Mickey Mouse learning notes

"Mickey Mouse" view of Portal Triad - Emory emergency ultrasound department  7/17/2011

http://www.em.emory.edu/ultrasound/ImageWeek/mickey_mouse.html

This week’s image is brought to us by Dr. Haviland. It is a short axis, or "Mickey Mouse" view of the portal triad obtained as part of a biliary scan. Once the gallbladder is visualized in its long axis this view can be obtained by following the main lobar fissure, which has the appearance of a thin hyperechoic line extending from the neck of the gallbladder to portal vein. The portal vein appears as the dot at the base "exclamation point" formed  in this longitudinal view. With subtle fanning and adjustments of the probe the remaining structures of the portal triad (the hepatic artery and common bile duct) can be brought into view. Given the smaller size of these structures they often have the appearance of Mickey Mouse ears. If the probe indicator is towards the patient's right side, then Mickey's right ear should be the common bile duct. Given the absence of flow in the common bile duct, doppler imaging can be helpful to differentiate it from the portal vein and hepatic artery. Once this view is obtained the probe can be rotated 90 degrees to obtain a long axis view of the CBD for measurement.  Measurement should be taken from inner wall to inner wall of the CBD. Normal width of the CBD is 4mm for patients less than 50 with one additional mm allowed for every decade over 40. 

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III.  [Gallbladder] Scanning Technique and Normal Findings

http://www.sonoguide.com/biliary.html

Gallbladder: Curvilinear abdominal probes with a frequency ranging from 2-5 MHz are ideal for examination of the gallbladder.  The lower end of this range may be necessary for sufficient penetration in larger patients.  However, sonographers should increase the frequency whenever possible as the evaluation of wall thickness, pericholecystic fluid, and gallstones is significantly improved with better resolution.
The gallbladder is identified with three basic approaches: The “subscostal sweep” , the “X minus 7” and the "flattening the probe" approach.  The subcostal sweep is generally the most effective window and is usually attempted first.  Start the scan with the probe in longitudinal orientation and the probe-indicator oriented toward the patient’s head and instruct the patient to take a deep breath.  Sweep the probe inferiorly and laterally along the subcostal margin (Video 1).

Video clip 1:  Subcostal sweep video (includes audio).

The X-Minus 7 approach is an intercostal window.  Find the xiphoid process and move laterally to the right approximately 7 centimeter.  Place the probe perpendicular to the skin between the ribs.  In most cases, the gallbladder will be found posterior to the liver parenchyma immediately beneath the probe.  In the few instances where the gallbladder is not identified, move the probe laterally, sweeping through the liver (Video 2).

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