The Physiological Significance of the Tmax Parameter in Bolus Tracking MRI
Christensen S, Karstoft H, Butcher K, Davis S, Wu O, Ostergaard L, Hjort N
The Tmax parameter calculated in bolus tracking studies has proved a promising penumbra marker, yet an interpretation of the pathophysiology it reflects is lacking. We investigate which physical parameters affect Tmax by using simulations and then subsequently use the results to examine 2 acute stroke patients. We conclude that Tmax reflects primarily the time to travel of blood from the site of AIF selection to the tissue and to a lesser extent MTT. Tmax has several attractive features as a metric in acute stroke but sources of confounders do exist and must be taken into account when interpreting data.