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Neuroradiology Dr. Grant J. Linnell Fellow Montreal Neurological Hospital McGill University
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
CT Basics <ul><li>No disclosures </li></ul>
Neuroradiologist <ul><li>A  consultant  in imaging and disease of the brain, spinal cord, head, neck, face and peripheral ...
Neuroradiology <ul><li>Plain Film </li></ul><ul><li>CT </li></ul><ul><li>US </li></ul><ul><li>MRI </li></ul><ul><li>Interv...
Neuroradiology <ul><li>A request for an exam is a consultation </li></ul><ul><ul><li>History </li></ul></ul><ul><ul><li>Pe...
CT Basics <ul><li>Computed tomography (CT) </li></ul><ul><li>Computed axial tomography or computer –assisted tomography (C...
CT Basics
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
CT History <ul><li>Electro-Musical Instruments </li></ul>
CT History SIR GODFREY N. HOUNSFIELD   <ul><li>1979 Nobel Laureate in Medicine   </li></ul>
CT History <ul><li>1972 – First clinical CT scanner </li></ul><ul><ul><li>Used for head examinations </li></ul></ul><ul><u...
CT History <ul><li>2004 – 64 slice scanner </li></ul><ul><ul><li>1024 x 1024 matrix </li></ul></ul><ul><ul><li>0.33s per r...
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
CT Protocolling <ul><li>What happens when an exam is requested? </li></ul><ul><ul><li>A requisiton is completed. </li></ul...
CT Protocolling <ul><li>CT head protocols </li></ul><ul><ul><li>With or Without contrast </li></ul></ul><ul><ul><li>CT Bra...
CT Protocolling <ul><li>Variables </li></ul><ul><ul><li>Plain or contrast enhanced </li></ul></ul><ul><ul><li>Slice positi...
CT Protocolling <ul><li>Patient Information </li></ul><ul><ul><li>Is the patient pregnant? </li></ul></ul><ul><ul><ul><li>...
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
CT Terminology <ul><li>Exams using  Ionizing radiation   </li></ul><ul><ul><li>Plain film </li></ul></ul><ul><ul><li>CT </...
CT Terminology <ul><li>Attenuation </li></ul><ul><ul><li>Hyperattenuating (hyperdense) </li></ul></ul><ul><ul><li>Hypoatte...
CT Terminology <ul><li>What we can see </li></ul><ul><ul><li>The brain is grey </li></ul></ul><ul><ul><ul><li>White matter...
CT Terminology <ul><li>Voxel </li></ul><ul><ul><li>Volume element </li></ul></ul><ul><ul><ul><li>A voxel is the 2 dimensio...
CT Terminology
CT Terminology <ul><li>Window Width </li></ul><ul><ul><li>Number of Hounsfield units from black to white </li></ul></ul><u...
CT Terminology
CT Artifacts
CT Terminology <ul><li>Digital reading stations are the standard of care in interpretation of CT and MRI. </li></ul><ul><l...
CT Terminology <ul><li>DICOM </li></ul><ul><ul><li>Digital Imaging and Communications in Medicin e </li></ul></ul><ul><ul>...
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
Contrast <ul><li>Barium </li></ul><ul><li>Iodinated  </li></ul><ul><ul><li>vascular </li></ul></ul><ul><ul><li>Biliary, Ur...
Contrast
Contrast <ul><li>Types of iodinated contrast </li></ul><ul><ul><li>Ionic  </li></ul></ul><ul><ul><li>Nonionic - standard o...
Contrast <ul><li>What are the risks of iodinated contrast? </li></ul><ul><ul><li>Contrast reaction </li></ul></ul><ul><ul>...
Contrast <ul><li>Who is at risk for an anaphylactic reaction? </li></ul><ul><ul><li>Patients with a prior history of contr...
Contrast <ul><li>Pretreatment for anaphylaxis </li></ul><ul><ul><li>50 mg Oral Prednisone 13, 7 and 1 hour prior to exam <...
Contrast <ul><li>What are the risk factors for contrast induced acute renal failure? </li></ul><ul><ul><li>Pre-existing re...
Contrast <ul><li>Considerations in patients with renal insufficiency </li></ul><ul><ul><li>Is the exam necessary? </li></u...
Contrast <ul><li>Pretreatment for renal insufficiency </li></ul><ul><ul><li>Hydration </li></ul></ul><ul><ul><li>Mucomyst ...
Contrast <ul><li>Contrast induced renal failure </li></ul><ul><ul><li>Elevated creatinine 24-48 hours after contrast which...
