Contrast-enhanced computed tomography (CT) demonstrates all cardiac chambers (right ventricle [RV]; left ventricle [LV]) and metal artifact of internal defibrillator lead (M) in right atrium. Significant wall thinning (arrows) was noted in the apical and lateral LV wall consisting with myocardial infarction (top panels). A matching decrease in signal intensity in apical and lateral wall segments was observed in images obtained with positron emission tomography. Preserved metabolism of papillary muscle (P) was noted. Note the areas of preserved metabolic activity (A) within the lateral wall, which appears uniformly thinned by CT images and may represent surviving myocardium within the infarcted area (middle panels). Positron emission tomographic images are fused with corresponding CT datasets to allow the visualization of metabolic and anatomic datasets. The left ventricular wall is divided into apical (Ap), mid, and basal sections for further analysis with the use of a conventional 17-segment model (bottom panels).

(A) A 3-dimensional voltage map of the left ventricle in different projections. Endocardial voltage is displayed color-coded according to scale. Myocardial scar is shown in red representing voltage of >0.5 mV and appears to extend to the mitral valve (white arrow). (B) Corresponding projections of metabolic 3-dimensional positron emission tomographic metabolic map. A color-coded scale with decreasing metabolic activity from healthy myocardium (orange) to scar (green) demonstrates good correlation with apical-septal-lateral scar defined by voltage mapping. However, a metabolically active area is found at the inferior base (orange-purple area indicated by white arrow), which was not detected with the use of voltage maps and could represent potential ventricular tachycardia channels. Corresponding contrast-enhanced computed tomography demonstrates homogeneous wall thinning along the inferior wall (C, white arrow).

The left ventricle is observed as an ocher-colored reconstruction from basal orientation as indicated by the cardiac icon in the lower left corner. Three-dimensional reconstruction allows the visualization of epicardium but also from endocardium, which can be visualized through the mitral valve plane. Basal, left lateral wall defect is seen as a "hole" in the reconstruction signifying myocardial scar (white arrow, A). A left lateral view allows the visualization of the epicardium with obvious wall defect due to the myocardial scarring described previously (white arrow, B). A right anterior oblique view (B): the "clipping" of the left ventricle allows the visualization of the epicardium and endocardium and demonstrates the corresponding myocardial thickness (En =endocardial surface; Ep = epicardial surface). Myocardial scarring is well visualized as wall defect (white arrow, C). PET = positron emission tomography.

Three-dimensional scar map (purple mesh) is superimposed and registered to endocardial electroanatomic map (solid green) using a visual alignment algorithm. The software of the clinical mapping system displays for each endocardial point the distance to the registered positron emission tomography scar map (green <5 mm, yellow <10 mm, and red >10 mm). Good overall registration quality is seen in right anterior oblique (A), left lateral (B), and apical views (C), displaying green and yellow markers. The only significant registration error (red markers) is found within the area of the apical scar. This error is due to the absence of the positron emission tomography wall in areas of scar (see the Methods section for further explanation), which results in the software measuring the distance to the closest scar border, and does not represent a real registration error. LAT = local activation time.

Apical view displays endocardial voltage map using the conventional voltage criteria for endocardial scar of <0.5 mV displayed in red as seen in the color-coded scale displayed on the right. Superimposed 3-dimensional positron emission tomographic scar map demonstrates a large apical wall defect (hole) in the purple superimposed mesh signifying myocardial scar. Voltage-defined myocardial scar and adjacent area of abnormal myocardial voltage (green and yellow) align well with the area of positron emission tomographic-defined scar after registration. LV = left ventricle.

Endocardial voltage map demonstrates area of continuous lateral scar as defined by classical voltage criteria (red area) with adjacent yellow-to-blue border zone (A). Positron emission tomography-derived 3-dimensional scar map in corresponding view confirms a lateral scar ("hole"; see the Methods section) but demonstrates a bridge of viable myocardium crossing the presumed scar area (white arrow, B). After registration of voltage map and 3-dimensional positron emission tomographic scar map, a bridge of metabolically alive tissue can be seen after successful registration traversing in the middle of the presumed voltage-defined myocardial scar (red, C). RV = right ventricular.

Endocardial voltage map was unable to detect myocardial scar, and all wall segments revealed >1.5 mV voltage (left lateral view, A). However, 3-dimensional positron emission tomographic scar map (ocher shell) reveals a large inferobasal lateral wall defect signifying myocardial scar, which was consistent with the exit site of the presenting ventricular tachycardia (white arrow, B). An epicardial voltage map finally confirmed a large, nontransmural scar (red area, <0.5 mV) in the inferobasal lateral location (white arrow, C). Registration of the epicardial voltage map and 3-dimensional positron emission tomographic scar map demonstrates good correlation between the epicardial voltage-defined scar and the positron emission tomographic-defined scar.