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PubMed1992

Anatomic importance of the retrofacial air tract.

The retrofacial air tract is a constant and relevant anatomic landmark for the temporal bone surgeon. By purposefully dissecting this space, one is able to safely identify the facial nerve, endolymphatic sac, and jugular bulb. The retrofacial air tract also provides access to the petrous apex. Forty temporal bones of varying degrees of pneumatization were dissected in order to study the retrofacial air tract. A well-developed air tract was easily identified in all specimens. We describe our anatomic findings and discuss the surgical relevance and important of the retrofacial air tract.

Ear, Inner↗
PubMed2006

Precision of landmark positioning on digitized models from patients with cleft lip and palate.

OBJECTIVE: To quantify the precision of landmark positioning on digitized casts of patients with unilateral cleft lip and palate. PATIENTS: Forty plaster models of newborns up to 8 months of age were selected from the archive of the Department of Orthodontics of the University of Heidelberg. MATERIAL AND METHOD: The plaster-cast models were digitized with a Micromeasure 70 three-dimensional laser scanner (Micromeasure, Bischoffen, Germany). The laser scanner used in this study operates with a precision of 0.15 mm on the x- and y-axes and 0.06 mm on the z-axis. In the intraobserver study, a single observer placed anatomical landmarks in four rounds, with at least 4 weeks between each round. In the interobserver study, four different observers each placed the same landmarks once. For the two different studies, an ideal location for each landmark was calculated by averaging the landmark positions of the four rounds or observers. The distance between each of the four landmark positions and the ideal landmark was measured. RESULTS: A 95% confidence interval for the landmark positioning error was calculated. For the intraobserver investigation, this error was 0.34 to 1.30 mm, and for the interobserver investigation it was 0.7 to 2.00 mm. CONCLUSION: Because both investigations displayed comparable error intervals, it was concluded that different observers could perform landmark positioning for the same studies.

Cleft Lip↗
PubMed1999

The AV junction region of the heart: a comprehensive study correlating gross anatomy and direct three-dimensional analysis. Part I. Architecture and topography.

There is little detailed knowledge of the architecture of the AV junction region, the cytoarchitecture of the AV node or of its atrial connections. In the present study, the gross anatomy and topography of intracardiac structures in 21 adult canine hearts were photographically compared in whole and dissected hearts and tissue blocks and serial histologic sections made in three orthogonal planes. There are seven major new findings: 1) A coronary sinus fossa exists at the crux of the heart. It separates the right medial atrial wall (MAW) superoposterior region from the left atrium, its floor is the coronary sinus, and it carries the medial atrionodal bundle and proximal AV bundle on its right wall. 2) The posterior MAW forms two isolated bridges of myocardium as it surrounds the coronary sinus ostium, is isolated from the sinus venarum with crista terminalis and interatrial septum-by the floor of the inferior vena cava, and the narrow bridges link the posterior atrial wall to the mid MAW. 3) The tendon of Todaro has both epicardial and endocardial exposures, terminates in the superoposterior MAW and its medial aspect is adjacent sequentially to the medial atrionodal bundle and proximal AV bundle. 4) Only ordinary myocardium contacts the anulus fibrosus. 5) The ventricular septum's shoulder is humped shape posteriorly, is completely overlaid by anular myocardium and the medial leaflet and is joined by struts of papillary muscle. 6) The membranous septum joins the anterior ventricular septum to the crista supraventricularis, forms part of the posterior noncoronary and right aortic valve sinus walls and encases the right bundle branch. 7) The specialized conduction tissues, the superior, medial and lateral atrionodal bundles, the proximal AV bundle, AV node, distal AV bundle and right bundle branch are subjacent to MAW epicardium outside the right atrium, share regular intracardiac relationships with topographic landmarks and the medial atrionodal bundle, terminal superior atrionodal bundle, the proximal AV bundle and AV node are aligned to the medial leg of Koch's triangle. Thus, atrial myocardium of the AV junction region is that of the MAW. The floor of the inferior vena cava forms a natural barrier to impulse transmission along the full extent of the posterior MAW. The specialized tissues are outside of the MAW. Anatomic landmarks form reliable topographic landmarks for the specialized AV junction region tissues. A knowledge of the association of the specialized conduction tissues with specific regions of the MAW is useful in localizing the tissues and along with the coronary sinus fossa provides several extracardiac approaches.

