Single pulse frequency compounding protocol for superharmonic imaging.

Second harmonic imaging is currently accepted as the standard in commercial echographic systems. A new imaging technique, coined as superharmonic imaging (SHI), combines the third till the fifth harmonics, arising during nonlinear sound propagation. It could further enhance the resolution and quality of echographic images. To meet the bandwidth requirement for SHI a dedicated phased array has been developed: a low frequency subarray, intended for transmission, interleaved with a high frequency subarray, used in reception. As the bandwidth of the elements is limited, the spectral gaps in between the harmonics cause multiple (ghost) reflection artifacts. A dual-pulse frequency compounding method aims at suppressing those artifacts at a price of a reduced frame rate. In this study we explore a possibility of performing frequency compounding within a single transmission. The traditional frequency compounding method suppresses the ripples by consecutively emitting two short Gaussian bursts with a slightly different center frequency. In the newly proposed method, the transmit aperture is divided into two parts: the first half is used to send a pulse at the lower center frequency, while the other half simultaneously transmits at a slightly higher center frequency. The suitability of the protocol for medical imaging applications in terms of the steering capabilities was performed in a simulation study with INCS and the hydrophone measurements. Moreover, an experimental study was carried out to find the optimal parameters for the clinical imaging protocol. The latter was subsequently used to obtain the images of a tissue mimicking phantom containing strongly reflecting wires. Additionally, the images of a human heart in the parasternal projection were acquired. The scanning aperture with the developed protocol amounts to approximately 90°, which is sufficient to capture the cardiac structures in the standard anatomical projections. The theoretically estimated and experimentally measured grating lobe levels are equal to -28.3 dB and -35.9 dB, respectively. A considerable improvement in the axial resolution of the SHI component (0.73 mm) at -6 dB in comparison with the third harmonic (2.23 mm) was observed. A similar comparison in terms of the lateral resolution slightly favored the superharmonic component by 0.2 mm. Additionally, the images of the tissue mimicking phantom exhibited the absence of the multiple reflection artifacts. The in-vivo acquisition allows one to clearly observe the dynamic of the mitral valve leaflets. The new method is equally effective in eliminating the ripple artifacts associated with SHI as the dual-pulse technique, while the full frame rate is maintained.

Microsphere embolisation as an alternative for alcohol in percutaneous transluminal septal myocardial ablation.

BACKGROUND: Percutaneous transluminal septal myocardial ablation using microsphere embolisation is a new interventional technique to treat patients with hypertrophic obstructive cardiomyopathy. METHODS AND RESULTS: In two patients, considered at high risk for myectomy, targeted septal perforators were occluded with microsphere embolisation instead of alcohol ablation to reduce left ventricular outflow gradient. In both cases the left ventricular outflow tract gradient was immediately reduced. No adverse events occurred. CONCLUSION: This is the first clinical experience with Embozene® Microspheres in the Netherlands as an alternative for alcohol septal ablation. In both cases it resulted in immediate improvement in the haemodynamics, without any adverse events.

Paradoxical effects of interatrial conduction delay in a hypertrophic cardiomyopathy patient in the long-term: time is a great healer.

We present a unique case where early proarrhythmic and late antiarrhythmic characteristics of interatrial conduction delay were observed during the long-term progression of HCM. Occurrence of AT constantly increased as the interatrial conduction delay became more prominent, while the P-wave width in sinus rhythm and the AT cycle length both showed an instantaneous increase in parallel. As the interatrial delay reached a critical point, the right and left atrial P-wave became virtually separated, as demonstrated by the findings of ECGs and echocardiography. This phenomenon resulted in the complete cessation of tachycardias.

Contrast echocardiography: mechanism of action, safety and clinical applications.

Since its initial description by Gramiak and Shah in 1968, contrast echocardiography has become an established practice world-wide. Microbubbles have the unique property of being pure intravascular tracers. The basic rationale behind bubble imaging is the characteristic responses to ultrasound power that results in enhanced ultrasound images from the blood pool. Therefore, whenever there is blood pool there is a potential application for contrast ultrasound. Clinical applications of contrast echocardiography have been vastly grown from diagnostic applications such as detection of a persistent foramen ovale to drug delivery. This article reviews the mechanism of action, safety and clinical applications of contrast echocardiography.

Influence of the pattern of hypertrophy on left ventricular twist in hypertrophic cardiomyopathy.

