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At least 487 records · Page 27Linked to original sources
PubMed2005

Catheter location, tracking, cardiac chamber geometry creation, and ablation using cutaneous patches.

OBJECTIVE: The ability to construct a three-dimensional (3-D) surface model of the endocardium and track the location of catheters within a cardiac chamber, using only cutaneous patches, would be a useful advancement in treating arrhythmias. We tested the feasibility of such a system, Ensite NavX (Endocardial Solutions, Inc., St. Paul, MN, USA), in patients undergoing catheter ablation for SVTs. METHODS: Sixteen patients with 20 arrhythmias undergoing ablation were selected. Skin electrode patches were placed on the chest to create a 3-D coordinate system. A low-amplitude, 5.7 kHz signal emitted from the patches was received by conventional catheters positioned in the heart. Catheter location was determined by measuring the field strength received by the catheters. Location points were successively acquired while catheters were moved throughout the chamber. This information was collected and processed by a workstation to create a detailed 3-D model of the endocardial surface. Anatomic landmarks were labeled on the model as the mapping catheter was navigated. 3-D cardiac chamber geometry reconstruction, landmark labeling, and real time catheter tracking were performed successfully in all patients. Up to six catheters, with a total of up to 26 intracardiac electrodes, were tracked simultaneously. RESULTS: Constructed geometries, including major vessels and valves, correlated closely with traditional anatomic models as well as intracardiac recordings and fluoroscopic images. CONCLUSIONS: Real-time catheter tracking and 3-D cardiac chamber model construction is feasible using cutaneous patches and conventional catheters. This approach may be useful in the treatment of patients with cardiac arrhythmias where ablation therapy is primarily anatomically based.

Adult↗
PubMed1997

Phosphor-stimulated computed cephalometry: reliability of landmark identification.

The aim of this randomized, controlled, prospective study was to determine the reliability of computed lateral cephalometry (Fuji Medical Systems, Tokyo, Japan) in terms of landmark identification compared to conventional lateral cephalometry (CAWO, Schrobenhausen, Germany). To assess the reliability of landmark identification on lateral cephalographs, 20 computed images, taken at 30 per cent reduced radiation (70 kV, 15 mA, 0.35 s) were compared to 20 conventional images (70 kV, 15 mA, 0.5 s). The 40 lateral cephalographs were taken from 20 orthodontic patients at immediate post-treatment and 1 year after retention. The order and type of imaging was randomized. Five orthodontists identified eight skeletal, four dental and five soft tissue landmarks on each of the 40 films. The error of identification was analysed in the XY Cartesian co-ordinate following digitization. Skeletal landmarks exhibited characteristic dispersion with respect to the Cartesian co-ordinates. Root apices were more variable than crown tips. Soft tissue landmarks were more consistent in the X co-ordinate. Two-way ANOVA shows that there is no significant difference between the two imaging systems in both co-ordinates (P > 0.05). Moreover, the differences are generally small (< 0.5 mm), and are unlikely to be of clinical significance. Most of the variables attained statistical power of at least 0.8 in the X-co-ordinate while only the dental landmarks achieved statistical power of at least 0.78 in the Y-co-ordinate. Based on the results of the study: (1) computed lateral cephalographs can be taken at 30 per cent radiation reduction, compared to conventional lateral cephalograph; (2) each anatomical landmark exhibits its characteristic dispersion of error in both the Cartesian co-ordinates; (3) there is no trend between the two imaging systems, with equivocal result, and none of the landmarks attained statistical significance when both raters and imaging systems are considered as factorial variables; (4) the random error of raters in landmark identification after replicate tracing was highlighted and needs to be taken into consideration in all studies involving landmark identification.

Adolescent↗
PubMed2002

[Training for adult subclavian venous catheterization: use of real-time echography].