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
Radiation Safety <ul><li>Diagnostic CT Scans: Assessment of Patient, Physician, and Radiologist Awareness of Radiation Dos...
Radiation Safety <ul><li>Deterministic Effects </li></ul><ul><ul><li>Have a threshold below which no effect will be seen. ...
Radiation Safety <ul><li>Terminology </li></ul><ul><ul><li>Gy = Gray is the absorbed dose (SI unit) </li></ul></ul><ul><ul...
Radiation Safety <ul><li>Relative values of CT exam exposure </li></ul><ul><ul><li>Background radiation is 3 mSv/year </li...
Radiation Safety <ul><li>Effects  of X rays. </li></ul><ul><ul><li>Absorption of photons by biological material leads to b...
Radiation Safety <ul><li>Tissue/Organ radiosensitivity </li></ul><ul><ul><li>Fetal cells </li></ul></ul><ul><ul><li>Lympho...
Radiation Safety <ul><li>Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT  </li></ul><ul><ul><li>David ...
Radiation Safety <ul><li>3094 men received radiation for hemangioma </li></ul><ul><ul><li>Those receiving >100 mGy </li></...
Radiation Safety <ul><li>Hiroshima and Nagasaki </li></ul><ul><ul><li>T here  has been  no detectable  increase in genetic...
Radiation Safety <ul><li>Hiroshima and Nagasaki </li></ul><ul><ul><li>However, e xposed individuals who survived the acute...
Radiation Safety <ul><li>Hiroshima and Nagasaki </li></ul><ul><ul><li>Most victims with high doses died </li></ul></ul><ul...
Radiation Safety Comparison of Image Quality Between Conventional and Low-Dose Nonenhanced Head CT  Mark E. Mullins a ,  e...
Radiation Safety <ul><li>What does all this mean? </li></ul><ul><ul><li>1 CXR approximates the same risk as: </li></ul></u...
Radiation Safety <ul><li>The pregnant patient </li></ul><ul><ul><li>Can another exam answer the question? </li></ul></ul><...
Radiation Safety <ul><li>&quot;No single diagnostic procedure results in a radiation dose that threatens the well-being of...
Conclusion <ul><li>Neuroradiologists are consultants </li></ul><ul><li>Garbage in ------- Garbage out </li></ul><ul><li>CT...
CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The  BASICS  of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul>...
Normal  CT
1 day      1 year     2 years
Normal CT Older person
Normal Enhanced CT
Case 1 <ul><li>55 yo female with sudden onset of worst headache of life </li></ul>
Case 1
Case 1
Case 1 <ul><li>What do I do now? </li></ul>
CTA
Normal Angiography
Diagnostic Angiography
Case 1 <ul><li>Subarachnoid Hemorrhage </li></ul><ul><ul><li>Most common cause is trauma </li></ul></ul><ul><ul><li>Aneury...
Case 2 <ul><li>82 yo male with mental status change after a fall </li></ul>
Case 2
Case 2 <ul><li>Subdural hematoma </li></ul><ul><li>Venous bleeding from bridging veins </li></ul><ul><li>General presentat...
Subdural Hematoma
Case 3  <ul><li>44 yo female with right sided weakness and inability to speak </li></ul>
Case 3
Case 3 <ul><li>Acute ischemic left MCA stroke </li></ul>
MCA Stroke “Dense MCA”
Case 4 <ul><li>50 yo male post head trauma. </li></ul><ul><li>Pt was initially conscious but now 3 hours post trauma has h...
Case 4
Case 4 <ul><li>Epidural hematoma </li></ul><ul><ul><li>Typical history is a patient with head trauma who has a period of l...
Case 5 <ul><li>71 yo male who initially complained of incoordination of his left hand and subsequently collapsed </li></ul>
Case 5
Case 5 <ul><li>Intraparenchymal hemorrhage </li></ul><ul><ul><li>Hypertensive </li></ul></ul><ul><ul><li>Amyloid angiopath...
Case 6 <ul><li>62 yo female acute onset headache </li></ul><ul><ul><li>Hemiplegic on the right and unable to speak </li></...
Case 6 <ul><li>Add htn image here  </li></ul>
Case 6 <ul><li>Hypertensive hemorrhage </li></ul><ul><ul><li>Clinically looks like a large MCA stroke </li></ul></ul><ul><...
Chronic Ischemic change = Encephalomalacia
Thrombolysis: <ul><li>Intravenous </li></ul><ul><ul><li>3 hours </li></ul></ul><ul><li>Intra-arterial  </li></ul><ul><ul><...
