Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Anatomic Landmarks”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMedDate not supplied

Three-dimensional ultrasound-based navigation combined with preoperative CT during abdominal interventions: a feasibility study.

PURPOSE: Three-dimensional (3D) intraoperative ultrasound may be easier to interpret when used in combination with less noisy preoperative image data such as CT. The purpose of this study was to evaluate the use of preoperative image data in a 3D ultrasound-based navigation system specially designed for minimally invasive abdominal surgery. A prototype system has been tested in patients with aortic aneurysms undergoing clinical assessment before and after abdominal aortic stent-graft implantation. METHODS: All patients were first imaged by spiral CT followed by 3D ultrasound scanning. The CT volume was registered to the patient using fiducial markers. This enabled us to compare corresponding slices from 3D ultrasound and CT volumes. The accuracy of the patient registration was evaluated both using the external fiducial markers (artificial landmarks glued on the patient's skin) and using intraoperative 3D ultrasound as a measure of the true positioning of anatomic landmarks inside the body. RESULTS: The mean registration accuracy on the surface was found to be 7.1 mm, but increased to 13.0 mm for specific landmarks inside the body. CT and ultrasound gave supplementary information of surrounding structures and position of the patient's anatomy. Fine-tuning the initial patient registration of the CT data with a multimodal CT to intraoperative 3D ultrasound registration (e.g., mutual information), as well as ensuring no movements between this registration and image guidance, may improve the registration accuracy. CONCLUSION: Preoperative CT in combination with 3D ultrasound might be helpful for guiding minimal invasive abdominal interventions.

Aortic Aneurysm, Abdominal↗
PubMed1990

Application and comparison of techniques for three-dimensional analysis of craniofacial anomalies.

Traditionally, cephalometric analysis has been limited to data determined from two-dimensional (2-D) cephalograms. With imaging facilities such as CT and biplanar radiography now available, the natural extension has been towards the use of three-dimensional (3-D) coordinate positions of landmarks for comparative purposes. While these data have been potentially available for several years, the accurate and reproducible extraction of anatomic landmarks suitable for comparative purposes has been limited. This paper presents results of the application of traditional comparative techniques to well determined 3-D coordinate data acquired from biplanar radiography and CT for a patient with Treacher Collins syndrome and further provides a comparison with the technique of strain analysis, often referred to as finite element analysis, which has been applied recently to craniofacial data. Comparisons of distances and angles between landmarks, landmark coordinate positions, and strains of the patient relative to experimental reference standards reveal that the essential skeletal features of Treacher Collins syndrome have been identified and quantified by the analysis techniques. Further, a measure of the significance of the deviations has been determined by comparisons with the experimental reference standards.

Cephalometry↗
PubMed2003

Assessment of the 3-d reconstruction and high-resolution geometrical modeling of the human skeletal trunk from 2-D radiographic images.

This paper presents an in vivo validation of a method for the three-dimensional (3-D) high-resolution modeling of the human spine, rib cage, and pelvis for the study of spinal deformities. The method uses an adaptation of a standard close-range photogrammetry method called direct linear transformation to reconstruct the 3-D coordinates of anatomical landmarks from three radiographic images of the subject's trunk. It then deforms in 3-D 1-mm-resolution anatomical primitives (reference bones) obtained by serial computed tomography-scan reconstruction of a dry specimen. The free-form deformation is calculated using dual kriging equations. In vivo validation of this method on 40 scoliotic vertebrae gives an overall accuracy of 3.3 +/- 3.8 mm, making it an adequate tool for clinical studies and mechanical analysis purposes.

Humans↗
PubMed1977

[Percutaneous catheterization of the subclavian vein and/or the Pirogoff angle].

The approach to the sub-clavian venous axis being carried out blindly, the difficulties encountered oblige one: - to avoid the danger (pleural dome in particular); - to guide the catheter along the sub-clavian axis (and not in the jugular vein) and therefore to know the anatomical landmarks and a precise method. A variant of the CARLE technique, that which is proposed is based on no other anatomical argument than the direction of the sub-clavian axis and of its junction. The puncture site is higher and more external, a guiding finger shows the pathway in such a way as to try and leave the dangers behind the pathway of the needle. The obligatory long tunnelization of the catheter, becomes an advantage (fights against the danger of infection) to be added to the already known advantages of this pathway.

