Here’s a quick fact about kidney health:
The amount of blood flowing through your kidneys is enormous compared to their size. Renal blood flow is about one liter per minute. This constitutes about 20% of your cardiac output through tissue that makes up only 0.5% of your body mass. The volume of each kidney is about 150 mL, which means that every minute, each kidney is perfused with more than three times its volume.
This shows how important your kidneys are in ensuring that everything runs smoothly in your body.
Modalities for evaluation of kidney function and early detection of kidney-related diseases include, but are not limited to, Magnetic Resonance Imaging(MRI), computed tomography (CT) scan, X-ray, ultrasound, and angiography.
In this guide, you’ll learn about an MRI of the kidney, what it can tell you, and how to prepare for it.
You’ll also learn about the average cost of this type of MRI and why your routine healthcare tests should include a preventative MRI of your kidneys.
What Do Your Kidneys Do?
Your kidneys are a pair of fist-sized, powerful organs found below your rib cage, one on each side of your spine. They are mainly responsible for taking waste and extra water out of your blood, which ultimately ends up as urine.
Your kidneys’ filtration rate, called the glomerular filtration rate (GFR), shows how well your kidneys are working.
Here’s a bird’s eye view of how your kidneys and the rest of the renal system (anything that has to do with kidneys is called “renal” ) work:
- First, blood with waste enters the kidneys through the renal arteries, large blood vessels that carry blood from the heart to the kidneys. The right renal artery connects to the right kidney and the left renal artery connects to the left kidney.
- Next, the kidneys clean your blood through millions of tiny blood filters called nephrons.
- Filtered waste from the blood passes through your ureter and goes straight to your bladder for storage. Once your bladder is full, you will feel the urge to release this waste through urine. As a result, urine passes through your urethra.
- Finally, filtered blood exits the kidneys and flows back to the heart through the renal vein.
Another vital kidney function is maintaining homeostasis, or the healthy balance of fluids and minerals in your body. Without this balance, other organs and systems in your body may not work normally.
Moreover, your kidneys make hormones that help:
- Stabilize your blood pressure
- Keep your bones strong
- Produce red blood cells
It’s worth noting that warning signs associated with renal disease often appear when the condition is already in its advanced state. In fact, it’s entirely possible to live with just one kidney.
If you have impaired kidney function or have renal issues, you may not experience any symptoms during the early stages. As a result, kidney disease or other issues may not be detected right away.
For this reason, regular screening of your kidney health and function is vital if you want to be more proactive about your overall wellness. This is where an MRI of the kidney can be helpful.
What Is a “Kidney MRI”?
An MRI of the kidney is a safe and painless procedure that uses radio waves and magnets to obtain 3D images of your kidneys.
It can also provide a functional assessment of your kidneys, including information about their GFR, blood volume and perfusion, diffusion, and oxygenation.
Your healthcare team will use these images to detect possible issues with your kidney health.
MRI scans of your kidneys can help see conditions like kidney cancer, chronic kidney disease, renal vein thrombosis, and the presence of tumors, masses, stones, or infection.
There are two types of MRI scans for your kidneys: imaging with or without contrast agents. A contrast agent is a dye or liquid injected into your body to make soft tissues visible during the imaging process.
Contrast MRIs use a contrast dye such as gadolinium or iodine. This type of MRI isn’t recommended for individuals who are pregnant, have a documented history of allergic reaction to gadolinium-based contrast agents, or have pre-existing conditions that affect the kidneys.
What Can an MRI of the Kidney Show?
Aside from giving your healthcare team a detailed look at the current state of your kidney and renal function, an MRI of the kidney can also help assess or visualize the following:
- Obstruction of urine flow, which can lead to acute renal failure
- Size of your kidneys, including the thickness of the cortex area where blood is filtered
- The presence of cysts that may occur in polycystic kidney disease
- Presence of blood clots in the vein that drains blood from the kidneys, also known as renal vein thrombosis
- Renal hypertension, high blood pressure or narrowing of the renal arteries that carry blood to the kidney
- Glomerulonephritis or a condition in which the glomeruli (found in nephrons) of the kidney is inflamed
- Acute tubular necrosis or a condition when the renal tubules are damaged, resulting in acute kidney injury
- Scarring of renal parenchyma (the cortex and medulla) or functional tissues of the kidneys
- Renal artery stenosis or a condition where there is a narrowing of the renal artery
- Renal cell carcinoma, the most common type of kidney cancer in adults
- Renal infections
- Renal stones
- Renal masses or lesions
Additionally, MRI has shown promise in the functional assessment of kidney transplants.
