Needle Axis Research Articles

Deep learning-based automatic pipeline for 3D needle localization on intra-procedural 3D MRI.

Accurate and rapid needle localization on 3D magnetic resonance imaging (MRI) is critical for MRI-guided percutaneous interventions. The current workflow requires manual needle localization on 3D MRI, which is time-consuming and cumbersome. Automatic methods using 2D deep learning networks for needle segmentation require manual image plane localization, while 3D networks are challenged by the need for sufficient training datasets. This work aimed to develop an automatic deep learning-based pipeline for accurate and rapid 3D needle localization on in vivo intra-procedural 3D MRI using a limited training dataset. The proposed automatic pipeline adopted Shifted Window (Swin) Transformers and employed a coarse-to-fine segmentation strategy: (1) initial 3D needle feature segmentation with 3D Swin UNEt TRansfomer (UNETR); (2) generation of a 2D reformatted image containing the needle feature; (3) fine 2D needle feature segmentation with 2D Swin Transformer and calculation of 3D needle tip position and axis orientation. Pre-training and data augmentation were performed to improve network training. The pipeline was evaluated via cross-validation with 49 in vivo intra-procedural 3D MR images from preclinical pig experiments. The needle tip and axis localization errors were compared with human intra-reader variation using the Wilcoxon signed rank test, with p < 0.05 considered significant. The average end-to-end computational time for the pipeline was 6s per 3D volume. The median Dice scores of the 3D Swin UNETR and 2D Swin Transformer in the pipeline were 0.80 and 0.93, respectively. The median 3D needle tip and axis localization errors were 1.48mm (1.09 pixels) and 0.98°, respectively. Needle tip localization errors were significantly smaller than human intra-reader variation (median 1.70mm; p < 0.01). The proposed automatic pipeline achieved rapid pixel-level 3D needle localization on intra-procedural 3D MRI without requiring a large 3D training dataset and has the potential to assist MRI-guided percutaneous interventions.

Comparison of a Patient-Mounted Needle-Driving Robotic System versus Single-Rotation CT Fluoroscopy to Perform CT-Guided Percutaneous Lung Biopsies

PurposeTo compare the effectiveness of percutaneous lung biopsy using a patient-mounted needle-driving robotic system with that using a manual insertion of needles under computed tomography (CT) fluoroscopy guidance. Materials and MethodsIn this institutional review board approved study, the cohort consisted of a series of patients who underwent lung biopsies following the intention-to-treat protocol from September 2022 to September 2023 using robot (n = 15) or manual insertion under single-rotation CT fluoroscopy (n = 66). Patient and procedure characteristics were recorded as well as outcomes. ResultsAlthough age, body mass index, and skin-to-target distance were not statistically different, target size varied (median, 8 mm [interquartile range, 6.5–9.5 mm] for robot vs 12 mm [8–18 mm] for single-rotation CT fluoroscopy; P = .001). No statistical differences were observed in technical success (86.7% [13/15] vs 89.4% [59/66], P = .673), Grade 3 adverse event (AE) (6.7% [1/15] vs 12.1% [8/66], P = .298), procedural time (28 minutes [22–32 minutes] vs 19 minutes [14.3–30.5 minutes], P = .086), and patient radiation dose (3.9 mSv [3.2–5.6 mSv] vs 4.6 mSv [3.3–7.5 mSv], P = .398). In robot-assisted cases, the median angle out of gantry plane was 10° (6.5°–16°), although it was null (0°–5°) for single-rotation CT fluoroscopy (P = .001). ConclusionsRobot-assisted and single-rotation CT fluoroscopy–guided percutaneous lung biopsies were similar in terms of technical success, diagnostic yield, procedural time, AEs, and radiation dose, although robot allowed for out-of-gantry plane navigation along the needle axis.

Moderate Signal Enhancement in Electrospray Ionization Mass Spectrometry by Focusing Electrospray Plume with a Dielectric Layer around the Mass Spectrometer's Orifice.

