1

Historical Perspective of the Development of
Diagnostic Ultrasound in Cardiology
Motonao Tanaka
Abstract—The diagnostic application of ultrasound inclinical medicine advanced uniquely in the ﬁeld of cardiology. The cardiovascular system is a most suitable organ
for the application of ultrasound for use in obtaining information regarding structure and function, which are diﬃcult
to obtain using other diagnostic methods and which are indispensable for accurate diagnosis of diseases.
However, because of the complicated structure and characteristics of the functioning of the heart, unique and creative technologies had to be developed for practical applications.
In this paper, perspectives of the historical developmentof ultrasonic diagnostic technology, which originated as key
elements for improving clinical cardiology and which developed in our laboratory, are systematically presented.
First, as the most important aﬀair in the ﬁrst step of clinical application of ultrasound, the introduction and establishment of the practical use of the focused ultrasound to
the ultrasonic pulse reﬂection method are described. Next,
we address two-dimensional echocardiography and its related technology such as tomo-kymography, combination of
M-mode method, Doppler method, and tomography etc.
Then we discuss ultrasonic tissue characterization in cardiology by echo method and the development and applicationof ultrasonic microscopy for biomedical use. We address
modulated ultrasonic Doppler method including the twodimensional Doppler method. Finally, after introducing thedata processing technique, we conclude with new technology for deducing the functional information on cardiovascular function, such as contractility of the local myocardium,
local ﬂow volume, and local pressure in the heart chambers
and their two-dimensional distribution, which are very important for accurate estimation of the heart function.

I. Introductionn clinical medicine, detailed information on the morphological and physiological changes of organs is indispensable for accurate diagnoses of diseases. To obtain such information easily in a non-invasive manner, ultrasonic diagnostic techniques for displaying the structure and functionof tissues and organs were developed in the ﬁfth to sixth
decade of the 20th century [1]–[5].
Three basic techniques were developed for the practicalapplication of ultrasound in the ﬁeld of clinical cardiology. The ﬁrst, M-mode echocardiography, which is also
called the time-position indication method [6], used thepulse reﬂection technique developed by Edler and Hertz
in 1954 [7]. The second, the ultrasonic Doppler method
employed for the measurement of the motion of the reﬂector, such as blood or a cardiac structure, was developed by Satomura and Nimura in 1956 [8], [9]. The third,I

The author is with Tohoku University, Sendai, Japan.

two-dimensional echocardiography, termed the ultrasonocardio-tomography, was developed by Tanaka et al. in 1964[10]–[12]. Two-dimensional display of structure and function information was the essential technique for clinicaldiagnosis, because of the following advantages. First, ananatomical site, i.e., a target object, in a pathological stateor critical condition can be identiﬁed accurately spatiallywith ease. Second, intuitive estimates of abnormalities occurring in the organ can be made safely with ease and inreal time. Accordingly, studies of the ultrasonic imaging ofa human body in two dimensions were begun by several
investigators in the sixth decade of this century [1], [3],[13], [14].
However, at that time, only circular plane transducers
were used generally in echography. Two-dimensional images were made by echo signals obtained from the organs,during ultrasonic scanning, and displayed on a storage oscilloscope as the integrated images that were overlappedwith each echo signal obtained from diﬀerent beam directions. The resolution of the picture, i.e., quality of theimage, was very poor and inadequate for displaying ﬁnely
detailed structures such as those of the heart.
To develop further ultrasonic applications in cardiology
as a diagnostic tool, performance of basic investigations,e.g., analysis of the sound ﬁeld in the medium, the processing of echo signals, etc., were urgently required. This
paper focuses on the work of our laboratory. It is hopedthat it provides a coherent and systematic presentation on
one approach to the goal of applying ultrasound to clinicalcardiology.

II. Introduction of the Sound Field Control
Technique to Diagnostic Ultrasound
A. Design of the Ultrasonic Transducer for
Obtaining High Quality Echograms
In addition to the medical requirements and engineering problems mentioned previously, the following existing
acoustical limitations had to be broken through. According
to the anatomical position of the heart and the acoustic
characteristics of the thorax and the lung [15], the following points are true: 1) the heart is enveloped by the osseous frame, which greatly limits the ultrasonic scan areaon the thorax; 2) the lung, which lies on both sides of theheart, exhibits a very large acoustic attenuation by virtueof the air it contains; 3) the back of thorax contains ac 2002 IEEE

2thick layer of muscle; and 4) the heart pulsates continuously. Accordingly, it had been considered that an ultrasonic two-dimensional picture of the heart was extremely
diﬃcult to obtain in the living state without developmentof more advanced technology.
To solve these anatomical and acoustical problems, it
was necessary to develop the following new techniques:1) control techniques of the radiated sound ﬁeld, especiallya converging technique for making the beam narrower than
the size of observed structure components; 2) methods forcompensating attenuation of ultrasound along the pathway [15] or methods for increasing the acoustic power ofthe weak echoes reﬂected from the target area at remote
distances; and 3) control techniques synchronized with
ECG signals.
Because few theoretical and experimental studies regarding the spatial distribution of the sound ﬁeld had been
published at that time (late 1950s through early 1960s),
Tanaka et al. began to investigate the convergence of soundﬁelds by introducing acoustic lenses and concave transducers in 1963 [16], [17].
Prior to that time, theoretical analyses of the spatial
acoustic pressure distribution of the concave transducer
were carried out using the two new theories. One was originated by Prof. Y. Torikai (Tokyo University) in 1955 [18],1960 [19], and 1962 [20]; the other was originated by S.
Ohtsuki’s ring function in 1972 [21].
These theoretical results were compared with the experimental results of the spatial sound ﬁeld obtained by measuring the intensity of the echo reﬂected from a very small
spherical target, about 0.3 mm in diameter; the target was
moved laterally, in 1-mm intervals in degassed water, in coordination with the echo intensity, thus obtaining a resultthat was proportional to square of the sound pressure at
the target [17]. The theoretical results compared well withthe experimental results particularly because of the improvement of the azimuthal resolving power attributable
to the narrow beamwidth from the converging eﬀect [16],[17].
With the use of Torikai’s theory [20], with the concave
transducer in the ultrasonic reﬂection technique, Tanaka
proposed that better results should follow with the use ofa transducer having the following conﬁguration [17]:R2 /(Aλ) ≤ 4
where R is the transducer radius, A is radius of curvature,and λ is the wavelength in the medium.
Tanaka et al. pointed out that the following favorable
eﬀects were obtained by employing the transducer of thisconﬁguration [17].
• The beam width could be made suﬃciently narrow sothat local selectivity was markedly improved, providing obtainable high resolution and high quality images.
• The length of the Fresnel’ interference zone was madeshorter than that of a plane circular transducer of thesame size, suppressing the near ﬁeld relatively suchthat the proximity immersed method, or direct contact
method, could be applied easily.
• The acoustic power converged so that intensiﬁed echo
signals were readily obtained even in the far distancearea.
• The miniaturization of the transducer and the introduction of the STC circuit were made easier.
The satisfactory eﬀects of using the concave transducer
appeared markedly in the image quality of the actual tomogram of the heart taken by an immersion method, as
shown in Fig. 1. The miniaturization of the transducer
made it possible to perform an intracavitary ultrasonicscan, such as transesophageal scan, etc. [22]. Since then,the converged sound ﬁeld produced by the dynamic focusing method of the annular or phased arrays has been usedwidely in practical echo machines for diagnostic purposes[49]. Additionally, these converging eﬀects of the soundﬁeld of the acoustic lens were applied to the acoustic microscope in 1982 [41], [42].
III. Introduction of the Processing Techniqueto the Echo Signals

After building up the basis of two-dimensional echocardiography to improve the quality of the cross-sectional
image, development and introduction of new technology,
such as sensitivity time control (STC) [23], fast time constant (FTC) [24], logarithmic ampliﬁer, improvement forthe scanning speed and miniaturization of ultrasonic scanner [22], [25], and ECG-triggered control method [26], werecarried out [27]. Thus, Tanaka et al. were the ﬁrst to obtain high quality cross-sectional images of the heart bymechanical sector scanning in 1965 [27].
IV. Development of Ultrasonic Technology for
Obtaining Information on Morphological
Changes in Cardiology

A. Macroscopic Dimension Measurement

To increase the accuracy of morphological measurementof macroscopic cardiac structures, the principle of combining two-dimensional echocardiography and M-mode display was proposed in 1965 [28], [29] (Fig. 2). Thus, in 1970,
various features of cardiac structures, such as thickness ofthe heart and vessel wall, internal and external diameter ofthe chambers, size and shape of the cardiac structure, localized deformity etc., could be estimated on the ultrasoniccross-section image [29], [30]. However, two basic problems
remained: the measurement of the thickness and hardnessof thin tissue, such as valve tissue and vessel wall [31], andtissue characterization of the myocardium and other heartand vessel tissues.

