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Hans-Christian Bauknecht

Publications and source records attributed to Hans-Christian Bauknecht.

4 recordsLinked to original sources
PubMed2006

Behavior of metal implants used in ENT surgery in 7 Tesla magnetic resonance imaging.

Magnetic resonance imaging (MRI) has become increasingly important as an imaging technique in cross-sectional imaging of head and neck diseases. To investigate whether MRI examinations can be performed without risk in patients with metal implants even at higher field strengths, we examined different materials in 7 Tesla MRI. Implants near sensory organs like the middle ear or eye are of particular interest here. Using the 7 Tesla research MRI for small animals, we tested implants made of various metals like titanium, gold, gold/platinum, platinum/iridium, gold-plated silver, PTFE and stainless steel for heating, translocation and rotation according to a standardized protocol. A fiber optic temperature probe measured the heating of the implant before, during and after MRI scanning. None of the implants showed significant heating. The gold-plated stainless steel ventilation tube was the only implant to markedly change its position already in the Petri dish. Of the remaining implants, a trachea support ring, a nose dilatator and the wire from the ventilation tubes moved during vibration of the Petri dish. With exception of two implants, all implants changed positions in the water bath. In the swim test, the gold implants showed the least movement of all the implants. In this study, the properties of the non-ferromagnetic implant materials differed in the 7 Tesla MRI. Stainless steel ventilation tubes, the trachea support ring and the nose dilatator were not suited for the 7 Tesla MRI system, because they changed their position during MRI. In the case of ventilation tubes with a steel wire, the wire should be removed before MRI to prevent injury to the external auditory canal. There was a tendency for the pure gold implants to move less in the 7 Tesla MRI than all other tested materials. General statements cannot be made about the MRI suitability of different implants. Every implant should be individually examined to confirm its definitive MRI compatibility. Particularly, middle ear implants warrant special attention here due to their closeness to the oval window.

Equipment Failure Analysis↗
PubMed2002

Multislice computed tomographic imaging in temporal bone dysplasia.

OBJECTIVES: To evaluate the impact of multislice computed tomographic (MSCT) imaging, a recently developed computed tomographic technique, on imaging of temporal bone malformations. STUDY DESIGN: Retrospective case review. SETTING: The study was performed at a tertiary referral center. PATIENTS: High-resolution temporal bone studies of 168 consecutive patients were reviewed for various temporal bone malformations. MAIN OUTCOME MEASURES: Visualization of various dysplastic conditions of the temporal bone without the need for supplementary scan procedures or additional imaging techniques. INTERVENTION: MSCT imaging was performed on a scanner with four detector rows by using the following parameters: 120 kV, 50 mA/s, 0.5-mm slice thickness, 0.2-mm reconstruction increment, pitch factor of 0.75, and a field of view of 160 mm. Two-dimensional and three-dimensional image reconstructions were performed subsequent to data transfer to a workstation. In one patient suspected of having a vascular dysplasia, high-resolution MSCT imaging was supplemented by multislice computed tomographic angiography. RESULTS Temporal bone dysplasias were encountered in 28 patients (16.7%), affecting the external auditory canal (n = 15), the middle ear (n = 18), the inner ear (n = 5), and the vascular system (n = 3). All temporal bone dysplasias were visualized by two-dimensional and three-dimensional images of excellent detail resolution. In none of the patients were supplementary computed tomographic scans necessary, except for one patient with evidence of an aberrant course of the internal carotid artery. Multislice computed tomographic angiography obviated the need for invasive diagnostic procedures. CONCLUSION: MSCT imaging of the temporal bone allows for comprehensively assessing various dysplasias through high-quality two-dimensional and three-dimensional image reconstructions.

Adolescent↗
PubMedDate not supplied

Effect of 7.0 Tesla MRI on upper eyelid implants.

To ensure the MRI compatibility of various eyelid implants in high-field MRI, 3 eyelid weights made of pure gold (99.99%), pure platinum (99.95%), and a platinum (97%)/iridium (3%) alloy were examined in vitro. Temperature changes, position changes, and imaging artifacts of the different implants were determined in a small-bore 7.0 Tesla MRI system. The 7.0 Tesla MRI system demonstrated that none of the eyelid implants carried a risk of heating or dislocation; therefore, these implants are MRI compatible up to a magnetic field strength of 7.0 Tesla.

Alloys↗