Animals↗
PubMed1999

MRI-Based topographic parcellation of human cerebral white matter.

We describe a virtually automatic comprehensive parcellation of the human cerebral central white matter, which is based upon T1-weighted MRI scans. The system, which is "rule-based," is developed from prior anatomic studies of the human brain and experimental studies of connectivity in animals as elaborated in the companion manuscript. Boundaries which delineate anatomic subregions of the white matter are computed from the geometric features of anatomic landmarks visible in the imaging data. The fiber systems of the central white matter are ordered topographically into three compartments, reflecting the inferred arrangements of principal neural systems pathways. These include an outer radiate (fibers principally radially aligned), an intermediate sagittal (fibers principally sagittally aligned), and deep bridging (fibers bridging hemispheres or cortex and deep structures) compartments. Each of these compartments is secondarily parcellated into smaller units to increase the anatomic specificity and spatial resolution of the system. The principal intended uses for this system of anatomic subdivision are for the volumetric characterization of forebrain white matter in normal and abnormal brains and for precision and specificity of localization in focal lesion-deficit correlation studies.

Adult↗
PubMed2001

Determination of ventilatory liver movement via radiographic evaluation of diaphragm position.

PURPOSE: To determine the accuracy of estimation of liver movement inferred by observing diaphragm excursion on radiographic images. METHODS AND MATERIALS: Eight patients with focal liver cancer had platinum embolization microcoils implanted in their livers during catheterization of the hepatic artery for delivery of regional chemotherapy. These patients underwent fluoroscopy, during which normal breathing movement was recorded on videotape. Movies of breathing movement were digitized, and the relative projected positions of the diaphragm and coils were recorded. For 6 patients, daily radiographs were also acquired during treatment. Retrospective measurements of coil position were taken after the diaphragm was aligned with the superior portion of the liver on digitally reconstructed radiographs. RESULTS: Coil movement of 4.9 to 30.4 mm was observed during normal breathing. Diaphragm position tracked inferior-superior coil displacement accurately (population sigma 1.04 mm) throughout the breathing cycle. The range of coil movement was predicted by the range of diaphragm movement with an accuracy of 2.09 mm (sigma). The maximum error observed measuring coil movement using diaphragm position was 3.8 mm for a coil 9.8 cm inferior to the diaphragm. However, the distance of the coil from the top of the diaphragm did not correlate significantly with the error in predicting liver excursion. Analysis of daily radiographs showed that the error in predicting coil position using the diaphragm as an alignment landmark was 1.8 mm (sigma) in the inferior-superior direction and 2.2 mm in the left-right direction, similar in magnitude to the inherent uncertainty in alignment. CONCLUSIONS: This study demonstrated that the range of ventilatory movement of different locations within the liver is predicted by diaphragm position to an accuracy that matches or exceeds existing systems for ventilatory tracking. This suggests that the diaphragm is an acceptable anatomic landmark for radiographic estimation of liver movement in anterior-posterior projections for most patients.

Diaphragm↗
PubMed2000

The new proposed magnetic resonance areas of the cavernous sinus and their relation to the neurosurgical triangles.

MRI appears to be the best contemporary method with which to evaluate cavernous sinus anatomy. Based on anatomic landmarks that are easily detectable in the standard MRI examination, the cavernous sinus is divided into six areas. Each of the newly defined areas corresponds to the previously described neuroanatomic triangles. Evaluation of the newly defined areas in a plane perpendicular to these triangles on a MRI scan permits expansion of these two-dimensional areas into three-dimensional spaces; thus, the neurosurgical approach can be observed and their anatomic and pathologic content examined. Radiologic and surgical evaluation of the cavernous sinus is presented.

Journal Article↗
PubMed2000

The carina as a landmark in central venous catheter placement.

