Spine Array Research Articles

A new species of Neoergasilus Yin 1956 (Copepoda: Cyclopoida: Ergasilidae) parasitic on the catfish Clarias gariepinus (Burchell, 1822) (Siluriformes: Clariidae) from South Africa

Twenty-one specimens of an ergasilid were collected from the gills of the sharptooth catfish, Clarias gariepinus (Burchell), from the Eastern Cape, South Africa. The first leg and antennae morphology conformed to the genus Neoergasilus Yin, 1956. While the invasive Neoergasilus japonicus (Harada, 1930) is the only Neoergasilus species that has been reported from Africa, the combination of several characteristics, separates the Eastern Cape specimens from N. japonicus and the other eight Neoergasilus congeners. These include an inflated cephalothorax; the presence of an oval dorsal ornamentation anterior to the cephalosome; a spine on the posterodistal margin of the first antennal segment; a cone-like process at the proximal margin of the second antennal segment; a knob-like process on the inner distal margin of the first exopodal segment of leg 1 and two forked spines on the third exopodal segment; leg 4 bearing a 2-segmented exopod and 3-segmented endopod; a single-segmented fifth leg with a seta extending from the base of the pedigerous somite and three unequal setae on its free segment; and a median caudal rami seta with an array of spines. Supporting genetic data were generated using two partial ribosomal RNA genes, 18S and 28S, and one partial mitochondrial DNA gene, COI. The Eastern Cape species is here proposed as new to science and described as Neoergasilus africanusn. sp. (Ergasilidae: Cyclopoida). This is the first Neoergasilus species described from the sharptooth catfish and from the southern hemisphere. Additionally, a key to all the species of this genus is provided.

Dual Biomimetic Synergistic Effects of Cactus Spines and Desert Beetle Shells for Water-In-Oil Emulsion Separation.

Drawing inspiration from the unique properties of cactus spines and desert beetle shells, we have designed a biomimetic stainless steel mesh specifically for efficient water-in-oil emulsion separation. The tapered arrays of cactus spines are prepared by a light-curing-templating method, and the hydrophobic regions are constructed by adhering hydrophobic silica nanoparticles to the surface of the mesh. This innovative design takes full advantage of the unique properties of these two natural plants, which can agglomerate tiny emulsified water to achieve an emulsion-breaking effect only under static conditions. At the same time, the stainless steel mesh with the conical arrays has a high water-in-oil emulsion separation efficiency (up to 99.6%), high permeance (2400 L·m-2·h-1·bar-1), and good cycling performance. The concept of dual biomimetic explored in this work may extend beyond oil-water separation to encompass various applications, such as fog collection, droplet manipulation, and more.

Feasibility of Accelerated Prostate Diffusion-Weighted Imaging on 0.55 T MRI Enabled With Random Matrix Theory Denoising.

Prostate cancer diffusion weighted imaging (DWI) MRI is typically performed at high-field strength (3.0 T) in order to overcome low signal-to-noise ratio (SNR). In this study, we demonstrate the feasibility of prostate DWI at low field enabled by random matrix theory (RMT)-based denoising, relying on the MP-PCA algorithm applied during image reconstruction from multiple coils. Twenty-one volunteers and 2 prostate cancer patients were imaged with a 6-channel pelvic surface array coil and an 18-channel spine array on a prototype 0.55 T system created by ramping down a commercial magnetic resonance imaging system (1.5 T MAGNETOM Aera Siemens Healthcare) with 45 mT/m gradients and 200 T/m/s slew rate. Diffusion-weighted images were acquired with 4 non-collinear directions, for which b = 50 s/mm 2 was used with 8 averages and b = 1000 s/mm 2 with 40 averages; 2 extra b = 50 s/mm 2 were used as part of the dynamic field correction. Standard and RMT-based reconstructions were applied on DWI over different ranges of averages. Accuracy/precision was evaluated using the apparent diffusion coefficient (ADC), and image quality was evaluated over 5 separate reconstructions by 3 radiologists with a 5-point Likert scale. For the 2 patients, we compare image quality and lesion visibility of the RMT reconstruction versus the standard one on 0.55 T and on clinical 3.0 T. The RMT-based reconstruction in this study reduces the noise floor by a factor of 5.8, thereby alleviating the bias on prostate ADC. Moreover, the precision of the ADC in prostate tissue after RMT increases over a range of 30%-130%, with the increase in both signal-to-noise ratio and precision being more prominent for a low number of averages. Raters found that the images were consistently of moderate to good overall quality (3-4 on the Likert scale). Moreover, they determined that b = 1000 s/mm 2 images from a 1:55-minute scan with the RMT-based reconstruction were on par with the corresponding images from a 14:20-minute scan with standard reconstruction. Prostate cancer was visible on ADC and calculated b = 1500 images even with the abbreviated 1:55-minute scan reconstructed with RMT. Prostate imaging using DWI is feasible at low field and can be performed more rapidly with noninferior image quality compared with standard reconstruction.