OBJECTIVE: To assess the training in adult subclavian venous catheterization of an inexperienced operator, with two different procedures: ultrasound guidance vs anatomic landmark technique. STUDY DESIGN: Prospective, comparative study. PATIENTS AND METHODS: After informed consent, 50 adults were divided in two groups, with an original method of inclusion, designed to assess the training of the operator, which alternated ultrasound guidance (n = 25) and Aubaniac's landmark technique (n = 25). RESULTS: All the catheterizations have been completed. The success rate at first attempt was higher in ultrasound group than in landmark group, without reaching significance (76 vs 56%). Two arterial punctures were reported in landmark group. With ultrasound guidance, there were 21 puncture sites at the external third and 4 at the medial third of the clavicle. Average access time (skin to vein) was 15 +/- 8 seconds in ultrasound group and 63 +/- 78 seconds in landmark group (p < 0.01), with a significant relation between access time and patient rank in landmark group (r2 = 0.42, p < 0.01). CONCLUSION: Ultrasound guidance makes the training in adult subclavian venous catheterization easier, and allows inexperimented operator to be rapidly efficient. The use of ultrasound would decrease the incidence of complications by a real time visualization of anatomical structures, and by a more external approach of the vein than in the Aubaniac's technique.

Aged↗
PubMed2003

MRI volumetric analysis in rasmussen encephalitis: a longitudinal study.

PURPOSE: Rasmussen encephalitis is a progressive inflammatory process with difficult-to-control focal or lateralized seizure activity, leading to hemispheric dysfunction and atrophy in advanced stages. Anatomic changes of atrophy may be subtle in earlier phases of the disease, and progressive changes on serial scans may be difficult to detect. We report a case of early-stage Rasmussen encephalitis with a relatively stable clinical course in whom we performed magnetic resonance imaging (MRI)-based volumetric analysis over an interval of 1 year, to assess for volumetric changes. METHODS: Volumetric analysis was performed on two successive MRI scans obtained at age 5 and 6 years, by using the CARDVIEWS program (J Cogn Neurosci, 1996). The images were segmented into gray- and white-matter structures according to signal intensity of their borders semiautomatically, with manual corrections. The cerebral cortex was further subdivided into smaller parcellation units according to anatomic landmarks identifiable on MRI. RESULTS: Stable left cerebral hemispheric atrophy and progressive atrophy in the left precentral gyrus, left inferior frontal gyrus, and left cerebellar atrophy were detected over the 1-year interval. CONCLUSIONS: Volumetric analysis enables early detection and quantification of anatomic changes, identification of focal involvement, and assists in determining the severity of disease and timing for surgical interventions such as hemispherectomy.

Atrophy↗
PubMed2001

[MRI in the preoperative diagnosis of chronic sinusitis: comparison with CT].

PURPOSE: To determine the value of MRI in the preoperative evaluation of chronic paranasal sinusitis and to compare the results with CT and intraoperative findings. METHOD/MATERIALS: 42 patients with clinical signs of chronic paranasal sinusitis underwent MRI after CT evaluation on one day, with subsequent functional endoscopic sinus surgery on the next day. Coronary CT was obtained with 5-mm slices and table-feed in the prone position, while MRI was performed in the supine position with coronary T2-TSE + pd and coronary and transverse HASTE, each with 5-mm slice thickness. Aquisition time in MRI was less than 8 minutes. Two radiologists reviewed the CT and MRI scans for signs of sinusitis and detection of anatomical landmarks. The results were correlated with the intraoperative findings. RESULTS: MRI offered no artifacts of dental work and showed more often high quality pictures than CT. CT and MRI demonstrated a good correlation in the detection of mucosal pathologies (kappa = 0.46-0.87) and anatomic variants (kappa = 0.55-0.86). All important anatomical structures could be evaluated sufficiently with MRI for preoperative management. Both diagnostic tools showed an unsatisfactory correlation with intraoperative findings in the ethmoidal complex and maxillary sinus (tau = -0.08-0.3). CONCLUSIONS: MRI is a fast and reliable alternative to preoperative CT in examining paranasal sinuses and offers a good visualization of mucosal changes. CT and MRI both give an unreliable representation of the ethmoidal complex.

Artifacts↗
PubMed2002

Electronic and film portal images: a comparison of landmark visibility and review accuracy.

