Resection of benign sciatic notch dumbbell-shaped tumors

2006 ◽  
Vol 105 (6) ◽  
pp. 873-880 ◽  
Author(s):  
Robert J. Spinner ◽  
Toshiki Endo ◽  
Kimberly K. Amrami ◽  
Eric J. Dozois ◽  
Dusica Babovic-Vuksanovic ◽  
...  
Keyword(s):  
High Resolution ◽  
Sciatic Nerve ◽  
Mr Imaging ◽  
Neurological Deficits ◽  
Leg Pain ◽  
Preoperative Imaging ◽  
Imaging Data ◽  
Cross Sectional ◽  
Sciatic Notch ◽  
One Stage

Object The operative management of combined intrapelvic and extrapelvic sciatic notch dumbbell-shaped tumors is challenging. The relatively rare occurrence of these tumors and the varied extent of disease have made it difficult for surgeons to establish definitive surgical indications or predict favorable neurological outcomes based on preoperative imaging data. Methods In the past 3 years, the authors treated five patients presenting with radiating leg pain as a result of benign sciatic notch dumbbell-shaped tumors. These tumors in three patients with unilateral leg symptoms were considered unresectable by other neurosurgeons because of presumed direct intrinsic neural involvement. After high-resolution magnetic resonance (MR) imaging demonstrated that the extensive tumors were separate from the sciatic nerve and the lumbosacral plexus, however, these patients underwent a combined one-stage transabdominal and posterior transgluteal complete resection. Normal neurological status was maintained postoperatively in these three patients, and after more than 1 year of postoperative follow up, there were no tumor recurrences. In two patients with bilateral symptoms and extensive tumor burden, serial MR images showed that innumerable tumors directly involved the entire cross-sectional area of the sciatic nerves and extended longitudinally to the lumbosacral plexuses. Tumor debulking or resection in these patients would have resulted in neurological deficits and would not have addressed their neuropathic pain, and therefore no surgery was performed. These two patients were treated pharmacologically and advised to monitor their tumor status over the course of their lifetimes in case of malignant transformation of the tumor. Conclusions A combined one-stage transabdominal and transgluteal approach allows safe resection of selected benign but extensive sciatic notch tumors. High-resolution MR imaging is a useful tool in the management of these tumors because it allows the surgeon to visualize the anatomical relationships of the tumor to the sciatic nerve. The authors believe that as this imaging technology advances, it will provide surgeons with a method to predict definitively which sciatic notch tumors displace rather than directly involve the sciatic nerve, and therefore indicate which tumors can be resected safely and completely.

scholarly journals Error analysis for a free-hand three-dimensional ultrasound system for neuronavigation

1999 ◽  
Vol 6 (3) ◽  
pp. E7 ◽  
Author(s):  
Alexander Hartov ◽  
Symma D. Eisner ◽  
W. Roberts ◽  
Keith D. Paulsen ◽  
Leah A. Platenik ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Three Dimensional ◽  
Ultrasound Image ◽  
Imaging Study ◽  
Ct Scanning ◽  
Preoperative Imaging ◽  
Ultrasound Images ◽  
Imaging Data ◽  
Extensive Evaluation ◽  
Ultrasound System

Image-guided neurosurgery that is directed by a preoperative imaging study, such as magnetic resonance (MR) imaging or computerized tomography (CT) scanning, can be very accurate provided no significant changes occur during surgery. A variety of factors known to affect brain tissue movement are not reflected in the preoperative images used for guidance. To update the information on which neuronavigation is based, the authors propose the use of three-dimensional (3-D) ultrasound images in conjunction with a finite-element computational model of the deformation of the brain. The 3-D ultrasound system will provide real-time information on the displacement of deep structures to guide the mathematical model. This paper has two goals: first, to present an outline of steps necessary to compute the location of a feature appearing in an ultrasound image in an arbitrary coordinate system; and second, to present an extensive evaluation of this system's accuracy. The authors have found that by using a stylus rigidly coupled to the 3-D tracker's sensor, they were able to locate a point with an overall error of 1.36 ± 1.67 mm (based on 39 points). When coupling the tracker to an ultrasound scanhead, they found that they could locate features appearing on ultrasound images with an error of 2.96 ± 1.85 mm (total 58 features). They also found that when registering a skull phantom to coordinates that were defined by MR imaging or CT scanning, they could do so with an error of 0.86 ± 0.61 mm (based on 20 coordinates). Based on their previous finding of brain shifts on the order of 1 cm during surgery, the accuracy of their system warrants its use in updating neuronavigation imaging data.