A genetic labeling system to study dendritic spine development in zebrafish models of neurodevelopmental disorders.

ABSTRACTDendritic spines are the principal site of excitatory synapse formation in the human brain. Several neurodevelopmental disorders cause spines to develop abnormally, resulting in altered spine number and morphology. Although spine development has been thoroughly characterized in the mammalian brain, spines are not unique to mammals. We have developed a genetic system in zebrafish to enable high-resolution in vivo imaging of spine dynamics during larval development. Although spiny neurons are rare in the larval zebrafish, pyramidal neurons (PyrNs) of the zebrafish tectum form an apical dendrite containing a dense array of dendritic spines. To characterize dendritic spine development, we performed mosaic genetic labeling of individual PyrNs labeled by an id2b:gal4 transgene. Our findings identify a developmental period during which PyrN dendrite growth is concurrent with spine formation. Throughout this period, motile, transient filopodia gradually transform into stable spines containing postsynaptic specializations. The utility of this system to study neurodevelopmental disorders was validated by examining spine development in fmr1 mutant zebrafish, a model of fragile X syndrome. PyrNs in fmr1 mutants exhibited pronounced defects in dendrite growth and spine stabilization. Taken together, these findings establish a genetic labeling system to study dendritic spine development in larval zebrafish. In the future, this system could be combined with high-throughput screening approaches to identify genes and drug targets that regulate spine formation.

Clinical Feasibility of Structural and Functional MRI in Free‐Breathing Neonates and Infants

Evaluation of structural lung abnormalities with magnetic resonance imaging (MRI) has previously been shown to be predictive of clinical neonatal outcomes in preterm birth. MRI during free-breathing with phase-resolved functional lung (PREFUL) may allow for complimentary functional information without exogenous contrast. To investigate the feasibility of structural and functional pulmonary MRI in a cohort of neonates and infants with no cardiorespiratory disease. Macrovascular pulmonary blood flows were also evaluated. Prospective. Ten term infants with no clinically defined cardiorespiratory disease were imaged. Infants recruited from the general population and neonatal intensive care unit (NICU) were studied. T1 -weighted VIBE, T2 -weighted BLADE uncorrected for motion. Ultrashort echo time (UTE) and 3D-flow data were acquired during free-breathing with self-navigation and retrospective reconstruction. Single slice 2D-gradient echo (GRE) images were acquired during free-breathing for PREFUL analysis. Imaging was performed at 3T. T1 , T2 , and UTE images were scored according to the modified Ochiai scheme by three pediatric body radiologists. Ventilation/perfusion-weighted maps were extracted from free-breathing GRE images using PREFUL analysis. Ventilation and perfusion defect percent (VDP, QDP) were calculated from the segmented ventilation and perfusion-weighted maps. Time-averaged cardiac blood velocities from three-dimensional-flow were evaluated in major pulmonary arteries and veins. Intraclass correlation coefficient (ICC). The ICC of replicate structural scores was 0.81 (95% CI: 0.45-0.95) across three observers. Elevated Ochiai scores, VDP, and QDP were observed in two NICU participants. Excluding these participants, mean ± standard deviation structural scores were 1.2 ± 0.8, while VDP and QDP were 1.0% ± 1.1% and 0.4% ± 0.5%, respectively. Main pulmonary arterial blood flows normalized to body surface area were 3.15 ± 0.78 L/min/m2 . Structural and functional pulmonary imaging is feasible using standard clinical MRI hardware (commercial whole-body 3T scanner, table spine array, and flexible thoracic array) in free-breathing infants. 2 TECHNICAL EFFICACY: Stage 1.

