Surface Landmarks Research Articles

Should we abandon landmark-based technique for caudal anesthesia in neonates and infants?

Caudal anesthesia is a landmark-based technique with ultrasound guidance occasionally used in the absence of landmarks. The current surface landmark remains a popular approach due to its desirable success rate. However, incomplete ossification of the posterior vertebral elements can make this procedure for neonatal caudal anesthesia difficult. The aim of this study was to describe the anatomical relationship of the posterior superior iliac spines (PSISs) to the sacral cornua in infants using ultrasound. A total of 26 healthy infants (17 female; mean age 13 weeks) were scanned by an experienced radiologist in the prone position with hip and knee joints flexed. The PSISs and sacral cornua were identified clinically then using ultrasound to assess whether these markings corresponded with the clinical markings. The distance between the PSISs and the distance between the tip of the PSIS and tip of the sacral cornu were measured using ultrasound. The PSISs were clinically identified in all babies, but the sacral cornua were not palpable in four babies (15%). The PSISs and sacral cornua were easily visualized using ultrasound in all participants. The mean distance between the two left and right PSISs was 3.4 ± 0.5 cm; the mean distance between the PSISs and cornu was 2.5 ± 0.5 cm on the left and right. This study showed that the current landmark (equilateral triangle) for infant caudal anesthesia is unreliable. Importantly, the sacral hiatus is clinically identifiable only if the sacral cornua are palpable; otherwise, using ultrasound is essential.

Lumbar plexus block surface landmarks as assessed by computed axial tomography in adult patients with scoliosis: a case series

Lumbar plexus (LP) block is a common and useful regional anesthesia technique. Surface landmarks used to identify the LP in patients with healthy spines have been previously described, with the distance from the spinous process (SP) to the skin overlying the LP being approximately two-thirds the distance from the SP to the posterior superior iliac spine (PSIS) (SP-LP:SP-PSIS ratio). In scoliotic patients, rotation of the central neuraxis may make these surface landmarks unreliable, possibly leading to an increased block failure rate and an increased incidence of complications. The objective of the present study was to describe these surface landmarks of the LP in patients with scoliosis. We selected 47 patients with known thoracolumbar scoliotic disease from our institution's radiology archives. We measured bony landmark geometry, Cobb angle, and the LP location and depth. Additionally, we calculated the SP-LP:SP-PSIS ratio for both the concave and convex sides. In scoliotic patients (31 females and 16 males), the median (range) Cobb angle was 23 (8-54) degrees. The LP depth was 7.5 (5.7-10.7) cm on the concave side of the scoliotic spine and 7.6 (5.4-10.8) cm on the convex side, while the distance from the SP-LP was 3.4 (1.9-4.7) cm on the concave side and 3.7 (2.4-5.1) cm on the convex side. The SP-LP:SP-PSIS ratio was 0.61 (0.20-0.97) and 0.65 (0.45-0.98) on the concave and convex sides, respectively. None of these distances were significantly different between sides. In patients with scoliotic disease of the spine, there is wide variability in the bony surface landmarks. The location of the LP is generally more medial than expected when compared with both modified and traditional landmarks. A review of the imaging studies and the pre-procedural ultrasound assessment of the anatomy should be considered prior to needle puncture.

Ability of pediatric emergency medicine physicians to identify anatomic landmarks with the assistance of ultrasound prior to lumbar puncture in a simulated obese model.

