Time-to-Maximum (Tmax)

Time-to-Maximum (Tmax) is a perfusion parameter used both in CT perfusion and MRI perfusion and reflects the time delay between the contrast bolus arriving in the proximal large vessel arterial circulation (arterial input function) and the brain parenchyma . It is calculated by deconvoluting the arterial input function .

Although Tmax is widely used in defining tissue at risk of infarction in the setting of ischemic stroke it is susceptible to a variety of distortions particularly in the setting of inflow vascular abnormalities .