Doppler color flow image size: dependence on instrument settings

Doppler color flow imaging provides important qualitative information about the location and spatial distribution of intracardiac blood flow. However, the effect of instrument-related variables on the size of color Doppler images requires further definition. Flow of a silicone particle solution was established in a tube or cylinder and scanned as color gain, pulse repetition frequency, depth, and transducer frequency were varied. The diameter of Doppler color flow images were measured during constant laminar or disturbed flow parallel to the ultrasound beam and during laminar flow perpendicular to the ultrasound beam. The diameter of color Doppler images of laminar flow perpendicular and parallel to the beam varied directly with color gain. Diameter varied inversely with transducer frequency for laminar flow parallel to the transducer and inversely with pulse repetition frequency for laminar flow perpendicular to the transducer. The diameter of laminar flow parallel to the transducer varied directly with the depth of the flow area below the transducer. The size of the color flow dropout of laminar flow exactly perpendicular to the ultrasound beam varied directly with transducer frequency and inversely with gain. During disturbed flow parallel to the transducer, the diameter of the image varied directly with gain and inversely with transducer frequency and pulse repetition frequency. Instrument settings have a significant impact on the size of color Doppler images. Understanding the effects of changes in these variables is important for reliable diagnostic use of Doppler color flow imaging.     

Initial experience with a steerable, phased vector array ultrasound catheter in the GI tract

BACKGROUND: EUS requires a significant capital outlay. The ability to perform high-resolution phased array scanning and Doppler interrogation by using a catheter that interfaces with a standard US console could increase the accessibility of EUS. Recently, an electronic phased-array US catheter was developed for intracardiac use. To date, this technology has not been applied to the GI tract. The aim of this study is to determine the feasibility and imaging characteristics of a new phased array scanning US catheter in the GI tract. METHODS: Swine were placed under general anesthesia. This study used a 100 cm, 10F, torquable catheter with 4-way tip deflection to greater than 90 degrees. The catheter tip houses a phased vector array transducer with variable frequency (5.5-10 MHz) and variable focal distance. It has pulsed/color and power Doppler capability. The probe was passed through a therapeutic flexible sigmoidoscope into the upper GI tract. Acoustic coupling was achieved via a condom filled with water or by gastric water infusion. Needle visualization experiments were performed with a second endoscope (also passed per oral) with a standard EUS-guided fine needle aspiration needle. RESULTS: Acoustic coupling was easily achieved. Resolution of the GI wall into characteristic layers (esophagus 5, stomach 7) was demonstrated. At 5.5 MHz, tissue resolution and Doppler imaging were excellent to greater than 10 cm from the transducer. A 22-gauge EUS-guided fine needle aspiration needle was easily visualized at depth greater than 4 cm. Flow in gastric, hepatic, and pancreatic parenchymal vessels approximately 1 mm diameter was visualized by using power and color Doppler. CONCLUSIONS: This 10F array US catheter is capable of high-resolution two-dimensional imaging of the gut wall as well as high-quality Doppler imaging. The Doppler capabilities of this equipment may have new GI applications.     

Improved diagnosis and characterization of left ventricular pseudoaneurysm by Doppler color flow imaging

Three patients with a left ventricular pseudoaneurysm are presented. Doppler color flow imaging helped to establish the diagnosis and was able to show additional blood flow abnormalities. The guided continuous wave Doppler interrogation of the shunting blood flow through the communication between the pseudoaneurysm and the left ventricle allowed the identification of a specific diagnostic flow pattern. Doppler color flow imaging offers advantages in patients with equivocal two-dimensional echocardiographic findings for elucidating confusing clinical findings and demonstrating additional and unsuspected flow abnormalities.     

A unique case of “double‐orifice aortic valve”—comprehensive assessment by 2‐, 3‐dimensional,and color Doppler echocardiography

Transesophageal echocardiography (TEE) is a powerful imaging tool for the comprehensive assessment of valvular structure and function. TEE may be of added benefit when anatomy is difficult to delineate accurately by transthoracic echocardiography. In this article, we present 2‐, 3‐dimensional, and color Doppler TEE images from a male patient with aortic stenosis. A highly unusual and complex pattern of valvular calcification created a functionally “double‐orifice” valve. Such an abnormality may have implications for the accuracy of continuous‐wave Doppler echocardiography, which assumes a single orifice valve in native aortic valves.     