BACKGROUND/OBJECTIVE: Left ventricular (LV) twist has an important role in LV function. The influence of the pattern of LV hypertrophy on LV twist in hypertrophic cardiomyopathy (HCM) patients is unknown. This study sought to assess LV twist in a large group of HCM patients according to the pattern of LV hypertrophy. METHODS: The final study population consisted of 43 patients with HCM (mean age 43 (15) years, 31 men) and a typical sigmoidal (n = 16) or reverse septal curvature (n = 27) and 43 age-matched and gender-matched healthy control subjects. LV peak systolic rotation (Rot(max)), LV peak systolic twist (Twist(max)) and untwisting at 5%, 10% and 15% of diastole were determined by speckle tracking echocardiography (STE). RESULTS: Compared to control subjects, HCM patients had increased basal Rot(max) (-5.5 degrees (2.3 degrees ) vs -3.4 degrees (1.7 degrees ), p<0.001) and comparable apical Rot(max) (7.3 degrees (3.1 degrees ) vs 7.0 degrees (2.2 degrees ), p = NS), resulting in increased Twist(max) (12.4 degrees (4.0 degrees ) vs 9.9 degrees (2.7 degrees ), p<0.01). Untwisting at 5%, 10% and 15% of diastole was decreased in HCM patients (all p<0.05). There was a striking difference in apical Rot(max )(9.4 degrees (2.8 degrees ) vs 6.0 degrees (2.6 degrees ), p<0.01) and Twist(max) (15.3 degrees (3.2 degrees ) vs 10.6 degrees (3.3 degrees ), p<0.01) between HCM patients with a sigmoidal and reverse septal curvature. CONCLUSIONS: STE may provide novel non-invasive indices to assess LV function in patients with HCM. Apical Rot(max) and Twist(max) in HCM patients are dependent on the pattern of LV hypertrophy.

Cardiac evaluation in children and adults with Pompe disease sharing the common c.-32-13T>G genotype rarely reveals abnormalities.

BACKGROUND AND OBJECTIVE: Pompe disease is an inherited metabolic disorder caused by deficiency of acid alpha-glucosidase. All affected neonates have a severe hypertrophic cardiomyopathy, leading to cardiac failure and death within the first year of life. We investigated the presence and extent of cardiac involvement in children and adults with Pompe disease with the common c.-32-13T>G genotype to determine the usefulness of cardiac screening in these patients with relatively 'milder' phenotypes. METHODS: Cardiac dimensions and function were evaluated through echocardiography, electrocardiography and Holter monitoring. The total group comprised 68 patients with Pompe disease, of whom 22 patients had disease onset before the age of 18. RESULTS: Two patients (3%) had cardiac abnormalities possibly related to Pompe disease: Electrocardiography showed a Wolff-Parkinson-White pattern in an 8-year-old girl, and one severely affected adult patient had a mild hypertrophic cardiomyopathy. This hypertrophy did not change during treatment with recombinant human alpha-glucosidase. In addition, four adult patients showed minor cardiac abnormalities which did not exceed the prevalence in the general population and were attributed to advanced age, hypertension or pre-existing cardiac pathology unrelated to Pompe disease. CONCLUSIONS: Cardiac involvement is rare in Pompe patients with the common c.-32-13T>G genotype. The younger patients were not more frequently affected than the adults. Electrocardiographic evaluation appears to be appropriate as initial screening tool. Extensive cardiac screening seems indicated only if the electrocardiogram is abnormal or the patient has a history of cardiac disease.

Dobutamine stress MRI versus threedimensional contrast echocardiography: It's all Black and White.

Dobutamine stress magnetic resonance imaging is considered the superior stress modality to detect wall motion abnormalities. In this report we demonstrate the strengths of a newly developed stress modality: dobutamine stress contrastenhanced real-time three-dimensional echocardiography. This stress modality may become a competitor of stress magnetic resonance imaging allowing fast acquisition and an unlimited number of left ventricular cross sections. Unfortunately, at the moment adequate imaging with stress realtime three-dimensional echocardiography is only possible in a minority of cardiac patients. (Neth Heart J 2008;16:217-8.).

Cardiac involvement in adults with Pompe disease.

