Needle Orientation Research Articles

Oblique needle segmentation and tracking for 3D TRUS guided prostate brachytherapy

An algorithm was developed in order to segment and track brachytherapy needles inserted along oblique trajectories. Three-dimensional (3D) transrectal ultrasound (TRUS) images of the rigid rod simulating the needle inserted into the tissue-mimicking agar and chicken breast phantoms were obtained to test the accuracy of the algorithm under ideal conditions. Because the robot possesses high positioning and angulation accuracies, we used the robot as a "gold standard," and compared the results of algorithm segmentation to the values measured by the robot. Our testing results showed that the accuracy of the needle segmentation algorithm depends on the needle insertion distance into the 3D TRUS image and the angulations with respect to the TRUS transducer, e.g., at a 10 degrees insertion anglulation in agar phantoms, the error of the algorithm in determining the needle tip position was less than 1 mm when the insertion distance was greater than 15 mm. Near real-time needle tracking was achieved by scanning a small volume containing the needle. Our tests also showed that, the segmentation time was less than 60 ms, and the scanning time was less than 1.2 s, when the insertion distance into the 3D TRUS image was less than 55 mm. In our needle tracking tests in chicken breast phantoms, the errors in determining the needle orientation were less than 2 degrees in robot yaw and 0.7 degrees in robot pitch orientations, for up to 20 degrees needle insertion angles with the TRUS transducer in the horizontal plane when the needle insertion distance was greater than 15 mm.

Sci‐AM1 Sat ‐ 02: Dynamic intraoperative prostate brachytherapy

The aim of this paper is to develop a dynamic intraoperative prostate brachytherapy system in order to deal with variabilities in the current procedure. System consists of 3D TRUS imaging, a robot and software for prostate segmentation, intraoperative planning, oblique needle segmentation and tracking, seed segmentation, and 3D dose planning. The robot and 3D TRUS coordinate systems are unified with robot and image calibrations. In 3D TRUS images, the prostate is segmented using the discrete dynamic contour method, and optimal implantation plan is performed by using geometric optimization followed by simulated annealing. The inserted needles are segmented and tracked using grey‐level change in near real‐time, and seed segmentation is performed using 3D line segment patterns. Needle placement accuracy of the robot at the “patient” skin was 0.15mm±0.06mm, and needle angulation error was 0.07°. Needle targeting accuracy was 0.79mm±0.32mm. The average difference between manual and the prostate segmentation algorithm of prostate boundaries was −0.20±0.28mm. In our needle tracking tests, errors in determining needle orientation were less than 2° in robot yaw and 0.7° in robot pitch orientations, for up to 20° needle insertion angles when the needle insertion distance was greater than 15mm. The true‐positive rates for the seed segmentation algorithm in 3D TRUS images were 100% for agar and 93% for chicken phantoms. The result of this work provides a tool to achieve dynamic intraoperative prostate brachytherapy using 3D TRUS imaging and robotic assistance together with efficient segmentation software.

MO-E-T-618-03: Dynamic Intraoperative Prostate Brachytherapy Using 3D TRUS Guidance with Robotic Assistance

