1. CT Basic & Neuroradiology
Sianny Suryawati
Radiology Department, Faculty of Medicine
Wijaya Kusuma University Surabaya
2014

2. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

3. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

4. Neuroradiology Plain Film CT US MRI Interventional Nuclear Medicine
Angiography
Myelography
Biopsy
Nuclear Medicine

5. CT Basics

6. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

7. CT History SIR GODFREY N. HOUNSFIELD
1979 Nobel Laureate in Medicine

8. CT History 1972 – First clinical CT scanner Used for head examinations
Water bath required
80 x 80 matrix
4 minutes per revolution
1 image per revolution
8 levels of grey
Overnight image reconstruction

9. CT History 2004 – 64 slice scanner 1024 x 1024 matrix
0.33s per revolution
64 images per revolution
0.4mm slice thickness
20 images reconstructed/second

12. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

13. CT Protocolling What happens when an exam is requested?
A requisiton is completed.
The requested exam is protocolled according to history, physical exam and previous exams.
The patient information is confirmed.
The exam is then performed.
Images are ready to be interpreted in …
Uncomplicated exam – 5-10 minutes after completion
Complicated exams with reconstructions take at least 1 hour but usually 1-2 hours.

14. CT Protocolling CT head protocols With or Without contrast CT Brain
CT Brain with posterior fossa images
CT Angiogram/Venogram
CT Perfusion
CT of Sinuses
CT of Orbit
CT of Temporal bones
CT of Mastoid bones
CT of Skull
CT of Face

15. CT Protocolling Variables Plain or contrast enhanced Slice positioning
Slice thickness
Slice orientation
Slice spacing and overlap
Timing of imaging and contrast administration
Reconstruction algorhithm
Radiation dosimetry

16. CT Protocolling Patient Information Is the patient pregnant?
Radiation safety
Can the patient cooperate for the exam?

17. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases (Stroke)

18. CT Terminology Exams using Ionizing radiation Plain film CT
1/10 of all exams
2/3 OF RADIATION EXPOSURE
Fluoroscopy
Angiography, barium studies
Nuclear medicine
V/Q scan, bone scan

19. CT Terminology Attenuation Attenuation is measured in Hounsfield units
Hyperattenuating (hyperdense)
Hypoattenuating (hypodense)
Isoattenuating (isodense)
Attenuation is measured in Hounsfield units
Scale to 1000
-1000 is air
0 is water
1000 is cortical bone

20. CT Terminology What we can see The brain is grey
White matter is usually dark grey (40)
Grey matter is usually light grey (45)
CSF is black (0)
Things that are brite on CT
Bone or calcification (>300)
Contrast
Hemorrhage (Acute ~ 70)
Hypercellular masses
Metallic foreign bodies

21. CT Terminology Voxel Volume element Partial volume averaging
A voxel is the 2 dimensional representation of a 3 dimensional pixel (picture element).
Partial volume averaging

22. CT Terminology

23. CT Terminology Window Width Level or Center
Number of Hounsfield units from black to white
Level or Center
Hounsfield unit approximating mid-gray

24. CT Terminology

25. CT Artifacts

26. CT Terminology
Digital reading stations are the standard of care in interpretation of CT and MRI.
Why?
Volume of images
Ability to manipulate and reconstruct images
Cost

27. CT Terminology DICOM Digital Imaging and Communications in Medicine
DICOM provides standardized formats for images, a common information model, application service definitions, and protocols for communication.

28. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

29. Contrast
Barium
Iodinated
vascular
Biliary, Urinary
CSF
Gadolinium

30. Contrast Types of iodinated contrast
Ionic
Nonionic - standard of care
No change in death rate from reaction but number of reactions is decreased by factor of 4.
If an enhanced study is needed, patient needs to be NPO at least 4 hours and have no contraindication to contrast, ie allergy or renal insufficiency.

