Patent ID: 9351649
Filing Date: 2016-05-31
CPC Classification: A61B,G06T

Claim Text:
1. A method for determining an arterial pulse transit time between a proximal and distal region of a subject of interest from source video images acquired using a video imaging system, the method comprising: receiving time-varying source images acquired over at least one channel of a video imaging system, said source images comprising video images captured of a proximal and distal region of an area of exposed skin of a subject of interest in which plethysmographic signals can be registered and at least one background region in which plethysmographic signals cannot be registered, and said proximal and distal regions and said background region being exposed to the same environmental factors; extracting, from said source images a first time-series signal for said proximal region and a second times series signal for said distal region and at least one background region time-series signal; subtracting said first time-series signal and said background region times-series signal to obtain environmentally compensated time-series signal for said proximal region; subtracting said second time-series signal and said background region times-series signal to obtain environmentally compensated time-series signal for said distal region; computing a first phase angle φ computing a second phase angle φ plotting said computed phases with respect to frequency to obtain respective phase vs frequency curves for each of said proximal and distal regions; computing respective slopes T computing a difference between said slopes T storing, using a processor, said arterial pulse transit time to a storage device.