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45 Cards in this Set
- Front
- Back
X-Ray Radiographs
- what factors determine the density of an image? |
- composition (atomic number)
- thickness of the object - strength of the x-ray |
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What are the 4 basic radiographic densities (colors) represented on a film?
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Air = black
Fat = dark gray/black Water (soft tissue - organs, muscles, blood vessels, masses) = light gray Bone, calcium, metal = white |
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What contrast agents are used in x-rays?
How are they introducted? What color do they show up on films? |
Barium - ORAL
Iodinated contrast - IV *Show up white! |
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What is Computed Radiography (CR)?
Where are the images stored? |
Instead of a film, a phosphor plate is exposed to the x-rays --> light released is converted into an electron stream --> converted by a computer into a digital image, available over networks
- Images stored in PACS (picture archiving and communication system) |
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How is an Ultrasound image created?
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Transducer sends high frequency sound (1-20 megahertz) into body --> gathers the echoes --> converts into electronic signals displayed on monitor
- whatever the waves reflect off of appears white... sound waves go through fluid, which appears black |
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What are the advantages of US?
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- non-invasive
- no radiation (great for pregnancy) - relatively inexpensive and widely available - portable machines - good contrast of tissue layers in many organs - e.g., see follicles within ovaries - multiplanar imaging in REAL TIME |
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What are the disadvantages of US?
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- relatively small field of view
- air-filled structures and bone cannot be evaluated; obesity ruins sound beam - operator-dependent! reproducibility is bad - deeper penetration = lower frequency beams and lower-resolution |
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What is Sonohysterography?
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Saline injected into endometrial cavity before US --> improves quality and contrast bc fluid is excellent for US
- good for eval of endometrial cavity - bad for eval for tubal disease (need contrast agents that arent FDA approved) |
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How does one create a 3D US?
4D? |
3D: US beam is sent at multiple different angles and collected in different data sets --> computer puts it all together
4D: adds movement! |
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What is Doppler?
- what type of pelvic dx is it good for? |
special form of US used to evaluate BLOOD FLOW - presence, character, speed, direction
- can be used to evaluate vascularity and type of blood flow in mass (high/low resistance) - helps to dx ovarian torsion |
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What is CT/CAT?
What is used to improve contrast? |
= Computer Tomography/ Computer-Assisted Tomography
To improve contrast: - suspended respiration to minimize motion - iodinated contrast - oral contrast to opacify bowl loops - thin patients better - obesity degrades quality |
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What are the advantages of a CT?
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- large field of view - encompasses all structures in iamge from skin-to-skin
- high resolution with clear anatomy - less operator-dependent; more reproducible - ultra-fast! |
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What are the disadvantages of CT?
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- exposure to ionizing radiation
- relative lack of soft tissue differentiation - exc calcification or lots of fat - potential adverse rxn to contrast medium - reconstruction of images into multiplanar view takes time- not immediately available |
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What is a PET-CT?
- Use? - Disadvantages? |
Positron Emission Tomography + Computed Tomography
- uses F-18 (radioactive tracer) attached to FDG (glucose-like) molecule --> accumulates in malignant cells bc high rate of glucose metabolism **More sensitive than each of its components separately - Used to stage tumors and monitor responses to therapy - Disadvantages: high radiation exposure; EXPENSIVE |
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MRI
- how does it work? - possibly planes of images? - contrast agent? |
- radio waves 10,000-30,000 x stronger than earth's magnetic field are passed thru body --> forces hydrogen nuclei into different position --> as they move back into place, send out their own radio waves
- planes: coronal, axial, sagittal all possible - Gadolinium = contrast agent (low allergy rate) |
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Advatages of MRI?
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- large field of view from skin-to-skin
- no exposure to ionizing radiation - not as operator-dependent as US; more reproducible - the best soft-tissue contrast resolution!!!!! - including fat and hemorrhage |
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Disadvantages of MRI?
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- artifacts from respiratory motion and bowel peristalsis
- EXPENSIVE - time-consuming with complicated protocols - Gadolinium contraindicated in patients with renal failure - limited access - claustrophobia - tight squeeze for obese pts - need to understand the physics involved |
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In what patients is Gadolinium contraindicated? Why?
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RENAL FAILURE:
Increased risk of NSF = Nephrogenic Systemic Fibrosis - potentially fatal disease resulting in multiorgan fibrosis PREGNANCY: Cross the placenta |
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Which technique offers the BEST soft-tissue contrast resolution?
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MRI
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For what patients is it contraindicated to enter the MRI magnet?
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- ferromagnetic metallic objects/implants - e.g., cochlear implants, pacemakers, neuro stimulators, brain aneurysm clips, shrapnel, etc.
- Orthopedic devices are ok, but cause artifacts on image - IUDs are fine |
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What is the main use of plain film radiographs in women's imaging?