An endovaginal MRI array with a forward-looking coil for advanced gynecological cancer brachytherapy procedures: Design and initial results.

To develop an endovaginal MRI array that provides signal enhancement forward into the posterior parametrium and sideways into the vaginal wall, accelerating multiple-contrast detection of residual tumors that survive external beam radiation. The array's enclosure should form an obturator for cervical cancer brachytherapy, allowing integration with MRI-guided catheter placement, CT, and interstitial radiation dose delivery. The endovaginal array consisted of forward-looking and sideways-looking components. The forward-looking element imaged the cervix and posterior endometrium, and the sideways-looking elements imaged the vaginal wall. Electromagnetic simulation was performed to optimize the geometry of a forward-looking coil placed on a conductive-metallic substrate, extending the forward penetration above the coil's tip. Thereafter, an endovaginal array with one forward-looking coil and four sideways-looking elements was constructed and tested at 1.5 Tesla in saline and gel phantoms, and three sexually mature swine. Each coil's tuning, matching, and decoupling were optimized theoretically, implemented with electronic circuits, and validated with network-analyzer measurements. The array enclosure emulates a conventional brachytherapy obturator, allowing use of the internal imaging array together with tandem coils and interstitial catheters, as well as use of the enclosure alone during CT and radiation delivery. To evaluate the receive magnetic field ( ) spatial profile, the endovaginal array's specific absorption-rate (SAR) distribution was simulated inside a gel ASTM phantom to determine extreme heating locations in advance of a heating test. Heating tests were then performed during high SAR imaging in a gel phantom at the predetermined locations, testing compliance with MRI safety standards. To assess array imaging performance, signal-to-noise-ratios (SNR) were calculated in a saline phantom and in vivo. Swine images were acquired with the endovaginal array combined with the scanner's body and spine arrays. Simulated profiles for the forward-looking lobe pattern, obtained while varying several geometric parameters, disclosed that a forward-looking coil placed on a metal-backed substrate could double the effective forward penetration from approximately 25 to ∼40mm. An endovaginal array, enclosed in an obturator enclosure was then constructed, with all coils tuned, matched, and decoupled. The ASTM gel-phantom SAR test showed that peak local SAR was 1.2 W/kg in the forward-looking coil and 0.3 W/kg in the sideways-looking elements, well within ASTM/FDA/IEC guidelines. A 15-min 4 W/kg average SAR imaging experiment resulted inless than2o C temperature increase, also within ASTM/FDA/IEC heating limits. In a saline phantom, the forward-looking coil and sideways-looking array's SNR was four to eight times, over a 20-30mm field-of-view (FOV), and five to eight times, over a 15-25mm FOV, relative to the spine array's SNR, respectively. In three sexually mature swine, the forward-looking coil provided a 5+0.2 SNR enhancement factor within the cervix and posterior endometrium, and the sideways-looking array provided a 4+0.2 SNR gain factor in the vaginal wall, relative to the Siemens spine array, demonstrating that the array could significantly reduce imaging time. Higher SNR gynecological imaging is supported by forward-looking and sideways-looking coils. A forward-looking endovaginal coil for cervix and parametrium imaging was built with optimized metal backing. Array placement within an obturator enhanced integration with the brachytherapy procedure and accelerated imaging for detecting postexternal-beam residual tumors.