Location of the tip of a central venous catheter (CVC) within the pericardium has been associated with potentially lethal cardiac tamponade. Because the pericardium cannot be seen on chest x-ray (CXR), an alternative radiographic marker is needed for correct placement of CVCs. The anatomy of the region was studied in 34 cadavers. The carina was a mean (SEM) distance of 0.4 (0.1) cm above the pericardial sac as it transverses the superior vena cava (SVC). In no case was the carina located below the pericardial sac. The carina is a reliable, simple anatomical landmark for the correct placement of CVCs. In almost all cases, the carina is radiologically visible even in poor quality, portable CXRs. CVC tips should be located in the SVC above the level of the carina in order to avoid cardiac tamponade.

Aged↗
PubMed1990

Methodology of "in vivo" anatomical study and stereo-electroencephalographic exploration in brain surgery for epilepsy.

Stereotactic implantation of deep SEEG electrodes performed as a prelude to surgery in some patients with drug-resistant focal epilepsy requires previous "in vivo" identification and localization of the cortical and subcortical structures to be explored, visualized "semi-directly" "or directly" by neuroradiological imaging techniques. Stereoscopic stereotactic teleangiography is a safety factor in transcutaneous electrode implantation and biopsies, but it also localizes the cortical sulci in a "semi-direct" manner by identifying vascular segments deeply buried in this sulci, which constitute their lamina vascularis. Although RMI greatly contributes to the study of the pallium, visualizing fragments of sulci and gyri does not necessarily mean that these structures can be identified with certainty, notably on the convexity of the brain. To solve this problem, RMI sections are enlarged by a photographic process, then combined with the images obtained from neuroradiological stereotaxis by means of anatomical landmarks that are common to both types of documents, using the bicommissural reference systems, bicallosal l/nl or vascular segments. This enables the angiographic laminae vascularis, which define the sulci in a "semi-direct" manner, to be used a kind of "Ariadne's clew" to identify cortical structures on RMI sections. In percutaneous stereotactic electrode implantation, the choice of the trajectories results from a compromise between the need to reach the desired anatomical structures, identified and localized within the stereotactic space, and the necessity to avoid the blood vessels displayed by stereoangiography. In some cases, the accuracy of anatomical definition can be verified during the SEEG study and/or by the evoked potential technique. Once the electrodes have been removed, their traces can be identified in a control RMI examination which constitutes a further verification.

Brain↗
PubMed1996

Theoretical situation of brain white matter tracts evaluated by three-dimensional MRI.

An accurate knowledge of cerebral anatomy is important in order to evaluate the precise location of a cerebral lesion. Cortical structures are identified by knowledge of the adjacent gyri and sulci; however, white matter tracts are difficult to differentiate from one another due to the lack of clear anatomic landmarks. Therefore, even if MRI shows obvious white matter abnormalities, in some cases it is difficult accurately to localize the lesion. The purpose of this study is to evaluate the location of the main white matter tracts by using three-dimensional MR imaging. MRI study was performed by 1.5 Tesla (Signa: General Electric). Computer assisted analysis with Voxtool software (General Electric) was used to generate both surface brain and tomographic images. The exact anatomic basis of white matter signal abnormalities is important when analyzing patients with disconnective syndromes or neuropsychological deficits such as conduction aphasia, visuospatial deficit etc. This preliminary attempt at constructing a three-dimensional MRI white matter atlas of the brain may be helpful for evaluating the anatomico-clinical correlations in these patients, and also as teaching materials for the clinical (neurologic, neurosurgical), anatomic and radiographic disciplines.

Adult↗
PubMed2006

Radiological classification of anterior skull base anatomy prior to performing medial orbital wall decompression.

PURPOSE: To study a radiological classification, originally described by Keros in 1965, which provides an objective assessment of anterior skull base anatomy relevant in patients undergoing external medial orbital decompression. MATERIALS AND METHODS: The classification is based on anatomical landmarks measured via coronal CT-scan. The patients are divided into 3 Keros categories based on their olfactory fossa depth; Keros 1 (1-3 mm), Keros 2 (4-7 mm) and Keros 3 (8-16 mm). A cross-sectional group of 32 consecutive patients on the hospital radiology database with coronal CT scans were classified according to the Keros system. RESULTS: All the patients fell into one of the three Keros categories. Anatomical associations of the Keros classification suggest that Keros 1 patients have the least risk of intracranial entry whilst Keros 3 patients carry the greatest risk. CONCLUSION: Keros classification provides an objective assessment of anterior skull base anatomy and can therefore guide the surgeon on the superior extent of medial wall bone removal during orbital decompression. This may help improve the safety profile of the procedure.