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delineation of large pelvic mass, detection of calcification
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What is HSG?
- Use? - MOA? - when should it be performed? |
= Histosalpingography
- used in work-up of infertility - MOA: radioopaque iodinated contrast material injected into uterine cavity thru cervix, then out fallopian tubes -- to assess patency of tubes and delineate uterine cavity - best performed during proliferative phase after period bc must avoid pregnancy (iodinated contrast) - approx day 6-10 of cycle |
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What are the main complications of HSG?
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cramping, pain, bleeding, infection, allergic rxn to contrast material, embolizations of air or contrast medium (**esp if oil-based medium is used; now usually use water-based)
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What is the imaging modality of choice for evaluating female pelvis/pregnancy??
= FIRST TEST ORDERED FOR GYN SX??? |
Ultrasound!!!
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What are the 2 methods of performing an ultrasound of the female pelvis?
Compare the two... |
Transabdominal Sonography (TAS)
- full bladder (discomfort) - larger field of view - structures displaced deeper by bladder--> less resolution - bladder pushes bowel loops out of the way, which allows for general pelvic overveiw - from outside abdomen, so can do mult scan planes and move transducer around; patient can move around Transvaginal Sonography (TVS) - empty bladder - smaller field of view - closer structures--> better resolution - limited mobility of transducer - vaginal narrowing can be a problem |
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What is the earliest that an ultrasound can detect evidence of pregnancy?
- what else can be seen in the first trimester? when? |
Earliest Detection = Gestational Sac = 4.5 weeks
Yolk Sac = 5.5 weeks **definitive sign Embryo = 6 weeks (2-3 mm length) Heart Beat = 6 weeks (Crown Rump Length - CRL = 5 mm) Gross Body Movements = 9 weeks |
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What type of Ultrasound can detect images earlier??
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TVS can confirm structures 1-2 weeks earlier than TAS
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How many vessels are within the umbilical cord?
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2 arteries
1 vein |
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What is the classic triad of findings of an ectopic pregnancy?
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1. abdominal pain
2. vaginal bleeding 3. adnexal mass |
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What does the density of a mass indicate about its malignancy?
What else? |
The more solid a mass, the more malignant...
Also, septations and ascites are bad signs |
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What imaging method is best for TRAUMA??
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CT!!!
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What is the relationship between CT scan and pregnancy?
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AVOID! Use only in dire situations bc ionizing radiation is harmful
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What is the "problem solver" imaging device- used when there are unusual findings in female pelvis?
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MRI!!!
= adjunctive test |
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What is the method of choice for staging cervical, uterine, vulvar, and vaginal carcinoma?
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MRI!
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Is MRI safe for pregnancy?
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Considered safe.
Avoided during first trimester bc rapid organogenesis and limited results of imaging this early |
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What is the imaging modality of choice for BREAST evaluation?
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x-ray mammography
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What are the recommendateions for the frequency of mammography screening?
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- Every year after age 40
- If first-degree relative with (premenopausal) breast cancer, screen yearly as early as TEN YEARS before - Don't generally use on women <30 bc increased sensitivity to radiation in immature breast |
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What are the American Cancer Society guidelines for the average woman's breast cancer screening?
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1. Monthly self-breast exam
2. Yearly physical exam by health professional 3. Annual mammogram after 40 |
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What is the difference between screening mammography and diagnostic mammography?
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Screening mamm = small amount of radiation, 2 views per breast
Diagnostic mamm = used to target a specific finding at another screening - e.g., clinical finding, symptom, screening mammography |
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What is the recall rate after a screening mammography?
What is the positive predictive value of mammography? |
Recall Rate = 10%
PPV = 15-35% (# cancers diagnosed per # biopsies recommended) |
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What are the routine views for breast mammography?
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- craniocaudal (CC: top-bottom)
- mediolateral oblique (MLO: side-side) |
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What does the ability of a mammogram to detect cancer depend on?
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- density of breast tissue
- size of tumor - skill of radiologist |
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What is the sensitivity of mammography?
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= 75% (less under 40 y.o. bc of denser breasts and faster growing tumors; better over 65 y.o.)
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What is the most common adjunctive method for breast imaging?
What else might be used? |
ULTRASOUND = #1 adjunctive
- differentiate cyst from solid - differentiate benign from malignant - guide biopsy - possibly use first for women <30 with palpable mass Contrast enhanced breast MRI is not as popular as US - differentiate post-surg scar from tumor - ***for silicone IMPLANTS - staging of known cancer - ambiguous mammography, sonography, clinical findings - **screening of women with >20% risk of br cancer - BRCA mutation or history of mediastinal irradiation in adolescence |
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What are the 2 molecular imaging techniques being studied for breast cancer research?
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BSGI = breast specific gamma immaging
PEM = positron emitting mammography |