Technical Note: A custom-designed flexible MR coil array for spine radiotherapy treatment planning.

To assess the performance and optimize the MR image quality when using a custom-built flexible radiofrequency (RF) spine coil array fitted between the immobilization device and the patient for spine radiotherapy treatment planning. A 32 channel flexible custom-designed receive-only coil array has been developed for spine radiotherapy simulation for a 3T Philips MR scanner. Coil signal-to-noise performance and interactions with standard vendor hardware were assessed. In four volunteers, immobilization molds were created with a dummy version of the array within the mold, and subjects were scanned using the custom array in the mold. Phantoms and normal volunteers were scanned with both the custom spine coil array and the vendor's FDA-approved in-table posterior coil array to compare performance. The superior-inferior field of view for the custom spine array was ~30cm encompassing at least 10 vertebrae. A noise correlation matrix showed at least 25dB isolation between all coil elements. Signal-to-noise ratio (SNR) calculated on a phantom scan at the depth of the spinal cord was a factor of 3 higher with the form-fit spine array as compared to the vendor's posterior coil array. The body coil B1 transmit map was equivalent with and without the spine array in place demonstrating that the elements are decoupled from the body coil. Volunteer imaging showed improved SNR as compared to the vendor's posterior coil array. The custom array permitted a high degree of acceleration making possible the acquisition of isotropic high-resolution 1.1×1.1×1.1mm3 three-dimensional data set over a 30-cm section of the spine in less than 5min. The custom-designed form-fitting flexible spine coil array provided enhanced SNR and increased acceleration compared to the vendor's posterior array. Future studies will assess MR-based spinal cord imaging with the custom coil in comparison to CT myelogram.

Gender interactions between vertebral bone mineral density and fat content in the elderly: Assessment using fat-water MRI.

Adipose tissue is closely related to bone mass, bone quality, and bone fractures, but the connection between fat and bone is complex and gender-related. Fat-water magnetic resonance imaging (MRI) and MR spectroscopy (MRS) are very useful tools for identifying tissue fat. To assess gender interactions between bone mineral density (BMD), bone marrow fat, and body mass index (BMI) in the elderly using fat-water MRI and MRS. Prospective/cohort. Sixty-six women and 38 men (mean age, 62.3 years; range, 50-75 years), Asian. A 1.5T MR equipped with a body and spine array coil. STEAM MRS and T2 * Dixon were performed. Vertebral bone marrow fat ratio (MFR), BMI, and BMD were measured. Correlations between these variables and differences in bone density in MFR were assessed between participants, divided into three groups based on bone density. Multiple regression; Pearson tests; analysis of covariance; analysis of variance. Multiple regression analysis identified gender, vertebral bone MFR, and BMI as significant predictors of vertebral BMD (P < 0.001). Among the women, vertebral BMD was negatively correlated with vertebral MFR (P = 0.011), but among the men, it was positively correlated with BMI (P = 0.048), although this relationship was confounded by age and MFR. Moreover, vertebral bone marrow fat and BMI were indeed statistically uncorrelated in the elderly (P = 0.357 in women; P = 0.961 in men). We found gender interactions between fat and bone in the elderly. Higher bone marrow fat was correlated with lower trabecular BMD in older women but not in men. On the other hand, the positive correlation between BMI and BMD was more pronounced in men than in women. 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1382-1389.

SpinyHand: Contact Load Sharing for a Human-Scale Climbing Robot

We present a hand specialized for climbing unstructured rocky surfaces. Articulated fingers achieve grasps commonly used by human climbers. The gripping surfaces are equipped with dense arrays of spines that engage with asperities on hard rough materials. A load-sharing transmission system divides the shear contact force among spine tiles on each phalanx to prevent premature spine slippage or grasp failure. Taking advantage of the hand’s kinematic and load-sharing properties, the wrench space of achievable forces and moments can be computed rapidly. Bench-top tests show agreement with the model, with average wrench space errors of 10–15%, despite the stochastic nature of spine/surface interaction. The model provides design guidelines and control strategy insights for the SpinyHand and can inform future work.