BACKGROUND: Glycogen storage disease type II or Pompe disease is a neuromuscular disorder caused by deficiency of lysosomal acid alpha- glucosidase. Classic infantile Pompe disease results in massive left ventricular (LV) hypertrophy and failure. Although Pompe disease is often included in the differential diagnosis of LV hypertrophy the true frequency of cardiac involvement in adults with Pompe disease is not known. METHODS: Forty-six consecutive adult patients (mean age 48 +/- 12, 22 men) with Pompe disease were included. Each patient underwent a clinical examination, electrocardiography, and rest and low-dose dobutamine (in 20 patients) two-dimensional echocardiography including contrast and tissue Doppler imaging. RESULTS: All patients had limited exercise tolerance; a rollator walking aid was used in seven patients (15%), a wheelchair in 13 patients (28%), and assisted ventilation in 14 patients (30%). Prior to this study, one patient was known with permanent atrial fibrillation, His-bundle ablation and a VVI pacemaker and another patient was known with fluid retention. The first patient had increased LV end-diastolic diameter, impaired LV ejection fraction, low systolic mitral annular velocities and diastolic dysfunction grade II. The patient with fluid retention was wheelchair bound and dependent on 24-h assisted ventilation and showed right ventricular and LV hypertrophy (septum 16 mm, posterior wall 15 mm). LV hypertrophy was not seen in any of the other patients. One woman of advanced age had isolated low systolic mitral annular velocities. Mean global systolic LV function, including contractile reserve, was not decreased in patients with Pompe disease. Eight patients (17%) had mild diastolic dysfunction grade I, related to hypertension in four and advanced age in seven. CONCLUSIONS: In adult patients with Pompe disease without objective signs of cardiac affection by 12-leads electrocardiography or physical examination, echocardiographic screening for LV hypertrophy seems not effective.

Clinical usefulness of SonoVue contrast echocardiography: the Thoraxcentre experience.

Although other imaging techniques, such as magnetic resonance imaging and computer tomography, are becoming more and more important in cardiology, two-dimensional echocardiography is still the most used technique in clinical cardiology. Quantification of left ventricular function and dimensions is important because therapeutic strategies, for example implanting an ICD after myocardial infarction, are based on ejection fraction measurements. Because of the sometimes low quality of echocardiographic images we started to use an ultrasound contrast agent and in this article we describe our experiences with SonoVue, a second-generation contrast agent, over a threeyear period in the Thoraxcentre. (Neth Heart J 2007;15:55-60.).

Cardiac abnormalities in adults with the attenuated form of mucopolysaccharidosis type I.

BACKGROUND: Cardiac involvement in mucopolysaccharidosis type I (MPS I) has been studied primarily in its most severe forms. Cardiac involvement, particularly left ventricular (LV) systolic and diastolic function, in the attenuated form of MPS I is less well known. METHODS: Cardiac function was prospectively investigated in 9 adult patients with the attenuated form of MPS I. All patients underwent 12-lead electrocardiography, 24 h Holter monitoring and two-dimensional echocardiography including tissue Doppler imaging (TDI). Eighteen age- and sex-matched healthy volunteers served as a control group. RESULTS: Aortic, mitral and tricuspid valve thickening was seen in, respectively, 5 (56%), 4 (44%) and 2 (22%) patients. Moderate mitral valve stenosis was seen in 1 patient and moderate aortic stenosis in 2 patients. All patients had mild-to-moderate aortic and mitral valve regurgitation and 6 patients (67%) had mild-to-moderate tricuspid valve regurgitation. Despite normal LV dimensions, ejection fraction and mass index, MPS patients had lower mean systolic mitral annular velocities (6.1 +/- 0.6 vs 9.1 +/- 1.4 cm/s, p < 0.01) compared to normal control subjects. Similarly, mean early diastolic mitral annular velocities were lower in MPS patients (7.8 +/- 0.9 vs 13.3 +/- 3.3 cm/s, p < 0.01). CONCLUSION: MPS I patients with the attenuated phenotype have not only valvular abnormalities but also LV diastolic and systolic abnormalities.

Rapid and accurate measurement of left ventricular function with a new second-harmonic fast-rotating transducer and semi-automated border detection.

