If you have an excessive buildup of fat in your liver, you may be diagnosed with fatty liver disease. The most common form is non-alcoholic fatty liver disease (NAFLD), which often has no symptoms in its early stages. While it typically doesn’t cause immediate health issues, untreated NAFLD can progress to serious conditions such as cirrhosis or heart disease.
Magnetic Resonance Imaging (MRI) is one of the most effective methods for detecting NAFLD. It produces high-resolution images of your liver, allowing doctors to accurately assess fat content and make an informed diagnosis. If you’re concerned about the condition, here’s what you need to know about a fatty liver MRI - including how to arrange a scan.
What is Fatty Liver (Hepatic Steatosis)?
Fatty liver, or hepatic steatosis, occurs when excess fat builds up in the liver - specifically, when more than 5-6% of the liver’s weight consists of fat. In medical terms, this means liver cells (hepatocytes) accumulate an unusually high amount of triglycerides (a type of fat). When this happens, a person may be diagnosed with fatty liver disease.
There are two main types of fatty liver disease:
-
Alcoholic fatty liver disease (AFLD) - fat buildup caused by drinking too much alcohol
-
Non-alcoholic fatty liver disease (NAFLD) - fat accumulation unrelated to alcohol use, often associated with obesity, high cholesterol, insulin resistance, or type 2 diabetes
NAFLD is the more common form and is currently the leading cause of chronic liver disease worldwide, affecting an estimated 32% of the global adult population. While NAFLD may not be serious in its early stages, it can progress to non-alcoholic steatohepatitis (NASH) - a more severe form that involves liver inflammation, cell damage, and fibrosis (scarring).
If left untreated, NASH can lead to advanced liver damage, including cirrhosis (permanent scarring), liver failure, and even liver cancer.
Symptoms
Both AFLD and NAFLD are often called ‘silent diseases’ because they often cause no symptoms in the early stages. Most people only discover they have fatty liver during routine blood tests or imaging done for other reasons.
However, some people may experience mild, non-specific symptoms such as:
-
Fatigue or low energy
-
Mild discomfort or a dull ache in the upper right side of the abdomen
If fatty liver progresses to steatohepatitis, symptoms may become more noticeable and can include:
-
Unintentional weight loss
-
Loss of appetite
-
Nausea
-
Persistent fatigue or weakness
In serious cases where cirrhosis has developed, symptoms often include:
-
Yellowing of the skin and eyes (jaundice)
-
Swelling in the legs (edema) or abdomen (ascites)
-
Feelings of confusion or loss of concentration, sometimes called ‘brain fog’ or hepatic encephalopathy
Can an MRI Detect a Fatty Liver?
If a blood test or ultrasound has suggested the presence of a fatty - or steatotic - liver, your GP may recommend an MRI scan. MRI produces high-resolution 3D images of the body’s internal organs and soft tissues. Specialised MRI protocols can focus on specific areas, such as the liver, to provide detailed images of liver tissue and detect fat accumulation.
In fact, MRI is widely considered the most accurate non-invasive method for the quantification of liver fat.
One advanced technique used in liver MRI is proton density fat fraction (PDFF), which measures the percentage of fat within the liver. Research has shown that MRI-PDFF has high diagnostic accuracy, with:
-
77-95% sensitivity (ability to correctly identify those with liver fat)
-
81-97% specificity (ability to correctly identify those without liver fat)
This makes MRI more precise than other imaging techniques, such as computed tomography (CT), particularly in detecting mild steatosis.
However, MRI is less effective at distinguishing between NAFLD and more severe conditions such as NASH. In such cases, a liver biopsy is typically required to confirm the diagnosis and assess liver inflammation or fibrosis.
How an MRI Scan Detects a Fatty Liver
MRI differs from other imaging techniques by using radio waves and powerful magnets to generate detailed images of the body’s internal structures. The machine’s strong magnetic field aligns protons in the body’s hydrogen atoms. When radiofrequency pulses are applied, they temporarily disturb this alignment. As the protons return to their original state, they emit signals that the scanner detects to create detailed images.
