Monday, 4 June 2018

PERFUSION IMAGING ---BASICS

-------Perfusion magnetic resonance (MR) imaging techniques are widely used in the clinical work-up of brain tumors because of their ability to help quantify tumor microvessel proliferation and permeability and thus to measure changes associated with neoangiogenesis, which correlate with tumor malignancy. 

-----Dynamic susceptibility contrast (DSC) MR imaging  has been extensively explored for glioma grading , for prognostic assessment , and for differentiating between recurrent tumor and posttreatment changes . 

-----Dynamic contrast material–enhanced (DCE) MR imaging has been recently introduced in the preoperative assessment and follow-up of brain tumors. 

------The DCE signal intensity– time curve reflects a combination of tissue perfusion, microvessel permeability, and extravascular-extracellular space , thus allowing for a multiparametric characterization of tumor microvasculature. 

------The advantages of DCE over DSC are fewer susceptibility artifacts and the quantification of blood-brain barrier (BBB) integrity; indeed, the main interest for DCEderived metrics was initially focused on the volume transfer constant (Ktrans), a permeability marker correlating with BBB disruption and malignancy . 



----The advantage of DSC over DCE is better temporal resolution, allowing better estimation of blood volume. 

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