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 451 records · Page 25Linked to original sources
PubMed2002

Does ultrasound imaging before puncture facilitate internal jugular vein cannulation? Prospective randomized comparison with landmark-guided puncture in ventilated patients.

OBJECTIVE: To investigate whether prepuncture ultrasound evaluation of vascular anatomy facilitates internal jugular vein cannulation compared with landmark-guided puncture. DESIGN: Prospective randomized study. SETTING: Single community hospital. PARTICIPANTS: Adult patients undergoing general anesthesia (n = 240). INTERVENTIONS: The right internal jugular vein was cannulated using either anatomic landmarks or prepuncture ultrasound (3.75/7.5 MHz) guidance. In the landmark group, respiratory jugular venodilation was used as the primary landmark for locating the vein. Results of cannulation and the incidence of complications were compared. MEASUREMENTS AND MAIN RESULTS: Patients were randomly assigned to the ultrasound or landmark group. Respiratory jugular venodilation was identified in 188 patients (78.3%), in whom results of cannulation did not differ between the 2 techniques with respect to the venous access rate (cannulated at the first attempt: 83.5% in the landmark v 85.7% in the ultrasound group), the success rate (cannulated within 3 attempts: 96.9% v 95.6%), and the incidence of arterial puncture (1.0% v 3.3%). In the remaining 52 respiratory jugular venodilation-unidentified patients, the access rate (30.4% v 86.2%, p < 0.001) and the success rate (78.3 v 100%, p < 0.05) were significantly better in the ultrasound group, and no arterial puncture was recorded in the ultrasound group, whereas the incidence was 13.0% in the landmark group. The results were similar regardless of the ultrasound frequency used. CONCLUSION: Prepuncture ultrasound evaluation did not improve the result of right internal jugular vein cannulation compared with the respiratory jugular venodilation-guided approach. When the landmark was not observed, however, the prepuncture ultrasound guidance was helpful in facilitating the cannulation.

Adult↗
PubMed2000

Experience with various 3-dimensional navigation systems in head and neck surgery.

OBJECTIVE: To evaluate the benefits and difficulties encountered when using various 3-dimensional (3-D) navigation systems in head and neck procedures. DESIGN: Five different navigation systems were used for preoperative planning and intraoperative 3-D navigation in procedures at the paranasal sinuses, the frontal and lateral skull bases, and the petrous bone. INTERVENTION: Intraoperative 3-D localizing systems (position-sensitive mechanical arms, infrared cameras, etc) demand reliable patient fixation on the operating table. We achieved this by developing a noninvasive head holder. Other systems allow patient movements by using magnetic digitizing technology (ARTMA System) and sophisticated programming. RESULT: Having surpassed an initial learning curve, we now achieve an accuracy of 1 to 2 mm regularly. Especially in paranasal and frontal basal surgery, all navigation systems used provide valuable positioning information during surgery. In particular for revision or tumor surgery, decisive benefits resulted from use of these systems: shorter overall operation time; safer manipulation near delicate structures; and reliable identification of the skull base even in patients with bleeding, scarring, or missing anatomical landmarks. CONCLUSIONS: We performed approximately 250 operations with different systems and introduced navigation at the lateral skull base and the petrous bone with mechanical, optic, and magnetic digitizers. In these anatomical areas, navigation was used successfully; the technical challenge is greatest at the lateral skull base, however.

Endoscopes↗
PubMed2002

McBurney's point: are we missing it?

A prospective study of 100 post-evacuation barium enemas was done. Films were centered at McBurney's point, with an opaque skin marker at that point. Analysis of these revealed that in only one case (1%) was the base of the appendix at McBurney's point. In 67% it was cephalic and in 32% it was caudal to this point. The limitations of McBurney's point as an anatomical landmark should be recognized. This needs to be highlighted in teaching anatomy, especially to surgical trainees. Planning and choice of surgical incisions should be based on an understanding of these anatomical variations since McBurney's original description was clinical rather than anatomical.

Adolescent↗
PubMed1990

The petrous carotid artery: anatomic relationships in skull base surgery.

