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At least 685 records · Page 38Linked to original sources
PubMed2004

Protocol for volumetric segmentation of medial temporal structures using high-resolution 3-D magnetic resonance imaging.

Quantitative analysis of brain structures in normal subjects and in different neurological conditions can be carried out in vivo through magnetic resonance imaging (MRI) volumetric studies. The use of high-resolution MRI combined with image post-processing that allows simultaneous multiplanar view may facilitate volumetric segmentation of temporal lobe structures. We define a protocol for volumetric studies of medial temporal lobe structures using high-resolution MR images and we studied 30 healthy subjects (19 women; mean age, 33 years; age range, 21-55 years). Images underwent field non-homogeneity correction and linear stereotaxic transformation into a standard space. Structures of interest comprised temporopolar, entorhinal, perirhinal, parahippocampal cortices, hippocampus, and the amygdala. Segmentation was carried out with multiplanar assessment. There was no statistically significant left/right-sided asymmetry concerning any structure analyzed. Neither gender nor age influenced the volumes obtained. The coefficient of repeatability showed no significant difference of intra- and interobserver measurements. Imaging post-processing and simultaneous multiplanar view of high-resolution MRI facilitates volumetric assessment of the medial portion of the temporal lobe with strict adherence to anatomic landmarks. This protocol shows no significant inter- and intraobserver variations and thus is reliable for longitudinal studies.

Adult↗
PubMedDate not supplied

A bloodless technique for tongue surgery.

The Cavitron Ultrasonic Surgical Aspirator (CUSA System) has been used at our institution in the resection of carcinoma of the tongue in 10 patients. This device is an ultrasonically powered aspirator that selectively fragments and aspirates tissue within a 1- to 2-mm radius of its tip. The technique used in our unit in tongue surgery was to incise the touch mucosal capsule of the tongue with electrocautery, and then to divide muscle and skeletonize blood vessels using the CUSA System. Smaller vessels, up to 2 mm in size, were cauterized directly by the friction created at the tip of the instrument. In this way, excellent control was available at all times and blood loss was consequently minimal. As our experience in the use of the CUSA System increased, blood loss was virtually eliminated, anatomic landmarks were more easily defined, and at no stage did any tongue necrosis occur in any of the patients of the series.

Animals↗
PubMed2002

Bone morphing: 3D morphological data for total knee arthroplasty.

OBJECTIVE: The clinical outcome of a total knee arthroplasty (TKA) is mainly determined by the accuracy of the surgical procedure itself. To improve the final result, one must take into account (a) the alignment of the prosthesis with respect to the mechanical axis, and (b) the balance of the soft tissues. Therefore, morphologic data (such as the shape of the epiphysis) and geometric data are essential. We present a new method for performing TKA based on morphologic and geometric data without preoperative images. MATERIALS AND METHODS: The global method is based on the digitization of points with an optical 3D localizer. For the morphologic acquisitions, we use a method based on the registration of sparse point data with a 3D statistical deformable model. To build the mechanical axis, we use a kinematics method for the hip center and digitization of anatomical landmarks for the ankle centers. The knee center is not determined by digitization or kinematics of the knee, as this would not be accurate. The surgical planning relies totally on the soft-tissue balance, which is the key issue for a good kinematics result. RESULTS: We have used this system for 6 months in a randomized clinical trial involving 35 patients to date. For the first 11 patients that could be measured in the navigation group, the postoperative frontal alignment was within the range of 180 +/- 3 degrees. Fluoroscopic assessment of the soft-tissue balancing will be performed at the conclusion of an extended 2-year study to evaluate the results from a functional point of view. CONCLUSION: Bone Morphing is an accurate, fast, and user-friendly method that can provide morphologic as well as geometric data. We have introduced the important notion of soft-tissue balancing into the intraoperative planning step to optimize the kinematics as well as the anatomy. Therefore, this method should be considered as an alternative to the CT-based method.

Algorithms↗
PubMed1991

Three-dimensional reconstruction and cross-sectional anatomy of the thigh musculature of the developing chick embryo (Gallus gallus).

The technique of graphical reconstruction by orthogonal projection of serial sections is used to generate three-dimensional models of embryonic chick thigh musculature at Hamburger-Hamilton ('51) stages 36 (day 10) and 39 (day 13). Unique and conserved anatomical landmarks are described, which can be used to specify position along the proximo-distal axis of the thigh from cross-sectional appearance. These landmarks provide an important reference for both current and future experimentation in which a precise developmental site must be systematically and repeatedly sampled.

Animals↗
PubMed2001

Automated registration of dynamic MR images for the quantification of myocardial perfusion.

