Journal o f the American Society o f Echocardiography Vo lume 8 N u m b e r 3 Abstracts 343

3 - I I 3D E C H O A S S E S S M E N T O F R I G H T V E N T R I C U L A R V O L U M E AND E J E C T I O N F R A C T I O N IN P A T I E N T S : C O M P A R I S O N T O M A G N E T I C R E S O N A N C E AND G A T E D B L O O D P O O L R A D I O N U C L I D E I M A G I N G

Howard D. Apfel, MD, Aasha S. Gopal MD, Zhanqing Shen MD, Lawrence M. Boxt MD, Jose Katz MD, Robyn J. Barst MD Lindsey D. Alan MD, Dona d L. King MD. Columbia University, NY, NY, Assessment of RV size and function is important for management of pulmonary hypertension and congenital heart disease. The complex shape of the RV limits use of 2D echo methods for this purpose. 3D echo eliminates the need for geometric assumptions. We have adapted to the RV a 3D echo method p r e v i o u s l y validated for LV reconstruction. Purpose: To compare 3D echo estimates of RV volume and EF to those obtained by magnetic resonance imaging (MR]) and gated blood pool radionuclide imaging (MUGA) in patients with a wide range of RV volumes and function. Method: 17patients (6 males, 8 females, ages 2-20y; 3 ntales ages 24, 34, and 42y) with pulmonary hypertension were studied by 3D echo, MRI and MUGA. For 3D echo, 8-10 parasternal short axis images are used to sample the RV from the puLmonic valve to the apex. These images are not parallel or evenly spaced and do not intersect in the region of interest. Diastolic and systolic volumes were computed by surface reconstruction and compared to MRI results obtained using a previously validated gradient reversal short axis acquisition technique. Statistical analysis was by linear regression and the Bland-Altman method.

MR] vs. 3D: n=17, range: EDV=4,I-31Oml; ESV=23-230ml r regression equation SEE Bias Limits

EDV 0.97 3D=-3.8+(0.72)MRI 16.7ml -46.2ml 61. lml ESV 0.98 3D=-l . l+(0.72)MRI l l .7ml -28.2ml 46.9ml

MRI EF: n=16 range=21-64% EF r regression equation SEE Bias Limits

3D 0.88 3DEF=6.7+(0.81)MRI 5.9% -0.88% 12.4% MUGA 0.61 MUGA=14.6+(0.6)MRI 10.4% -1.69% 22.6%

Conclusions: Preliminary results show an excellent correlation and small SEE of 3D echo RV volumes and EF with MRI, 3D echo estimates of RV EF are comparable to MRI and superior to MUGA. There is a 3D echo bias underestimating MR[ volumes due to the antenor position of the RV and the narrow sector view afforded by the transducer in the near field. This combination of factors results in exclusion of some margins of the RV. This current limitation may be corrected by using alterhate transducer designs.

5 - I I Application in Patients of a New Simplified System for 3D-Echo Reconstruction of the Left Ventricle. Donato Mele, *Jargen Maehle, Claudio Pratola, Igino Pedini, Paolo Alboni, "Robert A. Levine. Ospedale Civile, Cento, Italy; *Dept. of Engineering, Trondheim University, Norway; ~ General Hospital, Boston.

A simplified practical approach to 3D reconstruction of the left ventricle (LV) uses a minimum number of apical views spanning the LV and fits a surface to the traced endocardial borders by a bicubic spline algorithm. This system has been previously validated in vitro by our group but little quantitative information is available in humans. The aim of this work was to validate the quanfitafive accuracy of such a system for calculafinq stroke volume (SV) in the clinical set~n,q. 40 healthy subjects (age 26 + 7 yrs; group A) and 20 pafients with LV dyskinesis or aneurysm (age 63 + 6 yrs; group B) were studied and three standard apical views were used for reconstruction. Results were compared with Doppler SV (as an independent noninvasive measure; mean of aortic and mitral flows). SV was also calculated by 2D apical methods currently used (monoplane area-length, monoplane and biplane Simpson's). In the final 15 individuals (10 group A, 5 group B) reconstruction was performed varying the angular relationship between the 2D views and also applying a special algorithm that stretches the endocardial traces to compensate for potential foreshortening of the views, RESULTS: 3D SVs correlated well with Doppler $Vs both in group A (y=1.O2x-1.4, r=,97, SEE=3.5 ml) and in group B (y=O.86x+8.3, r=,89, SEE=4.1 ml). Interobserver variability was 2.6 ml (4.3% of the mean). The 2D apical methods gave lower correlations (r=.90-.91 group A; .63-,78 group B) and greater standard errors (SEE=6.3- 6.6 ml group A; 7.1-11.2 ml group B, p<,01). Variation of the input angles of the views and border stretching produced only minimum variations (1.6% of the mean for stretching). CONCLUSIONS: This 3D method accurately calculates SV in patients and is more accurate than 2D methods in both normal and asymmetric LVs. It has the advantage of being easy and rapid (3-5 rain) and therefore should be particularly useful in routine clinical echo to assess SV in LV remodelling.