Measurement of left ventricular (LV) volume and function are the most common clinical referral questions to the echocardiography laboratory. A fast, practical, and accurate method would offer important advantages to obtain this important information. To validate a new practical method for rapid measurement of LV volume and function. We developed a continuous fast-rotating transducer, with second-harmonic capabilities, for three-dimensional echocardiography (3DE). Fifteen cardiac patients underwent both 3DE and magnetic resonance imaging (reference method) on the same day. 3DE image acquisition was performed during a 10-second breath-hold with a frame rate of 100 frames/sec and a rotational speed of 6 rotations/sec. The individual images were postprocessed with Matlab software using multibeat data fusion. Subsequently, with these images, 12 datasets per cardiac cycle were reconstructed, each comprising seven equidistant cross-sectional images for analysis in the new TomTec 4DLV analysis software, which uses a semi-automated border detection (ABD) algorithm. The ABD requires an average analysis time of 15 minutes per patient. A strong correlation was found between LV end-diastolic volume (r = 0.99; y = 0.95x - 1.14 ml; SEE = 6.5 ml), LV end-systolic volume (r = 0.96; y = 0.89x + 7.91 ml; SEE = 7.0 ml), and LV ejection fraction (r = 0.93; y = 0.69x + 13.36; SEE = 2.4%). Inter- and intraobserver agreement for all measurements was good. The fast-rotating transducer with new ABD software is a dedicated tool for rapid and accurate analysis of LV volume and function.

Ultrafiltration improves aortic compliance in haemodialysis patients.

An elevated pulse pressure leads to an increased pulsatile cardiac load, and results from arterial stiffening. The aim of our study was to test whether a reduction in volume overload by ultrafiltration (UF) during haemodialysis (HD) leads to an improvement of aortic compliance. In 18 patients, aortic compliance was estimated noninvasively before and after HD with UF using a pulse pressure method based on the Windkessel model. This technique has not been applied before in a dialysis population, and combines carotid pulse contour analysis by applanation tonometry with aortic outflow measurements by Doppler echocardiography. The median UF volume was 2450 ml (range 1000-4000 ml). The aortic outflow volume after HD (39 ml; 32-53 ml) was lower (P=0.01) than before (46 ml; 29-60 ml). Carotid pulse pressure after HD (42 mmHg; 25-85 mmHg) was lower (P=0.01) than before (46 mmHg; 35-93 mmHg). Carotid augmentation index after HD (22%; 3-30%) was lower (P=0.001) than before (31%; 7-53%). Carotid-femoral pulse wave velocity was not different after HD (8.7 m/s; 5.6-28.9 m/s vs 7.7 m/s; 4.7-36.8 m/s). Aortic compliance after HD (1.10 ml/mmHg; 0.60-2.43 ml/mmHg) was higher (P=0.02) than before (1.05 ml/mmHg; 0.45-1.69 ml/mmHg). The increase in aortic stiffness in HD patients is partly caused by a reversible reduction of aortic compliance due to volume expansion. Volume withdrawal by HD moves the arterial wall characteristics back to a more favourable position on the nonlinear pressure-volume curve, reflected in a concomitant decrease in arterial pressure and improved aortic compliance.

Clinical utility and cost effectiveness of a personal ultrasound imager for cardiac evaluation during consultation rounds in patients with suspected cardiac disease.

OBJECTIVE: To assess the clinical utility and cost effectiveness of a personal ultrasound imager (PUI) during consultation rounds for cardiac evaluation of patients with suspected cardiac disease. METHODS: 107 unselected patients from non-cardiac departments (55% men) were enrolled in the study. After the physical examination the consultant cardiologist performed an echocardiographic study with a PUI. The final report was given instantly to the referring physician. All patients subsequently underwent a study with a standard echocardiographic device (SED). For each patient the consultant cardiologist noted whether the findings of the PUI were adequate for final diagnosis. The total cost when full echocardiography was used was compared with the cost when the PUI was used. The time interval from request to diagnosis was also compared. RESULTS: In 84 (78.5%) patients no further examination with an SED was regarded as necessary. Twenty three patients (21.5%) required a further detailed examination with the SED because of the need for haemodynamic information. There was an excellent agreement for the detection of abnormalities between the two devices (96%). The total cost was euro;132 per patient with the SED and euro;75 per patient with the PUI. According to this study, the use of the PUI can lead to a 33.4% reduction of total cost. The mean time from request to diagnosis at the authors' institution was four days for the SED and instantly for the PUI, for additional potential cost savings. CONCLUSIONS: Immediate echocardiographic assessment during consultation rounds can lead to significant cost savings and can shorten the time to diagnosis.

