Chemical Shift Effects Research Articles

Assessment of sequence dependent geometric distortion in contrast-enhanced MR images employed in stereotactic radiosurgery treatment planning

This work focuses on MR-related sequence dependent geometric distortions, which are associated with B0 inhomogeneity and patient-induced distortion (susceptibility differences and chemical shift effects), in MR images used in stereotactic radiosurgery (SRS) applications. Emphasis is put on characterizing distortion at target brain areas identified by gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) paramagnetic contrast agent uptake.A custom-made phantom for distortion detection was modified to accommodate two small cylindrical inserts, simulating small brain targets. The inserts were filled with Gd-DTPA solutions of various concentrations (0–20 mM). The phantom was scanned at 1.5 T unit using both the reversed read gradient polarity (to determine the overall distortion as reflected by the inserts centroid offset) and the field mapping (to determine B0 inhomogeneity related distortion in the vicinity of the inserts) techniques. Post-Gd patient images involving a total of 10 brain metastases/targets were also studied using a similar methodology.For the specific imaging conditions, contrast agent presence was found to evidently affect phantom insert position, with centroid offset extending up to 0.068 mm mM−1 (0.208 ppm mM−1). The Gd-DTPA induced distortion in patient images was of the order of 0.5 mm for the MRI protocol used, in agreement with the phantom results. Total localization uncertainty of metastases-targets in patient images ranged from 0.35 mm to 0.87 mm, depending on target location, with an average value of 0.54 mm (2.24 ppm). This relative wide range of target localization uncertainty results from the fact that the B0 inhomogeneity distortion vector in a specific location may add to or partly counterbalance Gd-DTPA induced distortion, thus increasing or decreasing, respectively, the total sequence dependent distortion.Although relatively small, the sequence dependent distortion in Gd-DTPA enhanced brain images can be easily taken into account for SRS treatment planning and target definition purposes by carefully inspecting both the forward and reversed polarity series.

A Multifaceted Study of Methane Adsorption in Metal–Organic Frameworks by Using Three Complementary Techniques

Methane is a promising clean and inexpensive energy alternative to traditional fossil fuels, however, its low volumetric energy density at ambient conditions has made devising viable, efficient methane storage systems very challenging. Metal-organic frameworks (MOFs) are promising candidates for methane storage. In order to improve the methane storage capacity of MOFs, a better understanding of the methane adsorption, mobility, and host-guest interactions within MOFs must be realized. In this study, methane adsorption within α-Mg3 (HCO2 )6 , α-Zn3 (HCO2 )6 , SIFSIX-3-Zn, and M-MOF-74 (M=Mg, Zn, Ni, Co) has been comprehensively examined. Single-crystal X-ray diffraction (SCXRD) experiments and DFT calculations of the methane adsorption locations were performed for α-Mg3 (HCO2 )6 , α-Zn3 (HCO2 )6 , and SIFSIX-3-Zn. The SCXRD thermal ellipsoids indicate that methane possesses significant mobility at the adsorption sites in each system. 2 H solid-state NMR (SSNMR) experiments targeting deuterated CH3 D guests in α-Mg3 (HCO2 )6 , α-Zn3 (HCO2 )6 , SIFSIX-3-Zn, and MOF-74 yield an interesting finding: the 2 H SSNMR spectra of methane adsorbed in these MOFs are significantly influenced by the chemical shielding anisotropy in addition to the quadrupolar interaction. The chemical shielding anisotropy contribution is likely due mainly to the nuclear independent chemical shift effect on the MOF surfaces. In addition, the 2 H SSNMR results and DFT calculations strongly indicate that the methane adsorption strength is linked to the MOF pore size and that dispersive forces are responsible for the methane adsorption in these systems. This work lays a very promising foundation for future studies of methane adsorption locations and dynamics within adsorbent MOF materials.

The Strong β-CF3 Shielding Effect in Hexafluoroisopropanol and 100 Other Organic Solvents Revisited with 17O NMR Spectroscopy.

An 17O NMR spectroscopy survey of more than 100 ubiquitous organic solvents and compounds, including some typical oxofluorinated solvents such as hexafluoroisopropanol, trifluoroethanol, trifluoroacetic acid, and others, is presented with D2O as a reference. A strong alternating α,β−CF3‐substituent chemical shift effect was thus observed. This alternating deshielding–shielding effect is suspected to have a role in the exceptional properties of these oxofluorinated solvents, notably in oxidative cross‐coupling reactions.

