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A Dietz

Publications and source records attributed to A Dietz.

At least 19 recordsLinked to original sources
PubMed2007

[Rare sialadenoma papilliferum in the hard palate: case report and survey of the literature].

Sialadenoma papilliferum is a rare tumour of the salivary glands that usually occurs in the oral cavity. Following the course of the salivary glands of the oral mucosa, the hard and soft palate are the most common locations of this tumor. In the international literature, only a few case reports about this entity can be found. We present a 63-year-old patient with a sialadenoma papilliferum accidentally found during diagnostic procedures for progredient dysphagia. Suffering from infrabifurcal cancer of the oesophagus, the patient had undergone partial oesophagectomy 1 year before. Histological verification was performed with a tumor biopsy at the border of hard and soft palate, on the right side. This case is compared with 39 further cases reported in the literature. The therapy of choice is resection of the tumor. Because of the high frequency of recurrence, in sano resection should be planned.

Adenoma↗
PubMed2007

[Manipulator assisted endoscope guidance in functional endoscopic sinus surgery: proof of concept].

BACKGROUND: Functional endoscopic sinus surgery (FESS) is characterized by single-handed preparation and guidance of the endoscope by the nondominant hand. This results in an additional extension of operation time by up to 15% and ergonomic deficits. The aim of this study is the conception of an automated assistance system for FESS in view of the following questions: (1) Which degree of surgical automation is suitable for FESS? (2) Which design is suitable? (3) What are the properties of the technical system (planning, time, accuracy, precision) of the selected system? (4) Does the system offer potential for a clinical application? METHODS: In all 49 FESS were analyzed for surgical workflows. Measurement of the maximum forces within FESS was performed with 40 trials on an anatomical model. Three different mechanical systems were used in ten FESS and evaluated using the ICCAS Human-Machine Evaluation Scale. For realization of automated endoscope guidance an engine-driven and -braked manipulator (PA10-6c, Mitsubishi, Japan) was used. The technical parameters determined were expenditure of time for the preoperative planning of workspace, surgical accuracy and precision of the intraoperative endoscope positioning, maximal forces, and time. RESULTS: Concept-conditioned instrument changes amount to an average of 41.1 and 18.9% (5.21 min) time requirement for each FESS side. Maximum forces on the mucous membrane during a conventional FESS were measured at 9.8 N (5.9-9.8). Usability of the mechanical endoscope holder was estimated in 18 of 20 cases to be inferior to the standard procedure. The time needed for segmenting the intranasal workspace was 15.2 min (10.0-23.0). The maximum deviation of the automatically driven endoscope from a planned position amounted to 0.85 mm (manually 4.64 mm). The maximum force was measured with 1.1 N in the z direction (manually 9.8 N). Automated guidance of the endoscope to an intranasal position needed 7.25 s (6.4-7.9); manually 12.64 s (5.9-43.0). CONCLUSION: Guidance of the endoscope for FESS by an automated motor-driven system is possible. The conception which is based on workflow analysis favors a system with automatic definition of the workspace and a manual movement of the endoscope. The examined system offers a potential for clinical application. Definition of the automation level and development of a man-machine interface is more important than selection or reconstruction of a special manipulator for endoscope guidance in FESS from a surgical point of view.

Endoscopes↗
PubMed2007

[Acute mastoiditis today].

Acute mastoiditis is an acute inflammation of the mastoid process with bone erosion. It is a complication of acute otitis media, which is rare but with increasing incidence. Distinct characteristics are an erythema and oedematous swelling of the skin of the mastoid process. A fluctuant swelling points to a subperiosteal abscess. Laboratory examination and imaging only support the diagnostics. Therapy involves obligatory systemic antibiotic treatment. At the beginning of the inflammation a paracentesis can be sufficient. A mastoidectomy must be carried out if clear signs of an osseous necrolysis, such as a subperiosteal abscess, are present. The most frequent causative agents are gram positive cocci. Intraoperative smears are best suitable for microbiological diagnostics. Complications of acute mastoiditis are encroachments of the inflammation on neighbouring structures of the mastoid. In such cases a tomography is indicated and therapy is usually surgical.

Acute Disease↗
PubMed2007

[Role of epigenetics in the carcinogenesis of head and neck carcinomas - possible new targeted therapy?].