Lumbar punctures (LPs) are typically performed using anatomical surface landmarks. However, as body mass index increases, identifying surface landmarks becomes more difficult. Ultrasound has been proposed as a tool for identifying these landmarks prior to LP. This study evaluates the effectiveness of a brief training program in ultrasound identification of anatomical landmarks in a simulated obese model prior to completing an LP. Pediatric emergency medicine physicians completed a pretest questionnaire on ultrasound familiarity prior to an educational session. Participants utilized ultrasonography without the assistance of palpation on a simulation LP model saving images for review. Participants attempted LP on phantom models with simulated body mass indices of 35 and 40 kg/m. Time to image acquisition and successful aspiration of cerebrospinal fluid from the model were recorded. Two expert sonologists independently reviewed all images for correct landmark identification. Seven of the 19 participants had previous familiarity with ultrasound. The mean time to lumbar image acquisition significantly improved for all individuals from 176 seconds to 100 seconds (P = 0.003). Comfort level with ultrasound improved (P < 0.001) as well as comfort level in performing a lumbar ultrasound (P < 0.001). Adequate images were obtained in 96% of the attempts (55/57). The success rate at performing LP was 95% (54/57). After a brief education intervention, pediatric emergency medicine physicians with little to no previous training in ultrasound can obtain adequate lumbar anatomic images and successfully perform LP in a simulated obese model. Comfort level with ultrasound significantly improves with a short course in ultrasound fundamentals.

Development of an Optimization Method for Locating the Pelvis in an Automobile Seat

The position and orientation of a vehicle occupant's pelvis are important for seat design and the provision of safety belts. However, the direct measurement of pelvis location in a vehicle seat is difficult due to interference from the vehicle and its seat structure, as well as driver factors such as abdomen adiposity. An optimization method was developed to locate the driver's pelvis based on the kinematic relationships between the pelvis bony landmarks, body landmarks, and skeletal joint locations measured in a laboratory “hardseat” that allows access to posterior landmarks. The method accounts for variation in flesh margins at pelvis landmarks. Body landmark locations were measured using a coordinate measurement machine for 90 men and women in the hardseat and a vehicle seat set to 9 driver package conditions. Pelvis locations in the vehicle seat were calculated using two supra-patella landmarks, anterior-superior iliac spines (ASIS) surface landmarks, and L5/S1 joint location along with the pelvis kinematic linkage calculated from the hardseat for each participant. To assess the performance of the method, the intra-subject standard deviations (SD) of each participant's fitted ASIS flesh margins were evaluated. Across the 9 driver package conditions, the mean intra-subject SD of the fitted ASIS flesh margins were 5.6mm horizontal and 4.7mm vertical.. The new method provides a consistent way to calculate the position and the orientation of the pelvis in which posterior landmarks cannot be directly measured, providing improved accuracy of the pelvis position for a wide range of vehicle, seat, and safety system assessments.

External ventricular drains: Management and complications.

Background:Insertion of an External Ventricular Drain (EVD) is arguably one of the most common and important lifesaving procedures in neurologic intensive care unit. Various forms of acute brain injury benefit from the continuous intracranial pressure (ICP) monitoring and cerebrospinal fluid (CSF) diversion provided by an EVD. After insertion, EVD monitoring, maintenance and troubleshooting essentially become a nursing responsibility.Methods:Articles pertaining to EVD placement, management, and complications were identified from PubMed electronic database.Results:Typically placed at the bedside by a neurosurgeon or neurointensivist using surface landmarks under emergent conditions, this procedure has the ability to drain blood and CSF to mitigate intracranial hypertension, continuously monitor intracranial pressure, and instill medications. Nursing should ensure proper zeroing, placement, sterility, and integrity of the EVD collecting system. ICP waveform analysis and close monitoring of CSF drainage are extremely important and can affect clinical outcomes of patients. In some institutions, nursing may also be responsible for CSF sampling and catheter irrigation.Conclusion:Maintenance, troubleshooting, and monitoring for EVD associated complications has essentially become a nursing responsibility. Accurate and accountable nursing care may have the ability to portend better outcomes in patients requiring CSF drainage.

体表ランドマークを用いた穿刺後計測による小児内頚静脈カテーテル留置長の検討

体表ランドマークを用いた穿刺後計測による小児内頚静脈カテーテル留置長の検討

A Composite Method for Human Foot Structural Modeling

A novel method including range-sensing scanning with texture and foot anatomical structure morphing basing on OpenSim is proposed. Palpation of important anatomical landmarks on foot surface was conducted by a physical therapist, and a range-sensing device, Microsoft Kinect sensor, was adopted for the 3D textured model acquisition. 3D coordinate data of the landmarks were measured and harnessed in OpenSim for subject-specific skeletal scaling based on a generic foot musculoskeletal model. The muscle attachment point coordinates derived from an anatomy database basing on sampling from East Asia people were used for muscle modelling. Then the 3D textured foot surface was registered with the morphed anatomical structures so that an integrated foot model was generated. The surface landmark locations were then compared with the corresponding internal bony sites and the errors were calculated to evaluate the accuracy and validity of this method. The potential error sources such as soft tissue thickness and scaling error were also mentioned and discussed. This technique is useful to create individual anatomically accurate human digital models for product design and development.

