Biomedical subjects

G J Wiet

Publications and source records attributed to G J Wiet.

12 recordsLinked to original sources

PubMed1998

Using advanced simulation technology for cranial base tumor evaluation.

Skull base tumors are considered one of the most difficult pathologic entities to diagnose and treat. The physician is heavily dependent on imaging studies to determine the best form of treatment. As imaging technology becomes more advanced, the physician will need to be able to intuitively explore the complex data. Such intuitive exploration requires the use of high performance computer hardware and software. Issues related to this concept and a summary of current work in this area are presented.

Computer Systems↗

PubMed1998

Virtual environments. Surgical simulation in otolaryngology.

Advanced technology in the form of computer-generated surgical simulation has tremendous potential as an adjunctive training aid to residents in training and experienced surgeons. This article explores the state-of-the-art in surgical simulation for otolaryngologists and future directions in this area.

Computer Simulation↗

PubMed1998

Functional endoscopic sinus surgery training simulator.

OBJECTIVE/HYPOTHESIS: To determine the efficacy of a haptic (force feedback) device and to compare isosurface and volumetric models of a functional endoscopic sinus surgery (FESS) training simulator. STUDY DESIGN: A pilot study involving faculty and residents from the Department of Otolaryngology at The Ohio State University. METHODS: Objective trials evaluated the haptic device's ability to perceive three-dimensional shapes (stereognosis) without the aid of image visualization. Ethmoidectomy tasks were performed with both isosurface and volumetric FESS simulators, and surveys compared the two models. RESULTS: The haptic device was 77% effective for stereognosis tasks. There was a preference toward the isosurface model over the volumetric model in terms of visual representation, comfort, haptic-visual fidelity, and overall performance. CONCLUSIONS: The FESS simulator uses both visual and haptic feedback to create a virtual reality environment to teach paranasal sinus anatomy and basic endoscopic sinus surgery techniques to ear, nose, and throat residents. The results of the current study showed that the haptic device was accurate in and of itself, within its current physical limitations, and that the isosurface-based simulator was preferred.

Computer Simulation↗

PubMed1998

A comparative analysis of integrating visual representations with haptic displays.

As further advances in visual display technologies and force feedback devices are integrated in virtual systems, questions remain: What level of reality does the system provide to the user? Is the environment convincing enough to engage the user and to maximize transfer? Are the visual and haptic displays fully integrated to provide seamless operation in the simulated environment? Does the system provide not only the ability to navigate through a simulated environment, but also realistic interaction with instrumentation and structures? We report on our advances in developing a virtual simulation system for training in functional endoscopic sinus surgery (FESS). Specifically, we will present work on subject trials exploring the realism provided by integrated visual and haptic displays, and compare and contrast surface vs. volume representation for presenting realistic models of the anatomy for surgical interaction.

Computer Simulation↗

PubMed1997

Surgical correction of obstructive sleep apnea in the complicated pediatric patient documented by polysomnography.

OBJECTIVE: Evaluate the effectiveness of surgical treatment of obstructive sleep apnea in a diverse population of children. DESIGN: A retrospective case series of pre and post operative polysomnograms (PSG) of pediatric patients with obstructive sleep apnea (OSA). SETTING: Tertiary care children's hospital. PATIENTS: 48 patients in whom sleep studies were performed pre-operatively for either an unclear history and/or physical findings or complicated OSA. Thirteen patients had no complicating medical factors, 35 patients had various associated medical problems, including 20 with morbid obesity, five with Down syndrome, four with asthma, two with cerebral palsy, and four other. The average age was 7.5 years with a range of 1.5-20 years. INTERVENTIONS: Thirty-one patients had a tonsillectomy and adenoidectomy (T and A) only, 13 had T and A with uvulopalatopharyngoplasty (UPPP), and three had tonsillectomy and UPPP. MAIN OUTCOME MEASURES: Pre and postoperative PSG results including apnea/hypopnea index (AHI), percent of sleep with oxygen saturation below 90%, and percent sleep time with end-tidal pCO2 > 50. RESULTS: The mean pre-operative (AHI) was 27 +/- 4 (mean +/- S.E.M.) and post operatively was 6 +/- 1 (P < 0.001). Twenty six of 48 (54%) had a postoperative AHI of less than five. Pre-operative percent of sleep with oxygen saturation below 90% was 17.9 +/- 4.5%, post-operatively it was 1.4 +/- 0.1% (P < 0.001). Pre-operative percent sleep time with end-tidal pCO2 > 50 was 22.3 +/- 3.4%, post operatively it was 12.6 +/- 2.9% (P < 0.01). UPPP was performed more commonly in patients with Down syndrome. There was a trend toward more improvement in patients who had T and performed than those undergoing UPPP (post op AHI of 4.7 vs. 7.4 respectively). CONCLUSIONS: Tonsillectomy, adenoidectomy and UPPP are effective in the treatment of OSA in a diverse group of pediatric patients. Patients with asthma, cerebral palsy, Down syndrome, morbid obesity, and hereditary syndromes all improved significantly with surgical management.