Diffuse myocardial fibrosis in adolescents operated with arterial switch for transposition of the great arteries - A CMR study

Diffuse myocardial fibrosis in adolescents operated with arterial switch for transposition of the great arteries - A CMR study

A revised ontogeny of the early Ordovician trilobite Leptoplastides salteri (Callaway, 1877)

ABSTRACTThe ontogeny of the pelturine olenid trilobite Leptoplastides salteri (Callaway, 1877) from the Shineton Shales, Shropshire, England, was first described in 1925 by Frank Raw. Since that time, scanning electron microscopy and other new technologies have revealed many more details of structure, of early developmental stages in particular, than were available to Raw. Whereas protaspides are not preserved and the state of preservation is less than perfect for the smallest meraspides, we have established that the latter had an array of delicate, long thoracic and pygidial spines, as well as paired procranidial spines, which disappear by meraspid degree 8. Raw's reconstructions of early meraspides, and his measurements of the early stages in development, are here amended in the light of new information. Dorsal spines in the adult are much more highly developed than have been documented in any other olenid. The hypostome is preserved in place in several specimens. Initially conterminant (attached to the doublure), it becomes natant (free) in late meraspid to early holaspid stages of development, with its anterior contour fitting exactly to that of the glabella. The ecology of the widespread Leptoplastides is best known from very extensive sections in South America, which provide a useful basis for comparison. It was well adapted to a range of environments, both oxygenated and dysoxic, and is usually the dominant taxon in the biofacies in which it is found.

Stochastic models of compliant spine arrays for rough surface grasping

This paper presents models of arrays of compliantly supported spines that attach to rough surfaces. The applications include climbing and perching robots. Surfaces are characterized in terms of asperity distributions, which lead to stochastic models of spine force capabilities over a range of loading directions. Models cover unidirectional spine arrays and pairs of opposed arrays that withstand normal forces pulling away from a surface. Experiments on a variety of surfaces confirm the predicted behavior. For opposed spine arrays, the overall load capability also depends on the preloading strategy for applying internal forces. Insights from the analysis guide the design of spine array mechanisms to allow, for example, a small aerial platform to attach to walls and ceilings.

Arterial spin labeling MRI is able to detect early hemodynamic changes in diabetic nephropathy.

To investigate whether arterial spin labeling (ASL) MRI could detect renal hemodynamic impairment in diabetes mellitus (DM) along different stages of chronic kidney disease (CKD). Three Tesla (3T) ASL-MRI was performed to evaluate renal blood flow (RBF) in 91 subjects (46 healthy volunteers and 45 type 2 diabetic patients). Patients were classified according to their estimated glomerular filtration rate (eGFR) as group I (eGFR > 60 mL/min/1.73 m2 ), group II (60 ≥ eGFR>30 mL/min/1.73 m2 ), or group III (eGFR ≤ 30 mL/min/1.73 m2 ), to determine differences depending on renal function. Studies were performed at 3T using a 12-channel flexible body array combined with the spine array coil as receiver. A 28% reduction in cortical RBF was seen in diabetics in comparison with healthy controls (185.79 [54.60] versus 258.83 [37.96] mL/min/100 g, P < 3 × 10-6 ). Differences were also seen between controls and diabetic patients despite normal eGFR and absence of overt albuminuria (RBF [mL/min/100 g]: controls=258.83 [37.96], group I=208.89 [58.83], P = 0.0018; eGFR [mL/min/1.73 m2 ]: controls = 95.50 [12.60], group I = 82.00 [20.76], P > 0.05; albumin-creatinine ratio [mg/g]: controls = 3.50 [4.45], group I = 17.50 [21.20], P > 0.05). A marked decrease in RBF was noted a long with progression of diabetic nephropathy (DN) through the five stages of CKD (χ2 = 43.58; P = 1.85 × 10-9 ). Strong correlation (r = 0.62; P = 4 × 10-10 ) was obtained between RBF and GFR estimated by cystatin C. ASL-MRI is able to quantify early renal perfusion impairment in DM, as well as changes according to different CKD stages of DN. In addition, we demonstrated a correlation of RBF quantified by ASL and GFR estimated by cystatin C. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1810-1817.