3Fig. 1. High quality ultrasono-cardiotomogram (2-dimensional echocardiogram) of a canine heart at the left ventricular level obtained byusing a concave disk transducer of 30 mm diameter, 100 mm radius of curvature, and 5-MHZ frequency. The heart just after excision was
suspended at the focal area in the water bath. The echo pattern shows the three-layer structure.

B. Measurement of the Thickness andSound Speed of Thin Tissues
When an ultrasonic pulse impinges on a biological specimen placed in a medium for which the speed of sound is
known, two reﬂected pulse signals from the front and theback surfaces of the specimen are produced as shown in
the Fig. 3. In the following, the speed of sound of the immersing medium is Co, the thickness of the specimen isd, the transit time of the ultrasound passing through theimmersing medium the same distance as the thickness ofthe specimen is twd, the speed of sound of the specimen isC, the transmitting time passing through the specimen istsd, and the thickness of the specimen is d [31], [32]:d = C × tsd = Co × twd= Co × (tsd−∆t)where ∆t ≡ tsd−twd. Therefore, C = Co (1 − ∆t/tsd ).
Here, when the two reﬂected signals returned from thefront and the back surface of the specimen are obtained, if
the thickness of a tissue specimen of interest is more than

the wave train length, the two reﬂected signals are separated, and tsd can be measured easily by using the pulse
echo method. However, if the thickness of the specimen
is less than about one-half of the wave train length, thetwo reﬂected signals are not separable, and tsd cannot bemeasured.
Then, a new measuring method, in which sound speed
and thickness of the thin tissue specimen can be estimatedby analyzing the echo signals in the frequency domain, wasdeveloped and introduced to clinical cardiology and tissue
characterization [31]–[33]. In this case, for the accurate
measurement of the tsd , the two reﬂected signals from thefront and the back surface of the specimen are received at
the same time and mixed with each other.
When the received signal thus obtained, in which theinterference is included, is analyzed in the frequency domain by the FFT method, from the interval between two
successive peaks of the frequency spectrum, tsd was accurately estimated.
On the other hand, the time diﬀerence (∆t) between
two reﬂected signals, the signal reﬂected from the bottom
behind the inserted specimen (tsd) and the signal from the

4Fig. 2. The M-mode and 2-dimensional echocardiograms obtained by the combination method. The target was the aortic valve and the LV
outﬂow tract area. The aortic valve movement was caught for the ﬁrst time by this method in 1965. White arrows on the tomograms show
the ultrasonic beam direction for obtaining the M-mode image.

bottom without the specimen (twd), is obtained from thephase diﬀerence between both signals, which is the resultof analysis in the frequency domain. Thus, the thicknessof the thin tissue below the pulse length and the speedof sound passing through the thin tissue were possible
to measure accurately by a non-contact and non-invasive
method. The value of ultrasonic applications in cardiology
was increased.
C. Macroscopic Tissue Characterization in Cardiology
In 1965, when an excised heart was scanned with thecompound scanner, using 5-MHz focused ultrasound, it
was found that the echogram of the ventricular wall was
rather consistent with the actual cross-section of the walland clearly exhibited the three-layer muscle structure [10]–[12] (Fig. 1). These ﬁndings strongly suggested that noninvasive evaluation of changes in myocardial tissue character in myocardial diseases could be performed.
Since then, Tanaka et al. began investigations of ultrasound tissue characterization. In 1970, as a result of clinical research, Tanaka et al. pointed out that when highquality diagnostic equipment was employed in the clinicalexamination of patients with myocardial damage, such as
cardiomyopathy, myocardial infarction, and so on, intensiﬁed abnormal echoes from the damaged myocardial area
could be frequently detected [30], which they classiﬁed into
three major types as shown in Fig. 4 [35]–[37].
The ﬁrst type is a case with an unusual increment in theintensity of the echo reﬂected from the endocardium. The
second type is a case with a broad and intensiﬁed echo ofFig. 3. Schematic representation of the principle measuring method
for the thickness and speed of sound for a thin tissue specimen.

the endocardium and a speckle echo localized in the inner half of the myocardium adjacent to the endocardium.
The third type has abnormal echoes throughout the myocardium, and the abnormal echoes in the third type wereclassiﬁed into three subtypes of large speckles, mediumsized speckles, and a ﬁne dotted or powder-like pattern as
shown in Fig. 5.
Also, the pattern of the myocardial echo changed during one cardiac cycle. In normal cases, myocardial echoes
appear throughout the myocardium during diastole andbecome localized in an area near the endocardium during

5Fig. 4. Three major types of abnormal echo patterns observed with 2-dimensional echocardiograms of the left ventricular wall in cases withthe myocardial damage. EFE = Endocardial ﬁbroelastosis, COCM = dilated cardiomyopathy, and HCM = hypertrophic cardiomyopathy.
White arrows show the abnormal echo.

systole. The diﬀerences of echo intensity between systoleand diastole are in the range of 5 to 6 dB in normals. On
the contrary, in the case of a damaged myocardium, thepattern of the abnormal myocardial echo shows a small
diﬀerence or almost no diﬀerence between systole and diastole.
On the other hand, a correlation between the echo pattern demonstrated in two-dimensional echocardiogram andactual histological changes of the tissue character were investigated. These showed, for example, that in a case of
the ﬁrst type, a marked degeneration and an incrementof ﬁbrous tissue were found in the endocardium and in

the surviving myocardial tissue around it. In a case withlarge speckle echoes in the myocardium and broad strong
echoes in the endocardium, thick ﬁbrous tissue and focal
degeneration of the myocardium were observed in the endocardium and in its vicinity as shown in Fig. 6.
These facts strongly suggested that the boundaries between the myocardium and the area of degeneration, orof ﬁbrosis, functions as an echo source, and the shape andnet-like structure of the ﬁbrotic tissue or localized degeneration tissue would be changed during the cardiac cycle byaccompanying contraction and extension of the myocardial
ﬁber [37], [38]. Then, to measure quantitatively the inten-

6Fig. 5. Three subtypes of echo patterns of speckle observed in the left ventricular wall. HCM = Hypertrophic cardiomyopathy; HOCM = hypertrophic obstructive cardiomyopathy. White arrows show the abnormal speckle echo.

sity of the abnormal speckle echoes, the sensitivity-gradedtomogram pair method was developed and introduced inclinical tissue characterization [39]. Using this method, theintensity of abnormal speckle echoes were measured incomparison with that of the echo from the normal pericardium. The intensity of the echo reﬂected from the scar
is approximately 20 dB stronger than that from the normal myocardium. The intensity of the echo reﬂected fromthe ﬁbrous tissue is about 5 to 10 dB stronger than thatfrom the normal myocardium [37], [38], [40].
These ﬁndings showed that the increment of abnormal
tissue produces an increase in the intensity of the abnormal tissue echoes in myocardium and that the grade ofpathological ﬁbrotic change in myocardium is possible toestimate non-invasively by using this method in echocardiography [38].
D. Microscopic Tissue Characterization in Cardiology
To develop an understanding of the occurrence of theabnormal echoes and to be able to identify the abnormal
tissue in the myocardium on the echocardiogram with accuracy, it was necessary to characterize the normal and abnormal myocardial tissue ultrasonically at the microscopic
level. The scanning acoustic microscope (SAM) for the
purpose of biomedical application was developed in 1982[41]; the second one was developed in 1985 at Tanaka’s laboratory in collaboration with N. Chubachi (Tohoku Univ.
and the HONDA Elect. Co. Ltd.) [38], [42].

7Fig. 6. 2-dimensional echocardiograms of long axis cross-sections of the left ventricle for a case of hypertrophic cardomyopathy and actual
cross-section of the ventricle in the same patient taken at autopsy. Histological samples were stained by the Elastica Masson’s trichrom
stain. The blue area shows the ﬁbrotic tissue.