Advanced transcranial lesions may be successfully resected through a variety of contemporary skull base approaches. The identification and isolation of the internal carotid artery throughout its petrous course is essential in most of these surgical techniques. Anatomic landmarks normally used to identify this vital structure, however, may be severely distorted by tumor involvement or previous operative dissection. In an effort to define surgical landmarks that may be used in the identification of the petrous carotid artery, histologic sections of 100 temporal bones from adults were examined and microscopic measurements were recorded from the anatomic dissection of 10 fresh cadaver halfheads. On the basis of these studies, structures we have found useful in identification of the vertical petrous carotid artery during lateral skull base approaches include the: base of the styloid process, bony vascular crest, basal turn of the cochlea, medial wall of the eustachian tube, and the cochleariform process. Identification of the horizontal segment can be achieved by the preliminary delineation of the middle meningeal artery, greater petrosal nerve, tensor tympani muscle, mandibular and maxillary divisions of the trigeminal nerve, and the eustachian tube. Specific anatomic relationships with associated measurements are detailed and correlated with selected, illustrative cases.

Carotid Arteries↗
PubMed1994

Measurement of ultrasound biomicroscopy images: intraobserver and interobserver reliability.

PURPOSE: To evaluate intraobserver and interobserver reproducibility of measurement of images obtained during ultrasound biomicroscopy. METHODS: Four anterior segment images of four normal patients were obtained by a single examiner. The measurements of three independent observers were compared to assess interobserver reproducibility in quantifying the images. Thirteen different anterior segment parameters were measured by each observer on each image. Intraobserver and interobserver reproducibility of measurement were assessed by calculating the coefficient of variation for each individual observer and by using the F test to detect a difference among observers. RESULTS: Intraobserver reproducibility was high. Interobserver reproducibility for the measured parameters varied considerably and was affected by subjective interpretation of visualized anatomic landmarks. CONCLUSIONS: The optimal parameters for quantitative ultrasound biomicroscopy require refinement. Measurements of alterable parameters are best measured presently by a single observer. Ultrasound biomicroscopy has the potential to elucidate anatomic relationships underlying much anterior segment disease, but caution in interpreting quantitative differences is warranted.

Anterior Eye Segment↗
PubMed1992

Sylvian fissure morphology and asymmetry in men and women: bilateral differences in relation to handedness in men.

The anatomy of the sylvian fissure in the human brain was studied to develop reliable criteria for anatomical landmarks of the posterior part of the fissure for use in its definition and measurement; to quantify right-left asymmetries in segments of the sylvian fissure; to assess whether any anatomical features are associated with hand preference (selected as one index of hemispheric functional asymmetry); and whether structure-function relationships are similar in men and women. A sample of 67 brain specimens (24 men and 43 women, mean age = 53 years) was studied postmortem (with the aid of dissection) from people who had been tested before death for detailed hand preference. Sylvian fissure anatomy in the human brain is very variable and no agreement exists as to the point of its posterior termination. The posterior ascending ramus, originating at the posterior bifurcation of the fissure, was found to be the continuation of the main limb of the sylvian fissure. Three segments of the sylvian fissure were defined and measured: anterior, horizontal, and vertical. The anterior segment showed no asymmetry; the horizontal segment was twice as large on the left side as on the right; and the vertical segment twice as large on the right. The two asymmetries counterbalanced each other, and overall asymmetry in the posterior region (horizontal plus vertical) was minimal. The basic asymmetry is in the position at which the fissure turns up, resulting in the different extent and position of the surrounding right and left parietal and temporal gyri and associated cytoarchitectonic regions. The possible embryological course of the asymmetry is discussed. Handedness correlated with anatomy of the sylvian fissure in men. In contrast to general expectation, hand preference was associated with a bilateral feature of morphology, and not with less asymmetry in non-right-handers. Men having consistent-right-hand preference had longer horizontal segments in both hemispheres compared to men not having consistent-right-hand preference. The direction and magnitude of asymmetry did not differ between the two male hand-preference groups. Since hand preference is an index of other motor and perceptual functions which are asymmetrically represented in the two hemispheres in gyri surrounding the sylvian fissure, it is suggested that anatomy of the sylvian fissure is related to functional asymmetries in men. A sex difference in structure-function relationship was observed. No association was found between hand preference and sylvian fissure anatomy in women.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain↗
PubMed1988

The functional anatomy of the human coronary sinus.