Cardiac dynamic magnetic resonance imaging (MRI) after contrast media injection suffers from motion induced by free breathing during acquisition. This work presents an automated approach for motion correction of the heart. The registration is based on the multipass/multiresolution iterative minimizing of intrinsic differences between each image and a reference image coupled to a two-dimensional/3 parameters rigid body correction. The efficiency of this correction method was evaluated with anatomical landmarks, various cost functions, and for a compartment model fit of the data with 2 parameters: K1, the blood to myocardium transfer coefficient; and Vd, the distribution volume of the contrast media. The variability of K1 and Vd, derived from the fit of the registered images (using the manual correction as a gold standard), was significantly reduced by comparison with the variability obtained from the uncorrected images (P < 0.04). This motion correction method also clearly improves the analysis of dynamic cardiac MRI after contrast media injection in comparison to manual correction.

Contrast Media↗
PubMedDate not supplied

Comparison of T2-weighted spin-echo and fast spin-echo techniques in the evaluation of myelination.

To evaluate T2-weighed fast spin-echo (FSE) and conventional spin-echo (CSE) magnetic resonance (MR) techniques in the assessment of brain myelination, 100 consecutive pediatric patients were imaged prospectively with both CSE and FSE sequences. All patients underwent a routine MR examination that included T2-weighted CSE imaging (imaging time, 10 minutes 21 seconds) and T2-weighted FSE imaging (imaging time, 2 minutes 5 seconds). The two techniques were compared for estimating the degree of myelination (using normal anatomic landmarks) by blind review. With T2-weighted CSE images as the "gold standard" for estimation of normal myelination, FSE images were evaluated to determine if they showed the degree of myelination similarly to CSE images. There was a strong correlation (P < .01) between CSE and FSE images in the estimation of myelination over a wide range of patient ages.

Adolescent↗
PubMedDate not supplied

Novel application of breath-hold turbo spin-echo T2 MRI for detection of acute myocardial infarction.

To assess the clinical utility of the breath-hold turbo spin-echo T2-weighted MRI in patients with acute myocardial infarction, the results of MRI were compared with those of electrocardiography, coronary angiography, and thallium-201 single photon emission tomography (SPECT) in 23 patients and 5 healthy volunteers. To compare MRI and thallium-SPECT, the left ventricle was divided into five segments, and the presence of myocardial infarction was determined in each segment. MRI demonstrated an abnormally bright signal in 49 of 140 segments (five segments each from 23 patients and 5 volunteers); thallium-SPECT showed a fixed perfusion defect in 52 segments, for an 85% diagnostic concordance rate. The size of the myocardial infarction measured on MRI corresponded well to that measured on thallium-SPECT (r = .70, P < .01). Breath-hold turbo spin-echo T2 MRI can be used for detection of acute myocardial infarction in conjunction with thallium-SPECT, especially when accurate localization of lesion, increased spatial resolution, and anatomic landmarks are needed.

Coronary Angiography↗
PubMedDate not supplied

Evaluation of 3D image registration as applied to MR-guided thermal treatment of liver cancer.

There are many potential applications of three-dimensional (3D) image registration in MR-guided radiofrequency (RF) thermal ablation of tumors. For example, after registration of image volumes obtained before and after thermal ablation, a variety of quantitative and visual assessments of therapy were performed. For liver tumors, the accuracy of rigid body, manual registration on 19 pairs of image volumes was evaluated, almost all of which were obtained during thermal treatment sessions. Registration error was estimated as a distance between anatomical landmarks, including both internal vascular structures as well as the surface of the liver. Over all image pairs and throughout a large portion of the liver, the registration error was 3.1 mm (mean + 1 SD). From the bottom to the top of the liver, error increased on the order of 13%, probably because of liver motion and deformation resulting from respiration. Although probably insufficient for blind guidance of therapy, registration accuracy was undoubtedly sufficient for interesting applications in the planning, assessment, and optimization of interventional MR-guided thermal treatment of liver tumors.

Catheter Ablation↗
PubMed1985

Transvenous ablation of the atrioventricular conduction system by laser irradiation under endoscopic control.

We report ten successful experiments of transvenous destruction of the His bundle by laser radiation. An endoscope coupled with a special laser catheter was introduced through the jugular vein into the right atrium of dogs. The tip of the laser catheter was positioned in front of A-V conduction system under visual control using anatomic landmarks. Injection of saline solution coaxial with the laser power-transmitting fiber was performed before and during laser coagulation. Twenty watts constant wave Nd-YAG laser operating at 1.06 micron was enough to produce complete A-V block in approximately 15 sec. The safety of the proposed technique is especially discussed.

Animals↗
PubMed2006

Optimal recording electrode placement in the lumbrical-interossei comparison study.