The diameter of the transducer was about 1.6 mm, and100- to 200-MHz ultrasound converged through an acoustic lens. The resolution was of the order of 8 µm. The
rate of attenuation and the velocity of ultrasound thattraveled through the 10-m specimen were quantitatively
measured from the two-dimensional pattern displayed ona color CRT by using a two-dimensional high speed scan,
the so-called C-scan technique.
The following results were made clear. The velocity
of ultrasound in normal myocardium ranges from about
1580 m/s to 1650 m/s. The sound velocity in ischemic tissue of myocardium is slower, and that in the scar tissue
faster, than that in the intact myocardium (Fig. 7). Note
that, the reﬂected power at the boundary between the intact myocardium and scar, or ﬁbrous tissue, were calculated from data obtained by using the acoustic microscopic
method and compared with the echo intensity obtained in
the clinical examination. The values of level diﬀerences inreﬂected power are in good agreement with that of the echo
intensity. These results indicated that the boundary between the ﬁbrous tissue and the intact myocardium serves
as the echo source. The changes in echo pattern during
one cardiac cycle show that the size and spatial arrangement of the boundary between the area of abnormal tissues and normal ones change to a certain extent [37]. It
was concluded that the changes of the tissue character,such as degenerative change, ﬁbrotic change, scar, etc.,
can be evaluated non-invasively by using two-dimensional

echocardiography [38]. The possibility of tissue characterization by echo method has also been conﬁrmed by themethod of integrated backscatts [43]–[47].
V. Development of Ultrasonic Technology for
Obtaining Information on Cardiac Function
The heart is a sacciform organ composed of myocardial ﬁber and functions as a mechanical hydraulic pumpfor driving the blood through all parts of the body. Whenperforming the pump function, changes in length of myocardium in the ﬁber direction, caused by contraction or
extension, produces displacement of the chamber wall inthe direction perpendicular to the ﬁber orientation as wellas the changes in thickness of the wall. The perpendicular displacement of the wall produces changes in shape,size, and volume of the cardiac chambers. In other words,
the force generated by contraction or extension of the
myocardium in the ﬁber direction is converted into force
in the direction perpendicular to the ﬁber by changes inshape and size of the chamber, and this is transmitted tothe intracavitary blood. Thus, the blood pressure in thechambers is made to increase in the contraction phase or
decrease in the extension phase. The quantity of blood,equal to the volume diﬀerence generated by changing theshape and size of the cardiac chambers during the cardiac
cycle, is pumped out through the arterial system. Therefore, for the purpose of assessment of cardiac function in

8Fig. 7. Acoustical and optical microscopic images of an infarcted myocardium taken from the left ventricular wall in a case with myocardial
infarction. In the optical image, the specimen was treated with the Masson’s trichrom stain. In the acoustical image, red shows the highspeed area, and blue shows low speed area. The intact myocardium is shown in yellow. Ultrasonic frequency used was 130 MHz.

much more detail in the clinic, the following two kinds offunctions should be measured in practice: 1) myocardial
function, which is the fundamental function of the wall
structure of the heart; and 2) hydraulic pump function,
which is representative as the deformability of the cardiac
structures, changes in the local ﬂow volume and pressure,and their interrelationships during cardiac pulsation.
A. Application of Ultrasound to Measure
Myocardial Function
The most common measurements employed to estimate
myocardial function are the changes in dimensions of theventricular wall, such as the displacements of the length ofthe chamber wall along the longitudinal direction, changes
in the circumferential length of the wall at an arbitrary
part of the chamber, and changes in velocity and direction of the movement of the wall and the contractile
force of a muscle. For this purpose, M-mode echocardiography and two-dimensional echocardiography have been
employed frequently. Furthermore, several kinds of application methods mentioned subsequently have been developed by Tanaka et al.
1) Combination Method Using M-Mode Echocardiography and Ultra-Sono-Cardiotomography (1966) [11], [12](Fig. 2): By using this combination method, the target
portion of the cardiac structures to be measured can beeasily and precisely conﬁrmed on the cross-section pictureof the heart. Moreover, velocity and direction of movements and the magnitude of the displacement of the target
portion occurring during the cardiac cycle were measured
accurately [48], [49].
2) Ultrasono-Tomokymography (1968) [50] (Fig. 8): By
performing the ultrasonic sector scan at a very slow ultrasono-cardiotomography (two-dimensional echocardiography) speed, the image obtained is a two-dimensional
echocardiogram on which the amplitude of the motion ofvarious heart structures during the cardiac cycle are superimposed. Accordingly, intuitive observation and measurement of the motion of cardiac structures and of thedeformability of the chamber wall can be obtained. Recently this method has been improved as the kinetic imaging method.
3) Development of the Simultaneous Multi-Recording
System of M-Mode Echocardiogram, Doppler Echocardiogram, ECG, Phono Cardiogram (PCG), Mechano Cardiogram (MCG), and Pressure Tracing (1970) [51] (Fig. 9):
In this system, by using a thermal recording system, theM-mode echocardiogram, and Doppler ﬂow velocity data,
it became possible to record these continuously together
with physiological data such as ECG, PCG, MCG, andpressure tracing. The interrelationships among the changes
in dimension, electrical events, mechanical events, and hydrodynamic events occurring during the cardiac cycle orduring disease processes became possible to analyze in de-

9Fig. 8. Ultrasono-tomokymogram (right) and ultrasono-cardio-tomogram (left) for normal hearts.

tail, and following the global functioning of the heart became available [49], [52]–[56].
4) Measurement of the Local Myocardial Function by
Development of the Phase Diﬀerence Tracking Method(1996) [57] (Fig. 10): For an accurate understanding andestimation of myocardial function (contractility and extensibility) at an arbitrary position in the heart wall, it
is necessary to measure changes in thickness of the local
myocardial ﬁber, which is an element of the myocardiam,because the thickness of the myocardial ﬁber increases
in the systolic phase by contraction of the ﬁber and decreases in the diastolic phase by relaxation of the ﬁber.
However, in the living state, it is diﬃcult to measure thechanges in thickness of each myocardial ﬁber because of alack of the suitable practical measuring method. Furthermore, the changes in thickness of the ﬁber are very small(< 10 µm) and are always overlapped with about 10-mmmovement of the heart wall, which occurs during one cardiac cycle. Accordingly, for accurate measurement of the
myocardial function, the thickness changes of the ﬁber of< 10 µm have to be measured separately by developing a
new method for accurately tracking the large movement of
the heart wall.
In 1996, Kanai (Tohoku University) and Tanaka developed and proposed [58], [59] a new method of the “phase
diﬀerence tracking method” [57] by using the digital dataprocessing technique. In this method, ultrasonic pulse reﬂection technique is used basically. The phase diﬀerence
between two successive ultrasonic pulses reﬂected from apoint set arbitrarily in the heart wall is measured. By multiplying the phase diﬀerence thus obtained and the velocity
of ultrasound in the myocardium, which is approximately
1540 m/s, the moving velocity of the point set in the heart
wall that occurred during the time interval between two
successive pulses is obtained. Subsequently, when the time
integration of the moving velocity during the pulse repe-

tition period is performed, the displacement of the pointthat occurred during the time interval between two successive pulses is obtained. When the displacement of thepoint is continuously calculated and recorded using thevelocity data obtained from the phase diﬀerence between
two successive pulse echo signals during one cardiac cycle, the movement of the point in the heart wall including
the small amplitude (< 10 µm), which occurred because ofchanges in thickness of the myocardial ﬁber, is successfully
detected.
On the other hand, when this method is applied to multiple points preset at about every 0.75 mm, i.e., limitedwith the sampling rate of the A/D converter, in the heart
wall along the ultrasonic beam, the spatial distribution of
the velocity at these points is obtained simultaneously; themaximum velocity measured is about 0.58 m/s. Then, because of continuous recording of the displacement of eachpoint during the cardiac cycle and the obtaining of differences in the displacement between successive pairs of
points, changes in the myocardial layer width thickening
can be estimated, as shown in Fig. 10. From knowledgeof the layer thickening, regional myocardial functioning,such as strain, strain energy, and movability (contractility
and/or extensibility), of the local myocardial ﬁber could
be estimated non-invasively and precisely clinically [60].
B. Application of Ultrasound to Measure theHydraulic Pump Function of the Heart
The pump function is represented as deformability. Deformability is the capability to make changes in the shapeof the heart chamber and the position and conﬁguration of
structures such as valve leaﬂets, chorda tendinea, papillarymuscles, chamber wall, etc. Deformability of the heart isaﬀected by the direction and magnitude of the force produced at each local area of the chamber wall and plays
an important role to making blood move into and out of

10

Fig. 9. An example of the record obtained by using the multi-recording system developed in 1970.