When Can Your Healthcare Provider Order an MRI of the Kidney?
Your healthcare provider may order an MRI of the kidney if they suspect that you may have abnormal or impaired kidney function. They may also ask you to undergo other kidney imaging techniques like ultrasound, angiography (a type of X-ray that looks at your blood vessels), and a CT scan to assess blood flow in your kidneys.
In his clinical practice, Dr. Joseph Vassalotti, chief medical officer at the National Kidney Foundation, recommends watching for these 10 possible signs that you may have kidney problems:
- Feeling more tired than usual and having trouble concentrating
- Trouble sleeping
- Dry, itchy skin
- Feeling the need to urinate more often
- Foamy urine
- Blood in the urine
- Persistent puffiness in the eyes
- Swollen feet and ankles
- Poor appetite
- Cramping muscles
Visualizing Kidney Health: MRI vs. CT Scan
Both MRI scans and CT scans can provide detailed imaging of the kidneys. They are both non-invasive, painless, and proactive ways to help detect signs of potential damage or disease.
The main difference lies in how each scan obtains the images of the inside of your body. MRI combines radio waves and a magnetic field, while a CT scan uses ionizing radiation in the form of X-rays.
It is worth noting that an MRI may be better at providing images of soft-tissue contrast and flow of bodily fluids such as kidney perfusion. On the other hand, a CT scan is often preferred for the identification of specific types of cancers.
Both MRI scans and CT scans can be used to identify the best biopsy site for cancer diagnosis.
Risks Associated With an MRI of the Kidney
While an MRI of the kidney is a safe procedure, it may carry some risks.
You’ll often hear that the radio-frequency energy used during an MRI scan could result in the body heating up, especially during long MRI scans. However, modern MRI machines have the capability to shut down as soon as they detect overheating.
In MRI scans, a contrast dye such as the gadolinium-based agent is introduced into the body through an intravenous (IV) injection. While these dyes are usually very safe, they may cause a problem for individuals with compromised or impaired kidney function. For example, nephrogenic systemic fibrosis (NSF) is an extremely rare but serious complication.
NSF is often characterized by thickening and tightening of the skin, common in patients with renal disease. Patients may also experience muscle weakness and bone pain. Symptoms can begin days, months, or even years after injection of the contrast material.
In summary, an MRI of the kidney is non-invasive and typically safe for most patients. MRI scans have been around since the 1980s, and safety standards are set in place to reduce risk as much as possible.
How Much Does an MRI of the Kidney Cost?
Abdominal MRI, which includes the kidneys, has an average cost of $1,600 to $7,600 in the U.S.
You’re likely to pay out of pocket if you’re planning an elective MRI for preventative screening.
How to Prepare For an MRI of the Kidney and How Long Does It Take?
Ask your healthcare provider for specific instructions before your MRI.
To prepare for your MRI:
- Remove all metallic objects like jewelry before your procedure. Let your healthcare team know about metallic implants or pacemakers. The same goes for tattoos or cosmetics which may contain metallic substances.
- Limit fluid intake at least 1 to 2 hours before your MRI. This will help avoid frequent restroom breaks in the middle of the procedure.
Take a Preventative Approach to Your Kidney Health
An ezra MRI is ideal for patients who want to be proactive about their kidney health. Think of the screening as an additional part of your routine health screenings, such as mammograms, Pap smears, and regular blood screenings. Regular kidney screenings present an insight into the overall health of your kidneys and may provide you with early warning signs of potential problems.
However, if you’re currently experiencing symptoms or undergoing treatment for an existing condition, a preventative MRI may not be for you, and you ought to consult with your healthcare provider.
If you’re ultimately interested in learning more about your kidney health with ezra, consider booking a scan or gifting a scan to a loved one. To ask questions and find out whether ezra might be the right fit for you, schedule a call with one of our team members.