General suggestions in ordering body CT in ED; vascular occlusion; aneurysm/pseudoaneurysm; bleeding and active contrast extravasation; extraluminal air

1. Body CT
for Emergency Physicians
Rathachai Kaewlai, MD
Division of Emergency Radiology
Department of Radiology, Ramathibodi Hospital, Bangkok,Thailand
Annual Conference ofThai Emergency Physicians (ACTEP)
25 Nov 2015 at the Regent Cha-am Beach Resort, Cha-am, Petchaburi,Thailand

2. Outline
About emergent body CT
Vascular occlusion
Aneurysm/pseudoaneurysm
Bleeding and active contrast extravasation
Extraluminal air

3. CT Contrast: Update
Post contrast acute kidney injury (PC-AKI)
Creatinine change in 48 hours after IV contrast
Various etiologies: physiologic variation, drugs, CM
Contrast induced nephropathy (CIN)
Subset of PC-AKI
Exists but likely rare, unknown prevalence
eGFR more commonly used than serum creatinine

4. CT Contrast: Update
21346 patients undergone CT, half received IV contrast
1:1 matched on propensity score yielding similar demographics
and comorbidities
Radiology
December 2014

5. IV Contrast: When?
Chest: most emergent indications
Abdomen: most emergent indications except ureteric
stone, R/O AAA rupture, R/O free air
CTisUS.com

6. Oral Contrast: When?
Generally not recommended in ER setting except for
Penetrating abdominal trauma
Suspected GI fistula, postoperative leakage
Suspected esophageal perforation
Take time (1-2 hours)
Value questioned even in suspected bowel perforation
Role of “limited” oral contrast?
emrap.org

7. Rectal Contrast: When?
Generally not recommended in ER setting except for:
Penetrating abdominal trauma
Suspected GI fistula, postoperative leakage
May be used in
Suspected appendicitis esp in children
Workflow and job issue
Patient discomfort
oakmed.co.uk

8. Timing of Acquisition:
What Why?
NCCT
CTA
arterial
venous
delayed
ARTERIAL
VENOUS
CTA

9. Scan Coverage: CTA Aorta
Whole aorta
R/O dissection (assess extent)
R/O aortic aneurysm w/o prior
imaging (potential coexisting
aneurysms)
One part OK
R/O AAA rupture
F/U known aneurysm

10. Scan Coverage: CTA for PE
With lower extremity (LE) CTV
Older patients
No worry on volume of IV contrast
(kidneys, CHF)
Without LE CTV
Younger patients
Do Doppler (similar accuracy as CTV)
ehumanbiofield.wikispaces.com

11. Scan Coverage: Abdominal CT
Most ER indications !
whole abdomen
Pancreatitis
Colon problems
Upper abdomen:
Hepatobiliary problems
Lower abdomen:Appendix
KUB: Stone protocol

12. Scan Coverage: Multiphase CT
Should avoid in young patients (45 years)
For most ER indications, venous phase is enough
Pretty much depending on your radiologists’ level of
comfort and experience
Required for
Bowel ischemia
Characterization of masses or suspected masses

13. Scan Coverage: Non-contrast
Do we always need non-contrast before giving IV CM?
No!
Most people worries that IV contrast will obscure
blood and Ca2+, it’s partly true BUT we can still
diagnose blood and dense Ca2+ on post-contrast CT
We do this if it is multiphase scan
Bowel ischemia
Characterization of masses or suspected masses

14. NCCT Only
eGFR 30 without dialysis unless risk accepted by
referring physician and patient
Acute flank pain
R/O AAA rupture
May need IV contrast if patient’s conditions allow
R/O free air
Looking for lung lesions, bone lesions

15. Scan Coverage: Trauma CT
Trauma CT is different than other CTs
Coverage: torso coverage in abdominal trauma
Arterial phase necessary: active contrast
extravasation
No need for non-contrast phase
Reduced radiation dose because many trauma victims
are young (higher risk of radiation-induced cancers)

16. Approach to CT Interpretation
Clinical question first ! look for pathology suspected
Then ! systematic review of images
Check blind spots of each exam
(Knowing body anatomy is a prerequisite!)