4 - I I A NEW METHOD OF 3-DIMENSIONAL RECONSTRUCTION AND QUANT1TATION OF THE MITRAL ANNULUS, VALVE, AND LEFT VENTRICLE : I N VITRO VALIDATION.

ME Logger MBChB, G Bashein MD PhD, JA McDonald PhD, RW Martin PhD, FH Sheehan MD, X-N Li MD, E Bolson MS, F DeRook MD, CM Otto MD. University of Washington, Seattle, Washington.

The functional interrelationship of the complex structure of the mitral apparatus and the left ventricle (LV) is best analyzed in 3 dimensions, but the ability to perform quantitative 3-dhnansional (3D) measurements requires careful in vitro validation. This study assessed the accuracy of a new method of 3D reconstruction of the mitral annulus, valve, and left ventricle. Nine phantoms mimicking the saddle-shaped mitral annulus, the valve leaflets, and LV were scanned with an omniplane transesophageal (TEE) probe, using a rotational scanning technique. Images were acquired every 5 ~ from 0-180 ~ through the mitral annulus in the long axis of the LV to mimic a transatrial position in vivo. The annulus, valve leaflets, and vantricular borders were manually outlined. The LV and valve leaflets were reconstructed by fitting a piecewise-smooth subdivision surface using non-linear least squares optimization. The mitral annulus was fitted to the data with 5-harmonic Fourier series in each of the three spatial coordinates, using the point-to-point path Iength as the independent variable. A least squares plane was fitted to the base of the phantom opposite to the annulus, and the minimum (min.AD) and maximum annular deviation (max.AD) were estimated as the distance from the basal plane. The annular area was calculated from the annular points as projected onto the basal plane. Linear regression of the reconstructed areas, lengths and volumes compared with actual dimensions are shown :

Range R' SEE S lope Intercept Annular area (cm ~) 15.5-44.1 0.997 0.5 1.02 -0.78 Annular length (cm) 15.2-26.3 0.980 0.5 1.09 -0.58 Max. AD (cm) 3.8-7.6 0.992 0. I 1.04 -0.30 Min. AD (era) 3.2-6.i 0.989 0.1 0.88 0.50 Anterinrleaflet (cm 2) 10.1-32.4 0.980 1.O 1.05 -0.45 Postarinrlcaflet (cm 2) 5.9-14.6 0.870 1.1 0.80 1.57 LV volume (ml) 48.3-151.2 0.991 3.5 1.05 -0.59 Conclusion: With this technique, accurate and precise linear, area, and volu- metric measurements of the mitral apparatus and LV are achievable. These methods could be applied clinically to perform quantitative 3D analysis of mitral annular and valve mechanics in patients with mitral valve dysfunction.

6 - I I Quantitative Transthracic Three-dimensional Voxel Imaging of the Left Ventricle in Normal Children and Adolescents Myung-Yong Lee, Leng Jiang, Dan Gilon, Michael d. A. Williams, Richard M. Derman, Arthur E. Weyman, Robert A. Levine, Mary Etta King, Massachusetts General Hospital, Boston, MA

Recent computational advances have permitted 3-dimensional (3D) reconstruction of echo intensities over the cardiac volume from rotated 2D views gated to ECG and respiration. Unlike approaches using selected 2D echo images, such automated voxel acquisitions conveniently provide rapid spatial appreciation in animated views from multiple perspectives. However, only limited data are available regarding the accuracy of such reconstructions in patients, particularly using the Iransthoracic approach without the need for TEE. We therefore studied the left ventdcles of 21 normal children and adolescents (6-19 years old) by transthoracic apical rotation, in order to compare calculated stroke volumes with an independent noninvasive measure. Endocardial borders in parallel cross-sections derived from the 3D voxel data were traced, and volumes calculated as ~ (cavity area X slice height). Stroke volumes were compared with Doppler values (mean of mitral inflow and aortic outflow, in the absence of regurgitation). Results: Coherent LV reconstructions could be obtained in 19/21 subjects, limited by patient motion in the other 2. in the 19 reconstructed ventricles, stroke volumes agreed well with Doppler values: y=.94x+l.14, ~.96, SEE=5.11 cc and mean en'or=3.6%. Conclusions: 3D volumetric reconstruction of the LV not only provides convenient gated acquisition and ready spatial appreciation from multiple perspectives, but is also quantitatively accurate for left ventricular stroke volume and therefore cardiac output in human studies by the transthoracic approach. These results support the use of this technique to address clinical and research questions.