Initial experience with a multiplane transoesophageal echo-transducer: assessment of diagnostic potential.

BACKGROUND: the prototype of a transoesophageal echocardiographic transducer with a rotatable cross-sectional scanning plane underwent initial evaluation. METHODS: the 5 MHz, phased array, 64 element transducer is incorporated into a 16 by 11 by 40 mm echoscope tip. The instrument also has pulsed wave and colour flow Doppler capabilities. Exterior controls allow continuous mechanical rotation of the scanning plane from 0 degree, corresponding to the conventional transverse plane, through 180 degrees, thereby encompassing all possible planes. RESULTS: 103 patients underwent examination without complications; two additional patients were excluded because of difficulty in swallowing the probe. Advantages include precise alignment of aortic valve long- and short-axis views, long-axis views of the ascending aorta (mean visualized length: 6 cm), and full scanning of the entire circumference of the mitral valve and the left ventricle. Separation of paravalvular and transvalvular leakage in prosthetic valves is distinctly improved. CONCLUSION: multiplanar transoesophageal imaging is feasible and increases the diagnostic yield, especially in mitral and aortic pathology and in the assessment of left ventricular wall motion. Three-dimensional reconstruction is an attractive potential application.     

Transvascular Imaging: Feasibility Study Using a Vector Phased Array Ultrasound Catheter

Background: Transvascular imaging is defined as the acquisition of anatomic and functional information of structures lying beyond the confines of a vascular conduit within which the imaging device resides. Interrogating structures surrounding the vascular conduit is the subject of this feasibility study using a novel underblood, phased array ultrasound-tipped catheter. Methods: An intravascular catheter (10-F, 3.2-mm-diameter, four-way articulation) tipped with a 5.5- to 10-MHz frequency agile, vector phased array transducer with full Doppler capability (Sequoia, Acuson) was used. The imaging transducer has a wide range of tissue penetration (2 mm to >10 cm from the lens). The catheter was introduced via an 11-Fr femoral venous sheath into the inferior and superior vena cavae and right heart chambers. As the catheter was advanced, attention was directed to visualization of structures surrounding the vessel in which the catheter resided. Results: From the cavae and femoral vein the thoracic, abdominal and femoral arteries could be easily imaged. Anatomy that was visualized included the liver, hepatic veins, gallbladder, and mesenteric vessels. Normal and pathological anatomy and Doppler physiology could be readily appreciated. Doppler (i.e., pulsed- and continuous-wave, color flow, and tissue Doppler) fostered unique transvascular physiological hemo-dynamic and flow assessment. Conclusion: Transvascular imaging is feasible in human subjects using this 10-Fr catheter tipped with a 5.5- to 10 MHz vector phased array transducer. Intravascular navigation to a desired location within the body and the performance of diagnostic or therapeutic procedures at a remote site under direct ultrasound visualization are possible. Full Doppler capability extends the concept of transvascular hemodynamic and physiological assessment.     

Sensitivity and speed of colour Doppler flow mapping compared with continuous wave Doppler for the detection of ventricular septal defects

Twenty nine patients (aged from three months to 37 years) with confirmed or suspected ventricular septal defects were studied separately by three examiners who used colour flow mapping and imaging, or continuous wave Doppler and imaging, or a combined reference examination. Colour flow mapping identified 19 of the 25 patients with a ventricular septal defect, continuous wave Doppler echocardiography identified 18, and the combined reference examination identified 24. Two of four patients without ventricular septal defect had a false positive result with colour flow mapping and none had a false positive result with continuous wave Doppler examination. During the reference examination continuous wave Doppler identified 24 patients with ventricular septal defects and colour flow mapping identified 23. In two patients a second ventricular septal defect was found by colour flow mapping, and confirmed by continuous wave Doppler. There was no significant difference in time to diagnosis between the two techniques. Colour flow mapping aids identification of multiple ventricular septal defects but is not faster and has lower specificity than continuous wave Doppler. A combination of the two techniques gave the highest sensitivity and specificity.     

