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A b s t r a c t A new b l o o d f l o w imaging system i s d e s c r i b e d t h a t colrbines a c o n v e n t i o n a l p u l s e d Doppler dev i c e and a newly developed a u t o c o r r e l a t o r . I n t h e system b l o o d f l o w w i t h i n a g i v e n cross s e c t i o n o f a l i v e organ i s d i s p l a y e d i n r e a l -t i m e . The d i r e c t i o n o f b l o o d f l o w and i t s variance a r e expressed by means o f a d i f f e r e n c e i n c o l o r and i t s hue, r e s p e c t i v e l y . Experiments were conducted w i t h a mechanical and an e l e c t r i c a l scanner, and good agreement w i t h the t h e o r y was obtained. S t u d i e s on c l i n i c a l s i g n i f i c a n c e have a l s o been c a r r i e d o u t f o r normal and diseased h e a r t s , and s u c c e s s f u l r e s u l t s have been found. 1. I n t r o d u c t i o n Tomographic imaging t h a t employs u l t r a s o n i c echoes has achieved o u t s t a n d i n g advances i n r e c e n t y e a r s , and today u l t r a s o n i c d i a g n o s t i c equipment has become an i n d i s p e n s a b l e t o o l f o r c l i n i c a l use. However, b l o o d flows through t h e h e a r t and b l o o d vessels, and s i g n i f i c a n t c o n t r i b u t i o n s t o d i a g n o s t i c s would be made i f t h e b e h a v i o r o f such f l o w s c o u l d be made. From such a s i m p l e concept, we developed a device t h a t d i s p l a y s b l o o d f l o w movements on a cross s e c t i o n o f t h e h e a r t o r b l o o d vessels i n r e a l time, u s i n g an a u t o c o r r e l at i o n technique, and we have p r e v i o u s l y r e p o r t e d an o u t l i n e o f i t s o p e r a t i o n [1],[2]. F o l l o w i n g t h a t , we described t h e d e t a i l s o f t h e system [3],[4], t o g e t h e r I n t h e well-known B-mode i n s t r u m e n t s , o n l y 0090-5607/85/0000-0953 $1.00 0 1985 IEEE I m p o r t a n t aspects t h a t p r o v i d e t h e f l o w i n f o rmation e f f e c t i v e f o r d i a g n o s i s a r e 1 ) f l o w d i r e ct i o n , 2 ) mean f l o w v e l o c i t y , and 3) flow disturbance. A. Flow D i r e c t i o n I n t h e p u l s e echo i n s t r u m e n t employing one u l t r a s o n i c transducer, t h e f l o w component on t h e sound beam a x i s i s measured. By d e t e c t i n g t h e p o l a r i t y o f t h e Doppler frequency s h i f t o f echoes w i t h r e s p e c t t o t h e frequency t r a n s m i t t e d , t h e f l o w d i r e c t i o n ( i . e . , f o r w a r d f l o w o r r e v e r s e f l o w ) i s d i s c r i m i n a t e d . 6. Mean Flow V e l o c i t y frequency s p e c t r a o f echoes. When a sound w i t h an a n g u l a r frequency o f 00 i s t r a n s m i t t e d i n t o blood, t h e echo s i g n a l e ( t ) r e c e i v e d from the b l o o d i s d e s c r i b e d as f o l l o w s [6]: Mean b l o o d f l o w v e l o c i t y i s e s t i m a t e d f r o m t h e where z ( t ) i s t h e complex envelope s i g n a l o f e ( t ) and i s d e s c r i b e d as z ( t ) = x ( t ) + j...

Blood flow information has been available without negatively affecting human tissues since ultrasonic Doppler techniques were introduced in medical diagnosis. But difficulties with conventional techniques include the acquisition and display of two-dimensional data in real-time. To overcome such difficulties, we developed a real-time twodimensional blood-flow imaging system using a complex autocorrelation technique which could display flow direction, mean flow velocity, and flow variance. In this system, blood-flow data are displayed in color and superimposed over a blacklwhite tomographic image (tissue form image). This paper describes an outline of the principle, the configuration of the new system and relevant experimental results. It also discusses problems that arise in employing the technique. Clinical evaluation at hospitals which use the system has proven that the system is very useful for the diagnosis of various diseases.

A newly developed two-dimensional blood flow imaging system which uses ultrasound is described, in which blood flow in a given cross section of a live organ is displayed in real time. To perform this, an autocorrelation technique is used. Obtained blood flow data are displayed in color on a TV screen superimposed on black/white tissue images. The flow direction, speed and variance are expressed by differences in color and brightness. Experiments were conducted with a mechanical and an electrical scanner and good agreement with the theory was obtained. Studies on clinical significance have also been carried out for normal and diseased hearts with successful results.

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