Cardiac Short Axis Research Articles

An efficient, free-breathing protocol for MR right heart catheterization

Methods The baseline MR examination begins with cardiac localizers. At this stage it is important to verify isocenter because if the patient is too deep in the bore then femoral vascular access sheaths are inaccessible to the operator. Through-plane phase contrast (PC) scans in the ascending aorta and main pulmonary artery follow for quantification of Qp and Qs. To avoid the need to repeat long PC scans (3 averages), we first perform brief PC ‘localizer’ scans with a single average to confirm the selected velocityencoding factor is correct. For cardiac volumetric analysis, long and short axis views are obtained using a real-time SSFP sequence that sacrifices some spatial resolution for increased temporal resolution. Data is collected over one and a half heartbeats to ensure the entire cardiac cycle is captured. Because of the delay in image reconstruction, the short axis stack is acquired last while the operator prepares for catheterization. A dedicated user interface (Interactive Front End, Siemens; Erlangen, Germany) is used for real-time imaging during catheterization. This interface permits interactive manipulation of imaging planes, slice thickness, saturation pre-pulse, and cine loop recordings. To minimize catheterization time, reference images

WE-E-134-11: Ultrasound Cardiac Strain Imaging of Left Ventricle Using Lagrangian Tracking

Purpose: Lagrangian description of myocardial tissue deformation is essential for accurate regional strain estimation of left ventricular wall over time. Failure to couple the estimated displacement and strain information with the correct myocardial tissue structure will lead to erroneous displacement and strain estimation. Methods: In this study, a method to obtain Lagrangian based deformation tracking is presented. Myocardial tissue is divided into a fixed number of pixels whose deformation is tracked over the cardiac cycle. An algorithm that utilizes a polar‐grid generated between the estimated endocardial and epicardial contours for the left ventricle in cardiac short axis images is proposed to ensure Lagrangian description. Displacement estimations from consecutive radiofrequency frames were then mapped onto the polar grid to obtain a distribution of the cumulated displacement that is mapped to the polar grid over time. Results: This method was validated against a finite element analysis (FEA) based canine heart model coupled to an ultrasound simulation program. Segmental analysis of the accumulated displacement and strain over cardiac cycles show excellent agreement between the ideal Results obtained directly from the FEA model and our Lagrangian approach for deformation mapping. Eulerian based estimation results on the other hand, show significant deviation from the ideal Results. A comparison of the displacement and strain estimated on parasternal short axis view on a healthy volunteer is also presented. Conclusion: Lagrangian deformation tracking using a polar grid demonstrates accurate results when validated against finite element cardiac model. In addition to the cardiac application, this approach can also be applied to transverse scans of arteries.

Lagrangian displacement tracking using a polar grid between endocardial and epicardial contours for cardiac strain imaging.

Accurate cardiac deformation analysis for cardiac displacement and strain imaging over time requires Lagrangian description of deformation of myocardial tissue structures. Failure to couple the estimated displacement and strain information with the correct myocardial tissue structures will lead to erroneous result in the displacement and strain distribution over time. Lagrangian based tracking in this paper divides the tissue structure into a fixed number of pixels whose deformation is tracked over the cardiac cycle. An algorithm that utilizes a polar-grid generated between the estimated endocardial and epicardial contours for cardiac short axis images is proposed to ensure Lagrangian description of the pixels. Displacement estimates from consecutive radiofrequency frames were then mapped onto the polar grid to obtain a distribution of the actual displacement that is mapped to the polar grid over time. A finite element based canine heart model coupled with an ultrasound simulation program was used to verify this approach. Segmental analysis of the accumulated displacement and strain over a cardiac cycle demonstrate excellent agreement between the ideal result obtained directly from the finite element model and our Lagrangian approach to strain estimation. Traditional Eulerian based estimation results, on the other hand, show significant deviation from the ideal result. An in vivo comparison of the displacement and strain estimated using parasternal short axis views is also presented. Lagrangian displacement tracking using a polar grid provides accurate tracking of myocardial deformation demonstrated using both finite element and in vivo radiofrequency data acquired on a volunteer. In addition to the cardiac application, this approach can also be utilized for transverse scans of arteries, where a polar grid can be generated between the contours delineating the outer and inner wall of the vessels from the blood flowing though the vessel.

