Biomedical subjects

U Hubbe

Publications and source records attributed to U Hubbe.

5 recordsLinked to original sources

PubMed2005

Benefits and limitations of image guidance in the surgical treatment of intracranial dural arteriovenous fistulas.

BACKGROUND: Despite major advances in endovascular embolization techniques, microsurgical resection remains a reliable and effective treatment modality for dural arteriovenous fistulas (DAVF). However, intraoperative detection of these lesions and identification of feeding arteries and draining veins can be challenging. In a series of 6 patients who were not candidates for definitive treatment by endovascular embolization we evaluated the benefits and limitations of computer-assisted image guidance for surgical ablation of DAVF. METHODS: Of the 6 patients, 5 presented with haemorrhage and one with seizures. Diagnosis of DAVF was made by conventional angiography and dynamic contrast enhanced MR angiography (CE-MRA). All patients were surgically treated with the assistance of a 3D high resolution T1-weighted MR data set and time-of-flight MR angiography (MRA) obtained for neuronavigation. Registration was based on cranial fiducials and image-guided surgery was performed with the navigation system. FINDINGS: Four of the 6 patients suffered from DAVF draining into the superior sagittal sinus, one fistula drained into paracavernous veins adjacent to the superior petrosal sinus and one patient had a pial fistula draining in the straight sinus. DAVF diagnosed with conventional angiography could be located on CE-MRA and MRA prior to surgery. MRI and MRA images were combined on the neuronavigation workstation and DAVF were located intraoperatively by using a tracking device. In 4 out of 6 cases neuronavigation was used for direct intraoperative identification of DAVF. Brain shift prevented direct tracking of pathological vessels in the other 2 cases, where navigation could only be used to assist craniotomy. Microsurgical dissection and coagulation of the fistulas led to complete cure in all patients as confirmed by angiography. CONCLUSIONS: Neuronavigation may be used as an additional tool for microsurgical treatment of DAVF. However, in this small series of 6 cases, surgical procedures have not been substantially altered by the use of the neuronavigation system. Image guidance has been beneficial for the location of small, superficially located DAVF, whereas a navigated approach to deep-seated lesions was less accurate due to the familiar problem of brain shift and brain retraction during surgery.

Adult↗

PubMed2005

[LED autoregistration in navigated endonasal sinus surgery].

BACKGROUND: In endonasal sinus surgery, computer aided surgery (CAS) is a generally accepted method. Applying CAS, there are basic problems with the constancy of accuracy at a free mobile patient head as well as with extended referencing time. The navigation system manufacturer Stryker-Leibinger invented together with our working group a non-invasive, frameless, automatic patient registration and simultaneous tracking system for navigated endonasal sinus surgery. With this new user-friendly system it concerns an active, LED-based, self-adhesive on the surface of splanchnocranium autoregistration mask. MATERIAL AND METHOD: The LED autoregistration mask was tested in an anatomic cadaver study and an ongoing clinical patient study regarding manageability, applicability and accuracy. Accuracy measurements were accomplished on different control points of the head in the cadaver study. The determination of accuracy was calculated with the metric Euclidean distance. Further we report on our experiences with a total of 20 patients applying the new mask. To control the accuracy, anatomic landmarks of the patients were adducted. Goal of our study was to determine the accuracy of the LED mask and to compare it with titanium screw markers, the valid reference gold standard. RESULTS: The LED autoregistration mask convinced by a high precision with relatively simple useability. Total accuracy amounted to 2.22 +/- 0.91 mm. The LED system proved to be a valuable orientation guide mainly at revision surgeries with modified anatomy. CONCLUSIONS: LED surface autoregistration is especially suitable for endonasal sinus surgery and represents a very helpful tool for the rhinosurgeon. Our accuracy studies have shown that the LED autoregistration mask is comparable to the gold standard titanium screw markers and, in addition, very reliable.

Computer Graphics↗

PubMed2002

Error analysis in cranial neuronavigation.

Neuronavigation systems are now an important component of many modern neurosurgical treatment strategies. Their support facilities intraoperative orientation and makes neurosurgical operations more precise and less traumatic. Computer-aided neurosurgery is definitively not a temporary fashionable phenomenon, the concept of neuronavigation is here to stay. This report summarizes a ten-years-long experience and presents an error analysis of 108 failures (12.4 %) in a total of 874 image-guided cranial neurosurgical procedures with an arm-linked (mechanical) system and two different infrared-light emitting (optical) systems. The application of neuronavigation incurs multiple reasons for pitfalls because of the complex man-machine interface. Principally, we have to differentiate two types of errors: "machine made errors" due to soft- or hardware failure and "man made errors" generally, due to inadequate handling of the navigation system. The error analysis demonstrated that the so-called human interface plays the main role causing a high error rate.

Bias↗

PubMed1999

Radiological and histological findings in spinal intramedullary angiolipoma.

We report an intramedullary angiolipoma with spinal cord compression studied by MRI, angiography and CT. Angiolipomas of the spine are rare benign tumours containing vascular and mature adipose elements. They are epidural in more than 90 % of the cases; only three cases of intramedullary angiolipoma are described. The clinical picture is nonspecific, but MRI and CT suggest the diagnosis.

Adult↗

PubMedDate not supplied

The influence of gliomas and nonglial space-occupying lesions on blood-oxygen-level-dependent contrast enhancement.

BACKGROUND AND PURPOSE: Functional MR (fMR) imaging with blood-oxygen-level-dependent (BOLD) contrast enhancement is increasingly used as a noninvasive tool for presurgical mapping in patients with intracranial tumors. Most physiologic studies of task-related BOLD contrast enhancement have involved healthy volunteers. Therefore, it is not known whether BOLD contrast is evoked in the same way in or adjacent to tumor tissue. The purpose of this study was to study the influence of different intracranial tumors on BOLD contrast enhancement. METHODS: fMR mapping of the sensorimotor cortex was successfully performed in 15 of 21 patients with intracranial space-occupying lesions by using a bimanual motor task. Tumors were located either within the sensorimotor area itself or in adjacent brain areas, inducing changes of signal intensity on T2-weighted images along the pre- or postcentral gyrus. Space-occupying lesions were divided into a group comprising gliomas (seven cases) and a group comprising nonglial space-occupying lesions (three metastases, two cavernomas, one abscess, one arteriovenous malformation, one meningioma). A hemispheric activation index was calculated using the volume of activation on the affected and on the contralateral hemisphere. Hemispheric activation indices of gliomas and nonglial lesions were compared statistically. RESULTS: The activated volume in the hemispheres ipsilateral to the nonglial lesions was 14% larger than in the contralateral hemisphere, whereas in the hemispheres ipsilateral to gliomas, the activated volume decreased by 36% in comparison with the contralateral hemisphere. The difference between nonglial lesions and gliomas was significant (P < .05). CONCLUSION: The generation of BOLD contrast enhancement is reduced near gliomas but is not affected by nonglial tumors.

Brain Diseases↗