An experimental validation of a Bayesian model for quantification in NMR spectroscopy

The traditional peak integration method for quantitative analysis in nuclear magnetic resonance (NMR) spectroscopy is inherently limited by its ability to resolve overlapping peaks and is susceptible to noise. The alternative model-based approaches not only extend quantification capabilities to these challenging examples but also provide a means for automation of the entire process of NMR data analysis. In this paper, we present a general model for an NMR signal that, in a principled way, takes into account the effects of chemical shifts, relaxation, lineshape imperfections, phasing, and baseline distortions. We test the model using both simulations and experiments, concentrating on simple spectra with well-resolved peaks where we expect conventional analysis to be effective. Our results of quantifying mixture compositions compare favorably with the established methods. At high SNR (>40dB), all approaches usually achieve for these test systems an absolute accuracy of at least 0.01mol/mol for the concentrations of all species. Our model-based approach is successful even for SNR<20dB; it achieves 0.05–0.1mol/mol accuracy in cases where precise phasing is practically impossible due to high levels of noise in the data.

Calculation of 125Te NMR Chemical Shifts at the Full Four-Component Relativistic Level with Taking into Account Solvent and Vibrational Corrections: A Gateway to Better Agreement with Experiment.

Four-component relativistic calculations of 125Te NMR chemical shifts were performed in the series of 13 organotellurium compounds, potential precursors of the biologically active species, at the density functional theory level under the nonrelativistic and four-component fully relativistic conditions using locally dense basis set scheme derived from relativistic Dyall's basis sets. The relativistic effects in tellurium chemical shifts were found to be of as much as 20-25% of the total calculated values. The vibrational and solvent corrections to 125Te NMR chemical shifts are about, accordingly, 6 and 8% of their total values. The PBE0 exchange-correlation functional turned out to give the best agreement of calculated tellurium shifts with their experimental values giving the mean absolute percentage error of 4% in the range of ∼1000 ppm, provided all corrections are taken into account.

An allosteric site in the T-cell receptor C\u03b2 domain plays a critical signalling role

The molecular mechanism through which the interaction of a clonotypic αβ T-cell receptor (TCR) with a peptide-loaded major histocompatibility complex (p/MHC) leads to T-cell activation is not yet fully understood. Here we exploit a high-affinity TCR (B4.2.3) to examine the structural changes that accompany binding to its p/MHC ligand (P18-I10/H2-Dd). In addition to conformational changes in complementarity-determining regions (CDRs) of the TCR seen in comparison of unliganded and bound X-ray structures, NMR characterization of the TCR β-chain dynamics reveals significant chemical shift effects in sites removed from the MHC-binding site. Remodelling of electrostatic interactions near the Cβ H3 helix at the membrane-proximal face of the TCR, a region implicated in interactions with the CD3 co-receptor, suggests a possible role for an allosteric mechanism in TCR signalling. The contribution of these TCR residues to signal transduction is supported by mutagenesis and T-cell functional assays.

An allosteric site in the T cell receptor β-chain constant domain plays a critical role in T cell signaling

Abstract The molecular mechanism through which the interaction of a clonotypic αβ TCR with peptide/MHC (p/MHC) complexes leads to T cell activation is not yet fully understood. Here we exploit a high affinity TCR (B4.2.3) to examine the structural changes that accompany binding to its p/MHC ligand (P18-I10/H2-Dd) by combining crystallographic, NMR, and functional data. In addition to conformational changes in complementarity determining regions (CDR) of the TCR seen in comparison of unliganded and bound X-ray structures, NMR characterization of the TCR β chain dynamics reveals significant chemical shift effects in sites removed from the MHC binding site. In particular, a remodeling of electrostatic interactions near the Cβ H3 helix at the membrane-proximal face of the TCR, a region implicated in interactions with the CD3 co-receptor, suggests an allosteric mechanism for TCR signaling. The contribution of these TCR residues to signal transduction is supported by mutagenesis and T cell functional assays.

