A method and system for quantitation of blood flow rates by using digital subtraction angiographic (DSA) images, wherein the spatial shift of the distribution of contrast material injected into an opacified vessel in the acquired angiographic images is analyzed as a bolus of the contrast material proceeds through the vessel. In order to determine the distance that the bolus travels between image acquisitions, there is obtained from the DSA images the distribution of vessel contrast along the length of the vessel, called and "distance-density" curve. The distance that the contrast material travels during the time between two images acquisitions is determined by means of cross correlation of the two respective distance-density curves. The flow rate between the image acquisitions is calculated by multiplying this distance by the frame rate and the vessel cross-sectional area which is estimated from the vessel size assuming a circular cross section. Thus, for high frame-rate acquistions, instantaneous blood flow rates can be determined. The method and system are particularly useful for measurement of pulsatile blood flow rates.
The present invention relates to an ultrasonic synthetic aperture diagnostic apparatus which detects information concerning an internal structure of an object to be examined by making each of a plurality of arranged transducers sequentially emits an ultrasonic pulse signal into the object in turn, receiving each ultrasonic echo reflected by the internal structure of the object by the plurality of transducers in each ultrasonic scanning cycle, and obtaining information concerning the internal structure of the object on the basis of input signals provided by the plurality of transducers. The present invention is intended to provide an ultrasonic synthetic aperture diagnostic apparatus capable operating at a high frame rate and of forming a clear picture of high quality even if the object is moving. The ultrasonic synthetic aperture diagnostic apparatus comprises a displacement measuring means which determines displacement vectors indicating the displacements of the picture elements between two focused input pictures obtained in two ultrasonic scanning cycles for a plurality of focused input pictures, and a displacement integrating means which determines integrated displacement vectors indicating the displacements of the picture elements of a focused input picture from those of a predetermined reference focused input picture by integrating displacement vectors of the corresponding picture elements in a plurality of focused input pictures.
Temporal variations in backscatter from an ultrasound contrast agent located in the vascular system and induced by movement of the scatterers are used to visualize the presence of contrast agent by determining areas where correlation between successive ultrasound images is poor. This low level of correlation from intravascular contrast agent movement permits distinction between stationary bulk tissue and moving bulk tissue since movement of the latter solid tissue scatterers is correlated.
A method for visualizing the choriocapillaris of the eye in a sequence of ICG angiographic images comprising subtracting each image in the angiographic sequence from a succeeding image. In practice, a modified fundus camera is used to provide digitized images which are subtracted pixel by pixel. To better visualize aberrant vascular structures such as choroidal neovascularization (CNV), a fundus camera is modified with a polarizing filter in front of the light source and an analyzing polarizer in front of the video camera. This results in the suppression of unwanted scattered fluorescence to the extent that the CNV can be better visualized. To assist the surgeon in treating aberrant vascular structures with laser photocoagulation therapy, a fundus camera is provided with two light sources and two barrier filters operating synchronously to produce and pass two different fluorescences thereby generating precisely superimposable angiographs to aid in aiming the laser.
An MRI system produces a series of image frames of a blood vessel using a cardiac gated, M-mode Fourier-velocity-encoding pulse sequence. The pulse-wave velocity of a velocity wave traversing the field of view of the image frames is determined by cross correlating a selected reference image frame with the other image frames to locate the relative position of the velocity wave in each of those other image frames, and calculating the propagation velocity of the velocity wave from its relative positions in those other image frames.
An ultrasonic diagnostic system is provided that automatically measures a volumetric flow rate of a vessel presented on a graphical display by estimating the vessel size and direction. The Doppler information signals received from an ultrasonic transducer include frequency components representing fluid flow through a region of interest. The operator selects a vessel represented graphically on the display in which a volumetric flow rate measurement is desired. The ultrasonic diagnostic system then performs a search in a plurality of directions that extend radially outward from a location within the vessel for an upper and a lower set of edge points that correspond to inner wall surfaces of the vessel. Once the upper and lower set of edge points are identified, curves are fitted through the respective sets of edge points to define respective estimates of the inner wall surfaces. Next, an angular difference between the respective curves and a beam direction of the Doppler information signals is measured. Finally, a volumetric flow rate measurement of the selected vessel can be derived within a region defined by the respective curves and based on the measured angular difference.