Catheterization↗
PubMed2004

Fusion imaging in nuclear medicine--applications of dual-modality systems in oncology.

Medical imaging has become of the utmost importance in evaluating patients with cancer. Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are accurate methods for detecting cancer and related metabolic abnormalities, but they often do not provide the anatomical landmarks needed to precisely localize lesions. Magnetic resonance imaging (MRI) and computed tomography (CT) scan, on the other hand, offer excellent anatomic detail but are less sensitive because they do not provide functional detail. Fusion imaging combines functional studies with morphological ones, so overcoming the drawbacks of both modalities. Software-based fusion of independently performed scintigraphic and radiological images has proven time consuming and impractical for routine use. Recently, dual-modality integrated imaging systems (SPECT/CT and PET/CT) have been developed: the acquired images are coregistered by means of the hardware in the same session. These new devices can be particularly useful for tumour imaging. The anatomical images provide precise localization and allow the exclusion of disease in sites of physiologic tracers' accumulation for SPECT and PET findings. Hybrid imaging in oncological applications has been very encouraging, indicating that these systems are suited for routine use in clinical practice. In fact, fused images provide additional information that improves diagnostic accuracy and impacts on patient management.

Diagnostic Imaging↗
PubMed2005

Estimation of transverse plane pelvic rotation using a posterior-anterior radiograph.

STUDY DESIGN: Experimental and analytical study of transverse plane pelvic rotation. OBJECTIVES: To determine how pelvic rotation projected onto the transverse plane relates to coronal plane anatomic landmark location. SUMMARY OF BACKGROUND DATA: Current spine deformity instrumentation may be used to apply transverse plane loads to the spine that may be transmitted to regions not included in the instrumentation, including the pelvis. METHODS: An anatomically correct, sawbones model of an adult female pelvis was marked with lead shot at prominent radiographic landmarks, rotated at different angles in the sagittal, transverse, and coronal planes, and left/right (L/R) ratios of the medial-lateral distances between similar landmarks determined. An analytical equation was also derived to determine the degree of rotation in the transverse plane, using medial-lateral and anterior-posterior distances between same landmarks. RESULTS: The L/R ratio for the coronal plane distance between the inferior ilium at the sacro iliac joint (SI) and anterior superior iliac spine (ASIS), the SI-ASIS measurement, proved the most reliable of the four ratios studied to determine the extent of pelvic rotation in the transverse plane. Assuming the pelvis is symmetric, the most important factor is location of the compared landmarks. A long distance between the landmarks in both the coronal and transverse plane and a large angle between the line joining the two landmarks and the coronal plane of the pelvis, as viewed in the transverse plane, are best. Transverse plane pelvic rotation up to 20 degrees is accurately reflected nearly linearly by L/R SI-ASIS ratios. CONCLUSIONS: Bony pelvis landmarks visible on coronal plane radiographs can be used to estimate transverse plane pelvic rotation, but precise conversion to degrees rotation requires additional information on specific patient pelvic morphology.

Adult↗
PubMed1993

A survey of different high resolution visualization modes of a volumetric object with applications.

In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.

Arachnoid Cysts↗
PubMed1999

Ultrasound-guided internal jugular venous cannulation in infants: a prospective comparison with the traditional palpation method.