Pectoral Morphology inDoliodus: Bridging the ‘Acanthodian’-Chondrichthyan Divide

ABSTRACT Doliodus problematicus (NBMG 10127), from the Lower Devonian of New Brunswick, Canada (approx. 397–400 Mya) is the earliest sharklike jawed vertebrate (gnathostome) in which the pectoral girdle and fins are well preserved. Its pectoral endoskeleton included sharklike expanded paired coracoids, but Doliodus also possessed an “acanthodian-like” array of dermal spines, described here for the first time. Doliodus provides the strongest anatomical evidence to date that chondrichthyans arose from “acanthodian” fishes by exhibiting an anatomical mosaic of “acanthodian” and sharklike features.

Eight‐channel decoupled array for cervical spinal cord imaging at 3T: six‐channel posterior and two‐channel anterior array coil

AbstractThe purpose of this study was to develop a dedicated high signal‐to‐noise ratio (SNR) radio frequency coil for cervical spinal cord (CSC) imaging without using the preamp decoupling technique. A novel eight‐channel CSC array was constructed using butterfly, loop (circular), and rectangular elements. The adjacent elements were decoupled by the critical geometrical overlapping, and most non‐adjacent elements were decoupled using the loop and butterfly elements. The performance of the proposed CSC coil was compared with the performance of the standard manufacturer's coil (Siemens' head, neck, and spine array) at 3T MRI system in T2‐weighted images, diffusion tensor images, and ultrahigh‐b diffusion‐weighted images. In T2‐weighted images, the SNR improvement of the eight‐channel CSC coil was 1.4–2.0 times over the manufacturer's coil at the different levels of the CSC vertebrae. Higher contrast between white matter and gray matter was observed in the diffusion‐weighted (b = 500 s/mm2) images and the fractional anisotropy maps obtained using the eight‐channel CSC coil compared with the manufacturer's coil. The eight‐channel CSC coil yielded 2.0 times higher SNR compared with the manufacturer's coil from the white matter region of the ultrahigh‐b (b = 7348 s/mm2) radial diffusion‐weighted images.

A 7T spine array based on electric dipole transmitters.

The goal of this study was to explore the feasibility of using an array of electric dipole antennas for RF transmission in spine MRI at high fields. A two-channel transmit array based on an electric dipole design was quantitatively optimized for 7T spine imaging and integrated with a receive array combining eight loop coils. Using B1+ mapping, the transmit efficiency of the dipole array was compared with a design using quadrature loop pairs. The radiofrequency energy deposition for each array was measured using a home-built dielectric phantom and MR thermometry. The performance of the proposed array was qualitatively demonstrated in human studies. The results indicate dramatically improved transmit efficiency for the dipole design compared with the loop excitation. A gain of up to 76% was achieved within the spinal region. For imaging of the spine, electric dipole-based transmitters provide an attractive alternative to the traditional loop-based design. Easy integration with existing receive array technology facilitates practical use at high fields.

Sodium-23 MRI of whole spine at 3 Tesla using a 5-channel receive-only phased-array and a whole-body transmit resonator