Ultrafast multi-slice spatiotemporally encoded MRI with slice-selective dimension segmented

As a recently emerging method, spatiotemporally encoded (SPEN) magnetic resonance imaging (MRI) has a high robustness to field inhomogeneity and chemical shift effect. It has been broadened from single-slice scanning to multi-slice scanning. In this paper, a novel multi-slice SPEN MRI method was proposed. In this method, the slice-selective dimension was segmented to lower the specific absorption rate (SAR) and improve the image quality. This segmented method, dubbed SeSPEN method, was theoretically analyzed and demonstrated with phantom, lemon and in vivo rat brain experiments. The experimental results were compared with the results obtained from the spin-echo EPI, spin-echo SPEN method and multi-slice global SPEN method proposed by Frydman and coauthors (abbr. GlSPEN method). All the SPEN images were super-resolved reconstructed using deconvolution method. The results indicate that the SeSPEN method retains the advantage of SPEN MRI with respect to resistance to field inhomogeneity and can provide better signal-to-noise ratio than multi-slice GlSPEN MRI technique. The SeSPEN method has comparable SAR to the GlSPEN method while the T1 signal attenuation effect is alleviated. The proposed method will facilitate the multi-slice SPEN MRI to scan more slices within one scan with better image quality.

A fast chemical exchange saturation transfer imaging scheme based on single-shot spatiotemporal encoding.

To design a new approach that can not only keep the spatial and temporal resolution but also have better built-in immunity to magnetic field inhomogeneity and chemical shift effects than the single-shot echo planar imaging (EPI) for chemical exchange saturation transfer (CEST) MRI. The single-shot spatiotemporally encoded (SPEN) MRI sequence was combined with a continuous wave saturation pulse for fast CEST MRI (CEST-SPEN MRI). The resulting images were super-resolved reconstructed by a hybrid method that solves the l1 norm minimization together with total variation (TV) regularization. Partial Lorentzian fitting was used to analyze the subsequent Z-spectra. Experimental results of a creatine phantom and in vivo tumor rat brains show that CEST-SPEN MRI has good capability in providing CEST-based and NOE-based contrast images. Compared with CEST-EPI, CEST-SPEN MRI has better immunity to magnetic field inhomogeneity and provides better contrast images within identical acquisition time, especially under an identical inhomogeneous field. Magn Reson Med 77:1786-1796, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

New N-[2-chloropropyl]-heterocyclohexanes. NMR long range shielding effects of chlorine substituent. Use of BH3 as freezing conformational agent

The syntheses of the new compounds: 5-(2-chloropropyl)-[1,3,5]-dithiazinane (1), 3,5-di-(2-chloropropyl)-[1,3,5]-thiadiazinane (2) and 1,3,5-tri-(2-chloropropyl)-[1,3,5]-triazinane (3) and their N-borane adducts 1(BH3), 2(BH3)2 and 3(BH3)2 are reported. The heterocyclohexanes are derived from the enantiomerically pure (S)-1-chloro-propylamine hydrochloride. NMR analyses in CD2Cl2 or TDF at rt indicate that heterocycles 1–3 are fluxional molecules whereas their corresponding borane adducts recorded in the same NMR conditions showed anchored conformations. The 1H spectrum of the N-borane adducts gave evidence that chlorine atoms produce γ and ε shielding electronic effects on protons. These effects have been rarely reported and only observed in rigid cyclic molecules. The 13C spectra showed another uncommon long range effect, a chlorine δ shielding effect. The preferred conformations that produced these chlorine chemical shift effects were determined with the aid of optimized conformers by using B3LYP/6-311 + G* density functional calculations and from data of X-ray diffraction analysis of compound 2. Compounds 1(BH3), 2(BH3)2 and 3(BH3)2 at room temperature in solution are slowly transformed into reduced products which are described.

Improved k-space-based MR thermometry by joint PRF phase shift and T1/T2* attenuation estimation

MR temperature mapping based on the proton resonance frequency (PRF) shift is used in MR-guided focused ultrasound procedures for dosimetry and safety monitoring. While conventional PRF-shift thermometry is based on calculating a phase difference between two reconstructed MR images, Gaur et al [1,2] have recently described two algorithms that estimate temperature-induced phase shifts directly from MR k-space data, prior to image reconstruction. The approach enables large dynamic scan acceleration factors[1] and the correction of chemical-shift (CS) effects that geometrically distort the temperature maps.[2] However, that work neglected image attenuation that accompanies the PRF phase shift and is primarily caused by increasing T1 with temperature.[3] Here it is shown that attenuation degrades the accuracy of k-space-based reconstructions, but that it can be accounted for in the reconstructions.

