1) Describe the approach of cardiac MR and CT in assessment of cardiac function and size. 2) Understand potential differences between varies imaging strategies. 3) Understand the impact and role of cardiac size and function on treatment decisions.
Introduction:
The cardiac performance is generally assessed by volumetric quantifications such as size and output allowing categorization and comparison of the functional status. Follow-up and changes over time may allow identification of early disease onset, may trigger specific therapies and may allow prediction of patient prognoses and general outcome.
While CT and MRI imaging provide more accurate results echocardiography remains the primary choice. The added radiation burden of cardiac CT I functional analysis has to be kept in mind and CT therefore should only be considered a 3rd line option.
Methods:
Most important measures of systolic cardiac function are end-diastolic volume (EDV), stroke volume (SV), ejection fraction (EF) and cardiac output/cardiac index. While echocardiography is limited by the acoustic window, CT and MRI can easily cover all aspects of the atria and ventricles. While clinically performed echocardiography often only provides a categorization of ventricular EF (grade 1-4) with large variations related to various geometric models that especially fail in regional dysfunction, CT and MRI allow to maintain accuracies despite underlying pathologies. In order to maintain high accuracy/low variability the selection of adequate imaging parameters with respect to coverage, spatial resolution and temporal resolution is required. Today’s functional cardiac MR imaging is almost exclusively performed using cine SSFP methods with cardiac short axis oriented imaging for the left ventricle and short axis or transverse orientation for the right ventricle. Atrial volumetric assessment is performed rarely but might especially be of interest in patients with AV valve dysfunction or atrial sources of arrhythmia.
Conclusion
Based on its accuracy cardiac MR plays an increasingly important role in assessment of patients with cardiac diseases. Accurate and precise quantification of cardiac function is increasingly important in various therapy decisions.
Wintersperger, B,
Quantitative Assessment of the Cardiac Chambers and Its Clinical Significance. Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL.
http://archive.rsna.org/2014/14000904.html
