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PubMed1994

Validity of cephalometric landmarks. An experimental study on human skulls.

Cephalometric landmark validity (the difference between the estimated landmark and the true landmark) has surprisingly not previously been comprehensively evaluated, and no previous study has examined the validity of cephalometric angles and distances. The aim of this study was to investigate the validity of 15 commonly used skeletal and dental cephalometric landmarks, and the subsequent effects on 17 angles and distances. Small steel balls were glued on to 30 Chinese dry skulls to represent the true anatomical landmarks. The skulls were mounted in a purpose-designed skull holder and two cephalograms recorded of each skull, one with and one without the steel balls on the landmarks. Validity was expressed as the difference in the measurements between the assessments made with and without the steel ball markers. Measurements were made relative to X and Y co-ordinates which were constructed from reference points (steel balls) glued intracranially to the skulls. Seven out of the 10 skeletal landmarks and all five dental landmarks, were found to be non-valid along the X or the Y axes (P < 0.05). The standard deviations of the validity errors were large, being 1.0-2.5 mm, along at least one axis, for eight of the skeletal landmarks and three of the dental landmarks. Four of the cephalometric angles (SNA, SN/MnP, MxP/MnP, and LI/MnP) and three of the distances (N-Me, MxP-Me, and lower incisor edge to APg) were also found to be invalid (P < 0.05). The validity errors were greater for angles involving dental landmarks and for angles dependent on four landmarks compared to those dependent on three. The standard deviations of the validity errors for the skeletal angles ranged from 0.9 to 1.8 degrees, except for ANB (0.4 degrees), and for the dental angles from 3.2 to 5.8 degrees.

Adult↗
PubMedDate not supplied

Influence of limb positioning and measurement method on the magnitude of the tibial plateau angle.

OBJECTIVE: To evaluate the effect of limb positioning and measurement technique on the magnitude of the radiographically determined tibial plateau angle (R-TPA). STUDY DESIGN: In vitro study, R-TPA was determined by 6 blinded observers and image measurement software. ANIMALS: Five canine cadaver hind limbs. METHODS: The legs were positioned on a custom-made positioning device simulating a radiographic tabletop technique in lateral recumbency. True lateral positioning was defined by superimposition of femoral and tibial condyles on the radiographic projection. Radiographs were taken while the specimens were relocated in a proximal, distal, caudal, and cranial direction with respect to the radiographic beam. For each specimen, 25 different radiographic views were obtained and 6 blinded observers determined the radiographic TPA using 2 different methods. The conventional method used precise anatomic landmarks to determine the tibial plateau. To simulate osteoarthritic changes complicating identification of these landmarks, the tangential method estimated the tibial plateau as the tangent to the central portion of the tibial plateau. After periarticular soft tissue dissection the anatomic tibial plateau angle (A-TPA) was determined. The A-TPA and the R-TPA were compared. RESULTS: The R-TPA significantly decreased as limb position with respect to the X-ray beam changed from cranial proximal to caudal distal. The maximal mean radiographic R-TPA difference was 3.6 degrees with the first and 5.7 degrees with the second method. Regardless of the method used there was no significant difference between A-TPA and R-TPA in the true lateral position. In the peripheral positions, however, significant differences between anatomic and radiographic TPA were seen. CONCLUSIONS: Limb positioning influenced the radiographic appearance of the tibial plateau and the magnitude of the measured TPA. Cranial and proximal positioning of the limb relative to the X-ray beam leads to overestimation whereas caudal and distal positioning leads to underestimation of the TPA. CLINICAL RELEVANCE: True lateral positioning of the tibia defined by superimposition of the femoral and tibial condyles should be used for accurate TPA determination before tibial plateau leveling osteotomy.

Animals↗
PubMedDate not supplied

The ribs: anatomic and radiologic considerations.

