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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...

SUMARYA noninvasive method for real time blood-flow imaging using ultrasound has long been required in the fields of cardiology, and cardiovascular surgery. Recently, we developed a method of twodimensional Doppler echocardiography (hereafter abbreviated as "2 -D Doppler") for clinical use which allows us to obtain noninvasively, intracardiac blood-flow images in real time. The main purpose of this paper is to describe the newly developed blood-flow imaging system "2-D Doppler" and to demonstrate its clinical usefulness in acquired valvular diseases, particularly in the evaluation of valvular regurgitation.The device, in principle, combines a conventional pulsed-Doppler system and a newly developed auto-correlator, in which bloodflow images within a given cross section of a beating heart are noninvasively displayed in real time, simultaneously with conventional two-dimensional echocardiograms. The system can provide three kinds of information, direction, velocity and turbulence of blood flow.The 2-D Doppler examinations were carried out on 72 patients with acquired valvular diseases whose diagnoses were confirmed by From *the First

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