PubMed Health⌕ Search

Biomedical subjects

Joachim Mühling

Publications and source records attributed to Joachim Mühling.

At least 19 recordsLinked to original sources
PubMed2006

Diagnostic imaging in the management of craniosynostoses.

Craniosynostoses are the most frequent craniofacial malformations. However, with a prevalence of 3-6 cases per 10,000 live births they are amongst the rarely seen diseases and their definite diagnosis thus poses a challenge to the physician. When an abnormal calvarial configuration is detected, a radiological evaluation is necessary to characterize the deformity and to guide the corrective surgical procedure. The demand for clear diagnostic criteria is justified by the severity of the disease and the possible consequences of delayed diagnosis. In addition to the clinical signs (deformation of the head), conventional skull X-rays show typical radiological alterations and are used for basic diagnostics. Diagnostic tests that may be performed to confirm the diagnosis and assess the extent of the problem, include computed tomography (CT), 3D-CT, magnetic resonance imaging (MRI) scans, and ultrasonography. In the present review we will describe the most important clinical and radiological characteristics of craniosynostosis by means of clinical, radiological and operative situs examples.

Craniosynostoses↗
PubMed2006

Recurrent FGFR1 amplification and high FGFR1 protein expression in oral squamous cell carcinoma (OSCC).

Chromosomal aberrations are known to have an impact on the initiation and progression of oral squamous cell carcinoma (OSCC), but individual genes involved in OSCC pathogenesis are poorly described. To elucidate the molecular events underlying oral carcinogenesis, a set of primary OSCC were screened for distinct genetic imbalances by means of array-based comparative genomic hybridisation. For this, a DNA array was used containing 812 genomic targets including oncogenes, tumour-suppressor genes and chromosomal regions frequently altered in human neoplasms. The most frequent aberrations were amplification of MYC, EGFR, CCND1 and PIK3CA, whereas deletions affected TRAILR1 and ATM. Furthermore, a distinct high-level amplification of the fibroblast growth factor receptor 1 (FGFR1) locus was detected in two cases. Detailed FISH analysis on OSCC tissue microarray sections revealed amplification prevalence for FGFR1 of 17.4% (16/92). Furthermore, FGFR1 protein analysis by immunohistochemistry on a TMA containing 178 OSCC found a high FGFR1 expression in tumours of early t-stadium and UICC stage (T1/2 vs. T3/4: p=0.002; SI-II vs. S III-IV: p=0.048). Our results indicate that an increase in FGFR1 expression contributes to oral carcinogenesis at an early stage of development.

Carcinoma, Squamous Cell↗
PubMed2006

The influence of computed tomography motion artifacts on computer-assisted surgery.

PURPOSE: Motion artifacts can significantly deteriorate the precision of a computer-assisted surgical intervention because they destroy the isometric representation of tomographic pictures. In the context of a study, the influence of typical motion artifacts on the precision of markerless laser registration in image-guided oral and maxillofacial surgery was analyzed, and quality factors for evaluation of the isometry of a computed tomography (CT) dataset were determined. PATIENTS AND METHODS: Twenty patients underwent markerless registration, the precision being determined by means of intraoral evaluation markers. Then the 20 CT datasets were used for simulation of a typical motion artifact. The precision of the overlay of the dataset was checked again on the navigation workstation, in absence of the patient. The navigation system used was the Surgical Segment Navigator SSN++ (University of Heidelberg, Heidelberg, Germany). RESULTS: The motion artifacts reduced the average patient registration from 1 to 4 mm. Quality factors for the isometry of a CT dataset were: the volume enclosed between the soft tissue mantles of the preoperative CT dataset and the intraoperative laser scan dataset, as well as the orientation of the normal vectors on the 3-dimensional reconstruction of the CT dataset. CONCLUSION: The isometry of a CT dataset should always be checked before performance of a computer assisted surgical intervention because anisometric datasets result in inaccurate patient registration and navigation.

Artifacts↗
PubMed2005

Physiological shift of facial skin and its influence on the change in precision of computer-assisted surgery.

