Radiology in the Setting of Trauma

Question 1

Radiology “trauma series”

Answer 1

AP supine CXR;

X-table lateral C-spine;

AP supine pelvis

Question 2

Trauma protocol CT

Answer 2

Head and C-spine CT without contrast, followed by a contrast CT chest/abdomen/pelvis

Question 3

Why is CT so much better than x-ray for finding pneumothorax in the case of trauma?

Answer 3

Because the patient is lying down! This means that the air rises to the chest wall and is obscured on a plain film.

You need 3 dimensional imaging to detect that air if the patient is supine.

Question 4

Main indications for trauma protocol CT

Answer 4

1. Major trauma case
2. Not possible to obtain patient history (inebriation, unconscious, etc)

Question 5

You have a trauma patient with widened mediastinum on CXR. You suspect aortic disection and want to confirm, but the patient’s labs came back with a Cr of 3.6. What do you do?

Answer 5

Rather than CT, do a transesophageal ultrasound.

MRI is a theoretical anternative, but usually in trauma cases the acuity does not permit time for an MRI scan.

Question 6

CT findings of traumatic aortic dissection

Answer 6

• Widened mediastinum with fluid opacities
• Intimal flap visualized within the aorta
• Focal bulge
• Pseudoaneurysm
• Mediastinal hematoma (usually at the level of the ligamentum arteriosum)

Question 7

Traumatic aortic injury vs aortic dissection

Answer 7

• Traumatic aortic injury: Multiple presentations –
  
  • Aortic laceration is a tear in the intima and aortic transection is a tear of all three layers of aorta and can result in aortic rupture.
  • Aortic pseudoaneurysm is a contained localized rupture. The pseudoaneurysm is contained by an intact adventia.
  • Intramural hematoma represents localized bleeding in the wall of the aorta.
  • Localized dissection can occur at the site of aortic injury but this is uncommon.
• Aortic dissection: Aortic dissection results from a tear in the intima, resulting in two channels of flowing blood. An aortic dissection can rupture and allow blood to extravasate into the pleural space or mediastinum, although most are diagnosed unruptured.

Question 8

Upper limit of normal for defining ascending aortic aneurysm

Answer 8

< 4 cm is normal for ascending aorta

> 4 cm is an abscending aortic aneurysm

Question 9

Deep sulcus sign

Answer 9

It is very hard to identify pneumothorax from a supine radiograph.

This is one of the ways that you can.

On a supine radiograph, the deep sulcus sign may be the only suggestion of a pneumothorax because air collects anteriorly and basally, within the non-dependent portions of the pleural space, as opposed to the apex when the patient is upright. Thus, the costophrenic angle is abnormally deepened and often radiolucent.

Question 10

Studies in the setting of suspected rib fracture

Answer 10

AP CXR is first line in most cases.

However, if you suspect splenic rupture, don’t waste your time: Get an abdominal CT.

Also, if abuse or malignancy is suspected, you may consider getting a dedicated rib film in addition to (not instead of) an AP CXR.

Question 11

What is going on in this CXR?

Answer 11

Pneumomediastinum

Look very closely at the left mediastinal-pleural border, and on the lateral thoracic inlet in the neck.

Question 12

Subpleural blebs

Answer 12

Blebs of trapped air underneath the pleura, inside of the mediastinum.

When someone suffers trauma, often a fall, they may rupture and result in spontaneous pneumomediastinum or pneumothorax. This usually resolves spontaneously as the air is gradually resorbed.

Same as discussed w/ Marfan syndrome and related syndromes – it’s just whether or not they happen to be mediastinal.

Question 13

Patient arrives following blunt abdominal trauma. FAST scan is negative for abdominal fluid. What is the next step?

Answer 13

Depends on the clinical context.

If the suspicion for bleed is low and the patient does not have any abdominal symptoms (pain, tenderenss) or volume loss (delayed capillary refill, decreased peripheral pulses), you are done looking for a bleed.

If any of the above are present, you should do an abdominal CT, which is much more sensitive for bleeding.

Question 14

Where does a FAST scan look?

Answer 14

• Perihepatic
• Perisplenic
• Pelvic
• Pericardiac

Question 15

Rule of thumb for solid abdominal organ truama management

Answer 15

• If the patient is hemodynamically stable and there is no evidence if active bleed (even if a hematoma is present), then nonoperative management is preferred.
• If unstable or actively bleeding from the spleen or liver, embolize or take for open repair
• If the patient is stable but over age 70, consider taking to OR anyway (may rapidly decompensate)
• Any diaphragmatic, bowel, or mesenteric injury is an indication for surgical management.

Question 16

Systematic approach to assessing for pelvic bone trauma

Answer 16

1. Check that the three rings are intact (2x obturator, main pelvic ring)
2. Make sure that the pubic symphysis is not widened (should be < 1 cm)
3. Check the sarcoiliac joints (symmetry, width)
4. Assess the proximal femur for dislocation and fracture

Question 17

Use of CT contrast in the acute setting

Answer 17

• IV is almost always used (but do head prior to administering to rule out intracranial bleed)
• Oral is never uesd
• Rectal is used only if there is pelvic injury with suspicion for rectal/sigmoid colon injury (in which case extravasation of contrast indicates injury)

Question 18

Barium in imaging of hollow viscus

Answer 18

Very useful, but if it gets into the pleural or peritoneal space it may never be resorbed

Attached is an image who had a barium study with a bowel leak 15 years after this incident.

Question 19

What is going on in this CT of a trauma patient?

Answer 19

A duodenal hematoma

Look closely: That’s not the spleen.

This is a common seatbelt injury in children.

Question 20

Assessing for urethral vs bladder injury

Answer 20

If there is blood at the urethral meatus, a retrograde urethrogram must be performed to rule out urethral injury prior to further bladder imaging (since they all involve sticking something up the urethra)

If the above doesn’t detect anything or if there is just no blood at the meatus, you can proceed to insert a Foley catheter, distend the bladder, and then perform either a CT cystogram or a retrograde cystogram. CT is preferred (less invasive, higher sensitivity)

If there is blood at the meatus but no urethral injury, then there is almost certainly a bladder injury.

Question 21

What is going on in this CT?

Answer 21

There is a left perinephric hematoma

Often these are observed if the patient is hemodynamically stable.

Sometimes large perinephric hematomas can compress the kidney and impair its function and/or cause hypertension, so this should be followed via labs and serial ultrasound if nonoperative management is attempted.

Question 22

What is going on in this trauma patient’s CXR?

Answer 22

Diaphragmatic rupture

Those are faint bowel loops that you are seeing in the left hemithorax, and an accompanying rightward shift of the trachea and mediastinum.

Question 23

Which side of the diaphragm is more likely to rupture in trauma?

Answer 23

The left. Overwhelmingly the left.

This is because the liver serves as a giant shock absorber for the right hemidiaphragm.

The spleen isn’t so good at that.

Question 24

Endovascular aortic repair limitations and complications

Answer 24

• Prerequisites:
  
  • Aneurysm below the level of the renal arteries
  • Suitable anatomy (ie, iliacs aren’t so stenosed that we can’t get to the AAA via the groin)
• Complications:
  
  • Endoleaks (highest probability in first ~15 months. Screen at 3 months, 15 months)
  • Endograft migration
  • Graft rupture
  • Graft limb stenosis