A magnetic resonance imaging (MRI) scan of the knee provides highly detailed images of the joint’s internal structures. This non-invasive diagnostic tool uses a powerful magnetic field and radio waves to visualize soft tissues, including ligaments, cartilage, tendons, and bone marrow. A knee MRI is typically ordered to investigate injuries like ligament tears, meniscal damage, or degenerative conditions, giving physicians a comprehensive view for accurate diagnosis. Understanding the duration of the scan is helpful for patients preparing for the procedure.
How Long the Knee MRI Scan Actually Takes
The time a patient spends actively being scanned inside the MRI machine for a knee examination usually falls within a range of approximately 25 to 45 minutes. This duration represents the time the machine is capturing images, not the entire appointment.
The scan itself is not a single photograph but a collection of multiple sequences, each lasting from a few seconds to several minutes. During this period, the patient lies still on a table positioned within the scanner’s bore. Remaining completely motionless is necessary throughout each sequence to prevent blurring or motion artifacts, which can compromise the diagnostic quality of the images.
Factors That Increase or Decrease Scan Duration
The length of the active scan time can fluctuate based on specific clinical and technical requirements.
A primary factor that extends the procedure is the need for a contrast agent, such as Gadolinium, administered through an intravenous line. If contrast is required to highlight blood vessels, inflammation, or certain tumors, the technologist must pause the imaging, inject the dye, and then run additional specialized sequences. This typically adds 10 to 15 minutes to the total scan time.
Patient movement is a significant technical variable that can increase the duration. Any shifting or wiggling during a sequence will result in a poor-quality image, forcing the technologist to repeat that entire sequence. The complexity of the physician’s imaging request dictates the necessary protocol, as a request for highly specialized or numerous imaging views will naturally require the acquisition of more sequences.
Total Appointment Time Commitment
The total amount of time a patient should plan to spend at the imaging facility is considerably longer than the scan itself, typically ranging from 60 to 90 minutes. This difference accounts for the necessary preparatory and post-scan procedures.
Before entering the scan room, a patient must complete administrative tasks like check-in, paperwork, and insurance verification. A crucial pre-scan step involves a thorough safety screening for all metal objects and implants, followed by changing into a gown or scrubs.
This preparation and consultation with the technologist to review medical history and answer questions can take between 15 and 30 minutes. After the scan is complete, the patient needs time to dress and wait briefly while the technologist confirms that all images are technically adequate before being released.