PURPOSE: To quantitatively compare a scanning liquid ion chamber electronic portal imaging device (SLIC-EPID) and an amorphous silicon flat panel (aSi) EPID with portal film in clinical applications using measures of landmark visibility and treatment review accuracy. METHODS AND MATERIALS: Six radiation oncologists viewed 39 electronic portal images (EPIs) from the SLIC-EPID, 36 EPIs from the aSi-EPID, and portal films of each of these treatment fields. The physicians rated the clarity of anatomic landmarks in the portal images, and the scores were compared between EPID and film. Nine hundred portal image reviews were performed. EPID and film portal images were acquired with known setup errors in either phantom or cadaver treatments. Physicians identified the errors visually in portal films and with computerized analysis for EPID. RESULTS: There were no statistically significant (p < 0.05) differences between film and SLIC-EPID in ratings of landmark clarity. Eleven of 12 landmarks were more visible in aSi-EPID than in film. Translational setup errors were identified with an average accuracy of 2.5 mm in film, compared to 1.5 mm with SLIC-EPID and 1.3 mm with aSi-EPID. CONCLUSIONS: Both EPIDs are clinically viable replacements for film, but aSi-EPID represents a significant advancement in image quality over film.

Movement↗
PubMed1991

Relationship of hippocampus and amygdala to coronal MRI landmarks.

Magnetic resonance imaging is playing an increasingly important role in the evaluation of the hippocampus, particularly in epilepsy, schizophrenia, and Alzheimer's dementia. Because of the complex configuration of the hippocampus, it is difficult to compare from patient to patient. We developed a system to allow comparison of the hippocampus on coronal images. We performed 34 magnetic resonance studies on 29 normal subjects. Ten anatomic landmarks were identified. These landmarks have a consistent 5-mm periodicity regardless of usual head flexion. In the second phase of our investigation, we showed that the amygdala, hippocampal head, hippocampal body, and hippocampal tail have a consistent relationship to the coronal magnetic resonance imaging landmarks.

Adolescent↗
PubMed1989

Muscle fibre direction of longissimus, iliocostalis and multifidus: landmark-derived reference lines.

Considerable inter-individual variations in the fibre direction angles of the iliocostalis lumborum, longissimus and multifidus were observed, thus bringing the applicability of a two dimensional fixed angle grid system for fibre direction determination into question. However, the angulation of the fibres of the multifidus and iliocostalis lumborum were found to be easily identifiable by the use of three surface anatomical landmarks: the caudal tip of the superior iliac spine, the lateral border of the iliocostalis at the twelfth rib and the L1-L2 interspinous space. No reliable index was found for the longissimus. Suggested electrode placement sites for the electromyographic study of the iliocostalis lumborum and the multifidus are at the levels of the L2-L3 and the L4-L5 interspinous spaces respectively.

Biometry↗
PubMed2004

Laparoscopic adrenalectomy for Conn's syndrome complicated by ipsilateral congenital pelvic kidney.

A patient presented with hypertension, hypokalemia, and a 1.2-cm left adrenal tumor. Conn's syndrome was diagnosed, for which laparoscopic adrenalectomy is now the therapy of choice. This case was complicated by an ipsilateral ectopic pelvic kidney. A laparoscopic left adrenalectomy was performed via a lateral transabdominal approach. Without the usual anatomic landmark of the ipsilateral kidney, the left adrenal gland was difficult to identify, so intraoperative ultrasound was used to locate the lesion. Postoperatively, the patient's blood pressure and potassium normalized. This is the first documented report of a laparoscopic adrenalectomy performed for adrenal adenoma with the anatomic disruption of an ipsilateral pelvic kidney.

Adrenalectomy↗
PubMed2005

Anterior sciatic nerve block--new landmarks and clinical experience.