Methods of recording landmarks on the facial skin without the use of markers have become increasingly accepted in image-guided surgery. However, position or muscular activity may change the skin's geometry and generate a lack of agreement between the facial contours recorded before and those recorded during the operation. In the present study, we measured this physiological shift of facial skin and evaluated its influence on the accuracy of stereotactic recording. We made laser-scans of the skin of 20 conscious patients while they were sitting and lying, both at rest and when smiling. The laser-scans were referenced to the corresponding computed tomographic dataset, and the accuracy of the recording was calculated. Gravitational or muscular shifts of the skin reduced the mean (S.D.) accuracy of recording to 1.7 (0.3)mm. The loss of accuracy was significantly correlated with the dynamic and gravitational wrinkling of the facial skin and with the body mass index of each patient.

Adolescent↗
PubMed2005

Relationship between the risk of mandibular angle fractures and the status of incompletely erupted mandibular third molars.

BACKGROUND: Several studies have shown the increased risk of mandibular angle fractures associated with incompletely erupted mandibular third molars. But only a few reports analysed in detail the relationship of the status of eruption of this tooth and this type of fracture. OBJECTIVES: The purpose of this study was to clarify the influence of the eruption status of incompletely erupted mandibular third molars on the incidence of mandibular angle fractures. METHODS: Four hundred and thirty-six mandibular halves in 218 patients with mandibular fractures, aged between 15 and 40 years old, were analysed using panoramic radiographs. RESULTS: The incidence of angle fractures in the mandibular halves with incompletely erupted mandibular third molars was 30.8% and this was statistically significantly higher than that in another group (p<0.0001). Deeply located mandibular third molars clearly showed a higher incidence of this fracture when compared with the adjacent second molar (p<0.0001). CONCLUSION: The results of this investigation showed that incompletely erupted mandibular third molars close to the inferior border of the mandible have a high risk of angle fractures.

Adolescent↗
PubMed2005

Template-based registration for image-guided maxillofacial surgery.

PURPOSE: Fiducial marker registration using bone screws is a proved and tested method for patient-to-image registration for image-guided surgery of the head. The use of intraoral fiducial markers mounted on a template for the maxillary dentition is a less invasive alternative and is in use for intraoral image-guided surgery. The aim of this study was to verify if this method is sufficiently accurate for extraoral use. MATERIALS AND METHODS: Registration was performed using 243 different configurations of fiducial markers mounted on a maxillary template. The accuracy of the identification of artificial skull-mounted targets located in surgically relevant locations was determined for each registration. RESULTS: Targeting accuracy was sufficient for image-guided surgery of the maxilla, the midface, the orbit, and the pterygopalatine fossa. In the regions of the calvarium, however, average target registration error was > or =1.5 mm. Average target registration error was >3 mm. CONCLUSION: Fiducial marker registration based on a maxillary template is a safe and non-invasive alternative to bone-mounted fiducial markers for image-guided surgery in the regions of orbit, face, maxilla, and pterygopalatine fossa.

Bone Screws↗
PubMed2005

Differential KIT expression in histological subtypes of adenoid cystic carcinoma (ACC) of the salivary gland.

Adenoid cystic carcinoma (ACC) of the salivary gland is characterized by a prolonged but inevitably unfavorable clinical course. Recent studies suggested the transmembrane tyrosine kinase KIT to be involved in ACC pathogenesis. To investigate KIT expression in histologically defined subgroups of ACC and to clarify whether KIT gene copy number gain contributes to KIT overexpression, tumor tissue microarray sections including 55 ACC tumors were analyzed by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). The prevalence of positive KIT immunostaining was 89% (49/55). Strong immunostaining of KIT was only found in cribriform and tubular but never in solid subtypes (p=0.02). Average KIT staining intensity was higher in cribriform and tubular (n=37) compared to solid (n=18) ACC subtypes (p=0.005). FISH analysis revealed copy number gains of the KIT gene in 6.1% (3/49) of tumors analyzed. Our results implicate that specific KIT tyrosine kinase inhibitors such as imatinib, might be used in future therapeutic approaches against subgroups of ACC.

Carcinoma, Adenoid Cystic↗
PubMed2004

Advanced surface-recording techniques for computer-assisted oral and maxillofacial surgery.

Markerless recording of patients based on natural anatomical surfaces makes planning of computer-assisted surgery much easier, as it is not necessary to place and measure markers. Recording of the surgical site with a laser scan takes the place of conventional marker-based recording. We have used auricles as well as the maxilla and mandible as reproducible surfaces. The geometric congruence of the laser scanned surface with the corresponding surface in the computed tomographs data-set and the applied intraoperative accuracy after recording with a laser scanner have been evaluated, and the system was successful in the maxilla (mean precision: 0.8mm, standard deviation: 0.3mm). In the mandible, the tongue and mobile floor of the mouth led to geometric incongruence and inadequate laser scanning. An exact recording using auricles was possible only as long as the auricles had not been temporarily deformed by the head support during CT imaging.