In search of new targeted therapies for squamous cell carcinoma of the head neck (HNSCC), a better understanding of the carcinogenesis is of outmost importance. Recent studies show that not only genetic but also epigenetic alterations initiate the multistep process of tumordevelopment. Epigenetic changes lead to altered gene expression without alterations of the DNA sequence. The best characterized epigenetic change is the methylation of the promoter region of genes, especially of tumorsuppressor genes. The methylation of the promoter region blocks the promoter and therefore represses transcription. The loss of the gene products of tumorsuppressor genes leads to increased proliferation and decreased apoptosis. Methylation of tumorsuppressor genes was shown in precancerous lesions of HNSCC, which emphasizes the importance of methylation as an early biomarker. Several studies of tumor cell cultures show reactivated expression of proteins and as a result reduction of proliferation and induction of apoptosis after treatment with demethylating agentens. This presents a very promising new option for a targeted therapy.

Antimetabolites, Antineoplastic↗
PubMed2006

Proteomic analysis reveals successive aberrations in protein expression from healthy mucosa to invasive head and neck cancer.

Development of head and neck squamous cell carcinoma (HNSCC) is a multistep process and in many cases involves a phenomenon coined 'field cancerization'. In order to identify changes in protein expression occurring at different stages of tumorigenesis and field cancerization, we analysed 113 HNSCCs and 73 healthy, 99 tumor-distant and 18 tumor-adjacent squamous mucosae by SELDI-TOF-MS on IMAC30 ProteinChip Arrays. Forty-eight protein peaks were differentially expressed between healthy mucosa and HNSCC. Calgizarrin (S100A11), the Cystein proteinase inhibitor Cystatin A, Acyl-CoA-binding protein, Stratifin (14-3-3 sigma), Histone H4, alpha- and beta-Hemoglobin, a C-terminal fragment of beta-hemoglobin and the alpha-defensins 1-3 were identified by mass spectrometry. The alpha-defensins showed various alterations in expression as validated by immunohistochemistry (IHC). Supervised prediction analysis revealed excellent classification of healthy mucosa (94.5% correctly classified) and tumor samples (92.9% correctly classified). Application of this classifier to the tumor-adjacent and tumor-distant mucosa samples disclosed dramatic changes: only 59.6% of the tumor-distant biopsies were classified as normal, 27.3% were predicted as aberrant or HNSCC. Strikingly, 72% of the tumor-adjacent mucosae were predicted as aberrant. These data provide evidence for the existence of genetically altered fields with inconspicuous histology. Comparison of the protein profiles in the tumor-distant-samples with clinical outcome of 32 patients revealed a significant association between aberrant profiles with tumor relapse events (P=0.018; Fisher's exact test, two-tailed). We conclude that proteomic profiling in conjunction with protein identification greatly outperforms histopathological diagnosis and may have significant predictive power for clinical outcome and personalized risk assessment.

Amino Acid Sequence↗
PubMed2006

[Improved accuracy and precision of the automated shaver (navigated control) in functional endoscopic sinus surgery].

BACKGROUND: The feasibility of a navigate-controlled Shaver for the paranasal sinus surgery was proven in an initial study. Deficits showed up in the conversion of the planed cavity. Goal of this study is (1) the development and evaluation of a FESS demonstrator for the investigations to the surgical accuracy and (2) the evaluation of the resulting surgical accuracy for registration and conversion of the work space with an improved rigidity of the Shaver and a completely revised study design. METHODS: As a demonstrator for the navigate-controlled resection of a volume through the Shaver a two-piece plastic head with an anatomical head and soft tissue model was designed. The investigation of the surgical accuracy takes place with 417 measurements to 4 different fiducial markers on the demonstrator head. The measurements for the deviation of the resulting cavity from the planned volume was realised with a work space by 24 x 24 x 30 mm. The 5 walls of the cavity were seized with 80 measuring points for each level and thus altogether 2000 measured values (5 models x 5 levels x 200 points). RESULTS: The described demonstrator showed itself suitable for the close-to-application attempts to the surgical accuracy. The maximum deviation A (max) indicated position of the Shaver from the reference value amounted to 1,93 mm. The maximum average value of the exceeding of a planned cavity amounts to 1,62 mm. CONCLUSIONS: Based on these results a virtual safety passage of 2.00 mm is sufficient. The study refers the clinical serviceability of the navigate-controlled Shaver in paranasal sinus surgery.