BACKGROUND: Anterior sciatic nerve blocks can be complicated by several problems. Pain can be caused by bony contacts and, in obese patients, identification of the landmarks is frequently difficult. METHODS: In a first step, 100 normal anterior-posterior pelvic X-rays were analyzed. The landmarks of the classical anterior approach were drawn on these X-rays and assessed for their sufficiency. Then, in a prospective case study, 200 consecutive patients undergoing total knee replacement were investigated. These patients received femoral and sciatic nerve catheters for postoperative pain management. Using modified anatomical landmarks, sciatic nerve catheters were inserted 5 cm distal from the insertion site of the femoral nerve block perpendicularly in the midline of the lower extremity. This midline connected the insertion site of the femoral nerve catheter to the midpoint between the medial and lateral epicondyle. Correct catheter positioning was verified by magnetic resonance imaging (MRI) in six patients. RESULTS: Evaluation of pelvic X-rays showed that puncture following the classical landmarks pointed in 51% at the lesser trochanter, in 5% medial to the lesser trochanter and in 42% directly at the femur. In the latter patients, location of the sciatic nerve would have been difficult or even impossible. Using our modified anterior approach, the sciatic nerve could be blocked in 196 patients (98%). In nine patients (4.5%) blockade of the posterior femoral cutaneous nerve failed. Vascular puncture happened in 10 (5%) and bony contact in 35 patients (17.5%). Median puncturing depth was 9.5 (7.5-14) cm. Correct sciatic nerve catheter positioning was verified in all patients who underwent MRI. CONCLUSION: Our landmarks for locating the sciatic nerve help to avoid bony contacts and thereby reduce pain during puncture. Our method reliably enabled catheter placement.

Aged↗
PubMed2005

Content-based image database system for epilepsy.

We have designed and implemented a human brain multi-modality database system with content-based image management, navigation and retrieval support for epilepsy. The system consists of several modules including a database backbone, brain structure identification and localization, segmentation, registration, visual feature extraction, clustering/classification and query modules. Our newly developed anatomical landmark localization and brain structure identification method facilitates navigation through an image data and extracts useful information for segmentation, registration and query modules. The database stores T1-, T2-weighted and FLAIR MRI and ictal/interictal SPECT modalities with associated clinical data. We confine the visual feature extractors within anatomical structures to support semantically rich content-based procedures. The proposed system serves as a research tool to evaluate a vast number of hypotheses regarding the condition such as resection of the hippocampus with a relatively small volume and high average signal intensity on FLAIR. Once the database is populated, using data mining tools, partially invisible correlations between different modalities of data, modeled in database schema, can be discovered. The design and implementation aspects of the proposed system are the main focus of this paper.

Brain↗
PubMed1980

A survey of panoramic radiographs for evaluation of normal and pathologic findings.

Six thousand seven hundred eighty panoramic radiographs were screened to monitor the incidence of normal and pathologic findings. Three different types of panoramic radiograph were used in this study: Panorex, Orthopantomograph, and Panelipse. Visualization of four different anatomic landmarks was used for a statistical comparison of the diagnostic value of the three films: the temporomandibular joint compartments, the external oblique ridge, the mental foramen, and the mandibular canal. The orthopantomograph was judged to be slightly more reliable in producing radiographs for the visualization of the selected anatomic structures. The most common form of pathosis detected was impacted teeth, seen in 22.3 percent followed by retained roots, which appeared in 12.6 percent of the films. Comparing these survey data with three other major studies suggests that confining the previous radiographic examinations to certain selected groups of people may have distorted the incidence of some pathologic conditions in the population. The panoramic radiograph is still considered a supplement to, not a substitute for, the intraoral radiograph.

Humans↗
PubMed2005

Prostate position relative to pelvic bony anatomy based on intraprostatic gold markers and electronic portal imaging.

