MR imaging in assessing cardiovascular interventions and myocardial injury

Abstract

Performing an MR-guided endovascular intervention requires (1) real-time tracking and guidance of catheters/guide wires to the target, (2) high-resolution images of the target and its surroundings in order to define the extent of the target, (3) performing a therapeutic procedure (delivery of stent or injection of gene or cells) and (4) evaluating the outcome of the therapeutic procedure. The combination of X-ray and MR imaging (XMR) in a single suite was designed for new interventional procedures. MR contrast media can be used to delineate myocardial infarcts and microvascular obstruction, thereby defining the target for local delivery of therapeutic agents under MR-guidance. Iron particles, or gadolinium- or dysprosium-chelates are mixed with the soluble injectates or stem cells in order to track intramyocardial delivery and distribution. Preliminary results show that genes encoded for vascular endothelial and fibroblast growth factor and cells are effective in promoting angiogenesis, arteriogenesis, perfusion and LV function. Angiogenic growth factors, genes and cells administered under MR-guided minimally invasive catheter-based procedures will open up new avenues in treating end-stage ischemic heart disease. The optimum dose of the therapeutic agents, delivery devices and real-time imaging techniques to guide the delivery are currently the subject of ongoing research. The aim of this review is to (1) provide an updated review of experiences using MR imaging to guide transcatheter therapy, (2) address the potential of cardiovascular magnetic resonance (MR) imaging and MR contrast media in assessing myocardial injury at a molecular level and labeling cells and (3) illustrate the applicability of the non-invasive MR imaging in the field of angiogenic therapies through recent clinical and experimental publications.

Identification and differentiation of magnetically labeled mesenchymal stem cells in vivo in swines with myocardial infarction

“…To address these important issues, molecular markers capable of tracking transplanted cells and determining the fate of engrafted cells would be extremely useful. Cells labeling with MR contrast media were used as a new technology to monitor the in vivo behavior of MSCs [3]. In the current study, we use the realtime tracking technology, MR imaging, to determine whether labeled MSCs indeed migrate into injured regions and further differentiate into cardiomyocytes after transplantation.…”

Myocardial infarction quantification with Manganese‐Enhanced MRI (MEMRI) in mice using a 3T clinical scanner

“…For the Mn 2þ dose study and infarction quantification, segmentation was done by manually drawing a region of interest (ROI) in septum area, myocardial infarction (MI) or free wall. The mean ROI size was 1.22 AE 0.51 mm 2 . The free wall ROI was chosen to be in the same myocardial area for the control and sham-operated groups as for the IR60 group.…”

“…In cardiac magnetic resonance imaging (MRI), extracellular contrast agents such as various gadolinium (Gd 3þ ) chelates, are now routinely used in clinical practice, as well as in research protocols to assess myocardial perfusion or interstitial space remodeling (1)(2)(3). Intracellular MR contrast agents can provide additional information on the cellular metabolism.…”

Gd loading by hypotonic swelling: an efficient and safe route for cellular labeling

“…(G) T 2w and T 1w MR images of a phantom containing Gd–HPDO3A labeled‐J774A.1 cellular pellets. The phantom contains the following samples: cells having undergone the ‘osmotic‐shock’ labeling procedure in the presence of increasing concentrations of Gd–HPDO3A in the hypotonic medium (30, 50, 70 or 100 m m ); unlabeled J774A.1 cells; water. (H) Amount of internalized Gd–HPDO3A per cell for K562 cells by changing the temperature of swelling and/or resealing steps.…”