Case 11 - History of MVC

Case 10

This week's case was an example of intrahepatic biliary ductal dilation on ultrasound.  We see it so often in other modalities, but it's not as commonly seen on ultrasound, where we are supremely reliant on our technologists. If they don't see it and take an image of it, we usually won't see it.  Thankfully, in our protocols, our technologists are supposed to take cine sweeps through any pathology and certain structures, where we might catch things they miss.  Always look at the sweeps to look for missed pathology.

Two anechoic tubular structures, which is abnormal due to the intrahepatic bile duct dilation.

Remember this from histology? The portal triad

Remember: if you see two hypodense structures surrounding the portal vein, it's periportal edema, and it will extend along all branches of the portal vein. If you look at the left portal vein branch in this image, there is only 1 hypodense structure along the posterior aspect of the portal vein, meaning this is bile duct dilation. 

The CBD is also dilated. In this patient, this was all an expected sequela of prior cholecystectomy.

Case 10 - Abdominal pain

Case 9

This case demonstrates pneumoperitoneum, which was missed by a staff radiologist. When I saw this study, the first thing to catch my eye was the large lucency over the liver (star), especially since this was a supine radiograph. On a supine radiograph, you have to look for gas rising non-dependently along the anterior abdominal wall resulting in a "lucent liver sign."  Additionally, as most of the answers noted, there is free air revealing itself as a Rigler sign in the left hemiabdomen. There is a segment of small bowel where you can see both surfaces of the bowel wall - intraluminal and serosal surface (arrow). Turns out, this was a case of a perforated sigmoid cancer.

Radiopedia has a great list of all of the different signs of pneumoperitoneum and being familiar with them will help you in cases where you might not have a classic Rigler sign or an upright chest radiograph with subdiaphragmatic free air.

Sigmoid wall thickening with an abscess in the right anterior pelvis.

Case 9 - Abdominal Distension

Case 8 - "Locked Facets" (Cervical Spine Facet Joint Dislocation)

This case demonstrates bilateral cervical spine facet joint dislocation, which is commonly called jumped or locked facets.  Facet joint subluxation, perched facets, or locked facets all fall under the hyperflexion type of injury and can be unilateral or bilateral. When there is true facet joint dislocation, as was present in this case, you also have a translational injury as noted by the anterolisthesis of C6 on C7. In the setting of cervical spine trauma, a lot of trauma centers are performing a CTA of the neck as their initial cervical spine evaluation in order to asses for bony injury and associated vascular injury. If not performed, this patient would require a CTA of the neck as well.

When evaluating the cervical spine in the setting of trauma, I always start with the sagittal series because I want to be most attuned to looking for facet joint alignment and widening of the posterior elements of the spine, which is often quite subtle, more so than perched or locked facets. Facets are considered subluxed when there is less than 50% overlap of the articular surfaces or there is more than 2mm of diastasis.

Normal facet articulation on the axial images - the facet look like a hamburger  with two 'bony buns'

Reverse Hamburger Bun Sign - the facets are dislocated

Locked Facets - The red lines show where the superior and inferior facets should be articulating.

The arrows show the areas of bony avulsion from the vertebral body, which was ripped of by the anterior and longitudinal ligaments.

For further reading, this is a great radiographics article, which further describes cervical spine trauma and also delves into the SLIC morphology score for surgical vs. nonsurgical management.

MDCT of Blunt Cervical Spine Trauma in Adults (Dreizin, et al)