Radiology Department, Faculty of Medicine

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BASIC

NEURORADIOLO

GY

Sianny Suryawati

Radiology Department, Faculty of Medicine Wijaya Kusuma University, Surabaya

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Outline

• _{Normal Imaging Anatomy of Brain}

• _{Basic Features of Brain Lesions}

• _{Brain Tumor}

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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}

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Anterior circulation

Internal Carotid

Arteries

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Neuroradiology Modalities :

• _{Plain Film}

• _CT

• _US

• _MRI

• _{Interventional}

• _Angiography

• _Myelography

• _Biopsy

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CT Basics

• Neuroradiology

• The

BASICS

of CT

• _{CT History} • _Protocol

• Terminology

• _Contrast

• Radiation Safety

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SIR GODFREY N. HOUNSFIELD

• _{1979 Nobel Laureate}

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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

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CT History

• _{2004 – 64 slice scanner}

• _{1024 x 1024 matrix} • _{0.33s per revolution}

• _{64 images per revolution} • _{0.4mm slice thickness}

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CT Basics

• Neuroradiology

• The

BASICS

of CT

• Terminology

• _Contrast

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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 confrmed.}

• _{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}

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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

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CT Protocolling

• Variables

• Plain or contrast enhanced

• _{Slice positioning} • Slice thickness

• _{Slice orientation}

• Slice spacing and overlap

• Timing of imaging and contrast administration

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CT Protocolling

• Patient Information

• Is the patient pregnant? • _{Radiation safety}

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CT Basics

• _{Neuroradiology}

• _The

_BASICS

_{of CT}

• _Terminology • _Contrast

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CT Terminology

• _{Exams using}

_{Ionizing radiation}

• _{Plain flm} • CT

• _{1/10 of all exams}

• 2/3 OF RADIATION EXPOSURE

• Fluoroscopy

• _{Angiography, barium studies}

• Nuclear medicine

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CT Terminology

• _Attenuation

• _{Hyperattenuating (hyperdense)} • _{Hypoattenuating (hypodense)} • _{Isoattenuating (isodense)}

• _{Attenuation is measured in Hounsfeld units}

• _{Scale -1000 to 1000}

• _{-1000 is air} • _{0 is water}

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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 calcifcation (>300)

• Contrast

• Hemorrhage (Acute ~ 70)

• Hypercellular masses

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CT Terminology

• _Voxel

• _{Volume element}

• _{A voxel is the 2 dimensional representation of a 3}

dimensional pixel (picture element).

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CT Terminology

• _{Window Width}

• _{Number of Hounsfeld units from black to white}

• _{Level or Center}

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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

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CT Terminology

• _DICOM

• _{Digital Imaging and Communications in Medicine} • _{DICOM provides standardized formats for images, a}

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CT Basics

• Neuroradiology

• The

BASICS

of CT

• Terminology

• _Contrast

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Contrast

• _Barium

• _Iodinated

• _vascular

• _{Biliary, Urinary} • _CSF

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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

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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

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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.

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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}

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Contrast

• _{What are the risk factors for contrast induced}

acute renal failure?

• _{Pre-existing renal insufciency} • _{Contrast volume}

• _Dehydration • _{Advanced age} • _Drugs

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Contrast

• _{Considerations in patients with renal insufciency}

• _{Is the exam necessary?}

• _{Is there an alternative exam that can answer the}

question?

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Contrast

• _{Pretreatment for renal insufciency}

• _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.

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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.

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CT Basics

• Neuroradiology

• The

BASICS

of CT

• Terminology

• _Contrast

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Radiation Safety

• _{Diagnostic CT Scans: Assessment of Patient,}

Physician, and Radiologist Awareness of Radiation

Dose and Possible Risks

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Radiation Safety

• _{Deterministic Efects}

• _{Have a threshold below which no efect will be seen.}

• _{Stochastic Efects}

• _{Have no threshold and the efects are based on the dose x}

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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)}

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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}

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Radiation Safety

• _{Efects of X rays.}

• _{Absorption of photons by biological material leads}

to breakage of chemical bonds.

• _{The principal biological efect results from}

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Radiation Safety

• Tissue/Organ radiosensitivity

• Fetal cells

• _{Lymphoid and hematopoietic tissues; intestinal}

epithelium

• _{Epidermal, esophageal, oropharyngeal epithelia} • Interstitial connective tissue, fne vasculature

• Renal, hepatic, and pancreatic tissue

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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

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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 off loe doses off ioiisiig radiatioi ii iiffaicy oi cogiitive ffuictioi ii adulthood: Seedish populatioi based cohort study

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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 ofspring, including: congenital abnormalities, mortality (including childhood

cancers), chromosome aberrations, or mutations in biochemically identifable genes.

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Radiation Safety

• _{Hiroshima and Nagasaki}

• _{However, exposed individuals who survived the acute}

efects were later found to sufer increased incidence of cancer of essentially all organs.

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Radiation Safety

• _{Hiroshima and Nagasaki}

• _{Most victims with high doses died}

• _{Victims with low doses despite their large numbers are}

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Radiation Safety

Comparison of Image Quality Between Conventional and Low-Dose Nonenhanced Head CT

Mark E. Mullinsa, et al.

AJNR April 2004.

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Radiation Safety

• _{What does all this mean?}

• _{1 CXR approximates the same risk as:}

• _{1 year watching TV (CRT)}

• _{1 coast to coast airplane fight} • _{3 pufs on a cigarette}

• _{2 days living in Denver}

• _{1 Head CT is approximately 20 CXR}

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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

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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}

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Conclusion

• _{CT Terminology}

• _{Attenuation (density) in Hounsfeld units} • _{Digital interpretation is standard of care}

• _{CT has risks}

• _Contrast

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CT Basics

• _{Neuroradiology}

• _The

_BASICS

_{of CT}

• _Terminology • _Contrast

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Normal CT

Older person

_{Normal CT}

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