Quantitative contrast‐enhanced first‐pass cardiac perfusion MRI at 3 tesla with accurate arterial input function and myocardial wall enhancement

To develop, and validate in vivo, a robust quantitative first-pass perfusion cardiovascular MR (CMR) method with accurate arterial input function (AIF) and myocardial wall enhancement. A saturation-recovery (SR) pulse sequence was modified to sequentially acquire multiple slices after a single nonselective saturation pulse at 3 Tesla. In each heartbeat, an AIF image is acquired in the aortic root with a short time delay (TD) (50 ms), followed by the acquisition of myocardial images with longer TD values (∼150-400 ms). Longitudinal relaxation rates (R(1) = 1/T(1)) were calculated using an ideal saturation recovery equation based on the Bloch equation, and corresponding gadolinium contrast concentrations were calculated assuming fast water exchange condition. The proposed method was validated against a reference multi-point SR method by comparing their respective R(1) measurements in the blood and left ventricular myocardium, before and at multiple time-points following contrast injections, in 7 volunteers. R(1) measurements with the proposed method and reference multi-point method were strongly correlated (r > 0.88, P < 10(-5)) and in good agreement (mean difference ±1.96 standard deviation 0.131 ± 0.317/0.018 ± 0.140 s(-1) for blood/myocardium, respectively). The proposed quantitative first-pass perfusion CMR method measured accurate R(1) values for quantification of AIF and myocardial wall contrast agent concentrations in 3 cardiac short-axis slices, in a total acquisition time of 523 ms per heartbeat.

Three‐dimensional canine heart model for cardiac elastography

A three-dimensional finite element analysis based canine heart model is introduced that would enable the assessment of cardiac function. The three-dimensional canine heart model is based on the cardiac deformation and motion model obtained from the Cardiac Mechanics Research Group at UCSD. The canine heart model is incorporated into ultrasound simulation programs previously developed in the laboratory, enabling the generation of simulated ultrasound radiofrequency data to evaluate algorithms for cardiac elastography. The authors utilize a two-dimensional multilevel hybrid method to estimate local displacements and strain from the simulated cardiac radiofrequency data. Tissue displacements and strains estimated along both the axial and lateral directions (with respect to the ultrasound scan plane) are compared to the actual scatterer movement obtained using the canine heart model. Simulation and strain estimation algorithms combined with the three-dimensional canine heart model provide high resolution displacement and strain curves for improved analysis of cardiac function. The use of principal component analysis along parasternal cardiac short axis views is also presented. A 3D cardiac deformation model is proposed for evaluating displacement tracking and strain estimation algorithms for cardiac strain imaging. Validation of the model is shown using ultrasound simulations to generate axial and lateral displacement and strain curves that are similar to the actual axial and lateral displacement and strain curves.

An Image-Based Comprehensive Approach for Automatic Segmentation of Left Ventricle from Cardiac Short Axis Cine MR Images

Segmentation of the left ventricle is important in the assessment of cardiac functional parameters. Manual segmentation of cardiac cine MR images for acquiring these parameters is time-consuming. Accuracy and automation are the two important criteria in improving cardiac image segmentation methods. In this paper, we present a comprehensive approach to segment the left ventricle from short axis cine cardiac MR images automatically. Our method incorporates a number of image processing and analysis techniques including thresholding, edge detection, mathematical morphology, and image filtering to build an efficient process flow. This process flow makes use of various features in cardiac MR images to achieve high accurate segmentation results. Our method was tested on 45 clinical short axis cine cardiac images and the results are compared with manual delineated ground truth (average perpendicular distance of contours near 2 mm and mean myocardium mass overlapping over 90%). This approach provides cardiac radiologists a practical method for an accurate segmentation of the left ventricle.

Respiratory and cardiac self‐gated free‐breathing cardiac CINE imaging with multiecho 3D hybrid radial SSFP acquisition

A respiratory and cardiac self-gated free-breathing three-dimensional cine steady-state free precession imaging method using multiecho hybrid radial sampling is presented. Cartesian mapping of the k-space center along the slice encoding direction provides intensity-weighted position information, from which both respiratory and cardiac motions are derived. With in plan radial sampling acquired at every pulse repetition time, no extra scan time is required for sampling the k-space center. Temporal filtering based on density compensation is used for radial reconstruction to achieve high signal-to-noise ratio and contrast-to-noise ratio. High correlation between the self-gating signals and external gating signals is demonstrated. This respiratory and cardiac self-gated, free-breathing, three-dimensional, radial cardiac cine imaging technique provides image quality comparable to that acquired with the multiple breath-hold two-dimensional Cartesian steady-state free precession technique in short-axis, four-chamber, and two-chamber orientations. Functional measurements from the three-dimensional cardiac short axis cine images are found to be comparable to those obtained using the standard two-dimensional technique.

