-definite matrix which is expressible by its maximal eigenvalue and solved by power iterations. The proposed method is applied to RT-PC flow MRI based on highly undersampled acquisitions. Experimental validations include numerical phantoms providing ground truth and a wide range of human studies in the ascending aorta, carotid arteries, deep veins during muscular exercise and cerebrospinal fluid during deep respiration. For RT-PC flow MRI, model-based reconstructions with automatic scaling not only offer velocity maps with high spatiotemporal acuity and much reduced phase noise, but also ensure fast convergence as well as accurate and precise velocities for all conditions tested, i.e. for different velocity ranges, vessel sizes and the simultaneous presence of signals with velocity aliasing. In summary, the proposed automatic scaling of unknowns in model-based MRI reconstructions yields quantitatively reliable velocities for RT-PC flow MRI in various experimental scenarios., (Copyright © 2017 John Wiley & Sons, Ltd.)

Objective: Movements inside the oral cavity during lip trilling in horn-playing are poorly understood and controversial, particularly with respect to pedagogy. Developments in real-time magnetic resonance imaging (RT-MRI) allow representations of oral cavity movement during lip trill performance on a MRI-compatible horn to be recorded and quantified., Methods: We present RT-MRI data on 11 highly skilled horn players obtained from serial images acquired at acquisition times of 33.3, 18.2, and 10.0 ms (i.e., at 30, 55 and 100 frames/sec) as they performed sixteenth note, whole-step trills between Eb4 and F4 (concert pitch) at two tempos, ~60 bpm and as fast as possible., Results: For fast trilling (mean speed 178.3±24.7 bpm), 7 of 11 subjects exclusively utilized a tongue movement strategy, 3 used both a tongue and jaw strategy, and 1 exclusively used a jaw strategy. For trilling at ~60 bpm, all 11 subjects used a tongue movement strategy., Conclusions: We suggest using these movement strategies in teaching whole-step trills.

Objective: The aim of this study was to develop a rapid diffusion-weighted (DW) magnetic resonance imaging (MRI) technique for whole-brain studies without susceptibility artifacts and measuring times below 3 minutes., Materials and Methods: The proposed method combines a DW spin-echo module with a single-shot stimulated echo acquisition mode MRI sequence. Previous deficiencies in image quality due to limited signal-to-noise ratio are compensated for (1) by radial undersampling to enhance the flip angle and thus the signal strength of stimulated echoes; (2) by defining the image reconstruction as a nonlinear inverse problem, which is solved by the iteratively regularized Gauss-Newton method; and (3) by denoising with use of a modified nonlocal means filter. The method was implemented on a 3 T MRI system (64-channel head coil, 80 mT · m gradients) and evaluated for 10 healthy subjects and 2 patients with an ischemic lesion and epidermoid cyst, respectively., Results: High-quality mean DW images of the entire brain were obtained by acquiring 1 non-DW image and 6 DW images with different diffusion directions at b = 1000 s · mm. The achievable resolution for a total measuring time of 84 seconds was 1.5 mm in plane with a section thickness of 4 mm (55 sections). A measuring time of 168 seconds allowed for an in-plane resolution of 1.25 mm and a section thickness of 3 mm (54 sections). Apparent diffusion coefficient values were in agreement with literature data., Conclusions: The proposed method for DW MRI offers immunity against susceptibility problems, high spatial resolution, adequate signal-to-noise ratio and clinically feasible scan times of less than 3 minutes for whole-brain studies. More extended clinical trials require accelerated computation and online reconstruction.

Purpose: To develop a model-based reconstruction technique for real-time phase-contrast flow MRI with improved spatiotemporal accuracy in comparison to methods using phase differences of two separately reconstructed images with differential flow encodings., Methods: The proposed method jointly computes a common image, a phase-contrast map, and a set of coil sensitivities from every pair of flow-compensated and flow-encoded datasets obtained by highly undersampled radial FLASH. Real-time acquisitions with five and seven radial spokes per image resulted in 25.6 and 35.7 ms measuring time per phase-contrast map, respectively. The signal model for phase-contrast flow MRI requires the solution of a nonlinear inverse problem, which is accomplished by an iteratively regularized Gauss-Newton method. Aspects of regularization and scaling are discussed. The model-based reconstruction was validated for a numerical and experimental flow phantom and applied to real-time phase-contrast MRI of the human aorta for 10 healthy subjects and 2 patients., Results: Under all conditions, and compared with a previously developed real-time flow MRI method, the proposed method yields quantitatively accurate phase-contrast maps (i.e., flow velocities) with improved spatial acuity, reduced phase noise and reduced streaking artifacts., Conclusion: This novel model-based reconstruction technique may become a new tool for clinical flow MRI in real time. Magn Reson Med 77:1082-1093, 2017. © 2016 International Society for Magnetic Resonance in Medicine., (© 2016 International Society for Magnetic Resonance in Medicine.)