Signal processing in 2 dimensional Doppler echocardiography

Blood flow recordings made by 2 dimensional Doppler echocardiography can sometimes be understood more easily than conventional Doppler recordings, because of the anatomical 2 dimensional presentation. In contrast, signal processing has become more complicated and requires more explanation. In 2 dimensional Doppler echocardiography the analog ultrasonic signal received by the transducer is converted into an audible signal, which next is digitized and analyzed for its mean frequency and variance. Data collection and processing require application of multigating and high speed frequency analysis, generally based upon autocorrelation. Some artifacts may be perceived, such as color reversal due to aliasing, deceptively colored tissue surfaces due to beam motion, and wall motion ghost signals due to multiple reflections. Color flow imaging is appropriate for a rapid scan of the heart cavities to detect and roughly evaluate flow abnormalities. Quantification is still accomplished by switching to conventional Doppler mode.     

Sensitivity and speed of colour Doppler flow mapping compared with continuous wave Doppler for the detection of ventricular septal defects.

Twenty nine patients (aged from three months to 37 years) with confirmed or suspected ventricular septal defects were studied separately by three examiners who used colour flow mapping and imaging, or continuous wave Doppler and imaging, or a combined reference examination. Colour flow mapping identified 19 of the 25 patients with a ventricular septal defect, continuous wave Doppler echocardiography identified 18, and the combined reference examination identified 24. Two of four patients without ventricular septal defect had a false positive result with colour flow mapping and none had a false positive result with continuous wave Doppler examination. During the reference examination continuous wave Doppler identified 24 patients with ventricular septal defects and colour flow mapping identified 23. In two patients a second ventricular septal defect was found by colour flow mapping, and confirmed by continuous wave Doppler. There was no significant difference in time to diagnosis between the two techniques. Colour flow mapping aids identification of multiple ventricular septal defects but is not faster and has lower specificity than continuous wave Doppler. A combination of the two techniques gave the highest sensitivity and specificity.     

Initial clinical trial of a multi-planar transesophageal echoscope]

The prototype of a multiplanar transesophageal echocardiographic transducer was evaluated clinically. This 5 MHz, phased array, 64-element transducer allows to continuously rotate the imaging plane from the transverse (0 degree) position to a maximal 180 degrees position, thus encompassing transverse, longitudinal, and every intermediate position. The transducer is incorporated in the echoscope tip measuring 16 by 11 by 40 mm. The shaft of the instrument is 110-cm long and has a 9-mm diameter. The instrument has pulsed wave, continuous wave, and color Doppler capabilities. 176 clinical patients were examined with the multiplane transducer. No complications occurred. Advantages of this transducer included: 1) comprehensive scanning of the whole mitral circumference and mitral valve; 2) quick and precise alignment of aortic valve long and short axis views, including long axis views of the ascending aorta, with a mean visualized length of 6 cm; 3) improved imaging and evaluation of transvalvular and paravalvular regurgitant jets in mitral and aortic valve prostheses; 4) complete evaluation of all left ventricular segments using multiple planes from transgastric and transesophageal transducer positions. An important potential application is three-dimensional reconstruction of cardiac structures and color Doppler jets.     

Doppler diagnosis in peripheral arterial occlusive disease

PHYSICAL AND TECHNICAL FUNDAMENTALS OF DOPPLER ULTRASONOGRAPHIC METHODS: In addition to units recording both velocity and direction of blood flow, mostly using two ultrasonic frequencies and phase-out technique, there are small non-directional units available which provide useful diagnostic information from the acoustic Doppler signal derived. Doppler ultrasonic techniques utilize two physical phenomena: a) High-frequency ultrasonic energy penetrates biologic tissue and is partially reflected at borders between tissues of differing density. b) If the border area is in motion, due to the Doppler effect, there is a change in the reflected ultrasonic frequency with respect to the frequency emitted. In blood vessels the ultrasonic beam is primarily reflected from the flowing red blood cells where the change in frequency is a function of the velocity of flow (Doppler effect). From the Doppler transducer, the continuously-emitted ultrasonic beam is also received after being reflected. The frequency of the reflected beam is directly proportional to the velocity of the flowing blood. If flow is directed toward the transducer, the frequency of the reflected beam increases and if the flow is away from the transducer, the converse is true. The best Doppler signals can be received when the angle beta of the transducer to the studied vessel is about 45 degrees. The unprocessed Doppler signal represents a frequency spectrum corresponding to the various velocities of the individual lamina of the blood stream from which the prevailing velocity is integrated and registered. The penetration depth is dependent on the frequency emitted. Doppler units are preferred with working frequencies of 8 to 10 MHz and 3 to 5 MHz. With 8 MHz, the maximal depth of penetration is 3.5 cm, with 4 MHz, 8 cm. The lowest detectable velocity is also dependent on the frequency emitted: with 8 MHz, minimum is 3 cm/s. Since flow toward the transducer results in a positive Doppler shift and flow away in a negative shift, with the Doppler signal, the direction of flow can also be determined. The recorded Doppler curves enable a qualitative and, to some degree, quantitative assessment. Phase-out and frequency analysis systems enable differentiation of forward and backward flow components. From separate forward and backward flow curves, the instantaneous summation curve (integrated instantaneous hemotachygram) as well as a trend curve over 5 to 7 seconds can be constructed and the mean flow velocity displayed.     