Ear, External↗
PubMed2004

Markerless laser registration in image-guided oral and maxillofacial surgery.

PURPOSE: The use of registration markers in computer-assisted surgery is combined with high logistic costs and efforts. Markerless patient registration using laser scan surface registration techniques is a new challenging method. The present study was performed to evaluate the clinical accuracy in finding defined target points within the surgical site after markerless patient registration in image-guided oral and maxillofacial surgery. PATIENTS AND METHODS: Twenty consecutive patients with different cranial diseases were scheduled for computer-assisted surgery. Data set alignment between the surgical site and the computed tomography (CT) data set was performed by markerless laser scan surface registration of the patient's face. Intraoral rigidly attached registration markers were used as target points, which had to be detected by an infrared pointer. The Surgical Segment Navigator SSN++ has been used for all procedures. SSN++ is an investigative product based on the SSN system that had previously been developed by the presenting authors with the support of Carl Zeiss (Oberkochen, Germany). SSN++ is connected to a Polaris infrared camera (Northern Digital, Waterloo, Ontario, Canada) and to a Minolta VI 900 3D digitizer (Tokyo, Japan) for high-resolution laser scanning. RESULTS: Minimal differences in shape between the laser scan surface and the surface generated from the CT data set could be detected. Nevertheless, high-resolution laser scan of the skin surface allows for a precise patient registration (mean deviation 1.1 mm, maximum deviation 1.8 mm). CONCLUSIONS: Radiation load, logistic costs, and efforts arising from the planning of computer-assisted surgery of the head can be reduced because native (markerless) CT data sets can be used for laser scan-based surface registration.

Data Display↗
PubMed2003

Digital tomosynthesis-experiences with a new imaging device for the dental field.

Based on the principles of classic film tomography, a new digital X-ray device for dental sites was developed and clinically evaluated. The tomosynthesis process produces several slices from a finite number of radiographs taken from different projection angles, obtaining a three-dimensional image of the jaws and teeth. During evaluation of an industrial prototype, a total of 52 tomosynthesis data sets were made covering different anatomic areas. Of those, 32 sets were assessed by ten radiologically experienced dentists. Anatomic regions not shown on conventional intraoral dental films were displayed due to the extraoral sensor. Diagnostic images of high value were mainly achieved within the scope of lateral views and transverse views in the frontal region. Even small structures such as the periodontal ligament could be shown in several planes, resulting in superposition-free representation. The elimination of metal artefacts caused by dental restorations was facilitated. However, improvements can be made in definition and resolution. Views in the sagittal plane and incomplete blurring of the contralateral jaw are difficulties that remain. The tomosynthesis process combined with a planned 3D representation is likely to be well suited for dental radiology. The use of such a device could be much less expensive than computed tomography (CT). Furthermore, it offers higher spatial resolution, exposes patients to less radiation, and could be easily used in daily practice, even chairside.

Adolescent↗
PubMed2003

Laser-scan-based navigation in cranio-maxillofacial surgery.

BACKGROUND: In computer-assisted surgery, a correlation between a volume data set and the surgical site is required in order to localize the patient's head on the operating table. Registration markers are commonly used for this procedure. However, the marker registration is associated with high logistics, since the markers have to be placed prior to data set acquisition and have to be kept in their position until the patient enters the operating room. This study deals with a new markerless registration method in cranio-maxillofacial surgery that is based on a high-resolution laser-scan of the patient's (relaxed) skin surface. PATIENTS: 20 patients with tumours, bone malformations or foreign bodies, scheduled for computer-assisted surgery, were involved in the study. STUDY DESIGN: The clinically applied accuracy of the laser-scan-based registration was measured through additionally placed registration markers. The inherent precision of the laser-scan registration system was controlled in phantom studies. RESULTS: The clinically applied accuracy of the new laser-scan-based registration technique ranged between 0.2 and 1.8 mm with a mean deviation of 1.1mm and a standard deviation of 0.3 mm. CONCLUSION: The facial skin surface can serve as a sufficiently stable and invariable reference base in order to register patients for computer-assisted cranio-maxillofacial surgery.

