FIGURE LEGEND
FIGURE 1 Mathematical coordinate system for different imaging modalities
(A) Computed tomography multi-planar reconstruction is based on Cartesian coordinate system. (B) Fluoroscopy is the projection in the direction of image intensifier, which is of spherical coordinate system. Spider view of left coronary artery is yielded from the left anterior oblique (LAO)/ caudal (CAU) projection. (C)Trans-esophageal echocardiography imaging reference plane is similar to the polar coordinate plane in the cylindrical coordinate system. 1-3= spatial orientation of different TEE sectors (1 =Transgastric left ventricular short axis view; 2&3 = Two orthogonal mid-esophageal views); Blue circle = mid-esophageal level; Orange circle = transgastric level; AsAo = ascending aorta; DsAo = descending aorta; LA = left atrium; LAD = left anterior descending artery; LCX = left circumflex artery; LM = left main trunk; LV = left ventricle; LV = left ventricular outflow tract; RV = right ventricle.
FIGURE 2 Methods of stepwise multi-planar reconstruction (MPR) to simulate trans-esophageal echocardiography (TEE) from cardiac computed tomography (CT)
LEFT: Step 1: Invert the z-axis. Eye symbols and colored human models describe the visual perspectives of the CT slices. After obtaining top visual perspective, crosshairs are moved into the esophageal lumen (shorter yellow arrow). Step 2: Turn to the left. On the axial MPR plane (red box), sagittal MPR line is rotated to cross the center of mitral valve. Slight retroflex is added to avoid foreshortening on 4-chamber view (blue box). Steps 3: Rotate. On coronal MPR plane (green box), axial MPR line is rotated to obtain 2-chamber and 3-chamber (long-axis) view. RIGHT: Similarity in configuration is examined by overlaying the yielded CT slices with the corresponded TEE views. ALPM = anterolateral papillary muscle; AsAo = ascending aorta; AV = aortic valve; DsAo = descending aorta; LA = left atrium; LV = left ventricle; MV = mitral valve; PMPM = posteromedial papillary muscle; RA = right atrium; RSPV = right superior pulmonary vein; RV = right ventricle; RVOT = right ventricular outflow tract.
FIGURE 3 Flex to the right
(A) Orange box: Decomposition of trans-esophageal echocardiography (TEE) probe “flex to the right” movement into displacement and negative rotation of the Cartesian coordinate system.(B) Effect of “flex to the right” on mid-esophageal left ventricle 4-chamber view: the left ventricular outflow tract (LVOT) is revealed due to the “negative rotation” component, and is offset with a compensatory positive rotation. (C) Cardiac tomography multi-planar reconstruction simulation. Without “flex to the right”, the line of symmetry of the TEE scanning sector is close to the lateral mitral annulus. As a result, the rotation-yielded bi-commissural view is compromised (left lower green box). With “flex to the right”, the line of symmetry of the TEE scanning sector is displaced toward the center of mitral valve, and the LVOT is again revealed due to the “negative rotation” component. Compensatory positive rotation and rotated degree for bi-commissural view are illustrated with the right lower green box, and better bi-commissural view is obtained. AsAo = ascending aorta; DsAo = descending aorta; Eso = esophagus; LA =left atrium; LV = left ventricle; LV = left ventricle outflow tract; RA = right atrium; RV = right ventricle; RVOT = right ventricular outflow tract; S = spine.
FIGURE 4 Flex to the left with anteflexed echo probe
(A) Orange box: Decomposition of trans-esophageal echocardiography (TEE) probe “flex to the left during anteflex” movement into rotation about the esophagogastric junction and positive rotation of the Cartesian coordinate system. The right colored human models explain the visual perspective of coronal multi-planar reconstruction plane (green box). (B) Effect of “flex to the left during anteflex” on transgastric mitral apparatus view: the left ventricular outflow tract (LVOT) is revealed on the right side. The generated view serves as surrogate image to estimate pressure gradient at LVOT when transgastric LVOT views are not feasible. ALPM =anterolateral papillary muscle; AsAo = ascending aorta; AV= aortic valve; EG junction = esophagogastric junction; LA= left atrium; LAA = left atrial appendage; LPV = left pulmonary vein; LV = left ventricle; LVOT = left ventricular outflow tract; MDCT = multi-detector computed tomography; MPA = main pulmonary artery; MPR = multi-planar reconstruction; MV = mitral valve; PMPM = posteromedial papillary muscle.
FIGURE 5 Mitral apparatus
Blue box: advance and anteflex of the trans-esophageal echocardiography probe to obtain the transgastric left ventricle short-axis view (blue arrow). Green box: Rotation of the multi-planar reconstruction (MPR) line on the coronal MPR plane to obtain the transgastric 2-chamber view for mitral apparatus (green arrow). ALPM = anterolateral papillary muscle; DsAo = descending aorta; LA = left atrium; LAA = left atrial appendage; LCX = left circumflex artery; LPV = left pulmonary vein; LV = left ventricle; MV = mitral valve; PMPM = posteromedial papillary muscle; RA = right atrium; RV = right ventricle.
FIGURE 6 Left ventricular outflow tract
UPPER: Standard deep transgastric 5-chamber view without rotation (0 degree). LOWER: Rotation at 135 degree: from computed tomography orientation cube, we can easily understand the orientation is almost to be that from anterior perspective. AML = anterior mitral leaflet; AsAo= ascending aorta; AV = aortic valve; LA = left atrium; LAA = left atrial appendage; LV = left ventricle; LVOT = left ventricular outflow tract; PA = pulmonary artery; RA = right atrium; RAA = right atrial appendage; RV = right ventricle.
FIGURE 7 Tricuspid leaflets
Interatrial septum avoided at deep esophageal level (yellow box), and tricuspid leaflets investigated without acoustic shadowing. Tricuspid valve and its nearby orientations of nearby cardiac structures are highly variable. As a result, preview with computed tomography multi-planar reconstruction slices can help interventional sonographer to understand better the spatial orientation during procedural trans-esophageal echocardiography imaging. AsAo = ascending aorta; CS = coronary sinus; DsAo = descending aorta; Eso = esophagus; EV = Eustachian valve; IVC = inferior vena cava; LA = left atrium; LV = left ventricle; MB = moderator band; PB = parietal band; RA = right atrium; RCA = right coronary artery; RPV = right pulmonary vein; RV = right ventricle.
FIGURE 8 Tricuspid apparatus
Papillary muscle of anterior tricuspid leaflet is continuous with MB. Several small papillary muscles arising from the diaphragmatic right ventricle wall support the posterior tricuspid leaflet. Ant = anterior tricuspid leaflet; CT = chordae tendineae; D = diaphragmatic right ventricle wall; MB = moderator band; PM = papillary muscle; Post = posterior tricuspid leaflet; RA = right atrium; RV = right ventricle; RVOT = right ventricular outflow tract.
FIGURE 9 Left atrial appendage, aortic valve and interatrial septum
AsAo = ascending aorta; BAV = bicuspid aortic valve; CS = coronary sinus; DsAo = descending aorta; FO = foramen ovale; IAS = interatrial septum; IVC = inferior vena cava; LA = left atrium; LAA = left atrial appendage; PA = pulmonary artery; Pec. m. = pectinate muscles; RA = right atrium; RV = right ventricle; RVOT = right ventricular outflow tract; SVC = superior vena cava; TV = tricuspid valve.