MR perfusion weighted imaging

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MRI

There are three techniques in wide use to derive one or more perfusion values

• Dynamic susceptibility contrast (DSC) MR perfusion
• Most frequently used techniques
• Relies on the susceptibility induced signal loss on T2*-weighted sequences which results from a bolus of gadolinium-based contrast passing through a capillary bed.
• Cons
• Because this technique relies upon detecting signal loss due to small amounts of contrast, if there is significant signal loss due to the presence of calcification or blood products, or due to artifact from adjacent dense bone or aerated sinuses, obtained values will not be reliable. Similarly, values in a region immediately adjacent to large vessels will also be affected

• Dynamic contrast enhanced (DCE) MR perfusion
• Calculates perfusion parameters by evaluating T1 shortening induced by a gadolinium-based contrast bolus passing through tissue. The most commonly calculated parameter is k-trans.

• Arterial spin labelling (ASL) MR perfusion

Derived values

• Time to peak (TTP)

• Mean transit time (MTT)

• Cerebral blood volume (CBV)

• Cerebral blood flow (CBF)

• Negative enhancement integral (NEI)

• K-trans

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