the cardiac chambers. It is considered that deformability
is reﬂected on the ﬂowing state of the intracavitary bloodand on the pressure distributions in the heart chambers.
Therefore, for practically assessing the pump function inmuch more detail, deformability of the heart should bemeasured clinically.
For this purpose, it is indispensable to measure and to
estimate not only the size, shape, and displacement of theheart structures and their interrelationships during cardiac
cycle or disease processes, but also the hydrodynamic information such as the ﬂowing state (laminar or turbulent),
the moving direction and ﬂowing volume of the blood at
the local portion in heart chambers, pressure diﬀerences
between the local parts in the same chamber, and twoor three-dimensional pressure distribution in the cardiac
chambers. At the initial stage, Tanaka et al. developed the
biplane cardiotomographic method with high speed mechanical scanning in 1978 [61]. For visualizing the intraventricular blood ﬂow, the contrast method in the twodimensional echocardiography using the saline injection
technique via cardiac catheterization was also done in 1978
[62].
However, it was considered that the ultrasonic Doppler
method was adequate as a method for the collection of hydrodynamic data of intracardiac blood ﬂow, because accurate velocity data could be obtained without disturbanceof the blood ﬂow process, as compared, for example, with
the insertion of a transducer. Moreover, if an appropriatetechnique of velocity data processing were to be developed,
the hydrodynamic data for clinical evaluation of the pumpfunction could be deduced non-invasively.
Then, Tanaka, Ohtsuki (Tokyo Institute of Technology),
and their colleagues began to develop the transthoracic

technique for the ultrasonic Doppler method, which could
be applied to detect ﬂow velocity of the intracardiac blood.
1. Development of the Ultrasonic Doppler Method with
Depth Resolution: In 1967, Okujima and Ohtsuki [63], [64]began development of a new ultrasonic Doppler ﬂow metersystem with depth resolution. At that time, many investigators used continuous wave ultrasonic Doppler methods
for the detection of blood ﬂow velocity in peripheral vessels[1], [3], [14], [66], [67].
At the beginning of this investigation, the ultrasonicpulsed Doppler equipment made in our laboratory could
not be used for detection of intracardiac blood ﬂow velocity because of insuﬃcient gain in the ampliﬁer and poor
SNR [63], [64]. Development and clinical application of the“M-sequence modulated ultrasonic Doppler method” wasaccomplished at that time (1970), which made it possible
for the blood ﬂow velocity data in the heart chamber inliving state to be obtained non-invasively, as illustrated inFig. 11 [65].
In 1975, the multichannel Doppler system was developed [66], [67] in which real time analysis of the Doppler
signals received was realized by introducing the heterodyne
analyzing method. Moreover, the Doppler method andtwo-dimensional echocardiography were used in combination such that an arbitrary target space within the heart
could be selected, with reference to the two-dimensional
echocardiogram, and the blood ﬂow velocity data at thetarget point and velocity proﬁle along the beam direction for a distance of about 12 cm could be detected inreal time. Fig. 12 shows an instantaneous velocity proﬁledisplay of the intracardiac blood ﬂow in the rapid ﬁllingphase in a normal subject. The thick arrows on the twodimensional echocardiogram indicate the beam direction.

11

Fig. 10. Changes in thickness moving speed of the regional myocardium in the ventricular septum in a normal case measured by the phase
diﬀerence tracking method. The distance between two adjacent points is about 0.75 mm. Color distribution shows the normalized speed ofchange in thickness. Blue indicates +5 m2 /s, and yellow indicates −5 m2 /s. Upper panel: Superimposed display with M-mode and thickness
change and normalized speed change in thickness. Lower panel: Thickness change. Middle panel: Overlapped display of the speed of whole
points. A = Atrial contraction, IC = isometric contraction, E = ejection, ID = isometric dilatation, R = rapid ﬁlling, and S = slow ﬁlling.

Then, if the ﬂow velocity proﬁle along the beam axis was
obtained by changing the beam direction on the scanningplane at the same cardiac phase, the two-dimensional velocity distribution at an arbitrary cardiac phase could beobtained by special interpolation between two adjacent velocity proﬁles and displayed as a color coded pattern [72].
In 1980, a new ultrasonic pulsed Doppler technology
was developed that could measure the ﬂow velocity at anarbitrary portion of the heart chamber [70], [71]. Doppler
signals recorded at multiple sampling points on the apicallong-axis section plane are analyzed with the FFT method
in real time [73].

2. Development of the Data Processing Technique for
Detecting Hydrodynamic Information from Doppler Velocity Data: The important parameters for hydrodynamic information for estimating the pump function are ﬂow volume, pressure, and their changes during the cardiac cycle. Furthermore, from the clinical point of view, it is themost convenient for an intuitive evaluation of cardiac function, provided that the hydrodynamic information is represented as a two-dimensional distribution image on theultrasonic scanning plane.
Since 1982, Tanaka et al. have been developing the following two new data processing techniques based on hydro-

12Fig. 11. Intraventricular blood ﬂow velocity pattern obtained from a case of aortic insuﬃciency by the M-sequence modulated ultrasonic
Doppler method combined with the ultrasono-cardiotomography in 1970. Flow velocity data were detected at the white areas (1 ∼ 7)
indicated on the tomographic image and analyzed with a sonagraph. In the diastolic phase, regurgitant velocity patterns with high frequency
harmonics are represented.

dynamics, i.e., two-dimensional distribution of blood ﬂow
volume on the ultrasonic scanning plane [74]–[77] and twodimensional distribution of dynamic pressure and pressure
diﬀerences on the scanning plane [78], [79].
3. Two Dimensional Distribution of Blood Flow Volume
on the Scanning Plane: For this purpose, displaying thestream line distribution is most appropriate for intuitive
understanding of local and whole blood ﬂow volume andﬂow state in the heart chamber on one scanning plane.
This is because the stream line represents the direction of
the velocity vector of the ﬂow and the interval between two
adjacent stream lines represents the ﬂow volume [80]–[82].

The velocity data obtained at a point on the ultrasonicbeam by the ultrasonic Doppler ﬂow meter system withdepth resolution are divided into two components, namely
the Uz component in the X-Z plane and the Uy component
in the X-Y plane. The Uz component is concerned with intersecting ﬂow, and the Uy component is concerned withﬂow parallel to the scanning plane. Accordingly, the twodimensional distribution of the Doppler velocity on the ultrasonic scanning plane is also contained on the two velocity components, because the blood ﬂow in the heart chambers is spatially three-dimensional. To obtain the streamline distribution on the scanning plane, it is necessary to13

Fig. 12. Instantaneous velocity proﬁles of the intracardiac blood ﬂow during diastole (phase shown by a white dot on the ECG), which wereobtained in the left ventricle in a normal case in the various beam directions (1 ∼ 5). Beam directions were conﬁrmed by the ultrasonocardiotomogram that was simultaneously recorded.

give consideration to these two ﬂow components. Ohtsuki
and Tanaka developed a new concept on the ﬂow function
theory in 1997 [83], which established the method for obtaining the stream line distribution on an arbitrary section
plane in three-dimensional ﬂow, allowing the characteristics of the ﬂow to be visualized and evaluated.
The ﬂow function [Q(X, Y )] consists of two kinds offunctions. One is the boundary function [Qb (X, Y )], whichis considered to exist at the source of inﬂow (Si) and outﬂow (So) and is positioned at the boundary of the observing plane (scanning plane); the ﬂow appears parallel to the plane and is called two-dimensional ﬂow. The
boundary function is the same as the stream function in
two-dimensional ﬂow. The other is the fundamental ﬂow
function or the laminary ﬂow function [Qp (X, Y )], whichis considered to be at the Si or the So from the scanningplane and is at the point source dispersed on the observing

plane with the ﬂow appearing perpendicular to the plane.
The Si represents a positive source and is shown on theobserving plane as a green-colored point. The So represents a negative source, or a sink, and is shown as a pinkcolored point. The ﬂow function [Q(X, Y )] is represented
as Q (X, Y ) = Qb (X, Y ) + Qp (X, Y ).
Accordingly, from the data thus obtained by both calculation of the boundary function and the fundamental
ﬂow function, the ﬂow function is calculated, and equiﬂow function lines are drawn at each interval of the unit
ﬂow volume, corresponding to the quantized step, yielding
the stream line distribution, which begins at the positive
source and ends at the negative source.
Fig. 13 shows the two-dimensional distribution of thestream lines in systole obtained from a normally functioning case (upper pictures) and an infarction case (lower
pictures). The pictures on the left were taken during the

14

Fig. 13. 2-dimensional distribution images of the stream lines in normal (upper panel) and myocardial infarction (lower panel). Stream line
begins at the positive source (green-colored dot) and ends at the negative source (pink-colored dot). Flow state and local ﬂow volume werequite diﬀerent between normal and infarction.