Decompression, Surgical↗
PubMed2005

[3D-navigation in nasal sinus surgery].

Mechanical, infra-red and electrofrequency 3D-navigation equipment enables the visualisation of a probe in a patient in the three dimensions ofa CT-scan. Such a system guarantees better orientation in difficult anatomical areas. 3D navigation is particularly suitable for nasal-sinus surgery as the bony structures are reproduced in precise detail on a CT-scan and bone parameters do not change during operation. These technical developments mean that not only the indications for operation but also the surgical approach have greatly altered. In functional nasal-sinus surgery the aim is to open up the sinus by removing all those structures which may hinder drainage. The mucous membrane with its mucociliary transport is spared and goes on to heal. - Prior to operation the patient's anatomical landmarks are tracked and spatially linked to the corresponding points on the CT-scan. The coordinates of these points are registered on a computer. A probe is moved around within the spaces, its coordinates are calculated and their position shown on a CT-scan. The patient's head is fixed in a frame that is able to move with the head. The advantage of the 3D-navigation system is its surgical and anatomical orientation. Disadvantages are its cost and, to a lesser extent, time requirements and the size of the equipment.

Endoscopes↗
PubMed1997

Topographical anatomy of the penile arteries.

OBJECTIVE: To determine the relationship of the penile arteries to anatomical landmarks and thus ease their identification, so avoiding injury during surgery. MATERIALS AND METHODS: The penile arteries in 12 formalin-preserved adult male cadavers were dissected and the distances measured between the cavernosal arteries and both the endopelvic fascia and distal attachment of the crura to the ischial bones. The distance between the origins of both bulbar and cavernosal arteries, their length and the length of the cavernosal bodies and crural attachments were also measured. RESULTS: Several anatomical variations, e.g. accessory pudendal arteries, multiple cavernosal and bulbar arteries, irrigation of cavernosal bodies by contralateral branches, anastomosis of cavernosal arteries with accessory pudendal branches, dorsal artery or bulbar artery as main branches of accessory pudendal arteries, were observed in 13 of the 24 specimens. The mean distances between the anterior attachment of the crura to the ischial rami and the site on the tunica albuginea where the cavernosal arteries penetrated the cavernosal bodies were 1.26 cm on the right and 0.69 cm on the left. The corresponding measurements between the cavernosal arteries and the endopelvic fascia were 5.68 cm (right) and 4.85 cm (left). The mean extracavernosal lengths of the right and left cavernosal arteries were 2.47 and 2.2 cm, respectively. CONCLUSIONS: Multiple anatomical variations of the arterial penile anatomy occur frequently. Surgery at the penile hilum may easily damage the cavernosal arteries, which lie medially to the dorsal nerves and arteries of the penis, have an extracavernosal length of about 2.3 cm and perforate the tunica albuginea about 1 cm distally to the anterior attachment of the crura to the ischial ramus.

Adult↗
PubMed2006

Rotational and translational reproducibility of newly developed Leksell frame-based relocatable fixation system.

PURPOSE: The aim of this study was to evaluate three-dimensional movement of the cranium in a relocatable frame using positions of anatomical landmarks obtained from repeated quality-assurance (QA) computed tomography (CT) studies. MATERIALS AND METHODS: We analyzed 17 series of QA-CT data representing five patients who underwent stereotactic radiotherapy for treatment of acoustic neurinoma. Helical-CT scans with 1-mm collimation were obtained at the time of treatment planning and during the course of treatment. The right and left short processes of the incus and the top of the crista galli were used as the three anatomical reference points. RESULTS: Fluctuations in distance among the reference points were all <1 mm. The translational displacements for these points were <2 mm, with standard deviations (SD) of <2 mm. A plane that included all three reference points was defined as the reference plane. To investigate the direction of cranial rotation for each QA-CT scan, unit normal vectors of the reference plane were obtained. Three-dimensional analyses indicated that cranial rotation was greatest along the X-axis, followed by the Y-axis, with the least rotation along the Z-axis. CONCLUSION: The result suggested that movement of the craniocaudal axis in the sagittal plane was a major factor behind displacement of the cranium.