Purpose: Develop a dynamic intraoperative prostate brachytherapy system, in which all phases of the procedure are performed in one session, including planning, monitoring of prostate changes, dynamic re-planning, optimal needle insertion including oblique trajectories and automatic seed localization in US images, to deal with variabilities in the current procedure. Method and Materials: The system consists of 3D TRUS imaging, a robot and software tools for prostate segmentation, intraoperative planning, oblique needle segmentation and tracking, seed segmentation, and 3D dose planning. The robot and 3D TRUS coordinate systems are unified with robot and image calibrations. In 3D TRUS images, the prostate is segmented using discrete dynamic contour method, and optimal implantation plan is performed by applying geometric optimization followed by simulated annealing. The robot can be controlled to guide the needle to target points in 3D TRUS images along oblique trajectories accurately and consistently. The inserted needles are segmented and tracked using grey-level change, and seed segmentation is performed using 3D line segment patterns. Results: Needle placement accuracy of the robot at “patient” skin was 0.15mm±0.06mm, and needle angulation error was 0.07°. Needle targeting accuracy was 0.79mm±0.32mm. The average difference between manual and the prostate segmentation algorithm of prostate boundaries was −0.20±0.28mm. In our needle tracking tests, errors in determining needle orientation were less than 2° in robot yaw and 0.7° in robot pitch orientations, for up to 20° needle insertion angles when the needle insertion distance was greater than 15mm. The true-positive rates for the seed segmentation algorithm in 3D TRUS images were 100% for agar and 93% for chicken phantoms. With optimal planning tools provided, 98% of prostate volume receives 80% of dose coverage. Conclusion: The result of this work provides a tool to achieve dynamic intraoperative prostate brachytherapy using 3D TRUS imaging and robotic assistance together with efficient segmentation software.

WE‐D‐I‐609‐01: Design and Calibration of a Robotic Needle Positioning System for Small Animal Imaging Applications

Purpose: A needle‐positioning robot is being developed for three‐dimensional micro‐ultrasound guided interventions. This device will be used to perform minimally invasive injections and biopsies into small animals with high accuracy and precision. Method and Materials: The robot has three degrees of freedom for positioning the needle in three dimensions. Two rotational joints are used to control needle orientation (roll and pitch). Another joint linearly translates the needle to perform insertion. The design features a four‐bar linkage mechanism that translates the roll axis of rotation from an actuator to a remote axis that intersects the pitch and needle axes. The three intersecting axes create a remote center of motion (RCM) that acts as a fulcrum for the three‐dimensional orientation of the needle. The RCM corresponds to the insertion point of the needle into the animal. In order for the robot to achieve high accuracy, it must be calibrated to ensure that the three axes intersect at a single point, and the needle tip must be positioned at the RCM. The calibration was performed using a macro lens CCD camera to find the center of rotation about the pitch and roll axes separately. The position of the needle was adjusted until it was aligned with the RCM. Results: The range of motion is ±30°, ±45°, and 20 mm for the pitch, roll, and needle axes, respectively. Initial calibration results indicate that the distance from the needle to the pitch and roll axes are 24 ± 30 μm (mean ± standard deviation of five trials) and 18 ± 15 μm, respectively. The pitch and roll axes are separated by 11 ± 3 μm. Conclusion: The expected maximum needle positioning error computed from the calibration results is 32 μm when the needle tip is moved to the boundary of the workspace.

Substrate structure dependence of the growth modes of p-quaterphenyl thin films on gold

The variably oriented crystallite surfaces of a recrystallized polycrystalline gold sample served as substrates for the investigation of the structure dependence of p-quaterphenyl (4P) thin film growth. The films were prepared in ultrahigh vacuum by organic molecular beam evaporation. Optical microscopy, scanning electron microscopy, combined with laterally resolved electron backscatter diffraction and scanning tunnelling microscopy have been applied to determine the correlation between the substrate surface structure and 4P film morphology. Crystallite surfaces consisting of (110) terraces favour highly anisotropic needle-like 4P growth with the needle orientation normal to the Au 〈11¯0〉 directions. Atomic steps on vicinal planes with narrow terraces (< 2 nm) can also induce anisotropy in the 4P thin film growth, in particular elongated 4P islands normal to the step direction. In contrast to that, a nearly isotropic distribution of the needle orientations is observed on Au grains terminated by highly symmetric (111) or (100) crystal planes. Additionally, patches of continuous 4P layers can be found on these surfaces. There is strong evidence that the 4P molecules within the needle-like crystallites are oriented parallel to the Au surface, whereas for the continuous layers the 4P molecules are oriented nearly upright on the surface.