Algorithms↗
PubMed2003

Maxillofacial fractures resulting from falls.

OBJECTIVE: This study was performed to clarify the characteristics of facial fractures caused by falls with a particular focus on aetiology. PATIENTS: Of 505 patients with facial fractures treated in the Department of Oral and Maxillofacial/Craniofacial Surgery, Heidelberg University Hospital from January 1997 to May 2001, 129 patients injured by falls were analysed. STUDY DESIGN: Aetiological analysis was performed according to falling patterns. RESULTS: The distribution of age showed two peaks in the 4th and 8th decades, and the male to female ratio was 1.1:1, unlike the overall facial fracture ratio of 3:1. Seventy-six patients had fallen from standing height or less and 44 patients had fallen from greater heights. The former cases were more often seen in older females. More severe injuries tend to be seen in the patients who have fallen from greater heights, and in the cases associated with acute medical disorders. CONCLUSION: This retrospective study documents the higher risk of fractures in older females and the higher risk of severe injury in those patients who were unconscious. This is in agreement with recent orthopaedic studies.

Accidental Falls↗
PubMed2003

Soft tissue scanning for patient registration in image-guided surgery.

Prior to an image-guided surgical intervention, a correlation between the patient's data set and the surgical site is required. This study introduces a markerless registration method for cranio-maxillofacial surgery that is based on a high-resolution laser scan of the patient's skin surface. The Surgical Segment Navigator SSN++ rejects contaminated surface measurements in a way similar to the bluescreen technique. Acquisition of the spatial position and the corresponding surface color of each laser-scanned point facilitates this bluescreen method, removing points with a defined surface color, e.g., blue or green points. The accuracy of the laser-scan-based registration was measured via additional intraoral titanium-markers. These markers served only to check the accuracy of the markerless registration process. In twelve patients, the stability and accuracy of the data set alignment was evaluated for high-(300,000 surface points), medium-, and low-resolution (down to 3,750 surface points) laser scanning. The accuracy of the registration technique was best for high-resolution laser scanning (mean deviation 1.1 mm; maximum deviation 1.8 mm). Low-resolution laser scans revealed inaccuracies up to 6 mm.

Face↗
PubMed2003

Development and first patient trial of a surgical robot for complex trajectory milling.

OBJECTIVE: Today's surgical robots normally perform "simple" trajectories, e.g., assisting as tool-holding devices in neurosurgery, or milling linear paths for cavities in total hip replacement. From a clinical point of view, it is still a complex undertaking to implement robots in the operating room. Until now, robot systems have not been used in patient trials to mill "complex" trajectories, which involve many positional and orientation changes and are often necessary in cranio-maxillofacial (CMF) surgery. This paper presents the RobaCKa surgical robot system, which allows more precise execution of surgical interventions and milling of "complex" trajectories. MATERIALS AND METHODS: The main components of the RobaCKa system are a (former) CASPAR robot system, a POLARIS system, and a force-torque sensor. RESULTS: In the first patient trial (April 2003) the planned trajectory was executed with an error of 0.66 +/- 0.2 mm. CONCLUSIONS: The use of former industrial robots for surgical applications is possible but complex. The advantages are improved precision and quality and the possibility of documentation. The use of such systems is normally limited to research institutions or large clinics, because it is hardly possible to implement the necessary technical and logistic efforts in routine surgical work.

Craniotomy↗
PubMed2003

A VR-system supporting symmetry related cranio-maxillofacial surgery.

The reconstruction of patients with large deformations in the facial area should consider functional aspects as well as aesthetical ones. In this paper, an integrated virtual reality system which allows bone manipulation, osteotomy planning, calculation of implants for soft tissue and bones combined with the calculation of the post-operative appearance is presented. It is a valuable tool for a wide range of cranio-maxillofacial surgeries. Due to the generalized approach of the underlying algorithms, it is a basis for further clinical applications in other surgical fields.

Computer Simulation↗
PubMed2002

Volumetric implant-planning based on Symmetry Considerations.

Symmetry Considerations can be used not only to plan the desired shape of reconstructured bone structures, but also to generate prototypes for soft tissue implants. The poster describes a system which allows to calculate a symmetry plane in the facial area automatically and computes proposals for implants or transplants. The system presented has been used to calculate soft tissue implants and a replacement for parts of the lower jaw.

Cephalometry↗