clinical decision making
Delgado, V.
Citation
Delgado, V. (2010, November 11). Novel cardiac imaging technologies : implications in clinical decision making. Retrieved from
https://hdl.handle.net/1887/16139
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Mitral valve morphology assessment:
three-dimensional transesophageal echocardiography versus computed tomography
Ann Thorac Surg in press
Miriam Shanks, Victoria Delgado, Arnold CT Ng, Frank van der Kley, Joanne D. Schuijf, Eric Boersma, Nico R.L. van de Veire, Gaetano Nucifora, Matteo Bertini, Albert de Roos, Lucia Kroft, Martin J. Schalij, Jeroen J. Bax.
26
Chapter
Background: Advances in the minimally invasive mitral valve repair techniques increase the demands on accurate and reliable morphologic assessment of the mitral valve using 3-dimen- sional imaging modalities. The present study compared mitral valve geometry measurements obtained by 3-dimensional transesophageal echocardiography (3D TEE) to those obtained with multi-detector row computed tomography (MDCT) used as a standard reference.
Methods: Clinical pre-operative MDCT and intra-operative 3D TEE were performed in 43 pa- tients (mean age 81.0 ± 7.7 years) considered for transcatheter valve implantation procedure.
Various measurements of mitral valve geometry were obtained from 3D TEE datasets using mitral valve quantification software, and compared to those obtained from MDCT images us- ing multiplanar reformation planes.
Results: Moderate and severe mitral regurgitation was present in 48.9% of patients. There was good agreement in mitral valve geometry measurements between 3-dimensional TEE and MDCT without significant over- or underestimation and tight 95% limits of agreement.
For linear dimensions, angles and areas, the 95% limits of agreement were <1cm, <15º and <2 cm2, respectively. In addition, the intra-class correlation coefficients were >0.8 for all param- eters. Finally, the measurements were highly reproducible with low intra- and inter-observer variability (non-significant over- or underestimation and narrow 95% limits of agreement).
Conclusions: The present study demonstrates the accuracy and clinical feasibility of the as- sessment of the mitral valve geometry with 3D TEE that is comparable to the MDCT measure- ments. 3D TEE and MDCT provide accurate and complementary information in the evaluation of patients with mitral valve disease. Its potential incremental clinical value in the field of tran- scatheter mitral repair procedures needs further assessment in the future studies.
INTRODUCTION
Advances in the percutaneous and surgical options for mitral valve repair have increased the de- mands on accurate and reliable morphologic assessment of the mitral valve. Two-dimensional echocardiography is the most commonly used imaging modality for the assessment of the valvu- lar heart disease. However, the mitral valve has a complex saddle-shaped configuration and its as- sessment by 2-dimensional (2D) imaging techniques may be challenging.1 Significant advances in ultrasound technology have allowed for on-line display of 3-dimensional (3D) images of the mitral valve, contributing to better understanding of the anatomy and geometry of the mitral valve ap- paratus and the spatial relationships with the surrounding cardiac structures. Particularly, the use of newly developed matrix array transesophageal transducers in 3D transesophageal echocardiog- raphy (TEE) has enabled accurate non-invasive imaging of the complex mitral valve anatomy in real time and from unique orientations previously available only to the surgeons.2 Three-dimensional TEE has been shown to be superior to 2D TEE in the evaluation of mitral valve anatomy.3 In addition, multi-detector row computed tomography (MDCT) is increasingly used for non-invasive coronary angiography but also provides high image quality to visualize other cardiac structures.(4) MDCT may provide additional information on the valvular anatomy during the non-invasive evaluation of the coronary vessels.5;6 Recent studies demonstrated that MDCT provides information of the mitral valve anatomy and surrounding structures (coronary sinus and circumflex coronary artery) crucial to anticipate the feasibility of percutaneous mitral valve repair techniques.5-8
Compared to MDCT, 3D TEE can provide complementary information on the valvular structure and function before, during and immediately after mitral valve repair procedures.9;10 Therefore, 3D TEE in combination with MDCT may become the imaging modalities of choice for peri-operative planning of mitral valve disease.
