Endomyocardial biopsies (EMB) are an important diagnostic tool in myocarditis, arrhythmias, cardiac tumors, storage disease, cardiac allograft rejection and other cardiac diseases with unknown origin. With DNA and RNA detection EMB evolved into an important diagnostic tool [
1,
2] proposed by the AHA and ACC [
3] as well as ESC [
4]. However, there are concerns about the large sampling error and the adequate clinical setting for biopsies is still in debate. Therefore, in today’s clinical routine multiple (5–6) biopsies are taken from either the left or right ventricle under fluoroscopic guidance with a radiation burden for the patient and the interventionalist. Despite procedural success with overall (major and minor) complication rates from 0% [
5] to 5% [
6,
7] missing the affected myocardium results in a limited diagnostic value providing a diagnostic result in only 25.5% of clinical cases [
6]. Thus, it seems desirable to use a method for visualization of the diseased parts of the heart in order to take directed samples from the affected myocardium. Cardiovascular magnetic resonance (CMR) has a superior soft-tissue contrast compared to X-ray [
8,
9] and allows arbitrary orientation of the imaging plane in three dimensions without exposure to ionizing radiation. Hence, targeted EMB under real-time CMR guidance could solve the sampling problem by reducing the need for multiple biopsies. Nevertheless, interventional CMR has to solve several technical challenges. First, MR-safe and suitable guidewires as well as steerable guiding catheters with distal-tip visualization are mandatory to navigate and reliably reach the affected myocardium. Furthermore, the magnetic field does not allow the use of conventional metallic bioptomes due to heating, magnetization and massive metal artifacts. Until now, MR biopsies are mostly applied in non moving organs like breast [
10], liver [
11], kidney [
12], prostate [
13] or brain [
14] using MR-compatible needles. MR-safe cardiac bioptomes are still not commonly available. Lossnitzer [
15] evaluated a preclinical MR-conditional bioptome in an ex vivo animal heart model. The NIH group [
16] recently demonstrated the feasibility of CMR-guided EMB in an in vivo swine model with extended infarct scars. However, clinically many cardiac conditions are associated with small circumscript lesions rendering targeted biopsies even more challenging. Therefore, we developed an animal model with distinct left ventricular lesions created by controlled radiofrequency ablation. The aim of our study was to show that targeted EMB of focal myocardial lesions is feasible by real-time CMR guidance using a clinical 3T scanner, i.e. that continuous real-time CMR in three dimensions enables a controlled positioning of the guidewire, the guiding catheter, the bioptome and the biopsy itself. Furthermore, we aimed at showing that targeted biopsy has a lower sampling error under real-time CMR compared to fluoroscopically controlled biopsies.