15

isometric contraction (IC) phase, and the picture on theright was taken during the early systolic phase. The streamlines in the outﬂow area show a relatively smooth pattern,although the circular pattern is observed at the posterobasal area of the ventricle in IC. The ﬁgures show a circular or a semicircular pattern of the stream lines at
the apical area of the left ventricle during systole. The
case of antero-septal myocardial infarction, a ventricularaneurysm (white arrow), is clearly visible in the apicalarea. These ﬁndings show that the circular pattern of thestream line indicates rotating ﬂow and that, in the ventricular aneurysm, abnormal rotating ﬂow appears at the
beginning phase of systole. From the stream line distribution thus obtained, ﬂow direction, ﬂow volume at the local
area, and the characteristics of three-dimensional ﬂow canbe evaluated visually and quantitatively.
The interval between two adjacent stream lines indicates ﬂow volume in cm2 /s. Thus, one-dimensional ﬂow
volume distributions along the line normal to the streamline indicate a representative ﬂow passing through theshort axis cross-section plane and the integrated value ofthe area of this distribution represents the instantaneous
ﬂow volume passing through the short axis cross-section of
the ventricle during a particular cardiac phase (Fig. 14).
Provided that the instantaneous ﬂow volume, mentioned previously, is recorded continuously during one cardiac cycle, the ﬂow volume, which is equivalent to thestroke volume or cardiac output, and the ﬂow volume curve
during one cardiac cycle are obtained as shown in Fig. 15.
When the diﬀerence in ﬂow volume between two time
points is obtained, that diﬀerence indicates the work in
displacing the blood from the ventricle, the portion below the selected short axis-cross section plane, as shownin Fig. 14. When a diﬀerence in ﬂow volume is obtained
between two diﬀerent cross-sectional planes at the sametime, that diﬀerence determines the deformability of thelimited portion of the ventricle existing between the twocross-sectional planes, as shown by the diﬀerences between
two adjacent ﬂow volume curves in Fig. 15.
As understood from these results, much useful information regarding pump function became known as pumpfunction index, for example, cardiac output, stroke volume at various portions of the ventricle, work, ﬂow rate,ejection rate, ejection loss, energy loss, etc., as well as information regarding the ﬂow state, acceleration rate, andhydrodynamic data [84]–[86].
VI. Two-Dimensional Distribution of Dynamic
Pressure and Pressure Difference in the
Scanning Plane
When a pressure diﬀerence appears in a ﬂuid, the ﬂuid
moves from the high pressure region to the low pressure
region, and ﬂow occurs. Thus, a close correlation exists
between the velocity of ﬂow and the pressure diﬀerence,as understood from Euler’s equation of motion.
In 1983, Tanaka et al. pointed out the following correlation from the results obtained [87], [88] from physical ex-periments using the narrowing ﬂow model, viz., maximum
velocity  41.3× (pressure diﬀerence)0.57 . These facts
strongly suggested that details of the two-dimensional distribution of pressure and pressure diﬀerences, which are indispensable for producing the ﬂow in the chamber, can beobtained from two-dimensional velocity distribution data
(B-mode Doppler velocity), if the processing technique isadequate for deducing the pressure values from the velocity distribution data.
Since then, in 1986, Tanaka et al. developed a new processing method for visualizing the two-dimensional pressure (dynamic pressure) distribution on the scanning plane
and the one-dimensional pressure distribution along theline set on the cross-sectional view of the heart [78], [79].
By using the two-dimensional distribution of the velocity component (u) measured by the pulse Doppler method,the velocity component (v) orthogonal to the beam direction is deduced by applying the ﬂow function theory [78],[81], [82]. Thus, the B-mode Doppler acceleration (Adb ),which is calculated by using the velocity components ofthe two-dimensional velocity distribution on the scanningplane, can be obtained based on the Euler’s equation of
motion:
Dv
= Adb
Dt
−∇p = ρ · Adb
where v is the deduced average velocity vector on the scanning plane, ρ is density of the medium, and p is pressure.
From linear integration performed along the line connecting the reference point to the observation point on theplane, i,e.,
p = −ρ Adb×d1
1

the Doppler pressure and the velocity on the scanningplane can be deduced from the Euler’s equation of motion as

 
∂v
P d = P r ef + ρ+ (v × v ) ds∂tl
where l is length of the path, ds is unit area in the scanningplane, and Pref is the pressure at the reference point on
the plane. Although Pd thus calculated is a multi-valued
function that depends on the path, the equi-pressure lines
can be obtained in the same manner as that in the ﬂow
function. Thus, the Doppler pressure distribution on thescanning plane can be decided from the two-dimensional
velocity distribution data on the scanning plane set in themoving ﬂuid in three dimensions [89]–[92].
In practice, the two-dimensional distribution of theequi-pressure lines overlaps the B-mode echo image, andquantitative pressure distributions along the line, which is
set arbitrarily on the B-mode image, are used.
The Doppler pressure thus obtained is diﬀerent fromthe pressure measured by cardiac catheterization, which

16

Fig. 14. Right-side patterns in the upper picture show the 1-dimensional ﬂow volume distribution at a particular systolic phase along thearbitrary three lines drawn on the 2-dimensional stream line distribution (left side). The 1-dimensional ﬂow volume thus obtained indicatesthe representative ﬂow volume passing through the short axis plane such as Fo and Fi in the lower schemetic picture. The A-B line on the
Sc corresponds with the white line on the 2-dimensional echogram.

17

Fig. 15. Flow volume change at three positions [1 to 3 portion; apex (fa ), center (fc ), and base (fb ) on the tomogram] in the left ventricle
during one cardiac cycle. The length of the bar graphs shows the ﬂow volumes at the particular cardiac phases. Right upper bar graphs
indicate the changes in the ﬂow volume at the various cardiac phases during three cardiac cycles. The three lines of the bar graph wereobtained along every three white lines on the tomogram. Lower curves show the ﬂow volume curves obtained from the envelope of the bar
graph at the three portions.

18

Fig. 16. 2-dimensional Doppler pressure distributions at two cardiac phases in systole obtained from a normal subject. The pressure value
is represented by equipressure lines. Intervals between two adjacent pressure lines are 0.3-mm Hg step. The maximum pressure diﬀerencein each cardiac phase is shown at the left lower corner by the number. The red-colored area shows relatively higher pressure area, and theblue-colored area shows the lower pressure area. The green line indicates the standard level (0 level).

Fig. 17. 2-dimensional Doppler pressure distributions at two cardiac phases in diastole in a normal case.

19

Fig. 18. 1-dimensional pressure distributions along the line of the outﬂow tract (upper left) and along the line of the short axis of theventricle (lower left) at the ejection phase in a normal case.

is total pressure, and is nearly the same as the dynamic
pressure, viz, the pressure required for the displacementof the blood from one point to another. Accordingly, itreﬂects the manner in which the force generated by contraction and extension of the regional myocardium actson the blood, and it can be said that the changes in the
Doppler pressure pattern during the cardiac cycle represent the deformability function of the ventricle.
Fig. 16 is an example of the two-dimensional Doppler
pressure distribution during the IC and in late systole fora normal case, and Fig. 17 is that for isometric dilatation
and rapid ﬁlling phases. Fig. 18 shows the one-dimensionalpressure distribution along the outﬂow tract (left upper
picture) and that along the short axis of the ventricle (leftlower picture) during systole for a normal heart. Fromthese facts, it can be said that changes of the pressure
distribution pattern during pulsation clearly indicate thedeformability of the ventricle.
There are still many problems that must be solved, e.g.,
the hydrodynamics of blood ﬂow in the heart chambers.
However, it is expected that the methods mentioned previously will become indispensable for accurate, timely clinical cardiology diagnostics.

VII. Conclusion
In this paper, the progression of the developments of theultrasonic application for visualizing and measuring thestructure and function of the heart in our laboratory since1960 has been described. Our projects surrounding ultrasonic application in cardiology were performed systematically in close collaboration with engineering and medicalgroups and also with Japanese and USA staﬀs internationally for about 40 yrs. The author would like to thankespecially F. Dunn, (University of Illinois) for close collaboration and instruction. At this time, it can be said thatthe application of ultrasound to cardiology is certainly progressing. Until now, ultrasound has been chieﬂy applied toevaluate and measure the mechanical events in cardiology.
However, there still remain many other functions in the
cardiovascular ﬁeld to be evaluated visually other than themechanical events, e.g., biochemical events, a new frontier
to be studied.
References[1] D. L. King, Diagnostic Ultrasound. Saint Louis, MO: The C. V
. Mosby Co., 1974.
[2] H. Feigenbaum, Echocardiography. 2nd ed. Philadelphia: Lea &Febiger, 1976.