Super-resolved enhancing and edge deghosting (SEED) for spatiotemporally encoded single-shot MRI.

Spatiotemporally encoded (SPEN) single-shot MRI is an ultrafast MRI technique proposed recently, which utilizes quadratic rather than linear phase profile to extract the spatial information. Compared to the echo planar imaging (EPI), this technique has great advantages in resisting field inhomogeneity and chemical shift effects. Super-resolved (SR) reconstruction is adopted to compensate the inherent low resolution of SPEN images. Due to insufficient sampling rate, the SR image is challenged by aliasing artifacts and edge ghosts. The existing SR algorithms always compromise in spatial resolution to suppress these undesirable artifacts. In this paper, we proposed a novel SR algorithm termed super-resolved enhancing and edge deghosting (SEED). Different from artifacts suppression methods, our algorithm aims at exploiting the relationship between aliasing artifacts and real signal. Based on this relationship, the aliasing artifacts can be eliminated without spatial resolution loss. According to the trait of edge ghosts, finite differences and high-pass filter are employed to extract the prior knowledge of edge ghosts. By combining the prior knowledge with compressed sensing, our algorithm can efficiently reduce the edge ghosts. The robustness of SEED is demonstrated by experiments under various situations. The results indicate that the SEED can provide better spatial resolution compared to state-of-the-art SR reconstruction algorithms in SPEN MRI. Theoretical analysis and experimental results also show that the SR images reconstructed by SEED have better spatial resolution than the images obtained with conventional k-space encoding methods under similar experimental condition.

Intramolecular Halogen Bonding in Solution: 15N, 13C, and 19F NMR Studies of Temperature and Solvent Effects

AbstractA model system for the investigation of intramolecular halogen bonds is introduced. Two molecules capable of intramolecular halogen bonding have been studied in comparison with eight control compounds by 15N, 13C, and 19F NMR spectroscopy. Iodine‐ and bromine‐centered halogen bonds are indicated by decreases in the 15N NMR chemical shifts of the halogen bond acceptor atom of approximately 6 and 1 ppm, respectively. 13C NMR chemical shifts of the alkynyl carbons in 2‐ethynylpyridine systems are good indicators of halogen bonding, with differences of up to 2.4 ppm between halogen‐bonded and related control compounds. Halogen bond strengths in different solvents, as indicated by 19F NMR chemical shifts, decrease in the following order: Cyclohexane &gt; toluene &gt; benzene &gt; dichloromethane &gt; acetone &gt; pyridine. Chemical shift effects associated with the structural and electronic properties of intramolecular halogen‐bonded systems are modeled well by calculations at the B3LYP/6‐311+G(2d,p) level of theory.

R102Q mutation shifts the salt-bridge network and reduces the structural flexibility of human neuronal calcium sensor-1 protein.

Neuronal calcium sensor-1 (NCS-1) protein has a variety of different neuronal functions and interacts with multiple binding partners mostly through a large solvent-exposed hydrophobic crevice (HC). A single R102Q mutation in human NCS-1 protein was demonstrated to be associated with autism disease. Solution NMR study reported that this R102Q mutant had long-range chemical shift effects on the HC and the C-terminal tail (L3). To understand the influence of the R102Q mutation on the HC and L3 of NCS-1, we have investigated the conformational dynamics and the structural flexibility of wild type (WT) NCS-1 and its R102Q mutant by conducting extensive all-atom molecular dynamics (MD) simulations. On the basis of six independent 450 ns MD simulations, we have found that the R102Q mutation in NCS-1 protein (1) dramatically reduces the flexibility of loops L2 and L3, (2) facilitates L3 in a more extended state to occupy the hydrophobic crevice to a larger extent, (3) significantly affects the intersegment salt bridges, and (4) changes the subspace of the free energy landscape of NCS-1 protein. Analysis of the salt bridge network in both WT and the R102Q variant demonstrates that the R102Q-mutation-induced salt bridge alternations play a critical role on the reduced flexibility of L2 and L3. These results reveal the important role of salt bridges on the structural properties of NCS-1 protein and that R102Q mutation disables the dynamic relocation of C-terminus, which may block the binding of NCS-1 protein to its receptors. This study may provide structural insights into the autistic spectrum disorder associated with R102Q mutation.