Case 7 <ul><li>53 y.o. male </li></ul><ul><li>Sudden onset of ataxia loss of consciousness proceeding rapidly to coma </li...
 
Case 7 <ul><li>Probable basilar occlusion with cerebellar and brainstem infarction </li></ul>
Case 8 <ul><li>52 yo male with right sided weakness </li></ul>
Case 8
Case 8
Case 8 <ul><li>Acute lacunar infarction </li></ul><ul><ul><li>Cannot reliably differentiate this finding on CT from remote...
Chronic Small Vessel Disease
Case 9 <ul><li>59 yo female with multiple falls over last weekend </li></ul>
Case 9
Case 9 <ul><li>Stroke involving caudate head, anterior limb internal capsule and anterior putamen. </li></ul><ul><li>What ...
Case 10 <ul><li>42 yo male found in coma </li></ul>
Case 10
Case 10 <ul><li>Global ischemia </li></ul>
Angiographic Brain Death
Case 11 <ul><li>24 yo male with siezures </li></ul>
Case 11
Case 11 <ul><li>Heterotopia </li></ul>
Case 12 <ul><li>34 y.o. female </li></ul><ul><li>Severe H/A,nausea </li></ul><ul><li>Taking oral contraceptives </li></ul>
Case 12
Case 12
Case 12  <ul><li>Transverse sinus thrombosis </li></ul>
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Transcript of "Ct basics 2"

  1. 1. Neuroradiology Dr. Grant J. Linnell Fellow Montreal Neurological Hospital McGill University
  2. 2. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  3. 3. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  4. 4. CT Basics <ul><li>No disclosures </li></ul>
  5. 5. Neuroradiologist <ul><li>A consultant in imaging and disease of the brain, spinal cord, head, neck, face and peripheral nerves </li></ul>
  6. 6. Neuroradiology <ul><li>Plain Film </li></ul><ul><li>CT </li></ul><ul><li>US </li></ul><ul><li>MRI </li></ul><ul><li>Interventional </li></ul><ul><ul><li>Angiography </li></ul></ul><ul><ul><li>Myelography </li></ul></ul><ul><ul><li>Biopsy </li></ul></ul><ul><li>Nuclear Medicine </li></ul>
  7. 7. Neuroradiology <ul><li>A request for an exam is a consultation </li></ul><ul><ul><li>History </li></ul></ul><ul><ul><li>Pertinent physical exam findings </li></ul></ul><ul><ul><ul><li>Lab results </li></ul></ul></ul><ul><ul><ul><ul><li>Creatinine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>PT/INR </li></ul></ul></ul></ul><ul><ul><li>What is the question? </li></ul></ul>
  8. 8. CT Basics <ul><li>Computed tomography (CT) </li></ul><ul><li>Computed axial tomography or computer –assisted tomography (CAT) </li></ul>
  9. 9. CT Basics
  10. 10. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  11. 11. CT History <ul><li>Electro-Musical Instruments </li></ul>
  12. 12. CT History SIR GODFREY N. HOUNSFIELD <ul><li>1979 Nobel Laureate in Medicine </li></ul>
  13. 13. CT History <ul><li>1972 – First clinical CT scanner </li></ul><ul><ul><li>Used for head examinations </li></ul></ul><ul><ul><li>Water bath required </li></ul></ul><ul><ul><li>80 x 80 matrix </li></ul></ul><ul><ul><li>4 minutes per revolution </li></ul></ul><ul><ul><li>1 image per revolution </li></ul></ul><ul><ul><li>8 levels of grey </li></ul></ul><ul><ul><li>Overnight image reconstruction </li></ul></ul>
  14. 14. CT History <ul><li>2004 – 64 slice scanner </li></ul><ul><ul><li>1024 x 1024 matrix </li></ul></ul><ul><ul><li>0.33s per revolution </li></ul></ul><ul><ul><li>64 images per revolution </li></ul></ul><ul><ul><li>0.4mm slice thickness </li></ul></ul><ul><ul><li>20 images reconstructed/second </li></ul></ul>
  15. 15. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  16. 16. CT Protocolling <ul><li>What happens when an exam is requested? </li></ul><ul><ul><li>A requisiton is completed. </li></ul></ul><ul><ul><li>The requested exam is protocolled according to history, physical exam and previous exams. </li></ul></ul><ul><ul><li>The patient information is confirmed. </li></ul></ul><ul><ul><li>The exam is then performed. </li></ul></ul><ul><ul><li>Images are ready to be interpreted in … </li></ul></ul><ul><ul><ul><li>Uncomplicated exam – 5-10 minutes after completion </li></ul></ul></ul><ul><ul><ul><li>Complicated exams with reconstructions take at least 1 hour but usually 1-2 hours. </li></ul></ul></ul>