17. Critical CT Findings
Vascular occlusion
Bleeding and active contrast extravasation
Extraluminal air

18. VASCULAR OCCLUSION
“Filling defect” and mimics
Acute vs. non-acute occlusion
Effects of occlusion

19. Intravascular Filling Defect
Intraluminal filling defect(s)
with sharp interface with
intravascular contrast
material
Acute pulmonary emboli

20. SMA/SMV Thrombus
Superior mesenteric artery thrombus
Superior mesenteric vein thrombus
with bowel dilatation/thickening, likely
ischemia

21. Deep Vein Thrombosis
DVT of the left femoral vein

22. Pseudo-filling Defect
Not sharp
Not that hypodense
Outside vessels
Pseudo-filling defect in bilateral femoral veins
2/2 heterogeneous contrast opacification
Interlobar lymph nodes

23. Acute Filling Defect
Peripheral filling defect acute angled with arterial wall
Partial, central filling defect
Polo mint
Railway tract
Normal or enlarged vessel diameter
Perivascular soft tissue stranding

24. Changes 2/2 Occlusion
Proximal to site of vascular occlusion – high pressure
At site of vascular occlusion – attempt to reperfuse
Distal to site of vascular occlusion – infarction
(proximal/distal = relative to blood flow)

25. ANEURYSM/
PSEUDOANEURYSM
Fusiform vs. saccular
Rupture?
Infected?

26. Aneurysm/pseudoaneurysm:
Definitions
Fusiform 1.5X of
expected diameter
Any saccular and pseudo-
(1.1x-1.4x = ectasia)
UFHealth.org

27. Pseudoaneurysm: Aortic Injury
*
*
Pseudoaneurysm with surrounding hematoma
of the proximal descending
thoracic aorta 2/2 blunt trauma

28. Fusiform Aneurysm: Aorta
Thoraco-abdominal fusiform aneurysm
with partial thrombosis and ulcer within
the thrombus
Partially thrombosed AAA

29. Saccular Aneurysm: Aorta
Saccular aneurysm of the aortic arch with partial thrombosis

30. “Impending” AAA Rupture
Hyperdense crescent
Sensitivity 77%, specificity
93%, PPV 53%
Focal discontinuity of intimal
calcification
Tangential calcium sign
Bottom-row images from Radiologyassistant.nl

31. BLEEDING AND ACTIVE
CONTRAST EXTRAVASATION
Blood density on CT
Blood in free spaces and confined spaces
Active bleeding

32. Blood on CT
Shades of gray
Air Fat CSF Water CM Bone Metal
-1000 0 15 1000 HU
Description relative to organs where blood is located
CT attenuation of blood products depends on location,
mixture (i.e., with CSF), initial hematocrit and time from
onset of bleeding

33. Hematocrit Effect
35-45
HU
Whole blood = cells + plasma
55-65%
Plasma
Erythrocytes
35-45%
Leukocytes
And
platelets
0-10 HU
60-90 HU

34. Location of Blood
Potential spaces
Pleural, pericardial, peritoneal
Confined spaces (organs, structures)
Mediastinum, chest wall
Solid organs
Hollow viscus

35. Hemothorax
Mostly from trauma
Hemithorax holds up to
4L – enough for
exsanguination
Clotting may occur quickly
Traumatic left hemothorax
*

36. Mediastinal Hemorrhage
Trauma
Vascular/cardiac rupture
and dissection
Coagulopathy
Traumatic aortic pseudoaneurysm
“Traumatic aortic injury”
*

37. Hemoperitoneum
Most dependent portions
Abdomen: hepatorenal
Pelvis: cul-de-sac
Ruptured ovarian cyst
*
*
*

38. Sentinel Clot
Clots develop at site of
bleeding (sentinel)
Higher density (45-80 HU)
compared to blood
elsewhere (25-45 HU)
Probable site of bleeding
Ruptured GI stromal tumor of stomach
**
*