Equipment Design↗
PubMed2006

[Three-dimensional visualization of CT of the neck for surgical planning].

BACKGROUND: Surgical planning in ENT profits from computer assisted preoperative visualization and planning. The informative capability is to be improved by three-dimensional illustrating of the preoperative available data. The possibility of a 3-D-visualization of lymph nodes stands in the center of the interest. METHODS: 16 CT data sets with a tumor-classification of T1N1 or higher were included. Altogether 720 pseudo-3-D-illustrations were provided with an average of 9.3 objects. Current algorithms were used for the segmentation and visualization and the results were divided in three classes. RESULTS: The average time requirement for visualization and segmenting amounted to 122 minutes, the minimum value is at 61 minutes per data set. Automatic segmenting succeeded only with structures with clear grey tone differences to the environment. In all other cases an additional manual interaction had to take place. CONCLUSIONS: 3-D-Visualising of CT of the neck represents a new quality in preoperative planning. A clear trend at increasing detail loyalty and information efficiency showed up in the groups of B and C. It is possible to make from these pictures a quantitative statement on surgery relevant infiltration. Likewise conceivable are the postoperative quality control or planning and process control of a postoperative radio-chemotherapy. The automatic algorithms can be estimated as reliable. Application is still far from a clinically efficient use. With the rising efficiency of the computing systems, the improved software and the imaging systems the problems mentioned are, however, solvable.

Algorithms↗
PubMed2006

[Vocal efficiency parameters in children and adolescents: effect of physical development and singing activity].

The influence of physical development and singing activity on vocal efficiency in children and adolescents is well known from clinical experience. There is, however, no comparative study between singing and non-singing children which also considers the influence of age and gender. Therefore, standard values for evaluation in clinical practice are missing. We examined the following parameters in 164 healthy children and adolescents (90 boys, 74 girls; 11-16 years), 86 without singing activity (group A) and 78 members of children's and youth choirs (group B): frequency and dynamic range of voice and its borders with a voice range profile, mean fundamental frequency (normal and loud phonation), maximum voice intensity, and maximum duration of intonation. The statistical analysis was performed using three-way ANOVA. We found significantly higher ranges of frequency and intensity in singing children and adolescents (p<0.0001). The borders of the dynamic range and the upper border of the frequency range were significantly higher in group B (p<0.0001). The boys in group B used a higher mean fundamental frequency during loud phonation. There were no significant differences between groups in maximum voice intensity (p=0.051) but a tendency towards higher values in singing children. As an unexpected result, we found significantly higher values in maximum duration of intonation in group A (p<0.0001) independent of age and gender, which seems to be related to the methods used. Regular training of the singing voice results in positive effects on several voice parameters in children as well as adolescents. Our results can be used for estimating standard values in professional clinical and educational care of young singing voices and non-singing children. For this purpose, voice range profile is particularly suitable.

Adolescent↗
PubMed2006

[Accuracy and precision in the evaluation of computer assisted surgical systems. A definition].

Accuracy represents the outstanding criterion for navigation systems. Surgeons have noticed a great discrepancy between the values from the literature and system specifications on one hand, and intraoperative accuracy on the other. A unitary understanding for the term accuracy does not exist in clinical practice. Furthermore, an incorrect equality for the terms precision and accuracy can be found in the literature. On top of this, clinical accuracy differs from mechanical (technical) accuracy. From a clinical point of view, we had to deal with remarkably many different terms all describing accuracy. This study has the goals of: 1. Defining "accuracy" and related terms, 2. Differentiating between "precision" and "accuracy", 3. Deriving the term "surgical accuracy", 4. Recommending use of the the term "surgical accuracy" for a navigation system. To a great extent, definitions were applied from the International Standardisation Organisation-ISO and the norm from the Deutsches Institut für Normung e.V.-DIN (the German Institute for Standardization). For defining surgical accuracy, the terms reference value, expectation, accuracy and precision are of major interest. Surgical accuracy should indicate the maximum values for the deviation between test results and the reference value (true value) A(max), and additionally indicate precision P(surg). As a basis for measurements, a standardized technical model was used. Coordinates of the model were acquired by CT. To determine statistically and reality relevant results for head surgery, 50 measurements with an accuracy of 50, 75, 100 and 150 mm from the centre of the registration geometry are adequate. In the future, we recommend labeling the system's overall performance with the following specifications: maximum accuracy deviation A(max), precision P and information on the measurement method. This could be displayed on a seal of quality.

