Common Words in Ultrasound, CT and MRI Reports: What Do They Mean?

The medical terms used in ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) reports can sometimes be worrying for patients.

Seeing a word such as “lesion”, “mass”, “hypodense area”, “signal change”, “dilatation” or “lymph node” in a report does not on its own mean that cancer or a serious condition is present.

An imaging report is a whole. Rather than taking one word out of the report and interpreting it, the finding’s location, size, shape, internal structure and enhancement characteristics, its change since previous images, and the patient’s clinical situation all have to be weighed together.

Do ultrasound, CT and MRI show the same thing?

No. These methods work on different principles and are strong in different areas.

Ultrasound

Builds an image from sound waves. It is often used to assess:

• The liver
• The gallbladder
• The bile ducts
• The kidneys
• The spleen
• Fluid in the abdomen

It involves no radiation.

Computed tomography — CT

Uses X-rays to build cross-sectional images of the body. It is useful particularly for assessing emergency abdominal conditions, inflammation, masses, blood vessels and many conditions of the organs. CT uses ionising radiation.

Magnetic resonance imaging — MRI

Builds an image using a strong magnetic field and radio waves. It uses no ionising radiation. It can offer important advantages in the detailed assessment of the liver, pancreas, bile ducts and soft tissues.

MRCP is an MRI-based method used particularly for assessing the bile and pancreatic ducts.

What does “lesion” mean?

This is one of the words that worries patients most.

Lesion = an abnormal or different appearance noticed in a tissue by an imaging method.

But the word “lesion” does not mean “cancer”. A lesion can arise from many different causes:

• A simple cyst
• A haemangioma
• An area of fat
• A benign tumour
• An inflammatory change
• An infection
• Another structural change
• A malignant tumour

So “a lesion was found” is not on its own a diagnosis.

What does “cystic lesion” mean?

A cystic lesion describes a structure containing mainly fluid. Simple cysts in the liver, for example, are quite common and are mostly harmless.

But not all cystic lesions are the same. The wall, the contents, any septations, whether there are nodules, and enhancement characteristics all matter.

The word “cystic” does not on its own mean benign or malignant.

What does “solid lesion” mean?

Solid means the lesion has the structure of tissue rather than being a simple fluid-filled cyst.

Solid does not mean cancer. Haemangiomas, focal nodular hyperplasia (FNH), adenomas and many other harmless structures can be solid too.

Imaging characteristics matter in determining what a solid lesion is.

What does “hyperechoic” mean?

This word appears particularly in ultrasound reports.

Hyperechoic means the area examined reflects more ultrasound waves than the surrounding tissue and appears brighter on the image. For example, the following can look hyperechoic:

• Fatty liver
• Some haemangiomas
• Some other lesions

Hyperechoic does not mean cancer.

What does “hypoechoic” mean?

A hypoechoic area reflects fewer ultrasound waves than the tissue around it and looks darker on the image.

Many different benign or malignant structures can be hypoechoic. So a diagnosis cannot be made from the word “hypoechoic” alone.

What does “hypodense” mean?

This term is used particularly in CT reports. A hypodense area is one that appears at a lower density on CT than the tissue around it.

A simple cyst containing fluid, for instance, can appear hypodense. But other lesions can be hypodense too. Hypodense does not mean malignant.

What does “hyperdense” mean?

Hyperdense means an area that appears denser or brighter on CT than the structures around it. Blood, calcification or some lesions can appear hyperdense.

Again, this word is not on its own the name of a disease.

What do “hyperintense” and “hypointense” mean?

These words appear particularly in MRI reports.

• Hyperintense — an area giving a brighter signal than the surrounding tissue on a particular MRI sequence.
• Hypointense — an area giving a darker signal than the surrounding tissue.

But there is an important detail here: the appearance on MRI changes with the sequence used. A lesion can be hypointense on T1 and hyperintense on T2.

So it is not possible to understand what a lesion is by reading the word “hyperintense” alone.

What do “contrast uptake” or “enhancement” mean?

In some CT and MRI examinations a contrast agent is given into a vein. The change in the appearance of a tissue or a lesion after the contrast agent is called enhancement.

The following can give important information in determining a diagnosis:

• Whether the lesion takes up contrast
• In which phase it enhances
• How the enhancement is distributed
• How it changes in the later phases

Taking up contrast does not on its own mean cancer. Many harmless lesions also enhance in characteristic ways.

What does “dilatation” mean?

Dilatation means widening. If a report says “dilatation of the intrahepatic bile ducts”, for instance, it states that the bile ducts within the liver are wider than normal.

Causes can include:

• A stone in the bile duct
• Narrowing of the bile duct
• Other conditions obstructing the flow of bile

But the degree, location and cause of the dilatation have to be assessed separately.

What does “the common bile duct is dilated” mean?

The choledochus is the main bile duct. In assessing its diameter, the following matter:

• Age
• Whether the gallbladder is present
• Previous operations
• The clinical situation
• Laboratory results

In people whose gallbladder has been removed in particular, the bile duct diameter can be wider.