A liver MRI works by distinguishing between fat and water content in the liver tissue to quantify the amount of fat present. Protons in water and fat molecules have slightly different magnetic resonance frequencies, with fat protons having a lower signal intensity (brightness) than water protons. PDFF measures the proportion of fat by calculating the ratio of the fat signal to the combined signal from both fat and water.
For instance, a PDFF value of 0.10 indicates 10% fatty infiltration (10% of the liver tissue contains fat). Higher than for a normal liver and consistent with hepatic steatosis.
Diagnosing Hepatic Steatosis
Clinical History and Risk Assessment
The first step in liver steatosis diagnosis is a thorough review of your medical history. Your doctor will ask about:
-
Current and past medical conditions
-
Family history of liver disease
-
Alcohol consumption
-
Medications you’re taking
You may also be asked about symptoms such as fatigue or discomfort in the upper right part of your abdomen. Although NAFLD is often asymptomatic, some patients do report mild, non-specific symptoms.
Physical Examination
Usually conducted alongside the history review, a physical exam may include:
-
An abdominal check for signs of tenderness or an enlarged liver
-
Assessment for signs of jaundice or liver inflammation
-
Measurement of body mass index (BMI) to evaluate for obesity, a major risk factor for fatty liver
Liver Function Blood Tests (e.g. ALT, AST)
Liver blood tests look at liver enzymes (chemicals), proteins, and other substances produced by the liver to check for signs of abnormality and evaluate liver health. Common test categories include:
-
Liver enzyme tests - looking for elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), or gamma-glutamyl transferase (GGT)
-
Liver function tests (LFT) - looking at albumin and bilirubin levels, which can be abnormal in more advanced disease stages
-
Tests to rule out other diseases - such as hepatitis, Wilson’s disease, or iron overload (hemochromatosis)
-
Metabolic tests - assessing for lipids associated with fatty liver, such as cholesterol and triglycerides
Blood tests may be done during your initial appointment, or scheduled separately depending on availability.
Ultrasound of the Liver
An ultrasound is typically the first imaging test used to evaluate fatty liver. It’s a non-invasive procedure that uses sound waves to create images of the liver and nearby organs (e.g. pancreas, spleen, gallbladder).
In fatty liver disease, the liver often appears brighter (increased echogenicity) due to fat accumulation in the liver parenchyma (functional tissue). While useful for detecting moderate to severe steatosis, ultrasound is less sensitive for mild cases and cannot assess fibrosis or inflammation - so additional tests may be needed.
MRI or CT Scan
Follow-up imaging after a liver ultrasound typically involves either a CT or MRI scan. CT scans are generally faster and more affordable, but they expose the patient to mild radiation and are less accurate than MRI in evaluating liver fat.
CT uses multiple X-ray images combined by a computer to create detailed cross-sectional images. On a non-contrast CT, a fatty (steatotic) liver appears darker due to the lower density of fat compared to normal liver tissue. This results in reduced hepatic attenuation, which is the measure of how much the liver tissue absorbs the X-ray beam. Normal liver attenuation typically ranges between 50-75 Hounsfield units (HU). Values below this range may suggest fatty liver. However, liver attenuation can be affected by other factors - such as the presence of iron in the liver - which can obscure accurate interpretation.
Like ultrasound, CT is relatively insensitive to mild steatosis, with reported sensitivities ranging from 52-62%. Contrast-enhanced CT scans, which use iodine-based dyes to improve image quality, are also limited for detecting fatty liver because the contrast agent can artificially increase attenuation values.
Due to these limitations, MRI is generally preferred when available, as it offers greater sensitivity and precision in quantifying liver fat.
FibroScan (Transient Elastography)
A FibroScan is a special type of ultrasound that measures liver stiffness and fat content. It’s helpful for identifying more advanced stages such as NASH.
The scan is painless and works similarly to regular ultrasound - you’ll lie on your side while a technician uses a probe on your upper right abdomen. The device sends sound waves into your liver and measures how quickly they pass through, which helps assess the degree of stiffness.
