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Neuroradiology

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A consultant in imaging and disease of the brain, spinal cord, ... CT Brain with posterior fossa images. CT Angiogram/Venogram. CT Perfusion. CT of Sinuses ... – PowerPoint PPT presentation

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Title: Neuroradiology


1
Neuroradiology
  • Dr. Grant J. Linnell
  • Fellow
  • Montreal Neurological Hospital
  • McGill University

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
CT Basics
  • No disclosures

5
Neuroradiologist
  • A consultant in imaging and disease of the brain,
    spinal cord, head, neck, face and peripheral
    nerves

6
Neuroradiology
  • Plain Film
  • CT
  • US
  • MRI
  • Interventional
  • Angiography
  • Myelography
  • Biopsy
  • Nuclear Medicine

7
Neuroradiology
  • A request for an exam is a consultation
  • History
  • Pertinent physical exam findings
  • Lab results
  • Creatinine
  • PT/INR
  • What is the question?

8
CT Basics
  • Computed tomography (CT)
  • Computed axial tomography or computer assisted
    tomography (CAT)

9
CT Basics
10
CT Basics
  • Neuroradiology
  • The BASICS of CT
  • CT History
  • Protocol
  • Terminology
  • Contrast
  • Radiation Safety
  • Cases

11
CT History
  • Electro-Musical Instruments

12
CT HistorySIR GODFREY N. HOUNSFIELD
  • 1979 Nobel Laureate in Medicine

13
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

14
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

15
CT Basics
  • Neuroradiology
  • The BASICS of CT
  • CT History
  • Protocol
  • Terminology
  • Contrast
  • Radiation Safety
  • Cases

16
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.

17
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

18
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

19
CT Protocolling
  • Patient Information
  • Is the patient pregnant?
  • Radiation safety
  • Can the patient cooperate for the exam?

20
CT Basics
  • Neuroradiology
  • The BASICS of CT
  • CT History
  • Protocol
  • Terminology
  • Contrast
  • Radiation Safety
  • Cases (Stroke)

21
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

22
CT Terminology
  • Attenuation
  • Hyperattenuating (hyperdense)
  • Hypoattenuating (hypodense)
  • Isoattenuating (isodense)
  • Attenuation is measured in Hounsfield units
  • Scale -1000 to 1000
  • -1000 is air
  • 0 is water
  • 1000 is cortical bone

23
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 (gt300)
  • Contrast
  • Hemorrhage (Acute 70)
  • Hypercellular masses
  • Metallic foreign bodies

24
CT Terminology
  • Voxel
  • Volume element
  • A voxel is the 2 dimensional representation of a
    3 dimensional pixel (picture element).
  • Partial volume averaging

25
CT Terminology
26
CT Terminology
  • Window Width
  • Number of Hounsfield units from black to white
  • Level or Center
  • Hounsfield unit approximating mid-gray

27
CT Terminology
28
CT Artifacts
29
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

30
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.

31
CT Basics
  • Neuroradiology
  • The BASICS of CT
  • CT History
  • Protocol
  • Terminology
  • Contrast
  • Radiation Safety
  • Cases

32
Contrast
  • Barium
  • Iodinated
  • vascular
  • Biliary, Urinary
  • CSF
  • Gadolinium

33
Contrast
34
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.

35
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

36
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 41-54.
37
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

38
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

39
Contrast
  • Considerations in patients with renal
    insufficiency
  • Is the exam necessary?
  • Is there an alternative exam that can answer the
    question?
  • Decrease contrast dose

40
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 20343(3)180-4
41
Contrast
  • Contrast induced renal failure
  • Elevated creatinine 24-48 hours after contrast
    which resolves over 7-21 days.
  • Can require dialysis

Mehran, R. et al. Radiocontrast induced renal
failureAllocations and outcomes. Reviews in
Cardiovascular Medicine Vol. 2 Supp. 1 2001
42
CT Basics
  • Neuroradiology
  • The BASICS of CT
  • CT History
  • Protocol
  • Terminology
  • Contrast
  • Radiation Safety
  • Cases

43
Radiation Safety
  • Diagnostic CT Scans Assessment of Patient,
    Physician, and Radiologist Awareness of Radiation
    Dose and Possible Risks
  • Lee, C. et al. Radiology 2004231393

44
Radiation Safety
  • Deterministic 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.

45
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

46
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
47
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.