Equipment Failure Analysis↗
PubMed2006

[Workflow analysis to assess the efficiency of intraoperative technology using the example of functional endoscopic sinus surgery].

Evaluation of the efficiency of surgical technology systems has to date been largely subjective. The aim of this study was to develop an ontology for surgical procedures usable workflow structures, and the evaluation of surgical workflow analysis using the example of functional endoscopic sinus surgery (FESS). A total of 38 procedures (20 patients) were included. Surgery was carried out by seven different surgeons with different degrees of training. Description of the surgical procedures and resources is based on the standard EN1828/2001 (Structure for Classification and Coding Systems for Surgical Procedures). In addition the requirements of the Workflow Reference Models (document no. Tc00-1003), Workflow Management Coalition (WfMC) were integrated. The workflow recorded the position, frequency of change of position, use time, cleaning time and concept based instrument changes. A total of 293 items were used to define FESS. A total of 1,029 different endoscopic positions were documented. These could be combined into five major endoscopic positions. The frequency of position changes was 27.1 per side, the period spent in an endoscopic position is about 1.31 min. Time for the concept-caused instrument changing was 6.44 min per side. This study demonstrates the need for assistance in guiding the endoscope in FESS. Using the workflow-data, the concept of an assistant system is possible. We offer a basis for discussion of the development of an ontology, recording and analysing surgical workflows and their practical application.

Biotechnology↗
PubMed2006

[Clinical efficiency and the influence of human factors on ear, nose, and throat navigation systems].

BACKGROUND: The aim of this study was to evaluate the Navibase navigation system for ear, nose, and throat (ENT) surgery. A new methodology for evaluating surgical and human factors is developed. PATIENTS AND METHODS: The evaluation is based on 102 ENT surgical applications, including 89 cases of functional endoscopic sinus surgery (FESS). The evaluation of surgical and human factors was performed by seven ENT surgeons. To evaluate surgical performance, level of quality (LOQ) in the 89 cases of FESS was determined, comparing the surgeon's own impressions with those of the navigation system on a scale from 0 to 100 and further comparing them with clinical results. Intraoperative changes in surgical strategy were documented. The human factors of total confidence (trust), situation awareness, skill set requirement and workload shift were recorded as level of reliance (LOR). RESULTS: The maximum deviation amounted to 1.93 mm. Averaging the quality of information resulted in an LOQ of 63.59. Every second application of the navigation system (47.9%) led to a change in surgical strategy. Total confidence showed a positive evaluation of 3.35 points in LOR. CONCLUSION: Application-relevant information relevant to the application beyond only technical details permits comparison with other assisting systems.

Attitude of Health Personnel↗
PubMed2006

[Monitoring and conditioning in plastic and reconstructive ENT-surgery].

Plastic and reconstructive ENT surgery serves for reconstruction of form and function. Frequent indications in ENT surgery are the covering of large tissue defects after tumor operations, firing and/or explosion injuries, accidents, burns or massive infections. A high revision rate of up to 20 % in selective patient groups show that more knowledge of both monitoring and ischemia-/reperfusion mechanisms is necessary. Besides improved monitor proceedings biochemical cell procedures in pedicled and free flaps are getting more focused. In the last years certain physical and medical factors appear, which have influence on the long-term surviving of a pedicled or free flap, e. g. pre- and/or postconditioning. The increasing knowledge of changes in perfusion and oxygenation, which prevail in the flap, as well as different options of physical and pharmacological therapies permit a promising view into the future, in order to achieve an improved surviving of a pedicled or free flap in combination with improved monitor proceedings.

Diagnostic Imaging↗
PubMed2006

Establishing navigated control in head surgery.

