Biomedical subjects

Norbert Suhm

Publications and source records attributed to Norbert Suhm.

4 recordsLinked to original sources

PubMed2004

Modality-based navigation.

Modality-based navigation (MBN) means the interactive tracking of instruments in a co-ordinate system defined by an imaging modality, eg, CT, MR, or a fluoroscope. During the registration process, a transformation matrix between the two co-ordinate systems of the digitizer and imaging modality is calculated. Navigation can start immediately after collection of the images without an intraprocedural registration process. Since the imaging modality belongs to the OR or the intervention suite, image update can be performed at any time. Following a step-by-step procedure with navigation and image update in a reasonable sequence, the risk for a virtual-real mismatch is minimized. For CT-MBN, we obtained a freehand absolute positioning accuracy of 1.9+/-1.1 mm in vitro. The in vivo freehand absolute positioning accuracy in pelvic fracture fixation was determined to be 3.1 mm (unpublished data). From our point of view, modality-based navigation is an efficient and safe alternative tool for computer aided interventions.

Fluoroscopy↗

PubMed2004

Computer aided long bone fracture treatment.

Intraoperative fluoroscopy is the tool for intraoperative control of long bone fracture reduction and osteosynthesis. Limitations of this technology include: High radiation exposure to the patient and the surgical team, limited field of view, image distortion, limitation to 2-D representations, and cumbersome updating of verification images. Fluoroscopy based navigation systems partially address these limitations by allowing fluoroscopic images to be used for real-time surgical localization and instrument tracking. In a clinical study on computer guidance by virtual fluoroscopy for distal locking, the capability to provide online guidance with significantly reduced fluoroscopy times is demonstrated. Virtual fluoroscopy applied for guidewire placement in a laboratory setup demonstrated the potential of the method to reduce procedure times, and the potential to increase precision of implant placement with decreased fluoroscopy times. By using virtual reality enhancement, starting from multiple registered fluoroscopy images, a virtual 3-D cylinder model for each principal bone fragment is reconstructed. This spatial cylinder model is not only used to supply a 3-D image of the fracture, but also allows effective fragment projection extraction from the fluoroscopic images and further achieves radiation-free updates of in-situ surgical fluoroscopic images through a non-linear interpolation and warping algorithm. After primary image acquisition, the image intensifier was replaced by the virtual reality system. It was shown that all the steps of the procedure, including fracture reduction and LISS osteosynthesis can be performed completely in virtual reality.

Fluoroscopy↗

PubMed2004

The MEPUC concept adapts the C-arm fluoroscope to image-guided surgery.

Image-guided surgery requires surgeons to be able to manipulate the imaging modality themselves and without delay. Intraoperative fluoroscopic imaging does not meet this requirement as the C-arm fluoroscope cannot be operated or positioned by the surgeons themselves. The Motorized Exact Positioning Unit for C-arm (MEPUC) concept aims to optimize the workflow of positioning the C-arm fluoroscope. The hardware component of the MEPUC equips the fluoroscope with electric stepping motors. The software component allows the surgeon to control the fluoroscope's movements. The study presented here showed that translational movements within the x-y plane are most frequently performed when positioning the C-arm fluoroscope. Furthermore, reproducing a former projection was found to be a frequent task during image-guided procedures. In our opinion, the MEPUC concept adapts the fluoroscope to image-guided surgery. The most important improvement being definition of a bidirectional data exchange between the surgeon and the C-arm fluoroscope: positioning data from the surgeon to the C-arm fluoroscope and-subsequently-image information from C-arm fluoroscope to the surgeon.

Femoral Fractures↗

PubMed2004

Fluoroscopic guidance versus surgical navigation for distal locking of intramedullary implants. A prospective, controlled clinical study.

A prospective controlled clinical study was performed to compare fluoroscopic guidance with fluoroscopy-based surgical navigation for distal locking of intramedullary implants. Forty-two patients with fractures of the lower extremity treated by intramedullary nailing were divided in two groups: distal locking either with fluoroscopic guidance (group I) or with surgical navigation (group II). The average fluoroscopic time to insert one interlocking screw with fluoroscopic guidance was 108 s compared with 7.3s in the navigation group. The average procedure time to insert one interlocking screw in group I was 13.7 min compared with 17.9 min in group II. The drill bit failed to pass through the interlocking hole in one patient from group II. There was no significant difference in the technical reliability between both groups. Fluoroscopic times to achieve equivalent precision are reduced with fluoroscopy-based surgical navigation compared with fluoroscopic guidance. Fluoroscopy-based surgical navigation is recommended for intraoperative guidance in situations where reduction of exposure to radiation is considered advantageous over the increase of procedure time.

Female↗