Remotely-Controlled Approach for Stereotactic Neurobiopsy

The objective of this study was to develop, demonstrate, and validate a remotely controlled operation scheme coupled with prospective magnetic resonance imaging (MRI)-based stereotaxy for in vivo neurosurgical applications. The novel concept of the prospective guidance scheme is to employ tomographical imaging feedback, such as MRI or CT, to facilitate prospectively the targeting process of a biopsy needle at near-real-time speed (1 image/s). Because the orientation of a biopsy needle pivoted at an entry point on die patient's skull has 2 degrees of freedom, the alignment of its trajectory to a target point can be guided by two-dimensional (2D) images whose plane is placed perpendicular to the desired trajectory. Using near-real-time 2D visual feedback during the adjustment of the alignment guide, the required trajectory alignment can be translated into a simple targeting task on a computer monitor employing a suitable graphic presentation. Also, both adjustments for the alignment and introduction of the biopsy needle were accomplished remotely with image-based feedback. The use of the method in actual MR-guided brain lesion biopsy procedures at 1.5 T showed an improved tissue yield due to the improved targeting accuracy even in the presence of brain shift. Furthermore, the postalignment trajectory can be validated immediately using near-real-time MRI scans in two orthogonal views before needle insertion. Because the final needle position is always visualized and confirmed, the consequent tissue sampling is performed with greater certainty, even in the case of a negative diagnosis. The actual targeting error was 1.53 ± 0.17 mm from an intended target location, with the maximum distance error of 1.72 mm at a depth of 85 mm. This remotely controlled surgical approach with intraoperative MRI guidance is feasible at 1.5 T, and has allowed neurosurgeons to perform neurobiopsies comfortably and efficiently in a routine clinical MR scanner. This scheme provides a unique alternative stereotactic procedure that can take full advantage of the prospective guidance potential offered by various modern tomographic imaging systems.

Feasibility of telementoring between Baltimore (USA) and Rome (Italy): the first five cases.

Telemedicine is the use of telecommunication technology to deliver healthcare. Telementoring has been developed to allow a surgeon at a remote site to offer guidance and assistance to a less-experienced surgeon. We report on our experience during laparoscopic urologic procedures with mentoring between Rome, Italy, and Baltimore, USA. Over a period of 3 months, two laparoscopic left spermatic vein ligations, one retroperitoneal renal biopsy, one laparoscopic nephrectomy, and one percutaneous access to the kidney were telementored. Transperitoneal laparoscopic cases were performed with the use of AESOP, a robotic for remote manipulation of the endoscopic camera. A second robot, PAKY, was used to perform radiologically guided needle orientation and insertion for percutaneous renal access. In addition to controlling the robotic devices, the system provided real-time video display for either the laparoscope or an externally mounted camera located in the operating room, full duplex audio, telestration over live video, and access to electrocautery for tissue cutting or hemostasis. All procedures were accomplished with an uneventful postoperative course. One technical failure occurred because the robotic device was not properly positioned on the operating table. The round-trip delay of image transmission was less than 1 second. International telementoring is a feasible technique that can enhance surgeon education and decrease the likelihood of complications attributable to inexperience with new operative techniques.

Locating steel needles in the human body using a SQUIDmagnetometer

A technique has been developed, based on magnetic field measurements, tolocalize, in three dimensions, hypodermic and sewing needles lost in the humanbody. A theoretical model for the magnetic field generated by needles has beenelaborated and experimentally validated. Using this model, the localizationtechnique gives information about needle's centre, orientation and depth. Theclinical measurements have been made using a SQUID system, with patients beingmoved under the sensor with the aid of an X-Y bed. The magnetic fieldassociated with the remanent magnetization of the needle is acquired on-lineand mapped over a plane. In all six cases that occurred, the technique allowedsurgical localization of the needles with ease and high precision. Thisprocedure can decrease the surgery time for extraction of foreign bodies by alarge factor, and also reduce the generally high odds of failure.