The lumbrical-interossei comparison study is commonly employed in the electrodiagnosis of carpal tunnel syndrome. Placement of the recording electrodes relies on anatomic landmarks as the muscles being recorded cannot be seen or palpated. To determine the optimal active electrode location, 15 controls and 5 patients were studied using a grid of 12 electrodes placed over the lateral palm. Amplitudes, rise-times, and latencies of the responses at each location were measured. The lowest control latency difference was located in the lateral mid-proximal palm (mean 0 ms, upper range of 0.5 ms). This location also had the highest lumbrical amplitude and rise-time. More distal in the palm, the mean latency difference increased to 0.5 ms with an upper range of 0.9 ms. When performing the lumbrical-interossei comparison study, it is essential to place the active recording electrode in the optimal location. Failure to do so will result in an increased number of false-positive studies.

Adult↗
PubMed2002

Detection and correction of endotracheal-tube position in premature neonates.

Due to the short airways in premature children, an accurate position of the endotracheal tube (ETT) is crucial for adequate mechanical ventilation. Verification of ETT-position is done in chest radiographs. However, ETT-position varies substantially with head movement. When the head is flexed, the tube might appear too deeply inserted, and inadvertent extubation may occur in cases of retraction of ETT after radiography. Extension of the cervical spine will suggest an inappropriately high ETT-position, so that intended corrections can lead to main-stem intubation. Radiographic visible skeletal structures could serve as reference points to allow the detection of head declination and imperfect positioning of ETT. Ratios of anatomical landmarks were used to estimate head position. In this study, 111 radiographs of 24 preterm neonates with a gestational age of 24-29 weeks and weights of 500-1,000 g were analyzed. A mathematical algorithm for the detection and correction of ETT-positions, based on common chest radiographs, was developed. In 108 cases (97.3%), ETT-distance from the midtracheal level was less than 2 mm after use of the proposed correction.Thus, the suggested correction equation for head position enables verification of the actual ETT-position without requiring a defined placement of the head during radiography. Moreover, it can be helpful for estimating the depth of ETT-insertion in conditions when radiography is not available.

Algorithms↗
PubMed2003

Fetal sonographic diagnosis of aortic arch anomalies.

Aortic arch anomalies refer to congenital abnormalities of the position or branching pattern, or both of the aortic arch. Although aortic arch anomalies are not uncommon, reports on their prenatal diagnosis are scarce. Insight into the hypothetical arch model is crucial to understanding anomalies of the aortic arch in the fetus. Recognition of the trachea, three major vessels, ductus arteriosus and descending aorta in the axial views of the upper mediastinum is necessary for a complete fetal cardiac assessment. Clues to aortic arch anomalies include abnormal position of the descending aorta, absence of the normal 'V'-shaped confluence of the ductal and aortic arches, a gap between the ascending aorta and main pulmonary artery in the three-vessel view, and an abnormal vessel behind the trachea with or without a vascular loop or ring around the trachea. Meticulous attention to anatomic landmarks will lead to successful prenatal diagnosis of important vascular rings making early postnatal management possible.

Aorta, Thoracic↗
PubMed2001

Synthesis and mobilization of glycogen during metamorphosis of the medfly Ceratitis capitata.

There are no recent reports focusing on insect glycogen metabolism that take the advances made in mammalian and yeast systems into account. Moreover, little is known about glycogen synthesis and degradation during insect metamorphosis. The biosynthesis and mobilization of insect glycogen were measured during the larva to adult transition in the Medfly, Ceratitis capitata. The glycogen accumulated by larva decreased to reach almost undetectable levels at the beginning of the pupation process. Histological preparations of 40 h muscles and fat body confirmed a low glycogen content, in contrast with high glycogen images in third larva tissues. After 40 h, glycogen was synthesized de novo and accumulates up to adult ecdysis. We obtained the metamorphosis-dependent profiles of phosphorylase, glycogen synthase, and a glycogenin-like protein. This novel insect glycogen initiator protein (the first measured in an arthropod) appeared to be similar to the homologous enzymes from vertebrates and yeast. We have correlated these results with other biochemical events and anatomical landmarks to understand the use of storage carbohydrates during the sequence of metamorphosis events.

Amylases↗
PubMed1999

An extended dorsal island skin flap with multiple vascular territories in the rat: A new skin flap model.

