The field of view (FOV) in MRI defines the size of the area being imaged. It represents the dimensions of the precise anatomical region included in the MRI scan.
In more detail:
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Definition: The FOV dictates the portion of the patient's body that is captured in the MRI image. Think of it like the zoom setting on a camera; a smaller FOV focuses on a smaller area with greater detail, while a larger FOV encompasses a broader region but might sacrifice some fine detail.
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Dimensions: The FOV can be square (equal dimensions in both directions) or rectangular/asymmetric (different dimensions).
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Units: It is typically measured in millimeters (mm) or centimeters (cm).
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Impact on Image Quality: The FOV significantly impacts image resolution and scan time.
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Smaller FOV: Results in higher spatial resolution because the same number of pixels are used to represent a smaller area. This allows for finer details to be visualized. However, it also increases the risk of "wrap-around artifact," where anatomy outside the FOV is projected onto the image.
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Larger FOV: Includes more anatomy but at the expense of resolution. It reduces the risk of wrap-around artifact but can make it harder to visualize small structures.
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Clinical Considerations: The selection of an appropriate FOV is crucial for accurate diagnosis. It must be large enough to include the area of interest but small enough to provide adequate resolution.
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Example: If a doctor orders an MRI of the knee with an FOV of 20 cm x 20 cm, the resulting image will display a 20 cm by 20 cm area of the knee.