Intraoperative transesophageal echocardiography of ventricular septal defect

The accuracy and limitations of intraoperative two-dimensional (2-D) and color Doppler flow mapping transesophageal echocardiography (TEE) of ventricular septal defect (VSD), before and after cardiopulmonary bypass, were analyzed in 62 children. Twenty-one patients had an isolated VSD, and 41 had a VSD plus additional cardiac anomalies. Two-dimensional and color Doppler flow mapping TEE were performed with a miniaturized 5-MHz single (transverse) plane transducer in the 51 of 62 patients weighing less than 20 kg. The remaining 11 were monitored using a single plane adult probe (n = 4) and a biplane (transverse plus longitudinal) probe (N = 7). Prebypass TEE provided a correct diagnosis in 57 of 62 cases (92%) and corrected an erroneous preoperative transthoracic echocardiographic diagnosis in three of 62 cases (5%). Single plane TEE diagnosis was erroneous in five patients: four with doubly-committed subarterial VSD and one with multiple small apical muscular defects and pulmonary hypertension. Biplane TEE (transverse longitudinal) provided clear and complete imaging of the right ventricular outflow tract in all seven cases in whom it was used. Postbypass TEE showed absence of a hemodynamically significant residual VSD in 30 of 40 patients (95%) who underwent VSD patch closure, prospectively identified two of 40 with significant residual VSD, and accurately measured the color Doppler jet width of all residual VSDs. We conclude that hemodynamically significant VSDs can be identified immediately after cardiopulmonary bypass based on the width of the residual VSD color Doppler flow map jet. Therefore, 2-D and color Doppler flow mapping TEE provide an accurate diagnosis in most cases of VSD but may miss doubly-committed subarterial and apical muscular VSD unless biplane TEE is used.     

Colour flow Doppler mapping in the assessment of prosthetic valve regurgitation

Two hundred Carpentier-Edwards, Bj?rk-Shiley, and Starr-Edwards prostheses in 173 patients were examined. Sixteen (16%) in the aortic and 24 (25%) in the mitral position were associated with clinical signs of regurgitation. A phased array system (Hewlett-Packard A77020A) with a 2.5 MHz duplex and 1.9 MHz continuous wave transducer was used. Colour flow mapping showed trivial transvalvar regurgitation in 23 (53%) metal aortic prosthesis, and only nine (20%) metal mitral prostheses. This difference was probably attributable to shielding of the left atrium by the metal components. Colour mapping confirmed abnormal regurgitation in all aortic prostheses with early diastolic numbers, but regurgitation was also shown in 25 (29%) with no diastolic murmur. Abnormal mitral regurgitation was found in 13 (54%) patients with a pansystolic murmur, but also in six (8%) with no systolic murmur. Two patients, thought on clinical grounds to have mild mitral regurgitation, had unexpectedly large jets on colour flow mapping. About one in three prostheses had paraprosthetic leaks, 65 (79%) of which were small with a jet area less than 20% of the area of the receiving chamber. The development of new paraprosthetic leaks led to the diagnosis of bacterial endocarditis in two patients. In eight patients regurgitation was first diagnosed with continuous wave Doppler, but was afterwards shown with colour mapping and in a further 10 regurgitation could only be shown by continuous wave Doppler. Colour flow mapping was less sensitive than continuous wave Doppler in detecting regurgitation,but seemed able to distinguish normal transvalvar from paraprosthetic regurgitation. Further studies in the natural course of paraprosthetic leaks and a comparison of the transoesophageal and transthoracic approaches in the assessment of mitral prostheses are needed.     

Colour flow Doppler mapping in the assessment of prosthetic valve regurgitation.

