Time to peak (TTP)
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Time-to-peak (TTP) is the time at which contrast concentration reaches its maximum. For example, for a particular dynamic susceptibility contrast (DSC) imaging acquisition in which images are acquired every 1.5 seconds, possible TTP values could include 20.0 seconds, 21.5 seconds, 23.0 seconds, etc.
The advantages of TTP in this role are:
- defects on TTP maps are conspicuous and usually well-defined
- TTP is a reproducible technique, in that measurements obtained by different centers from a single data set are similar, with less technique-dependent artifacts to complicate interpretation
TTP is very sensitive to motion artifacts and noise, so some algorithms that perform motion correction and pre-filtering will produce differing results. Some algorithms also perform curve fitting to obtain TTP.
The primary disadvantage of using TTP is that TTP can be prolonged in a wide variety of acute and chronic hemodynamic conditions. TTP prolongation may be caused by reduced blood flow, but also occurs when the arrival of the injected contrast bolus is delayed, but cerebral blood flow (CBF) is normal.