Electrospray ionization (ESI) is among the commonly used atmospheric pressure ionization techniques in mass spectrometry (MS). One of the drawbacks of ESI is the formation of divergent plumes composed of polydisperse microdroplets, which lead to low transmission efficiency. Here, we propose a new method to potentially improve the transmission efficiency of ESI, which does not require additional electrical components and complex interface modification. A dielectric plate-made of ceramic-was used in place of a regular metallic sampling cone. Due to the charge accumulation on the dielectric surface, the dielectric layer around the MS orifice distorts the electric field, focusing the charged electrospray cloud towards the MS inlet. The concept was first verified using charge measurement on the dielectric material surface and computational simulation; then, online experiments were carried out to demonstrate the potential of this method in MS applications. In the online experiment, signal enhancements were observed for dielectric plates with different geometries, distances of the electrospray needle axis from the MS inlet, and various compounds. For example, in the case of acetaminophen (15 μM), the signal enhancement was up to 1.82 times (plate B) using the default distance of the electrospray needle axis from the MS inlet (d = 1.5 mm) and 12.18 times (plate C) using a longer distance (d = 7 mm).

Discharge characteristics of a microsecond pulsed underwater streamer discharge in multi-needle electrode configuration

The underwater streamer discharge has received extensive attention in the field of environmental protection, because it can generate free radicals and reactive oxygen species directly in water. The multi-needle electrode is a basic electrode configuration for achieving large-volume underwater streamer discharge. Understanding the discharge characteristics of the multi-needle electrode configuration is important for designing the large-volume discharge reactors. In this work, a multi-needle electrode that can assemble 21 needles is employed. The number of anode needles generating a streamer discharge during a single pulsed discharge and the differences in morphological characteristics between the inside and the edge of the electrode array are investigated by using an ultra-high-speed camera system. The electric field distribution of the multi-needle electrode is simulated by using the COMSOL software, and the effect of the electric field distribution on the discharge of multi-needle electrode is also studied. The discharge energy efficiency of the multi-needle electrode configuration is evaluated. It is found that the 21 needles are not discharged simultaneously during a discharge pulse. The number of discharged anode needles gradually increases and then reaches a maximum value (≤21). The maximum number of discharged anode needles during a single discharge pulse increases as the voltage and needle spacing increases. During a single discharge pulse, the filament generated from the needles at the edge of the electrode array grows longer and deviates more largely from the needle axis than that generated from the needles inside the electrode array. Such characteristics are primarily due to the disturbance of the electric field among the 21 needles. As the needle spacing decreases, the disturbance of the electric field among the 21 needles gets stronger, consequently, the discharge morphology differences between the needles at the edge and needles at the inner of the needle array become more significant, and the energy efficiency of the discharge drops remarkably.

Combined Effects of Electrical and Mechanical Stresses on Insulation Breakdown—Part I: Tree Growth of Epoxy Resin

In this study, the treeing characteristics of epoxy resin were investigated by stressing the sample parallelly or vertically to the needle axis. Results show that tensile stress accelerates the tree branch growth, and under a proper compressive stress, the tree branches are closed and suppressed. However, when the compressive stress exceeds a threshold, the shear stress plays a dominated part, which promotes the tree branches to grow in a certain angle. When the mechanical stress is vertical to the needle axis, it has a significant influence on the electrical tree length. And when the mechanical stress is parallel to the needle axis, it mainly influences the electrical tree width. After insulation breakdown, cracks are produced due to the released energy from the short-circuit current. And the cracks are vertical to the tensile stress but parallel to the compressive stress. The research results in this paper are very significant for analyzing the breakdown of the tri-post insulators in GIL.

"Photochemical Surgery" of 1D Metal-Organic Frameworks with a Site-Selective Solubilization/Crystallization Strategy.

One-dimensional (1D) hybrid MOFs are attractive if they consist of different MOF blocks with interconnected channels. However, the precision synthesis of such 1D multiblock MOFs with the desired block lengths and sequences remains a formidable challenge. Herein we propose the "photochemical surgery" method, which combines top-down and bottom-up approaches to enable the site-selective solubilization (removal)/crystallization (reconstruction) of 1D MOFs. We employed photoreactive MOFs, which were prepared by complexing either Cd2+ or Zn2+ with a mixture containing a photochromic bispyridyl ligand (PyDTEopen or PyDTZEopen) and an isophthalate (5-nitroisophthalate (nip2-) or 5-bromoisophthalate (bip2-)). These MOFs were obtained as high-aspect-ratio, needlelike, colorless crystals that bore 1D channels oriented parallel to the long needle axis. When photoreactive DTECdMOFNO2 ([Cd(nip)(PyDTEopen)(H2O)]n), for example, was immobilized at both ends with a metal alloy on a glass substrate and exposed to UV light through a photomask for 60 min in N,N-dimethylformamide/methanol (DMF/MeOH), the unmasked part was removed via solubilization to produce a 50 μm gap. The resulting specimen was immersed for 24 h at 25 °C in DMF/MeOH containing the necessary components for the construction of DTZECdMOFNO2 ([Cd(nip)(PyDTZEopen)(H2O)]n). Eventually, the gap was filled with DTZECdMOFNO2 to produce a triblock hybrid MOF (DTECdMOFNO2-DTZECdMOFNO2-DTECdMOFNO2). The result of a guest diffusion experiment confirmed that the newly formed DTZECdMOFNO2 block shared its 1D channels with the host DTECdMOFNO2 blocks. "Photochemical surgery" can be applied to synthesize 1D hybrid MOFs bearing unconventional sequences and morphologies, e.g., honeycomb- and inverted-honeycomb-patterned hybrids.