Assessment of Cervical Screw Trajectory Using 3-Dimensional Software Planning

Objective: It is important and helpful for surgeons to understand the correlation between spinal anatomy and screw trajectory before surgery. We aimed to assess a simple technique using 3D imaging software available on the hospital intranet for visual and quantitative feedback to prepare surgeons for an appropriate entry point and safe trajectory when placing cervical screws. Methods: A total of 59 cervical screws were inserted from C1 to T1 in 12 consecutive patients using this technique. First, a single CT optimal slice was selected from 3D CT images of the cervical spine to determine the intervals of bilateral entry points and lateral angle. Next, this 3D image was rotated to the lateral angle. Finally, bone was cut out on the entry point using subtractive manipulation, which removed the core of the pedicle or lateral mass. Screw trajectory was indicated, and surgeons could assess the correlation between surface landmarks, spinal anatomy, and screw trajectory. Posterior cervical fusion was performed using fluoroscopy. Postoperative outcomes and incidence of complications were retrospectively assessed. Results: One perforation (1.4%) was identified on postoperative CT images. No vascular injuries occurred. Differences in the intended entry point location and lateral angle of the screw from actual postoperative values were 1.49 ± 1.23 mm and 5.46。 ± 4.46。, respectively. Conclusions: A novel 3D CT imaging assessment underwent in cervical screw fixation. This technique is easily accessible on the hospital intranet and provides training in cervical screw placement for fellows. Surgeons can simulate screw placement and share surgical strategy.

Microsurgical anatomy of the posterior median septum of the human spinal cord.

The aim of this study was to analyze the topographical anatomy of the dorsal spinal cord (SC) in relation to the posterior median septum (PMS). This included the course and variations in the PMS, and its relationship to and distance from other dorsal spinal landmarks. Microsurgical anatomy of the PMS was examined in 12 formalin-fixed adult cadaveric SCs. Surface landmarks such as the dorsal root entry zone (DREZ), the denticulate ligament, the architecture of the leptomeninges and pial vascular distribution were noted. The PMS was examined histologically in all spinal segments. The PMS extended most deeply at spinal segments C7 and S4. This was statistically significant for all spinal segments except C5. The PMS was shallowest at segments T4 and T6, where it was statistically significantly thinner than at any other segment. In 80% of the SCs, small blood vessels were identified that traveled in a rostrocaudal direction in the PMS. The longest distance between the PMS and the DREZ was at the C1-C4 vertebral levels and the shortest distance was at the S5 level. Prevention of deficits following a dorsal midline neurosurgical approach to deep-seated SC lesions requires careful identification of the midline of the cord. The PMS and septum define the midline on the dorsum of the SC and their accurate identification is essential for a safe midline surgical approach. In this anatomical study, we describe the surface anatomy of the dorsal SC and its relationship with the PMS, which can be used to determine a safe entry zone into the SC.

Surface and boney landmarks for sacral neuromodulation: a cadaveric study.

Standard external landmarks have been suggested as a guide for in-office percutaneous nerve evaluation (PNE), but validity of these landmarks has not been assessed. Our objective was to determine whether the standard 9 cm from the tip of the coccyx indicates the position of the S3 sacral foramen and whether other boney landmarks and measurements improved positioning. Measurements and distances between external boney landmarks were obtained in 22 embalmed cadavers. Spinal needles were placed 9 cm superior to the coccyx and 2 cm lateral to midline bilaterally. After dissection, internal measurements relating to sacral length, position of S3, and location of the needle in relation to S3 were recorded. Correlations among measured variables were assessed using descriptive statistics. Mean distance from the tip of coccyx to S3 was 9.26 cm (±0.84), from S3 to midline 2.30 cm (±0.2); from needle to S3 1.25 cm, and needle placement was as likely to be placed above or below S3; and S2-S3 and S3-S4 interforamenal distance 1.48 cm (±0.30) and 1.48 cm (±0.24), respectively. Mean distance from S3 to sacroiliac joint (SIJ) was shorter than S2 to SIJ. All associations between external measurements and length from tip of coccyx to S3 were not significant. A distance 9 cm from the tip of the coccyx is a reasonable starting landmark for in-office blind PNE. However, given the variability in coccyx length, caution should be taken; also, sensory-motor response is necessary to confirm proper placement.

