Tissue at Risk
Therapeutic Decisions in Ischemic Stroke
The differentiation of reversibly and irreversibly damaged brain tissue is crucial for the appropriate therapy of stroke. Siemens' advanced imaging technology supports the demarcation of possibly infarcted brain areas and tissue at risk. Siemens imaging thus provides a base of evidence for decisions on systemic thrombolytic therapy - even beyond the 4.5 hours threshold.
MR diffusion-weighted imaging (DWI) is one of the most sensitive and specific techniques available for detecting ischemic lesion even in early stages of infarction. The estimated sensitivity of DWI for the diagnosis of ischemic stroke is about 80 - 90% in a general sample of emergency patients and rises up to near 100% in selected patient populations.1 Together with perfusion-weighted imaging (PWI) it enables differentiation of viable hypoperfused tissue from a probably nonviable irreversible infarction core.
Tissue at risk of permanent infarction (ischemic penumbra) can be approximated by a pattern of critical hypoperfusion in MRP without associated diffusion abnormalities in DWI (diffusion-perfusion mismatch). Brain tissue of the ischemic penumbra might profit from thrombolytic therapy. The prognostic value of a diffusion-perfusion mismatch has not been fully established, though, and the outcome of reperfusion might differ significantly from predictions based on the mismatch alone.
Siemens supports your treatment decisions with fast, comprehensive, and reliable MR imaging technology and workflows.
Perfusion CT imaging techniques can detect ischemic brain areas with a sensitivity of up to 95% and a specificity of up to 100%, and may help to identify the ischemic penumbra (tissue at risk) of a stroke.2
Whole-brain perfusion CT imaging provides a simultaneous analysis of the blood volume in all parts of the brain. Hypoattenuation in the scans is assumed to be associated with ischemia.
Dynamic contrast-enhanced perfusion CT imaging can provide absolute values for cerebral blood flow, mean transit time, and cerebral blood volume. Thanks to Siemens' unique Adaptive 4D Spiral mode of Siemens SOMATOM® Definition scanners, dynamic perfusion CT imaging is no longer limited to a restricted brain area but allows for tissue-at-risk evaluation of the whole brain.
syngo.CT Neuro Perfusion
syngo.CT Neuro Perfusion visualizes blood perfusion in the brain. In ischemic stroke this can help to estimate the size of the core infarct as well as the extent of tissue at risk to infarct (penumbra) that is potentially salvageable with further therapy. These insights may support the clinician to better decide on optimal treatment. It is suitable for routine 24/7 use and guided workflow delivers results in 5 easy steps. Benefits also include a tissue-at-risk model with user defined perfusion parameters (e.g. CBF, CBV, TTD, TTS, TTP, MTT) and auto grey matter segmentation to focus on the relevant tissues leading to better quantification accuracy.
AX: syngo DynaPBV Neuro
For stroke patients, visualization of brain perfusion is of special importance before, during, and after neuroradiological interventions. Siemens syngo® DynaPBV Neuro is an edge-of-technology neuro-imaging software that allows for differentiated stroke diagnosis right at the angio suite. Monitoring brain parenchymal blood volume (PBV) and perfusion imaging of the entire brain at the site of intervention saves critical time, avoids patient transportation, and possibly reduces radiation exposure.
1Source: Schellinger: Schellinger PD et al., Neurology 2010;75:177-185
2Source: Duffis EJ et al, Neurosurg Focus 2011; 30(6):E5