Objective: The functional role of the glottis in brass performance is poorly understood and controversial, particularly with respect to pedagogy. Technological limitations have prevented the non-invasive, systematic study of the glottis in the past, but developments in real-time magnetic resonance imaging (RT-MRI) allow representations of glottal movement during performance on a MRI-compatible horn to be recorded and quantified., Methods: We present RT-MRI data obtained on 6 advanced-level horn players from serial images acquired at an acquisition time of 33.3 ms as they performed sustained note exercises on three notes (concert Eb2, Eb4, and Bb4) at each of three dynamics (pp, mf, and ff) and a staccato exercise. An advanced-level trumpet player was also studied performing a modification of the staccato exercise designed to minimize vertical movement of the larynx. Glottal movements and positions in the coronal plane were analyzed using a customized MATLAB toolkit., Results: In sustained note playing, there is a significant influence of dynamic on the degree of glottal adduction/abduction. There is greater adduction with softer notes, and greater abduction with louder notes. In slow staccato playing, glottal closure accompanies the cessation of each note and persists until iteration of the next note in the sequence., Conclusions: We demonstrate that RT-MRI provides a suitable method to identify and quantify glottal movement during horn playing. We further show that there is a direct relationship between dynamic level and glottal adduction/abduction, and that the glottis is involved in performing notes during slow staccato playing.

Purpose: To develop generic optimization strategies for image reconstruction using graphical processing units (GPUs) in magnetic resonance imaging (MRI) and to exemplarily report on our experience with a highly accelerated implementation of the nonlinear inversion (NLINV) algorithm for dynamic MRI with high frame rates., Methods: The NLINV algorithm is optimized and ported to run on a multi-GPU single-node server. The algorithm is mapped to multiple GPUs by decomposing the data domain along the channel dimension. Furthermore, the algorithm is decomposed along the temporal domain by relaxing a temporal regularization constraint, allowing the algorithm to work on multiple frames in parallel. Finally, an autotuning method is presented that is capable of combining different decomposition variants to achieve optimal algorithm performance in different imaging scenarios., Results: The algorithm is successfully ported to a multi-GPU system and allows online image reconstruction with high frame rates. Real-time reconstruction with low latency and frame rates up to 30 frames per second is demonstrated., Conclusion: Novel parallel decomposition methods are presented which are applicable to many iterative algorithms for dynamic MRI. Using these methods to parallelize the NLINV algorithm on multiple GPUs, it is possible to achieve online image reconstruction with high frame rates.

Background: The accurate assessment of peripheral venous flow is important for the early diagnosis and treatment of disorders such as deep-vein thrombosis (DVT) which is a major cause of post-thrombotic syndrome or even death due to pulmonary embolism. The aim of this work is to quantitatively determine blood flow in deep veins during rest and muscular exercise using a novel real-time magnetic resonance imaging (MRI) method for velocity-encoded phase-contrast (PC) MRI at high spatiotemporal resolution., Methods: Real-time PC MRI of eight healthy volunteers and one patient was performed at 3 Tesla (Prisma fit, Siemens, Erlangen, Germany) using a flexible 16-channel receive coil (Variety, NORAS, Hoechberg, Germany). Acquisitions were based on a highly undersampled radial FLASH sequence with image reconstruction by regularized nonlinear inversion at 0.5×0.5×6 mm 3 spatial resolution and 100 ms temporal resolution. Flow was assessed in two cross-sections of the lower leg at the level of the calf muscle and knee using a protocol of 10 s rest, 20 s flexion and extension of the foot, and 10 s rest. Quantitative analyses included through-plane flow in the right posterior tibial, right peroneal and popliteal vein (PC maps) as well as signal intensity changes due to flow and muscle movements (corresponding magnitude images)., Results: Real-time PC MRI successfully monitored the dynamics of venous flow at high spatiotemporal resolution and clearly demonstrated increased flow in deep veins in response to flexion and extension of the foot. In normal subjects, the maximum velocity (averaged across vessel lumen) during exercise was 9.4±5.7 cm·s -1 for the right peroneal vein, 8.5±4.6 cm·s -1 for the right posterior tibial vein and 17.8±5.8 cm·s -1 for the popliteal vein. The integrated flow volume per exercise (20 s) was 1.9, 1.6 and 50 mL (mean across subjects) for right peroneal, right posterior tibial and popliteal vein, respectively. A patient with DVT presented with peak flow velocities of only about 2 cm·s -1 during exercise and less than 1 cm·s -1 during rest., Conclusions: Real-time PC MRI emerges as a new tool for quantifying the dynamics of muscle-induced flow in deep veins. The method provides both signal intensity changes and velocity information for the assessment of blood flow and muscle movements. It now warrants extended clinical trials to patients with suspected thrombosis., Competing Interests: J Frahm is co-inventor of a patent covering the real-time MRI technique used in this study. The other authors have no conflicts of interest to declare.

Objective: To develop a novel method for rapid myocardial T 1 mapping at high spatial resolution., Methods: The proposed strategy represents a single-shot inversion recovery experiment triggered to early diastole during a brief breath-hold. The measurement combines an adiabatic inversion pulse with a real-time readout by highly undersampled radial FLASH, iterative image reconstruction and T 1 fitting with automatic deletion of systolic frames. The method was implemented on a 3-T MRI system using a graphics processing unit-equipped bypass computer for online application. Validations employed a T 1 reference phantom including analyses at simulated heart rates from 40 to 100 beats per minute. In vivo applications involved myocardial T 1 mapping in short-axis views of healthy young volunteers., Results: At 1-mm in-plane resolution and 6-mm section thickness, the inversion recovery measurement could be shortened to 3 s without compromising T 1 quantitation. Phantom studies demonstrated T 1 accuracy and high precision for values ranging from 300 to 1500 ms and up to a heart rate of 100 beats per minute. Similar results were obtained in vivo yielding septal T 1 values of 1246 ± 24 ms (base), 1256 ± 33 ms (mid-ventricular) and 1288 ± 30 ms (apex), respectively (mean ± standard deviation, n = 6)., Conclusion: Diastolic myocardial T 1 mapping with use of single-shot inversion recovery FLASH offers high spatial resolution, T 1 accuracy and precision, and practical robustness and speed. Advances in knowledge: The proposed method will be beneficial for clinical applications relying on native and post-contrast T 1 quantitation.