Second harmonic imaging improves sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease.

OBJECTIVE: Our purpose was to assess the value of second harmonic imaging compared with fundamental imaging for the diagnosis of coronary artery disease during dobutamine stress echocardiography. PATIENTS AND METHODS: Sixty-four patients underwent dobutamine stress echocardiography with both fundamental imaging and second harmonic imaging. Coronary angiography was performed within 3 months. Ischemia was defined as new or worsening wall motion abnormalities in > or = 1 segment during dobutamine stress echocardiography. Coronary artery disease was defined as a > or = 70% luminal diameter stenosis in > or = 1 coronary artery by coronary angiography. RESULTS: There was a higher prevalence of segments with invisible border with fundamental compared with second harmonic imaging both at rest (11% vs 8%, P < .05) and at peak stress (17% vs 10%, P < .001). Significant coronary artery disease was present in 49 (77%) patients. The sensitivity of dobutamine stress echocardiography for detection of coronary artery disease by fundamental and second harmonic imaging was, respectively, 78% and 94% (P < .05), whereas specificity was similar (73% vs 73%). Second harmonic imaging had a particularly higher sensitivity for the diagnosis of 1-vessel disease (93% vs 50%, P < .05). CONCLUSION: The use of second harmonic imaging improves the sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease compared with fundamental imaging, particularly for 1-vessel coronary artery disease, whereas specificity remains unchanged.

Percutaneous transluminal septal myocardial ablation in hypertrophic cardiomyopathy.

BACKGROUND: Percutaneous transluminal septal myocardial ablation (PTSMA) is a new interventional technique to treat patients with hypertrophic cardiomyopathy. METHODS: Small doses of ethanol 96% were injected into a targeted septal artery causing a chemical myocardial infarction. Three patients were evaluated, including a follow-up of three months. RESULTS: There were no complications during the procedure LVOT gradient was reduced from 120±140 mmHg. At follow-up, all three patients showed improvement in validity. CONCLUSION: The method requires an echocardiographic contrast determination of the myocardium at risk for ethanol treatment, in addition to haemodynamic monitoring.

Automated cardiac output measurements by ultrasound are inaccurate at high cardiac outputs.

OBJECTIVE: The sonographic technique of automated cardiac output measurement (ACM) is a promising new method to measure cardiac output and could be of use in a high-risk obstetric unit in the treatment of pre-eclamptic patients. The aim was to determine the accuracy of the ACM method. DESIGN: Comparative study of the sonographic technique of ACM versus cardiac output measured by thermodilution (TD). METHODS: The study included 39 intensive care patients, 21 men, 13 non-pregnant women and five severely pre-eclamptic pregnant patients, with a wide range of cardiac outputs, in whom TD catheters had been inserted for clinical reasons. Two separate experienced observers, blinded to the results obtained with the other method, performed four successive measurements in each patient with either the ACM or TD technique. The averaged cardiac output value per patient and method was used for comparison. RESULTS: Cardiac output was successfully measured with ACM and TD in 85 and 100% of patients, respectively. Mean cardiac output measured by ACM (6.77 +/- 1.90 L/min) was significantly lower than that measured by TD (9.12 +/- 3.06 L/min). Although cardiac output values obtained with ACM were significantly correlated with those measured by TD, the ACM values were consistently lower than TD values in the higher cardiac output range; the relationship was represented by ACM = 0.35 TD + 3.55 L/min (r = 0.57, P < 0.001). The (ACM - TD) difference increased significantly with cardiac output, through a difference in stroke volume, not in heart rate. CONCLUSION: The ACM is not an accurate tool to measure cardiac output in patients with a high cardiac output, including treated pre-eclamptic women.

Optimal rotational interval for 3-dimensional echocardiography data acquisition for rapid and accurate measurement of left ventricular function.