Two hundred Carpentier-Edwards, Björk-Shiley, and Starr-Edwards prostheses in 173 patients were examined. Sixteen (16%) in the aortic and 24 (25%) in the mitral position were associated with clinical signs of regurgitation. A phased array system (Hewlett-Packard A77020A) with a 2.5 MHz duplex and 1.9 MHz continuous wave transducer was used. Colour flow mapping showed trivial transvalvar regurgitation in 23 (53%) metal aortic prosthesis, and only nine (20%) metal mitral prostheses. This difference was probably attributable to shielding of the left atrium by the metal components. Colour mapping confirmed abnormal regurgitation in all aortic prostheses with early diastolic numbers, but regurgitation was also shown in 25 (29%) with no diastolic murmur. Abnormal mitral regurgitation was found in 13 (54%) patients with a pansystolic murmur, but also in six (8%) with no systolic murmur. Two patients, thought on clinical grounds to have mild mitral regurgitation, had unexpectedly large jets on colour flow mapping. About one in three prostheses had paraprosthetic leaks, 65 (79%) of which were small with a jet area less than 20% of the area of the receiving chamber. The development of new paraprosthetic leaks led to the diagnosis of bacterial endocarditis in two patients. In eight patients regurgitation was first diagnosed with continuous wave Doppler, but was afterwards shown with colour mapping and in a further 10 regurgitation could only be shown by continuous wave Doppler. Colour flow mapping was less sensitive than continuous wave Doppler in detecting regurgitation,but seemed able to distinguish normal transvalvar from paraprosthetic regurgitation. Further studies in the natural course of paraprosthetic leaks and a comparison of the transoesophageal and transthoracic approaches in the assessment of mitral prostheses are needed.     

Important Advances In Technology: Echocardiography

Echocardiography has evolved over the past 45 years from a simple M-mode tracing to an array of technologies that include two-dimensional imaging, pulsed and continuous wave spectral Doppler, color flow and tissue Doppler, and transesophageal echocardiography. Together, these modalities provide a comprehensive anatomic and functional evaluation of cardiac chambers and valves, pericardium, and ascending and descending aorta. The switch from analog to digital signal processing revolutionized the field of ultrasound, resulting in improved image resolution, smaller instrumentation that allows bedside evaluation and diagnosis of patients, and digital image storage for more accurate quantification and comparison with previous studies. It also opened the door for new advances such as harmonic imaging, automated border detection and quantification, 3-dimensional imaging, and speckle tracking. This article offers an overview of some newer developments in echocardiography and their promising applications.     

Effect of heart rate on tissue Doppler measures of diastolic function

BACKGROUND: Our aim was to study the independent effect of heart rate (HR) on parameters of diastolic function, particularly mitral annular velocities measured by tissue Doppler imaging (TDI), an effect which is not well understood. METHODS: Sixteen patients with dual chamber pacemakers attending for routine pacemaker review underwent detailed echocardiographic assessment during atrial pacing with intact atrioventricular conduction at baseline and accelerated HRs. Mitral inflow and annular tissue Doppler velocities and systolic strain parameters were compared. RESULTS: Parameters of systolic function were unaffected by increased HR. When these parameters were compared at baseline (mean 67 bpm) and accelerated HR (mean 80 bpm), the following was observed: a significant decrease in early mitral inflow (E) wave (70.5 +/- 5.5 cm/s vs 63.5 +/- 4.9 cm/s, P < 0.02) and early mitral annular (E') velocities (7.0 +/- 0.5 cm/s vs 6.3 +/- 0.6 cm/s, P < 0.003) and a significant increase in mitral inflow A wave (70.3 +/- 4.5 cm/s vs 77.3 +/- 4.4 cm/s, P < 0.05) and late mitral annular (A') velocities (9.3 +/- 0.6 cm/s vs 10.8 +/- 0.5, P < 0.00004). CONCLUSION: Changes in HR have previously unrecognized significant effects on tissue Doppler parameters of diastolic function. Further study is required to determine if tissue Doppler derived annular velocities should be corrected for HR.     

Changes in regional left atrial function with aging: evaluation by Doppler tissue imaging.