20[3] R. Gramiak and R. C. Waag, Cardiac Ultrasound. Saint Louis:
The C. V. Mosby Co., 1975.
[4] R. S. Reneman, Cardiovascular Application of Ultrasound. Amsterdam: North-Holland Publ. Co., 1974.
[5] M. Tanaka, Ultrasonic Diagnosis of the Heart. Tokyo: Medical
Electro Times Ltd., 1978, (in Japanese).
[6] Y. Kikuchi, R. Uchida, K. Tanaka, and T. Wagai, “Early cancer
diagnosis through ultrasonics,” J. Acoust. Soc. Amer., vol. 29,
pp. 824–833, 1957.
[7] I. Edler and C. H. Hertz, “The use of ultrasonic reﬂectoscope for the continuous recording of the movements of heart
walls,” Kungl. Fysiogr. Sällsk., i Lund Förhandl., vol. 24, no. 5,
pp. 1–19, 1954.
[8] S. Satomura, “Ultrasonic Doppler method for the inspection ofcardiac functions,” J. Acoust. Soc. Amer., vol. 29, pp. 1181–
1185, 1957.
[9] T. Yoshida, M. Mori, and Y. Nimura, “Studies on the examination of the heart with the ultrasonic Doppler method: Clinicalapplication,” Jpn. Circul. J., vol. 20, p. 228, 1956, (abstract).
[10] T. Ebina, M. Tanaka, Y. Kikuchi, R. Uchida, and S. Kosaka,“Ultrasono-cardio-tomography,” in Proc. Jpn. Soc. Ultrason.
Med., 1964, pp. 49–50.
[11] T. Ebina, M. Tanaka, Y. Kikuchi, S. Oka, S. Kosaka, R. Uchida,
and Y. Hagiwara, “The diagnostic application of ultrasound to
the diseases in mediastinal organs. Ultrasono-tomography for theheart and great vessels,” Sci. Rep. Res. Inst., Tohoku Univ., C,
12(1), pp. 58–74, 1965.
[12] M. Tanaka, T. Ebina, Y. Kikuchi, S. Oka, S. Kosaka, R. Uchida,
and Y. Hagiwara, “Ultrasono-tomo-graphy for the heart, great
vessels and other mediastinal organs,” in Proc. 6th ICME & BE,
1965, pp. 294–295.
[13] D. L. King, “Cardiac ultrasonography, a stop action techniquefor imaging intracardiac anatomy,” Radiology, vol. 103, pp. 387–
392, 1972.
[14] N. Bom, New Concepts in Echocardiography. Leiden: H. E. Stenfert Kroese N.V., 1972.
[15] F. Dunn and W. J. Fry, “Ultrasonic absorption and reﬂection bylung tissue,” Phys. Med. Biol., vol. 5, no. 4, pp. 401–410, 1961.
[16] M. Tanaka, T. Ebina, Y. Kikuchi, S. Oka, S. Kosaka, R. Uchida,
and Y. Hagiwara, “Application of the concave radiator to theultrasonic reﬂection technique,” Proc. JSUM, vol. 7, pp. 59–60,
May 1965.
[17] M. Tanaka and Y. Kikuchi, “Favorable eﬀects of a concave transducer on the ultrasono-tomogram,” Jpn. J. Med. Elect. Biol.
Eng., vol. 5, no. 5, pp. 352–363, 1967, (in Japanese).
[18] Y. Torikai, “Sound ﬁeld near the sound source: Spherical concave sound source,” The Institute of Electronics and Communication Engineers of Japan, Technical Report of Expert Committee in Ultrasonics, (IECE Ultrasonics, Tech. Rep.,), Oct. 1955,(in Japanese).
[19] Y. Torikai, “Near ﬁeld and far ﬁeld of ultrasound,” IECE Ultrasonics, Tech. Rep., Sep. 1960, (in Japanese).
[20] Y. Torikai, “Calculation on the near ﬁled ultrasound,” IECE
Ultrasonics, Tech. Rep., Nov. 1962, (in Japanese).
[21] S. Ohtsuki and M. Okujima, “Calculation of the near ﬁeld ultrasound irradiated from the semicircular transducer,” IECE Ultrasonics, Tech. Rep. US71-47, Mar. 1972, (in Japanese).
[22] T. Ebina, M. Tanaka, S. Oka, Y. Kikuchi, S. Kosaka, R. Uchida,
and Y. Hagiwara, “The diagnostic application of ultrasound to
the disease in mediastinal organs,” Tohoku Univ.-C, Sci. Rep.
Res. Inst. vol. 12, pp. 199–212, 1965.
[23] M. Tanaka, Y. Kikuchi, T. Ebina, S. Kosaka, S. Oka, Y. Terasawa, K. Unno, D. Okuyama, R. Uchida, and Y. Hagiwara,“Ultrasono- cardio-tomo-graphy (7th report); Improvement inquality of the tomographic pattern by applying a STC device,” Med. Ultrason., vol. 5, no. 1–2, pp. 49–50, 1967.
[24] M. Tanaka, Y. Kikuchi, T. Ebina, S. Oka, S. Kosaka, Y. Terasawa, D. Okuyama, C. Kasai, K. Unno, and R. Uchida, “Eﬀects
of the FT C circuit on the ultrasono-tomography,” Med. Ultrason., vol. 6, no. 2, pp. 131–132, 1967.
[25] M. Tanaka, Y. Terasawa, K. Giga, S. Hirafuku, Y. Hagiwara, and S. Shigeyama, “Small sized high speed mechanicalultrasono-cardiotomography,” in Proc. JSUM, vol. 32, pp. 49–
50, Nov. 1977.
[26] M. Tanaka, S. Kosaka, S. Oka, Y. Kikuchi, T. Ebina, Y. Terasawa, K. Unno, R. Uchida, and Y. Hagiwara, “Automatic control

method synchronized with cardiac pulsation for ultrasonic diagnostic equipment,” Kokenshi, vol. 20, no. 3, pp. 291–312, 1968,(in Japanese)..
[27] M. Tanaka, S. Oka, T. Ebina, Y. Kikuchi, S. Kosaka, Y. Terasawa, K. Unno, R. Uchida, and Y. Hagiwara, “Diagnostic application of ultrasound to diseases in mediastinal organs: The
ultrasono- tomography in living human subjects,” Tohoku Univ.
C., Sci. Rep. Res. Inst., vol. 14, no. 1–2, pp. 1–21, 1967.
[28] M. Tanaka, S. Oka, T. Ebina, Y. Kikuchi, S. Kosaka, Y. Terasawa, K. Unno, D. Okuyama, R. Uchida, and Y. Hagiwara,“Analysis of the mechanical movement of the left cardiac portions by means of the ultrasono-cardio- tomography,” Med. Ultrason., vol. 5, no. 1–2, pp. 42–43, 1967.
[29] M. Tanaka, S. Kosaka, S. Oka, Y. Kikuchi, T. Ebina, Y. Terasawa, K. Unno, D. Okuyama, C. Kasai, R. Uchida, and Y. Hagiwara, “Morphological measurement of the heart by ultrasonocardiotomography,” Med. Ultrason., vol. 7, no. 1, pp. 45–46,
1969.
[30] M. Tanaka, T. Neyazaki, S. Kosaka, T. Ebina, S. Oka, H. Sugi,
K. Unno, Y. Terasawa, and K. Nitta, “Ultrasonic evaluation of
anatomical abnormalities of heart in congenital and acquired
disease,” Br. Heart J., vol. 33, pp. 686–698, 1971.
[31] H. Okawai, M. Tanaka, S. Nitta, and F. Dunn, “In vivo measurement of thickness or of speed of sound in biological tissue
structures,” IEEE Trans. Sonics Ultrason., vol. SU-30, no. 4,
pp. 231–237, 1983.
[32] M. Tanaka, H. Okawai, S. Otsuki, H. Hachiya, and F. Dunn,“Non-contact, measurement of the acoustic characteristics of thebiological tissues by the frequency shifting method,” in Rep.
Basic Technol. Comm. JSUM, vol. 90, no. 5, pp. 29–32, 1990,(in Japanese).
[33] H. Hachiya, T. Saito, S. Ohtsuki, and M. Tanaka, “High accuracy non-contact speed measurement of the biological tissues bymeans of the frequency analysis of the ultrasonic pulse response
signals,” J. J. Med. Ultrason., vol. 17, Suppl. II, pp. 347–348,
Oct. 1990, (in Japanese).
[34] H. Hachiya, S. Ohtsuki, M. Tanaka, and F. Dunn, “Determination of sound speed in biological tissues based on frequency
analysis of pulse response,” J. Acoust. Soc. Amer., vol. 92, no.
3, pp. 1564–1568, 1992.
[35] M. Tanaka, “Quantitative evaluation of the myocardial damage
by the ultrasono-cardiotomography,” Myakuha, vol. 5, no. 2, pp.
196–202, 1975, (in Japanese).
[36] M. Tanaka and Y. Terasawa, “Evaluation of the tissue characterin myocardium,” Jpn. Circul. J., vol. 43, no. 4, pp. 367–376,
1979.
[37] M. Tanaka, S. Nitta, Y. Sogo, A. Yamamoto, K. Nitta, Y.
Katahira, N. Sato, H. Ohkawai, and F. Tezuka, “Non-invasive
estimation by cross sectional echocardiography of myocardialdamage in cardiomyopathy,” Br. Heart J., vol. 53, pp. 137–152,
1985.
[38] M. Tanaka and F. Dunn, “Acoustic properties of the ﬁbrous tissue in myocardium and detectability of the ﬁbrous tissue by theecho method,” in Ultrasonic Tissue Characterization. F. Dunn,
Ed. Tokyo: Springer-Verlag, 1996, pp. 231–243.
[39] M. Tanaka, “Diagnostic application of the sensitivity-gradedtomogram pair method to the diagnosis of the cardio-vasculardiseases,” J. Med. Ultrason., vol. 3, no. 1, pp. 11–18, 1976, (inJapanese).
[40] M. Tanaka, “Ultrasono-cardiotomography and its clinical effects,” J. Adult Dis., vol. 7, no. 10, pp. 1677–1685, 1977, (inJapanese).
[41] M. Tanaka, H. Okawai, N. Chubachi, J. Kushibiki, S. Nitta,
K. Nitta, Y. Sogo, A. Yamamoto, N. Sato, and T. Sannomiya,“Quantitative measurement of the acoustic properties of the biological tissue; Acoustic microscopic examination,” Proc. JSUM,
vol. 43, pp. 585–586, Dec. 1983, (in Japanese).
[42] M. Tanaka, H. Okawai, N. Chubachi, J. Kushibiki, and T. Sannomiya, “Development of the acoustic microscope Type 3,” inProc. JSUM, vol. 45, pp. 677–678, Oct. 1984, (in Japanese).
[43] D. Bauwens, M. O’Donnell, J. G. Miller, B. E. Sobel, and J. W.
Mimbs, “Quantitative alterations in ultrasonic backscatter inischemic myocardium induced with collagenase,” Clin. Res., vol.
27, p. 152-A, 1979, (abstract).
[44] M. O’Donnell, D. Bauwens, J. W. Mimbs, and J. G. Miller, “Integrated ultrasonic backscatter as an approach to tissue charac-