31. Contrast What are the risks of iodinated contrast? Contrast reaction
1 in 10,000 have true anaphylactic reaction
1 in 100,000 to 1 in 1,000,000 will die
Medical Issues
Acute renal failure
Lactic acidosis in diabetics
If on Glucophage, patient must stop Glucophage for 48 hours after exam to prevent serious lactic acidosis
Cardiac
Extravasation

32. Contrast Who is at risk for an anaphylactic reaction?
Patients with a prior history of contrast reaction
Patients with a history asthma react at a rate of 1 in 2,000
Patients with multiple environmental allergies, ie foods, hay fever, medications
Amin MM, et al. Ionic and nonionic contrast media: Current status and controversies.
Appl Radiol 1993; 22:

33. Contrast Pretreatment for anaphylaxis
50 mg Oral Prednisone 13, 7 and 1 hour prior to exam
50 mg oral Benedryl 1 hour prior to exam
In emergency, 200 mg iv hydrocortisone 2-4 hours prior to exam

34. Contrast
What are the risk factors for contrast induced acute renal failure?
Pre-existing renal insufficiency
Contrast volume
Dehydration
Advanced age
Drugs
Multiple myeloma
Cardiac failure

35. Contrast Considerations in patients with renal insufficiency
Is the exam necessary?
Is there an alternative exam that can answer the question?
Decrease contrast dose

36. Contrast Pretreatment for renal insufficiency Hydration Mucomyst
600 mg po BID the day before and day of study
Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine.
Tepel M, et al. N Engl J Med 2000 Jul 20;343(3):180-4

37. Contrast Contrast induced renal failure
Elevated creatinine hours after contrast which resolves over 7-21 days.
Can require dialysis
Mehran, R. et al. Radiocontrast induced renal failure:Allocations and outcomes.
Reviews in Cardiovascular Medicine Vol. 2 Supp

38. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

39. Radiation Safety
Diagnostic CT Scans: Assessment of Patient, Physician, and Radiologist Awareness of Radiation Dose and Possible Risks
Lee, C. et al. Radiology 2004;231:393

40. Radiation Safety Deterministic Effects Stochastic Effects
Have a threshold below which no effect will be seen.
Stochastic Effects
Have no threshold and the effects are based on the dose x quality factor.

41. Radiation Safety Terminology Gy = Gray is the absorbed dose (SI unit)
The equivalent of 1 joule/kg of tissue
Rad = radiation absorbed dose
Sv = Sievert is the dose equivalent (SI unit)
Absorbed dose multiplied by a quality factor
Rem = radiation equivalent man

42. Radiation Safety Relative values of CT exam exposure
Background radiation is 3 mSv/year
Water, food, air, solar
In Denver (altitude 5280 ft.) 10 mSv/year
CXR = 0.1 mSv
CT head = 2 mSv
CT Chest = 8 mSv
CT Abdomen and Pelvis = 20 mSv
-The equivalent of 200 CXR

43. Radiation Safety Effects of X rays.
Absorption of photons by biological material leads to breakage of chemical bonds.
The principal biological effect results from damage to DNA caused by either the direct or indirect action of radiation.

44. Radiation Safety Tissue/Organ radiosensitivity Fetal cells
Lymphoid and hematopoietic tissues; intestinal epithelium
Epidermal, esophageal, oropharyngeal epithelia
Interstitial connective tissue, fine vasculature
Renal, hepatic, and pancreatic tissue
Muscle and neuronal tissue

45. Radiation Safety
Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT
David J. Brenner, et al. AJR 2001; 176:
Additional 170 cancer deaths for each year of head CT in the US.
140,000 total cancer deaths, therefore ~ 0.12% increase
1 in 1500 will die from radiologically induced cancer

46. Radiation Safety 3094 men received radiation for hemangioma
Those receiving >100 mGy
Decreased high school attendance
Lower cognitive test scores
Per Hall, et al. Effect of low doses of ionising radiation in infancy on cognitive function in adulthood: Swedish population based cohort study BMJ, Jan 2004; 328:

47. Radiation Safety Hiroshima and Nagasaki
There has been no detectable increase in genetic defects related to radiation in a large sample (80,000) of survivor offspring, including: congenital abnormalities, mortality (including childhood cancers), chromosome aberrations, or mutations in biochemically identifiable genes.
William J Schull, Effects of Atomic Radiation: A Half-Century of Studies from Hiroshima and Nagasaki, 1995.

48. Radiation Safety Hiroshima and Nagasaki
However, exposed individuals who survived the acute effects were later found to suffer increased incidence of cancer of essentially all organs.
William J Schull, Effects of Atomic Radiation: A Half-Century of Studies from Hiroshima and Nagasaki, 1995.

49. Radiation Safety Hiroshima and Nagasaki
Most victims with high doses died
Victims with low doses despite their large numbers are still statistically insignificant.