So it cannot be said, from the millimetre value alone, that “the bile duct is blocked”.

What does “hepatomegaly” mean?

It means the liver is larger than normal. Hepatomegaly can have many different causes:

• Fatty liver
• Some types of hepatitis
• Heart disease
• Metabolic conditions
• Infiltrative conditions
• Other causes

Hepatomegaly is not on its own the name of a disease.

What does “splenomegaly” mean?

It means the spleen is larger than normal. It can have many causes, from infections to blood disorders and portal hypertension.

In chronic liver disease in particular, an enlarged spleen can be an important finding for portal hypertension. But splenomegaly does not on its own make a diagnosis of cirrhosis.

What does “ascites” mean?

Ascites is a collection of more fluid than normal in the abdominal cavity.

Cirrhosis is one of the important causes but not the only one. Heart disease, malignancies, infections and other conditions can also cause fluid to collect in the abdomen.

Ascites does not on its own mean cirrhosis.

What do “lymph node” or “lymphadenopathy” mean?

Lymph nodes are normal parts of the body’s immune system. Seeing lymph nodes on an imaging report does not always mean disease.

Lymph nodes can enlarge in:

• Infections
• Inflammation
• Some conditions of the immune system
• Some cancers

In assessing them, not only size matters but also location, shape, internal structure, number and change over time.

“A lymph node was seen” does not mean “the cancer has spread”.

What does “calcification” mean?

Calcification means a deposit of calcium in a tissue. It can be seen after old infections, past inflammation, in some harmless lesions and in many other situations.

The organ where the calcification is found and the way it looks both matter.

What does “incidental finding” mean?

Incidental means a finding discovered by chance during an examination done for another reason. Seeing a small cyst in the liver while looking for a kidney stone, for instance, is an incidental finding.

Incidental does not mean unimportant. But a large proportion of incidental findings can be harmless and may need only follow-up, or no action at all.

What does “millimetric” mean?

Millimetric describes a finding that is small, of the order of millimetres. This word does not say whether the finding is benign or malignant.

In the phrase “a millimetric hypodense lesion in the liver”, for instance, only a small area is being described. What the lesion means is assessed from its other imaging characteristics.

What does “could not be characterised” mean?

This phrase does not mean “it may be cancer”. It means the structure of the finding could not be determined definitively by the imaging method used.

A very small lesion, for instance, may not be adequately assessed by ultrasound or CT. In that case the radiologist may, if they think it necessary, recommend another investigation:

• A follow-up ultrasound
• CT with contrast
• MRI
• MRCP
• EUS

What does “follow-up is recommended” mean?

A radiologist may want to see how some findings change over time. So recommendations such as “review in 3 months”, “imaging in 6 months” or “annual follow-up” can appear in a report.

A recommendation to follow up does not mean there is cancer. But it is important not to forget the review that has been recommended.

What does “stable compared with the previous examination” mean?

Stable means the finding shows no marked change compared with the previous imaging. When it says “the lesion is stable compared with the previous examination”, it means no meaningful change in size or appearance has been found.

In most situations this is valuable information. This is why it matters to keep old ultrasound, CT and MRI images for comparison.

What does “progression” mean?

Progression means a finding is advancing or increasing. This can take the form of:

• An increase in size
• An increase in number
• An increase in the extent of the disease

But what the word progression means depends on which condition the report was made for.

What should you do if a lesion is found on your report?

1. Do not focus on a single word. “Lesion”, “hypodense” or “solid” is not on its own a diagnosis.
2. Read the conclusion section of the report. The radiologist’s overall assessment matters.
3. Look at the size of the lesion. But benign and malignant are not distinguished by size alone.
4. Find your old imaging. A finding unchanged for years is not the same as one that is new or growing.
5. Weigh your laboratory results together with it. In conditions of the liver, pancreas and bile ducts in particular, blood tests give important information.
6. Further investigation is done where needed. Not every lesion needs CT, MRI, PET-CT or a biopsy.

When should assessment not be delayed?

Remember

• LESION Does not mean cancer.
• CYSTIC Describes a structure containing mainly fluid.
• SOLID Describes a structure of tissue; it does not on its own mean malignant.
• HYPERECHOIC / HYPOECHOIC Describe the ultrasound appearance.
• HYPODENSE / HYPERDENSE Describe the appearance on CT.
• HYPERINTENSE / HYPOINTENSE Describe MRI signal characteristics.
• DILATATION Means a duct or structure has widened.
• LYMPH NODE Does not on its own mean cancer or metastasis.
• FOLLOW-UP RECOMMENDED Does not mean a diagnosis of cancer has been made; the review recommended should not be neglected.

The most important message

A single word in an imaging report is not a diagnosis.

What a finding means is understood by weighing together which organ it is in, its size, shape and internal structure, its enhancement characteristics, its change since previous examinations, the laboratory results and the patient’s symptoms.