Assessment of ventricular coupling with real-time cine MRI and its value to differentiate constrictive pericarditis from restrictive cardiomyopathy

The purpose of this study was to evaluate the use of respiratory-related ventricular coupling to differentiate patients with constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). In 18 histologically proven cases of CP, 6 patients with inflammatory pericarditis (IP), 15 RCM patients and 17 normal subjects, real-time cine MRI was performed in the cardiac short-axis (basal half of the ventricles) during operator-guided deep respiration. The images were analyzed for ventricular septal position and shape during early ventricular filling. Early diastolic septal inversion (I) or flattening (F) was found in all CP (I:15,F:3), and in all IP (I:2,F:4), but seldom in normals (F:1) and not in RCM. The septal abnormalities occurred at the onset of inspiration and rapidly disappeared with the next heartbeats. The amount of ventricular coupling was evaluated by quantifying the difference in the maximal septal excursion between inspiration and expiration. This parameter, normalized to the biventricular diameter, was significantly larger in CP (20.0+/-4.5%, P<0.0001) and IP (14.8+/-3.2%, P<0.0001) patients than in normals (7.0+/-2.4%), whereas RCM patients had a trend toward decreased excursion (4.2+/-1.7%, P=0.11). A cut-off value of 11.8% (mean normals +2 SD) enabled to differentiate CP patients from normals and RCM patients completely. Real-time cine MRI can easily depict increased ventricular coupling, which may be helpful to better differentiate between CP and RCM patients, especially in patients with normal or minimally thickened pericardium. The increase in coupling in IP patients is likely caused by decreased compliance of the inflamed pericardial layers.

Assessment of ventricular coupling with real-time cine MRI and its value to differentiate constrictive pericarditis from restrictive cardiomyopathy

The purpose of this study was to evaluate the use of respiratory-related ventricular coupling to differentiate patients with constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). In 18 histologically proven cases of CP, 6 patients with inflammatory pericarditis (IP), 15 RCM patients and 17 normal subjects, real-time cine MRI was performed in the cardiac short-axis (basal half of the ventricles) during operator-guided deep respiration. The images were analyzed for ventricular septal position and shape during early ventricular filling. Early diastolic septal inversion (I) or flattening (F) was found in all CP (I:15,F:3), and in all IP (I:2,F:4), but seldom in normals (F:1) and not in RCM. The septal abnormalities occurred at the onset of inspiration and rapidly disappeared with the next heartbeats. The amount of ventricular coupling was evaluated by quantifying the difference in the maximal septal excursion between inspiration and expiration. This parameter, normalized to the biventricular diameter, was significantly larger in CP (20.0+/-4.5%, P<0.0001) and IP (14.8+/-3.2%, P<0.0001) patients than in normals (7.0+/-2.4%), whereas RCM patients had a trend toward decreased excursion (4.2+/-1.7%, P=0.11). A cut-off value of 11.8% (mean normals +2 SD) enabled to differentiate CP patients from normals and RCM patients completely. Real-time cine MRI can easily depict increased ventricular coupling, which may be helpful to better differentiate between CP and RCM patients, especially in patients with normal or minimally thickened pericardium. The increase in coupling in IP patients is likely caused by decreased compliance of the inflamed pericardial layers.

Real‐time cine MRI of ventricular septal motion: A novel approach to assess ventricular coupling

The purpose of this study was to assess the feasibility of magnetic resonance imaging (MRI) to evaluate in real-time, the effects of respiration in ventricular septal motion and configuration in normal volunteers and cardiac patients. Real-time cine MRI studies, using the steady-state free precession (SSFP) technique, were performed in the cardiac short-axis during operator-guided deep inspiration and expiration in normal volunteers (N = 6), and in patients with constrictive pericarditis (CP; N = 6), restrictive cardiomyopathy (RCM; N = 4), chronic cor pulmonale (N = 5), and pericardial effusion. The respiratory effects on septal position and configuration during early ventricular filling were visually assessed. Results were compared with the short-axis breath-hold cine MRI studies, obtained at end-inspiration. In CP patients, onset of inspiration led to a leftward inversion in four of six patients and flattening of the septum in two of six patients during early ventricular filling. Septal abnormalities progressively disappeared during the following heartbeats. A similar pattern was found in one of six patients with pericardial effusion. The above pattern was absent in RCM patients. Although septal flattening during early inspiration was also found in two of six normal volunteers, flattening was minimal compared to that in CP patients. In all cor pulmonale patients, septal flattening or inversion was present, but this was not influenced by respiratory motion. Real-time cine MRI is a promising technique for determining the influence of respiration on septal motion and might be helpful in differentiating between different causes of impaired ventricular filling.