To date, agreements between the 3D TEE and MDCT derived measurements of the mitral valve morphology are unknown. Therefore, the aim of the present study was to compare the geometry measurements of the mitral valve obtained with 3D TEE versus those obtained with MDCT. Off-line analysis of the 3D TEE images was performed with a novel post-processing Mitral Valve Quantifica- tion (MVQ) software (QLAB cardiac 3DQ, Philips Medical System, Andover, MA, USA).
METHODS
Patient population
A total of 43 patients considered for transcatheter valve implantation procedure were prospec- tively included in the present study. Patients with history of mitral valve repair or replacement were excluded. All patients underwent a routine pre-operative 2D transthoracic echocardiogra- phy (TTE) to assess left ventricular and valvular function. MDCT was performed to evaluate aortic and mitral valve anatomy prior to the intervention. In addition, TEE was performed routinely dur- ing the procedure and 3D TEE images of the mitral valve were acquired. The median time interval
between the MDCT and the 3D TEE was 7 days.
Mitral valve geometry was evaluated on 3D TEE and MDCT datasets. Mitral valve geometry pa- rameters were derived during off-line analysis of the 3D TEE images and compared with MDCT mea- surements. The accuracy of the novel MVQ software to assess mitral valve geometry was evaluated using MDCT as a reference method.
The study was conducted with the approval of the Leiden University Medical Center Institu- tional Review Board with specific waiver of the need for individual patient consent.
Two-dimensional TTE
Standard 2D TTE was performed with the subjects at rest in the left lateral decubitus position with a commercially available ultrasound transducer and equipment (M3S probe, Vivid 7, GE-Vingmed, Horten, Norway). All images were digitally stored for off-line analysis (EchoPac version 108.1.5, GE- Vingmed, Horten, Norway). Complete 2D, color, pulsed- and continuous-wave Doppler images were acquired according to standard techniques.11;12 Left ventricular end-systolic volume index and end- diastolic volume index were calculated using Simpson’s biplane method of discs and indexed to body surface area.13 Left ventricular ejection fraction was subsequently derived and expressed as a percentage. Mitral regurgitation severity was determined quantitatively from color Doppler images obtained from the apical 4-chamber views using proximal isovelocity surface area method for deter- mining the effective regurgitant orifice areas and regurgitant volumes as previously described.14
Real-time 3-dimensional TEE data acquisition and analysis
Transesophageal echocardiography was performed using the iE33 ultrasound imaging system (Phil- ips Medical Systems, Andover, MA, USA) equipped with the fully sampled matrix-array TEE trans- ducer (X7-2t) capable of acquiring images in both 2- and 3-dimension. The probe was positioned at the mid-esophageal level at a 120° tilt. Full-volume datasets were obtained using ECG gating over 7 consecutive heart beats to combine 7 small real-time sub-volumes into a larger pyramidal volume.
The scan volume included the mitral apparatus, the aortic valve, and proximal ascending aorta. To avoid stitch artifacts, the images were acquired during a brief suspension of breathing and special care was taken to stabilize the probe during data acquisition.
All images were digitally stored for off-line analysis with the MVQ software (QLAB cardiac 3DQ, Philips Medical System, Andover, MA, USA). MVQ allows precise 3D quantification of the mitral valve geometry and associated structures based on acquired 3D TEE data. MVQ helps to build a 3D model step by step, of the mitral valve annulus, anterior and posterior leaflets, leaflet segmentation, coapta- tion line and potential coaptation defects, as well as mitral valve spatial relationship with the aortic valve. First, 3D images are displayed in end-systole using the multiplanar reformation planes, which allows the operator to crop 3D echocardiographic data sets into infinite planes, and to review the moving image in three simultaneous orthogonal planes. Subsequently, reference points are manu- ally placed on the multiplanar reformation planes. By identifying 3D landmarks on multiplanar refor- mation planes, MVQ builds a 3D model of the mitral valve and the surrounding structures (Figure 1A).
