MRA vs MRI: What Is The Difference?
MRI (magnetic resonance imaging) and MRA (magnetic resonance angiography) are two powerful imaging techniques that utilize strong magnetic fields and radio waves to create comprehensive pictures of the inside of your body. Though both acronyms share the initial “MR,” they offer distinct functionalities. Therefore, understanding these differences can help you approach your upcoming scan with clarity and confidence. So, let’s understand the difference between MRA vs MRI and what they offer.
What is an MRI?
Let’s start with understanding “what is an MRI?”. An MRI scan provides a highly detailed view of various organs, tissues, and bones within your body. Doctors may identify a variety of medical issues with this painless, non-invasive process that creates complex cross-sectional pictures. Some common uses of MRI include:
Examining the brain: Identifying tumors, strokes, multiple sclerosis, and abnormalities in the brain structure.
Evaluating the spine: Detecting herniated discs, spinal cord injuries, and tumors in the spine.
Assessing muscles and joints: Diagnosing ligament tears, muscle strains, and sports injuries.
Investigating the abdomen and pelvis: Identifying tumors, liver disease, and abnormalities in the female reproductive organs.
How Does an MRI Work?
An MRI machine consists of a large cylindrical magnet that generates a strong magnetic field. When you lie inside the scanner, the magnetic field aligns the protons (tiny particles within your body’s atoms).
Radio waves are then pulsed at specific frequencies, causing these protons to absorb energy and change their alignment. As the protons realign back to their original state, they release energy that the MRI machine then detects. The complex signal received is then processed by a computer to create detailed images of your internal structures.
How to Prepare for an MRI
An MRI scan is a safe and painless procedure, but some preparation is necessary to ensure a smooth experience and generate optimal images. Here is a thorough explanation of what to anticipate before your scan and how to be ready for an MRI:
Metal Screening
Safety is paramount. You will undergo a thorough screening process to identify any metal objects on or within your body. This includes:
Filling out a questionnaire: This form will inquire about any implanted medical devices (pacemakers, artificial joints), surgical clips, piercings, or tattoos with metallic ink.
Metal detector scan: A handheld metal detector helps check for external metal objects such as jewelry, watches, belts, or keys.
Fasting Instructions
Depending on the specific area under examination, your doctor may advise you to fast for a few hours before the scan. This is typically the case for abdominal or pelvic MRIs, as food or digestive processes can obscure the images. However, for MRIs of other body parts, you might be able to eat a light meal beforehand.
Clothing Change
For the scan, you will likely have to change into a hospital gown. This is because most clothing contains metal fasteners (zippers, buttons) that are incompatible with the MRI machine’s magnetic field. The facility will provide a secure locker for your belongings.
Medication Review
Tell your doctor about all the medications you take, including over-the-counter, prescription, and herbal supplements. Certain medications may interact with the contrast dye used in some MRIs or may not be safe in the strong magnetic field. Your doctor will discuss any changes to your medication schedule that may be necessary prior to the scan with you.
Claustrophobia Management
If you experience claustrophobia (fear of enclosed spaces), let your doctor know in advance. For more guidance please read: Tips To Minimize Claustrophobia Techniques like relaxation exercises or anti-anxiety medication can be helpful in managing anxiety during the scan. Some MRI facilities offer open scanners that may be more comfortable for claustrophobic patients.
Knowing What to Expect
The MRI technologist will walk you through the process step-by-step and address any questions you may have. The scan itself typically takes 30 to 60 minutes, and you will be positioned inside the scanner while lying on a movable table.
The machine may produce loud knocking noises during operation, but earplugs or headphones will be provided to minimize discomfort. You may also be given a call button to communicate with the technologist if needed.
What is an MRA?
Now, let’s move to “What is an MRA?” An MRA (magnetic resonance angiography) is a form of MRI that is especially useful for examining blood arteries throughout the body. It utilizes the same basic principles of magnetic fields and radio waves as an MRI but with a specific focus on vascular structures. MRAs are particularly helpful in:
Detecting blockages or narrowing of arteries: This can be crucial in diagnosing and managing cardiovascular diseases like peripheral artery disease and carotid artery stenosis.
Identifying aneurysms: These are weak bulges in the wall of a blood vessel that can rupture and cause life-threatening bleeding.
Evaluating blood flow to the brain: MRAs can help diagnose conditions like stroke and assess the risk of future strokes.
How Does an MRA Work?
Similar to an MRI, an MRA scan uses a magnetic field and radio waves to create images. However, during an MRA, a contrast agent (a special dye) may be injected into your bloodstream to enhance the blood vessel visualization on the final images. This contrast agent makes the blood vessels appear brighter against surrounding tissues, allowing for a clearer evaluation of blood flow and any potential abnormalities.
How to Prepare for an MRA
Similar to an MRI, preparing for an MRA involves ensuring safety and optimal image quality. Here’s a breakdown of how to prepare for an MRA:
Contrast Dye Allergy
Since MRAs often utilize a contrast agent to enhance blood vessel visualization, it’s crucial to inform your doctor about any allergies you have, particularly to contrast dyes used in medical imaging. Knowing about potential allergies beforehand allows the doctor to choose a safe alternative contrast agent or adjust the procedure accordingly.
Kidney Function Test
In certain instances, prior to giving you the contrast agent, your doctor could request a blood test to evaluate your kidney function. This is because your kidneys are responsible for removing contrast dye from your blood. The test results will help determine if your kidneys are healthy enough to eliminate the contrast material after the scan effectively.
Fasting Instructions
Depending on the type of MRA being performed, you may have to fast for a few hours beforehand. For instance, an MRA of the abdomen or pelvis might require fasting to avoid food or digestive processes obscuring the blood vessels in those areas. However, for MRAs of other body parts, you might be able to eat a light meal. Your doctor will provide specific instructions based on the scan type.
Medication Review
Just like with an MRI, discuss all medications you are taking with your doctor beforehand. Certain medications may interact with the contrast agent or be unsafe in the strong magnetic field. Your doctor will advise on any necessary adjustments to your medication regimen before the scan.
Claustrophobia Management
If you experience claustrophobia, let your doctor know in advance. Similar to an MRI, relaxation techniques or anti-anxiety medication can be helpful in managing anxiety during the MRA scan. Some facilities may offer open scanners for a more comfortable experience.
Bottom Line
To summarize, MRA and MRI are both useful diagnostic procedures that use magnetic fields and radio waves to provide comprehensive images of the body’s internal structures. While an MRI offers a comprehensive view of organs, tissues, and bones, an MRA focuses specifically on visualizing blood vessels. Therefore, understanding the distinct functionalities of these techniques can empower you to approach your upcoming scan with a clear understanding of its purpose and preparation requirements. If you have any concerns about MRA vs MRI or an upcoming scan, always consult with your doctor and choose an open MRI in Edison.