Cine MRI
The introduction of steady-state free precession (SSFP) pulse sequences has revolutionized cine MRI of the heart. These techniques have inherent high signal and produce high contrast images of the blood pool and myocardium, without the injection of contrast.
Furthermore, because repetition times are so short (approximately three milliseconds), a cine loop of the heart can be acquired in a comfortable breath-hold of less than 10 seconds. A number of acceleration techniques, called parallel imaging, have recently become available and now allow images to be acquired in four to five seconds. With this, the entire heart can be evaluated in a handful of breath holds, making the exam much more tolerable for the patient.
At our institution, we use the TrueFISP (true fast imaging with steady-state precession) technique for cine imaging of the heart. ECG-gating is used in order to freeze cardiac motion and prevent artifacts. Parallel imaging is utilized to speed up the acquisition and it is now possible to complete the entire functional portion of the exam in about five to six breath holds, of less then 10 seconds each. For patients with abnormal cardiac rhythms, where ECG-gating is suboptimal, there are methods now available to reject ectopic beats and prevent motion artifact. For patients that cannot hold their breath, there are alternative real-time cine techniques available that do utilize gating. In summary, with the different strategies available now for cine imaging, it is always possible to complete a diagnostic study, even in very sick patients.
Cine imaging is carried out in conventional short axis and long axis orientations. Chamber size, wall motion and myocardial wall thickness are assessed from these images. In addition, using standard post-processing software, routine cardiac parameters (i.e. ejection fraction, end systolic volume, end diastolic volume, myocardial mass, cardiac output) are measured and calculated and these values are included in the report. These parameters are particularly useful for follow up of disease progression.
Functional cardiac MR can also be used to assess valvular stenosis and regurgitation, anatomic abnormalities, and septal defects with shunts. 
Key Points
- Cine MRI of the heart is carried out using TrueFISP. ECG-gating is used to prevent cardiac motion artifacts.
- Parallel imaging is used to speed up the acquisition so that the entire heart can be assessed in a handful of breath holds of less than 10 seconds each.
- There are a number of alternative techniques now available for patients with arrhythmia or who cannot hold their breath. In short, it is always possible to complete a diagnostic study, even in very sick patients.
- Conventional short axis and long views are obtained, similar to echocardiography. Chamber size, wall motion and myocardial wall thickness are assessed from these images.
- Cardiac parameters, such as ejection fraction, are routinely calculated and included in the report.