Cine Magnetic Resonance Imaging (MRI) is a specialized application of standard MRI technology designed to capture movement and dynamic processes within the body. The term “cine,” borrowed from “cinema,” describes the method’s ability to produce a short, looping video clip instead of a single static image. This dynamic imaging provides a functional view of organs and fluid flow, offering insights into how a system is working, not just what it looks like structurally. While conventional MRI shows anatomy, Cine MRI reveals physiology, which is necessary for diagnosing conditions involving motion or fluid dynamics.
The Mechanism of Dynamic Imaging Acquisition
Creating a moving image requires a technical shift from standard MRI, which typically takes several minutes to capture a single static image. The fundamental challenge of Cine MRI is the need for extremely rapid data acquisition to capture the different phases of a biological cycle, such as a single heartbeat. To achieve this, the scanner utilizes very fast imaging sequences, such as balanced steady-state free precession (SSFP). SSFP is commonly used because it produces high contrast between fluid, like blood, and surrounding soft tissue, making moving elements appear bright against a darker background.
The process relies heavily on a technique called “gating,” which synchronizes the MRI scan to a specific, repeating biological cycle within the patient. For cardiac imaging, electrocardiogram (ECG) leads are placed on the patient’s chest to monitor the heart’s electrical activity, providing a reference point for each heartbeat. The scanner collects small segments of imaging data—called k-space data—at multiple, precisely timed intervals throughout the cardiac cycle, often across several heartbeats.
This segmented data collection process is necessary because the MRI machine cannot acquire a full image fast enough during a single beat. Instead, rapid, partial data from corresponding phases of multiple heartbeats are collated and assigned to a specific frame, or “cine phase,” of the final image. Once enough data has been collected to fill all the frames across the entire cycle, a computer reconstructs these individual phases into a sequential series of images. When played back quickly, this sequence creates a smooth, continuous video loop that illustrates the organ’s movement.
Primary Clinical Applications of Cine MRI
The ability to visualize function makes Cine MRI a powerful diagnostic tool, particularly in systems defined by constant motion. It is considered a reference standard for evaluating the mechanical function of the heart.
A specific and quantifiable metric derived from cardiac Cine MRI is the ejection fraction, which measures the percentage of blood pumped out of a ventricle with each beat and is a key indicator of heart health. The technique also provides detailed visualization of blood flow through the heart’s valves, allowing physicians to assess the severity of conditions like mitral or aortic regurgitation, where blood leaks backward. This high contrast enables assessment of intracardiac flow patterns, helping to diagnose congenital heart defects.
Cine MRI is also uniquely suited for studying the movement of cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. This application, often using Cine phase-contrast MRI, is important for diagnosing conditions where CSF flow is obstructed. The dynamic images can reveal if the fluid is properly circulating or if it is being blocked at certain points, such as the foramen magnum at the base of the skull.
Conditions like Chiari malformation, where brain tissue extends into the spinal canal, are often evaluated using this technique to determine if the malformation is impeding CSF movement, which can lead to fluid accumulation or syringomyelia. Beyond the heart and central nervous system, Cine MRI can also assess the dynamics of joint movement or visualize the movement of the bowel during conditions like MR enterography.
Preparing for and Undergoing a Cine MRI Scan
Preparation for a Cine MRI begins with the standard safety precautions required for any magnetic resonance imaging procedure. Patients must remove all metallic items, including jewelry, glasses, and certain hearing aids. They must also inform the technologist of any internal metal, such as pacemakers or surgical clips, which may interfere with the strong magnetic field. The examination involves lying on a table that slides into a tube-shaped scanner, and patients are provided with earplugs or headphones to mitigate the loud operational noise.
The procedure often takes longer than a standard MRI, sometimes ranging from 30 to 60 minutes for a cardiac study, due to the need for repeated sequences to gather all the data segments. For dynamic studies, small electrode patches are placed on the chest to monitor the heart rate and enable the necessary synchronization.
Patient cooperation is important for obtaining high-quality images, especially during sequences that involve the chest or abdomen. The technologist will ask the patient to hold their breath for brief periods, typically less than 20 seconds, to minimize motion artifacts caused by respiration. Although the technologist is in an adjacent room, they maintain two-way communication throughout the scan to provide instructions and ensure the patient remains comfortable and still.