CMR-guidance of passively tracked endomyocardial biopsy in an in vivo porcine model.

Endomyocardial biopsy (EMB) is considered to be the diagnostic gold-standard in detection of myocardial-inflammation. EMB is usually conducted under fluoroscopy without any specific target information. Specific target-information provided by cardiovascular magnetic resonance (CMR) may improve specificity of EMB. The aim was to investigate feasibility and safety of CMR-guided and targeted EMB in a preclinical-model using passively-tracked devices. Procedures were performed on a MRI-System equipped with an Interventional Software-Platform for real-time imaging. Ex vivo experiments were conducted to optimize visibility of the guide-sheath. In vivo experiments were conducted in 2 pigs for technical feasibility assessment and in 4 pigs after acute myocardial infarction to test feasibility of guided and lesion targeted EMB. For anatomical real-time imaging a single-shot-balanced-SSFP-sequence was applied. Myocardial targets were identified under real-time imaging (single-shot-T2 (sshT2) and single-shot Late-Gadolinium-Enhancement (sshLGE) sequences). Ex vivo experiments demonstrated best visibility of continuously labelled guide-sheath. CMR-guided EMB was feasible in all cases without major complications. Likewise, lesion-targeting endomyocardial biopsy was feasible in two cases. Biopsies exhibited appropriate sizes and qualities. Real-time lesion sequences revealed comparable CNR values to clinical-protocols. Real-time imaging of lesions showed following signal- and contrast-to-noise ratios (SNR/CNR): SNR of sshT2- and sshLGE was 124 ± 35 and 67 ± 51 respectively, whereas CNR was 81 ± 30 and 57 ± 44. This study demonstrates feasibility and safety of CMR-guided and basically targeted EMB with passively-tracked devices. Signal-to-noise ratios of real-time sequences is non-inferior to standard sequences for lesion detection. CMR-guidance may improve diagnostic accuracy of EMB since CMR can detect myocardial-targets under real-time-imaging.

Magnetic resonance guided renal denervation using active tracking: first in vivo experience in Swine.

Interventional cardiovascular magnetic resonance (iCMR) might evolve as a technique to improve procedural success rates in cardiovascular interventions by combining intraprocedural guidance and simultaneous lesion imaging. The objective of the present study was to prove feasibility and estimate safety of renal sympathetic denervation guided by real-time iCMR using active tracking. Six pigs were examined in a 1.5 T MRI-System (Achieva, Philips Healthcare, Best, Netherlands) equipped with non-invasive hemodynamic control and in-room monitors displaying an interventional software platform [Interventional MRI Suite (iSuite), Philips Research, Hamburg, Germany]. MR-guided renal denervation was performed using a MR conditional non-irrigated ablation catheter with active tracking (Imricor, Burnsville, MN, USA). Real-time imaging for device guidance was performed with a TFE sequence, vessel patency was assessed with a 3D non-contrast angiography and velocity encoded imaging. Oedema of the renal artery was visualized by a high-resolution T2 SPIR sequence. Renal sympathetic denervation was feasible in all cases with survival of all animals. Non-contrast angiography displayed renal artery patency accompanied by equal flow conditions before and after the ablation in all cases as measured by velocity encoded imaging. Oedema imaging displayed a significant increase in relative signal intensity at renal artery ablations sites pre and post intervention (p < 0.05). The histologic examination revealed no signs of perforation or bleeding, while sufficient ablation lesions could be depicted. MR-guided renal sympathetic denervation using active tracking is feasible and the initial data suggest safety of this procedure. MR-guided renal sympathetic denervation offers the inherent strength of high soft tissue contrast thereby providing target information without the use of iodinated contrast agents or radiation.

[Cardiovascular magnetic resonance imaging: importance in coronary artery disease]. / Kardiovaskuläre Magnetresonanztomographie: Stellenwert bei koronarer Herzerkrankung.

Cardiovascular magnetic resonance imaging (MRI) has the ability to assess the morphology, function, perfusion and evidence of myocardial scar tissue in a single examination. Moreover, cardiovascular MRI can be carried out with no exposure to radiation. Stress MRI can be performed by assessment of dobutamine-induced wall motion abnormalities or by first-pass adenosine perfusion imaging. Compared to stress echocardiography or single photon emission computed tomography, stress MRI is at least as accurate; however, patients with ferromagnetic materials or other contraindications for MRI, such as intolerance of gadolinium contrast agents cannot be examined. The quality of stress MRI depends on where the examination is being performed and should always be regarded in context to other clinical information, such as from patient history and electrocardiography.