Protein apparent dielectric constant and its temperature dependence from remote chemical shift effects.

A NMR protocol is introduced that permits accurate measurement of minute, remote chemical shift perturbations (CSPs), caused by a mutation-induced change in the electric field. Using protein GB3 as a model system, 1HN CSPs in K19A and K19E mutants can be fitted to small changes in the electric field at distal sites in the protein using the Buckingham equation, yielding an apparent dielectric constant εa of 8.6 ± 0.8 at 298 K. These CSPs, and their derived εa value, scale strongly with temperature. For example, CSPs at 313 K are about ∼30% smaller than those at 278 K, corresponding to an effective εa value of about 7.3 at 278 K and 10.5 at 313 K. Molecular dynamics simulations in explicit solvent indicate that solvent water makes a significant contribution to εa.

RNA recognition and self-association of CPEB4 is mediated by its tandem RRM domains.

Cytoplasmic polyadenylation is regulated by the interaction of the cytoplasmic polyadenylation element binding proteins (CPEB) with cytoplasmic polyadenylation element (CPE) containing mRNAs. The CPEB family comprises four paralogs, CPEB1–4, each composed of a variable N-terminal region, two RNA recognition motif (RRM) and a C-terminal ZZ-domain. We have characterized the RRM domains of CPEB4 and their binding properties using a combination of biochemical, biophysical and NMR techniques. Isothermal titration calorimetry, NMR and electrophoretic mobility shift assay experiments demonstrate that both the RRM domains are required for an optimal CPE interaction and the presence of either one or two adenosines in the two most commonly used consensus CPE motifs has little effect on the affinity of the interaction. Both the single RRM1 and the tandem RRM1–RRM2 have the ability to dimerize, although representing a minor population. Self-association does not affect the proteins’ ability to interact with RNA as demonstrated by ion mobility–mass spectrometry. Chemical shift effects measured by NMR of the apo forms of the RRM1–RRM2 samples indicate that the two domains are orientated toward each other. NMR titration experiments show that residues on the β-sheet surface on RRM1 and at the C-terminus of RRM2 are affected upon RNA binding. We propose a model of the CPEB4 RRM1–RRM2–CPE complex that illustrates the experimental data.

Structure‐guided design affirms inhibitors of hepatitis C virus p7 as a viable class of antivirals targeting virion release

Current interferon-based therapy for hepatitis C virus (HCV) infection is inadequate, prompting a shift toward combinations of direct-acting antivirals (DAA) with the first protease-targeted drugs licensed in 2012. Many compounds are in the pipeline yet primarily target only three viral proteins, namely, NS3/4A protease, NS5B polymerase, and NS5A. With concerns growing over resistance, broadening the repertoire for DAA targets is a major priority. Here we describe the complete structure of the HCV p7 protein as a monomeric hairpin, solved using a novel combination of chemical shift and nuclear Overhauser effect (NOE)-based methods. This represents atomic resolution information for a full-length virus-coded ion channel, or “viroporin,” whose essential functions represent a clinically proven class of antiviral target exploited previously for influenza A virus therapy. Specific drug-protein interactions validate an allosteric site on the channel periphery and its relevance is demonstrated by the selection of novel, structurally diverse inhibitory small molecules with nanomolar potency in culture. Hit compounds represent a 10,000-fold improvement over prototypes, suppress rimantadine resistance polymorphisms at submicromolar concentrations, and show activity against other HCV genotypes. Conclusion: This proof-of-principle that structure-guided design can lead to drug-like molecules affirms p7 as a much-needed new target in the burgeoning era of HCV DAA. (Hepatology 2014;59:408–422)

Design and Simulation of a Birdcage Coil using CST Studio Suite for Application at 7T

This work describes the study of coils for Magnetic Resonance Imaging (MRI) applications. The principal objective is the design of a birdcage Radio Frequency (RF) coil to use in a 7 Tesla (7T) scanner. Higher strength field generates a better SNR and increased chemical shift effect, improving spectral fat suppression and spectroscopy. Moreover, a better SNR increases the spatial resolution or reduces the imaging time. This research work presented recent developments based on high field 7T design using CST studio. The birdcage coil achieves circular polarization and generates a high homogeneous radio frequency magnetic field under many conditions. Design of a Birdcage coil for a 7T to obtain the images from s mall animals (i.e. mouse). It opens the door to design and construct a Birdcage coil for a 7T to obtain human brain images. Firstly we design a birdcage coil then the results are obtained with simulator CST Wave Studio, creating a 3D model and generating a simulation. Finally the parameters are re adjusted to obtain our desired Larmor frequency 298.2 MHz for a correct operation in 7T. This research work demonstrates the theoretical results from our design and shows the designed antenna behavior.