English

Spinal anesthesia can be challenging in young obese patients and in elderly age group (>65yrs). The surface landmarks observed by clinical palpation can be less helpful in these patients (1-7).The purpose of this study is to do pre procedural ultrasound and clinical examination of the lumbar spine in the same group of patients and comparing them to space finally in which the procedure was performed. The aim is to find out the usefulness of sonography in assessing the difficulty of spinal anesthesia in young patients ( 40 years expertise is still needed in using this technique. This calls in for routine use of pre procedural sound screening for all anticipated difficult spinals.

Displacement and stress distribution of the maxillofacial complex during maxillary protraction with buccal versus palatal plates: finite element analysis

The aim of this study was to analyse the displacement and stress distribution in the maxillofacial complex during maxillary protraction with buccal and palatal plates using three-dimensional finite element analysis. Three anchorage appliance models-palatal plate (Type A), miniplate at the infrazygomatic crest (Type B), and conventional tooth-borne appliance (Type C)-were designed and integrated into a skull model. Protraction force was 500 g per side and force direction was forward and 30 degree downward to the maxillary occlusal plane. The stress distribution around the circum-maxillary sutures and the displacement of the surface landmarks were analysed. All models showed forward and upward displacement at anterior nasal spine, Point A, and prosthion and forward and downward displacement at posterior nasal spine resulting in a counter-clockwise rotation. This anterior displacement was greatest in Type A. At the maxillary process of the zygoma, upward movement was shown only in Type A, whereas downward movement was observed in Types B and C. The greatest stresses in Type A were at the pterygomaxillary and the zygomaticotemporal sutures. Type B showed the greatest stress at the frontomaxillary suture. Type A showed asymmetric results; however, it was not of clinical significance. The palatal plate resulted in wider stress distribution and more forward displacement compared to miniplate at the infrazygomatic crest area and conventional tooth-borne appliances. It might be recommended to consider the application of the palatal plate for maxillary protraction in Class III patients.

Surface landmark quantification of embryonic mouse craniofacial morphogenesis.

BackgroundMorphometric quantification of subtle craniofacial variation in studies of experimentally modified embryonic mice has proved valuable in determining the effects of developmental perturbations on craniofacial morphogenesis. The direct comparison of landmark coordinate data from embryos of many different mouse strains and mouse models can advance our understanding of the bases for craniofacial variation. We propose a standard set of craniofacial surface landmarks, for use with embryonic day (E) 10.5-12.5 mice, to serve as the foundation for this type of data compilation and analysis. We quantify the intra- and inter-observer landmark placement variation associated with each landmark and determine how the results of a simple ontogenetic analysis might be influenced by selection of landmark set.ResultsIntraobserver landmark placement error for experienced landmarkers generally remains below 0.1 mm, with some landmarks exhibiting higher values at E11.5 and E12.5. Interobserver error tends to increase with embryonic age and those landmarks defined on wide inflections of curves or facial processes exhibit the highest error. Landmarks with highest intra- or inter-observer are identified and we determine that their removal from the dataset does not significantly change the vectors of craniofacial shape change associated with an ontogenetic regression.ConclusionsOur quantification of landmark placement error demonstrates that it is preferable for a single observer to identify all landmark coordinates within a single study and that significant training and experience are necessary before a landmarker can produce data for use in larger meta-analyses. However, we are confident that this standard landmark set, once landmarks with higher error are removed, can serve as a foundation for a comparative dataset of facial morphogenesis across various mouse populations to help identify the developmental bases for phenotypic variation in the craniofacial complex.