21
terization in vivo,” IEEE Trans. Sonics Ultrason., vol. SU-27,
p. 147, 1980, (abstract).
[45] M. O’Donnell, J. W. Mimbs, and J. G. Miller, “The relationship between collagen and ultrasonic backscatter in myocardial
tissue,” J. Acoust. Soc. Amer., vol. 69, pp. 580–588, 1981.
[46] J. W. Mimbs, D. Bauwens, R. D. Cohen, M. O’Donnell, J. G.
Miller, and B. E. Sobel, “Eﬀects of myocardial ischemia on an
quantitative ultrasonic backscatter and identiﬁcation of responsible determinants,” Circul. Res., vol. 49, pp. 89–96, 1981.
[47] J. G. Miller, “Some relationships between echocardiography,
quantitative ultrasonic imaging and myocardial tissue characterization,” in Ultrasonic Tissue Characterization. F. Dunn, Ed.
New York: Springer-Verlag, 1996, pp. 139–167.
[48] M. Tanaka, “Acquired heart disease-Clinical usefulness of thecomplex ultrasonic examination,” J. Med. Ultrason., vol. 4, no.
2, pp. 75–83, 1977, (in Japanese).
[49] M. Tanaka, “Echocardiogram,” Internal Med., vol. 36, no. 5, pp.
724–734, 1975, (in Japanese).
[50] M. Tanaka, S. Kosaka, Y. Kikuchi, T. Ebina, S. Oka,
Y. Terasawa, K. Unno, D. Okuyama, C. Kasai, and R.
Uchida, “Ultrasono-tomography for the heart and great vessels;
Ultrasono-tomo-kymography,” Med. Ultrason., vol. 7, no. 1, pp.
47–49, 1968.
[51] M. Tanaka and Y. Yoshikawa, “UCG polygraph,” Med Electron.,
vol. 4, pp. 4–6, Jun. 1974, (in Japanese).
[52] M. Tanaka, “Ultrasound cardiography,” Cardioangiology, vol. 2,
pp. 311–318, Oct. 1977, (in Japanese).
[53] M. Tanaka, S. Kosaka, Y. Terasawa, M. Kashiwagi, H. Hikichi,
T. Meguro, K. Watanabe, and H. Takeda, “A signiﬁcance of themitral valve movement to the genesis of the late systolic murmur
in mitral insuﬃciency,” Cardiovascul. Sound Bull., vol. 5, no. 4,
pp. 679–691, 1975.
[54] M. Tanaka, “Ultrasono-cardiotomography-Diagnostic application,” Heart, vol. 5, no. 8, pp. 1151–1162, 1973, (in Japanese).
[55] M. Tanaka, M. Kashiwagi, S. Kosaka, Y. Terasawa, K. Nitta, T.
Meguro, and H. Takeda, “Acoustic characteristics and genesisof the heart murmur in classic form of cor triatriatum,” Cardiovascul. Sound Bull., vol. 4, no. 2, pp. 457–470, 1974.
[56] M. Tanaka, S. Kosaka, Y. Terasawa, K. Unno, K. Nitta, and
M. Kashiwagi, “A new concept concerning the mechanism producing the diastolic musical murmur (Sea-gull cry) in aortic insuﬃciency,” Cardiovascul. Sound Bull., vol. 3, no. 1, pp. 1–12,
1973.
[57] M. Tanaka, K. Nitta, H. Kanai, and N. Chubachi, “A new
method for evaluating the local myocardial function by the phase
diﬀerence tracking technique in echocardiography,” in Proc. 7th
APCDE, 1997, p. 113.
[58] H. Kanai, N. Chubachi, Y. Koiwa, and M. Tanaka, “Non invasive
measurement of motion velocity on heart wall and its application,” in Proc. 3rd Joint Mtg. Acoust. Soc. Amer. Acoust. Soc.
Jpn., 1996, pp. 211–216.
[59] H. Kanai, N. Chubachi, Y. Koiwa, and M. Tanaka, “Non invasive
measurement of speed of thickness change in heart wall and its
color coded imaging,” IEICE, US, Tech. Rep. 96-59, Oct. 1996.
[60] H. Kanai, H. Hasegawa, M. Tanaka, N. Chubachi, and Y. Koiwa,“Non-invasive evaluation of spatial distribution of local instantaneous strain energy in heart wall,” in Acoustic Imaging. vol.
23, S. Lees and L. A. Ferrari, Eds. New York: Plenum Press,
1997, pp. 187–192.
[61] M. Tanaka, Y. Terasawa, M. Okujima, S. Ohtsuki, K. Giga, Y.
Hagiwara, S. Shigeyama, and K. Fujie, “Simultaneous display of
the tomographic images in two diﬀerent directions of the scanning plane in ultrasono-cardiotomography. Bi-plane cardiotomography,” J. Med. Ultrason., vol. 5, no. 2, pp. 103–110, 1978, (inJapanese).
[62] M. Tanaka, T. Meguro, K. Konno, T. Ebina, K. Iinuma, T. Kidokoro, S. Nitta, K. Tabayashi, T. Horiuchi, M. Kashiwagi, K.
Watanabe, H. Hikichi, K. Nitta, H. Takeda, Y. Hagiwara, and
M. Miki, “Contrast cardio-tomography and its clinical signiﬁcance,” J. Med. Ultrason., vol. 5, no. 1, pp. 23–30, 1978, (inJapanese).
[63] M. Okujima and S. Ohtsuki, “Studies on the ultrasonic Doppler
ﬂow meter,” IECE Ultrasonics, US, Tech Rep. 69-38, 1969.
[64] M. Okujima and S. Ohtsuki, “M-sequence-modulated ultrasonic
Doppler ﬂow meter,” IECE Ultrasonics, US, Tech. Rep. 7019, 1970.