  17. 17. CT Protocolling <ul><li>CT head protocols </li></ul><ul><ul><li>With or Without contrast </li></ul></ul><ul><ul><li>CT Brain </li></ul></ul><ul><ul><li>CT Brain with posterior fossa images </li></ul></ul><ul><ul><li>CT Angiogram/Venogram </li></ul></ul><ul><ul><li>CT Perfusion </li></ul></ul><ul><ul><li>CT of Sinuses </li></ul></ul><ul><ul><li>CT of Orbit </li></ul></ul><ul><ul><li>CT of Temporal bones </li></ul></ul><ul><ul><li>CT of Mastoid bones </li></ul></ul><ul><ul><li>CT of Skull </li></ul></ul><ul><ul><li>CT of Face </li></ul></ul>
  18. 18. CT Protocolling <ul><li>Variables </li></ul><ul><ul><li>Plain or contrast enhanced </li></ul></ul><ul><ul><li>Slice positioning </li></ul></ul><ul><ul><li>Slice thickness </li></ul></ul><ul><ul><li>Slice orientation </li></ul></ul><ul><ul><li>Slice spacing and overlap </li></ul></ul><ul><ul><li>Timing of imaging and contrast administration </li></ul></ul><ul><ul><li>Reconstruction algorhithm </li></ul></ul><ul><ul><li>Radiation dosimetry </li></ul></ul>
  19. 19. CT Protocolling <ul><li>Patient Information </li></ul><ul><ul><li>Is the patient pregnant? </li></ul></ul><ul><ul><ul><li>Radiation safety </li></ul></ul></ul><ul><ul><li>Can the patient cooperate for the exam? </li></ul></ul>
  20. 20. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases (Stroke) </li></ul></ul>
  21. 21. CT Terminology <ul><li>Exams using Ionizing radiation </li></ul><ul><ul><li>Plain film </li></ul></ul><ul><ul><li>CT </li></ul></ul><ul><ul><ul><li>1/10 of all exams </li></ul></ul></ul><ul><ul><ul><li>2/3 OF RADIATION EXPOSURE </li></ul></ul></ul><ul><ul><li>Fluoroscopy </li></ul></ul><ul><ul><ul><li>Angiography, barium studies </li></ul></ul></ul><ul><ul><li>Nuclear medicine </li></ul></ul><ul><ul><ul><li>V/Q scan, bone scan </li></ul></ul></ul>
  22. 22. CT Terminology <ul><li>Attenuation </li></ul><ul><ul><li>Hyperattenuating (hyperdense) </li></ul></ul><ul><ul><li>Hypoattenuating (hypodense) </li></ul></ul><ul><ul><li>Isoattenuating (isodense) </li></ul></ul><ul><li>Attenuation is measured in Hounsfield units </li></ul><ul><ul><li>Scale -1000 to 1000 </li></ul></ul><ul><ul><ul><li>-1000 is air </li></ul></ul></ul><ul><ul><ul><li>0 is water </li></ul></ul></ul><ul><ul><ul><li>1000 is cortical bone </li></ul></ul></ul>
  23. 23. CT Terminology <ul><li>What we can see </li></ul><ul><ul><li>The brain is grey </li></ul></ul><ul><ul><ul><li>White matter is usually dark grey (40) </li></ul></ul></ul><ul><ul><ul><li>Grey matter is usually light grey (45) </li></ul></ul></ul><ul><ul><ul><li>CSF is black (0) </li></ul></ul></ul><ul><ul><ul><li>Things that are brite on CT </li></ul></ul></ul><ul><ul><ul><ul><li>Bone or calcification (>300) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Contrast </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Hemorrhage (Acute ~ 70) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Hypercellular masses </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Metallic foreign bodies </li></ul></ul></ul></ul>
  24. 24. CT Terminology <ul><li>Voxel </li></ul><ul><ul><li>Volume element </li></ul></ul><ul><ul><ul><li>A voxel is the 2 dimensional representation of a 3 dimensional pixel (picture element). </li></ul></ul></ul><ul><ul><li>Partial volume averaging </li></ul></ul>
  25. 25. CT Terminology
  26. 26. CT Terminology <ul><li>Window Width </li></ul><ul><ul><li>Number of Hounsfield units from black to white </li></ul></ul><ul><li>Level or Center </li></ul><ul><ul><li>Hounsfield unit approximating mid-gray </li></ul></ul>