AIMS: This study applies pulsed wave Doppler tissue imaging and colour Doppler tissue imaging to study changes in atrial function with ageing. We tested the following hypotheses: (1) pulsed wave Doppler tissue imaging can detect global changes of left atrial function associated with ageing similar to standard echocardiographic methods, (2) colour Doppler tissue imaging can reproducibly detect regional changes in atrial function (wall motion) of the normal young and normal aging atrium. METHODS AND RESULT: We studied 92 healthy subjects, divided into Group B (>or=50 years) and Group A (<50 years). As a reference standard the conventional measures of atrial function were determined: peak mitral A wave velocity, A wave velocity time integral, atrial emptying fraction and atrial ejection force. Pulsed wave Doppler tissue imaging estimated atrial contraction velocity (A' velocity) in late diastolic and segmental atrial contraction was determined by colour Doppler tissue imaging. A' velocities were significantly higher in Group B vs Group A (9.8+/-1.8 vs 8.5+/-1.5cm/s; P=0.0005). A' velocity correlated with atrial fraction (r=0.28; P=0.007) and atrial ejection force (r=0.21; P=0.04). Age correlated significantly with atrial ejection force (r=0.47; P=0.0001), atrial fraction (r=0.61; P=0.0001) and A' velocity (r=0.4; P=0.0002). Longitudinal segmental atrial contraction using colour Doppler tissue imaging showed an annular to superior segment decremental gradient with contraction velocities higher in Group B vs Group A. CONCLUSION: Pulsed wave Doppler tissue imaging and colour Doppler tissue imaging are reproducible and readily obtained parameters that provide unique data about global and segmental atrial contraction. In this study, changes in atrial contraction with aging were consistent with increased atrial contribution to filling accomplished by augmented atrial contractility.     

An ultrasound system for combined cardiac imaging and Doppler blood flow measurement in man

An ultrasound instrument has been developed that combines a real-time cross-sectional imaging system and a spectrum analyzer-based Doppler velocimeter. This combination allows the Doppler sample volume to be superimposed on the cross-sectional image of the heart so that the sample volume can be located accurately. The same 2.2 MHz transducer utilized for cross-sectional imaging is stopped mechanically and quickly switched to transmit and receive the Doppler ultrasound signal. Preliminary experience in 20 young and adult normal subjects indicates that it is possible to place the Doppler sample volume in the proximal main pulmonary artery at a point where the sound beam and blood flow stream are parallel. Measurement of the distance from transducer to the sample volume and the peak blood flow velocities in the main pulmonary artery of normal subjects indicates that these quantities are within the measurement capabilities of the system. The ultimate goal of this device is to make measurements of volume blood flow in man noninvasively.     

Non-invasive grading of aortic regurgitation by Doppler ultrasonography

Doppler ultrasound without concomitant echocardiographic imaging was used to grade isolated aortic regurgitation in 21 patients. The severity of aortic regurgitation was subsequently graded (from 0 to IV) angiographically. A 2 MHz continuous wave Doppler transducer was placed over the apex of the heart and the beam was aimed parallel to the mitral flow by means of acoustic guidance. Mitral pressure half time was calculated from the analogue maximum velocity tracing and it was less than or equal to 60 ms in 10 controls; 50-120 ms in five patients with grade II, 120-160 ms in nine patients with grade III, and greater than or equal to 160 ms in seven patients with grade IV aortic regurgitation. These results indicate that a semi-quantitative grading of aortic regurgitation may be obtained non-invasively with non-imaging Doppler ultrasonography in patients without concomitant mitral valve disease.     

Three-dimensional and four-dimensional transesophageal echocardiographic imaging of the heart and aorta in humans using a computed tomographic imaging probe

We evaluated the clinical applicability of a prototype tomographic transesophageal echocardiographic (TEE) system, which not only provides conventional TEE images but also three-dimensional tissue reconstruction and four-dimensional display capabilities. The probe was used in 16 patients in the echocardiographic laboratory, intensive care unit, and the operating room. The instrument is a 5-MHz, 64-element, phased array unit mounted on a sliding carriage within a casing. After appropriate probe placement within the esophagus, the probe is straightened, a balloon surrounding the probe is inflated, and data acquisition begun with ECG and respiration gating. With computer controlled transducer movement at 1-mm increments, a complete cardiac cycle is recorded at each tomographic level. These are processed using a dedicated four-dimensional software, and displayed as a dynamic three-dimensional tissue image of the heart. We were able to see the dynamic motion of the ventricles and all the valves in the four-dimensional format. In addition to four-dimensional display, we were able to cut and visualize the heart in dynamic mode in any desired plane and also in multiple planes. Patients tolerated the procedure well. We conclude that this tomographic four-dimensional approach, which does not require tedious off-line processing, can easily be performed in patients and has a strong clinical potential.