Previous studies have shown that injection of stem/progenitor cells into the border zone of the infarcted area in the context of cardiac regenerative therapy helped to stimulate cardiac repair and protection via cell-to-cell contact and secretion of paracrine factors [
1‐
7]. However, therapeutic effects may rely on the delivery and retention of the regenerative therapeutics on a location where oxygen and nutrients are available to enable survival [
8]. Hence, accurate identification of viable tissue in the proximity of the infarct is of great importance. Via intramyocardial injection catheters stem/progenitor cells or biomaterials can be injected in a minimally invasive fashion into the myocardium. Injection locations can be chosen based on tissue viability measures obtained from electromechanical mapping (EMM), or a-priori knowledge about the infarct location [
9]. The NOGA®XP intramyocardial injection system [
10] provides a three-dimensional (3D) magnetic tracking technology and allows the assessment of local electrical and mechanical tissue characteristics. Local unipolar and bipolar depolarisation potentials and relative catheter tip displacements (linear local shortening) are measured at multiple locations on the left ventricular endocardium. These measurements are interpolated to obtain a three-dimensional reconstruction which is used to guide cell injections. This technique is currently used in clinical practice [
11‐
16]. Measurements can however not, be performed in regions that are susceptible for arrhythmias and measurements are interpolated in regions where no measurements are taken. Furthermore, cut-off values of EMM parameters to identify areas with different viability/perfusion/transmurality vary greatly between studies [
15]. Altogether this approach is not reproducible and prone to errors regarding accurate and detailed identification of the infarct border zone. Since the non-transmural border zone of the infarction is believed to be the preferred delivery site of the stem cell therapeutics [
1], it is crucial for it to be optimally defined during the injection procedure. We hypothesise that combining the gold standard measure of infarct size and location by late gadolinium enhanced magnetic resonance imaging (LGE-MRI) or other MRI techniques [
17] and practical guidance (NOGA®XP) would further optimize the cell delivery location, and lead to a uniform injection strategy. This approach enables accurate selection and targeting of the infarct border zone with a distinct infarct transmurality with a value between 0 and 100 %. In this study we describe the development of a practical software toolbox (3D CartBox) that enables real-time image-guided cell injections. The 3D CartBox registers NOGA®XP catheter positions on pre-procedurally acquired MRI images to perform intramyocardial injections to locations with an a priori identified distinct infarct transmurality. In addition, the 3D CartBox can be used to further specify the definition of border zone of the infarct [
8].