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69 Cards in this Set
- Front
- Back
Is there a single CT protocol?
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No, they vary by facility, radiologist, machine, and/or patient condition
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What's the most common type of CT exam?
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Head
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What are the differences between a diagnostic x-ray tube & a CT x-ray tube?
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CT has more kVp range & absorbs and eliminates heat more efficiently
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What does the box represent on a CT scout image?
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Range of tissues
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What line should the slices be parallel to on head?
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Supraorbital meatal line (reduce radiation exposure to eye)
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What are the only exams that use a Gantry tilt?
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Head/Brain exams
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Why is the scout CT scan performed?
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Better center the patient to Gantry hole
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What is the "step-and-shoot" method?
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Tube goes around 1 rotation & makes a full acquisition/ circumference, then table moves
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Window width controls....
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The number of shades of gray (contrast)
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Window level (center) controls...
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Brightness
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What exam is the helical mode of a CT machine used for?
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Studies that require 3D reformations or CT angiography
Neck studies ex. Circle of Willis studies |
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Intracranial Hemorrhage (ICH)
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- CT is most frequent initial exam done for this
- appears hyperdense for first 3-10 days - appears isodense from 11 days - 6 months - appears hypodense after 6 months |
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What's the pharmacologic treatment for acute ischemic stroke?
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Tissue plasminogen activator (t-PA)
Must be administered within 3 hours of stroke |
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What kind of stroke should t-PA NOT be used for?
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Hemorrhagic stroke
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What type of CT scan is done to differentiate between hemorrhagic & ischemic stroke?
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Non-contrast Head CT
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How is a CTA better than traditional angiography for the head & neck?
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Less invasive, widely available, less expensive, time-saving
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What is the goal of a CTA exam of the head & neck?
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- accurately measure stenosis of carotid & vertebral arteries (and branches)
- evaluate circle of Willis |
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Why are CT scans of the sinuses done?
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- inexpensive, accurate, low radiation dose method for confirming the presence of inflammatory sinonasal disease
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How is the patient placed for a CT exam of sinuses?
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Prone to look for fluid levels
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Pitch
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- quantity of table movement to rotation
- tells you how spread out the helical acquisition will be |
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A pitch less than 1 indicates...
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There's an overlap of slices (desirable)
- increases patient dose but increases accuracy of measurements |
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What are beta-blockers used for in CT?
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- lower the heart rate to make rhythm more regular for cardiac CT
- have to get an order from patient's physician |
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What is multiphasic CT imaging used for?
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- pancreas, liver, kidneys, some abdominal studies
- images reviewed in 2 or more window settings |
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How is CT used for imaging the musculoskeletal system?
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- useful for evaluating bone & soft tissue tumors
- useful for evaluating joints (especially w/ contrast) |
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How long has vascular imaging been around?
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Over 5000 years old
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Who performed the first cardiac caatheterization on a horse in 1711 AD?
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Hales
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Who coined the term "cardiac catheterization"?
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Claude Bernard
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Who performed the first human cardiac catheterization in 1929?
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Dr. Werner Forssman (performed it on himself, used urinary catheter)
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Who coined the brachial approach for catheterization in 1959?
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Dr. Mason Sones (used dog hearts)
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Who came up with the idea of pre-shaped catheters?
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Dr. Melvin Judkins
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Who's the grandfather of angioplasty?
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Dr. Andreas Gruntzig
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What's the differences between cardiac lab & specials lab?
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Cardiac Lab --> cardiologist, see cardiac vasculature
Specials Lab --> radiologist, see internal aspects of organs (non-vascular) |
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Which type of catheter almost always has side holes?
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Pigtail
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Retrograde Administration
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Against the flow
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Antegrade Administration
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With the flow
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Intrathecal Administration
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Into a sheath (ex. Myelogram)
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Parenteral Administration
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Into a vessel (anything that's not oral)
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Difference between Medical & Surgical Asepsis
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Medical --> microorganisms have been eliminated (normal hand washing)
Surgical --> taken microorganisms & spores and destroy them w/ heat & chemicals (5 mins) |
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Where are the sterile lines?
