No abstract

The combination of active catheter tracking and passive real-time visualization in CMR-guided electrophysiologic (EP) studies using advanced interventional hardware and software was safe and enabled efficient navigation, mapping, and ablation. These cases demonstrate significant progress in the development of MR-guided EP procedures.

CMR-EP using active catheter tracking is safe and feasible. The CMR-EP setup provides an effective workflow and has the potential to change the way in which ablation procedures may be performed.

No abstract

A balanced fast field echo (FFE) sequence (also referred to as true fast imaging with steady precession (true FISP)), based on projection reconstruction (PR) is evaluated in combination with real-time reconstruction and interactive scanning capabilities for cardiac function studies. Cardiac image sequences obtained with the balanced PR-FFE method are compared with images obtained with a spin-warp (2D Fourier transform (2DFT)) technique. In particular, the representation of motion artifacts in both techniques is investigated. Balanced PR-FFE provides a similar contrast to spin-warp-related techniques, but is less sensitive to motion artifacts. The use of angular undersampling within balanced PR-FFE is examined as a means to increase temporal resolution while causing only minor artifacts. Furthermore, a modification of the profile order allows the reconstruction of PR images at different spatial and temporal resolution levels from the same data. This study shows that balanced PR-FFE is a robust tool for cardiac function studies. The noninvasive quantification of ventricular function is essential for diagnosing cardiovascular disease and monitoring cardiac changes following an intervention or medical therapy. ECG-gated breath-hold MR-cine techniques are commonly used (1,2). Real-time MRI offers the possibility of assessing ventricular function without ECG-triggering and breath-holding (3-5), and is therefore particularly useful for scanning patients with poor ECGs and for monitoring cardiac function during stress studies. This technique is common in cardiology, and is similar to ventricular function studies performed with ultrasound.Recently, balanced fast field echo (balanced FFE), also referred to as true fast imaging with steady precession (true FISP) (6), has been used successfully to study heart function (7). This technique is also commonly used in interventional MRI at low field strengths (8). In comparison to standard field echo protocols, balanced FFE results in a higher signal-to-noise ratio (SNR) and a higher contrast between myocardium and blood. One general drawback of real-time imaging with spin-warp-related techniques is their sensitivity to motion, which results in ghost-like artifacts. Projection reconstruction (PR) techniques have intrinsic advantages over spin-warp methods with respect to diminished artifacts from motion (9), while showing a similar contrast (10). Motion during scanning results in a pixel blurr and streaking artifacts, which are considered to be more acceptable. Furthermore, PR imaging can be used to increase the temporal resolution by angular undersampling (11).In this work, the intrinsic advantages of PR imaging and the superior contrast of balanced FFE are combined and evaluated in cardiac function studies. Therefore, a balanced PR-FFE sequence is used in combination with a real-time reconstruction and interactive scan capabilities (12). Interactive real-time cardiac scanning was performed on healthy volunteers. Real-time images obtained with the balanced PR-FFE are compared wi...