Examination of anticipated chemical shift and shape distortion effect on materials commonly used in prosthetic socket fabrication when measured using MRI: A validation study

The quality of lower-limb prosthetic socket fit is influenced by shape and volume consistency during the residual limb shape-capturing process (i.e., casting). Casting can be quantified with magnetic resonance imaging (MRI) technology. However, chemical shift artifact and image distortion may influence the accuracy of MRI when common socket/casting materials are used. We used a purpose-designed rig to examine seven different materials commonly used in socket fabrication during exposure to MRI. The rig incorporated glass marker tubes filled with water doped with 1 g/L copper sulfate (CS) and 9 plastic sample vials (film containers) to hold the specific material specimens. The specimens were scanned 9 times in different configurations. The absolute mean difference of the glass marker tube length was 1.39 mm (2.98%) (minimum = 0.13 mm [0.30%], maximum = 5.47 mm [14.03%], standard deviation = 0.89 mm). The absolute shift for all materials was <1.7 mm. This was less than the measurement tolerance of +/-2.18 mm based on voxel (three-dimensional pixel) dimensions. The results show that MRI is an accurate and repeatable method for dimensional measurement when using matter containing water. Additionally, silicone and plaster of paris plus 1 g/L CS do not show a significant shape distortion nor do they interfere with the MRI image of the residual limb.

Assessment of Fiducial-based 2D kV Orthogonal Imaging, Fiducial-based CBCT, and Soft-tissue-based CBCT for Prostate Cancer Patients With Implanted Fiducial Markers

Purpose/Objective(s): To assess the geometric accuracy and imaging performance of a newly developed phased array coil system optimized for MR imaging of patients immobilized with the type S frame for head and neck radiation therapy. Materials/Methods: Protocol optimization for the novel coil was undertaken using a GE Optima450-GEM 70cm wide bore unit adapted for radiation therapy MR-SIM localization. Pulse sequence parameters for T1FSE, T2 FRFSE and T1 and T2 CUBE (including matrix, slice thickness, bandwidth) were optimized to maximize SNR while minimizing the effect of chemical shift. Phantom measurements were then performed to quantify system related residual geometric distortions after application of a 3D commercial gradient distortion correction algorithm for the effective FOV and the pulse sequences utilized. The optimized protocols were used to image seven volunteers positioned using an MR compatible type S system with neutral head supports. MRI images (from the base of brain to below the clavicles) were acquired using the novel phased array coil combination placed over the head, neck and thoracic region. The volunteers were re-imaged without immobilization in a standard diagnostic head coil, which served as the benchmark for image quality. Signal to noise, image homogeneity and image artifacts were compared between the two image datasets in a blinded study. Visibility of ten anatomical structures was evaluated. For statistical analysis, Cohen’s kappa, Wilcoxon matched pairs and t-testing were utilized. Results: A geometrically accurate, high resolution MR-SIM imaging protocol (T1/T2CUBE. 2D T1/T2 FSE) was developed with 3mm slice thickness/no gap that provides excellent image quality from the base of brain to below the clavicles in the treatment position. From phantom studies, residual distortions were found to be 1.0mm within a 10 cm radius and < 1.5 mm within a 15 cm radius of the scan centre. Using a RBWof 50-62.5 minimized chemical shift (<1mm within a 10cm radius) at 1.5T while providing acceptable SNR. The coil provided higher SNR values in all anatomical structures, but less uniformity than the standard diagnostic head coil (full comparative SNR/CNR/geometric data will be presented). No significant difference for image quality and artifacts were demonstrated between the coils in the blinded study. Conclusions: The novel open architecture purpose built phased coil array provides unparalleled coverage and good image quality of the subject immobilized for head and neck radiation therapy and is a promising solution for MR-SIM in the head and neck region. Author Disclosure: G. Perkins: None. R. Hammoud: None. S. Pienaar: None. S. Paloor: None. N. Al Hammadi: None.