Adenoidectomy↗

PubMed1997

Airway management of neonates with antenatally detected head and neck anomalies.

Five cases of prenatally detected neck masses that had a potential for airway obstruction at birth are described. The various options for management of the airway are discussed, including using maternal-fetal circulation until intubation, rigid bronchoscopy, tracheotomy, cyst aspiration, or extracorporeal membrane oxygen support. Congenital abnormalities involving the fetal face or neck are extremely rare. With technical advances in ultrasonography, these masses were first noted on prenatal ultrasound in the late 1970s. Before that period, they were detected at delivery. These masses are solid or cystic and may cause asphyxia because of airway obstruction at the time of delivery. The survivability of these neonates without immediate intervention at birth is 0% to 20%. If a neck mass is detected in the fetus by prenatal ultrasonography, then a strategic plan for these types of cases should be developed early in the prenatal period. The airway management plan should be tailored for each individual case. Coordination and the expertise of an obstetrician, neonatologist, anesthesiologist, and pediatric otolaryngologist are needed to manage these complex situations.

Adult↗

PubMed1997

A volumetric approach to virtual simulation of functional endoscopic sinus surgery.

Advanced display technologies have made the virtual exploration of relatively complex models feasible in many applications. Unfortunately, only a few human interfaces allow natural interaction with the environment. Moreover, in surgical applications, such realistic interaction requires real-time rendering of volumetric data-placing an overwhelming performance burden on the system. We report on a collaboration of an interdisciplinary group developing a virtual reality system that provides intuitive interaction with volume data by employing real-time volume rendering and force feedback (haptic) sensations. We describe our rendering methods and the haptic devices and explain its utility of this system in the real-world application of Endoscopic Sinus Surgery (ESS) simulation.

Computer Simulation↗

PubMed1996

Cranial base tumor visualization through high-performance computing.

Tumors of the skull base in general are considered among the more difficult head and neck pathological entities to treat surgically; some surgeons, in fact, consider lesions in this area inoperable. The most appropriate and safest surgical approach to lesions of the anterior and lateral skull base can be devised only with accurate and precise pre-operative assessment. The literature demonstrates the constant evolution of and search for more efficient less invasive, and safe surgical approaches to this region. With the development of a more exact three-dimensional, interactive anatomical "road map" for each patient's disease and anatomy, the skull base surgeon can not only achieve a more accurate pre-operative assessment leading to a less invasive and less morbid approach, but also can continue to develop and refine new approaches without fear of actual morbidity and mortality. An interdisciplinary team approach, the advent and continued development of faster high performance computers, and the development of new and innovative rendering algorithms can lead to surgical simulation. A prototype of an interactive system has been developed. The system will be iteratively modified through a stepwise evaluation of its clinical usefulness by continually reassessing the system with clinical trials. The current state of the system and the potential benefits are presented.

Brain Mapping↗

PubMed1990

Enzymes of transmitter and energy metabolism in rat middle ear and extraocular muscles.