Navigated Control (NC) describes an additional control for a tracked power driven instrument within a preoperatively segmented work space. In head surgery the authors first implemented NC in functional endoscopic sinus surgery (FESS). Recently the feasibility of NC for surgery on the petrosal bone is evaluated. NC in FESS and in petrosal bone surgery may reduce the risk of comorbidity and the time effort compared to the conventional surgical interventions.

Endoscopy↗
PubMed2005

[Intraoperative endosonographic guided resection of tongue carcinoma].

BACKGROUND: Exact estimation of a tumor's size and the definition of adequate resection margins in carcinomas of the tongue are often difficult because of the tumor's extension and deep infiltration. METHODS: We have developed a method that allows intraoperative visualisation and marking of tumor margins. Intra-operative endosonography was performed on nine patients with carcinomas of the tongue using a 8-12 MHz linear array transducer. The oral cavity was flooded with normal saline solution and the transducer was immersed therein. This allowed scanning in a non-contact mode. The tumor margins were marked with a surgical suture under endosonographic monitoring. RESULTS: In the nine patients studied, the histological margins corresponded to the sonographic margins. The sonographic marking proved to be useful during the resection of the tumor and histological safety margins were respected in each case. CONCLUSIONS: This non-invasive procedure provides a quick and reliable orientation during the resection of tongue carcinoma, and a more precise and individual definition of resection margins is possible. Intraoperative non-contact use of endosonography is a promising method.

Adult↗
PubMed2005

[Mechatronic in functional endoscopic sinus surgery. First experiences with the daVinci Telemanipulatory System].

BACKGROUND: This study examines the advantages and disadvantages of a commercial telemanipulator system (daVinci, Intuitive Surgical, USA) with computer-guided instruments in functional endoscopic sinus surgery (FESS). METHODS: We performed five different surgical FESS steps on 14 anatomical preparation and compared them with conventional FESS. A total of 140 procedures were examined taking into account the following parameters: degrees of freedom (DOF), duration , learning curve, force feedback, human-machine-interface. RESULTS: Telemanipulatory instruments have more DOF available then conventional instrumentation in FESS. The average time consumed by configuration of the telemanipulator is around 9+/-2 min. Missing force feedback is evaluated mainly as a disadvantage of the telemanipulator. Scaling was evaluated as helpful. The ergonomic concept seems to be better than the conventional solution. DISCUSSION: Computer guided instruments showed better results for the available DOF of the instruments. The human-machine-interface is more adaptable and variable then in conventional instrumentation. Motion scaling and indexing are characteristics of the telemanipulator concept which are helpful for FESS in our study.

Clinical Competence↗
PubMed2005

[Virtual training in head- and neurosurgery].

BACKGROUND: Surgical skill requires training at close-to-reality scenarios. Conventional procedures (practical exercises, anatomical or animal cadavers) are increasingly in conflict with objective parameters (costs of OR, quality management, cadavers availability and cost). Surgical procedures can be covered by using Virtual Surgical Reality (VSR). METHODS: We examined the principle of a VSR system and evaluated the results with 30 probands by the example of modified radical mastoidectomy and ventriculocisternostomy. Probands were divided in experienced (A) and non-experienced surgeons (B). The protocol included time of surgery, collisions and fatal injuries at altogether 15 passages (10 passages - break of 14 days - 5 passages). Additionally the Medical Level of Trust (LOT) describes the confidence into the surgical scenario and thus the quality by volume illustration, texture and haptic data feedback to the user. We used a numeric scale between 0 and 100 and the starting point of 50. RESULTS: The learning effect can be confirmed for both virtual scenarios. The mastoid scenario reaches a total confidence index LOT of 75. The ventricle scenario is evaluated with a total confidence index of 84. The necessary time for the opening of the antrum is reduced from 15.0 minutes (group A) and 22.5 minutes (group B) around 37 % to 9, 5 (group A) and around 56 % to 10.0 minutes (group B). The virtual haptic result was evaluated positive in both scenarios. CONCLUSIONS: VSR systems have the potential to revolutionize surgical training. All surgical experienced probands evaluated the VSR-scenario as near-to-reality. "Suspension of Disbelief" is the major condition for effective virtual reality training systems.

Clinical Competence↗