BACKGROUND: The use of various animal skin flap models can lead to difficulty in the interpretation of experimental findings. Establishment of an axial-pattern flap model with predictable necrosis is desirable for the study of the flap pathophysiology. MATERIALS AND METHODS: Twenty rats were injected with a lead oxide, gelatin, and water mixture through the carotid artery to investigate the cutaneous vascular anatomy. Each cutaneous perforator on the rat dorsum was dissected to its source artery. The skin was removed and radiographed to define its vascular architecture. On the basis of the initial angiographic data, an extended dorsal island skin flap (based on the unilateral deep circumflex iliac artery) measuring up to 8 x 9 cm was designed in 10 rats to assess the viability of the flap. The boundaries of the flap are defined by anatomical landmarks to standardize the flap for rats of different sizes. The upper margin was located at the level of the tip of the scapula and the lower margin at a level 2 cm below the iliac crest. All flaps were observed for 7 days postoperatively and the surviving flap area was calculated as a percentage of total flap dimensions using the paper template technique. RESULTS: Most of the skin of the rat dorsum is supplied by three arteries: the deep circumflex iliac artery (DCIA), the posterior intercostal arteries (PIA), and the lateral thoracic artery (LTA). The DCIA anastomoses with the ipsilateral PIA and the contralateral PIA and DCIA. The average percentage survival of the skin flap is 70.5 +/- 4.8% (mean +/- SD). CONCLUSIONS: The extended dorsal island skin flap has a consistent vasculature and has a predictable distal necrosis area. This new model is felt to be appropriate for skin flap physiological studies.

Animals↗
PubMed1999

LOFA: software for individualized localization of functional MRI activity.

Although PET, SPECT, and fMRI studies have led to significant advances in functional mapping of the human brain, precise localization and quantification of activity in individual brains require additional procedures. Difficulties to be addressed by a localization strategy are: resolution of individual anatomic differences, differentiation of functional activity in closely juxtaposed brain regions, and management of multiple intricately shaped 3D anatomic structures. In this paper, we describe a localization tool, LOFA, which addresses these problems by forming ROIs with a user-driven interface. Using LOFA, complex 3D anatomy can be defined through open or closed loops and anatomic landmarks. Resulting partitions can be overlaid on top of each other to form multiple regions of interest (ROIs), and functional activity in these ROIs can be extracted individually, one after the other. LOFA introduces important paradigmatic advances over the other ROI analysis methods. The toolbox is interactive, fully compatible with AFNI (MCW), and requires Pv-Wave (VNI Inc.) license to run.

Brain↗
PubMed2001

Three-dimensional probabilistic atlas of the human orbitofrontal sulci in standardized stereotaxic space.

A quantitative analysis of the variability of human orbitofrontal anatomical landmarks is required if one is to describe properly the location of functional or structural changes within this brain region. The present study investigated the orbitofrontal sulci in 100 normal adult human cerebral hemispheres using magnetic resonance images that were transformed into the standardized proportional stereotaxic space most commonly used, that of Talairach and Tournoux (1988). Four orbitofrontal sulci were identified and marked on each hemisphere: the olfactory, the medial, the lateral, and the transverse orbital sulci. Probability maps were then constructed for each sulcus. These maps provide a statistical description of the variability of the location of each orbitofrontal sulcus within the three-dimensional coordinate system of Talairach and Tournoux (1988). These probability maps may be directly compared with any image transformed into the same standardized space, providing a valuable tool for identifying and describing the location of functional or structural changes in the orbitofrontal region of the human brain.

Adult↗
PubMed2001

A parametric fMRI study of overt and covert shifts of visuospatial attention.

It has recently been demonstrated that a cortical network of visuospatial and oculomotor control areas is active for covert shifts of spatial attention (shifts of attention without eye movements) as well as for overt shifts of spatial attention (shifts of attention with saccadic eye movements). Studies examining activity in this visuospatial network during attentional shifts at a single rate have given conflicting reports about how the activity differs for overt and covert shifts. To better understand how the network subserves attentional shifts, we performed a parametric study in which subjects made either overt attentional shifts or covert attentional shifts at three different rates (0.2, 1.0, and 2.0 Hz). At every shift rate, both overt and covert shifts of visuospatial attention induced activations in the precentral sulcus, intraparietal sulcus, and lateral occipital cortex that were of greater amplitude for overt than during covert shifting. As the rate of attentional shifts increased, responses in the visuospatial network increased in both overt and covert conditions but this parametric increase was greater during overt shifts. These results confirm that overt and covert attentional shifts are subserved by the same network of areas. Overt shifts of attention elicit more neural activity than do covert shifts, reflecting additional activity associated with saccade execution. An additional finding concerns the anatomical organization of the visuospatial network. Two distinct activation foci were observed within the precentral sulcus for both overt and covert attentional shifts, corresponding to specific anatomical landmarks. We therefore reappraise the correspondence of these two precentral areas with the frontal eye fields.

Adult↗