Imaging abnormalities in vascular response

A system for assessing an abnormality in a test subject's vascular response to a vasoactive stimulus, the system comprising:

• a sequential gas delivery system for generating the vasoactive stimulus in a region of interest of the test subject's brain, the vasoactive stimulus comprising at least one targeted change in the subject's end-tidal concentration of carbon dioxide;
• an imaging system for measuring a test subject vascular response signal, the test subject vascular response signal comprising at least a time course representing the test subject's vascular response to the vasoactive stimulus in the region of interest of the test subject's brain, wherein the vascular response signals are quantifiable from a surrogate measure of blood flow in the region of interest;
• and
• a processor connected to the system for generating the vasoactive stimulus and the imaging system, the processor configured to:
• time-align the test subject vascular response signal with the vasoactive stimulus to the point of maximum correlation;
• calculate a score for the test subject, the score representing a comparison between the test subject vascular response signals for the region of interest and a respective computed statistical value for a corresponding region of interest, the computed respective statistical value representing a normal distribution of vascular response signals in a plurality of control subjects;
• wherein the respective computed statistical value for the corresponding region of interest is computed based on a set of vascular response signals obtained for the plurality of control subjects, each vascular response signal representing a vascular response to the vasoactive stimulus in the corresponding region of interest of each control subject's brain, the respective region of interest coordinates co-registered to a standardized space based on a set of anatomic landmarks;
• wherein the vasoactive stimulus in the region of interest of the test subject's body is approximately the same as the vasoactive stimulus in the corresponding region of interest of each control subject's body;
• and
• wherein the respective computed statistical value for the corresponding region of interest is computed by calculating a mean and a standard deviation of the vascular response signals for the corresponding region of interest;
• and
• mapping the score onto an anatomical representation of the standardized space to produce a statistical map.