Cardiovascular magnetic resonance (CMR) tagging has been established as an essential technique for measuring regional myocardial function. It allows quantification of local intramyocardial motion measures, e.g. strain and strain rate. The invention of CMR tagging came in the late eighties, where the technique allowed for the first time for visualizing transmural myocardial movement without having to implant physical markers. This new idea opened the door for a series of developments and improvements that continue up to the present time. Different tagging techniques are currently available that are more extensive, improved, and sophisticated than they were twenty years ago. Each of these techniques has different versions for improved resolution, signal-to-noise ratio (SNR), scan time, anatomical coverage, three-dimensional capability, and image quality. The tagging techniques covered in this article can be broadly divided into two main categories: 1) Basic techniques, which include magnetization saturation, spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), and complementary SPAMM (CSPAMM); and 2) Advanced techniques, which include harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC). Although most of these techniques were developed by separate groups and evolved from different backgrounds, they are in fact closely related to each other, and they can be interpreted from more than one perspective. Some of these techniques even followed parallel paths of developments, as illustrated in the article. As each technique has its own advantages, some efforts have been made to combine different techniques together for improved image quality or composite information acquisition. In this review, different developments in pulse sequences and related image processing techniques are described along with the necessities that led to their invention, which makes this article easy to read and the covered techniques easy to follow. Major studies that applied CMR tagging for studying myocardial mechanics are also summarized. Finally, the current article includes a plethora of ideas and techniques with over 300 references that motivate the reader to think about the future of CMR tagging.

Purpose:To compare the utility of the real-time technique fast strain-encoded magnetic resonance imaging (fast-SENC) for the quantification of regional myocardial function to conventional tagged magnetic resonance imaging (MRI). Materials and Methods:Healthy volunteers (N ϭ 12) and patients with heart failure (N ϭ 7) were examined using tagged MRI and fast-SENC at 3.0T. Circumferential strain was measured using fast-SENC in six endo-and six subepicardial regions in the basal-, mid-, and apical-septum and the basal-, mid-, and apical-lateral wall from the fourchamber view. These measurements were plotted to tagging, in corresponding myocardial segments.Results: Peak systolic strain (Ecc) and early diastolic strain rate (Ecc/second) acquired by fast-SENC correlated closely to tagged MRI (r ϭ 0.90 for Ecc and r ϭ 0.91 for Ecc/second, P Ͻ 0.001 for both). Both fast-SENC and tagging identified differences in regional systolic and diastolic function between normal myocardium and dysfunctional segments in patients with heart failure (for fast-SENC: Ecc ϭ -21.7 Ϯ 2.7 in healthy volunteers vs. -12.8 Ϯ 4.2 in hypokinetic vs. 0.6 Ϯ 3.8 in akinetic/dyskinetic segments, P Ͻ 0.001 between all; Ecc/ second ϭ 104 Ϯ 20/second in healthy volunteers vs. 37 Ϯ 9/second in hypokinetic vs. -16 Ϯ 15/second in akinetic/ dyskinetic segments, P Ͻ 0.001 between all). Quantitative analysis was more time-consuming for conventional tagging than for fast-SENC (time-spent of 3.8 Ϯ 0.7 minutes vs. 9.5 Ϯ 0.7 minutes per patient, P Ͻ 0.001). Conclusion:Fast-SENC allows the rapid and accurate quantification of regional myocardial function. The information derived from fast-SENC during a single heartbeat seems to be superior or equal to that acquired by conventional tagging during several heart cycles and prolonged breathholds.

Using a pre-specified protocol, cardiac and non-cardiac MRIs were performed in CIED patients with pacemaker dependency, abandoned leads, or depleted batteries without occurrence of major adverse events. Patients with devices on advisory need to be monitored carefully during MRI, especially if they are pacemaker dependent.

Purpose: To implement real-time myocardial strain-encoding (SENC) imaging in combination with tracking the tissue displacement in the through-plane direction. Materials and Methods:SENC imaging was combined with the slice-following technique by implementing three-dimensional (3D) selective excitation. Certain adjustments were implemented to reduce scan time to one heartbeat. A total of 10 volunteers and five pigs were scanned on a 3T MRI scanner. Spatial modulation of magnetization (SPAMM)-tagged images were acquired on planes orthogonal to the SENC planes for comparison. Myocardial infarction (MI) was induced in two pigs and the resulting SENC images were compared to standard delayed-enhancement (DE) images. Results:The strain values computed from SENC imaging with slice-following showed significant difference from those acquired without slice-following, especially during systole (P Ͻ 0.01). The strain curves computed from the SENC images with and without slice-following were similar to those computed from the orthogonal SPAMM images, with and without, respectively, tracking the tag line displacement in the strain direction. The resulting SENC images showed good agreement with the DE images in identifying MI in infarcted pigs. Conclusion:Correction of through-plane motion in realtime cardiac functional imaging is feasible using slice-following. The strain measurements are more accurate than conventional SENC measurements in humans and animals, as validated with conventional MRI tagging.

Background: Tissue tagging by cardiovascular magnetic resonance (CMR) is a comprehensive method for the assessment of cardiac regional function. However, imaging the right ventricle (RV) using this technique is problematic due to the thin wall of the RV relative to tag spacing which limits assessment of regional function using conventional in-plane tagging.