Data acquisition methods for reduced motion artifacts and applications in oct angiography

Abstract

Systems and methods for reducing the effects of motion on functional optical coherence tomography (OCT) imaging are described. Embodiments including post-processing and motion tracking are presented. A preferred embodiment in which functional OCT data is collected and analyzed for motion as a multiple scan unit is described. An extension of the invention to the collection of large field of view or montaged functional OCT data sets is also presented.

1 . A method of collecting and analyzing functional OCT imaging data of an eye of a patient, said method comprising:
 acquiring a plurality of OCT measurement data from the eye of a patient, said OCT measurements being acquired by scanning the eye with a beam of light using a scanning device;   monitoring the eye position to detect transverse motion of the eye while acquiring the plurality of measurement data, and wherein the eye position information is used to ensure that at least two OCT measurements are acquired from the same position on the eye;   analyzing the at least two OCT measurements to identify structural or functional change within the eye in the time between the two measurements;   generating an image of the identified structural or functional change; and   storing or displaying the image.   
     
     
         2 . A method as recited in  claim 1 , wherein measurement data is rejected if eye motion has caused it to be displaced relative to another measurement. 
     
     
         3 . A method as recited in  claim 1 , wherein measurement data from the same location are re-acquired if eye motion is detected during the acquisition 
     
     
         4 . A method as recited in  claim 1 , wherein the measurement data are A-scans. 
     
     
         5 . A method as recited in  claim 1 , wherein the measurement data are B-scans. 
     
     
         6 . A method as recited in  claim 1 , wherein the analyzing step involves calculating the difference between the at least two measurements, and wherein the structural or functional change is flow. 
     
     
         7 . A method of collecting and analyzing functional OCT imaging data of the retina of the eye, said method comprising:
 acquiring a set of OCT data of the retina comprising a plurality of cluster scans, wherein each cluster scan comprises at least two measurements covering approximately the same transverse locations on the retina;   monitoring the eye position to detect eye motion while acquiring each cluster scan, and wherein the measurements associated with at least one cluster scan are rejected if eye motion has occurred during the acquisition of said cluster scan;   analyzing the OCT data in each cluster scan to identify structural or functional change within the eye in the time between the two measurements;   generating an image of the structural or functional change; and   storing or displaying said image.   
     
     
         8 . A method as recited in  claim 7 , wherein a cluster scan is re-acquired if eye motion is detected during the acquisition. 
     
     
         9 . A method as recited in  claim 7 , wherein the eye position monitoring is accomplished by a fundus imaging based tracking system. 
     
     
         10 . A method as recited in  claim 7 , wherein the update rate of the fundus imaging system is synchronized to the time required to acquire a single cluster scan. 
     
     
         11 . A method as recited in  claim 7 , wherein the analyzing step involves calculating the difference between the at least two measurements, and wherein the structure or functional change is flow. 
     
     
         12 . A method of collecting and analyzing large field of view functional OCT imaging data of an eye of a patient, said method comprising:
 acquiring a large field of view data set of the eye comprising at least two smaller data field of view sets, wherein each smaller data set is centered on a different location within the eye, and each smaller data set contains at least two measurements taken at approximately the same location on the eye;   monitoring the eye position while acquiring the smaller data sets, and wherein the location of the acquisition of each of the smaller data sets is determined based in part on the monitored eye position;   analyzing the at least two measurements taken at approximately the same location in each smaller field of view data set to identify structural or functional change within the eye in the time between the two measurements;   generating an image of the structural or functional changes over the large field of view by combining the structural and functional changes in the smaller field of view data sets; and   storing or displaying the image.   
     
     
         13 . A method as recited in  claim 12 , wherein the eye position monitoring accounts for transverse motion during data acquisition. 
     
     
         14 . A method as recited in  claim 12 , wherein the eye position monitoring accounts for tilt changes occurring during data acquisition. 
     
     
         15 . A method as recited in  claim 12 , wherein the eye position monitoring accounts for angle changes during data acquisition. 
     
     
         16 . A method as recited in  claim 12 , wherein the image is a composite en face vasculature image. 
     
     
         17 . A method as recited in  claim 12 , wherein the patient is allowed to sit back from the instrument between acquisition of the at least two smaller data sets. 
     
     
         18 . A method as recited in  claim 10 , wherein the data acquisition is initiated by a single interaction with a user interface and the system automatically acquires the at least two smaller data sets without requiring further interaction with the user interface. 
     
     
         19 . A method as recited in  claim 7 , wherein the analyzing step involves calculating the difference between the at least two measurements, and wherein the structure or functional change is flow. 
     
     
         20 . An OCT system for collecting and analyzing functional OCT image data, said system comprising:
 an OCT measurement system for acquiring a plurality of measurements from the eye of a patient, said measurement system including a scanner for scanning a beam of light over the eye;   a tracking system for monitoring the location of the eye during the OCT measurement acquisition;   a processor for analyzing the tracking information for transverse motion and for controlling the direction of the scanner of the measurement system to ensure that at least two OCT measurements are acquired when the scanned beam of light is at the same position on the eye, said processor for analyzing the at least two measurements to identify structural or functional changes within the eye in the time between the two measurements; and   a display for displaying an image of the structural or functional changes.   
     
     
         21 . An OCT system as recited in  claim 20 , wherein the tracking system is a fundus imaging system. 
     
     
         22 . An OCT system as recited in  claim 20 , wherein the processor instructs the OCT measurement system to re-acquire one or more measurements if transverse motion exceeding a pre-defined threshold is detected.