The human coronary sinus is an important part of the cardiac venous system that serves as an anatomic landmark as well as a conduit for diagnostic and therapeutic procedures. We studied 50 human coronary sinuses of hearts of normal and increased cardiac weight in order to ascertain various functional anatomic features of the coronary sinus and differences between hearts of normal and increased weight. In the hearts of normal weight (195 to 300 gm) the Thebesian valve covered the ostium of the coronary sinus an average of 41%, with complete coverage in 20%. The valve of Vieussens covered the origin of the coronary sinus an average of 59%. The average volume of the coronary sinus was 1.26 +/- 0.45 cc. In hearts of increased weight (365 to 675 gm), the Thebesian valve covered the ostium an average of 26% and the valve of Vieussens covered the origin of the coronary sinus an average of 56.5%. The average volume of the coronary sinus was increased to 1.76 +/- 0.73 cc (p less than 0.005). Thus knowledge of these functional anatomic features and the differences in hearts of increased cardiac weight allows for better utilization of the human coronary sinus for diagnostic and therapeutic purposes.

Adult↗
PubMed2001

Laparoscopic Roux-en-Y gastric bypass using the porcine model.

BACKGROUND: The laparoscopic Roux-en-Y gastric bypass (LRYGBP) may be performed using a variety of methods. The purpose of this study was to learn how to perform the Roux-en-Y gastric bypass operation laparoscopically, using a porcine model. MATERIALS AND METHODS: 11 domestic pigs (mean weight 47 kg) underwent LRYGBP. In 8 animals, a completely laparoscopic approach was attempted, while in 3 animals a hand-assist device was used. Techniques for anvil placement, pouch calibration, and limb-length measurement were evaluated. Animals were sacrificed at the end of the procedure, and operative results were recorded. RESULTS: The hand-assist device restored tactile feedback but obscured visualization. The gastrojejunostomy leak rate was 64%, and the jejunojejunostomy leak rate was 73%. Anvil placement using transgastric and transoral methods was feasible. Calibrating the pouch with a Baker's tube was more accurate than using anatomical landmarks. Measuring limb-lengths using Babcock clamps was reliable with practice. CONCLUSION: The frailty of the porcine small intestine may limit one's ability to achieve intact anastomoses. Despite the anatomic limitations, the porcine model was well-suited for skill development and evaluation of techniques for performing the LRYGBP operation.

Anastomosis, Roux-en-Y↗
PubMedDate not supplied

Malleable registration mask: application of a novel registration method in image guided sinus surgery.

Image-guided systems are becoming more widely used in endoscopic sinus and skull base surgery. All systems require initial registration to correlate the CT scan images to the patient's anatomy. Multiple registration techniques can be used. The ideal technique is one that is easy, reproducible, and provides the most accurate registration in the least amount of time. This study used an optical-based image-guided system (LandmarX) to test a unique mask registration technique and (compared it to a previously used anatomic registration technique. Twenty-one patients were scanned with the mask and underwent surgery. Registration was performed using both the registration mask and the anatomic landmarks. Mean registration error and time were recorded. Results are reported for 20 patients. Mean registration error for the mask technique was 0.96 mm and took a mean of 41 seconds. Anatomic registration error using five or six points resulted in a mean initial error of 2.08 mm and took 31.2 seconds. Mean final anatomic registration error was 1.53 mm, requiring reregistration of a mean of 4.6 points, and took 106 seconds. Statistically significant differences were obtained between the two techniques with regard to registration error and time to final registration. We found that the registration mask technique is a more reliable technique in ease, accuracy, and time of registration. This technique should be especially beneficial to the less experienced image-guided surgeon.

Female↗
PubMed1989

Anatomical considerations for mandibular anesthesia in patients with hemifacial microsomia.

Hemifacial microsomia is a congenital abnormality of the structures derived from the first and second branchial arches. The severity of this disorder is variable and affects the anatomical landmarks essential for establishing the proper pathway for needle insertion prior to deposition of the local anesthetic solution to attain regional mandibular anesthesia preparatory to dental procedures. This paper describes normal anatomical considerations for regional anesthesia in the mandibular arch, deviations in normal anatomy found in patients with hemifacial microsomia, the rationale for suggesting modifications to standard techniques for mandibular anesthesia in patients with this disorder, and presents ways for the dentist to achieve anesthesia (analgesia) on the affected side of the mandibular arch in patients with hemifacial microsomia.

Anesthesia, Dental↗
PubMedDate not supplied

Topographical variation of the human primary cortices: implications for neuroimaging, brain mapping, and neurobiology.