Intraoperative three-dimensional visualization in microvascular decompression

2007 ◽  
Vol 107 (6) ◽  
pp. 1137-1143 ◽  
Author(s):  
Levent Tanrikulu ◽  
Peter Hastreiter ◽  
Regina Troescher-Weber ◽  
Michael Buchfelder ◽  
Ramin Naraghi
Keyword(s):  
Mr Imaging ◽  
Microvascular Decompression ◽  
3D Visualization ◽  
Cranial Nerves ◽  
Preoperative Imaging ◽  
Neurosurgical Procedures ◽  
Vascular Compression ◽  
Neurovascular Compression ◽  
Imaging Data ◽  
Neurovascular Structures

Object The authors systematically analyzed 3D visualization of neurovascular compression (NVC) syndromes in the operating room (OR) during microvascular decompression (MVD). Methods A total of 50 patients (26 women and 24 men) with trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GN) were examined and underwent MVD. Preoperative imaging of the neurovascular structures was performed using constructive interference in the steady state magnetic resonance (CISS MR) imaging, which consisted of 2D image slices. The 3D visualization of the neurovascular anatomy is generated after segmentaion of the CISS MR imaging in combination with direct volume rendering (DVR). The 3D representations were stored on a personal computer (PC) that was mounted on a mobile unit and transferred to the OR. During surgery, 3D visualization was applied by the surgeon with remotely controlled plasma-sterilized devices such as a wireless mouse and keyboard. The position of the 3D visualized neurovascular structures at the PC monitor was determined according to the intraoperative findings observed through the operating microscope. Results The system was stable during all neurosurgical procedures, and there were no operative or technical complications. Interactive adjustment of the 3D visualization guided by the view through the microscope permitted observation of the neurovascular relationships at the brainstem. Vessels covered by the cranial nerves could be noninvasively viewed by intraoperative 3D visualization. Postoperatively, the patients with TN and GN experienced pain relief, and the patients with HFS attained resolution of their facial tics. Vascular compression of nerves was explored in all 50 patients during MVD. Intraoperative 3D visualization delineated the compressing vessels and respective cranial nerves in 49 (98%) of 50 patients. Conclusions Interactive 3D visualization by DVR of high-resolution MR imaging data offered the opportunity for noninvasive virtual exploration of the neurovascular structures during surgery. An extended global survey of the neurovascular relationships was provided during MVD in each case. The presented method proved to be extremely advantageous for optimizing microneurosurgical procedures, supporting superior safety and improving the operative results when compared with the conventional strategy. This modality proved to be a very valuable teaching instrument and ensured the improvement of neurosurgical quality.

scholarly journals Reference values for the cross-sectional area of the normal sciatic nerve using high-resolution ultrasonography

2021 ◽  
Vol 21 (85) ◽  
pp. e95-e104
Author(s):  
Kunwar Pal Singh ◽  
◽  
Prabhjot Singh ◽  
Kamlesh Gupta
Keyword(s):  
High Resolution ◽  
Sciatic Nerve ◽  
Reference Values ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
The Mean ◽  
Sciatic Nerves ◽  
The Cross ◽  
High Resolution Ultrasonography

Aim: High-resolution ultrasonography is a new and promising technique to evaluate peripheral and spinal nerves. Its validity as a diagnostic tool in neurological diseases has been demonstrated in adults. The aims of study were to establish the reference values for the cross-sectional area of the normal sciatic nerve on high-resolution ultrasonography, and to determine the relationship between the cross-sectional area of the normal sciatic nerve and the subjects’ age, gender, height (in cm), weight (in kg), and body mass index. Material and methods: Two hundred subjects of both genders and above 18 years of age were studied with high-resolution ultrasonography. The subjects had no history of peripheral neuropathy or trauma to the lower limb. The cross-sectional areas of the normal sciatic nerves were obtained at two different levels in both lower limbs. The mean cross-sectional areas of the sciatic nerves were measured at two different levels, one located at 1 cm above the bifurcation of the sciatic nerve into the tibial and common peroneal nerves, and the other 4 cm above the bifurcation of the sciatic nerve into the tibial and common peroneal nerves. Results: A positive correlation of the mean cross-sectional area was established with height, weight, and body mass index. Women had smaller cross-sectional areas of the normal sciatic nerves than men at both measuring sites. No significant relationship was established with the age of the subjects. Conclusions: The established reference values of the cross-sectional area of the sciatic nerve can facilitate the analysis of pathological nerve conditions.

scholarly journals 281 Evaluating a Diagnostic Algorithm for Adult Appendicitis – A Quality Improvement Project

2021 ◽  
Vol 108 (Supplement_2) ◽  
Author(s):  
B E Zucker ◽  
F Loro ◽  
A Tyer ◽  
J Shabbir ◽  
M Finch-Jones ◽  
...  
Keyword(s):  
Quality Improvement ◽  
Diagnostic Algorithm ◽  
Quality Improvement Project ◽  
Preoperative Imaging ◽  
Imaging Data ◽  
Cross Sectional ◽  
Improvement Project ◽  
Cross Sectional Imaging ◽  
Time Periods ◽  
Sectional Imaging