The ribs are essential structures of the osseous thorax and provide information that aids in the interpretation of radiologic images. Techniques for making precise identification of the ribs are useful in detection of rib lesions and localization of lung lesions. The big rib sign and the vertical displacement sign can be used to differentiate the right and left ribs on lateral chest radiographs. The clavicle, the xiphoid process, and the sternal angle may be used as anatomic landmarks for rib counting on computed tomographic scans. For rib counting on lateral chest radiographs, the sternal angle or the 12th rib may be used. Anatomic rib variants include developmental deformities, cervical rib, and short rib and may mimic true rib diseases. Detection of thoracic deformities such as funnel chest (pectus excavatum) and barrel-shaped thorax requires an awareness of the strong correlation between the transverse appearance of the thorax and costal shape. Shadows around the rib cage (eg, rib companion shadows, sharp lines along the lower margin of the ribs, rib overlying shadows) may mimic pleural and extrapleural disease on frontal chest radiographs. It is imperative that the radiologist be familiar with normal rib anatomy, normal rib variants, and the radiologic appearance of the ribs to prevent misdiagnosis.

Humans↗
PubMed2007

Early detection of cancer recurrence: 18F-FDG PET/CT can make a difference in diagnosis and patient care.

Early detection of recurrence is clinically important and can improve the prognosis and survival of patients with cancer. CT, considered the primary method of investigation because of its low cost and widespread availability, provides high-resolution anatomic details but may underestimate the actual tumor burden by overlooking small tumor clusters in areas of distorted anatomy after treatment. 18F-FDG PET is an effective whole-body imaging technique that detects metabolic changes preceding structural findings. However, the specificity of PET is impaired by false-positive or equivocal results attributable to the lack of precise anatomic landmarks and to sites of increased 18F-FDG uptake of nonmalignant etiology. PET/CT provides fused images that demonstrate the complementary roles of functional and anatomic assessments in the diagnosis of cancer recurrence through the precise localization of suspected 18F-FDG foci and their characterization as malignant or benign. In addition to the accurate diagnosis and definition of the whole extent of recurrent cancer, PET/CT has an impact on patient management because it can assist in defining potential candidates for surgery for cure, planning the appropriate surgical or radiotherapy approach, and referring patients with unresectable disease to other therapeutic options.

Fluorodeoxyglucose F18↗
PubMed2002

Correlations between virtual endoscopy and otoendoscopy of the retrotympanum.

The aim of this study was to examine the anatomical landmarks of the retrotympanum using two different techniques, virtual endoscopy (VE) and fiberoptic endoscopy, and to correlate the results furnished by the two methods. Ten otosclerotic patients who were due to undergo stapedectomy were scanned using high-resolution spiral CT. Selected CT datasets were processed with Navigator 2.0 software to obtain virtual endoscopic views of the retrotympanum. Subsequently, during the surgical procedure, fiberoptic endoscopy was performed with 2.7-mm 0 degrees and 30 degrees rigid endoscopes. The ability of the two imaging methods to identify specific anatomical structures was then compared. In all cases the pyramidal eminence, pyramidal crest and sinus tympani were clearly identified in both VE images and otoendoscopy recordings, while fiberoptic endoscopy seemed to be less satisfactory than VE for studying the facial sinus, sinus of Proctor and fossula of Grivot. The two techniques proved to be equally sensitive for visualizing the ponticulus and subiculum, while the stapedius tendon could be visualized only by means of fiberoptic endoscopy. Overall, VE imaging appears promising for rendering important anatomical details of the retrotympanum, allowing identification of osseous landmarks and exploring recesses that are difficult to visualize via otoendoscopy.

Ear, Middle↗
PubMed1987

Where is the gray line?

The gray line is a well-known surface anatomic landmark used by surgeons in the repair of lacerations involving the lid margin. To the best of our knowledge, no description of any deep or superficial anatomic counterpart of the gray line has been previously reported. We examined block resections of 51 eyelids histologically following localization of the gray line. The visualized gray line was consistently seen to correspond histologically to the most superficial portion of the orbicularis muscle, known as the muscle of Riolan. We comment on changes in gray line morphology with lid movement, and we advance a hypothesis to explain its "gray" color.

Eyelids↗
PubMed2000

Axilloscopy and endoscopic sentinel node detection in breast cancer patients.