Purpose: To design, evaluate, and apply a bow tie antenna transceiver radiofrequency (RF) coil array tailored for cardiac MRI at 7.0 Tesla (T)., Methods: The radiofrequency (RF) coil array comprises 16 building blocks each containing a bow tie shaped λ/2-dipole antenna. Numerical simulations were used for transmission field homogenization and RF safety validation. RF characteristics were examined in a phantom study. The array's suitability for high spatial resolution two-dimensional (2D) CINE imaging and for real time imaging of the heart was examined in a volunteer study., Results: The arrays transmission fields and RF characteristics are suitable for cardiac MRI at 7.0T. The coil performance afforded a spatial resolution as good as (0.8 × 0.8 × 2.5) mm(3) for segmented 2D CINE MRI at 7.0T which is by a factor of 12 superior versus standardized protocols used in clinical practice at 1.5T. The proposed transceiver array supports 1D acceleration factors of up to R = 6 without impairing image quality significantly., Conclusion: The 16-channel bow tie antenna transceiver array supports accelerated and high spatial resolution cardiac MRI. The array is compatible with multichannel transmission and provides a technological basis for future clinical assessment of parallel transmission techniques at 7.0 Tesla. Magn Reson Med 75:2553-2565, 2016. © 2015 Wiley Periodicals, Inc., (© 2015 Wiley Periodicals, Inc.)

Objective: Motor control of the muscles of the face, lips, and tongue of horn players has traditionally been described from externally observed phenomena. Developments in real-time, high-speed magnetic resonance imaging (MRI) extend the scope of study to include descriptive and quantitative information from within the mouth. We employed these developments to compare oral movement strategies between 12 elite horn players and 5 horn players with embouchure dystonia (ED)., Methods: Serial images with an acquisition time of 33.3 ms were obtained from each subject as they performed 6 exercises on an MRI-compatible horn: 1) a slurred ascending harmonic sequence, 2) a slurred descending harmonic sequence, 3-6) sustained high and low notes, each performed softly and loudly. Temporal changes in pixel luminescence along a series of lines positioned within the oral cavity were calculated using a customized MATLAB toolkit. This allowed the extraction of temporal line profiles for comparative analyses between elite and dystonic horn players., Results: Differing motor strategies of controlling the tongue and jaw were observed during ascending and descending exercises. In ascending exercises, the elite players employed a strategy of elevation and anterior tongue displacement and elevation of the jaw, whereas dystonic players exhibited more variability in their responses. With descending exercises, both groups exhibited a lowering of the tongue and jaw, though this was more pronounced and consistent in the elite horn players. Sustained note exercises also elicited differences between groups. We suggest that elite strategies are more efficient and that the less-efficient patterns of dystonic players may exacerbate muscular tension with ED.

Purpose: To develop a method for spoiling transverse magnetizations without additional gradients to minimize repetition times for radial fast low angle shot (FLASH) MRI., Methods: Residual steady state transverse magnetizations and corresponding image artifacts were analyzed for radial gradient echo sequences with constant and randomized RF phases in comparison with a sequence with refocused frequency-encoding gradients, constant spoiler gradient, and conventional RF spoiling (gold standard). The spoiling performance was assessed for different radial trajectories using numerical simulations, phantom experiments, and in vivo MRI studies of the human brain., Results: Simulations as well as phantom and in vivo measurements reveal a highly efficient spoiling capacity for randomized RF phases and radial FLASH sequences without the need for gradient rewinding and spoiler gradients. The data also demonstrate a strong dependence of the spoiling performance on the chosen radial trajectory (ie, the azimuthal angular increment between successive projections) with excellent results for an interleaved multiturn scheme., Conclusion: Effective spoiling of transverse magnetizations in radial FLASH MRI may be achieved by randomized RF phases without additional spoiler gradients. The technique allows for short repetition times as required for high-speed real-time MRI., (© 2015 Wiley Periodicals, Inc.)

Purpose: To provide multidimensional velocity compensation for real-time phase-contrast flow MRI., Methods: The proposed method introduces asymmetric gradient echoes for highly undersampled radial FLASH MRI with phase-sensitive image reconstruction by regularized nonlinear inversion (NLINV). Using an adapted gradient delay correction the resulting image quality was analyzed by simulations and experimentally validated at 3 Tesla. For real-time flow MRI the reduced gradient-echo timing allowed for the incorporation of velocity-compensating waveforms for all imaging gradients at even shorter repetition times., Results: The results reveal a usable degree of 20% asymmetry. Real-time flow MRI with full velocity compensation eliminated signal void in a flow phantom, confirmed flow parameters in healthy subjects and demonstrated signal recovery and phase conservation in a patient with aortic valve insufficiency and stenosis. Exemplary protocols at 1.4-1.5 mm resolution and 6 mm slice thickness achieved total acquisition times of 33.3-35.7 ms for two images (7 spokes each) with and without flow-encoding gradient., Conclusion: Asymmetric gradient echoes were successfully implemented for highly undersampled radial trajectories. The resulting temporal gain offers full velocity compensation for real-time phase-contrast flow MRI which minimizes false-positive contributions from complex flow and further enhances the temporal resolution compared with acquisitions with symmetric echoes., (© 2015 Wiley Periodicals, Inc.)