Abstract Introduction Diagnosing appendicitis remains challenging, despite being the most common surgical emergency. We conducted a single-centre mixed method quality improvement project to assess the validity of a diagnostic algorithm for appendicitis and the diagnostic impact of increasing cross-sectional imaging during the Covid-19 pandemic. Method Adult histology reports and preoperative imaging data were retrospectively retrieved for patients operated on between 1/7/19-31/12/19 (‘baseline data’) and an appendicitis diagnostic algorithm was developed. Imaging and risk stratification data were prospectively collected, as part of a national audit, between 20/03/30-23/6/20 for all adult appendicitis patients. This data was used to evaluate the efficacy of the proposed diagnostic algorithm. Use of imaging and histological diagnoses was compared between datasets. Results 194 patients were included across both time periods. The rate of cross-sectional imaging increased from 36.6% to 76% and the normal appendicectomy rate (NAR) decreased from 5.22% to 2.4%. Thirty-six percent of patients in the latter time period were not managed in accordance with the proposed algorithm. The proposed diagnostic algorithm may have prevented up to 87.5% of normal appendicectomies across both time periods. Conclusions Increasing cross-sectional imaging was associated with a decrease in the NAR. The use of the proposed diagnostic algorithm may have reduced the NAR further.

High-resolution scanning electron microscopy of thin-film magnetic media of magnetic recording disk

1992 ◽  
Vol 50 (2) ◽  
pp. 1334-1335
Author(s):  
K. Ogura ◽  
H. Nishioka ◽  
N. Ikeo ◽  
T. Kanazawa ◽  
J. Teshima
Keyword(s):  
Thin Film ◽  
Fine Structure ◽  
High Resolution ◽  
Magnetic Recording ◽  
High Performance ◽  
Magnetic Hysteresis ◽  
Grain Structure ◽  
Magnetic Media ◽  
Cross Sectional ◽  
Resolution Observation

Structural appraisal of thin film magnetic media is very important because their magnetic characters such as magnetic hysteresis and recording behaviors are drastically altered by the grain structure of the film. However, in general, the surface of thin film magnetic media of magnetic recording disk which is process completed is protected by several-nm thick sputtered carbon. Therefore, high-resolution observation of a cross-sectional plane of a disk is strongly required to see the fine structure of the thin film magnetic media. Additionally, observation of the top protection film is also very important in this field.Recently, several different process-completed magnetic disks were examined with a UHR-SEM, the JEOL JSM 890, which consisted of a field emission gun and a high-performance immerse lens. The disks were cut into approximately 10-mm squares, the bottom of these pieces were carved into more than half of the total thickness of the disks, and they were bent. There were many cracks on the bent disks. When these disks were observed with the UHR-SEM, it was very difficult to observe the fine structure of thin film magnetic media which appeared on the cracks, because of a very heavy contamination on the observing area.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

High-Resolution Cryo-Electron Microscopy of Biological Macromolecules

1990 ◽  
Vol 48 (1) ◽  
pp. 126-127
Author(s):  
Yoshinori Fujiyoshi
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Diffraction Pattern ◽  
Superfluid Helium ◽  
Copper Phthalocyanine ◽  
Optical Diffraction ◽  
Irradiation Damage ◽  
Biological Macromolecules ◽  
Cross Sectional ◽  
Instrumental Resolution

The resolution of direct images of biological macromolecules is normally restricted to far less than 0.3 nm. This is not due instrumental resolution, but irradiation damage. The damage to biological macromolecules may expect to be reduced when they are cooled to a very low temperature. We started to develop a new cryo-stage for a high resolution electron microscopy in 1983, and successfully constructed a superfluid helium stage for a 400 kV microscope by 1986, whereby chlorinated copper-phthalocyanine could be photographed to a resolution of 0.26 nm at a stage temperature of 1.5 K. We are continuing to develop the cryo-microscope and have developed a cryo-microscope equipped with a superfluid helium stage and new cryo-transfer device.The New cryo-microscope achieves not only improved resolution but also increased operational ease. The construction of the new super-fluid helium stage is shown in Fig. 1, where the cross sectional structure is shown parallel to an electron beam path. The capacities of LN2 tank, LHe tank and the pot are 1400 ml, 1200 ml and 3 ml, respectively. Their surfaces are placed with gold to minimize thermal radiation. Consumption rates of liquid nitrogen and liquid helium are 170 ml/hour and 140 ml/hour, respectively. The working time of this stage is more than 7 hours starting from full LN2 and LHe tanks. Instrumental resolution of our cryo-stage cooled to 4.2 K was confirmed to be 0.20 nm by an optical diffraction pattern from the image of a chlorinated copper-phthalocyanine crystal. The image and the optical diffraction pattern are shown in Fig. 2 a, b, respectively.

Sign in / Sign up

Export Citation Format

Share Document