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Biomedical subjects

B F Tomandl

Publications and source records attributed to B F Tomandl.

16 recordsLinked to original sources
PubMed2006

Bone-subtraction CT angiography for the evaluation of intracranial aneurysms.

PURPOSE: CT angiography (CTA) has been established for detection and therapy planning of intracranial aneurysms. The analysis of aneurysms at the level of the skull base, however, remains difficult because bone prevents a free view. We report initial clinical results of an approach for automatic bone elimination from CTA data. MATERIAL AND METHODS: Before the bone-removal process 2 datasets are acquired: nonenhanced spiral CT with reduced dose and contrast-enhanced CTA. The software automatically registers the nonenhanced data onto the CTA data and selectively removes bone. Vascular structures, as well as brain tissue, remain visible. In this study, we investigated 27 patients with 29 aneurysms, 13 of which were located at the skull base. 3D volume-rendered images with and without bone removal were reviewed and compared with digital subtraction angiography by 2 radiologists in consensus. RESULTS: All supraclinoidal aneurysms were detected on 3D volume-rendered images of both CTA and bone-subtraction CT angiography (BSCTA). Four intracavernous and 3 paraclinoid aneurysms of the internal carotid artery were not visible or were only partially visible on conventional 3D CTA, whereas they could be optimally visualized with BSCTA. Bone removal was successful in all patients; the average additional time for postprocessing was 6.2 minutes. In 7 patients (26%), perfect bone removal without any artifacts was achieved. In most patients, some bone remnants were still present, though it did not disturb the 3D visualization of vascular structures. CONCLUSION: BSCTA allows robust and fast selective elimination of bony structures, thus ascertaining a better analysis of arteries at the level of the skull base. This is useful for both detection and therapy planning of intracranial aneurysms.

Angiography, Digital Subtraction↗
PubMed2005

Clinical evaluation of bone-subtraction CT angiography (BSCTA) in head and neck imaging.

Fifty-one patients were examined with bone subtraction CT angiography (BSCTA). Data were acquired on 4-and 64-slice spiral CT systems. The post-processing method is based on fully automatic registration of non-enhanced and contrast-enhanced CT data and subsequent selective bone removal. Vascular structures and brain tissue are retained with the original CTA noise level. Image quality and delineation of the pathologic process were assessed and artifacts introduced by the bone removal process recorded. The bone subtraction algorithm worked successfully in all examinations. The processing time was 6 min on average. Image quality was rated excellent in 20 (39%), good in 26 (51%) and acceptable in 5 (10%) patients. Ophthalmic arteries were visible in 12 (24%) patients bilaterally, in 13 (25%) patients unilaterally and in 26 (51%) patients at least at the origin. BSCTA improved visualization of the infraclinoid ICA and the vertebral arteries. The depiction of stenosis of the extracranial ICA and supraclinoid aneurysms was not significantly improved. In patients with suspicion of sinus thrombosis, BSCTA and conventional CTA yielded similar results. To conclude, BSCTA improves the visualization of vessels with close contact to bone and can improve the diagnostic accuracy and therapy planning of infraclinoid aneurysms.

Adult↗
PubMed2004

Bilateral orbital tumour as the presentation of mammographically occult breast cancer.

We report a rare case of bilateral orbital metastases as the presentation in a 63-year-old woman. Biopsy of a diffusely infiltrated medial rectus muscle suggested metastatic adenocarcinoma. Investigation revealed a palpable mass of the right breast not shown on mammography or sonography. Invasive lobular carcinoma was found at core-needle biopsy with histological features identical to those of the orbital lesion. Metastases to the extraocular muscles are uncommon, particularly as the initial abnormality in the absence of disseminated disease.

Breast Neoplasms↗
PubMed2004

[Multimodal computed tomography in acute cerebral infarction. Experience with a standardized protocol in 100 patients].

Computed tomography (CT) is the standard method of brain imaging in acute stroke. To an experienced examiner, nonenhanced CT will exclude hemorrhage and may indicate early ischemic signs. Reliable description of an ischemic area and the underlying vascular disease is not possible in the acute phase but is possible, particularly within the first hours, when therapeutic decisions on matters such as systemic thrombolysis are to be made. For such rapid decision-making, imaging must provide more information. Novel, contrast-enhanced CT techniques can provide this information. Perfusion CT (CTP) can show brain perfusion, allowing one to distinguish between reversible and irreversible damage in an ischemic area. Also, CT angiography (CTA) can detect occlusion or stenosis in the relevant vasculature. Using a modern, multislice CT scanner, it is now possible to combine these modalities of imaging. In a fast protocol for emergency evaluation, all three methods can be performed and evaluated to provide the crucial information within 15 min. In the first 102 patients examined within 6 h of symptom onset using this protocol, multimodal CT contributed substantially to therapeutic decisions, even though there are some limitations in these methods.