PURPOSE: To describe the relative positions and motions of the prostate, pelvic bony anatomy, and intraprostatic gold fiducial markers during daily electronic portal localization of the prostate. METHODS AND MATERIALS: Twenty prostate cancer patients were treated supine with definitive external radiotherapy according to an on-line target localization protocol using three or four intraprostatic gold fiducial markers and an electronic portal imaging device. Daily pretherapy and through-treatment electronic portal images (EPIs) were obtained for each of four treatment fields. The patients' pelvic bony anatomy, intraprostatic gold markers, and a best visual match to the target (i.e., prostate) were identified on simulation digitally reconstructed radiographs and during daily treatment setup and delivery. These data provided quantitative inter- and intrafractional analysis of prostate motion, its position relative to the bony anatomy, and the individual intraprostatic fiducial markers. Treatment planning margins, with and without on-line localization, were subsequently compared. RESULTS: A total of 22,266 data points were obtained from daily pretherapy and through-treatment EPIs. The pretherapy three-dimensional (3D) average displacement of the fiducial markers, as a surrogate for the prostate, was 5.6 mm, which improved to 2.8 mm after use of the localization protocol. The bony anatomy 3D average displacement was 4.4 mm both before and after localization to the prostate (p = 0.46). Along the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) axes, the average prostate displacement improved from 2.5, 3.7, and 1.9 mm, respectively, before localization to 1.4, 1.6, and 1.1 mm after (all p < 0.001). The pretherapy to through-treatment position of the bony landmarks worsened from 1.7 to 2.5 mm (p < 0.001) in the SI axis, remained statistically unchanged at 2.8 mm (p = 0.39) in the AP axis, and improved from 2.0 to 1.2 mm in the RL axis (p < 0.001). There was no significant intrafractional displacement of prostate position or bony anatomic landmarks. An intermarker distance was identified for all fiducial markers, and 96 were followed daily. Seventy-nine percent had a standard deviation of <1 mm, and 96% were <1.5 mm. Margins were 5.1, 7.3, and 5.0 mm in the SI, AP, and RL axes, respectively, before localization and 2.7, 2.9, and 2.8 mm after localization. CONCLUSIONS: Significant interfractional motion exists for patients' prostate and pelvic bony anatomy. However, these move independently, so the pelvic bony anatomy should not be used as a surrogate for prostate motion. Fiducial markers are stable within the prostate and allow significant margin reduction when used for on-line localization of the prostate.

Gold↗
PubMed2006

A new toolbox for combining magnetoencephalographic source analysis and cytoarchitectonic probabilistic data for anatomical classification of dynamic brain activity.

Size and location of activated cortical areas are often identified in relation to their surrounding macro-anatomical landmarks such as gyri and sulci. The sulcal pattern, however, is highly variable. In addition, many cortical areas are not linked to well defined landmarks, which in turn do not have a fixed relationship to functional and cytoarchitectonic boundaries. Therefore, it is difficult to unambiguously attribute localized neuronal activity to the corresponding cortical areas in the living human brain. Here we present new methods that are implemented in a toolbox for the objective anatomical identification of neuromagnetic activity with respect to cortical areas. The toolbox enables the platform independent integration of many types of source analysis obtained from magnetoencephalography (MEG) together with probabilistic cytoarchitectonic maps obtained in postmortem brains. The probability maps provide information about the relative frequency of a given cortical area being located at a given position in the brain. In the new software, the neuromagnetic data are analyzed with respect to cytoarchitectonic maps that have been transformed to the individual subject brain space. A number of measures define the degree of overlap between and distance from the activated areas and the corresponding cytoarchitectonic maps. The implemented algorithms enable the investigator to quantify how much of the reconstructed current density can be attributed to distinct cortical areas. Dynamic correspondence patterns between the millisecond-resolved MEG data and the static cytoarchitectonic maps are obtained. We show examples for auditory and visual activation patterns. However, size and location of the postmortem brain areas as well as the inverse method applied to the neuromagnetic data bias the anatomical classification. Therefore, the adaptation to the respective application and a combination of the objective quantities are discussed.

Acoustic Stimulation↗
PubMed2000

An anteromedial internal jugular vein successfully cannulated using the assistance of ultrasonography.

The internal jugular vein usually is found either lateral or anterolateral to the carotid artery when it is cannulated for central vein access using external anatomical landmarks. We report a case in which the carotid artery was inadvertently punctured, but the right internal jugular vein could not be found. We used ultrasonic guidance to determine that the right internal jugular vein was anteromedial to the carotid artery. A figure showing the ultrasound of this rare anatomical variation is provided. The advantages and utility of ultrasound when used for the placement of internal jugular central vein catheters are reviewed.

Aged↗
PubMed1999

Transsphenoidal reoperations for removal of pituitary adenomas: rhinological management and timing of reoperation.