  27. 27. CT Terminology
  28. 28. CT Artifacts
  29. 29. CT Terminology <ul><li>Digital reading stations are the standard of care in interpretation of CT and MRI. </li></ul><ul><li>Why? </li></ul><ul><ul><li>Volume of images </li></ul></ul><ul><ul><li>Ability to manipulate and reconstruct images </li></ul></ul><ul><ul><li>Cost </li></ul></ul>
  30. 30. CT Terminology <ul><li>DICOM </li></ul><ul><ul><li>Digital Imaging and Communications in Medicin e </li></ul></ul><ul><ul><li>DICOM provides standardized formats for images, a common information model, application service definitions, and protocols for communication. </li></ul></ul>
  31. 31. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  32. 32. Contrast <ul><li>Barium </li></ul><ul><li>Iodinated </li></ul><ul><ul><li>vascular </li></ul></ul><ul><ul><li>Biliary, Urinary </li></ul></ul><ul><ul><li>CSF </li></ul></ul><ul><li>Gadolinium </li></ul>
  33. 33. Contrast
  34. 34. Contrast <ul><li>Types of iodinated contrast </li></ul><ul><ul><li>Ionic </li></ul></ul><ul><ul><li>Nonionic - standard of care </li></ul></ul><ul><ul><ul><li>No change in death rate from reaction but number of reactions is decreased by factor of 4. </li></ul></ul></ul><ul><li>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. </li></ul>
  35. 35. Contrast <ul><li>What are the risks of iodinated contrast? </li></ul><ul><ul><li>Contrast reaction </li></ul></ul><ul><ul><ul><li>1 in 10,000 have true anaphylactic reaction </li></ul></ul></ul><ul><ul><ul><li>1 in 100,000 to 1 in 1,000,000 will die </li></ul></ul></ul><ul><ul><li>Medical Issues </li></ul></ul><ul><ul><ul><li>Acute renal failure </li></ul></ul></ul><ul><ul><ul><li>Lactic acidosis in diabetics </li></ul></ul></ul><ul><ul><ul><ul><ul><li>If on Glucophage, patient must stop Glucophage for 48 hours after exam to prevent serious lactic acidosis </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Cardiac </li></ul></ul></ul><ul><ul><li>Extravasation </li></ul></ul>
  36. 36. Contrast <ul><li>Who is at risk for an anaphylactic reaction? </li></ul><ul><ul><li>Patients with a prior history of contrast reaction </li></ul></ul><ul><ul><li>Patients with a history asthma react at a rate of 1 in 2,000 </li></ul></ul><ul><ul><li>Patients with multiple environmental allergies, ie foods, hay fever, medications </li></ul></ul>Amin MM, et al. Ionic and nonionic contrast media: Current status and controversies. Appl Radiol 1993; 22: 41-54.
  37. 37. Contrast <ul><li>Pretreatment for anaphylaxis </li></ul><ul><ul><li>50 mg Oral Prednisone 13, 7 and 1 hour prior to exam </li></ul></ul><ul><ul><li>50 mg oral Benedryl 1 hour prior to exam </li></ul></ul><ul><ul><li>In emergency, 200 mg iv hydrocortisone 2-4 hours prior to exam </li></ul></ul>
  38. 38. Contrast <ul><li>What are the risk factors for contrast induced acute renal failure? </li></ul><ul><ul><li>Pre-existing renal insufficiency </li></ul></ul><ul><ul><li>Contrast volume </li></ul></ul><ul><ul><li>Dehydration </li></ul></ul><ul><ul><li>Advanced age </li></ul></ul><ul><ul><li>Drugs </li></ul></ul><ul><ul><li>Multiple myeloma </li></ul></ul><ul><ul><li>Cardiac failure </li></ul></ul>
  39. 39. Contrast <ul><li>Considerations in patients with renal insufficiency </li></ul><ul><ul><li>Is the exam necessary? </li></ul></ul><ul><ul><li>Is there an alternative exam that can answer the question? </li></ul></ul><ul><ul><li>Decrease contrast dose </li></ul></ul>
  40. 40. Contrast <ul><li>Pretreatment for renal insufficiency </li></ul><ul><ul><li>Hydration </li></ul></ul><ul><ul><li>Mucomyst </li></ul></ul><ul><ul><ul><li>600 mg po BID the day before and day of study </li></ul></ul></ul>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