Exclusion of Other Liver Diseases
After your blood tests and imaging, your doctor will assess whether your liver changes are due to fatty liver or another underlying condition. Other liver diseases that need to be ruled out include:
-
Viral hepatitis (Hepatitis B or C)
-
Autoimmune liver diseases, such as primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC)
-
Hemochromatosis (iron overload)
-
Wilson’s disease (copper accumulation)
Liver Biopsy (if needed)
You may need a biopsy if there’s uncertainty in the diagnosis or concern that fatty liver may have progressed to NASH or cirrhosis. This involves inserting a thin needle through the abdomen to take a small tissue sample, which is examined under a microscope to assess fat content, inflammation, and scarring.
Although slightly more invasive, a biopsy provides detailed information about disease stage and progression.
Review of Medications and Alcohol Intake
As part of the diagnostic process, your doctor will carefully review your alcohol intake and current medications. Alcohol consumption helps differentiate between AFLD and NAFLD. If alcohol use is within safe limits (typically under 30g/day for men and 20g/day for women), a diagnosis of NAFLD is more likely.
Some medications can contribute to or worsen hepatic steatosis, including:
-
Corticosteroids (e.g. for asthma or arthritis)
-
Methotrexate (used for autoimmune conditions)
-
Tamoxifen (for breast cancer)
-
Antiretrovirals (for HIV)
-
Certain chemotherapy agents
Discussing your full medication list with your provider helps rule out drug-induced causes of fatty liver.
Monitoring and Follow Up
If you have been diagnosed with hepatic steatosis, regular follow-up is important to monitor for disease progression. This may include:
-
Routine liver imaging every 1-2 years
-
Periodic blood tests to check liver function and associated metabolic risk factors
-
Lifestyle guidance - including dietary adjustments, weight management, and limiting alcohol intake
You should also report any new or worsening symptoms, such as fatigue, abdominal discomfort, or jaundice.
Causes of Fatty Livers
Hepatic steatosis can result from a variety of factors, including lifestyle choices, metabolic conditions, and certain medical treatments. Key contributors include:
-
Obesity
-
Drinking too much alcohol
-
Type 2 diabetes or insulin resistance
-
Effects of certain prescribed medications (detailed above)
-
Metabolic disorders
-
Viral conditions, such as viral hepatitis
-
High blood pressure
-
High cholesterol
-
Smoking
-
Age (fatty liver is more prevalent in over-50s)
Prognosis and Treatment
The good news is that fatty liver disease is often reversible in its early stages, particularly before it develops into fibrosis or cirrhosis. Early intervention with lifestyle changes can significantly improve liver health. Recommended steps include:
-
Eating a healthy diet low in saturated fats and added sugars
-
Engaging in regular physical activity
-
Reducing on alcohol intake
-
Quitting smoking
-
Taking medications to manage conditions such as diabetes, high blood pressure, or high cholesterol
If a fatty liver disease progresses to fibrosis (the early stages of scarring), ongoing medical treatment and lifestyle changes are essential. In some cases, liver fibrosis can be partially reversed with sustained treatment and a healthy lifestyle.
If the disease advances to cirrhosis, the scarring becomes permanent. Although the damage cannot be undone, treatment and lifestyle adjustments can halt further deterioration. This may help prevent serious complications such as liver failure or liver cancer.
Why an MRI Scan is a Good Option
MRI is widely regarded as one of the best imaging methods for evaluating the liver, especially when fatty liver disease is suspected. Among MR imaging techniques, PDFF-MRI is considered the gold standard for accurately detecting both mild and severe hepatic steatosis. It provides precise, quantitative data and is highly respected within the radiology community.
In addition to its accuracy, MRI is a safe, non-invasive option that involves no radiation exposure, unlike CT scans. It also requires minimal preparation, making it particularly well-suited for assessing NAFLD.
However, in more advanced cases - such as when fatty liver progresses to NASH or cirrhosis - a liver biopsy may still be necessary to confirm the diagnosis and assess the extent of liver damage.
Find an MRI Scan for a Fatty Liver
If you’re concerned about fatty liver disease and are considering a private liver scan, we offer a simple and efficient booking process. You’ll receive guidance from a qualified clinician and follow-up support to help you understand your results. Just complete our quick online form and select a convenient scanning location near you.
If you’re unsure whether an MRI scan is the right choice, you can also schedule a 15-minute consultation with a clinician before booking.