Background: This paper describes the use of real-time magnetic resonance imaging in visualizing and quantifying oral cavity motor strategies employed by 6 healthy, elite horn players and 5 horn players with embouchure dystonia., Methods: Serial images with an acquisition time of 33.3 ms were obtained from each performer during execution of an 11-note harmonic series encompassing 2.5 octaves on a magnetic resonance imaging-compatible horn. A customized MATLAB toolkit was employed for the extraction of line profiles from magnetic resonance imaging films allowing comparative analyses between elite and dystonic horn players., Results: The data demonstrate differing motor strategies, particularly in moving from the 6th through 9th harmonics. The elite horn player strategy features elevation and anterior displacement of the tongue during ascending sequences, whereas dystonic players showed significantly less movement. The elite horn players thus narrowed the air channel on higher notes, presumably affording faster airflow for vibration of the lips at higher frequencies., Conclusions: We postulate that failure to employ this strategy by dystonic horn players may require greater tension in the embouchure muscles to compensate for slower air speed. Though this may simply be an expression of or adaptation for dystonia, the possibility that it may be a contributing factor in the development of embouchure dystonia is suggested.

This prospective study of eight healthy volunteers evaluates peak flow velocities (PFV) in the ascending aorta using real-time phase-contrast magnetic resonance imaging (MRI) in comparison to cine phase-contrast MRI and echocardiography. Flow measurements by echocardiography and cine phase-contrast MRI with breath-holding were performed according to clinical standards. Real-time phase-contrast MRI at 40 ms temporal resolution and 1.3 mm in-plane resolution was based on highly undersampled radial fast low-angle shot (FLASH) sequences with image reconstruction by regularized nonlinear inversion (NLINV). Evaluations focused on the determination of PFV. Linear regressions and Bland-Altman plots were used for comparisons of methods. When averaged across subjects, real-time phase-contrast MRI resulted in PFV of 120±20 cm s(-1) (mean ± SD) in comparison to 122±16 cm s(-1) for cine MRI and 124±20 cm s(-1) for echocardiography. The maximum deviations between real-time phase-contrast MRI and echocardiography ranged from -20 to +14 cm s(-1) (cine MRI: -10 to +12 cm s(-1)). Thus, in general, real-time phase-contrast MRI of cardiac outflow revealed quantitative agreement with cine MRI and echocardiography. The advantages of real-time MRI are measurements during free breathing and access to individual cardiac cycles.

Purpose: To develop and evaluate a practical phase unwrapping method for real-time phase-contrast flow MRI using temporal and spatial continuity., Methods: Real-time phase-contrast MRI of through-plane flow was performed using highly undersampled radial FLASH with phase-sensitive reconstructions by regularized nonlinear inversion. Experiments involved flow in a phantom and the human aorta (10 healthy subjects) with and without phase wrapping for velocity encodings of 100 cm·s(-1) and 200 cm·s(-1) . Phase unwrapping was performed for each individual cardiac cycle and restricted to a region of interest automatically propagated to all time frames. The algorithm exploited temporal continuity in forward and backward direction for all pixels with a "continuous" representation of blood throughout the entire cardiac cycle (inner vessel lumen). Phase inconsistencies were corrected by a comparison with values from direct spatial neighbors. The latter approach was also applied to pixels exhibiting a discontinuous signal intensity time course due to movement-induced spatial displacements (peripheral vessel zone)., Results: Phantom and human flow MRI data were successfully unwrapped. When halving the velocity encoding, the velocity-to-noise ratio (VNR) increased by a factor of two., Conclusion: The proposed phase unwrapping method for real-time flow MRI allows for measurements with reduced velocity encoding and increased VNR., (© 2014 Wiley Periodicals, Inc.)

Auditory cortex (AC) contains several primary-like, or "core," fields, which receive thalamic input and project to non-primary "belt" fields. In humans, the organization and layout of core and belt auditory fields are still poorly understood, and most auditory neuroimaging studies rely on macroanatomical criteria, rather than functional localization of distinct fields. A myeloarchitectonic method has been suggested recently for distinguishing between core and belt fields in humans (Dick F, Tierney AT, Lutti A, Josephs O, Sereno MI, Weiskopf N. 2012. In vivo functional and myeloarchitectonic mapping of human primary auditory areas. J Neurosci. 32:16095-16105). We propose a marker for core AC based directly on functional magnetic resonance imaging (fMRI) data and pattern classification. We show that a portion of AC in Heschl's gyrus classifies sound frequency more accurately than other regions in AC. Using fMRI data from macaques, we validate that the region where frequency classification performance is significantly above chance overlaps core auditory fields, predominantly A1. Within this region, we measure tonotopic gradients and estimate the locations of the human homologues of the core auditory subfields A1 and R. Our results provide a functional rather than anatomical localizer for core AC. We posit that inter-individual variability in the layout of core AC might explain disagreements between results from previous neuroimaging and cytological studies., (© The Author 2014. Published by Oxford University Press.)