50. Radiation Safety
Comparison of Image Quality Between Conventional and Low-Dose Nonenhanced Head CT
Mark E. Mullinsa, et al.
AJNR April 2004.
Reduction of mAs from 170 to 90

51. Radiation Safety What does all this mean?
1 CXR approximates the same risk as:
1 year watching TV (CRT)
1 coast to coast airplane flight
3 puffs on a cigarette
2 days living in Denver
1 Head CT is approximately 20 CXR
Health Physics Society on the web--

52. Radiation Safety The pregnant patient
Can another exam answer the question?
What is the gestational age?
Counsel the patient
3% of all deliveries have some type of spontaneous abnormality
The mother’s health is the primary concern.

53. Radiation Safety
"No single diagnostic procedure results in a radiation dose that threatens the well-being of the developing embryo and fetus." -- American College of Radiology
"Women should be counseled that x-ray exposure from a single diagnostic procedure does not result in harmful fetal effects. Specifically, exposure to less than 5 rad has not been associated with an increase in fetal anomalies or pregnancy loss." -- American College of Obstetricians and Gynecologists

54. Conclusion CT Terminology CT has risks
Attenuation (density) in Hounsfield units
Digital interpretation is standard of care
CT has risks
Contrast
Radiation exposure

55. CT Basics Neuroradiology The BASICS of CT CT History Protocol
Terminology
Contrast
Radiation Safety
Cases

56. Normal CT

57. 1 day year years

58. Normal CT Older person

59. Normal Enhanced CT

60. Case 1
55 yo female with sudden onset of worst headache of life

61. Case 1

62. Case 1

63. Case 1
What do I do now?

64. CTA

65. Normal Angiography

66. Diagnostic Angiography

67. Case 1 Subarachnoid Hemorrhage Most common cause is trauma Aneurysm
Vascular malformation
Tumor
Meningitis
Generally a younger age group

68. Case 2
82 yo male with mental status change after a fall

69. Case 2

70. Case 2 Subdural hematoma Venous bleeding from bridging veins
General presentation
Older age group
Mental status change after fall
50% have no trauma history

71. Subdural Hematoma

72. Case 3
44 yo female with right sided weakness and inability to speak

73. Case 3

74. Case 3
Acute ischemic left MCA stroke

75. MCA Stroke “Dense MCA”

76. Case 4 50 yo male post head trauma.
Pt was initially conscious but now 3 hours post trauma has had a sudden decrease in his neurological function.

77. Case 4

78. Case 4 Epidural hematoma
Typical history is a patient with head trauma who has a period of lucidity after trauma but then deteriorates rapidly.
Hemorrhage is a result of a tear through a meningeal artery.

79. Case 5
71 yo male who initially complained of incoordination of his left hand and subsequently collapsed

80. Case 5

81. Case 5 Intraparenchymal hemorrhage Hypertensive Amyloid angiopathy
Tumor
Trauma

82. Case 6 62 yo female acute onset headache
Hemiplegic on the right and unable to speak

83. Case 6
Add htn image here

84. Case 6 Hypertensive hemorrhage
Clinically looks like a large MCA stroke
Generally younger than amyloid angiopathy patients

85. Chronic Ischemic change = Encephalomalacia

86. Thrombolysis: Intravenous Intra-arterial
3 hours
Intra-arterial
6 hours ICA territory
24 hours basilar territory
CT head plain shows no established stroke nor hemorrhage
CT perfusion shows a salvagable penumbra

87. Case 7
53 y.o. male
Sudden onset of ataxia loss of consciousness proceeding rapidly to coma

89. Case 7
Probable basilar occlusion with cerebellar and brainstem infarction

90. Case 8
52 yo male with right sided weakness

91. Case 8

92. Case 8

93. Case 8 Acute lacunar infarction
Cannot reliably differentiate this finding on CT from remote lacune without clinical correlation.
MRI with diffusion is the GOLD STANDARD
A word on TIA

94. Chronic Small Vessel Disease

95. Case 9
59 yo female with multiple falls over last weekend

96. Case 9

97. Case 9
Stroke involving caudate head, anterior limb internal capsule and anterior putamen.
What is the artery?
Recurrent artery of Heubner

98. Case 10
42 yo male found in coma

99. Case 10

100. Case 10
Global ischemia

101. Angiographic Brain Death

102. Thank you