The MVQ 3D model can be manipulated in the 3D space and overlaid on the anatomical 3D view of
the mitral valve. A user-defined 3D measurement set as well as a comprehensive report is generated and displayed. Each measurement can also be displayed on the 3D model (Figure 1B).
The measurements of the mitral valve apparatus performed with the MVQ software included: the in- tercommissural and antero-posterior annular diameters and the mitral annular area, the length, angle and area of the anterior and posterior leaflet, the tenting height and the coaptation leaflet angle and the angle between the mitral annulus and the aortic annulus. Three-dimensional TEE data was ana- lyzed by one experienced observer who was blinded to the results of MDCT data analysis. The 3D TEE parameters were then compared to the measurements obtained from MDCT images (Figure 2).
Multi-detector row computed tomography data acquisition and analysis
In addition, all patients underwent clinically indicated MDCT using 64-detector row or 320-detec- tor row computed tomography scanners (Aquilion64 or Aquilion ONE respectively, Toshiba Medical Systems, Otawara, Japan). Accordingly, data were acquired with a collimation of either 64 x 0.5 mm or 320 x 0.5 mm and a gantry rotation time of 400 ms or 350ms respectively. For the Acquilion64, the tube current was 300 – 400 mA and the tube voltage was 120 kV or 135 kV as determined by patients’ body mass indexes. Similarly for the AcquilionONE, the tube current was 400-580 mA and tube voltage was 100 kV, 120 kV or 135 kV as determined by patients’ body mass indexes. Patient’s heart rate and blood pressure were monitored prior to each scan. Beta-blockers (50- to 100mg me- toprolol orally) were administered in the absence of contraindications if the heart rate exceeded 65 beats/min. All scans were performed during mid-inspiratory breath-hold and 80-90 mL of non-ionic contrast (Iomeron 400, Bracco, Milan, Italy) was injected into the antecubital vein. With a 64-detector row computed tomography scanner, data acquisition was performed gated to the electrocardio- gram to allow retrospective gating and reconstruction of the data at desired phases of the cardiac cycle (at each 10% of RR interval and at 75%-85% for diastole and 30-35% for systole). In contrast, with a 320-detector row computed tomography scanner, prospective ECG triggered dose modula- tion was applied, scanning an entire cardiac cycle and attaining maximal tube current at 75% (when stable heart rate < 60 beats/min) or 65-85% (when heart rate ≥ 60 beats/min) of R-R interval. When prospective dose modulation was used, the tube current outside of the pre-defined interval was 25% of the maximal tube current. Subsequently, data sets were reconstructed and off-line post- processing of MDCT images was performed on dedicated workstations (Vitrea2, Vital Images, Min- neapolis, Minnesota, USA).
Cardiac MDCT images were analyzed by experienced reviewers blinded to the echocardio- graphic results. End-systolic images of the mitral valve, confirmed by visual inspection of the mitral leaflet motion and minimum left ventricular systolic volume, were selected. Using the 3 multiplanar reformation planes, long-axis images analogous to the 120° long-axis view on TEE were obtained (Figure 2). In a manner similar to the 3D TEE image analysis, 2 orthogonal multiplanar reformation planes bisect the long-axis of the left ventricle in parallel. The third transverse plane bisects the mi- tral annulus at the insertion points of the mitral leaflets to obtain the short-axis mitral annular view.
From the long-axis multiplanar reformation plane, tenting height, defined as the distance between the leaflet coaptation and mitral annulus plane,15 as well as the aorto-mitral and the leaflet angles
were obtained (Figure 2). From the short-axis multiplanar reformation plane, the planimetered area of the mitral annulus, the antero-posterior and the intercommisural diameters were obtained. The short-axis plane was then moved parallel to the anterior, and subsequently posterior mitral leaflets, to obtain en face views of the leaflets in which leaflet areas and maximal leaflet lengths were mea- sured (Figure 2).
Statistical analysis
Continuous variables are presented as mean with standard deviation unless stated otherwise. Cat- egorical data are summarized as frequencies and percentages. Bland-Altman plots and calculation of intraclass correlation coefficients were used for agreement analysis between 3D TEE and MDCT derived mitral valvular geometry measurements.16 Good correlation was defined as intraclass cor- relation coefficients >0.8. A 2-tailed p-value < 0.05 was considered significant. Similarly, the intra- observer and inter-observer agreement for 3D TEE and MDCT measurements were evaluated by Figure 1. Real time 3-dimensional transesophageal echocardiography technique for assessment of mitral valve geometry .