This paper describes the use of high-speed real-time (RT) magnetic resonance imaging (MRI) in quantifying very rapid motor function within the oropharyngeal cavity of six elite horn players. Based on simultaneous sound recordings, the efficacy of RT-MRI films at 30 and 100 frames per second (fps) was assessed for tongue movements associated with double tonguing performance. Serial images with a nominal temporal resolution of 10.0 and 33.3 ms were obtained by highly undersampled radial fast low-angle shot (FLASH) sequences (5 and 17 spokes, respectively) using complementary sets of spokes for successive acquisitions (extending over 9 and 5 frames, respectively). Reconstructions of high-speed images were obtained by temporally regularized nonlinear inversion (NLINV) as previously described. A customized MATLAB toolkit was developed for the extraction of line profiles from MRI films to quantify temporal phenomena associated with task performance. The analyses reveal that for the present setting, which required the use of a temporal median filter to optimize image quality, acquisition rates of 30 fps are inadequate to accurately detect tongue movements during double tonguing, but that rates of 100 fps do allow for a precise quantification of movement. These data for the first time demonstrate the extreme performance of elite horn players. High-speed RT-MRI offers so far unavailable opportunities to study the oropharyngeal movements during brass playing with future potential for teaching and the treatment of patients suffering from dystonia.

Purpose: Ifosfamide-induced encephalopathy is a neurotoxic adverse effect of ifosfamide chemotherapy. The objective of this study was to determine the incidence of encephalopathy in patients with lymphoma and sarcoma receiving ifosfamide chemotherapy and assess for potential risk factors that influence the incidence of encephalopathy., Methods: A retrospective study of sarcoma and lymphoma patients receiving ifosfamide chemotherapy was performed at the participating institutions. Enrollment began 1 July 2011 and continued chronologically backwards until 100 sarcoma and 100 lymphoma patients were enrolled. Identification of ifosfamide-induced encephalopathy events was performed by reviewing provider documentation of ifosfamide infusions. Logistic regression was employed to determine associations between risk factors and ifosfamide-induced encephalopathy events., Results: Of the 200 patients enrolled, 29 (14.5%) patients experienced encephalopathy. Ifosfamide-induced encephalopathy occurred more frequently in the sarcoma population than the lymphoma population (24 vs. 5 patients, p < 0.001). In addition to cancer type, prior use of cisplatin, concomitant opioids, and use of CYP2B6 inhibitors remained as significant variables in the multivariate model conferring a 12.47, 2.81, and 5.17 increased odds of experiencing encephalopathy, respectively. The odds of experiencing encephalopathy were 9.0 and 1.37 times higher for a one-unit increase in serum creatinine and hemoglobin, respectively, and 0.15 times lower for a one-unit increase in albumin., Conclusions: This is the first study to demonstrate that patients with sarcoma experienced ifosfamide-induced encephalopathy more often than those with lymphoma. For all patients, predisposing factors for ifosfamide-induced encephalopathy included previous cisplatin exposure, concomitant opioids and CYP2B6 inhibitors. Laboratory values that increased ifosfamide-induced encephalopathy risk included low serum albumin, increased serum creatinine, and increased hemoglobin., (© The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Cardiac structure, function and flow are most commonly studied by ultrasound, X-ray and magnetic resonance imaging (MRI) techniques. However, cardiovascular MRI is hitherto limited to electrocardiogram (ECG)-synchronized acquisitions and therefore often results in compromised quality for patients with arrhythmias or inabilities to comply with requested protocols-especially with breath-holding. Recent advances in the development of novel real-time MRI techniques now offer dynamic imaging of the heart and major vessels with high spatial and temporal resolution, so that examinations may be performed without the need for ECG synchronization and during free breathing. This article provides an overview of technical achievements, physiological validations, preliminary patient studies and translational aspects for a future clinical scenario of cardiovascular MRI in real time.

Purpose: To evaluate a novel real-time phase-contrast magnetic resonance imaging (MRI) technique for the assessment of through-plane flow in the ascending aorta., Materials and Methods: Real-time MRI was based on a radial fast low-angle shot (FLASH) sequence with about 30-fold undersampling and image reconstruction by regularized nonlinear inversion. Phase-contrast maps were obtained from two (interleaved or sequential) acquisitions with and without a bipolar velocity-encoding gradient. Blood flow in the ascending aorta was studied in 10 healthy volunteers at 3 T by both real-time MRI (15 sec during free breathing) and electrocardiogram (ECG)-synchronized cine MRI (with and without breath holding). Flow velocities and stroke volumes were evaluated using standard postprocessing software., Results: The total acquisition time for a pair of phase-contrast images was 40.0 msec (TR/TE = 2.86/1.93 msec, 10° flip angle, 7 spokes per image) for a nominal in-plane resolution of 1.3 mm and a section thickness of 6 mm. Quantitative evaluations of spatially averaged flow velocities and stroke volumes were comparable for real-time and cine methods when real-time MRI data were averaged across heartbeats. For individual heartbeats real-time phase-contrast MRI resulted in higher peak velocities for values above 120 cm s(-1)., Conclusion: Real-time phase-contrast MRI of blood flow in the human aorta yields functional parameters for individual heartbeats. When averaged across heartbeats real-time flow velocities and stroke volumes are comparable to values obtained by conventional cine MRI., (© 2013 Wiley Periodicals, Inc.)

