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M Knauth

Publications and source records attributed to M Knauth.

60 records · Page 4Linked to original sources
PubMed1994

Preliminary experience with the Toronto SPV stentless porcine bioprosthesis for aortic valve replacement.

From November 1992 to March 1993 fourteen patients received the Toronto SPV stentless porcine xenograft as aortic valve replacement. Median age was 56 years (range 32-70 years). 7 patients were male and 7 female. Implanted valve sizes ranged from 23 mm to 29 mm, the majority of patients received valves with 27 and 29 mm tissue diameter. A learning process was evident by aortic crossclamp time decreasing with experience. No valve-related mortality or morbidity occurred. Postoperatively echocardiography showed near normal valve performance in most patients. The longevity of the valve, however, still has to be established. Meanwhile we continue the implant of stentless bioprostheses as aortic valve substitutes in selected patients.

Adult↗
PubMed1994

How does the stereotactic workstation help the neurosurgeon?

At the KUL University of Leuven a workstation for the planning of neurosurgical stereotactic procedures has been developed. Its benefits are illustrated in three exemplary cases. The CT and/or MR images, acquired under stereotactic conditions, are transmitted via a PACS network (picture archiving and communication systems) directly to the stereotactic workstation in the operating theater. Target and entry point can be accurately defined on zoomed images. The trajectory can be checked and modified on all registered data sets and on resliced images along any plane. Maximum intensity projection of magnetic resonance angiography data sets along any arbitrary direction show the relative position of the blood vessels and the trajectory. During the preceding 32 months 29 patients were operated on using the stereotactic workstation. Postoperatively no new neurological deficit was observed in any of these patients. The workstation improves patient safety and increases the accuracy of neurosurgical stereotactic operations, because it helps the neurosurgeon to avoid blood vessels and/or important functional areas.

Adult↗
PubMed1993

[Value of neuroradiologic procedures in preoperative assessment of cervical myelopathy].

The diagnostic value of computed tomography (CT), myelography, myelo-CT and magnetic resonance imaging (MRI) was retrospectively investigated in 94 patients in whom Cloward's operation had been performed due to symptoms of cervical myelopathy (CM). In 55 patients with "classical" cervical spondylotic myelopathy all investigated diagnostic procedures demonstrated a comparably high degree of sensitivity and specificity, thus proving comparable for diagnosing pathological alterations of the cervical spine. In 39 patients with CM as a consequence of an acute cervical disk prolapse, however, MRI was superior and offered the highest diagnostic accuracy. The following general diagnostic strategy in patients with CM can be suggested: Conventional plain film radiography of the cervical spine, axial CT of the involved segments and MRI of the cervical spine in sagittal and transversal orientation, using T1 and T2 weighted pulse sequences. The combined use of these techniques allows the exact evaluation of any relevant structure alterations of the cervical spine that determine differential therapeutic approaches.

Adult↗
PubMedDate not supplied

MR enhancement of brain lesions: increased contrast dose compared with magnetization transfer.

PURPOSE: To compare image contrast and lesion conspicuity of enhancing intracranial lesions obtained with T1-weighted and magnetization transfer T1-weighted spin-echo sequences after administration of standard (0.1 mmol/kg body weight) and triple doses of gadobutrol. METHODS: Twenty-four patients with a total of 34 enhancing intracranial lesions were studied with T1-weighted and magnetization transfer T1-weighted spin-echo MR imaging. An incremental dose technique was used with intravenous injections of 0.1 and 0.2 mmol/kg body weight gadobutrol. Lesion-to-white matter contrast and white matter-to-edema contrast were calculated. RESULTS: The lesion-to-white matter contrast of the magnetization transfer T1-weighted studies was significantly higher than that of the T1-weighted studies when identical doses of gadobutrol were compared. The lesion-to-white matter contrast was not significantly different on the triple-dose T1-weighted study and the standard-dose magnetization transfer T1-weighted study. Two lesions were visible only on the standard-dose magnetization transfer T1-weighted and the triple-dose studies. CONCLUSION: Standard-dose magnetization transfer T1-weighted and triple-dose T1-weighted spin-echo MR studies are equally well suited to increase the lesion-to-white matter contrast in patients with enhancing intracranial lesions. Triple-dose magnetization transfer T1-weighted studies further increase lesion-to-white matter contrast but do not show additional lesions.

Adult↗
PubMedDate not supplied

Potential of CT angiography in acute ischemic stroke.

PURPOSE: To study the ability of CT angiography to show intracranial arterial occlusion and collateral blood flow in patients with acute stroke. METHODS: Twenty-one patients with acute nonhemorrhagic stroke were studied prospectively with conventional CT, CT angiography, and digital subtraction angiography. On the basis of CT angiographic findings, two neuroradiologists independently assessed the site of arterial occlusion, the contrast enhancement in arterial branches beyond the occlusion as a measure of collateral blood supply, and the extent of diminished parenchymal enhancement; they then predicted the extent of ischemic infarction. RESULTS: Both raters correctly assessed all trunk occlusions of the basilar artery (n = 4), the internal carotid artery (n = 4), and the middle cerebral artery (n = 9). The chance adjusted interrater agreement was kappa = .78. The assessment of branch occlusions of the middle cerebral artery was less reliable. The agreement rate in judging the collateral state in 17 occlusions in the anterior cerebral circulation was 88%. The size of 21 (62%) of 34 hemispheric infarctions was predicted correctly. CONCLUSION: CT angiography quickly and reliably adds important information to conventional CT studies in cases of acute ischemic stroke. It shows the site of occlusion, the length of the occluded arterial segment, and the contrast-enhanced arteries beyond the occlusion as an estimate of collateral blood flow.

Adult↗