Panel A: Using the multiplanar reformation planes, the Mitral Valve Quantification software identifies the land- marks points of the mitral valve apparatus. The anterior, posterior, anterolateral and posteromedial points of the mitral annulus are identified onto the 2- and 3-chamber views. The en face view provides the cross-sectional area of the mitral annulus and simultaneously, the 3D full volume of the mitral valve can be visualized.
Panel B: The software generates a model of the mitral valve and the various parameters can be measured semi- automatically.
Abbreviations: A = anterior; AL = anterolateral; Ao = aorta; LA = left atrium; LV = left ventricle; P = posterior; PM
= posteromedial.
Bland-Altman analysis. All statistical analyses were performed using SPSS for Windows (SPSS Inc, Chicago), version 16.
RESULTS
A total of 43 patients (mean age 81.0±7.7 years; 60% men) were evaluated. Clinical and 2D TTE char- acteristics of the patients are described in Table 1. Mean height, weight, and body mass index were 170.8±7.6 cm, 75.1±10.7 kg, and 25.7±3.4 kg/m2, respectively.
Variable degrees of mitral regurgitation were present in 88.4% of patients, with 48.9% of the pa- tients showing moderate or severe mitral regurgitation (Table 1). The average heart rate during TEE was 66.7±13.3 beats/minute. All patients had good quality 3D TEE and MDCT images suitable for off-line quantification of the mitral valve geometry. The mean values of the parameters describing mitral valve geometry obtained from 3D TEE and MDCT images are shown in Table 2.
There was a good agreement in the mitral valve geometry measurements between 3D TEE and MDCT as demonstrated using Bland-Altman plots (Figures 3-6) and further confirmed by intraclass correlation coefficients > 0.8 for all the parameters (Table 2 and Figure 3-6). No significant over- or underestimations were observed and the 95% limits of agreement were narrow, being within <1cm for distances, <2cm2 for areas and <15° for angles.
Figure 2. Examples of the mitral valve geometry parameters obtained by multi-detector row computer tomography.
From the 3-chamber views, the following measurements were obtained: anterior mitral leaflet angle (panel A);
posterior leaflet angle (panel B); mitral leaflet tenting height (arrow) and coaptation angle (panel C); aorto-mitral annulus angle (panel D). In addition, proper alignment of the multiplanar reformation planes along the mitral leaftlets permits visualization of the sagittal view (3-chamber view, panel E) and the short-axis view at the level of the posterior mitral leaflet (panel F). The length of the posterior mitral leaflet can be measured (panel G), and the posterior mitral leaflet area can be quantified by planimetry (panel H).
Abbreviations: AML = anterior mitral leaflet; Ao = aorta; LA = left atrium; LV = left ventricle; PMLA = posterior mitral leaflet area; PMLL = posterior mitral leaflet length.
Table 1. Baseline clinical and echocardiographic characteristics of the patient population Patients
(n = 43) Clinical characteristics
Age (years) 81.0 ± 7.7
Male/female (%) 26 (60) / 17 (40)
Coronary artery disease (%) 86
Cardiovascular risk factor (%)
Diabetes 44
Hypertension 56
Hypercholesterolemia 54
Current smoking 30
Periferal arterial disease 30
Treatment (%)
Beta-blockers 58
Angiotensin-converting enzyme inhibitors / Angiotensin receptor blockers 70
Statins 74
Diuretics 81
Spironolactone 16
Calcium channel blockers 35
2D echocardiography
Left ventricular ejection fraction (%) 44.9 ± 15.4
Left ventricular end-systolic volume index (ml/m2) 43.8 ± 29.1 Left ventricular end-diastolic volume index (ml/m2) 74.3 ± 31.7
Left atrial volume index (ml/m2) 42.9 ± 12.1
Mitral regurgitation severity (%) None
Mild Moderate Severe
11.6 39.5 41.9 7
Regurgitant volume (ml/beat) 37.7 ± 26.6
Effective regurgitant orifice area (cm2) 0.23 ± 0.16
Abbreviations: 2D = two-dimensional.
