Imaging Liver Masses
1. Liver Abscesses: Abscesses may be single or multiple. They are characterized by a hypoechoic fluid collection with a hyperechoic shaggy wall. Early on the abscess contents may be close in echogenicity to the liver parenchyma, but as the contents liquefy further, the fluid becomes hypoechoic or even anechoic.
2. Hemangiomas: Hemangiomas are the most common primary tumor of the liver and are usually solitary. The are quite hyperechoic, often appearing bright white, and are also homogenous and well circumscribed.
3. Metastases: Metastases may be single or multiple. They may be of similar echogenicity to the liver, but in a more heterogeneous pattern. Often liver metastases or primary liver masses are more echoic that the liver due to increased vascularity.
4. Cysts: Liver cysts may be single or multiple. They are usually benign when they have thin walls and an anechoic fluid center. Posterior enhancement may be noted.
5. Gallbladder Stones & Polyps: For a good case example see the November 2009 issue of Soundings or check it out at www.erpocketbooks.com
6. During a focused bedside ultrasound, you may happen to come across a liver mass during the scan. The liver is an excellent acoustic window, so many bedside ultrasound applications will provide you with a great view of the liver parenchyma. Although EM physicians are not typically trained to make “formal” interpretations of liver sonograms, it is useful to understand some hepatic ultrasound basics so that the appropriate management decisions can be made. When a liver mass is discovered during a focused, bedside scan, explain to the patient the limitations of your scan, and ensure that appropriate, comprehensive imaging is arranged for a definitive diagnosis.
7. Practice Makes Perfect: With bedside ultrasound there is no substitute for experience. The more ultrasounds you do, the better you will be able to differentiate abnormal from normal, even when you may not be sure exactly what the abnormality is.
An image library of normal and abnormal ultrasounds helps immensely, and we can help. Just click on the ultrasound library link within the Real-Time Readings department.
Brady Pregerson manages a free online EM Ultrasound Image Library and is the editor of the Emergency Medicine Pocketbook series. For more information visit ERPocketBooks.com
Teresa Wu is the EM Ultrasound Director and Co-Director for Simulation Based Training for the Maricopa Emergency Medicine Program in Phoenix, Arizona.