In the last years, cardiac MRI techniques have progressively improved. No other noninvasive imaging modality provides the same degree of contrast and temporal resolution for the assessment of cardiovascular anatomy and pathology. Contraindications MRI are the same as for other magnetic resonance techniques.
The primary advantage of MRI is extremely high contrast resolution between different tissue types, including blood. Moreover, MRI is a true 3 dimensional imaging modality and images can be obtained in any oblique plane along the true cardiac axes while preserving high temporal and spatial resolution with precise demonstration of cardiac anatomy without the administration of contrast media.
Due to these properties, MRI can precisely characterize cardiac function and quantify cavity volumes, ejection fraction, and left ventricular mass. In addition, cardiac MRI has the ability to quantify flow (see flow quantification), including bulk flow in vessels, pressure gradients across stenosis, regurgitant fractions and shunt fractions. Valve morphology and area can be determined and the severity of stenosis quantified. In certain disease states, such as myocardial infarction, the contrast resolution of MRI is further improved by the addition of extrinsic contrast agents (see myocardial late enhancement).
A dedicated cardiac coil, and a field strength higher than 1 Tesla is recommended to have sufficient signal. Cardiac MRI acquires ECG gating. Cardiac gating (ECGs) obtained within the MRI scanner, can be degraded by the superimposed electrical potential of flowing blood in the magnetic field. Therefore, excellent contact between the skin and ECG leads is necessary. For male patients, the skin at the lead sites can be shaved. A good cooperation of the patient is necessary because breath holding at the end of expiration is practiced during the most sequences.

See also Displacement Encoding with Stimulated Echoes.
For Ultrasound Imaging (USI) see Cardiac Ultrasound at Medical-Ultrasound-Imaging.com.

See also the related poll results: 'In 2010 your scanner will probably work with a field strength of' and 'MRI will have replaced 50% of x-ray exams by'

A pacemaker is a device for internal or external battery-operated cardiac pacing to overcome cardiac arrhythmias or heart block. All implanted electronic devices are susceptible to the electromagnetic fields used in magnetic resonance imaging. Therefore, the main magnetic field, the gradient field, and the radio frequency (RF) field are potential hazards for cardiac pacemaker patients.
The pacemaker's susceptibility to static field and its critical role in life support have warranted special consideration. The static magnetic field applies force to magnetic materials. This force and torque effects rise linearly with the field strength of the MRI machines. Both, RF fields and pulsed gradients can induce voltages in circuits or on the pacing lead, which will heat up the tissue around e.g. the lead tip, with a potential risk of thermal injury.
Regulations for pacemakers provide that they have to switch to the magnet mode in static magnetic fields above 1.0 mT. In MR imaging, the gradient and RF fields may mimic signals from the heart with inhibition or fast pacing of the heart. In the magnet mode, most of the current pacemakers will pace with a fix pulse rate because they do not accept the heartsignals. However, the state of an implanted pacemaker will be unpredictable inside a strong magnetic field. Transcutaneous controller adjustment of pacing rate is a feature of many units. Some achieve this control using switches activated by the external application of a magnet to open/close the switch. Others use rotation of an external magnet to turn internal controls. The fringe field around the MRI magnet can activate such switches or controls. Such activations are a safety risk.
Areas with fields higher than 0.5 mT (5 Gauss Limit) commonly have restricted access and/or are posted as a safety risk to persons with pacemakers.

A Cardiac pacemaker is because the risks, under normal circumstances an absolute contraindication for MRI procedures.
Nevertheless, with special precaution the risks can be lowered. Reprogramming the pacemaker to an asynchronous mode with fix pacing rate or turning off will reduce the risk of fast pacing or inhibition. Reducing the SAR value reduces the potential MRI risks of heating. For MRI scans of the head and the lower extremities, tissue heating also seems to be a smaller problem. If a transmit receive coil is used to scan the head or the feet, the cardiac pacemaker is outside the sending coil and possible heating is very limited.

During the MRI scan an augmentation of T waves is observed at fields used in standard imaging but this possible MRI side effect is completely reversible upon removal from the magnet. A field strength dependent increase in the amplitude of the ECG in rats has been observed during exposure to high homogeneous stationary magnetic fields, but this side effect is not transferable to standard imaging situations for humans.

The minimum level at which augmentation can be observed is 0.3 T and increases by higher field strength. An augmentation in T-wave amplitude can occur instantaneously and is immediately reversible after exposure to the magnetic field ceased. There should be no abnormalities in the ECG in the later follow-up. Augmentation of the signal amplitude in the T-wave segment may result from superimposed electrical potential. No circulatory alterations coincide with the ECG changes. Therefore, no biological risks are believed to be associated with them.

For more MRI safety information see also Contraindications and MRI Risks.

Quick Overview
Please note that there are different common names for this artifact.

This artifact appears as a bright spot (or zipper line) in the image center. Central point artifacts are caused by a DC offset in the hardware. MRI scanners normally offer a software compensation (DC correction, baseline correction) for prevention.

Take care for a constant temperature. If the problem increases or keeps on existing, it should be addressed to the service.

Contrast enhanced MRI is a commonly used procedure in magnetic resonance imaging. The need to more accurately characterize different types of lesions and to detect all malignant lesions is the main reason for the use of intravenous contrast agents.
Some methods are available to improve the contrast of different tissues. The focus of dynamic contrast enhanced MRI (DCE-MRI) is on contrast kinetics with demands for spatial resolution dependent on the application. DCE-MR imaging is used for diagnosis of cancer (see also liver imaging, abdominal imaging, breast MRI, dynamic scanning) as well as for diagnosis of cardiac infarction (see perfusion imaging, cardiac MRI). Quantitative DCE-MRI requires special data acquisition techniques and analysis software.
Contrast enhanced magnetic resonance angiography (CE-MRA) allows the visualization of vessels and the temporal resolution provides a separation of arteries and veins. These methods share the need for acquisition methods with high temporal and spatial resolution.
Double contrast administration (combined contrast enhanced (CCE) MRI) uses two contrast agents with complementary mechanisms e.g., superparamagnetic iron oxide to darken the background liver and gadolinium to brighten the vessels. A variety of different categories of contrast agents are currently available for clinical use.
Reasons for the use of contrast agents in MRI scans are:
Common Indications:
Brain MRI : Preoperative/pretreatment evaluation and postoperative evaluation of brain tumor therapy, CNS infections, noninfectious inflammatory disease and meningeal disease.
Spine MRI : Infection/inflammatory disease, primary tumors, drop metastases, initial evaluation of syrinx, postoperative evaluation of the lumbar spine: disk vs. scar.
Breast MRI : Detection of breast cancer in case of dense breasts, implants, malignant lymph nodes, or scarring after treatment for breast cancer, diagnosis of a suspicious breast lesion in order to avoid biopsy.

For Ultrasound Imaging (USI) see Contrast Enhanced Ultrasound at Medical-Ultrasound-Imaging.com. See also Blood Pool Agents, Myocardial Late Enhancement, Cardiovascular Imaging, Contrast Enhanced MR Venography, Contrast Resolution, Dynamic Scanning, Lung Imaging, Hepatobiliary Contrast Agents, Contrast Medium and MRI Guided Biopsy.