Imaging and Clinical Applications Flashcards
4 things that should be done for all patients’ studies
- Verify patient identity (patient name matches on study)
- Verify date/time of study is correct
- Verify study type i.e. x-ray/CT/MRI is correct
- Get older study or record for comparison
Steps 1-3 = ALWAYS DO, Step 4 = Optional but ideal
What are the 4 types of radiological studies?
- Plain x-rays
- CT scans
- MRI
- Ultrasound
What is an orthogonal x-ray?
X-ray taken at 90 degrees
Commonly ordered X-ray views for:
Chest (3)
- PA or AP
- Lateral
- Portable
Commonly ordered X-ray views for:
UE (3)
- AP (frontal)
- Lateral
- Oblique (let’s you see things between AP & lateral)
Commonly ordered X-ray views for:
LE (3)
- AP (frontal)
- Lateral
- Oblique (let’s you see things between AP & lateral)
Commonly ordered X-ray views for:
Abdomen (4)
- Supine
- Upright
- Decubitus
- AAS
Commonly ordered X-ray views for:
Pelvis (3)
- AP (inlet/outlet)
- Lateral
- Frog-leg
Commonly ordered X-ray views for:
Facial B./Skull (4)
- Frontal
- Lateral
- Upright Water’s
- Nasal Views
Commonly ordered X-ray views for:
Cervical spine (5)
- AP
- Lateral
- Oblique
- Flexion/Extension
- Open-mouth
Commonly ordered X-ray views for:
Thoracic spine (3)
- AP
- Lateral
- Oblique
Commonly ordered X-ray views for:
Lumbar spine (3)
- AP
- Lateral
- Oblique
Commonly ordered X-ray views for:
Sacral spine (1)
- AP (inlet/outlet) same as pelvis
- Caveat: low sensitivity
Ideal imaging modality for sacral spine
CT
Ideal imaging modality for neurologic injuries
MRI
Order the following from least dense to most dense:
- Soft-tissue
- Bone
- Air
- Metal
- Fat
- Air
- Fat
- Soft-tissue
- Bone
- Metal
Match structure to expected appearance on plain films:
Air, fat, soft-tissue, bone, metal
- Very bright (very white)
- Dark (black, radioluscent)
- Bright (white)
- Less dark, but still dark
- Medium (gray)
- Air = dark
- Fat = less dark, but still dark
- Soft-tissue = medium (gray)
- Bone = bright
- Metal = very bright
Distinguish between a PA and AP view
- where is beam traveling from?
- where is film that beam is traveling to and hitting?
- PA view
- beam traveling from back (P) and hitting film in front (A)
- AP view
- beam traveling from front (A) and hitting film back (P)
PA or AP view, which is preferred in majority of chest cases?
Why?
Under what circumstances is the other usually ordered?
- PA view
- AP view can give enlarged view of heart & vessels leading to false cardiomegaly dx
- AP view usually ordered when unable to position patient erect as needed for PA
Fractures are easily identified on plain films by looking for ______ (outer portion of B.) disruptions
Cortical disruptions
Fluid is ______ dense than air and therefore appears _____
more dense than air and therefore appears medium gray to bright white
Calcifiied structures that appear dense and bright on abdominal x-rays?
kidney stones
4 patterns of plain film misdiagnosis?
- Nml ____ & _____
- _____ recognition failure
- Associated _____
- Suboptimal _____ & number of ______
- Nml anatomy & variants
- Pattern recognition failure
- Associated pathology
- Suboptimal positioning & number of projections (only visible on certain view, all other views nml)
- Presence of what structure visualized on an x-ray can indicate the patient is a child?
- What does it look like?
- Growth plate
- Smooth, radioluscent line
2 imaging modalities that present with ionizing radiation risk
- X-rays
- CT scans
Order the following from least hounsfield unit (HU, aka x-ray beam) absorbed to most HU absorbed on CT.
- H2O
- body fluid, i.e. ascites
- blood
- fat
- air
- bone/metal
- air (least dense, -800 HU)
- fat (-70 HU)
- H2O (0 HU)
- body fluid, i.e. ascites (0-20 HU)
- blood (40-60 HU)
- bone/metal (800+ HU)
On CT dense structures appear? less dense structures appear?
- Dense structures appear white
- Less dense structures appear darker
Different _____ in CT enables evaluation of different organs within single image.
windowing
Almost all CT scans are acquired in what plane?
axial plane
how are 3D or coronal, sagittal, and oblique plane images acquired in CT scans?
through reformatting and stacking of axial scan images
3 things useful for clinicians to know when evaluating CT images?
- slice thickness
- location of 1st and last slices
- type of contrast used
How is CT angiography similar to conventional angiography?
How is it different?
Similar: obtain same info, radiation exposure, IV contrast use
Different: less invasive
How is CT angiography different from basic CT?
- need faster scanner
- need larger needle size to get faster IV contrast injection rate
How does water appear on T2 MRI images?
Remember WWII:
Water appears White on T2 (II) images
How does water appear on T1 MRI images?
Black (opposite of T2)
How do tumors and inflammatory masses appear on T2 images?
white
Advantages of MRI:
- Greater ____ of soft tissue
- Acquired _____
- Get vascular study _____
- No _____
- Greater differentiation of soft tissue
- Acquired in any plane
- Get vascular study without IV contrast
- No radiation exposure
Disadvantages of MRI:
- Longer ______
- Very sensitive ______
- longer aquisition time
- very sensitive motion artifact
Advantages of U/S:
- No ____
- Acquired _____
- Less ____
- Performed at _____
- Provide ____ imaging
- No radiation exposure
- Acquired in any plane
- Less expensive
- Performed at bedside
- Provide real-time imaging
Disadvantages of U/S:
- Less _____ images
- Takes _____ than CT
- ______ depending on operator skills
- ______ are 2 structures not visualized well in U/S
- Less sharp & clear images
- Takes more time than CT
- Highly variable quality and accuracy depending on operator skills
- Bones and lungs are 2 structures not visualized well
What is the concern w/ CT imaging in pregnant women?
Ionizing radiation exposure to fetus
What is the concern w/ MRI in pregnant women?
Field strength (1.5T vs 3T) can potentially heat fetal/amniotic fluid
What are 3 contrast agents that should be avoided when imaging pregnant women?
- iodinated contrast
- oral contrast
- gadolinium