  41. 41. Contrast <ul><li>Contrast induced renal failure </li></ul><ul><ul><li>Elevated creatinine 24-48 hours after contrast which resolves over 7-21 days. </li></ul></ul><ul><ul><li>Can require dialysis </li></ul></ul>Mehran, R. et al. Radiocontrast induced renal failure:Allocations and outcomes. Reviews in Cardiovascular Medicine Vol. 2 Supp. 1 2001
  42. 42. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  43. 43. Radiation Safety <ul><li>Diagnostic CT Scans: Assessment of Patient, Physician, and Radiologist Awareness of Radiation Dose and Possible Risks </li></ul><ul><ul><li>Lee, C. et al. Radiology 2004;231:393 </li></ul></ul>
  44. 44. Radiation Safety <ul><li>Deterministic Effects </li></ul><ul><ul><li>Have a threshold below which no effect will be seen. </li></ul></ul><ul><li>Stochastic Effects </li></ul><ul><ul><li>Have no threshold and the effects are based on the dose x quality factor. </li></ul></ul>
  45. 45. Radiation Safety <ul><li>Terminology </li></ul><ul><ul><li>Gy = Gray is the absorbed dose (SI unit) </li></ul></ul><ul><ul><ul><li>The equivalent of 1 joule/kg of tissue </li></ul></ul></ul><ul><ul><ul><li>Rad = radiation absorbed dose </li></ul></ul></ul><ul><ul><li>Sv = Sievert is the dose equivalent (SI unit) </li></ul></ul><ul><ul><ul><li>Absorbed dose multiplied by a quality factor </li></ul></ul></ul><ul><ul><ul><li>Rem = radiation equivalent man </li></ul></ul></ul>
  46. 46. Radiation Safety <ul><li>Relative values of CT exam exposure </li></ul><ul><ul><li>Background radiation is 3 mSv/year </li></ul></ul><ul><ul><ul><li>Water, food, air, solar </li></ul></ul></ul><ul><ul><ul><li>In Denver (altitude 5280 ft.) 10 mSv/year </li></ul></ul></ul><ul><ul><li>CXR = 0.1 mSv </li></ul></ul><ul><ul><li>CT head = 2 mSv </li></ul></ul><ul><ul><li>CT Chest = 8 mSv </li></ul></ul><ul><ul><li>CT Abdomen and Pelvis = 20 mSv </li></ul></ul>-The equivalent of 200 CXR
  47. 47. Radiation Safety <ul><li>Effects of X rays. </li></ul><ul><ul><li>Absorption of photons by biological material leads to breakage of chemical bonds. </li></ul></ul><ul><ul><li>The principal biological effect results from damage to DNA caused by either the direct or indirect action of radiation. </li></ul></ul>
  48. 48. Radiation Safety <ul><li>Tissue/Organ radiosensitivity </li></ul><ul><ul><li>Fetal cells </li></ul></ul><ul><ul><li>Lymphoid and hematopoietic tissues; intestinal epithelium </li></ul></ul><ul><ul><li>Epidermal, esophageal, oropharyngeal epithelia </li></ul></ul><ul><ul><li>Interstitial connective tissue, fine vasculature </li></ul></ul><ul><ul><li>Renal, hepatic, and pancreatic tissue </li></ul></ul><ul><ul><li>Muscle and neuronal tissue </li></ul></ul>
  49. 49. Radiation Safety <ul><li>Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT </li></ul><ul><ul><li>David J. Brenne r, et al. AJR 2001; 176:289-296 </li></ul></ul><ul><ul><ul><li>Additional 170 cancer deaths for each year of head CT in the US. </li></ul></ul></ul><ul><ul><ul><ul><li>140,000 total cancer deaths, therefore ~ 0.12% increase </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1 in 1500 will die from radiologically induced cancer </li></ul></ul></ul></ul>
  50. 50. Radiation Safety <ul><li>3094 men received radiation for hemangioma </li></ul><ul><ul><li>Those receiving >100 mGy </li></ul></ul><ul><ul><li>Decreased high school attendance </li></ul></ul><ul><ul><li>Lower cognitive test scores </li></ul></ul>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: 19 - 0.
  51. 51. Radiation Safety <ul><li>Hiroshima and Nagasaki </li></ul><ul><ul><li>T here 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. </li></ul></ul>William J Schull, Effects of Atomic Radiation: A Half-Century of Studies from Hiroshima and Nagasaki , 1995.