BACKGROUND: Percutaneous cannulation of the internal jugular vein in infants is technically more difficult and carries a higher risk of carotid artery puncture than in older children and adults. In this prospective study, the authors tested their hypothesis that using an ultrasound scanner would increase the success of internal jugular cannulation and decrease the incidence of carotid artery puncture in infants. METHODS: After approval from the institutional review board and receipt of written informed parental consent, 95 infants scheduled for cardiac surgery were randomized prospectively into two groups. In the landmarks group, the patients' internal jugular veins were cannulated using the traditional method of palpation of carotid pulsation and identification of other anatomic landmarks. In the ultrasound group, cannulation was guided using an ultrasound scanner image. The cannulation time, number of attempts, success rate, and incidence of complications were compared for the two groups. RESULTS: There were no significant differences between the two groups with regard to weight, age, and American Society of Anesthesiologists physical status classification. The success rate was 100% in the ultrasound group, with no carotid artery punctures, and 77% in the landmarks group, with a 25% incidence of carotid artery punctures. Both differences were significant (P > 0.0004). The cannulation time was less, the number of attempts was fewer, and the failure rate was significantly lower in the ultrasound group than in the landmark group. CONCLUSION: Ultrasonographic localization of the internal jugular vein was superior to the landmarks technique in terms of overall success, speed, and decreased incidence of carotid artery puncture.

Carotid Artery Injuries↗
PubMed2006

Three-dimensional US of the fetus: volume imaging.

PURPOSE: To retrospectively compare the rapidity, efficiency, and accuracy of three-dimensional (3D) and two-dimensional (2D) ultrasonography (US) for complete anatomic survey in fetuses at 17-21 weeks of gestation. MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was waived, and the study was HIPAA compliant. Fifty consecutive women undergoing fetal anatomic survey at 17-21 weeks of gestation formed the study cohort. After standard 2D US was performed by one of eight sonographers, the same sonographer also obtained five 3D volumes to encompass the entire fetal anatomy. Three physicians interpreting the scans independently evaluated the completeness of the examination and time needed to read the scans, comparing the standard 2D method with the 3D volume reconstruction technique. The paired t test was used to compare biparietal diameter (BPD), femur length, and performance times between the 3D measurements and the 2D measurement. The t test was used to compare fetal anatomy according to volume angle. Differences were significant when P < .05. RESULTS: Mean time to perform 2D US was 19.6 minutes per examination, whereas mean time to perform complete 3D volume acquisition was 1.8 minutes. Mean times needed to interpret 3D images and measure the BPD and femur were 5.53, 4.79, and 5.34 minutes for the three interpreting physicians. Compared with complete fetal surveys performed with 2D US, individual fetal anatomic landmarks (except for fetal arms and cavum septum pellucidum) were identified more than 94% of the time by using 3D US. Grouping anatomic views by region, the heart, head, extremities, and abdominal views were completely seen in 88%, 90%, 90%, and 95% of patients, respectively. No significant difference was seen between the three physicians regarding completeness of the 3D examinations (P = .7). One fetus had multiple anomalies, with 3D volumes identified as abnormal by all three physicians. Overall, 74% of 3D BPD measurements were within 1 mm of the 2D measurements, and 64% of 3D femur measurements were within 1 mm of the 2D measurements. CONCLUSION: The standard fetal anatomic survey can be performed in less than 2 minutes with 3D volume US, and the volumes can be interpreted in 6-7 minutes, compared with a mean of 19.6 minutes to perform standard 2D US.

Adult↗
PubMed1996

Landmark-based registration and measurement of magnetic resonance images: a reliability study.

We report a magnetic resonance imaging (MRI) study in a large number of subjects that examines various analytic techniques for anatomical landmark information. The initial issue involved interrater reliability in locating landmarks along the midsagittal plane. Another issue dealt with using landmarks to register (linear) individual scans for subsequent analyses or more sophisticated registration techniques. We next explore the use of interlandmark distances as indices of brain size. Twenty-seven landmarks were chosen from the midsagittal slice of 101 abnormal subjects. Interrater reliability estimates on a subset of the scans were excellent overall. Rotating to anterior-posterior commissure points was the best of the tested two-point registrations, although an average angular rotation was better. Reliability and validity for landmark-derived measures of size were excellent. Landmark-based analyses offer opportunities to explore shape and size questions, although they are not appropriate for addressing all questions. Under specific conditions, landmark data can be generated quickly and accurately.

Adolescent↗
PubMed1984

[Distribution of trabecular microfractures in the proximal femur--with the epiphyseal scar as a landmark].