Finally, reproducibility of the measurements was assessed in 10 randomly selected patients. Good intra- and inter-observer agreements for mitral valve geometry parameters obtained with 3D TEE and MDCT were observed (Table 3). As assessed with Bland-Altman analysis, there was a good in- tra- and inter-observer reproducibility for all the parameters evaluated without significant over- or underestimation and narrow 95% limits of agreement (Table 3).
Table 2. Agreements in mitral valve geometry measurements obtained with 3-dimensional transesopha- geal echocardiography (MVQ-software) and multi-detector row computed tomography.
Parameter MVQ MSCT
Mitral annular area (cm2) 10.4 ± 2.0 10.3 ± 2.0
Intercommisural annular diameter (mm) 39.7 ± 4.9 41.6 ± 4.5
Antero-posterior annular diameter (mm) 31.6 ± 4.4 29.4 ± 5.1
Anterior leaflet length (mm) 24.1 ± 3.9 23.9 ± 3.1
Posterior leaflet length (mm) 12.2 ± 3.2 13.4 ± 3.3
Anterior leaflet area (cm2) 7.9 ± 1.9 8.0 ± 1.5
Posterior leaflet area (cm2) 4.9 ± 1.6 4.5 ± 1.3
Anterior leaflet angle (º) 24.2 ± 7.7 25.1 ± 7.7
Posterior leaflet angle (º) 37.3 ± 11.3 37.7 ± 9.7
Leaflet coaptation angle (º) 118.7 ± 14.8 120.7 ± 11.9
Aorto-mitral annulus angle (º) 125.1 ± 10.6 122.4 ± 9.2
Tenting height (mm) 9.2 ± 3.1 9.9 ± 3.3
Abbreviations: MDCT = multi-detector row computed tomography; MVQ = mitral valve quantification.
Table 3. Intra- and inter-observer agreements for 3-dimensional transesophageal echocardiography (MVQ-software) and multi-detector row computed tomography.
N = 10 Mean bias (95% limits of agreement)
MVQ MSCT
Parameter Intra-observer Inter-observer Intra-observer Inter-observer Mitral annular area (cm2) -0.5 (-2.0 – 1.0) -0.2 (-1.7 – 1.2) 0.2 (-3.1 – 3.4) -0.2 (-1.3 – 0.7) Intercommisural
annular diameter (mm) -1.2 (-6.1 – 3.8) -0.1 (-2.7 – 2.4) -1.2 (-8.4 – 5.9) -2.3 (-7.5 – 2.8) Antero-posterior
annular diameter (mm) -0.9 (-3.3 – 1.6) -1.3 (-6.5 – 3.9) 0.1 (-7.7 – 8.0) -0.8 (-6.4 – 4.7) Anterior leaflet
length (mm) -2.1 (-9.7 – 5.6) -2.4 (-9.9 – 5.1) 1.2 (-4.3 – 6.7) 0.2 (-2.9 – 3.4) Posterior leaflet
length (mm) -0.4 (-3.3 – 2.4) 0.4 (-3.3 – 4.2) 1.0 (-2.3 – 4.3) 0.0 (-1.7 – 1.7) Anterior leaflet area (cm2) -0.2 (-1.2 – 0.7) 0.5 (-1.5 – 2.6) -0.5 (-4.3 – 3.3) -0.9 (-3.9 – 2.0) Posterior leaflet area (cm2) -0.03 (-0.6 – 0.5) 1.2 (-0.9 – 3.2) 0.3 (-1.0 – 1.7) 0.0 (-0.85 – 0.7) Anterior leaflet angle (º) -1.8 (-5.0 – 1.4) 3.8 (-3.7 – 11.4) 7.0 (-9.8 – 23.9) 1.9 (-6.8 – 10.6) Posterior leaflet angle (º) -0.9 (-6.8 – 5.1) 2.5 (-5.9 – 10.9) 1.4 (-9.6 – 12.4) 1.9 (-3.9 – 7.7) Leaflet coaptation angle (º) 3.5 (-2.6 – 9.8) -5.4 (-17.6 – 6.7) -4.9 (-28.9 – 18.9) -0.8 (-12.6 –10.9) Aorto-mitral annulus
angle (º) 0.8 (-14.1 – 15.6) 5.5 (-17.8 – 28.8) -4.6 (-34.3 – 25.0) -1.3 (-16.4 –13.9) Tenting height (mm) -0.9 (-2.3 – 0.3) -4.2 (-7.6 – -0.8) 2.2 (-4.9 – 9.4) 1.2 (-1.7 – 4.0) Abbreviations: MDCT = multi-detector row computed tomography; MVQ = mitral valve quantification.
