Evaluation of the MRI in Measuring the Cardiac Chambers and Thoracic Great Vessels

The ability to obtain accurate cyclical functional information of the cardiac chambers plays a continuing important clinical diagnostic role in the evaluation and monitoring of patients with a wide range of cardiac pathologies, including those embarking on or continuing cardiotoxic chemotherapeutic regimes, as well as patients with lung disease.

The current imaging modalities used for non-invasive imaging of the heart include echocardiography and radionuclide ventriculography. Echocardiographic evaluation of cardiac function is primarily limited to the left ventricle and functional measurements are based on volumetric estimates in turn based usually on geometric assumptions. That is, the volume calculation is based on a limited number of non orthogonal linear measurements assuming a regular (non complex) chamber morphology. This study technique provides no biologic hazard to the patient.

Radionuclide ventriculography does allow for 3D cardiac data acquisition and theoretical evaluation of biventricular function. However, the technique does not provide the same degree of spatial resolution that echocardiography can provide. Radionuclide ventriculography is a commonly accepted diagnostic procedure but does involve use of ionizing radiation.

Magnetic Resonance imaging techniques (of the heart) allows relatively high resolution cross sectional imaging. For example a 512X512 matrix over a 40cm field of view provides in plane resolution better that 1mm. No assumptions are made in regard chamber cross sectional area and hence volume morphology. The slice thickness is determined in advance and may be in the range of 1-10mm. MR data ca be acquired sequentially throughout the cardiac cycle and thus provide a time varying 3D map of the cardiac chambers and related structures during the cardiac cycle.

Inclusion criteria

• Over the age of 18 years
• Able to understand and sign consent without surrogate signature
• Subject weight is within the 300lb limit of the MR scanning table
• Subject's bodily habitus allows the subject to fit within the MR bore
• Subject being able to lie quiescent for a period of up to 60 minutes in a supine position
• Subject would be able to hold breath at times for periods of 15-30 seconds

Exclusion criteria

• Subjects with pacemakers, TENS units, metallic prostheses, metal foreign bodies such as bullets, shrapnel, metallic slivers, shavings or foreign bodies