The relationships of the "primary" cytoarchitectonic neocortical fields, 17, 41, 3b, and 4 (Brodmann areas), to salient topographic landmarks have been reconstructed from serial histological sections in 20 human cerebral hemispheres (10 brains). Each of these architectonic fields is found to bear a characteristic relationship to a set of enframing anatomic landmarks, in particular, gyri, fissures, and sulci, that can be readily defined by MRI. Two classes of variability were found characteristic, at least to some extent, of each of the fields. Class 1 variability--variability that is not predictable from visible landmarks--was typical of the polar and for the cuneal and lingual extracalcarine distributions of field 17 and the distribution of field 4 upon the paracentral lobule. Class 2 variability--variability that is closely predictable from visible landmarks--is seen in the marked interindividual or interhemispheric variation in size or shape of a field and was found to be prominent for all four fields. Because of the prominence of class 2 variability, direct reference to the landmarks that frame these fields may be expected to be a more reliable basis for functional mapping than reference to a template or stereotactic coordinate-based system of reference to a standard or idealized brain.

Adolescent↗
PubMed1996

Combined Tc-99m MIBI and Tc-99m RBC for anatomic localization of ectopic mediastinal parathyroid adenomas.

Preoperative localization of abnormal parathyroid tissue in patients with persistent or recurrent hyperparathyroidism is recommended as a standard of care. A high percentage of these patients have ectopic tissue in the mediastinum. Tc-99m MIBI imaging alone for detection of ectopic parathyroid tissue in the mediastinum does not provide a sufficient number of anatomic landmarks, which makes communication regarding the exact location of any area of abnormal uptake difficult. We report the use of concomitant Tc-99m RBC and Tc-99m MIBI imaging for precise anatomic localization of ectopic mediastinal parathyroid tissue in 4 patients. It is thought that this combination of studies allows improved communication with referring physicians, surgeons, and radiologists for planning both surgical approach and correlative imaging studies. It is hoped that in the future this combination of studies may obviate the need for other imaging studies.

Adenoma↗
PubMed1984

Median nerve determinations: analysis of two techniques.

The objective of this study was to compare two techniques of obtaining median motor and sensory nerve determinants. One method utilized premeasured electrode placement, while the other used anatomic landmarks. It was postulated that increased accuracy could be achieved by more precise measuring techniques. The right median nerve in 50 able-bodied subjects was investigated. Each subject was tested by both anatomic and premeasured methods. Skin temperatures were maintained between 31C and 33C. Latencies were measured to onset and peak, and amplitudes were gauged from baseline to peak. Latency studies were evaluated. Results concluded that mean distal motor latencies, stimulating 8cm from active recording electrode, was 3.1msec +/- 0.4 and amplitude was 11.1mV +/- 3.0. Stimulating at distal wrist crease, mean latency was 2.6msec +/- 0.38 and amplitude was 11.3mV +/- 3.6. Sensory latencies to onset of response when stimulating 14cm from active ring electrode with reference 4cm distally were 2.1msec +/- 0.25. Sensory latency when stimulating at wrist crease and ring electrodes over proximal interphalangeal and distal interphalangeal joints was 2.1msec +/- 0.25 to onset and 2.8msec +/- 0.32 to peak and amplitude was 36.1 +/- 14.6. The authors concluded that there was no statistically significant difference in accuracy between the premeasured and anatomic methods.

Adolescent↗
PubMed2004

Invariant surface alignment in the presence of affine and some nonlinear transformations.

In this paper, we introduce a non-iterative geometric-based method to align 3D brain surfaces into standard coordinate system, which is based on a novel set of surface landmarks (e.g., inflection and/or zero torsion points residing on parabolic contours), which are intrinsic and are computed from the differential geometry of the surface. This is in contrast to existing methods that depend on anatomical landmarks that require expert intervention to locate--a very hard task. The landmarks are local and are preserved under affine transformations. To reduce the sensitivity of the landmarks to noise, we use a B-Spline surface representation that smoothes out the surface prior to the computation of the landmarks. The alignment is achieved by establishing correspondences between the landmarks after a sorting of the landmarks based on derived absolute invariants (volumes confined between parallelepipeds spanned by sets of the landmark point quadruplets). The method is tested for intra- and inter-brain alignments while entertaining affine, cubic and fourth-order polynomial nonlinear transformations using distance mapping as well as comparison with an expert alignment, and promising results are obtained. When comparing our automatic alignment with that of an expert we arrived at complete agreement for the more difficult case of partial alignment of sectional slab materials of five rats with an atlas (a whole brain of rat). This perfect alignment was only based on the surface structure for our procedure, whereas it was based on the staining and the external and internal structures for the expert.