48
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

49
Radiation Safety
  • Estimated Risks of Radiation-Induced Fatal Cancer
    from Pediatric CT
  • David J. Brenner, et al. AJR 2001 176289-296
  • 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

50
Radiation Safety
  • 3094 men received radiation for hemangioma
  • Those receiving gt100 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
studyBMJ, Jan 2004 328 19 - 0.
51
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.
52
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.
53
Radiation Safety
  • Hiroshima and Nagasaki
  • Most victims with high doses died
  • Victims with low doses despite their large
    numbers are still statistically insignificant.

54
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
55
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--http//hps.org
56
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 mothers health is the primary concern.

57
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

58
Conclusion
  • Neuroradiologists are consultants
  • Garbage in ------- Garbage out
  • CT Terminology
  • Attenuation (density) in Hounsfield units
  • Digital interpretation is standard of care
  • CT has risks
  • Contrast
  • Radiation exposure

59
CT Basics
  • Neuroradiology
  • The BASICS of CT
  • CT History
  • Protocol
  • Terminology
  • Contrast
  • Radiation Safety
  • Cases

60
Normal CT
61
1 day 1 year 2 years
62
Normal CTOlder person
63
Normal Enhanced CT
64
Case 1
  • 55 yo female with sudden onset of worst headache
    of life

65
Case 1
66
Case 1
67
Case 1
  • What do I do now?

68
CTA
69
Normal Angiography
70
Diagnostic Angiography
71
Case 1
  • Subarachnoid Hemorrhage
  • Most common cause is trauma
  • Aneurysm
  • Vascular malformation
  • Tumor
  • Meningitis
  • Generally a younger age group

72
Case 2
  • 82 yo male with mental status change after a fall

73
Case 2
74
Case 2
  • Subdural hematoma
  • Venous bleeding from bridging veins
  • General presentation
  • Older age group
  • Mental status change after fall
  • 50 have no trauma history

75
Subdural Hematoma
76
Case 3
  • 44 yo female with right sided weakness and
    inability to speak

77
Case 3
78
Case 3
  • Acute ischemic left MCA stroke

79
MCA StrokeDense MCA
80
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.

81
Case 4
82
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.

83
Case 5
  • 71 yo male who initially complained of
    incoordination of his left hand and subsequently
    collapsed

84
Case 5
85
Case 5
  • Intraparenchymal hemorrhage
  • Hypertensive
  • Amyloid angiopathy
  • Tumor
  • Trauma

86
Case 6
  • 62 yo female acute onset headache
  • Hemiplegic on the right and unable to speak

87
Case 6
  • Add htn image here

88
Case 6
  • Hypertensive hemorrhage
  • Clinically looks like a large MCA stroke
  • Generally younger than amyloid angiopathy patients

89
Chronic Ischemic change Encephalomalacia
90
Thrombolysis
  • Intravenous
  • 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

91
Case 7
  • 53 y.o. male
  • Sudden onset of ataxia loss of consciousness
    proceeding rapidly to coma

92
(No Transcript)
93
Case 7
  • Probable basilar occlusion with cerebellar and
    brainstem infarction

94
Case 8
  • 52 yo male with right sided weakness

95
Case 8
96
Case 8
97
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

98
Chronic Small Vessel Disease
99
Case 9
  • 59 yo female with multiple falls over last weekend

100
Case 9
101
Case 9
  • Stroke involving caudate head, anterior limb
    internal capsule and anterior putamen.
  • What is the artery?
  • Recurrent artery of Heubner

102
Case 10
  • 42 yo male found in coma

103
Case 10
104
Case 10
  • Global ischemia

105
Angiographic Brain Death
106
Case 11
  • 24 yo male with siezures

107
Case 11
108
Case 11
  • Heterotopia

109
Case 12
  • 34 y.o. female
  • Severe H/A,nausea
  • Taking oral contraceptives

110
Case 12
111
Case 12
112
Case 12
  • Transverse sinus thrombosis
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