BACKGROUND: Prolonged 3-dimensional echocardiography (3DE) acquisition time currently limits its routine use for calculating left ventricular volume (LVV) and ejection fraction (EF). Our goal was to reduce the acquisition time by defining the largest rotational acquisition interval that still allows 3DE reconstruction for accurate and reproducible LVV and EF calculation. METHODS: Twenty-one subjects underwent magnetic resonance imaging and precordial 3DE with 2 degrees acquisition intervals. Images were processed to result in data sets containing images at 2 degrees, 4 degrees, 8 degrees, 16 degrees, 32 degrees, and 64 degrees intervals by excluding images in between. With use of the paraplane feature, 8 equidistant short-axis slices were generated from each data set. The suitability of these short-axis slices for manual endocardial tracing was scored visually by 4 independent experienced observers. The LVV and EF were calculated by using Simpson's rule from 3DE data sets with 2 degrees, 8 degrees, and 16 degrees intervals, and the results were compared with values obtained from magnetic resonance imaging. The probability of 3DE to detect LVV and EF differences was calculated. RESULTS: All patients were in sinus rhythm with a mean heart rate of 72 bpm (SD + or - 12). The LV short-axis images obtained with 16 degrees rotational scanning intervals allowed LV endocardial tracing in all subjects. Good correlation, close limits of agreement, and nonsignificant differences were found between values of LVV and EF calculated with 3DE at 2 degrees, 8 degrees, and 16 degrees rotational intervals and those obtained with magnetic resonance imaging. At steps of 16 degrees, 3DE had excellent correlation (r = 98, 99, and 99), close limits of agreement (+ or - 38, + or - 28.6, and + or - 4.8), and nonsignificant differences (P =.5,.8, and.2) with values obtained from magnetic resonance imaging for calculating end-diastolic LVV, end-systolic LVV, and EF, respectively. Three-dimensional echocardiography with use of 16 degrees rotational intervals could detect 15-mL differences in end-diastolic volume with a probability of 95%, 11-mL differences in end-systolic volume with a probability of 92%, and 0.02 differences in EF with a probability of 95%. CONCLUSIONS: The 3DE data sets reconstructed with images selected at 16 degrees intervals from data sets obtained at 2 degrees precordial rotational acquisition intervals allowed the generation of LV short-axis images with adequate quality for endocardial border tracing. Therefore precordial acquisition at 16 degrees intervals would be sufficient for the reconstruction of 3DE data sets for LV function measurement. This would reduce the acquisition time while maintaining enough accuracy for clinical decision making and would thus make 3DE more practical as a routine method.

A fast rotating scanning unit for real-time three-dimensional echo data acquisition.

Most three-dimensional (3-D) echocardiography (3-DE) systems today are based on off-line methods where a large number of cross-sectional 2-D scans have to be acquired sequentially before a 3-D image can be reconstructed. Because acquisition is done step-by-step based on ECG triggering plus respiratory gating, this introduces motion artefacts and takes significant acquisition time. Another 3-D approach is based on 2-D transducers and parallel beam-forming. Such a system is very complex. In this manuscript, a fast continuously-rotating scanning unit, based on a 64-element phased-array transducer, is described. Typical rotation speed of the 3-D unit is 8 rotations per s. Therefore, 16 3-D volume datasets can be acquired per s in real-time. The first clinical examples as acquired with this probe are presented.

Appropriate 3-dimensional echocardiography data acquisition interval for left ventricular volume quantification: implications for clinical application.

UNLABELLED: Volume-rendered 3-dimensional echocardiography (3DE) acquired with small imaging intervals has been validated for accurate left ventricular (LV) volume measurement. However, its clinical application is often impeded by the lengthy acquisition time. The aim of this study was to examine the accuracy of LV volume measurement from 3DE data acquired at different intervals. METHODS: Transthoracic 3DE LV data sets were acquired at intervals of 2 degrees, 6 degrees, 9 degrees, 12 degrees, 15 degrees, 18 degrees, and 20 degrees in 10 human subjects with various cardiac shapes and function. The LV end-diastolic volume and end-systolic volume were measured from each 3DE data set with the "summation of disks" method. Interobserver and intraobserver variability were also examined. Measurements obtained from data acquired at 2 degrees intervals were used as references for comparison. RESULTS: From 10 subjects a total of 70 3DE data sets were obtained. Data acquisition time decreased from 189 +/- 143 seconds at intervals of 2 degrees to 19 +/- 6 minutes at 20 degrees. No statistically significant difference was found among the measurements derived from data obtained at various intervals. Excellent agreement was obtained between interobserver and intraobserver measurements. CONCLUSION: Data acquired at 12 degrees and 15 degrees intervals remained accurate for LV volume measurement and saved over 80% of time in comparison with data acquired at 2 degrees intervals. A further increase in imaging intervals tended to underestimate LV volumes without significant acceleration of the procedure.