Sodium magnetic resonance imaging (23Na MRI) is a unique and non-invasive imaging technique which provides important information on cellular level about the tissue of the human body. Several applications for 23Na MRI were investigated with regard to the examination of the tissue viability and functionality for example in the brain, the heart or the breast. The 23Na MRI technique can also be integrated as a potential monitoring instrument after radiotherapy or chemotherapy. The main contribution in this work was the adaptation of 23Na MRI for spine imaging, which can provide essential information on the integrity of the intervertebral disks with respect to the early detection of disk degeneration.In this work, a transmit-only receive-only dual resonator system was designed and developed to cover the whole human spine using 23Na MRI and increase the receive sensitivity. The resonator system consisted of an already presented 23Na whole-body resonator and a newly developed 5-channel receive-only phased-array. The resonator system was first validated using bench top and phantom measurements. A threefold SNR improvement at the depth of the spine (∼7cm) over the whole-body resonator was achieved using the spine array. 23Na MR measurements of the human spine using the transmit-only receive-only resonator system were performed on a healthy volunteer within an acquisition time of 10minutes. A density adapted 3D radial sequence was chosen with 6mm isotropic resolution, 49ms repetition time and a short echo time of 540μs. Furthermore, it was possible to quantify the tissue sodium concentration in the intervertebral discs in the lumbar region (120ms repetition time) using this setup.

A Wheeled Wall-Climbing Robot with Bio-Inspired Spine Mechanisms

This paper presents a wheeled wall-climbing robot with the ability to climb concrete, brick walls using circular arrays of miniature spines located around the wheel. The robot consists of two driving wheels and a flexible tail, just like letter “T”, so it is called Tbot. The simple and effective structure of Tbot enables it to be steerable and to transition from horizontal to vertical surfaces rapidly and stably. Inspired by the structure and mechanics of the tarsal chain in the Serica orientalis Motschulsky, a compliant spine mechanism was developed. With the bio-inspired compliant spine mechanism, the climbing performance of Tbot was improved. It could climb on 100° (10° past vertical) brick walls at a speed of 10 cm·s−1. A mechanical model is also presented to analyze the forces acting on spine during a climbing cycle as well as load share between multi-spines. The simulation and experiment results show that the mechanical model is suitable and useful in the optimum design of Tbot.

GS0108-337 脊椎インプラントのコネクタによる延長時の応力解析

Scoliosis is a disease in which the spine is curved to the lateral. Surgery is the only way to revert from serious scoliosis to normal spinal array. Metallic implant is used in scoliosis surgery to correct the spine array. The spinal implant is composed of a plurality of components such as rod, connector and screw. However, the implant installed would be sometimes broken in everyday life. In this study, the implant model is recreated in the CAD system, to perform stress analysis by the finite element method. It is clarified that the absolute value of the longitudinal compressive stress increases at the edge portion of the slit of the connector and the tensile stress increases at the central portion of the connector side closer to the vertebra.

Radio-frequency coil selection for MR imaging of the carotid vessel wall

This aim of this study was to identify the radiofrequency coil that will produce optimum image quality for scanning the carotid vessel wall using magnetic resonance imaging. A comparative cross-sectional study was conducted using 10 volunteers. Each volunteer was scanned three times using a 1.5T Signa HDxt machine equipped with one of three different coils: a neurovascular array (NV) coil, an 8-channel CTL spine array coil, and a 3-inch surface coil. A qualitative image quality rating was assigned to each image. The images were also evaluated by measuring the signal to noise ratio (SNR) using Osirix 4.2.3 software. The noise was estimated from the mean intensities of the region of interest in the background of the images and the signal was measured in the muscle adjacent to the vessel wall. The SNRs of the three coils were compared using one-way ANOVA, with 104 images used for the data analysis. The mean image quality scores for the NV head coil, CTL coil, and 3-inch coil were 3.4, 3.33, and 1.67, respectively. In addition, the SNRs differed significantly (p < 0.05). The mean SNR for the 3-inch coil was significantly higher (56.21 ± 25.06) than those for the NV head coil (27.34 ± 15.47) and CTL coil (21.77 ± 13.14). The Bonferroni post-hoc test revealed that there was no significant difference between the NV head coil and the CTL coil (p = 0.21). The optimum SNR value was 20-27. These results indicate that the NV head coil and CTL coil can be used to evaluate the carotid arterial wall with optimum image quality and higher resolution. These coil can deliver fast and robust data to image the carotid vessel wall in vivo.