Bismuth‐Rich Intermetallic Rods with a Note of Zintl‐Phase

AbstractBlack needle‐shaped crystals of the bismuth‐rich mixed halogenide Bi21Rh4Cl6I7were obtained by slow cooling of a melt of Bi, RhI3and BiCl3. Single‐crystal X‐ray diffraction revealed an orthorhombic structure that consists of infinite intermetallic rodsBi9Rh2]3+and discrete anionic groups [BiII2Cl2I5]3−and [BiIIICl4I2]3−. The rods consist of Rh‐centered [RhBi8] polyhedra that alternately share triangular and rectangular faces. Using traditional electron counting rules, the rod can be interpreted as a covalent polymer with Rh2dumbbells bonded to molecular Bi2and Bi5units. However, a quantum‐chemical bonding analysis shows that the bonds involving Rh atoms are largely diffuse, while two‐center bonds dominate in the bismuth units. The below 240 K observed semiconducting behavior of Bi21Rh4Cl6I7is consistent with a complete localization of the valence electrons. Above 240 K, the resistance along the needle axis is largely independent of temperature.

Two-stage generative adversarial networks for metal artifact reduction and visualization in ablation therapy of liver tumors.

The strong metal artifacts produced by the electrode needle cause poor image quality, thus preventing physicians from observing the surgical situation during the puncture process. To address this issue, we propose a metal artifact reduction and visualization framework for CT-guided ablation therapy of liver tumors. Our framework contains a metal artifact reduction model and an ablation therapy visualization model. A two-stage generative adversarial network is proposed to reduce the metal artifacts of intraoperative CT images and avoid image blurring. To visualize the puncture process, the axis and tip of the needle are localized, and then the needle is rebuilt in 3D space intraoperatively. Experiments show that our proposed metal artifact reduction method achieves higher SSIM (0.891) and PSNR (26.920) values than the state-of-the-art methods. The accuracy of ablation needle reconstruction is 2.76mm average in needle tip localization and 1.64° average in needle axis localization. We propose a novel metal artifact reduction and an ablation therapy visualization framework for CT-guided ablation therapy of liver cancer. The experiment results indicate that our approach can reduce metal artifacts and improve image quality. Furthermore, our proposed method demonstrates the potential for displaying the relative position of the tumor and the needle intraoperatively.

An Electrostatically Actuated Gecko Adhesive Clutch

AbstractThis work presents a new variation on electrostatic clutches that uses gecko‐inspired adhesives instead of friction for its braking force. As a result, it requires no power or normal pressure to remain engaged or disengaged. It requires only a brief pulse of voltage to switch states. In some applications, this capability is desirable for safety reasons. As an illustration, the clutch is incorporated into the needle‐driving axis of a magnetic resonance compatible teleoperated robotic system. Adding the clutch has no effect on imaging quality and provides a fail‐safe brake to prevent the needle axis from dropping in the event of a power failure. As a second application, the clutch is integrated into a force‐controlled robotic gripper where it allows the motor to be turned off while maintaining a static grasping force. In both applications, the 20 ms response time of the clutch prototypes is advantageous to prevent any motion immediately after receiving a braking command. This work additionally presents details on the design and manufacturing process of the gecko‐inspired clutch, including a new, non‐uniform profile for the microscopic adhesive features. The fabricated prototypes are thin (305 µm per layer) and flexible. They provide a controllable, adhesive braking force of 60 kPa per layer. Multiple layers can be assembled to increase the braking force.

Microwave ablation of the lung: Comparison of 19G with 14G and 16G microwave antennas in ex vivo porcine lung.

