1. “What Test is Best” Choosing Radiology Exams in Emergency Settings
Dr. C. Freeman PGY-4
Dr. A. Olivier

2. Objectives
To provide a guide to selecting the appropriate imaging studies in common emergency settings
Please note: the goal of this talk is NOT to review how to read radiological exams.

3. Modalities Plain Films Ultrasound
Based on differential attenuation of X-rays by different tissues
Ultrasound
Uses sound waves
Real time
Very accessible
No radiation

4. CT Computer reconstruction of 2 dimensional X-ray data
reconstructions in any plane
Accessible, fast

5. WHAT IS A “SPIRAL CT”??????
Helical movement (patient and gantry move at the same time)
Almost all modern CT’s are helical
Exceptions: Head CT, High Resolution CT of the chest

6. Soft tissue differentiation (e.g. Soft tissue tumors)
MRI
Soft tissue differentiation (e.g. Soft tissue tumors)
many other specialized indications (e.g. acute stroke)
limited accessibility, expensive
Expanding role in many clinical situations

7. CHEST “the patient who is short of breath”
Common Causes…
CHF, atelectasis, pneumonia, pneumothorax, pulmonary embolus
start with a Chest X Ray

8. Atelectasis
Left diaphragm silhouetted
Left diaphragm now seen

9. Complete Collapse

10. Inspiration-expiration may increase sensitivity
Pneumothorax
Inspiration-expiration may increase sensitivity

11. Pneumothorax

12. Tension pneumothorax ***EMERGENCY
place needle in 2nd intercostal space (mid clavicular line)

13. Pneumonia
Air bronchograms
Silhouette sign

14. Pneumonia: Air Bronchogram

15. Congestive Heart Failure

16. Pulmonary Emboli CXR V/Q Scan CT Pulmonary Angiogram
non specific, non sensitive
V/Q Scan
useful if high probability or low probability
CT Pulmonary Angiogram

17. CXR: HAMPTON’S HUMP Chest X-ray not useful to rule in or rule out PE
BUT may help to find other cause of SOB (e.g. CHF)

18. V/Q Scan VENTILATION POSTERIOR PERFUSION LATERAL
High probability: Treat (anticoagulate)
Low probability: unlikely to have PE
Intermediate Probability: ??? CT Angiogram

19. CT ANGIOGRAPHY ACUTE THROMBOEMBOLI

20. Aortic Dissection CT
Trans-esophageal echo

21. CT Reconstruction: Aortic Dissection

22. GI/GU Again, begin with a plain film
Remember utility of upright and decubitus films for identifying free air and air fluid levels
Often move on to another exam depending on plain film findings

23. Free Air
^^^ ^
Upright Chest X-Ray is the most sensitive test for free air

24. Free Air: Decubitus View

25. FREE AIR
we see both sides of the bowel wall
“Riegler’s sign”

26. Plain Films CT IVP (ultrasound sometimes useful…e.g. if pregnant)
Renal Colic
Plain Films CT
IVP
(ultrasound sometimes useful…e.g. if pregnant)

27. Ureteric calculus
note how well a calcified stone is seen on plain films.

28. IVP Shows function and obstruction HOWEVER…largely replaced by CT
“Left flank pain”
IVP
Shows function and obstruction
HOWEVER…largely replaced by CT

29. Renal Colic: CT
Now Preferred Modality

30. RLQ Pain, Fever, WBC ……? Appendicitis
Plain film of limited utility
may see appendicolith
Ultrasound
No radiation
In females, can also see adnexa
Especially good in thin patients CT
If overweight

31. ..? Appendicitis
RLQ PAIN
appendicolith

32. Appendicitis: CT

33. “distended abdomen with obstipation and peritoneal signs”
Bowel Obstruction
start with a plain film
supine and upright views
lateral decubitus if upright not possible

34. Small Bowel Obstruction
Multiple air-fluid levels
distended bowel loops
note the value of upright (or decubitus) view

35. Large Bowel Obstruction: Contrast Enema
Confirms the site of abrupt narrowing at the splenic flexure (large arrow)

36. Bowel Obstruction…after the plain film
Depends on the clinical scenario
May monitor patient
May go directly to the Operating Room
May proceed to CT
helps to define location and cause of obstruction

37. Pancreatitis Clinical/Biochemical Diagnosis
Ultrasound to identify cause (i.e. biliary stones)
CT is used to identify and follow complications
***NOT TO DIAGNOSE
Will MISS diagnosis in 30% of cases

38. Scrotal Pain History and Physical first
May proceed directly to the OR
Ultrasound is the modality of choice
Can identify status of blood supply

39. Testicular Ultrasound

40. RUQ Pain Ultrasound is the modality of choice
CT can miss acute cholecystitis or cholelithiasis

41. Ultrasound: Cholelithiasis

42. Neuroradiological Emergencies
Start with a CT
**Except cord compression
May ultimately need an MRI

43. Clinical Settings
Seizures
Trauma
Headache
Stroke

44. Seizures: CT---Neoplasm

45. Seizure: MRI---Neoplasm

46. CT: Stroke Some advanced CT techniques …”CT Perfusion” helpful
In the USA, many centers MRI is the initial exam
Some specialized MRI Techniques can identify brain at risk (“penumbra”) vs. dead brain

47. CT Intra - Cranial Bleeds Subarachnoid Hemorrhage Subdural Hemorrhage
Epidural Hemorrhage

48. CT: Subarachnoid Hemorrhage

49. Epidural Hematoma

50. Subdural Hematoma

51. SPINE Emergencies

52. C-Spine Trauma Plain films: CT MRI
If minor trauma, plain films including flexion and extension views can suffice CT
For significant injury
From skull base to T1
Sagital and coronal reconstructions
MRI
Unexplained neurologic deficit
Unconscious for prolonged period of time

53. Normal C-Spine with CT
Axial
Sagital
Coronal

54. Hangman’s #
Axial
Sagital

55. C5-6 dislocation
Axial
Sagital

56. MR Angiogram
C5-6 dislocation with
Left Vertebral Artery dissection

57. Suspected Spine Infection
Plain films
may be diagnostic
Do not demonstrate compression of thecal sac
MRI is optimal
CT can be adequate
Fluoroscopic or CT guided aspiration/biopsy
We follow these cases with MRI

58. Discitis
Discitis,
Sagital
Coronal
Axial

59. Discitis, osteomyelitis prevertebral & epidural phlegmon

60. Cord Compression: MRI
Metastatic Melanoma

61. Spine Emergencies: Summary
MRI is generally the best exam for the spine
CT is excellent in many indications
Plain films have a limited role
MRI access is quite limited, so we compromise and do a lot more CT

62. MSK

63. Fractures
Remember that acute fractures may not be seen on plain films for up to days.
Bone scan is more sensitive

64. Plain Film: Ankle Fracture

65. Sacral Fracture: CT

66. ? Septic Joint Plain film may be suggestive MUST aspirate joint
This is a medical emergency

67. Necrotizing Fasciitis
Ultimately a clinical diagnosis
Plain Films
Gas in the soft tissues
MRI
For surgical planning
CT may give a false negative (not sufficient to rule out diagnosis)

68. Summary Almost always start with the plain film
There are some exceptions
Neurological Emergencies
If you are unsure as to what test is appropriate…talk to the Radiologist

69. Thank you!!
Dr. C. Freeman
Dr. A. Olivier