The distribution of the trabecular microfractures in normal human proximal femora was investigated to see whether they were related to the femoral neck fracture of the elderly. In this study the epiphyseal scar was employed as an anatomical landmark in the proximal femur, since the authors' observation suggested that it remained throughout life and was located in constant connection with the margin of the articular cartilage. The medial aspect of the proximal femur was divided into three anatomical zones, which were called epiphyseal, subepiphyseal and subcapital ones, respectively. There were two areas in which trabecular microfractures concentrated; one was about the lateral end of the epiphyseal scar and another the subepiphyseal zone. Few microfractures were noted on the principal compressive trabeculae. A femoral neck fracture of the elderly usually provides a fracture line running from the lateral end of the epiphyseal scar down to the subcapital zone. Thus the fracture takes place just within the area of concentration of trabecular microfractures laterally, whereas it passes caudad to the medial group of microfractures. The authors hypothesize that the trabecular microfractures arising about the lateral end of the epiphyseal scar may have an etiological significance for the femoral neck fracture, in contrast that those in the subepiphyseal zone may not.

Adult↗
PubMed1997

Glabellar approach: simplified midline anterior skull base approach.

As a simplified microsurgical technique for lesions at the midline anterior skull base, a glabellar approach through a small incision (5 cm) between the eyebrows crossing the nasion was developed in four cadaver dissections. To determine the ideal positioning of the patient, the angle of the surgical trajectory was measured in the sagittal plane. In an effort to make an operation simple and accurate through this limited exposure, measurements were made in distance from the midline nasion to various intradural structures. Average distance from the midline point of the nasion (MPNa) to the midline of the tuberculum sella was 6.37 +/- 0.29 cm, 6.98 +/- 0.26 cm to the midline of the optic chiasm, and 8.00 +/- 0.11 to the lamina terminalis. In addition, measurements to other various anatomical landmarks were made. The angle of the line drawn from the MPNa to the midline of the tuberculum sella was 5.2 +/- 1 degrees against a line drawn between the lateral canthus and the tragus (LC-T) in the sagittal plane. Based upon this study, the positioning of the patient's head would be better if the LC-T line is positioned at 25 degree extension when the operating microscope is set at 20 degree inclination. Within 6 to 8 cm in depth from the MPNa, important landmarks are exposed without brain retraction. If surgical instruments are marked with ruler calibration, the depth of the surgical instruments will suggest the anatomical location. This glabellar approach has been used in three patients successfully. A brain retractor was not necessary and not used during the operations. This technique provides key exposures to the midline anterior skull base.

Adult↗
PubMed2003

Landmark detection in the chest and registration of lung surfaces with an application to nodule registration.

We developed an automated system for registering computed tomography (CT) images of the chest temporally. Our system detects anatomical landmarks, in particular, the trachea, sternum and spine, using an attenuation-based template matching approach. It computes the optimal rigid-body transformation that aligns the corresponding landmarks in two CT scans of the same patient. This transformation then provides an initial registration of the lung surfaces segmented from the two scans. The initial surface alignment is refined step by step in an iterative closest-point (ICP) process. To establish the correspondence of lung surface points, Elias' nearest neighbor algorithm was adopted. Our method improves the processing time of the original ICP algorithm from O(kn log n) to O(kn), where k is the number of iterations and n the number of surface points. The surface transformation is applied to align nodules in the initial CT scan with nodules in the follow-up scan. For 56 out of 58 nodules in the initial CT scans of 10 patients, nodule correspondences in the follow-up scans are established correctly. Our methods can therefore potentially facilitate the radiologist's evaluation of pulmonary nodules on chest CT for interval growth.

Algorithms↗
PubMed2006

Complete axillary dissection: a technique that still has relevance in contemporary management of breast cancer.