Cleft mitral valve in transposition with intact ventricular septum

We describe two cases of an isolated cleft of the mitral valve in transposition with intact ventricular septum. The cleft is positioned leftward in the pulmonary leaflet, at about 2 o'clock, when viewed from below looking at the cardiac short axis with the right ventricle to one's left hand. Such clefts, when seen in the Taussig-Bing malformation are also positioned leftward. In keeping with our current knowledge of cardiac development, our cases provide further evidence that transposition with an intact ventricular septum is the end-point of the Taussig-Bing spectrum.

Simultaneous measurement of arterial input function and tumor pharmacokinetics in mice by dynamic contrast enhanced imaging: effects of transcytolemmal water exchange.

A noninvasive technique for simultaneous measurement of the arterial input function (AIF) for gadodiamide (Omniscan) and its uptake in tumor was demonstrated in mice. Implantation of a tumor at a suitable location enabled its visualization in a cardiac short axis image. Sets of gated, low-resolution saturation recovery images were acquired from each of five tumor-bearing mice following intravenous administration of a bolus of contrast agent (CA). The AIF was extracted from the signal intensity changes in left ventricular blood using literature values of the CA relaxivity and a precontrast T1 map. The time-dependent 1H2O relaxation rate constant (R1 = 1/T1) in the tumor was modeled using the BOLus Enhanced Relaxation Overview (BOLERO) method in two modes regarding the equilibrium transcytolemmal water exchange system: 1) constraining it exclusively to the fast exchange limit (FXL) (the conventional assumption), and 2) allowing its transient departure from FXL and access to the fast exchange regime (FXR), thus designated FXL/FXR. The FXL/FXR analysis yielded better fittings than the FXL-constrained analysis for data from the tumor rims, whereas the results based on the two modes were indistinguishable for data from the tumor cores. For the tumor rims, the values of Ktrans (the rate constant for CA transfer from the vasculature to the interstitium) and ve (volume fraction of the tissue extracellular and extravascular space) returned from FXL/FXR analysis are consistently greater than those from the FXL-constrained analysis by a factor of 1.5 or more corresponding to a CA dose of 0.05 mmole/kg.

American society of echocardiography guidelines and standards for performance of the fetal echocardiogram

Fetal echocardiography is the ultrasonic evaluation of the human fetal cardiovascular system. General antepartum obstetrical ultrasound has become a standard part of gestational care and is commonly used for the determination of fetal age, size, gender, or well-being and for the detection of congenital anomalies. A variety of maternal or fetal disorders may result in abnormality of the fetal cardiovascular system to a degree which demands evaluation at a level above and beyond that attainable with standard antepartum obstetrical ultrasound. In these circumstances, a fetal echocardiogram should be performed. Improved operator skill amongst physicians performing general antepartum obstetrical ultrasound, in combination with increased sensitivity of present day ultrasound systems, has resulted in improved detection of fetal cardiovascular abnormalities and increased requirements for more detailed evaluation. Congenital heart disease is the most common congenital anomaly found in the human. As the detection rates for congenital anomalies continue to increase, the demand for fetal echocardiography has grown. Accurate diagnosis of congenital heart disease via fetal echocardiography provides many benefits. It allows for a smooth transition between the preand post-natal states, with the opportunity to provide immediate care at birth, thereby avoiding the onset of hemodynamic compromise. Recent

Radiographic and electrocardiographic evaluation of cardiac morphology and function in captive cheetahs (Acinonyx jubatus).