Percutaneous image-guided thermal ablation has an increasing role in the treatment of primary and metastatic lung tumors. Although microwave ablation (MWA) has emerged advantageous as a new ablation technology, more research is needed to improve it. This study aims to investigate the ablation zone of three microwave antennas in ex vivo porcine lung. In the ex vivo standard model and porcine lung model, MWA was performed in three power output settings (50 W, 60 W, and 70 W) for 3, 6, 9, and 12 min using three microwave antennas, with outer diameter of 1.03 mm (19G), 1.6 mm (16G), and 2.0 mm (14G). A total of 108 and 216 sessions were performed (3 or 6 sessions per time setting with the 14G, 16G, and 19G microwave antennas). After the MWA was complete, we evaluated the shape and extent of the coagulation zone and measured the maximum long-axis (along the needle axis; length [L]) and maximum short-axis (perpendicular to the needle; diameter [D]) of the ablation zones using a ruler; subsequently, the sphericity index (L/D) was calculated. The sphericity index can be simplified as long-axis/short-axis. In the ex vivo standard model study, the long- and short-axis diameters and sphericity indices were not statistically different between the 14G, 16G, and 19G groups. In the ex vivo porcine lung study, the long- and short-axis diameters did not differ statistically between the 14G, 16G, and 19G groups (P < 0.05 each). The sphericity index for the 19G microwave antenna was higher than the sphericity indices for the 14G and 16G microwave antennas (P < 0.05); however, the index for the 14G microwave antenna was not statistically different than that for the 16G microwave antenna (P > 0.05). The ablation zone of the 19G antenna was the same as those of the 14G and 16G antennas in vitro. Thus, the 19G antenna may reduce the incidence of complications in lung tumor ablation.

Needle detection using ultrasound B-mode and power Doppler analyses.

Ultrasound is employed in needle interventions to visualize the anatomical structures and track the needle. Nevertheless, needle detection in ultrasound images is a difficult task, specifically at steep insertionangles. A new method is presented to enable effective needle detection using ultrasound B-mode and power Doppleranalyses. A small buzzer is used to excite the needle and an ultrasound system is utilized to acquire B-mode and power Doppler images for the needle. The B-mode and power Doppler images are processed using Radon transform and local-phase analysis to initially detect the axis of the needle. The detection of the needle axis is improved by processing the power Doppler image using alpha shape analysis to define a region of interest (ROI) that contains the needle. Also, a set of feature maps is extracted from the ROI in the B-mode image. The feature maps are processed using a machine learning classifier to construct a likelihood image that visualizes the posterior needle likelihoods of the pixels. Radon transform is applied to the likelihood image to achieve an improved needle axis detection. Additionally, the region in the B-mode image surrounding the needle axis is analyzed to identify the needle tip using a custom-made probabilistic approach. Our method was utilized to detect needles inserted in ex vivo animal tissues at shallow [ ), moderate [ ), and steep [ ]angles. Our method detected the needles with failure rates equal to 0% and mean angle, axis, and tip errors less than or equal to 0.7°, 0.6mm, and 0.7 mm, respectively. Additionally, our method achieved favorable results compared to two recently introduced needle detectionmethods. The results indicate the potential of applying our method to achieve effective needle detection in ultrasoundimages.

Relating Alkyl Chain Length of Additives to Wax Crystallization Inhibition: Toward the Rational Design of Pour Point Depressants

Precipitation of paraffin wax (long-chained n-alkanes) from engine oil and fuel distillates at low temperatures is generally prevented using low-dosage polymeric additives, known as pour point depressants (PPDs). The ability of a PPD to inhibit wax crystallization is largely determined by how well its alkyl side chains interact with the waxy components present in the base oil. The current study aims to elucidate the mechanism underpinning this structure–property relationship using docosane (n-C22H46) dissolved in a mixture of dodecane and toluene as a model waxy oil and the homologous series of paraffins as “tailor-made” additives. By determining the wax crystal nucleation kinetics using polythermal turbidimetry measurements, a direct link between the carbon chain length of the additive molecule and its ability to retard wax precipitation was established. Thermodynamic and structural analysis of the wax formation process using differential scanning calorimetry and small/wide-angle X-ray scattering techniques respectively revealed that the additive incorporates into the lamellar wax aggregates formed during the nucleation stage and subsequently impedes its crystallization. This mechanism is consistent with the cocrystallizing behavior of n-alkanes from multiparaffinic solutions to form a solid solution. Only additives with alkyl chains longer than the solute wax retarded nucleation and growth along the needle axis of the wax crystal because of the end-chain protrusion/bending disorder in the resultant lamellar wax crystal structure.

