Sianny Suryawati Radiology Department, Faculty of Medicine Wijaya Kusuma University, Surabaya 2015.
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Transcript of Sianny Suryawati Radiology Department, Faculty of Medicine Wijaya Kusuma University, Surabaya 2015.
BASIC NEURORADIOLOGYSianny SuryawatiRadiology Department, Faculty of MedicineWijaya Kusuma University, Surabaya2015
Outline• Normal Imaging Anatomy of Brain • Basic Features of Brain Lesions• Brain Tumor• Cerebrovascular Disease• Traumatic Brain Injury
Normal Imaging Anatomy of Brain • Skull and Meninges (Dura, Pia)• Vasculature: Veins and Arteries• Surface Anatomy-Lobes, gyri, Sulci• Histologic-Broadman’s• Functional-motor, sensory, speech• White Matter• Cross sectional imaging
Anterior circulation Internal Carotid ArteriesPosterior Circulation Vertebral arteries
Superficial and Deep Arterial Supply to the Cerebral Hemispheres
Neuroradiology Modalities : • Plain Film • CT• US• MRI• Interventional • Angiography• Myelography• Biopsy • Nuclear Medicine
CT Basics
CT Basics• Neuroradiology• The BASICS of CT• CT History• Protocol• Terminology• Contrast• Radiation Safety• Cases
SIR GODFREY N. HOUNSFIELD
• 1979 Nobel Laureate in Medicine
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
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
CT Basics• Neuroradiology• The BASICS of CT• CT History• Protocol• Terminology• Contrast• Radiation Safety• Cases
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.
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
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
CT Protocolling• Patient Information• Is the patient pregnant?• Radiation safety
• Can the patient cooperate for the exam?
CT Basics• Neuroradiology• The BASICS of CT• CT History• Protocol• Terminology• Contrast• Radiation Safety• Cases (Stroke)
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
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
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
CT Terminology• Voxel• Volume element• A voxel is the 2 dimensional representation of a 3
dimensional pixel (picture element).• Partial volume averaging
CT Terminology
CT Terminology• Window Width• Number of Hounsfield units from black to white
• Level or Center• Hounsfield unit approximating mid-gray
CT Terminology
CT Artifacts
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
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.
CT Basics• Neuroradiology• The BASICS of CT• CT History• Protocol• Terminology• Contrast• Radiation Safety• Cases
Contrast• Barium• Iodinated • vascular• Biliary, Urinary• CSF
• Gadolinium
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.
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
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.
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
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
Contrast• Considerations in patients with renal insufficiency• Is the exam necessary?• Is there an alternative exam that can answer the
question?• Decrease contrast dose
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
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 failure:Allocations and outcomes.
Reviews in Cardiovascular Medicine Vol. 2 Supp. 1 2001
CT Basics• Neuroradiology• The BASICS of CT• CT History• Protocol• Terminology• Contrast• Radiation Safety• Cases
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
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.
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
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
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.
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
Radiation Safety
• Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT • David J. Brenner, et al. AJR 2001; 176:289-296• 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
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 studyBMJ, Jan 2004; 328: 19 - 0.
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.
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.
Radiation Safety• Hiroshima and Nagasaki• Most victims with high doses died• Victims with low doses despite their large numbers are
still statistically insignificant.
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
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
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.
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
Conclusion• CT Terminology• Attenuation (density) in Hounsfield units• Digital interpretation is standard of care
• CT has risks• Contrast• Radiation exposure
CT Basics• Neuroradiology• The BASICS of CT• CT History• Protocol• Terminology• Contrast• Radiation Safety• Cases
Normal CT
1 day 1 year 2 years
Normal CTOlder personNormal CT
Older Person
Normal Enhanced CT