BACKGROUND: Sentinel node biopsy is a promising technique that allows the axillary status of breast cancer patients to be predicted with high accuracy. Reducing false negative results remains a major challenge for the improvement of this procedure. Furthermore, new techniques are required to achieve axillary clearing with less morbidity in cases of unsuccessful mapping or multicentric carcinoma. We analyzed whether axilloscopy and endoscopic sentinel node biopsy is a feasible procedure for visualization of the axillary space and resection of the sentinel node using endoscopic techniques. METHODS: Following blue dye-guided lymphography and liposuction of the axillary fat, endoscopic axillary sentinel node biopsy was performed in 35 breast cancer patients. We then assessed the exposure of anatomical landmarks, the detection rate of the sentinel node, the false negative rate, and the accuracy of consecutive axillary clearing. RESULTS: In almost every case, an excellent anatomical orientation was achieved. The detection rate for the sentinel node was 83.3%. In one case, the sentinel node did not reflect the status of the residual axilla. A mean number of 17.1 lymph nodes was harvested at consecutive axillary clearing. CONCLUSIONS: Axilloscopy and endoscopic sentinel node biopsy, following liposuction of the axillary fat, is a feasible procedure that allows identification and minimally invasive resection of the sentinel node with high accuracy. The endoscopic approach might help to minimize the pitfalls of sentinel node biopsy by visualizing the axillary space. In future, it may become a technique that enables minimally invasive axillary clearing when complete lymphadenectomy is required.

Adult↗
PubMed2005

Reliable manual segmentation of the frontal, parietal, temporal, and occipital lobes on magnetic resonance images of healthy subjects.

BACKGROUND: It is a challenge to reliably measure the lobar volumes from magnetic resonance imaging (MRI) data. OBJECTIVE: Description of a landmark-based method for volumetric segmentation of the brain into the four cerebral lobes from MR images. METHOD: The segmentation method relies on a combination of anatomical landmarks and geometrical definitions. The first step, described previously, is a segmentation of the four lobes on the surface of the brain. The internal borders between the lobes are defined on the axial slices of the brain. The intra- and inter- rater reliability was determined from the MRI scans of a group of 10 healthy control subjects measured by 2 independent raters. RESULTS: The intra-rater relative error (and intra-class correlation coefficient) of the lobar volume measures ranged from 0.81% to 3.85% (from 0.97 to 0.99). The inter-rater relative error (and intra-class correlation coefficient) ranged from 0.55% to 3.09% (from 0.94 to 0.99). CONCLUSION: This technique has been shown to have high intra- and inter-rater reliability. The current method provides a method to obtain volumetric estimates of the 4 cerebral lobes.

Aged↗
PubMed1991

The dynamics of compartmentalization of embryonic muscle by extracellular matrix molecules.

In order to delineate the role of proteoglycans in muscle development, the immunohistological localization of glycosaminoglycans and proteoglycan core proteins was studied in embryonic chick leg at Hamburger-Hamilton stages (St.) 36, 39, 43, and 46, and at 2 weeks posthatching. A specific anatomical landmark was chosen (the junction between the pars pelvica and the pars accessoria of the flexor cruris lateralis muscle) in order to ensure the study of anatomically equivalent sites. Frozen cross sections were immunostained with monoclonal antibodies to chondroitin-4-sulfate, chondroitin-6-sulfate, dermatan sulfate, and keratan sulfate glycosaminoglycans; to the core proteins of muscle/mesenchymal chondroitin sulfate proteoglycan, dermatan sulfate proteoglycan, and basement membrane heparan sulfate proteoglycan; and to laminin and tenascin. Extracellular matrix zones corresponding to the endomysium, perimysium, epimysium, basement membrane, and myotendinous junction each show characteristic immunostaining patterns from St. 36 to St. 46 and have unique matrix compositions by St. 46. In some cases, there is a sequential or coordinate expression of epitopes, first in the epimysium, then the perimysium, and last in the endomysium. Dermatan sulfate proteoglycan is detected in the epimysium at St. 36, in the perimysium at St. 39 (there is no perimysium structure at St. 36), and is not detected in the endomysium until St. 43. A putative mesenchymal proteoglycan core protein (reactive to the monoclonal antibody MY-174) is detected at St. 39 in both epimysium and perimysium, but is not detected in the endomysium until St. 43. Keratan sulfate antibody immunostains epimysium at St. 39 and perimysium at St. 46, but is never detected in the endomysium. Some epitopes are expressed independently in each of the extracellular matrix zones: antibody to tenascin stains only a subset of the epimysium, at the myotendinous junction; and heparan sulfate proteoglycan and laminin are detected only in the endomysium. Between St. 36 and St. 39, the muscle/MY-174-reactive proteoglycan core protein staining decreases in intensity in the endomysium and becomes positive in the epimysium and perimysium. An inverse relationship is found between (1) the disappearance of muscle/MY-174-reactive proteoglycan core protein staining at the surface of myotubes from St. 36 to St. 39 and (2) the infiltration of laminin and heparan sulfate proteoglycan staining encompassing groups of myotubes (St. 36) to circumferential staining of all myotubes (St. 39).(ABSTRACT TRUNCATED AT 400 WORDS)

