A method, comprising: scanning a region of interest, during a contrast agent based computed tomography perfusion scan, at a predetermined temporal sampling rate during contrast agent uptake in the region of interest, and generating time frame data indicative of the scanned region of interest; identifying a predetermined change in an amount of contrast agent in the region of interest from the time frame data; scanning the region of interest at a lower temporal sampling rate during pre-contrast agent uptake; scanning the region of interest at a second lower temporal sampling rate during contrast agent washout, wherein the lower temporal sampling rate and the second lower temporal sampling rate are lower than the predetermined temporal sampling rate during the contrast agent uptake, respectively; and switching from the predetermined temporal sampling rate to the second lower temporal sampling rate in response to identifying the predetermined change being a decrease in the amount of the contrast agent in the region of interest, wherein the decrease is indicative of contrast agent washout, wherein the predetermined temporal sampling rate is varied during contrast agent uptake, wherein the second temporal sampling rate is equal to the lower sampling rate and lower than the higher temporal sampling rate, and wherein the method further comprises sensing a motion cycle of the region of interest; identifying a sub-portion of the motion cycle; scanning the region of interest only during the sub-portion of the motion cycle; scanning using a sparse spatial sampling; reconstructing the time frame data using a sparse reconstruction algorithm; and using a lower tube current during pre-contrast agent uptake scanning and contrast agent washout scanning and using a higher tube current during contrast agent uptake scanning, wherein the higher tube current is greater than the lower tube current. scanning a region of interest, during a contrast agent based computed tomography perfusion scan, at a predetermined temporal sampling rate during contrast agent uptake in the region of interest, and generating time frame data indicative of the scanned region of interest; identifying a predetermined change in an amount of contrast agent in the region of interest from the time frame data; scanning the region of interest at a lower temporal sampling rate during pre-contrast agent uptake; scanning the region of interest at a second lower temporal sampling rate during contrast agent washout, wherein the lower temporal sampling rate and the second lower temporal sampling rate are lower than the predetermined temporal sampling rate during the contrast agent uptake, respectively; and switching from the predetermined temporal sampling rate to the second lower temporal sampling rate in response to identifying the predetermined change being a decrease in the amount of the contrast agent in the region of interest, wherein the decrease is indicative of contrast agent washout, wherein the predetermined temporal sampling rate is varied during contrast agent uptake, wherein the second temporal sampling rate is equal to the lower sampling rate and lower than the higher temporal sampling rate, and wherein the method further comprises sensing a motion cycle of the region of interest; identifying a sub-portion of the motion cycle; scanning the region of interest only during the sub-portion of the motion cycle; scanning using a sparse spatial sampling; reconstructing the time frame data using a sparse reconstruction algorithm; and using a lower tube current during pre-contrast agent uptake scanning and contrast agent washout scanning and using a higher tube current during contrast agent uptake scanning, wherein the higher tube current is greater than the lower tube current.