To further investigate the peculiar characteristics of the middle ear and extraocular muscles, compared to the extensively studied skeletal muscles of the limbs, activities of enzymes of transmitter and energy metabolism were measured in homogenates of these muscles from albino and pigmented rats. These activities were compared to those for a masticatory muscle and for three hindlimb muscles chosen for their preponderance of either slow oxidative, fast glycolytic, or fast oxidative glycolytic fibers. Activities of the neuromuscular transmitter enzymes choline acetyltransferase and acetylcholinesterase were relatively very high in the extraocular and middle ear muscles. The activity of malate dehydrogenase, an enzyme of oxidative energy metabolism, was as high in the extraocular, masticatory and stapedius muscles as in the oxidative hindlimb muscles, but was lower in tensor tympani. The activity of lactate dehydrogenase, an enzyme of glycolytic energy metabolism, was remarkably low in both middle ear muscles. The results are consistent with high innervation density in the extraocular and middle ear muscles, and highly oxidative metabolism in the extraocular and stapedius muscles. Metabolic differences between the stapedius and tensor tympani suggest a relatively more active role for the former in the function of the rat middle ear.

Animals↗

PubMed1990

Quantitative distributions of aspartate aminotransferase and glutaminase activities in the guinea pig cochlea.

Distributions of aspartate aminotransferase and glutaminase activities in the guinea pig cochlea have been examined with use of quantitative microchemical techniques to evaluate their roles in cochlear energy metabolism and neurotransmission. Other enzyme activities analyzed were those of choline acetyltransferase and malate dehydrogenase. It is concluded that aspartate aminotransferase activity appears to be especially concerned with cochlear energy metabolism, while glutaminase activity may function in transmitter metabolism in the guinea pig cochlea. Neither enzyme shows a clear association with the olivocochlear bundle.

Animals↗

PubMed1990

Enzymes of transmitter and energy metabolism in cat middle ear muscles.

Activities of the enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), which metabolize the neuromuscular transmitter acetylcholine, and malate and lactate dehydrogenase (MDH and LDH), enzymes of oxidative and glycolytic energy metabolism, respectively, were measured in the middle ear muscles of the cat. For comparison, the same enzyme activities were measured in extraocular muscle tissue and in three hindlimb muscles rich in either slow oxidative (soleus), fast glycolytic (white part of vastus lateralis), or fast oxidative glycolytic (plantaris) muscle fibers. ChAT and AChE activities were much higher in middle ear muscles than in hindlimb muscles, consistent with a denser neuromuscular innervation, as in extraocular muscles. By contrast, MDH and LDH activities were remarkably low in the middle ear muscles, lower than in any of the hindlimb muscles or the extraocular muscles. Denervation of the stapedius muscle by peripheral transection of the facial nerve resulted in decreases in all four enzyme activities without associated changes in the tensor tympani. Surgical ablation of the peripheral facial nerve supply to the stapedius muscle appears to be a feasible option for producing its denervation. The results suggest some rather specialized chemical characteristics for the middle ear muscles.

Acetylcholinesterase↗

PubMed1986

Quantitative distributions of aspartate aminotransferase and glutaminase activities in the rat cochlea.

The intra-cochlear distributions of aspartate aminotransferase and glutaminase, prominent enzymes of aspartate and glutamate metabolism, have been studied by quantitative microchemical techniques. Also measured was choline acetyltransferase, the enzyme synthesizing acetylcholine, and a marker for the olivocochlear bundle. Aspartate aminotransferase activity was highest in the stria vascularis, about half this high in the organ of Corti synaptic (hair cell) zones, somewhat lower in the organ of Corti non-synaptic (Hensen's cell) zones, lower yet in Reissner's and lowest in the tectorial membrane. Glutaminase, on the other hand, had its highest activity in synaptic zones, about a third of that activity in the organ of Corti non-synaptic zones, and a barely detectable activity in Reissner's and tectorial membranes, and stria vascularis. Seven days after transection of the olivocochlear bundle, no significant difference was found between lesion- and control-side aspartate aminotransferase or glutaminase activities, even though no choline acetyltransferase activity remained in the lesion-side of the organ of Corti. Both the distribution of aspartate aminotransferase activity and the lesion results would seem to implicate it in energy more so than neurotransmitter metabolism. The distribution of glutaminase activity could be consistent with a role in neurotransmission; however, the lesion data were unable to demonstrate a specific association with the olivocochlear bundle.

Animals↗