Axillary lymph node status is an important prognostic indicator for women with breast cancer and axillary dissection provides accurate information regarding nodal status. In addition, local control of axillary disease and allocation of adjuvant systemic therapy are dependent on appropriate axillary surgery. The survival benefit of an axillary dissection remains controversial. We describe a technique of complete axillary clearance that includes levels I, II and III. In our experience this technique is associated with no additional morbidity to patients and incurs minimal prolongation of operative time compared with a level II dissection. Other operative descriptions of axillary surgery generally do not adequately describe a method that clearly and consistently identifies the boundaries, anatomical landmarks and neurovascular structures that traverse the axilla. This technique, with relative ease, allows the identification and preservation of these structures in their original anatomical planes and avoids the division of the pectoralis minor muscle. The assumption that routine level III axillary clearance, as opposed to level I or level II dissection, is associated with greater morbidity warrants further evaluation. No well-conducted randomized trials have addressed this issue.

Axilla↗
PubMed1995

Quadrant anatomy of the articular pillars (lateral cervical mass) of the cervical spine.

Knowledge of the relevant anatomy is important when developing a strategy for introducing screws into the lateral masses to secure internal fixation devices. This paper defines key bony landmarks and their relationship to critical neurovascular structures and identifies a location for safe placement of cervical articular pillar (lateral mass) screws. Measurements of anatomical landmarks in 10 spines from human cadavers aged 61 to 85 years were made by caliper and a metric ruler. Landmarks were the lateral facet line, rostrocaudal line, medial facet line, intrafacet line, and medial facet line-vertebral artery line. The average distances and ranges were recorded. Such great variance existed in measurements from spine to spine and within the same spine as to render averages clinically unreliable. Dissection revealed that division of the articular pillar into four quadrants leaves one, the superior lateral quadrant, under which there are no neurovascular structures; this may be considered the "safe quadrant" for placement of posterior screws and plates.

Aged↗
PubMedDate not supplied

Validation of an MRI/PET landmark registration method using 3D simulated PET images and point simulations.

Three-dimensional (3D) simulated PET images generated from MRI were used to validate a multimodality registration technique based on the identification of internal anatomical landmarks. In addition, point-based simulations were compared with registration datasets acquired over 3 yr of routine use of the technique. Registration errors were found to range from 1.0 mm at the brain centre to 2.8 mm in each dimension at the brain surface.

Computer Simulation↗
PubMed2002

Semi-automatic landmark detection in digital X-ray images of the spine.

Quantitative diagnosis of 3D scoliotic deformities depends on a number of dedicated measurements. Existing methods rely on the manual determination of a series of anatomical landmarks in X-ray images. We have developed an automatic method to alleviate the burden of this tedious task. Our method looks for a compromise between local image information and global prior constraints and finds the most probable points using dynamic programming optimization. Remaining errors can be quickly corrected by effective user interaction. The first results are promising.

Humans↗
PubMed2002

A new rapid landmark-based regional MRI segmentation method of the brain.

BACKGROUND: Neurodegenerative and cerebrovascular diseases show a distinct distribution of regional atrophy and subcortical lesions. OBJECTIVE: To develop an easily applicable landmark-based method for segmentation of the brain into the four cerebral lobes from MRI images. METHOD: The segmentation method relies on a combination of anatomical landmarks and geometrical definitions. It is applied on the surface reconstruction of the MRI volume. The internal borders between the lobes are defined on the axial slices of the brain. The reliability of this method was determined from MRI scans of 10 subjects. To illustrate the use of the method, it was applied to MRI scans of an independent group of 10 healthy elderly subjects and 10 patients with vascular dementia to determine the regional distribution of white matter hyperintensities (WMH). RESULTS: The intra-rater relative error (and intra-class correlation coefficient) of the lobe segmentation ranged from 1.6% to 6.9% (from 0.91 to 0.99). The inter-rater relative error (and intra-class correlation coefficient) ranged from 1.4% to 5.2% (from 0.96 to 0.99). Density of WMH was significantly higher in all four lobes in VD patients compared to controls (p<0.05). Within each group, WMH density was significantly higher in frontal and parietal than in temporal and occipital lobes (p<0.05). CONCLUSION: This landmark based method can accommodate age and disease-related changes in brain morphology. It may be particularly useful for the study of neurodegenerative and cerebrovascular disease and for the validation of template-based automated techniques.

Aged↗