Algorithms↗
PubMed1999

Biomechanics of the knee: methodological considerations in the in vivo kinematic analysis of the tibiofemoral and patellofemoral joint.

The purpose of this review article is twofold: to report on the use of intracortical pins to measure three-dimensional tibiofemoral and patellofemoral joint kinematics and highlight methodological concerns associated with this procedure. Tibiofemoral and patellofemoral kinematics has been extensively investigated using reflective markers attached to the surrounding soft tissue of the calf and thigh. However, surface markers may not adequately represent true anatomical locations and skin movement artefacts present the most critical source of measurement error. Consequently, knowledge about skeletal tibiofemoral kinematics is limited, in particular abduction-adduction and internal-external rotations. Considerable questions remain regarding what constitutes normal motion of the knee. A way to avoid the problem of surface markers is use invasive markers to directly measure skeletal motion. To date, many co-ordinate systems have been used to describe three-dimensional skeletal kinematics of the lower limb in vivo. They include helical axes, finite helical axes, instantaneous helical axes, and the joint co-ordinate system based on local anatomic landmarks. Although each method accurately describes the relative motion in 6 d. of f., the differences in how the motion is partitioned may account for the differences across investigations. Additionally, the problem of defining the anatomical co-ordinate system makes comparisons across subjects and studies difficult since subtle differences may be caused by small deviations in the anatomical reference alignment. Cross talk is also a primarily a concern. For joints that articulate principally about one axis, the primary flexion/extension that is registered will be cross-talked into ab/adduction and internal/external rotations.

Biomechanical Phenomena↗
PubMed1995

Digital portal image registration by sequential anatomical matchpoint and image correlations for real-time continuous field alignment verification.

Detection of radiotherapy field misalignments with electronic portal imaging devices requires the precise initial registration of the digital portal image with a reference image indicating the prescribed field alignment. Moreover, for real-time continuous detection this registration must be performed rapidly--arguably within 250 ms. The quality of this registration is sensitive to the ability of the user to accurately identify corresponding anatomical landmarks in the image pair. To improve the accuracy of the registration and, ultimately, that of the field misalignment measurement, we have developed a sequential digital portal image registration method using both user-identified anatomical matchpoints and image information. A first pass generates registration parameters from user-provided matchpoint coordinates and explicitly accounts for the uncertainty in matchpoint identification. The second pass uses both the initial registration parameters and image information to further improve the registration quality by maximizing cross correlations between segments of the image pair. As this registration method does not use massive matrix/vector computations common to other algorithms, it is inherently faster and well-suited for real-time field placement error detection. On a platform representative of those controlling many commercial electronic portal imaging devices (486 CPU), this algorithm registers portal images in times of less than 6 ms per matchpoint with errors of less than 2% in magnification, 0.5 degree in in-plane rotation, and less than 1 pixel dimension in in-plane translation. As the algorithm assumes a rigid-body geometry, it is sensitive to out-of-plane rotations. A quantitative analysis of this algorithm is presented, indicates its accuracy, and describes its sensitivity to out-of-plane rotations.

Algorithms↗
PubMed1992

Positional changes of the mandibular condyle assessed by three-dimensional computed tomography.

This investigation was designed to test the validity and reliability of three-dimensional computed tomography (3-D CT) for quantification of positional changes of the condyle in a laboratory model. The model consisted of a mounted dried human skull and a mandibular condyle attached to a micromanipulator. Controlled changes in condylar position were made and the condyle/fossa was imaged. Positional changes were measured by triangulation methods based on specific 3-D CT landmarks. The data were analyzed using descriptive statistics, analyses of variance to evaluate the sources of variability, and linear contrasts to evaluate the differences between observed and expected values. The results indicated that selection of appropriate anatomic landmarks for assessment of movement influences technique accuracy. The data also indicate that 3-D CT is most accurate in detecting inferior condylar movements. Lateral and posterior movements were assessed with less accuracy than the inferior positional changes. The clinical significance of these differences has yet to be determined.

Analysis of Variance↗