Coarsening of needle-shaped apatite crystals in SiO2 • Al2O3 • Na2O • K2O • CaO • P2O5 • F glass

Coarsening of needle-shaped apatite crystals was studied in a SiO2 • Al2O3 • Na2O • K2O • CaO • P2O5 • F glass. Crystal numbers and size distributions were measured by image analysis of electron micrographs obtained from slightly etched fractures of powder compacts sintered from differently annealed glass powders. Results indicate that the growth of apatite needles is controlled by diffusion-limited Ostwald ripening. Thus, the mean needle diameter and length increase with t1/3 while the crystal number decreases with t−1 due to a constant volume fraction of apatite. An invariant reduced size distribution could be found for the diameters. The measurement of needle lengths is affected by several difficulties (e.g. random needle orientation).

Infraclavicular Brachial Plexus Block

Infraclavicular brachial plexus block is a technique well suited to prolonged continuous catheter use. We used a coracoid approach to this block to create an easily understood technique. We reviewed the magnetic resonance images of the brachial plexus from 20 male and 20 female patients. Using scout films, the parasagittal section 2 cm medial to the coracoid process was identified. Along this oblique section, we located a point approximately 2 cm caudad to the coracoid process on the skin of the anterior chest wall. From this point, we determined simulated needle direction to contact the neurovascular bundle and measured depth. At the skin entry site, the direct posterior insertion of a needle will make contact with the cords of the brachial plexus where they surround the second part of the axillary artery in all images. The mean (range) distance (depth along the needle shaft) from the skin to the anterior wall of the axillary artery was 4.24 +/- 1.49 cm (2.25-7.75 cm) in men and 4.01 +/- 1.29 cm (2.25-6.5 cm) in women. Hopefully, this study will facilitate the use of this block. We sought a consistent, palpable landmark for facilitation of the infraclavicular brachial plexus block. We used magnetic resonance images of the brachial plexus to determine the depth and needle orientation needed to contact the brachial plexus. Hopefully, this study will facilitate the use of this block.

Lateral Approach to the Sciatic Nerve in the Popliteal Fossa

We describe a modification of the sciatic nerve (SN) block in the popliteal fossa through the lateral approach.After a brief anatomic study using previously reported landmarks, we propose a new needle orientation associated with a double injection technique after identification of the tibial and the common peroneal nerve. Thirty-four patients undergoing ankle or foot surgery were enrolled in this study. With patients in the supine position, the upper edge of the patella and the groove between the posterior border of the vastus lateralis and the anterior border of the tendon of the biceps femoris were identified. The needle was directed posteriorly with a 20-30[degree sign] angle relative to the horizontal plane and slightly caudal. Both nerves were individually located with a nerve stimulator and blocked with a mixture of lidocaine-bupivacaine and clonidine. In all but one case, the two nerves were easily located, and no vascular puncture was evident. Effective analgesia was obtained for a minimum of 15 h (first analgesic demand). We conclude that this technique, with a modified direction of the needle and a double stimulation, provides a very high rate of success for SN blockade in the popliteal fossa. Implications: We describe a new lateral approach to the sciatic nerve in the popliteal fossa. The needle was directed caudad and posteriorly while seeking with a nerve stimulator for the tibial and the peroneal nerves, which were blocked separately. This technique was very successful. (Anesth Analg 1998;87:79-82)

Effect of Needle Position and Orientation on Forces Experienced by Individual Needles during Needle Punching

Needle force is measured on felting needles at four different locations simultaneously using four mini-transducers mounted on the needle board of a James Hunter 12 inch model loom. The machine speed is 300 strokes/minute, needling density is 34.6 punches/cm2, and the depth of penetration is 16 mm. Results indicate that differences in the needling force between needles of the same type and needle location in the needle board are significant. Needle force is also significantly greater at the back of the needle board where the needles penetrate fresh web, compared to the front of the needle board. An absence of needles surrounding the test needles causes the test needles to experience significantly greater force.