[65] M. Tanaka, M. Okujima, S. Ohtsuki, S. Kosaka, S. Oka, Y. Terasawa, K. Unno, K. Nitta, M. Kashiwagi, and T. Ebina, “Thecombination method of ultrasono-cardiotomography and Msequence modulated ultrasonic Doppler method,” Proc. JSUM,
vol. 19, pp. 41–42, May 1971.
[66] J. Kisslo, D. Adams, and D. B. Mark, Eds. Basic Doppler
Echocardiography. New York: Churchill Livingstone, 1986.
[67] L. Hatle and B. Angelsen, Doppler Ultrasound in Cardiology.
Philadelphia: Lea & Febiger, 1982.
[68] M. Tanaka, M. Okujima, S. Ohtsuki, K. Katakura, Y. Terasawa,
K. Nitta, M. Kashiwagi, T. Meguro, K. Watanabe, H. Hikichi,
H. Takeda, K. Konno, T. Ebina, Y. Sato, and K. Tanabe, “Noninvasive measurement of the intracardiac blood velocity and velocity proﬁle by means of the M-sequence modulated ultrasonic
Doppler method,” J. Med. Ultrason., vol. 3, no. 2, pp. 99–109,
1976, (in Japanese).
[69] M. Tanaka, M. Okujima, S. Ohtsuki, Y. Terasawa, K. Konno,
and T. Ebina, “Non-invasive measurement of the blood ﬂow velocity and of velocity distribution in cardiac chamber and great
vessels by a new Doppler ﬂow meter system,” in Ultrasoundin Medicine. 3B, D. White and R. E. Brown, Eds. New York:
Plenum Publ. Co., 1977, pp. 1263–1277.
[70] M. Tanaka, M. Kashiwagi, K. Nitta, K. Namekawa, C. Kasai, T.
Mizoguchi, K. Watanabe, H. Hikichi, and M. Terashima, “Thedevelopment of polygraphic direct recording system of the ultrasonic Doppler cardiogram,” Proc. JSUM, vol. 36, pp. 295–296,
Jun. 1980.
[71] H. Takeda, M. Tanaka, Y. Seo, K. Komatsu, M. Kashiwagi, K.
Nitta, K. Watanabe, H. Hikichi, and H. Sogo, “A clinical evaluation of the single probe ultrasound system of simultaneously
displaying the real time two-dimensional echocardiogram andthe Doppler signal,” Proc. JSUM, vol. 37, pp. 27–28, Oct. 1980.
[72] M. Tanaka, H. Takeda, M. Kashiwagi, M. Okujima, S. Ohtsuki,
K. Nitta, H. Hikichi, and K. Watanabe, “The two dimensional
ﬂow velocity proﬁle system,” Proc. JSME BE, vol. 18, no. 3, pp.
910–911, May 1980.
[73] M. Tanaka, M. Okujima, S. Ohtsuki, R. Uchida, and S.
Shigeyama, “Multichannel recording of the ultrasonic Doppler
signal of the blood ﬂow in cardiac chamber,” Proc. JSUM, vol.
26, pp. 159–160, Oct. 1974.
[74] S. Ohtsuki, M. Okujima, and M. Tanaka, “A technique of ﬂow
mapping based on Doppler information,” J. Med. Ultrason., vol.
13, Suppl. 1, pp. 231–232, 1986.
[75] S. Ohtsuki, “Two dimensional imaging of blood ﬂow by ultrasonic Doppler technique,” J. Med. Ultrason., vol. 13, Suppl. II,
pp. 23–24, Oct. 1986, (in Japanese).
[76] S. Ohtsuki, M. Okujima, and M. Tanaka, “A method of ﬂow
vector mapping deduced from Doppler information,” J. Acoust.
Soc. Jpn., vol. 43, pp. 764–767, 1987, (in Japanese).
[77] M. Tanaka, A. Yamamoto, H. Ohkawai, N. Endo, M. Okujima,and S. Ohtsuki, “Flow vector distribution constructed from theinformation obtained from the unidirectional tracing. Analysisof the normal left ventricular ﬂow dynamics,” J. Med. Ultrason.,vol. 13, Suppl. 1, pp. 229–230, 1986.
[78] I. Takashima, S. Ohtsuki, M. Okujima, and M. Tanaka, “Estimation technique of dynamic pressure proﬁle based on Doppler
information,” J. Med. Ultrason., vol. 13, Suppl. 2, pp. 829–830,
1986, (in Japanese).
[79] A. Yamamoto, M. Tanaka, N. Endo, K. Takahashi, S. Ohtsuki,
and M. Okujima, “Two-dimensional dynamic pressure distribution of the left ventricle: Computer assisted mapping from ultrasound Doppler data,” J. Med. Ultrason., vol. 13, Suppl. 2, pp.
831–832, 1986, (in Japanese).
[80] S. Ohtsuki, M. Okujima, and M. Tanaka, “A method deducing
stream function and ﬂow vector distribution from Doppler velocity distribution-Stream function method,” J. Med. Ultrason.,vol. 15, Suppl. 2, pp. 255–256, 1988.
[81] N. Endo, M. Tanaka, A. Yamamoto, S. Ohtsuki, M. Okujima,
K. Takahashi, and S. Nitta, “The study of the intraventricularblood ﬂow changes in cases of myocardial infarction by two dimensional mappings of the stream lines and ﬂow volume,” J.
Med. Ultrason., vol. 15, Suppl. 2, pp. 461–462, 1988.
[82] M. Tanaka, “Usefulness of ultrasonic imaging in the medical
ﬁeld,” Acoust. Imaging, vol. 17, pp. 453–466, May 1988, H.
Shimizu, N. Chubachi, and J. Kushibiki, Eds. New York & London: Plenum Press.

22[83] S. Ohtsuki and M. Tanaka, “Flow function for stream lines representative of the ﬂow on a plane in three dimensional ﬂow,” J.
Visualir. Soc. Jpn., vol. 18, no. 69, pp. 40–44, 1998.
[84] M. Tanaka and S. Ohtsuki, “Evaluation of ﬂow parameters andtheir distribution in the heart,” in Proc. 2nd. Int. Congr. Card.
Doppler, 1986, pp. 37–38.
[85] M. Tanaka, S. Nitta, A. Yamamoto, S. Ohtsuki, K. Oba, N. Sato,
K. Takahashi, Y. Saijo, R. Oomote, and H. Ono, “Development
and application of noninvasive method for the evaluation of cardiac function, Measuring cardiac function,” Asian Med. J., vol.
37, no. 7, pp. 397–400, Jul. 1994.
[86] M. Tanaka, S. Nitta, A. Yamamoto, K. Takahashi, Y. Saijo, and
S. Ohtsuki, “Development and application of noninvasive methods for the evaluation of cardiac function, Quantifying intracardiac blood ﬂow,” Asian Med. J., vol. 37, no. 5, pp. 283–286,
May 1994.
[87] A. Yamamoto, M. Tanaka, H. Sogo, K. Nitta, N. Sato, S. Nitta,
and H. Okawai, “Non-invasive estimation of left ventricular outﬂow tract pressure in obstructive cardiomyopathy,” in Proc. 45th
Mtg. JSUM, 1984, pp. 217–218, (in Japanese).
[88] A. Yamamoto, M. Tanaka, N. Sato, H. Okawai, H. Sogo, S. Nitta,
K. Nitta, and Y. Katahira, “Pulsed Doppler evaluation of left
ventricular pressure and pressure diﬀerence in HOCM,” J. Cardiography, vol. 15, no. 4, pp. 981–994, 1985, (in Japanese).
[89] M. Tanaka, S. Nitta, and A. Yamamoto, “Development and application of non invasive method for the evaluation of cardiac
function: Visualization of pressure changes in the cardiac cavity,” Asian Med. J., vol. 37, no. 6, pp. 341–344, Jun. 1994.
[90] S. Ohtsuki and M. Tanaka, “Doppler pressure image introducedwith ultrasonic color Doppler information,” J. Med. Ultrason.,vol. 26, no. 4, p. 686, Apr. 1999.
[91] M. Tanaka, S. Sugawara, K. Nitta, Y. Katahira, S. Ohtsuki,
and S. Nitta, “Changes of the two dimensional Doppler-pressure
distribution in left ventricle during cardiac cycle and its pathophysiological signiﬁcance,” in Proc. 11th Annu. Mtg. Jpn. Soc.
Echocardiography, 2000, abst, p. 99.
[92] S. Sugawara, M. Tanaka, Y. Katahira, K. Nitta, H. Nakajima,
S. Ohtsuki, S. Nitta, and Y. Sijo, “Quantitative analysis of thevortex by the ﬂow function method,” J. Med. Ultrason., vol. 27,
no. 4, p. 703, 2000.

Motonao Tanaka was born in Tokyo, Japan
in 1932. He received the M.D. and Ph.D. degrees in medical science from Tohoku University, Sendai, Japan, in 1959 and 1963, respectively. He was with the Research Institute for Chest Diseases and Cancer, Tohoku
University, from 1959 to 1993 and was with
the Institute of Development Aging and Cancer from 1993 to 1994, where he was a professor of medicine and Head of the Department of Medical Engineering and Cardiology.
Since 1994, Dr. Tanaka has been the Presidentof Tohoku Welfare Pension Hospital and Professor Emeritus of Tohoku University. His research interests are diagnostic application of
acoustics to medicine and cardiology, low frequency range; mechanocardiography, audio frequency range; phono-cardiography, high frequency range; ultrasonics; echo-cardiography; and cardiac function
and tissue characterization. Dr. Tanaka is a member of the World
Federation for Ultrasound in Medicine and Biology, the JapaneseCollege of Cardiology, the Japan Society of Ultrasonics in Medicine,
the Acoustical Society of Japan, and the Japan Society of Medical
Electronics and Biological Engineering.