Aggrecans↗
PubMedDate not supplied

[Calcified stylo-hyoid ligament. Its role in the diagnosis of laterocervical pain].

The calcification of the stylo-hyoid ligament is very often accidentally discovered during a panorex examination. Sometimes it is responsible of lateral and cervical pain spreading to the oral cavity and the maxilla. This anatomic landmark results in man from the more or less complete ossification of the hyo-branchial system due to the persistence of the Reichert cartilage. The anatomical environment of the ossified stylo-hyoid ligament is very rich in thick blood vessels and cranial nerves and can lead after compression or irritation to: vascular pain of the external carotid artery, recurrent syncopes by irritation of the carotid sinus, pain in the tonsils, phonation and swallowing troubles, referred pain in the temporo-mandibular joints. The standard clinical and radiographic examination will help to establish the differential diagnosis. The treatment is either non surgical, by cutaneous infiltration of local anesthetic or surgical, by the removal through the oral cavity of the calcified stylo-hyoid ligament.

Adult↗
PubMed2003

Analyzing the neocortical fine-structure.

Cytoarchitectonic fields of the human neocortex are defined by characteristic variations in the composition of a general six-layer structure. It is commonly accepted that these fields correspond to functionally homogeneous entities. Diligent techniques were developed to characterize cytoarchitectonic fields by staining sections of post-mortem brains and subsequent statistical evaluation. Fields were found to show a considerable interindividual variability in extent and relation to macroscopic anatomical landmarks. With upcoming new high-resolution magnetic resonance imaging (MRI) protocols, it appears worthwhile to examine the feasibility of characterizing the neocortical fine-structure from anatomical MRI scans, thus, defining neocortical fields by in vivo techniques. A fixated brain hemisphere was scanned at a resolution of approximately 0.3 mm. After correcting for intensity inhomogeneities in the dataset, the cortex boundaries (the white/grey matter and grey matter/background interfaces) were determined as a triangular mesh. Radial intensity profiles following the shortest path through the cortex were computed and characterized by a sparse set of features. A statistical similarity measure between features of different regions was defined, and served to define the extent of Brodmann's Areas 4, 17, 44 and 45 in this dataset.

Aged↗
PubMed2007

Single-photon emission computed tomography/computed tomography in abdominal diseases.

Single-photon emission computed tomography (SPECT) studies of the abdominal region are established in conventional nuclear medicine because of their easy and large availability, even in the most peripheral hospitals. It is well known that SPECT imaging demonstrates function, rather than anatomy. It is useful in the diagnosis of various disorders because of its ability to detect changes caused by disease before identifiable anatomic correlates and clinical manifestations exist. However, SPECT data frequently need anatomic landmarks to precisely depict the site of a focus of abnormal tracer uptake and the structures containing normal activity; the fusion with morphological studies can furnish an anatomical map to scintigraphic findings. In the past, software-based fusion of independently performed SPECT and CT or magnetic resonance images have been demonstrated to be time consuming and not useful for routine clinical employment. The recent development of dual-modality integrated imaging systems, which provide SPECT and CT images in the same scanning session, with the acquired images co-registered by means of the hardware, has created a new scenario. The first data have been mainly reported in oncology patients and indicate that SPECT/CT is very useful because it is able to provide further information of clinical value in several cases. In SPECT studies of abdominal diseases, hybrid SPECT/CT can play a role in the differential diagnosis of hepatic hemangiomas located near vascular structures, in precisely detecting and localizing active splenic tissue caused by splenosis in splenectomy patients, in providing important information for therapy optimization in patients submitted to hepatic arterial perfusion scintigraphy, in accurately identifying the involved bowel segments in patients with inflammatory bowel diseases, and in correctly localizing the bleeding sites in patients with gastrointestinal bleeding.