Dynamics of electrified jets in electrohydrodynamic atomization

An electrified jet ejected from a meniscus (or Taylor cone) can further disintegrate into fine drops with different modes in electrohydrodynamic atomization (EHDA). This process has been applied into many fields because of controllable production of highly charged and monodispersed drops. However, both stable and unstable electrified jets are encountered in EHDA, usually depending on liquid physical properties and operating parameters. A series of electrified jets are visualized and the transient breakup dynamics are analyzed within an electric field. According to the geometry forms of drops or/and jets emitted from the end of a needle, periodic dripping, pulsating-jet, stable-jet, and unstable jet are clearly classified. The operating parameters versus spraying modes are also discussed, especially for propylene glycol and n-octanol. The initial velocity from the Taylor cone, jet breakup length, jet position, and the size separation effect are deeply studied. The jet velocity is significantly accelerated by electric stresses and good agreement with predicted value. The jet breakup length increases sharply as liquid flow rate increasing and slowly increases as electric potential increasing, except for small liquid flow rate where bullet cone occurs. The jet ejection point varies and gradually deflects off needle axis with an increase in electric potential. The ‘size separation effect’ can help improve the quality of printing by removed highly charged satellite drops.

Needle Shape Sensing With Fabry-Perot Interferometers

A novel approach for fiber optics shape sensing, applicable to mini-invasive bio-medical devices, is presented. A kinematic model based on rotation vector is established and used to predict the trajectory. The movement of the flexible needle caused by two control inputs (the straight forward and the bevel orientation velocity) is described as the circular motion around the equivalent axis and the rotation of the needle axis. The model is simple, precise and efficient, and has an acceptable reconstruction effect on complex spatial curves. With the characteristics of compact structure (less than $100~ \mu \text{m}$ ), high strain sensitivity, low temperature sensitivity and ultra-low cost, Fabry-Perot interferometer (FPI) is used for curvature sensing. Calibration experiments show that FPI has higher (more than three times) curvature sensitivity and lower curvature-temperature cross sensitivity than fiber Bragg grating. The three dimensional shape sensing is obtained by converting the measured bending curvature and shape deformation using the proposed kinematic model.

Insight into Canary Island pine physiology provided by stable isotope patterns of water and plant tissues along an altitudinal gradient.

The Canary Islands, an archipelago east of Morocco's Atlantic coast, present steep altitudinal gradients covering various climatic zones from hot deserts to subalpine Mediterranean, passing through fog-influenced cloud forests. Unlike the majority of the Canarian flora, Pinus canariensis C. Sm. ex DC. in Buch grow along most of these gradients, allowing the study of plant functioning in contrasting ecosystems. Here we assess the water sources (precipitation, fog) of P. canariensis and its physiological behavior in its different natural environments. We analyzed carbon and oxygen isotope ratios of water and organics from atmosphere, soil and different plant organs and tissues (including 10-year annual time series of tree-ring cellulose) of six sites from 480 to 1990m above sea level on the Canary Island La Palma. We found a decreasing δ18O trend in source water that was overridden by an increasing δ18O trend in needle water, leaf assimilates and tree-ring cellulose with increasing altitude, suggesting site-specific tree physiological responses to relative humidity. Fog-influenced and fog-free sites showed similar δ13C values, suggesting photosynthetic activity to be limited by stomatal closure and irradiance at certain periods. In addition, we observed an 18O-depletion (fog-free and timberline sites) and 13C-depletion (fog-influenced and fog-free sites) in latewood compared with earlywood caused by seasonal differences in: (i) water uptake (i.e., deeper ground water during summer drought, fog water frequency and interception) and (ii) meteorological conditions (stem radial growth and latewood δ18O correlated with winter precipitation). In addition, we found evidence for foliar water uptake and strong isotopic gradients along the pine needle axis in water and assimilates. These gradients are likely the reason for an unexpected underestimation of pine needle water δ18O when applying standard leaf water δ18O models. Our results indicate that soil water availability and air humidity conditions are the main drivers of the physiological behavior of pine along the Canary Island's altitudinal gradients.

Accuracy of an in vivo dosimetry-based source tracking method for afterloading brachytherapy - A phantom study.

