A pseudoaneurysm, also known as a false aneurysm, is a collection of blood that forms outside the arterial wall, due to a breach in the vessel wall. Ultrasound is commonly used to diagnose and assess pseudoaneurysms, and there are certain features that may be observed during an ultrasound examination. These features can help differentiate pseudoaneurysms from true aneurysms and other vascular abnormalities. Here are some ultrasound features of pseudoaneurysms:
- Color Doppler Imaging:
- Pulsatile flow: Pseudoaneurysms often exhibit turbulent, pulsatile flow, which can be visualized using color Doppler imaging. This is in contrast to the laminar flow seen in normal vessels.
- Yin-Yang Sign:
- The "Yin-Yang" sign is a characteristic finding in pseudoaneurysms. It refers to the alternating colors seen on color Doppler, indicating bidirectional blood flow into and out of the pseudoaneurysm.
- Thrombus or Hematoma:
- Pseudoaneurysms may contain thrombus or hematoma within the sac, and this can be visualized on ultrasound as echogenic material.
- Neck Visualization:
- Pseudoaneurysms typically have a neck connecting the sac to the parent vessel. The neck is an important feature in distinguishing pseudoaneurysms from true aneurysms.
- Dynamic Assessment:
- Real-time or dynamic ultrasound imaging can be used to observe changes in the size and shape of the pseudoaneurysm during the cardiac cycle.
- Compression Technique:
- Applying gentle pressure with the ultrasound probe over the suspected pseudoaneurysm can help in the compression technique. A pseudoaneurysm may collapse or change in shape under compression.
Common locations for Pseudoaneurym
- Femoral Artery:
- Pseudoaneurysms at the site of femoral artery punctures are relatively common, often as a complication of procedures such as dialysis access, cardiac catheterization or arterial angiography.
- Radial Artery:
- Similar to the femoral artery, pseudoaneurysms can occur at the site of radial artery punctures, which are common in procedures like transradial cardiac catheterization.
- Brachial Artery:
- Pseudoaneurysms can develop in the brachial artery, typically as a result of trauma, injury, or iatrogenic causes.
- Carotid Artery:
- Although less common, pseudoaneurysms can occur in the carotid artery, often due to trauma or injury.
- Popliteal Artery:
- Pseudoaneurysms may form in the popliteal artery, and these can be associated with trauma or complications following surgical procedures in the popliteal region.
- Iliac Artery:
- Pseudoaneurysms can develop in the iliac arteries, and these may be associated with trauma, surgery, or other vascular interventions.
- Arteriovenous Fistulas:
- Pseudoaneurysms may also be associated with arteriovenous fistulas, where an abnormal connection forms between an artery and a vein.
- Visceral Arteries:
- Pseudoaneurysms can occur in visceral arteries such as the splenic, hepatic, or renal arteries, often due to trauma, necrosis, vasculitis, or complications of medical procedures.
- Peripheral Arteries:
- Pseudoaneurysms can occur in various peripheral arteries, especially in areas susceptible to trauma or iatrogenic injury.
Imaging tips and pitfalls
- Image all cystic lesion with color doppler; this may turn out to be a vascular structure
- Clinical correlate of pancreatitis, recent biopsy or any other iatrogenic vascular injury may be complicated with a pseudoaneurysm.
- Identify the pseudoaneurysm neck if possible.
It's important to note that while ultrasound is a valuable tool for the diagnosis of pseudoaneurysms, other imaging modalities such as computed tomography (CT) angiography and magnetic resonance angiography (MRA) may also be used for further evaluation, especially in complex cases or when detailed anatomical information is required. Additionally, the interpretation of ultrasound findings should be performed by trained and experienced medical professionals.
Case initially published on Radiopedia