39. Retroperitoneal Hemorrhage
Around retroperitoneal
organs/structures
Ruptured AAA
*
*

40. Active Contrast Extravasation
Jet or focal area of contrast
in hematoma
High density mostly 100 HU
*
*

41. Active Contrast Extravasation
Changing appearance and/or density on delayed images
*
*
*
*
*
*

42. Active Contrast Extravasation
Significant bleeding
May require IV fluid, blood transfusion, embolization or
surgery depending on clinical factors lifesaving
surgical or endovascular Rx

43. EXTRALUMINAL AIR
Air in extraluminal spaces
Mimics

44. Extraluminal Air
“Something bad is going on.”
Mostly indicative of surgical emergency
CT best to detect small extraluminal air and may be
able to define the etiology

45. Pneumothorax
Gas in pleural cavity thru
chest wall or lung
across visceral pleura
No lung tissues
Much lower density
(lower than -1000 HU)
CT most reliable for
diagnosis but should not
be routine
*
*

46. Pneumothorax
Look for signs of possible tension on CT - best on coronal view
Mediastinal shift to contralateral side, flat/inverted diaphragm
“Clinical” diagnosis
*
*
*
*
*
*

47. Pneumothorax
Supine position – anterior,
medial location
*

48. Pneumomediastinum
Sources:
Airways
Esophagus
Lungs
Track from neck or
abdomen
Presumed alveolar rupture – Macklin effect

49. Pneumomediastinum
Concerning if:
Fluid in mediastinum
Localized around
airways or esophagus
Leakage of esophageal
contrast
Spontaneous esophageal perforation
*
*

50. Pneumopericardium
Thoracic surgery
Pericardial drainage
Trauma
Gas-forming infection
Fistula to esophagus/
stomach
Image from Polhill et al. JTrauma 2009; 66(4)
*
*

51. In the Abdomen:
Perforated duodenal ulcer
Colonic pneumatosis
Look for
extraluminal air
in lung window

52. Intraperitoneal vs. Retroperitoneal
52
*
*
*
*
Intraperitoneal air. Smallest amount in the
anterior, non-dependent portion, mostly
in RUQ
Retroperitoneal air outlining
retroperitoneal organs

53. Pneumatosis vs. Intraluminal
53
Pneumatosis intestinalis – colon
Air in the wall, dependent portion,
separated from luminal content
Small bowel feces in the lumen of small bowel loops

54. Portal Venous vs. Biliary Air
54
Portal venous gas
With
pneumatosis,
PVG
is
likely
2/2
necro?c
bowel
Pneumobilia
Common:
Incompetent
sphincter
of
Oddi,
recent
instrumenta?on:
ERCP,
surgery,
fistula
with
GI
tract
Rare:
gas-­‐forming
infec?on
Periphery of liver
More branching
Central of liver
Few number of branches

55. Intraperitoneal Air
Perforation Site
Amount
Location
Stomach/duodenum
Abundant
Around liver and stomach
Small bowel
Small
Mesenteric folds, around liver
Appendix
Small/absent
Around appendix
Large bowel
Variable
Pelvis, mesenteric folds,
retroperitoneal space

56. Retroperitoneal Air
Perforation of:
Duodenum
Colon: asc/descending
Rectum
Post retroperitoneal Sx

57. Pneumatosis Intestinalis
Variables1
Odds ratio
Peritoneal signs
9.40
Age 60 years
3.00
Portal venous gas and
pneumatosis
2.52
Ascites
1.92
1Hani MB, et al. J Surgical Res 2013;185:581.
! Utility of CT appearance
questioned
! Mesenteric fat stranding
! Bowel wall thickening

58. Where Air Is Coming From?
Outside
Trauma
Iatrogenic
Produced there
Gas-forming infection
Nearby organs/structures
Fistula to/from air-containing structures
Extension from contiguous organs/structures

59. Summary
Tips on ordering body CT in ER discussed
Critical CT findings shown and discussed
Vascular occlusion
Aneurysm/pseudoaneurysm,
Blood and active contrast extravasation
Extraluminal air

60. THANK YOU FOR YOUR
ATTENTION