A system comprising one or more processors configured to cause the system to: receive fluorescence image data representing an image of tissue of a subject; determine when a first onset of fluorescence in the tissue occurs by determining when a portion of the tissue has a fluorescence intensity value that is greater than a first predetermined threshold intensity value; determine when the portion of the tissue is well perfused by determining that the portion of the tissue has a fluorescence intensity value that is greater than a second predetermined threshold intensity value, the second predetermined threshold intensity value being greater than the first predetermined threshold intensity value; in response to determining when the portion of tissue has a fluorescence intensity value that is greater than the second predetermined threshold intensity value, identify at least one area of the portion of the tissue having little or no fluorescence by identifying at least one area of the portion of the tissue having a fluorescence intensity value that is less than a third predetermined threshold intensity value; determine when first onset of fluorescence occurs in the at least one area by determining when the at least one area of the portion of the tissue has a fluorescence intensity value that is greater than a fourth predetermined threshold intensity value; calculate time between when the at least one area of the portion of tissue has a fluorescence intensity value that is greater than the fourth predetermined threshold intensity value and when the portion of the tissue has a fluorescence intensity value that is greater than the first predetermined threshold intensity value; and if the calculated time is greater than a predetermined time, provide a notification based on the calculated time being greater than the second predetermined time. receive fluorescence image data representing an image of tissue of a subject; determine when a first onset of fluorescence in the tissue occurs by determining when a portion of the tissue has a fluorescence intensity value that is greater than a first predetermined threshold intensity value; determine when the portion of the tissue is well perfused by determining that the portion of the tissue has a fluorescence intensity value that is greater than a second predetermined threshold intensity value, the second predetermined threshold intensity value being greater than the first predetermined threshold intensity value; in response to determining when the portion of tissue has a fluorescence intensity value that is greater than the second predetermined threshold intensity value, identify at least one area of the portion of the tissue having little or no fluorescence by identifying at least one area of the portion of the tissue having a fluorescence intensity value that is less than a third predetermined threshold intensity value; determine when first onset of fluorescence occurs in the at least one area by determining when the at least one area of the portion of the tissue has a fluorescence intensity value that is greater than a fourth predetermined threshold intensity value; calculate time between when the at least one area of the portion of tissue has a fluorescence intensity value that is greater than the fourth predetermined threshold intensity value and when the portion of the tissue has a fluorescence intensity value that is greater than the first predetermined threshold intensity value; and if the calculated time is greater than a predetermined time, provide a notification based on the calculated time being greater than the second predetermined time.