To report on the accuracy of an in vivo dosimetry (IVD)-based source tracking (ST) method for high dose rate (HDR) prostate brachytherapy (BT). The ST was performed on a needle-by-needle basis. A least square fit of the expected to the measured dose rate was performed using the active dwell positions in the given needle. Two fitting parameters were used to determine the position of each needle relative to the IVD detector: radial (away or toward the detector) and longitudinal (along the axis of the treatment needle). The accuracy of the ST was assessed in a phantom where the geometries of five HDR prostate BT treatments previously treated at our clinic were reproduced. For each of the five treatment geometries, one irradiation was performed with the detector placed in the middle of the implant. Furthermore, four additional irradiations were performed for one of the geometries where the detector was retracted caudally in four steps of 10-15mm and up to 12mm inferior of the most inferior active dwell position, which represented the prostate apex. The time resolved dose measurements were retrieved at a rate of 20Hz using a detector based on an Al2 O3 :C radioluminescence crystal, which was placed inside a standard BT needle. Individual calibrations of the detector were performed prior to each of the nine irradiations. Source tracking could be applied in all needles across all nine irradiations. For irradiations with the detector located in the middle region of the implant (a total of 89 needles), the mean±standard deviation (SD, k=1) accuracy was -0.01mm±0.38mm and 0.30mm±0.38mm in the radial and longitudinal directions, respectively. Caudal retraction of the detector did not lead to reduced accuracy as long as the detector was located superior to the most inferior active dwell positions in all needles. However, reduced accuracy was observed for detector positions inferior to the most inferior active dwell positions which corresponded to detector positions in and inferior to the prostate apex region. Detector positions in the prostate apex and 12mm inferior to the prostate resulted in mean±SD (k=1) ST accuracy of 0.7mm±1mm and 2.8mm±1.6mm, respectively, in radial direction, and -1.7mm±1mm and -2.1mm±1.1mm, respectively, in longitudinal direction. The largest deviations for the configurations with those detector positions were 2.6 and 5.4mm, respectively, in the radial direction and -3.5 and -3.8mm, respectively, in the longitudinal direction. This phantom study demonstrates that ST based on IVD during prostate BT is adequately accurate for clinical use. The ST yields submillimeter accuracy on needle positions as long as the IVD detector is positioned superior to at least one active dwell position in all needles. Locations of the detector inferior to the prostate apex result in decreased ST accuracy while detector locations in the apex region and above are advantageous for clinical applications.

Needle artifact characteristics and insertion accuracy using a 1.2 T open MRI scanner: A phantom study

PurposeTo evaluate the characteristics of needle artifacts and the accuracy of needle insertion using a 1.2 Tesla open magnetic resonance imaging (MRI) system in a phantom. Materials and methodsFirst, the apparent width of the needle on the MRI and the needle tip position error of 16- and 18-gauge MRI-compatible introducer needles and a 17-gauge cryoneedle were examined with different needle angles (0°, 30°, 45°, 60°, and 90°) to the main magnetic field (B0), sequence types (balanced steady-state acquisition with rewound gradient echo [BASG] and T2-weighted fast spin echo [FSE] sequence), and frequency encoding directions. Second, the accuracy of needle insertion was evaluated after 10 MRI fluoroscopy-guided insertions in a phantom. ResultsThe apparent needle widths was larger when the angle of the needle axis relative to B0 was larger. The needles appeared larger on BASG than on T2-weighted FSE images, with the largest apparent widths of 16-, 17-, and 18-gauge needles of 14.3, 11.6, and 11.0mm, respectively. The apparent needle tip position was always more distal than the actual position on BASG images, with the largest longitudinal error of 4.0mm. Meanwhile, the 16- and 18-gauge needle tips appeared more proximal on T2-weighted FSE images with right-to-left frequency encoding direction. The mean accuracy of MRI fluoroscopy-guided needle insertion was 3.1mm. ConclusionThese experiments clarify the characteristics of needle artifacts in a 1.2 Tesla open MRI. With this system, the MRI fluoroscopy-guided needle insertion demonstrated an acceptable accuracy for clinical use.

Automatic needle tracking using Mask R-CNN for MRI-guided percutaneous interventions.