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Waistline/Table Height & Gown sleeves/Waistline
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What's the patient prep & room setup for specials?
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- ensure correct approach
- palpate pulse/locate anatomy - trim hair & prep patient (Iodine vs. Cl/OH based) - drape patient & equipment |
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What does a specials procedure team consist of?
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Physician, scrub tech, circulator (in charge of equipment), nurse, recorder
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What 3 medications need to be stopped at some point before a specials/cath lab procedure?
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Heparin, Kumadin/Warferen, & Aspirin
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What lab values that relate to kidney function need to be obtained before a specials/cath lab procedure?
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BUN (blood urea nitrogen)
Creatinine GFR (Glomerular Filtration Rate) |
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What lab values that relate to blood clotting ability need to be obtained before a specials/cath lab procedure?
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Prothrombin Time
Partial thromboplastin Time INR (International Normalized Ratio) |
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What are risk factors for specials/cath lab procedures?
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- anuria
- history of previous MI - heart failure - previous contrast reactions |
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What levels must be monitored before, during, & after the specials/cath lab procedure?
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EKG, pulse ox, BP, respiratory rate, LOC, continuous IV access, supplemental O2, crash cart
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What's the difference between the cutdown approach & the percutaneous approach?
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Cutdown --> old method, cut down skin to expose vessel, slice opening into vessel & slide catheter in
Percutaneous --> cleaner, safer, less blood loss (Seldinger/Modified Seldinger sticking methods) |
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Which artery is most often used in the percutaneous approach?
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Femoral
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When are vitals taken after a specials/cath lab procedure?
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1st Hour: every 15 min
2nd Hour: every 30 min Next 4 hours: 1 per hour |
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Where do the most common complications from a specials/cath lab procedure occur?
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At the puncture site
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What complications can renal arteries cause?
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Renal arteries vasoconstrict when they have contrast media in them, can become a temporary lesion & cause ischemia to kidneys
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When was NMR (nuclear magnetic resonance) discovered?
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1946 by Bloch & Purcell
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When was NMR fully medically accepted?
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1967 (Jasper Johns)
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What is NMR?
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Interaction between nuclei w/ non-zero magnetic moment (something that has magnetic susceptibility/permeability) & an external magnetic field
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When is NMR observed?
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When the nuclei in a system are disturbed by an oscillating magnetic field (a radio frequency pulse) w/ a frequency equal to the procession frequency ω0
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What does 1 Tesla equal in Gauss?
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10,000 Gauss
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What's the magnetic field of Earth?
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0.31-0.58 Gauss
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What are the 3 things you need for MRI?
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Hydrogen Proton
Large static magnetic field Radio Frequency Signal |
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Why is hydrogen used for the majority of diagnostic MRI imaging?
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- most numerous element in body
- has large magnetic moment & large angular momentum |
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What are examples of high signal intense areas on T1 & T2?
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Fat or Blood
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What are examples of low signal intense areas on T1 & T2?
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Air (sinuses, lung, bowel) & cortical bone
Can also be indication of fibrous tissue |
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Explanation of what happens to protons in MRI
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When the nuclei are placed in a magnetic field, the protons will align themselves at discrete energy levels (called Zeeman energy levels) parallel or antiparallel to the magnetic field
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Where will a slight excess of protons be, the parallel or antiparellel direction?
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Parallel (lower energy)
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Precession
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- compared to rotation of a spinning top tilted on its axis
- top not only spins on its axis, but also rotates in a circular path around the up/down direction |
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Larmor Frequency Equation
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ωø = γ Bø
γ is the gyromagnetic ratio in MHz/Tesla Bø Is the magnetic field in Tesla (1T = 104 Gauss) |
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Resonance (Resonance Frequencies)
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- tendency of a system of oscillate at a greater amplitude at some frequencies than at others
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T1 time is...
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Time taken for the longitudinal magnetism to grow about 63% of its original value
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T2 time is...
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Time taken for the transverse magnetization to decay about 37% of its original value
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Name the cranial nerves in order
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Olfactory / Optic / Ocular Motor / Trochlear / Trigeminal / Abducens / Facial / Auditory / Glossopharyngeal / Vagus / Accessory Spinal / Hypoglossal
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