Laparoscopic determination on the incidences and types of Rouviere's sulcus in Chinese

Objective To observe and record the incidences and types of Rouviere's sulcus in Chinese to come up with a classification of Rouviere's sulcus.Methods This prospective study was conducted on 812 consecutive patients who underwent laparoscopic cholecystectomy in our department from March 2010 to September 2012.The incidences and types of Rouviere's sulcus were documented.Results The open type of Rouviere's sulcus was visualized in 638 patients(78.6％),the partially fused type in 145 patients,and the totally fused type in 29 patients.Conclusions Rouviere's sulcus is an important surface landmark of the hilar pedicle and it could be identified in the great majority of patients.We for the first time in the world,proposed a classification of the Rouviere's sulcus which may contribute to a better understanding of hepatobiliary anatomy. Key words: Liver; Rouviere's sulcus; Laparoscopy

Surface marking of axillary vein

IntroductionPrecise identification of axillary vein during axillary lymph node dissection is an important step. Trainees in surgery often find it difficult to identify the exact level of axillary vein because surface marking of axillary vein is not described in most standard textbooks of anatomy and operative surgery. MethodsWe have identified the surface markings for axillary vein on 150 patients undergoing axillary lymph node dissection. We mark the axillary crease of skin between upper arm and axilla and identify two distinct dimples at the anterior and posterior ends of this skin crease. We then place a finger horizontally at the midpoint between the two dimples directed towards lateral edge of pectoralis major muscle. This position of finger marks the surface anatomy of underlying axillary vein. ResultsThe axillary vein was found to be located deep to this surface marking. In some patients, the marking was found to overlap the width of axillary vein partially. However, in all cases atleast some part of vein lies deep to the midpoint of two axillary crease dimples. DiscussionA simple and a reliable technique of locating the axillary vein using surface landmarks is described.

TU‐F‐BRF‐02: MR‐US Prostate Registration Using Patient‐Specific Tissue Elasticity Property Prior for MR‐Targeted, TRUS‐Guided HDR Brachytherapy

Purpose:High‐dose‐rate (HDR) brachytherapy has become a popular treatment modality for prostate cancer. Conventional transrectal ultrasound (TRUS)‐guided prostate HDR brachytherapy could benefit significantly from MR‐targeted, TRUS‐guided procedure where the tumor locations, acquired from the multiparametric MRI, are incorporated into the treatment planning. In order to enable this integration, we have developed a MR‐TRUS registration with a patient‐specific biomechanical elasticity prior.Methods:The proposed method used a biomechanical elasticity prior to guide the prostate volumetric B‐spline deformation in the MRI and TRUS registration. The patient‐specific biomechanical elasticity prior was generated using ultrasound elastography, where two 3D TRUS prostate images were acquired under different probe‐induced pressures during the HDR procedure, which takes 2‐4 minutes. These two 3D TRUS images were used to calculate the local displacement (elasticity map) of two prostate volumes. The B‐spline transformation was calculated by minimizing the Euclidean distance between the normalized attribute vectors of the prostate surface landmarks on the MR and TRUS. This technique was evaluated through two studies: a prostate‐phantom study and a pilot study with 5 patients undergoing prostate HDR treatment. The accuracy of our approach was assessed through the locations of several landmarks in the post‐registration and TRUS images; our registration results were compared with the surface‐based method.Results:For the phantom study, the mean landmark displacement of the proposed method was 1.29±0.11 mm. For the 5 patients, the mean landmark displacement of the surface‐based method was 3.25±0.51 mm; our method, 1.71±0.25 mm. Therefore, our proposed method of prostate registration outperformed the surfaced‐based registration significantly.Conclusion:We have developed a novel MR‐TRUS prostate registration approach based on patient‐specific biomechanical elasticity prior. Successful integration of multi‐parametric MR and TRUS prostate images provides a prostate‐cancer map for treatment planning, enables accurate dose planning and delivery, and potentially enhances prostate HDR treatment outcome.