Figure 4. Comparison between 3-dimensional transesophageal echocar- diography and multi-detector row computer tomography to measure the mitral anterior leaflet geometry.
Intraclass correlation analysis and Bland-Altman plots demon- strating good agreement in the measurements of the length, area and angle of the anterior mitral leaflet obtained using 3D TEE and MDCT.
Abbreviations: 3D TEE = 3-di- mensional transesophageal echocardiography; ICC = intrac- lass correlation coefficient; MDCT
= multi-detector row computed tomography.
Figure 3. Comparison between 3-dimensional transesophageal echocar- diography and multi-detector row computer tomography to measure the mitral valve annular geometry.
Intraclass correlation analysis and Bland-Altman plots dem- onstrating good agreement in the measurements of the mitral valve annular parameters (inter- commissural and anteroposte- rior diameters and mitral valve annular area) obtained using 3D TEE and MDCT.
Abbreviations: 3D TEE = 3-di- mensional transesophageal echocardiography; ICC = intrac- lass correlation coefficient; MDCT
= multi-detector row computed tomography.
Figure 5. Comparison between 3-dimensional transesophageal echocar- diography and multi-detector row computer tomography to measure the mitral posterior leaflet geometry.
Intraclass correlation analysis and Bland-Altman plots demon- strating good agreement in the measurements of the length, area and angle of the posterior mitral leaflet obtained using 3D TEE and MDCT.
Abbreviations: 3D TEE = 3-di- mensional transesophageal echocardiography; ICC = intrac- lass correlation coefficient; MDCT
= multi-detector row computed tomography.
Figure 6. Comparison between 3-dimensional transesophageal echocar- diography and multi-detector row computer tomography to measure the tenting height, leaflet coaptation and aorto- mitral annular angle.
Intraclass correlation analysis and Bland-Altman plots demon- strating good agreement using 3D TEE and MDCT.
Abbreviations: 3D TEE = 3-dimen- sional transesophageal echo- car dio graphy; ICC = intraclass correlation coefficient; MDCT = multi-detector row computed tomography.
DISCUSSION
The present study demonstrates that 3D TEE allows for an accurate analysis of the mitral valve ge- ometry as compared to the anatomical reference standard MDCT. In addition, 3D TEE derived mea- surements were highly reproducible with good intra- and inter-observer agreements. These find- ings indicate that 3D TEE and MDCT may be complementary imaging tools to evaluate the mitral valve anatomy and geometry.
Three-dimensional analysis of mitral valve anatomy and geometry
Over the last decade, the major advances in the surgical and percutaneous mitral valve repair tech- niques have led to an increasing dependence on the exact morphologic and functional character- ization of the mitral valve as part of pre-operative planning. Two-dimensional echocardiography remains as the mainstay imaging technique to evaluate the geometry and function of the mitral valve. However, 3D imaging techniques provide superior accuracy to assess the dimensions of the mitral valve annulus and mitral leaflet morphology.1;5;17-19 MDCT offers the possibility of 3D acquisi- tion of the entire heart throughout the cardiac cycle and multiple plane reconstructions. The correct alignment of the orthogonal mutliplanar reformation planes permits accurate evaluation of the mi- tral valve anatomy and geometry. Recent studies demonstrated the usefulness of MDCT for the as- sessment of the mitral valve morphology and geometry both in healthy subjects and in heart failure patients with and without functional mitral regurgitation.5 In addition, in a recent series of 112 pa- tients, MDCT demonstrated high sensitivity and specificity to diagnose mitral valve prolapse (96%
and 93%, respectively).20 Finally, the anatomical relationship of the mitral valve apparatus and the surrounding structures such as the circumflex coronary artery and the coronary sinus can be accu- rately evaluated with MDCT.6 Therefore, MDCT permits comprehensive evaluation of patients with mitral valve disease and provides accurate information on mitral valve anatomy and geometry.