Temporal and spatial patterns of net photosynthesis in 12-year-old loblolly pine five growing seasons after thinning

Physiological parameters were measured under natural light conditions and needle orientation from towers and walkways erected in the canopy of a loblolly pine ( Pinus taeda L.) plantation. Four silvicultural treatments were randomly assigned to the twelve plots in the fall of 1988. Plots were thinned to a density of 731 trees per hectare or left unthinned, at a density of 2990 trees per hectare. The plots were left unfertilized or fertilized with 744 kg/ha of diammonium triple superphosphate was applied. During the fifth growing season (1993) following thinning and fertilization, needle level physiology was not different with respect to the thinning treatment for fertilized or unfertilized plots. In contrast, upper crown levels within the fertilized and unfertilized plots had significantly higher light levels and photosynthetic rates than lower crown foliage. Light levels were greater in the thinned, fertilized plots than in the unthinned, fertilized plots. In contrast, no effect of thinning on canopy light levels was found in the unfertilized plots. Within crown variation in photosynthesis was strongly dependent on canopy light levels. A strong interaction of canopy level with thinning was apparent for net photosynthesis. Loblolly pine, being a shade intolerant species, showed only small physiological differences between needles from different parts of the crown. Because of the variability found in this study, more extensive sampling is needed to correctly describe the physiology of a forest canopy with adequate precision.

Bevel direction, dura geometry, and hole size in membrane puncture: Laboratory report

The cylindrical shape of the dura in vivo, as well as the needle tip deviation known to occur with beveled needle insertion, might predispose to geometric effects of needle orientation on hole size and shape during dural puncture. The object of this study was to investigate such possible effects. Standard xerographic paper was used to simulate a dura mater membrane with random fiber orientation. Rigidly mounted paper cylinders of 2-cm diameter were transfixed at 90 degrees angles to the cylinder axis with 22-gauge Quincke point spinal needles. A nonrotating drill press effected linear insertion, creating entry and exit perforations at median and paramedian positions. The bevel direction was rotated at 90 degrees angles during punctures in order to determine the effects of lateral versus transverse bevel orientation (relative to the cylinder axis) on the resultant hole morphology. With median perforation, all holes (entry and exit) were of uniform size and shape regardless of bevel orientation. Paramedian perforations of the cylinder at near tangential positions, with the bevel directed lateral to the cylinder axis, resulted in formation of a flap overlapping the margins of either the entry or exit hole but not both. Flaps formed only when the bevel faced the cylinder membrane's surface during paramedian, near tangential puncture (n = 10, P = .00001). The geometric interactions of membranes with Quincke needles lend support to the practice of needle insertion with the bevel facing laterally in order to produce smaller holes. Geometry may help to explain the reduced rate of postdural puncture headache found with Quincke bevels oriented to face laterally during midline approach and during paramedian technique, particularly when a single puncture results in aspiration of cerebrospinal fluid.

Biopsy needle susceptibility artifacts.

Understanding the appearance of thin metallic structures in magnetic resonance imaging is important for evaluating the potential role of MRI in guiding and monitoring percutaneous interventions. As most MR compatible instruments are made from materials with a susceptibility different from water, their visibility is enhanced beyond what is expected on the grounds of displaced water alone. Unfortunately, this artifactually enhanced visibility is not constant, but instead depends on a variety of factors. This article presents computer simulations of the image distortion resulting from magnetic susceptibility differences between a needle and the surrounding tissue. The simulations show not only an artifact size that is dependent on needle composition, orientation, and pulse sequence, but also a corresponding shift of the artifact center away from the actual center of the needle. These effects place limits on the accuracy of MRI-guided needle tip placement.