Patient safety has become a major focus in German socio-political awareness over the past decade. Efforts to improve patient safety have been increased nationwide and involve all stakeholders in the German health care system. The government aims to improve the quality of health care services both in the hospital and in the ambulatory care sector with a quality campaign. On one hand it strengthens patients' power and participation in decision-making and on the other hand it stresses the need for health care providers themselves to enhance patient safety and to ensure the nationwide provision of excellent health care, whereby hospitals play a vital role in providing a comprehensive system of locally available clinical treatment. This article focuses particularly on the numerous mandatory and voluntary initiatives provided by hospitals with respect to quality of care and patient safety, however further information about the context can be found in the online version cited in the footnote below.

Background: While cardiovascular magnetic resonance (CMR) commonly employs ECG-synchronized cine acquisitions with balanced steady-state free precession (SSFP) contrast at 1.5 T, recent developments at 3 T demonstrate significant potential for T1-weighted real-time imaging at high spatiotemporal resolution using undersampled radial FLASH. The purpose of this work was to combine both ideas and to evaluate a corresponding real-time CMR method at 1.5 T with SSFP contrast., Methods: Radial gradient-echo sequences with fully balanced gradients and at least 15-fold undersampling were implemented on two CMR systems with different gradient performance. Image reconstruction by regularized nonlinear inversion (NLINV) was performed offline and resulted in real-time SSFP CMR images at a nominal resolution of 1.8 mm and with acquisition times of 40 ms., Results: Studies of healthy subjects demonstrated technical feasibility in terms of robustness and general image quality. Clinical applicability with access to quantitative evaluations (e.g., ejection fraction) was confirmed by preliminary applications to 27 patients with typical indications for CMR including arrhythmias and abnormal wall motion. Real-time image quality was slightly lower than for cine SSFP recordings, but considered diagnostic in all cases., Conclusions: Extending conventional cine approaches, real-time radial SSFP CMR with NLINV reconstruction provides access to individual cardiac cycles and allows for studies of patients with irregular heartbeat.

Velocity-encoded phase-contrast MRI of cardiovascular blood flow commonly relies on electrocardiogram-synchronized cine acquisitions of multiple heartbeats to quantitatively determine the flow of an averaged cardiac cycle. Here, we present a new method for real-time phase-contrast MRI that combines flow-encoding gradients with highly undersampled radial fast low-angle shot acquisitions and phase-sensitive image reconstructions by regularized nonlinear inversion. Apart from calibration studies using steady and pulsatile flow, preliminary in vivo applications focused on through-plane flow in the ascending aorta of healthy subjects. With bipolar velocity-encoding gradients of alternating polarity that overlap the slice-refocusing gradient, the method yields flow-encoded images with an in-plane resolution of 1.8 mm, section thickness of 6 mm and measuring time at 3 T of 24 ms (TR/TE = 3.44/2.76 ms; flip angle, 10º; seven radial spokes per image). Accordingly, phase-contrast maps and corresponding velocity profiles achieve a temporal resolution of 48 ms. The evaluated peak velocities, stroke volumes, flow rates and respective variances over at least 20 consecutive heartbeats are in general agreement with literature data., (Copyright © 2011 John Wiley & Sons, Ltd.)

This work demonstrates that the principles underlying phase-contrast MRI may be used to encode spatial rather than flow information along a perpendicular dimension, if this dimension contains an MRI-visible object at only one spatial location. In particular, the situation applies to 3D mapping of curved 2D structures which requires only two projection images with different spatial phase-encoding gradients. These phase-contrast gradients define the field of view and mean spin-density positions of the object in the perpendicular dimension by respective phase differences. When combined with highly undersampled radial fast low angle shot (FLASH) and image reconstruction by regularized nonlinear inversion, spatial phase-contrast MRI allows for dynamic 3D mapping of 2D structures in real time. First examples include 3D MRI movies of the acting human hand at a temporal resolution of 50 ms. With an even simpler technique, 3D maps of curved 1D structures may be obtained from only three acquisitions of a frequency-encoded MRI signal with two perpendicular phase encodings. Here, 3D MRI movies of a rapidly rotating banana were obtained at 5 ms resolution or 200 frames per second. In conclusion, spatial phase-contrast 3D MRI of 2D or 1D structures is respective two or four orders of magnitude faster than conventional 3D MRI., (Copyright © 2011 Wiley-Liss, Inc.)