Acute Disease↗
PubMed2003

Clinical applications of 1H-MR spectroscopy in the evaluation of epilepsies--what do pathological spectra stand for with regard to current results and what answers do they give to common clinical questions concerning the treatment of epilepsies?

Nuclear magnetic resonance spectroscopy (1H-MRS) is a non-invasive method in detecting abnormal spectra of various brain metabolites containing N-acetylaspartate (NAA), Choline (Cho), Creatine (Cr), gamma-Aminobutyric acid (GABA) and Glutamate. Technical processing of the MR-systems, improved automated shimming methods and further development of special shim coils increase the magnetic field homogeneity and lead to a better spectral quality and spectral resolution. The handling of the systems becomes more user-friendly and is more likely to be used in routine diagnostics. The 1H-MRS has become a diagnostic tool for assessing a number of diseases of the central nervous system mainly including epilepsies and brain tumours. The role of 1H-MRS in the assessment of epilepsies will probably increase in future. In the following article, the principles of 1H-MRS and an overview of it in the evaluation and treatment of epilepsies with special regard to temporal lobe epilepsies (TLE) has been illustrated.

Brain↗
PubMed2002

Simultaneous involvement of third and sixth cranial nerve in a patient with Lyme disease.

We report a 57-year-old woman with neuroborreliosis presenting with headache, shoulder muscle pain and double vision. MRI demonstrated enhancement of the right third and sixth cranial nerves. A 3D MP-RAGE sequence was used to perform multiplanar reformations to show this more graphically. The patient was free of symptoms 1 month after completion of therapy, when thickening and contrast enhancement of the nerves were less pronounced.

Abducens Nerve Diseases↗
PubMed2001

[Rapid interactive 3-D imaging of the temporal bone with "direct volume rendering"].

INTRODUCTION: For the first time, the relatively new method of interactive direct volume rendering (dVR) allows for a fast and direct three-dimensional visualization of spiral CT data without any manual, explicit segmentation. This study was performed to prove whether dVR is capable of providing a meaningful three-dimensional visualization of the structures within the temporal bone. PATIENTS AND METHODS: In ten patients a three-dimensional visualization of the structures of the inner and middle ear was performed from spiral CT data on a commercially available graphics workstation. RESULTS: The cochlea and semicircular canals were visualized in good quality in all patients. The ossicles and bony facial canal were visualized in good or fair quality in most cases. The time needed for the visualization of the data and all target structures was less than 15 min in all cases. CONCLUSIONS: Three-dimensional visualization of the structures within the temporal bone from high-resolution spiral CT data using dVR is easily performed in a very short time on standard graphics workstations. This allows integrating three-dimensional visualizations into routine clinical work.

Computer Graphics↗
PubMed2001

[Diagnostic imaging in refractory temporal lobe epilepsy. A comparison of MR volumetry and multivoxel-MR-spectroscopy for assessment of postoperative prognosis].

While the importance of magnetic resonance (MR) spectroscopy, volumetry, and T2-relaxometry for preoperative localization has already been verified, the question arises as to what extent the individual techniques are useful for assessing postoperative prognosis with respect to seizures and neuropsychological outcome. In a prospective comparative study, 26 patients were examined preoperatively with a 1.5 T whole-body scanner. The MR spectroscopy was taken by high resolution 1 H proton spectroscopy, the volumetry with MP rage technique. The postoperative outcome was laid down using Engel's classification. Our results show that the metabolic changes can be divided into three groups using MR spectroscopy: unilateral, slightly bilateral, and severely bilateral to contralateral. In case of bilateral changes, the severity of metabolic changes in the nonoperated, contralateral side was decisive for postoperative outcome. The results from volumetry did not correlate with postoperative outcome.

Adult↗
PubMed1997

MR cisternography: a new method for the diagnosis of CSF fistulae.

