Artikel
Multimodality MR imaging: monitoring of haemodynamic changes and cerebral ischemia in subarachnoid haemorrhage
Monitoring hämodynamischer Veränderungen bei SAB-Patienten durch multimodales MRT
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Autoren
Veröffentlicht: | 4. Mai 2005 |
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Gliederung
Text
Objective
Better measures of cerebral tissue perfusion and earlier detection of ischemic injury are needed for an effective therapy in subarachnoid haemorrhage (SAH). MRI (perfusion and diffusion weighted) first established to diagnose acute ischemic stroke has got a high sensitivity and sensibility to verify cerebral ischemic regions. The perfusion weighted MRI allows the detection of changes in the microvascular path line, which are not detectable by other image modalities and may help to an early start of appropriate therapy.
Methods
In 6 Patients (WFNS grades 2-5) with aneurysmal SAH daily clinical- and transcranial doppler -examination, perfusion - and - diffusion MRI were performed. For the perfusion weighted MRI we used the indicator dilution theory. During the pronounced phase of vasospasm (VSP), additionally a cerebral angiography as a gold standard for the macrovascular path line was done. Our results of this three different methods, advantages and disadvantages were demonstrated and correlated. At last to make a statement of fundamental importance on the different methods the discussion with literature follows.
Results
MR-angiography and cerebral angiography shows a high correlation for detection of VSP. TCD does not assess the haemodynamic changes in the microvascular path line. Increased time to peak (TTP) and mean transit time (MTT) first detect microcirculatory changes. An increased relative cerebral blood volume (rCBV) in combination with a constant or mild decreased cerebral blood flow (rCBF) indicating a sufficient cerebral perfusion. A highly increased TTP and MTT in combination with a decreased rCBV and rCBF is highly correlated to DIND.
Conclusions
The reported results give hope that multimodality MRI is a non-invasive method of the future for establishing the diagnosis of vasospasm very early after haemorrhage and prevent vasospasm related ischemia. In order to be able to make monitoring more viable critical values of the MRI parameters characterising an imminent ischemia have to be established.