Objective: To analyze the differences between ondansetron and palonosetron in healthcare resource use (i.e., inpatient/ outpatient encounters) among patients receiving intraperitoneal cisplatin., Method: A medical record review was performed. Intraperitoneal cisplatin administrations for gynecological cancers from January through June 2006 and from October 2007 through June 2008 were divided into two groups based on the serotonin-receptor antagonist used. The occurrence of chemotherapy-induced nausea and vomiting (CINV)-related hospital readmissions, emergency department visits, and outpatient encounters occurring within 7 days after cisplatin administration was compared. CINV-related resource use was defined as events associated with dehydration, hypovolemia, nausea/vomiting, hypokalemia, constipation, shortness of breath, or syncope/collapse., Results: Ondansetron or palonosetron was used in 39 and 89 cisplatin administrations, respectively. The baseline characteristics were similar between the groups with mean age of 59 years and ovarian cancer being the most common cancer. Length of stay was approximately 2 days. Palonosetron was always administered as a single-day therapy while one- or multi-day ondansetron therapy was administered in 27% and 73% of cycles, respectively. A trend towards more CINV-related hospitalizations with ondansetron versus palonosetron was observed (5.1% vs. 0%, p = 0.09) with no significant difference in other CINV-related encounters., Conclusion: Palonosetron was associated with a trend to a lower risk of CINV-related hospital readmission than ondansetron in patients receiving intraperitoneal cisplatin for gynecological cancers, although not statistically significant. The duration of ondansetron therapy might be suboptimal with 27% of patients receiving only 1 day of therapy during hospital stay. These findings need to be confirmed in future studies.

The desire to visualize noninvasively physiological processes at high temporal resolution has been a driving force for the development of MRI since its inception in 1973. In this article, we describe a unique method for real-time MRI that reduces image acquisition times to only 20 ms. Although approaching the ultimate limit of MRI technology, the method yields high image quality in terms of spatial resolution, signal-to-noise ratio and the absence of artifacts. As proposed previously, a fast low-angle shot (FLASH) gradient-echo MRI technique (which allows for rapid and continuous image acquisitions) is combined with a radial encoding scheme (which offers motion robustness and moderate tolerance to data undersampling) and, most importantly, an iterative image reconstruction by regularized nonlinear inversion (which exploits the advantages of parallel imaging with multiple receiver coils). In this article, the extension of regularization and filtering to the temporal domain exploits consistencies in successive data acquisitions and thereby enhances the degree of radial undersampling in a hitherto unexpected manner by one order of magnitude. The results obtained for turbulent flow, human speech production and human heart function demonstrate considerable potential for real-time MRI studies of dynamic processes in a wide range of scientific and clinical settings., (Copyright © 2010 John Wiley & Sons, Ltd.)

Fine-scale functional organization of the finger areas in the human primary somatosensory cortex was investigated by high-resolution BOLD MRI at 3 T using a multi-echo FLASH sequence with a voxel size of 2 mm(3). In six subjects independent tactile stimulation of the distal phalanx of the fingers of the right hand resulted in small circumscribed and barely overlapping activations precisely located along the posterior wall of the central sulcus. Three out of six subjects showed a complete succession of activation sites for all five fingers. The maps also allowed for the identification of individual variations in finger somatotopy. When registered onto the individual high-resolution MRI anatomy and compared with cytoarchitectonical maps, the finger representations were confirmed to lie within Brodmann area 3b as the main input region of the primary somatosensory cortex.

This paper describes the development of a novel technique for functional MRI of the human brain at 0.135 microL resolution for a whole brain section. In comparison with conventional studies at 3 mm isotropic resolution or 27 microL voxel size, the method yields an improvement by a factor of 200. To achieve optimum image quality, the approach is based on a multi-echo fast low-angle shot (FLASH) sequence with unipolar traversals of k-space in the frequency-encoding dimension and echo train shifting to avoid amplitude discontinuities in the phase-encoding dimension. These strategies ensure a smooth point-spread function and eliminate image ghosting artifacts without the need for any phase correction or other post-processing. Signal-to-noise losses due to the considerably reduced voxel sizes are compensated for by single slice acquisitions, optimized bandwidths and an experimental four-channel shoulder coil matched to the posterior portion of the head. Multi-echo FLASH studies of the human brain (2.9 T, seven echoes, 200 Hz/pixel bandwidth, effective echo time 36 ms, acquisition time 6 s) at 300 microm resolution (no interpolation) and 1.5 mm slice thickness revealed robust activations in primary visual areas in response to binocular stimulation. The new method holds promise for refined studies of the columnar organization of specific brain systems and for functional assessments of the gray matter at laminar resolution.

Context: Hysteroscopy (direct endoscopic visualization of the endometrial cavity) is used extensively in the evaluation of common gynecologic problems, such as menorrhagia and postmenopausal bleeding. However, there is a continuing debate about the value of this technology in the diagnosis of serious endometrial disease., Objective: To determine the accuracy of hysteroscopy in diagnosing endometrial cancer and hyperplasia in women with abnormal uterine bleeding., Data Sources: Relevant articles were identified through searches of the Cochrane Library, MEDLINE, and EMBASE (1984-2001), manual searches of bibliographies of known primary and review articles, and contact with manufacturers., Study Selection: Studies were selected blindly, independently, and in duplicate if accuracy of hysteroscopy was estimated in women with abnormal uterine bleeding, using histopathologic findings as a reference standard. Our search identified 3486 articles; 208 of these were deemed to be potentially eligible and were retrieved for detailed data extraction. Sixty-five primary studies were analyzed, including 26 346 women., Data Extraction: Data were abstracted on characteristics and quality from each study. Results for diagnostic accuracy were extracted to form 2 x 2 contingency tables separately for endometrial cancer and endometrial disease (cancer, hyperplasia, or both). Pooled likelihood ratios (LRs) were used as summary accuracy measures., Data Synthesis: The pretest probability of endometrial cancer was 3.9% (95% confidence interval [CI], 3.7%-4.2%). A positive hysteroscopy result (pooled LR, 60.9; 95% CI, 51.2-72.5) increased the probability of cancer to 71.8% (95% CI, 67.0%-76.6%), whereas a negative hysteroscopy result (pooled LR, 0.15; 95% CI, 0.13-0.18) reduced the probability of cancer to 0.6% (95% CI, 0.5%-0.8%). There was statistical heterogeneity in pooling of LRs, but an explanation for this could not be found in spectrum composition and study quality. The overall accuracy for the diagnosis of endometrial disease was modest compared with that of cancer, and the results were heterogeneous. The accuracy tended to be higher among postmenopausal women and in the outpatient setting., Conclusion: The diagnostic accuracy of hysteroscopy is high for endometrial cancer, but only moderate for endometrial disease (cancer or hyperplasia).