In a prospective study, eight (four males and four females) healthy, adult captive cheetahs (Acinonyx jubatus) were immobilized with a combination of tiletamine-zolazepam (4 mg/kg, i.m.), administered with a remote drug delivery system, to define normal cardiac morphology and function. Standard lateral and ventrodorsal (VD) radiographs were then taken to measure heart and thorax using a metric and vertebral scale system. Standard six-lead electrocardiograms were obtained with the animals in right lateral recumbency under isoflurane anesthesia. Mean chest depth and width was 18.7 +/- 1.3 cm and 13.0 +/- 0.6 cm, respectively. The mean lateral cardiac short axis (X) was 9.1 +/- 0.6 cm. the mean cardiac long axis (Y) was 13.6 +/- 0.7 cm, and the mean lateral heart sum (X + Y) was 22.6 +/- 1.2 cm. In the VD projection, mean cardiac short axis (V) was 10.1 +/- 0.7 cm, mean cardiac long axis (W) was 14.9 +/- 1.2 cm, and the heart sum (V + W) was 24.9 +/- 1.8 cm. The vertebral heart size was 8.2 +/- 0.9. All cheetahs had sinus rhythm, and no arrhythmias were noted. Mean heart rate was 126 +/- 15 beats/min, and the mean electrical axis was 82 + 5 degrees. P waves were always positive on lead II and had a width of 0.04 +/- 0.01 sec and a height between 0.1 and 0.3 mV. PR intervals were 0.11 +/- 0.01 sec. The height of the QRS complex was 1.25 +/- 0.24 mV and the width 0.06 +/- 0.01 sec. The ST segment was 0.04 sec, and the T wave (height: 0.25 +/- 0.05 mV) was positive in all cheetahs examined. Although these cardiac and thoracic measurements were larger than those of domestic cats (Felis catus), ratios of cardiac parameters were similar in both species. Electrocardiographic findings were similar to those reported from domestic cats.

Bestimmung linksventrikulärer Funktionsparameter mittels EKG-gesteuerter Mehrschicht-Computertomographie im Vergleich mit der invasiven Ventrikulographie

To evaluate the accuracy of left ventricular function using a multidetector CT (MDCT) with retrospective ECG-gating and to compare the results with conventional ventriculography. In 26 patients, retrospectively ECG-gated MDCT of the heart (Volume Zoom, Siemens, Germany) as well as conventional coronary angiography including ventriculography was performed to exclude or follow coronary artery disease. CT examination (120 KV, 400 mAs) was carried out with 4 x 1 mm collimation (500 ms gantry rotation time). For CT angiography, 150 ml of contrast media was injected intravenously at a flow rate of 4 ml/s. All data sets of the functional cardiac parameters were reconstructed in end-systolic and end-diastolic phase. End-systolic volume (ESV), end-diastolic volume (EDV) and ejection fraction (EF) were determined from multiplanar reformations orthogonally through the cardiac short axis and analyzed using special evaluation software (ARGUS, Siemens). The results were compared with ESV, EDV and EF obtained from invasive ventriculography. In all cases, a sufficient quality of the MDCT images was achieved. EDV (150.1 +/- 16.2 ml MDCT vs. 138.7 +/- 16.9 ml ventriculography; mean difference 11.4 +/- 12.7 ml; r = 0.51) had an acceptable correlation to conventional ventriculography, and ESV (58.1 +/- 14.6 ml vs. 50.2 +/- 13.4 ml; mean difference 7.9 +/- 8.8 ml; r = 0.81) and EF (60.9 +/- 13.6 % vs. 64.9 +/- 12.7 %; mean difference 4.0 +/- 6.2 %; r = 0.79) showed a good correlation. In comparison with invasive ventriculography, MDCT tended to overestimate significantly EDV (p = 0.008) and ESV (p = 0.003) and to underestimate EF (p = 0.001). MDCT of the heart with retrospective ECG-gating enables efficient estimation of left ventricular function, providing important additional information of non-invasive cardiac imaging using MDCT. However, EDV and EVS were significantly overestimated and EF was underestimated in MDCT compared to ventriculography.

Real-time cardiac cine imaging with SPIDER: steady-state projection imaging with dynamic echo-train readout.

Steady-state projection imaging with dynamic echo-train readout (SPIDER) is a multiecho radial k-space trajectory TrueFISP sequence developed for real-time cine imaging of the heart. This new pulse sequence combines the superior SNR and blood-to-myocardium contrast of TrueFISP with the increased scan time efficiency of EPI and undersampled projection reconstruction. SPIDER sequence RF repetition time (TR) was minimized by limiting the echo-train to a length of three while acquiring the first and third echoes asymmetrically. A temporal resolution of 45 ms was achieved with TR/TE1/TE2/TE3 of 3.24/0.6/1.6/2.6 ms and a factor of 2 view sharing scheme. Phantom experiments showed little difference between the weighting of the signals acquired at each of the echo times but did show considerable off-resonance modulation between them. In vivo experiments demonstrated the feasibility of using the SPIDER sequence for real-time imaging in the cardiac short axis orientation.