Adult↗
PubMed2004

A population-based atlas and clinical target volume for the head-and-neck lymph nodes.

PURPOSE: To develop a population-based three-dimensional lymph node target volume of the head and neck. METHODS AND MATERIALS: The T2 weighted axial magnetic resonance imaging (MRI) images of 35 patients with known head and neck cancer were reviewed. An experienced head and neck radiologist marked each lymph node (LN) electronically. The images were distributed to one of 12 axial levels of the head and neck with each level representing a distinct portion of the neck based on external contours and the presence of anatomic structures. The LNs were marked with five different symbols to distinguish the superior/inferior extent of each LN within each level. With the categorization of each image into a different superior/inferior level of the neck, the registration of the images was limited to two dimensions. Nonlinear transformation accounted for inter-patient differences although no local warping was used. The co-registration used recognizable anatomic landmarks (vertebral body, mandible, maxilla, clivus as well as the sternocleidomastoid muscle, external skin contour, spinal cord) to match the patient anatomy. RESULTS: In total, 503 images were co-registered with the baseline images. The majority of the co-registrations were of good quality; 361, 122, and 20 image co-registrations scored as global, limited, and poor co-registrations respectively. One thousand and fifty seven LNs were marked, with 122 LNs marked as submandibular and submental LN. Among the levels A, B, C, D, E, F, G, H, 22, 44, 206, 199, 196, 175, 63, 35 LN were marked respectively. Noteworthy anatomic variation was observed among the different nodal groups that are summarized in the representative baseline images. CONCLUSIONS: Image registration of a series of head and neck images generates a valuable population-based lymph node map that can be used to guide the three-dimensional delineation of the elective lymph node target volume. Significant variation in the lymph node location was seen in all LN groups. The medial border of the internal jugular vein can be used as an important landmark structure in delineating the jugular LN clinical target volume and, for that reason, intravenous contrast is recommended to improve visualization. The location of the submandibular LN appear to be limited to the space anterior and lateral to the submandibular gland and are found mostly along the inferior edge of the mandible. The location of the retropharyngeal LN does vary but their location does not appear to vary with any other recognizable axial structure. The lymph node map provides another collaborating piece of evidence in defining the head and neck LN clinical target volume.

Adolescent↗
PubMed2004

Anatomical resection of left liver segments.

HYPOTHESIS: Anatomical resection of the left liver segments are rarely mentioned in the literature. We describe an anatomical access to the left liver segments' pedicles without hilar dissection. DESIGN: Original surgical technique. PATIENTS AND METHODS: This technique was used in 26 consecutive resections involving left liver segments between July 2001 and December 2003. There were 15 men and 11 women with mean age of 57.1 years. Eleven patients had liver metastasis, 8 had primary liver cancer, 6 had benign lesions, and 1 had gallbladder cancer. The technique consists of small liver incisions according to anatomical landmarks such as the Arantius and round ligaments. In a systematized way, it was possible to reach every glissonian sheath of segments II, III, and IV. RESULTS: Liver resection was feasible using the proposed technique in every patient of this series, and the Pringle maneuver was not required in any patient. Intraoperative blood loss was minimal in all cases, and 23 patients did not require blood transfusion. There was no postoperative death. CONCLUSIONS: This operative procedure allows easy, fast access for anatomical resection of the left liver segments. It is useful for performing controlled hepatectomies without clamping the main hepatic pedicle and may facilitate the recognition of all left liver segment sheaths, with excellent immediate results.

Adult↗
PubMed2004

Applied anatomy of the superior vena cava-the carina as a landmark to guide central venous catheter placement.