  52. 52. Radiation Safety <ul><li>Hiroshima and Nagasaki </li></ul><ul><ul><li>However, e xposed individuals who survived the acute effects were later found to suffer increased incidence of cancer of essentially all organs. </li></ul></ul>William J Schull, Effects of Atomic Radiation: A Half-Century of Studies from Hiroshima and Nagasaki , 1995.
  53. 53. Radiation Safety <ul><li>Hiroshima and Nagasaki </li></ul><ul><ul><li>Most victims with high doses died </li></ul></ul><ul><ul><li>Victims with low doses despite their large numbers are still statistically insignificant. </li></ul></ul>
  54. 54. Radiation Safety Comparison of Image Quality Between Conventional and Low-Dose Nonenhanced Head CT Mark E. Mullins a , et al. AJNR April 2004. Reduction of mAs from 170 to 90
  55. 55. Radiation Safety <ul><li>What does all this mean? </li></ul><ul><ul><li>1 CXR approximates the same risk as: </li></ul></ul><ul><ul><ul><li>1 year watching TV (CRT) </li></ul></ul></ul><ul><ul><ul><li>1 coast to coast airplane flight </li></ul></ul></ul><ul><ul><ul><li>3 puffs on a cigarette </li></ul></ul></ul><ul><ul><ul><li>2 days living in Denver </li></ul></ul></ul><ul><ul><li>1 Head CT is approximately 20 CXR </li></ul></ul>Health Physics Society on the web--http://hps.org
  56. 56. Radiation Safety <ul><li>The pregnant patient </li></ul><ul><ul><li>Can another exam answer the question? </li></ul></ul><ul><ul><li>W hat is the gestational age? </li></ul></ul><ul><ul><li>Counsel the patient </li></ul></ul><ul><ul><ul><li>3% of all deliveries have some type of spontaneous abnormality </li></ul></ul></ul><ul><li>The mother’s health is the primary concern. </li></ul>
  57. 57. Radiation Safety <ul><li>&quot;No single diagnostic procedure results in a radiation dose that threatens the well-being of the developing embryo and fetus.&quot; -- American College of Radiology </li></ul><ul><li>&quot;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.&quot; -- American College of Obstetricians and Gynecologists </li></ul>
  58. 58. Conclusion <ul><li>Neuroradiologists are consultants </li></ul><ul><li>Garbage in ------- Garbage out </li></ul><ul><li>CT Terminology </li></ul><ul><ul><li>Attenuation (density) in Hounsfield units </li></ul></ul><ul><ul><li>Digital interpretation is standard of care </li></ul></ul><ul><li>CT has risks </li></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation exposure </li></ul></ul>
  59. 59. CT Basics <ul><li>Neuroradiology </li></ul><ul><li>The BASICS of CT </li></ul><ul><ul><li>CT History </li></ul></ul><ul><ul><li>Protocol </li></ul></ul><ul><ul><li>Terminology </li></ul></ul><ul><ul><li>Contrast </li></ul></ul><ul><ul><li>Radiation Safety </li></ul></ul><ul><ul><li>Cases </li></ul></ul>
  60. 60. Normal CT
  61. 61. 1 day 1 year 2 years
  62. 62. Normal CT Older person
  63. 63. Normal Enhanced CT
  64. 64. Case 1 <ul><li>55 yo female with sudden onset of worst headache of life </li></ul>
  65. 65. Case 1
  66. 66. Case 1
  67. 67. Case 1 <ul><li>What do I do now? </li></ul>
  68. 68. CTA
  69. 69. Normal Angiography
  70. 70. Diagnostic Angiography
  71. 71. Case 1 <ul><li>Subarachnoid Hemorrhage </li></ul><ul><ul><li>Most common cause is trauma </li></ul></ul><ul><ul><li>Aneurysm </li></ul></ul><ul><ul><li>Vascular malformation </li></ul></ul><ul><ul><li>Tumor </li></ul></ul><ul><ul><li>Meningitis </li></ul></ul><ul><ul><li>Generally a younger age group </li></ul></ul>
  72. 72. Case 2 <ul><li>82 yo male with mental status change after a fall </li></ul>
  73. 73. Case 2