The assessment of mitral valve function is also crucial for the clinical decision making of patients with mitral valve disease. In this regard, 3D TEE may be a good complementary imaging tool to MDCT. Several studies have demonstrated that 3D echocardiography has superior accuracy than 2D echocardiography to quantify the severity of mitral valve regurgitation.21;22 In addition, 3D TEE has demonstrated superior accuracy to localize the prolapsed mitral valve scallops as compared to 2D TEE.3;18 Recently, dedicated software has been developed that enabled advanced 3D rendering of the echocardiographic images of the valves, permitting quantitative off-line analysis of the mitral apparatus geometry.17;19;23;24
Initial studies have compared the accuracy of MDCT and 2D TEE to measure the mitral valve annulus.1 However, no studies have performed a direct comparison of the measurements obtained by MDCT to those obtained by 3D echocardiography using this novel post-processing software.
The present study was designed to compare the mitral valve geometry measurements obtained prospectively with MDCT and 3D TEE using MVQ software. There was a good agreement between the two imaging techniques in all the parameters studied with the results being highly reproducible for both methods.
Clinical implications
These technical advances in 3D imaging technology may constitute an important step forward to support the development of new therapeutic approaches for the mitral valve disease. Particularly, the recently introduced minimally invasive surgery or percutaneous mitral valve repair techniques offer a promising therapeutic option for high risk patients with mitral regurgitation who have fa- vorable mitral valve anatomy. These new therapeutic approaches are strongly dependent on ac- curate assessment of the mitral valve anatomy and function and its spatial relationships. For ex- ample, MDCT permits exact location of the coronary sinus relative to the mitral annulus, crucial to determine the feasibility of percutaneous mitral valve annuloplasty.6 In addition, 3D TEE and MDCT identify of the prolapsed scallop of the mitral leaflets, key issue before percutaneous edge-to-edge mitral valve repair technique.3 Therefore, 3D TEE and MDCT may be good complementary imaging modalities to accurately assess mitral valve anatomy, geometry and function. Particularly, 3D TEE permits accurate visualization of the mitral valve apparatus before, during and after the procedure and enables accurate selection of the therapeutic strategy, procedural guidance and evaluation of the immediate results. This may improve the procedural success rate and minimize the number of complications of these novel therapeutic options.25 During the procedure, fluoroscopy remains as the mainstay imaging technique to guide the intervention. However, the poor soft-tissue contrast resolution of fluoroscopy does not permit accurate visualization of the entire mitral valvular appa- ratus. Therefore, the dissemination of these procedures will increase the demand for 3D assessment of the mitral valve. Combination of 3D echocardiography and MDCT assessments may provide the most accurate evaluation of patients with mitral valve disease who are potential candidates to these novel therapies.
Study Limitations
Some limitations should be acknowledged. First, transcatheter or surgical mitral valve repair was not performed in the present population. Therefore, additional studies are warranted to confirm the clinical implications of the current results. Second, MDCT was performed prior to intervention whereas 3D TEE was performed during the intervention.
CONCLUSIONS
In conclusion, the present study demonstrates the accuracy and clinical feasibility of the assess- ment of the mitral valve geometry by 3D TEE that is comparable to the MDCT measurements. Both imaging modalities, 3D TEE and MDCT, provide accurate and complementary information in the evaluation of patients with mitral valve disease. Its potential incremental clinical value in the field of transcatheter mitral repair procedures needs further assessment in the future studies.
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