The aim of this study was to compare a new MRI method for detecting the existence of cerebrospinal fluid (CSF) fistulae, i. e. MR cisternography, with CT cisternography. In a prospective study, 30 patients with post-traumatic CSF fistulae were examined. The MR examinations were performed with a 1.0-T whole-body MR system, using two T2(*)-weighted sequences, a 3D PSIF (time-inversed fast imaging with steady-state precession, FISP) and a 3D constructive interference steady-state (CISS) sequence. The results of MRI and CT cisternography were compared with the surgical findings. The sensitivity in detecting CSF fistulae with MR cisternography (PSIF: 89.9 %; CISS: 93.6 %) was higher than with CT cisternography (72.3 %). The sensitivity of CT cisternography at detecting CSF fistulae in patients with a size of dural lesion less than 2 mm or in patients with multiple dural lesions is significantly lower compared with the MR method. Although the localization of CSF fistulae always proved possible with MR cisternography, this could only be accomplished wih CT in 70 % of cases. The MR cisternography technique is a new examination method with a higher sensitivity for the detection of CSF fistulae than CT cisternography. The CISS technique is superior compared with PSIF and should be used in patients with high-flow CSF fistulas.

Adolescent↗
PubMedDate not supplied

The significance of bilateral CSI changes for the postoperative outcome in temporal lobe epilepsy.

PURPOSE: In a prospective study, we evaluated the significance of preoperative bilateral chemical shift spectroscopy imaging (CSI) changes for the prognosis of postoperative seizure outcome in the surgical treatment of patients with temporal lobe epilepsy (TLE). METHOD: CSI using multivoxel spectroscopy was performed. Twenty-six consecutive TLE patients scheduled for epilepsy surgery were included. To evaluate the value of the CSI with respect to postoperative seizure outcome, discriminant analysis with ipsilateral and contralateral CSI was performed. RESULTS: The discriminant analysis showed that the contralateral metabolic changes alone are able to predict seizure outcome whereby 92.3% of cases were correctly classified. Upon comparison of the two groups of seizure-free and non-seizure-free patients with respect to contralateral metabolic changes, the difference proved to be highly significant (paired t test: t = -6.3, df = 24, p < 0.001). CONCLUSION: Bilateral metabolic CSI changes have a predictive value for the postoperative outcome in patients with TLE. In patients with severe bilateral metabolic changes, poor seizure outcome is a likely result.

Adolescent↗
PubMedDate not supplied

Virtual labyrinthoscopy: visualization of the inner ear with interactive direct volume rendering.

Computed tomography (CT) is the modality of choice for detailed imaging of the bony labyrinth. Usually, information about the complex three-dimensional anatomic structures of the inner ear is presented as two-dimensional section images. Interactive direct volume rendering is a powerful method for visualization of the labyrinth. Unlike other visualization methods, direct volume rendering enables direct visualization of the bony labyrinth without explicit segmentation prior to the visualization process. Direct volume rendering was applied to visualization of the structures of the temporal bone in five patients without pathologic conditions and four patients with pathologic conditions. In all cases, clear representations of the bony labyrinth and the facial canal were provided. Because standard CT examinations combined with interactive visualization based on direct volume rendering are used, the method is fast and flexible. Therefore, this approach is applicable in routine clinical work. Problems occur in patients with effusion in the temporal bone because adjustment of imaging parameters for proper delineation of the target structures is difficult in this situation. However, direct volume rendering can produce meaningful images of high quality even in these problematic cases. The term virtual labyrinthoscopy is suggested for visualization of the labyrinth by using direct volume rendering.

Cochlea↗
PubMedDate not supplied

Local and remote visualization techniques for interactive direct volume rendering in neuroradiology.

The increasing capabilities of magnetic resonance (MR) imaging and multisection spiral computed tomography (CT) to acquire volumetric data with near-isotropic voxels make three-dimensional (3D) postprocessing a necessity, especially in studies of complex structures like intracranial vessels. Since most modern CT and MR imagers provide limited postprocessing capabilities, 3D visualization with interactive direct volume rendering requires expensive graphics workstations that are not available at many institutions. An approach has been developed that combines fast visualization on a low-cost PC system with high-quality visualization on a high-end graphics workstation that is directly accessed and remotely controlled from the PC environment via the Internet by using a Java client. For comparison of quality, both techniques were applied to several neuroradiologic studies: visualization of structures related to the inner ear, intracranial aneurysms, and the brainstem and surrounding neurovascular structures. The results of pure PC-based visualization were comparable with those of many commercially available volume-rendering systems. In addition, the high-end graphics workstation with 3D texture-mapping capabilities provides visualization results of the highest quality. Combining local and remote 3D visualization allows even small radiologic institutions to achieve low-cost but high-quality 3D visualization of volumetric data.

Brain Diseases↗