Abdomen↗
PubMed1996

Tributaries of the human and canine coronary sinus.

The coronary sinus is an anatomic landmark and conduit for many diagnostic and therapeutic procedures. We studied 40 human and 40 canine coronary sinuses of the heart in order to ascertain various functional anatomic features of the coronary sinus and its tributaries. We performed a comparative analysis of human and canine cardiac veins. We also studied the formation, tributaries, length, diameter and the ostium of the coronary sinus. The tributaries of the coronary sinus were highly variable in human and dog. The main and constantly present tributaries of both the human and canine coronary sinus were the great and the middle cardiac veins. We also found a rare case of a small cardiac vein connecting two cardiac venous systems--the coronary sinus and its tributaries and the anterior cardiac veins. In two cases we found a common trunk of the small cardiac vein and middle cardiac vein which opened into the coronary sinus. An intramyocardial course of the anterior interventricular vein was found in 2 cases and in 1 case the vein curved twice around the anterior interventricular branch of the left coronary artery. The Thebesian and Vieussens valves and ostial valves of other cardiac veins were also found.

Animals↗
PubMed2003

Petrous anatomy for middle fossa approach.

OBJECTIVE: The objective was to describe the relationship of anatomical landmarks required for the middle fossa approach to lesions of the petrous apex and internal auditory canal (IAC). Landmarks for safe identification of the IAC are defined, as are two zones (safe zones I and II) anterior and posterior to the IAC. STUDY DESIGN: Temporal bone anatomical study. METHODS: Ten temporal bones underwent high-resolution computed tomography followed by wet bench dissection. A set of 39 different distances between vital structures was measured, where possible, from both radiology films and under the microscope. Mean, median, minimum, and maximum measurements of all distances were determined. Angular measurements were made using a specially designed instrument. RESULTS: Measurements were made in an anatomical position to mimic the middle fossa surgical technique. Measurements are presented for the superior surface of the temporal bone from the sigmoid sinus and inner table to vital structures, from the anterior and posterior petrous apex, and from the IAC. CONCLUSIONS: Petrous apex anatomical knowledge is required for the safe middle fossa approach to the IAC and petrous apex. Two safe zones are defined that should prevent damage to the cochlea and the superior semicircular canal.

Cephalometry↗
PubMed2002

Dorsalis pedis arterial pulse: palpation using a bony landmark.

INTRODUCTION: The unreliability of the pulse examination of the foot has primarily been due to variability of technique between examiners. Whereas the groove between the medial malleolus and the Achilles tendon more readily defines the location of the posterior tibial pulse, the location of the dorsalis pedis pulse remains vague. In this paper a novel method of locating the dorsalis pedis pulse by physical examination is described. METHODS: Forty one consecutive patients admitted to a general surgery service of a tertiary medical centre within a two month period were examined. Using the dorsal most prominence of the navicular bone as a landmark, the distance to the dorsalis pedis pulse in bilateral lower extremities was measured by palpation and compared to Doppler ultrasound. Measurements were confirmed by two separate examiners blinded to each others' results. RESULTS: The dorsalis pedis artery was palpable in 78% of extremities and present by Doppler ultrasound in 95%. The location of the left dorsalis pedis artery was a mean (SD) 9.8 (1.4) mm by palpation and 11.1 (2.1) mm by Doppler ultrasound from the dorsal most prominence of the navicular bone. The right dorsalis pedis artery was 10.4 (3.4) mm by palpation and 11.5 (0.7) mm from the dorsal most prominence of the navicular bone. No significant differences in location of the dorsalis pedis artery were observed bilaterally between Doppler ultrasound and palpation; No significant differences were observed comparing contralateral dorsalis pedis arteries nor any differences between the examiners' results. CONCLUSION: The dorsal most prominence of the navicular bone provides a bony landmark to readily locate the dorsalis pedis artery. Reliability of the examination may be increased as to the patency of the dorsalis pedis artery by using this dependable anatomic landmark.

