Medical imaging, like MRI, CT, and ultrasound, plays a vital role in diagnosing HHT, formerly known as Osler-Weber-Rendu syndrome. Imaging can help guide treatment and improve your outlook with HHT.

Osler-Weber-Rendu syndrome, also known as hereditary hemorrhagic telangiectasia (HHT), is an inherited genetic disorder of the blood vessels.

In HHT, abnormal connections between arteries and veins form in multiple organ systems. These connections cause symptoms like telangiectasias of the skin and mucous membranes and internal arteriovenous malformations (AVMs). AVMs are prone to rupturing and bleeding, which can cause serious health consequences.

Because some people with HHT have very few symptoms, and disease manifestations may not appear until later in life, medical imaging plays a vital role in diagnosing HHT. Imaging can also help doctors monitor potentially dangerous AVMs and, when necessary, treat preventively to avert serious complications.

Diagnosis

Most people with HHT have a genetic mutation known to cause the disease. But in up to 10% to 15% of families with HHT, the mutation is unknown, meaning a genetic test cannot definitively rule out HHT.

For an HHT diagnosis, doctors usually need to observe three of the following four criteria, known as the Curaçao criteria:

  • recurrent spontaneous nosebleeds (affecting at least 95% of people with HHT)
  • multiple telangiectasias on the skin and mucous membranes
  • AVMs, often of the brain, liver, or lungs (which require medical imaging to detect)
  • history of HHT in a first-degree relative

Doctors consider people who meet two of the criteria to have “probable” HHT. Children and siblings of people with HHT are also at high risk. In these cases, a doctor may order screening medical imaging to detect possible internal AVMs.

Treatment

An HHT treatment plan might include imaging scans to:

  • monitor existing AVMs
  • detect new AVMs
  • determine when intervention is needed
  • follow up after treatment

If an AVM is very small or carries a low risk of causing future problems, a doctor may recommend serial imaging studies to continue monitoring it. For example, they may monitor small lung AVMs via chest CT every 3 to 5 years.

Imaging also guides preventive treatment decisions. For example, a doctor may consider the size of the artery feeding an AVM, its location, and other characteristics seen on imaging to prompt more definitive treatment procedures.

Imaging is also crucial in some procedures, such as treating higher risk brain and lung AVMs via coiling. During this procedure, doctors visualize proper positioning with injectable dye and X-rays before plugging or blocking the AVM with a metal coil to prevent bleeding or bursting. Without blood flow, the AVM may eventually shrink down on its own.

Doctors may use the following types of imaging tests to help diagnose and treat HHT:

  • MRI: Adding intravenous contrast and MR angiography can help doctors detect abnormal blood vessels. There’s no radiation involved, but testing is lengthy and may require sedation in young children.
  • Ultrasound: With Doppler technology, ultrasound can visualize the speed and turbulence of blood flow inside your blood vessels, especially the liver and kidneys. Special ultrasounds, like transthoracic contrast echocardiography (TTCE, aka “bubble study”), can assess for lung AVMs.
  • CT: CT is X-ray based high-resolution imaging ideal for detecting lung and liver AVMs. Doctors can add intravenous contrast and angiography to enhance images and improve the detection of AVMs in other locations.
  • Angiography: In contrast to CT or MR angiography, standard angiography uses a catheter threaded carefully through your blood vessels to the site of concern. It’s the gold standard for diagnosing AVMs but carries more risk than other imaging procedures.

Brain

Brain AVMs, which can cause seizures or strokes, occur in about 10% of people with HHT. They’re best seen on MRI.

Certain image sequences may show bright spots in areas of increased blood flow, indicating an AVM. Doctors can visualize the structure and pattern of your blood vessels and even detect signs of impending rupture like tiny hemorrhages.

Brain imaging can sometimes reveal other complications of HHT, such as tiny infarcts, abscesses, or mineral deposits.

Lung

Lung AVMs occur in at least 50% of HHT cases. The initial screening test for lung vascular malformations is a “bubble study.” Doctors inject a small amount of agitated saline into your vein. Then, they check whether saline bubbles appear in your left heart atrium.

Usually, tiny vessels connecting your arteries and veins (capillaries) destroy any bubbles. If bubbles show up in the left side of your heart, it could mean your blood hasn’t taken the regular path due to an AVM.

If your results are abnormal, doctors may obtain a chest CT to locate and detail the structure of any AVMs.

Liver

Problems with blood vessels in the liver occur in up to 75% of people with HHT, per some experts, but far fewer ever cause symptoms.

Doctors can detect liver AVMs with ultrasound, MRI, or CT. They usually start with ultrasound since it doesn’t involve radiation.

Using ultrasound, doctors can detect dilated liver veins and arteries with unusually fast blood flow, suggesting an AVM. They can also see changes in the size and texture of the liver and spleen, which might indicate a large liver AVM. Some people with HHT will also develop focal nodular hyperplasia or benign liver masses.

Gastrointestinal tract

Recurrent gastrointestinal (GI) bleeding occurs in about 15% to 20% of people with HHT, often starting in their 20s. But doctors detect most GI AVMs and telangiectasias with endoscopy rather than medical imaging.

What is the Osler-Weber-Rendu syndrome triad?

The “classic” HHT triad consists of recurrent nosebleeds, multiple skin and mucosal telangiectasias, and a family history of HHT. However, HHT symptoms can be highly variable, even in family members with the same genetic mutation.

What is the life expectancy of someone with Osler-Weber-Rendu syndrome?

With the combined benefits of diagnostic testing, monitoring, and effective treatments, most people with HHT who have access to healthcare can enjoy a near-typical life expectancy.

People who have not received a confirmed diagnosis of and proper treatment for the condition may have their life expectancy shortened by an estimated 3 to 7 years.

How rare is Osler-Weber-Rendu syndrome?

Experts estimate that HHT affects as many as 1 in 5,000 people in North America. Worldwide, the highest prevalence (about 1 in 1,330) of HHT is among Afro-Caribbean populations in the Netherlands Antilles.

Osler-Weber-Rendu syndrome, also known as HHT, is a rare inherited disorder of the blood vessels. Although symptoms can vary significantly from person to person, the most serious complications of HHT, such as stroke, massive bleeding, and heart or liver failure, often arise from AVMs.

Doctors can use imaging like ultrasound and angiography to detect and characterize AVMs. This helps guide HHT diagnosis, monitoring, and treatment, and can help reduce your risk of serious complications.

If you or your child have an HHT diagnosis, talk with your doctor about your medical imaging plan.