Accurate needle tracking provides essential information for MRI-guided percutaneous interventions. Passive needle tracking using MR images is challenged by variations of the needle-induced signal void feature in different situations. This work aimed to develop an automatic needle tracking algorithm for MRI-guided interventions based on the Mask Region Proposal-Based Convolutional Neural Network (R-CNN). Mask R-CNN was adapted and trained to segment the needle feature using 250 intra-procedural images from 85 MRI-guided prostate biopsy cases and 180 real-time images from MRI-guided needle insertion in ex vivo tissue. The segmentation masks were passed into the needle feature localization algorithm to extract the needle feature tip location and axis orientation. The proposed algorithm was tested using 208 intra-procedural images from 40 MRI-guided prostate biopsy cases, and 3 real-time MRI datasets in ex vivo tissue. The algorithm results were compared with human-annotated references. In prostate datasets, the proposed algorithm achieved needle feature tip localization error with median Euclidean distance (dxy) of 0.71mm and median difference in axis orientation angle (dθ) of 1.28°, respectively. In 3 real-time MRI datasets, the proposed algorithm achieved consistent dynamic needle feature tracking performance with processing time of 75ms/image: (a) median dxy = 0.90mm, median dθ = 1.53°; (b) median dxy = 1.31mm, median dθ = 1.9°; (c) median dxy = 1.09mm, median dθ = 0.91°. The proposed algorithm using Mask R-CNN can accurately track the needle feature tip and axis on MR images from in vivo intra-procedural prostate biopsy cases and ex vivo real-time MRI experiments with a range of different conditions. The algorithm achieved pixel-level tracking accuracy in real time and has potential to assist MRI-guided percutaneous interventions.

Reliable and accurate needle localization in curvilinear ultrasound images using signature-based analysis of ultrasound beamformed radio frequency signals.

Ultrasound imaging is used in many minimally invasive needle insertion procedures to track the advancing needle, but localizing the needle in ultrasound images can be challenging, particularly at steep insertion angles. Previous methods have been introduced to localize the needle in ultrasound images, but the majority of these methods are based on ultrasound B-mode image analysis that is affected by the needle visibility. To address this limitation, we propose a two-phase, signature-based method to achieve reliable and accurate needle localization in curvilinear ultrasound images based on the beamformed radio frequency (RF) signals that are acquired using conventional ultrasound imaging systems. In the first phase of our proposed method, the beamformed RF signals are divided into overlapping segments and these segments are processed to extract needle-specific features to identify the needle echoes. The features are analyzed using a support vector machine classifier to synthesize a quantitative image that highlights the needle. The quantitative image is processed using the Radon transform to achieve a reliable and accurate signature-based estimation of the needle axis. In the second phase, the accuracy of the needle axis estimation is improved by processing the RF samples located around the signature-based estimation of the needle axis using local phase analysis combined with the Radon transform. Moreover, a probabilistic approach is employed to identify the needle tip. The proposed method is used to localize needles with two different sizes inserted in ex vivo animal tissue specimens at various insertion angles. Our proposed method achieved reliable and accurate needle localization for an extended range of needle insertion angles with failure rates of 0% and mean angle, axis, and tip errors smaller than or equal to , 0.6mm, and 0.7mm, respectively. Moreover, our proposed method outperformed a recently introduced needle localization method that is based on B-mode image analysis. These results suggest the potential of employing our signature-based method to achieve reliable and accurate needle localization during ultrasound-guided needle insertion procedures.

Performance, intestinal morphometry, and incubation parameters of broiler chickens submitted to in ovo feeding with different techniques and amino acids

The objective of this research was to evaluate techniques, incubation period, and effects of amino acids in ovo feeding. First, 240 hatching eggs were selected and distributed in a 2 × 3 factorial arrangement (two techniques and 3 d). The parameters of incubation, relative weight of gastrointestinal organs, and classification of embryonic mortality were evaluated. In the second stage, 720 hatching eggs were incubated with five treatments: control, methionine (20 and 30 mg), and lysine (20 and 30 mg). These animals were housed during 14 d. The animals were divided with five treatments, nine replicates, and groupings based on sex. Incubation parameters, performance, intestinal morphometry, and relative weight of digestive tract organs were evaluated. The results indicate that the technique using a 45° needle axis passing through the air chamber hinders hatchability. In the organ weighing, there was no difference between the evaluated factors. For intestinal morphometry, there was only a significant difference between the dose factor for the crypt villi and crypt diameter. To conclude, the technique using a 90° angle without passing through the air chamber is safer for the embryos. The inoculation of methionine (20 and 30 mg) obtained data similar to the control group.