Adult↗
PubMed1999

[The architectural balance of the face: a 3D cephalometric concept].

The use of the c2000 software led us to develop a new 3D cephalometric construction, based on the selection on the axial CT Scans of 8 anatomical landmarks and of teeth, all of which were situated along the trigeminal neuro matriciel facial growth axes. The analysis of this construction is based on the use of an original mathematical tool in biology: the axes of inertia. Using the selection of both mental foramen, both infra and supra orbital foramen and the head of both malleus, the C 2000 software creates a geometrical construction called: "the maxillo-facial frame", as well as, a 3D cephalometric analysis: angles, distances, areas, volumes center of gravity and axes of inertia. Using the selection of teeth, the C 2000 software calculates the axes of inertia of each tooth or of groups of teeth. The use of the axes of inertia allow us to create of a hierarchy of anatomical levels the teeth, the half arches, the arches, both arches and the maxillo-facial frame. In addition, for each of these anatomical levels, the axes of inertia create a 3D landmark which allows the calculation of the orientation of each of these elements in relation to the others. The study of 28 orthomorphic people using this analysis revealed the existence of a maxillo-facial balance that is unique for each individual.

Adolescent↗
PubMed2004

Indications and limitations of intraoperative navigation in maxillofacial surgery.

PURPOSE: Although primarily developed for neurosurgical application, intraoperative navigation has gained acceptance even in maxillofacial surgery with an increasing field of indications. We want to demonstrate our clinical experiences, focusing on the indications and limitations of intraoperative navigation. MATERIALS AND METHODS: In our department, the navigation system VectorVision (BrainLAB, Heimstetten, Germany) is used. The accuracy of this referencing method, consisting of a cortical fixed reference system and surface scanning, was checked by anatomic landmarks. Surgical treatment of 20 patients was performed with the help of the navigation system. RESULTS: The VectorVision system proved to be a useful supplement during the surgical exploration of complex anatomic regions. However, resolution of imaging data sets, errors of image fusion, and discrepancies during referencing increased the inaccuracy before surgery. The main problem was the topographic changes caused by surgery, resulting in discrepancies between the preoperative image data and the surgical site. In one case suffering from a meningioma extending to the neck, topography was changed by surgery making navigation inaccurate. CONCLUSION: Generally, a promising field for intraoperative navigation systems were small surgical approaches allowing only limited exposure. From our point of view, additional promising indications include vast tumors or recurrent tumors because of altered anatomy with lost landmarks during surgery. The same was the case of patients suffering from plexiform neurofibroma caused by neurofibromatosis type I. Further, intraoperative navigation was helpful to determine the position of foreign bodies during imaging, making the intraoperative location easier.

Adult↗
PubMed2005

Cup alignment error model for total hip arthroplasty.

Almost all computer-assisted orthopaedic surgery systems that rely on the anterior pelvic plane definition, such as in computed tomography and magnetic resonance image-based, fluoroscopy-based, and nonimage total hip replacement approaches, are derived from identifying two pairs of pelvic bony landmarks: anterior superior iliac spines and the pubic tubercles. Although these systems strive to achieve cup alignment accuracy of approximately 1 degree, even a minor failure to correctly identify these anatomic landmarks can lead to higher inaccuracies in the final cup alignment. This study shows how to examine the effects of these inaccuracies on the final acetabular cup implant orientation during total hip replacement by generating a kinematic model, which then is simulated. Simulation results indicate that, for example, a total error of 4 mm in measuring the anterior superior iliac spine and the pubic tubercles would result in a final cup orientation of 47 degrees and 27 degrees in abduction and version respectively, resulting in a 2 degrees abduction error and 7 degrees error in version when targeting 45 degrees abduction and 20 degrees version results. These calculations can be repeated for any error values.

Acetabulum↗