The calculation of brain mean transit time (t) using IADSA and its clinical application

Abstract

It is important to know cerebral blood dynamics of cerebral infarcts. Intra-arterial Digital Subtraction Angiography (IADSA) is widely used in cerebrovascular diseases because of its superority in high sensitivity of time and contrast medium, and time-density curves of any area can be given easily at real time by A/D converter.
Brain mean transit time (t) (which means time from internal carotid artery to internal jugular vein) and partial brain mean transit time (tp) (which means time from internal carotid artery to cortical area in the middle cerebral artery) were calculated in the damaged hemisphere and non-damaged one by time-density curves using Hamilton's dye dilution method in 84 middle cerebral artery infarcts. We discussed clinical application of t and tp to CT groups divided by lesion and low density area, and Activity of Daily Living (ADL). The larger the low density area is, the longer t becomes prolonged both in the damaged hemisphere and the opposite one. t was mutually correlated in all CT groups and was measured over 6.0 sec except normal group that showed 4.32 ± 0.45 sec. However tp wasn't mutually correlated in CT groups and ADL ones. t is clinically useful compared to tp because of the former reflecting physical conditions of arterial and venous vessels. The better ADL is, the shorter t becomes. Excellent prognostic group and bad ones can be classified whether t indicates below 6.0 sec or not.
We concluded that t is one of the valuable parameters which reflects cerebral blood flow and can be useful to determine prognosis of cerebrovascular patients.