Transsphenoidal reoperation of pituitary adenomas remain a difficult surgical procedure even with skilful microsurgical techniques. This paper retrospectively analysed how to overcome such difficult factors as absent normal surgical landmarks and an adhesive field. For residual or recurrent adenomas, transsphenoidal reoperations were carried out 14 times in 12 patients. Reasons for reoperations were intentionally multistaged operations in 10 cases, regrowth in three and apoplexy in one. In the first operation, we tried to preserve or restore as many anatomic landmarks as possible. Overly aggressive procedures causing cerebrospinal fluid leakage were avoided. In the three second reoperations within 3 months, a transnasal approach was used. In the other eight situations, between 4 and 119 months, transnasal approach in five, and transseptal approach in three, were used retrospectively. In two patients with fibrous adenomas, reoperations were carried out 4 and 12 months after the first. Magnetic resonance imaging (MRI) evaluation is essential to confirm the tumour descent toward or into pituitary fossa. Timing of the reoperation needs to be individualized depending on MRI findings. Trauma to the nasal mucosa and a narrower operative field became more frequent in reoperations 4 months or later. To obtain a surgical field wide enough to manipulate an ultrasonic aspirator for fibrous adenomas, removal of bony structures at the nasal cavity on the surgical corridor is useful. These rhinological preparations in the first and subsequent operations along with a selection of timing of reoperation are important to gain easier access for tumour removal and in avoidance of surgical complications. Copyright 1999 Harcourt Publishers Ltd.

Journal Article↗
PubMed2002

The arrangement of muscle fibres in the region of the subthebesian fossa in the aspect of atrial flutter.

The typical atrial flutter is the most common supraventricular tachycardia with reentrant circuit. This tachyarrythmia is based on macroreentry wave going around established anatomic landmarks. The reentry in the inferior right atrial wall passes through narrow isthmus, which is the goal for ablative therapy. The isthmus area is bordered anteriorly by the tricuspid valve and posteriorly by the inferior vena cava, coronary sinus, and eustachian ridge. Near to this area we can find anatomical structure, which can be very important during arising, perpetuation and curing of atrial flutter. The concavity, so-called subthebesian fossa, is on the way of typical atrial flutters' reentrant circuit. Regarding the facts mentioned above we decided to examine the morphology and the arrangement of the muscle fibres in this fossa. Research was conducted on material consisting of 70 human hearts of both sexes from the age of 34 to 72 years. 50 hearts came from patients whose death was not cardiologic in origin. 20 hearts came from humans in whose common atrial flutter was confirmed. We observed the arrangement of muscle fibres in the area of subthebesian fossa. Besides we measured the size and deepness of the subthebesian fossa in both groups of hearts. We found that regular arrangement of muscle fibres within subthebesian fossa was present in 23 healthy human hearts (46%) and 7 cases (35%) of hearts with atrial flutter. The irregular arrangement of muscle fibres was observed in 27 hearts (54%) of control group and 13 hearts (65%) with dysrrhythmia. The thickness of the right atrial wall within the subthebesian fossa was very thin in 8 normal hearts (16%) and in 5 dysrrhythmic hearts (25%). The sizes of examined structure were variable in both groups of hearts, and are presented in the table. It seems that the subthebesian concavity can be the substrate for reentrant circuit during atrial flutter, and there could be such special arrangement of muscle fibres, which allows for microreentrant circuit to arise in this area.

Adult↗
PubMedDate not supplied

Combined PET-CT in the head and neck: part 1. Physiologic, altered physiologic, and artifactual FDG uptake.

Positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG) has been effective for the diagnosis, staging, and restaging of malignancies of the head and neck region. However, lack of anatomic landmarks, variable physiologic uptake, and asymmetric FDG distribution in several altered physiologic states can confound image interpretation. In addition, many benign causes and several artifacts can simulate physiologic or pathologic FDG uptake in the head and neck. Combined PET-computed tomography (CT) is a unique imaging modality that permits anatomic and functional imaging on a single scanner with nearly perfect coregistration. Combined PET-CT provides information that cannot be obtained with PET or CT alone. In particular, PET-CT facilitates the interpretation of FDG uptake in the head and neck, an area that is characterized by dense and complex anatomic structures. An atlas of FDG uptake in this anatomic region was compiled on the basis of combined PET-CT findings in 11,000 patients. In general, patterns of FDG uptake were variable and often reflected patient activity during or immediately preceding the uptake phase. With the growing interest in PET-CT, interpreting radiologists and nuclear medicine physicians must be familiar with the patterns of FDG uptake in the head and neck to avoid misinterpretation or mis-diagnosis.

Artifacts↗