Our aim was to determine the diagnostic accuracy of endometrial thickness measurement by pelvic ultrasonography for predicting endometrial carcinoma and disease (hyperplasia and/or carcinoma) during an investigation of postmenopausal bleeding. We performed a systematic quantitative review of the available published literature, which consisted of online searching the MEDLINE and EMBASE databases (1966-2000) coupled with scanning of bibliography of known primary and review articles. The selection of studies, assessment of study quality, and extraction of data were performed in duplicate under masked conditions. Included in the analyses were 57 studies with 9031 patients. Accuracy data were summarized using likelihood ratios for various cut-off levels of abnormal endometrial thickness. The commonest cut-offs were 4 mm (9 studies) and 5 mm (21 studies), measuring both endometrial layers. None of the nine studies using the < or = 4 mm cut-off level were of good quality. Only four studies (out of the 21) used the < or = 5 mm cut-off level, which employed the best-quality criteria. Using the pooled estimates from these four studies only, a positive test result raised the probability of carcinoma from 14.0% (95% CI 13.3-14.7) to 31.3% (95% CI 26.1-36.3), while a negative test reduced it to 2.5% (95% CI 0.9-6.4). In conclusion, ultrasound measurement of endometrial thickness alone, using the best-quality studies cannot be used to accurately rule. However, a negative result at < or = 5 mm cut-off level measuring both endometrial layers in the presence of endometrial pathology rules out endometrial pathology with good certainty.

Adenoma tissues from 309 patients with active acromegaly was examined by routine light microscopy and immunohistochemistry, and selectively by electron microscopy. All adenomas were immunoreactive for growth hormone. Eighty-seven adenomas were monohormonal (28%), 58 were bihormonal (immunoreactive for growth hormone and prolactin) (19%), and 157 adenomas were plurihormonal (51%), with positivity for glyco-proteins and/or their α-subunit as well. The mean tumor size was significantly greater in monohormonal adenomas than in other adenoma types. There was no difference in invasiveness among the various adenoma types. Younger patients showed invasive tumor growth more often. Patients with densely granulated GH cell adenomas had a significantly longer duration of symptoms compared to patients with other adenoma types. More than half of the patients with sparsely granulated GH cell adenomas had a duration of less than 5 yr. There was no correlation between duration of symptoms and tumor size. The preoperative mean GH level was significantly higher in patients with sparsely granulated GH cell adenomas than in those with mixed GH/PRL cell adenomas. The preoperative mean PRL level was significantly higher in patients with bihormonal adenomas than in those with plurihormonal adenomas. There was an inverse correlation between age and preoperative GH and PRL levels. No linear correlation was found between preoperative basal GH and PRL levels. Monohormonal adenomas presented more often with suprasellar and/or parasellar extension than other adenoma types. Our data suggest a positive correlation between tumor extension and preoperative GH and PRL levels. Patients with plurihormonal adenomas were significantly older than patients with sparsely granulated GH cell adenomas and mixed GH/PRL cell adenomas. No significant difference was found between the various adenoma types and the extent of surgical removal, which depends on the degree of invasiveness, tumor size, and extrasellar tumor extension.

Pituitary adenoma tissue from patients with acromegaly (n = 286) was obtained by surgery and examined for folliculo-stellate cells by immunostaining for S100 protein. The number of immunostained cells varied from one adenoma to another. A hundred and ninety-eight pituitary adenomas (69%) contained S100 protein positive cells corresponding to folliculo-stellate cells (FSC): in 100 cases (35%), only few sparse FSC were found, in 43 cases (15%) FSC were scattered throughout the adenoma, and in 55 cases (19%) there was an abundance of FSC. There were no significant differences regarding sex or age of the patients. The relative amount of FSC vaired among different adenoma types. Plurihormonal adenomas showed the highest FSC density, whereas the majority of monohormonal adenomas contained only few or no FSC. Patients with pituitary adenomas containing scattered FSC had a significantly higher preoperative mean GH level than patients with pituitary adenomas not having FSC. There was a negative correlation between the FSC density in adenoma tissue and the preoperative mean PRL level. There was no correlation between the tumour size and the amount of FSC. Our data indicate no effect of the duration of symptoms on the FSC density and do not suggest a correlation between FSC density and the percentage of a certain hormone-secreting cell type.