Keyhole method for high‐speed human cardiac cine MR imaging

Although electrocardiographic (ECG)-gated magnetic resonance (MR) imaging is widely used for cardiac imaging, it has several disadvantages, such as long imaging time, respiratory artifacts, and motion artifacts induced by arrhythmia. An MR image can be acquired within about 0.3 seconds by using a fast gradient-echo imaging method. When this method is continuously applied, only two to three images can be obtained during a single cardiac cycle. The goal of this study is to obtain cine MR images in a single cardiac cycle using fast gradient-echo imaging combined with the “keyhole” method. The optimal conditions for the keyhole method for cardiac cine imaging were obtained by computer simulation based on a simplified cardiac model. When the read-out direction was set parallel to the cardiac short axis, left ventricular motion was almost correctly reproduced by the keyhole method with acquisition time reduced to one-fourth. J. Magn. Reson. Imaging 1999;10:778–783. © 1999 Wiley-Liss, Inc.

Keyhole method for high-speed human cardiac cine MR imaging.

Although electrocardiographic (ECG)-gated magnetic resonance (MR) imaging is widely used for cardiac imaging, it has several disadvantages, such as long imaging time, respiratory artifacts, and motion artifacts induced by arrhythmia. An MR image can be acquired within about 0.3 seconds by using a fast gradient-echo imaging method. When this method is continuously applied, only two to three images can be obtained during a single cardiac cycle. The goal of this study is to obtain cine MR images in a single cardiac cycle using fast gradient-echo imaging combined with the "keyhole" method. The optimal conditions for the keyhole method for cardiac cine imaging were obtained by computer simulation based on a simplified cardiac model. When the read-out direction was set parallel to the cardiac short axis, left ventricular motion was almost correctly reproduced by the keyhole method with acquisition time reduced to one-fourth. J. Magn. Reson. Imaging 1999;10:778-783.

Left ventricular radial tagging acquisition using gradient-recalled-echo techniques: sequence optimization.

Myocardial tagging with magnetic resonance (MR) imaging offers unique possibilities for noninvasive left ventricular (LV) strain analysis. True three-dimensional strain analysis can be achieved with tags implemented in cardiac short axis and long axis images. Spin-echo (SE) techniques have been used for these studies. However, this approach is time-consuming: images at different phases of the cardiac cycle have to be obtained in successive measurements and hence the total number of measurements equals the number of time frames. Moreover, the images are often degraded by flow and motion artifacts. The purpose of this study was to optimize a faster and more robust MR tagging sequence for use on a clinical whole-body 1 T MR system with optimal persistence of the tags during the entire cardiac cycle. The tagging pulses were implemented in gradient-recalled-echo (GRE) sequences and compared to SE-based acquisitions. The effects of the use of flow-compensating gradients, the excitation angles, and the angles of the saturation pulses have been studied with MR signal simulations and in comparative measurements in volunteers. GRE acquisitions with flow-compensating gradients are robust techniques for myocardial tagging acquisitions. Use of optimized flip angles and saturation pulses can significantly improve delineation of the tag and can be used up to at least 700 ms after the R-wave. Therefore, LV tagging with GRE acquisitions using optimized MR parameters is a robust and promising technique.

MRI-derived ventricular volume curves for the assessment of left ventricular function

To assess the utility of double oblique, ECG-gated 1H magnetic resonance (MR) derived volume curves for assessing LV function, cardiac short axis images were acquired with a fast field echo technique. We applied this methodology to assess left ventricular function in three groups: normals, patients with left ventricular hypertrophy, and dilated cardiomyopathy. Six slices with 16–20 phases per RR interval were analyzed, representing the initial 75–80% of the cardiac cycle. For each slice, the endocardial border of the left ventricular (LV) chamber was manually traced. Using Simpson's rule, the total LV volume at a given phase was determined considering the traced area, thickness and position in three-dimensional space of each of the six constituent slices. The calculated volumes were plotted against time and the stroke volume, ejection fraction and cardiac output were determined. The volume vs time plots for the systolic and diastolic portions of the curve were individually fit to third degree polynomials using a least squares approximation. From the fit curves, the following data were extracted: the mean slope ( dV dT ) during filling and emptying, and the time to 1 4 , 1 3 and 1 2 filling and emptying. These parameters are valuable indices of the functional status of the myocardium; thus, accurate and useful estimates of LV function can be obtained using MRI derived volume curves in normal and abnormal states.