  74. 74. Case 2 <ul><li>Subdural hematoma </li></ul><ul><li>Venous bleeding from bridging veins </li></ul><ul><li>General presentation </li></ul><ul><ul><li>Older age group </li></ul></ul><ul><ul><li>Mental status change after fall </li></ul></ul><ul><ul><li>50% have no trauma history </li></ul></ul>
  75. 75. Subdural Hematoma
  76. 76. Case 3 <ul><li>44 yo female with right sided weakness and inability to speak </li></ul>
  77. 77. Case 3
  78. 78. Case 3 <ul><li>Acute ischemic left MCA stroke </li></ul>
  79. 79. MCA Stroke “Dense MCA”
  80. 80. Case 4 <ul><li>50 yo male post head trauma. </li></ul><ul><li>Pt was initially conscious but now 3 hours post trauma has had a sudden decrease in his neurological function. </li></ul>
  81. 81. Case 4
  82. 82. Case 4 <ul><li>Epidural hematoma </li></ul><ul><ul><li>Typical history is a patient with head trauma who has a period of lucidity after trauma but then deteriorates rapidly. </li></ul></ul><ul><ul><li>Hemorrhage is a result of a tear through a meningeal artery. </li></ul></ul>
  83. 83. Case 5 <ul><li>71 yo male who initially complained of incoordination of his left hand and subsequently collapsed </li></ul>
  84. 84. Case 5
  85. 85. Case 5 <ul><li>Intraparenchymal hemorrhage </li></ul><ul><ul><li>Hypertensive </li></ul></ul><ul><ul><li>Amyloid angiopathy </li></ul></ul><ul><ul><li>Tumor </li></ul></ul><ul><ul><li>Trauma </li></ul></ul>
  86. 86. Case 6 <ul><li>62 yo female acute onset headache </li></ul><ul><ul><li>Hemiplegic on the right and unable to speak </li></ul></ul>
  87. 87. Case 6 <ul><li>Add htn image here </li></ul>
  88. 88. Case 6 <ul><li>Hypertensive hemorrhage </li></ul><ul><ul><li>Clinically looks like a large MCA stroke </li></ul></ul><ul><ul><li>Generally younger than amyloid angiopathy patients </li></ul></ul>
  89. 89. Chronic Ischemic change = Encephalomalacia
  90. 90. Thrombolysis: <ul><li>Intravenous </li></ul><ul><ul><li>3 hours </li></ul></ul><ul><li>Intra-arterial </li></ul><ul><ul><li>6 hours ICA territory </li></ul></ul><ul><ul><li>24 hours basilar territory </li></ul></ul><ul><li>CT head plain shows no established stroke nor hemorrhage </li></ul><ul><li>CT perfusion shows a salvagable penumbra </li></ul>
  91. 91. Case 7 <ul><li>53 y.o. male </li></ul><ul><li>Sudden onset of ataxia loss of consciousness proceeding rapidly to coma </li></ul>
  92. 93. Case 7 <ul><li>Probable basilar occlusion with cerebellar and brainstem infarction </li></ul>
  93. 94. Case 8 <ul><li>52 yo male with right sided weakness </li></ul>
  94. 95. Case 8
  95. 96. Case 8
  96. 97. Case 8 <ul><li>Acute lacunar infarction </li></ul><ul><ul><li>Cannot reliably differentiate this finding on CT from remote lacune without clinical correlation. </li></ul></ul><ul><ul><li>MRI with diffusion is the GOLD STANDARD </li></ul></ul><ul><ul><li>A word on TIA </li></ul></ul>
  97. 98. Chronic Small Vessel Disease
  98. 99. Case 9 <ul><li>59 yo female with multiple falls over last weekend </li></ul>
  99. 100. Case 9
  100. 101. Case 9 <ul><li>Stroke involving caudate head, anterior limb internal capsule and anterior putamen. </li></ul><ul><li>What is the artery? </li></ul><ul><li>Recurrent artery of Heubner </li></ul>
  101. 102. Case 10 <ul><li>42 yo male found in coma </li></ul>
  102. 103. Case 10
  103. 104. Case 10 <ul><li>Global ischemia </li></ul>
  104. 105. Angiographic Brain Death
  105. 106. Case 11 <ul><li>24 yo male with siezures </li></ul>
  106. 107. Case 11
  107. 108. Case 11 <ul><li>Heterotopia </li></ul>
  108. 109. Case 12 <ul><li>34 y.o. female </li></ul><ul><li>Severe H/A,nausea </li></ul><ul><li>Taking oral contraceptives </li></ul>
  109. 110. Case 12
  110. 111. Case 12
  111. 112. Case 12 <ul><li>Transverse sinus thrombosis </li></ul>
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