MO‐C‐17A‐04: Forecasting Longitudinal Changes in Oropharyngeal Tumor Morphology Throughout the Course of Head and Neck Radiation Therapy

Purpose:To generate, evaluate, and compare models that predict longitudinal changes in tumor morphology throughout the course of radiation therapy.Methods:Two morphology feature vectors were used to describe the size, shape, and position of 35 oropharyngeal GTVs at each treatment fraction during intensity‐modulated radiation therapy. The feature vectors comprised the coordinates of the GTV centroids and one of two shape descriptors. One shape descriptor was based on radial distances between the GTV centroid and 614 GTV surface landmarks. The other was based on a spherical harmonic decomposition of these distances. Feature vectors over the course of therapy were described using static, linear, and mean models. The error of these models in forecasting GTV morphology was evaluated with leave‐one‐out cross‐validation, and their accuracy was compared using Wilcoxon signed‐rank tests. The effect of adjusting model parameters at 1, 2, 3, or 5 time points (adjustment points) was also evaluated.Results:The addition of a single adjustment point to the static model decreased the median error in forecasting the position of GTV surface landmarks by 1.2 mm (p&lt;0.001). Additional adjustment points further decreased forecast error by about 0.4 mm each. The linear model decreased forecast error compared to the static model for feature vectors based on both shape descriptors (0.2 mm), while the mean model did so only for those based on the inter‐landmark distances (0.2 mm). The decrease in forecast error due to adding adjustment points was greater than that due to model selection. Both effects diminished with subsequent adjustment points.Conclusion:Models of tumor morphology that include information from prior patients and/or prior treatment fractions are able to predict the tumor surface at each treatment fraction during radiation therapy. The predicted tumor morphology can be compared with patient anatomy or dose distributions, opening the possibility of anticipatory re‐planning.American Legion Auxiliary Fellowship; The University of Texas Graduate School of Biomedical Sciences at Houston

Noninvasive 3-dimensional evaluation of periorbital asymmetry in isolated unilateral orbital floor fractures.

The study was carried out to evaluate the degree of asymmetry between the injured and contralateral periorbital region in isolated orbital floor fractures after surgery. The periorbital asymmetry of 35 patients with medium-sized orbital floor fractures that were surgically treated with alloplastic resorbable implants was evaluated and compared with that of a healthy control group using an optical 3-dimensional facial scanner. Distance measurements between facial surface landmarks, as well as volume measurements between the original image and an automatically generated mirror image, were performed using commercially available software. There were no statistically significant differences in the distance measurements (P > .05) and volume measurements (P > .05) within the groups or when the study group and control group were compared using the Student t test. Alloplastic resorbable implants can restore medium defects of the orbital floor without significant periorbital asymmetry. Automatically constructed mirror images can be a helpful tool for detecting asymmetries in faces.

Relationship Between the Superior Nuchal Line and the Lower Edge of the Transverse Sinus

Even if image-guided methods have been used, surface landmarks are still important references in retrosigmoid craniotomy. The superior nuchal line (SNL) was thought to be roughly parallel to and below the lower edge of the transverse sinus (LETS). We intended to determine the relationship between the SNL and the LETS and verify the reliability of the SNL in locating the LETS. In total 72 human skull sides, the relationship between the SNL and the LETS was studied. The SNL was roughly parallel to and below the LETS in only 27 sides (37.5%) in our study. Totally, the SNL was roughly parallel to or just over the LETS in 81.9% of all sides. The SNL was obviously unparallel to the LETS in 13 sides (18.1%). Of the 13 sides, 6 difference types of relationship between the SNL and the LETS could be found. In our study, we got different result: the relationship between the SNL and the LETS seemed to be more variable; however, the SNL is still a useful surface landmark in retrosigmoid craniotomies. But considering the anatomic variability, it should be individualized by combining surface landmarks with image-guided methods.

Surface and Boney Landmarks for Sacral Neuromodulation: A Cadaveric Study

To determine whether 9 cm from the tip of the coccyx correlates with the position of the S3 sacral foramen. Secondarily, to examine other external and internal boney landmarks and measurements that correlate with the position of S3.