MRI-guided MRI arthrography of the shoulder

To develop an MR-guided technique for joint puncture in MR arthrography of the shoulder and to confirm the intracapsular position of the needle tip by visualization of the flow of contrast media into the joint. Three unfixed human shoulder joint specimens were examined on a LOT unit. The optimal point of entrance and depth for joint puncture were estimated by means of MR-compatible markers on the skin. Needle orientation and localization of the needle tip (MR-compatible 22-gauge needle) in the shoulder joint were monitored by rapid localizer gradient-echo sequences in two or thogonal planes. To confirm the intracapsular position of the needle tip, diluted gadolinium-DTPA was administered via a long connecting tube and the flow of contrast media into the joint was viewed directly on an LCD screen using real-time MR imaging (local look technique). The MR-compatible markers on the skin allowed determination of the optimal point of entrance and estimation of the depth for joint puncture. Passive visualization of the MR-compatible needle due to spin dephasing and signal loss provided adequate localization of the intra-articular needle tip position in all specimens, although significant artefacts were present on rapid localizer gradient-echo sequences with an increase in width of the apparent needle shaft. Real-time MR imaging of the flow of contrast media was possible using the local look technique and the LCD screen of the MR unit and allowed confirmation of the intracapsular position. MR-guided joint puncture and real-time MR-assisted contrast media application results in improved MR-arthrography and may replace conventional fluoroscopic guidance.

Postmyelography headache: a review.

The author reviews the topic of postdural puncture headache (PDPH) so radiologists can better understand, prevent, and treat this common complication of myelography. PDPH, a postural headache relieved by lying supine, occurs after 36.0%-58.2% of myelographic procedures performed with 22-gauge Quincke needles. It begins within 3 days and lasts 3-5 days. Thin, young women are more likely to develop PDPH. Smaller gauge needles, blunt-tip needles, a paramedian approach, and parallel orientation of a bevel needle are associated with lower PDPH rates. Intravenous hydration, no removal of cerebrospinal fluid, experience of the myelographer, and inpatient status have been inconsistently associated with lower PDPH rates. Treatment is supportive with bed rest. Oral or intravenous methylxanthine agents may be given for more severe PDPH. An epidural blood patch, although rarely needed, is very effective.

Spinal anaesthesia for Caesarean section: effect of Sprotte needle orientation

We induced spinal anaesthesia in 100 women presenting for elective Caesarean section with the mother in the right lateral position. Patients were allocated randomly to have the side eye of the 24-gauge Sprotte spinal needle pointing in one of four directions: group A, cephalad; group B, right lateral; group C, left lateral; group D, caudad. Isobaric bupivacaine 0.5% (2.5 ml) was injected over 30 s before the mother was placed supine with a 15 degree left lateral tilt. Onset time and height of the subsequent analgesic and anaesthetic blocks were assessed by a blinded observer. Onset of sensory block to T4 was significantly faster in group A (P = 0.001). There were no differences in final block height, incidence of hypotension, nausea and vomiting or ephedrine requirements.

Non-random needle orientation in 1-year-old Scots pine (Pinus sylvestris L.) seedlings when adjacent to non-shading vegetation

Two experiments were performed to test needle architecture of Scots pine (Pinus sylvestris L.) seedlings when affected by non-shading neighbouring vegetation. Both experiments showed that seedlings reacted to the presence of such adjacent vegetation by changes in needle distribution around the main stem: more needles were found on the opposite side of the main stem to where the vegetation was located. However, this reaction was confined to needles from the main stem. Responses of seedlings to dead neighbours differed from the response to live neighbours and also from the response to a black curtain substituted for plant neighbours. It is suggested that reactions are mediated by the red/far red ratio of incident light.

Modeling polarization properties of emission from soil covered with vegetation

Polarization characteristics of centimetric microwave emission from canopy-covered fields are investigated. Experimental data are compared against theoretical predictions obtained by two different models. In a simple and direct approach, vegetation is considered as a uniform absorbing and scattering slab with plane parallel boundaries, while in a more realistic description, plants are modeled as an ensemble of lossy dielectric disks and thin cylinders (needles). A parametric analysis, carried out to assess the sensitivity of the polarization index (PI) to the most significant parameters of vegetation shows that, although the PI is mainly influenced by global parameters such as leaf area index and plant water content, morphological parameters such as disk or needle dimensions and orientation distribution may play a relevant role. In particular, a model composed of a mixture of disks and needles is able to represent the negative value of PI sometimes measured over fully grown vegetation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>