BACKGROUND: Cardiac tamponade is a serious complication of central venous catheter (CVC) insertion. Current guidelines strongly advise that the CVC tip should be located in the superior vena cava (SVC) and outside the pericardial sac. This may be difficult to verify as the exact location of the pericardium cannot be seen on a normal chest x-ray. The carina is an alternative radiographic marker for correct CVC placement, suggested on the basis of studies of embalmed cadavers. METHODS: We set out to confirm this radiographic landmark in 39 fresh cadavers (age 58.4 (3.4) (mean and SE) yr) and to compare the results with those from ethanol-formalin-fixed cadavers. RESULTS: We found that the carina was 0.8 (0.05) cm above the pericardial sac as it transverses the SVC. In no case was the carina inferior to the pericardial reflection and our study confirmed the previous findings. All the measured distances were significantly greater in fresh cadavers. CONCLUSIONS: We confirm that the carina is a reliable, simple anatomical landmark that can be identified in vivo for the correct placement of CVCs outside the boundaries of the pericardial sac.

Adult↗
PubMed2006

Virtual reality augmentation in skull base surgery.

OBJECTIVE: Skull base anatomy is complex and subject to individual variation. Understanding the complexity of surgical anatomy is faster and easier with virtual models created from primary imaging data of the patient. This study was designed to investigate the usefulness of virtual reality in image guidance for skull base procedures. DESIGN: Primary volumetric image data from 110 patients was acquired using magnetic resonance, computed tomography (CT), and CT angiography. Pathologies included lesions in the anterior, middle, and posterior skull base. The data were transferred to an infrared-based image-guidance system for creation of a virtual operating field (VOF) with translucent surface modulation and optional "fly-through" video mode. During surgery, the target registration error for anatomical landmarks was assessed and the VOF was compared with the patient's anatomy in the operative field. RESULTS: Complex structures like the course of the sigmoid sinus, the carotid artery, and the outline of the paranasal sinuses were well visualized in the VOF and were recognized by the surgeon instantly. Perception was greatly facilitated as compared with routine mental reconstruction of triaxial images. Accurate assessment of the depth of field and very small objects was not possible in VOF images. CONCLUSION: Supported by sound anatomical knowledge, creation of a virtual operating field for a surgical approach in an individual patient offers a déjà vu experience that can enhance the capabilities of a surgical team in skull base approaches. In addition, application of this technique in image-guided procedures assists in targeting or avoiding hidden anatomical structures.

Journal Article↗
PubMed2004

A double-blind placebo-controlled trial of botulinum toxin B for sialorrhea in Parkinson's disease.

BACKGROUND: Injections of botulinum toxin A are an effective treatment for sialorrhea in Parkinson's disease (PD). Based on the relatively high rates of dry mouth seen with botulinum toxin B, there is reason to suspect that it may also improve sialorrhea. OBJECTIVE: To determine whether botulinum toxin B (Myobloc; Elan Pharmaceuticals, New York, NY) is a safe and effective treatment for sialorrhea in patients with PD. METHODS: Demographics, PD treatments, head posture, the Unified Parkinson's Disease Rating Scale (UPDRS), two questionnaires regarding drooling, Visual Analogue Scale, global impressions, salivary gland imaging, and a dysphagia questionnaire were assessed in 16 PD subjects with problematic sialorrhea. Patients were then randomized to receive either botulinum toxin B (1,000 units into each parotid gland and 250 units into each submandibular gland) or a pH-matched placebo, using only anatomic landmarks. Patients returned 1 month later to undergo an identical assessment. RESULTS: Compared with placebo, those randomized to drug reported improvement on the Visual Analogue Scale (p < 0.001), global impressions of change (p < 0.005), Drooling Rating Scale (p < 0.05), and Drooling Severity and Frequency Scale (p < 0.001). There was no change in UPDRS, head posture, or Dysphagia Scale. Adverse events were mild and included dry mouth (three patients), worsened gait (two), diarrhea (one), and neck pain (one) in the botulinum toxin B group. CONCLUSION: Anatomically guided injections of botulinum toxin B into the parotid and submandibular glands appear to effectively improve sialorrhea without compromising dysphagia in patients with PD.

Aged↗