Lecture 1 Flashcards
divides the brain into superior and inferior parts
horizontal/axial slice
another name for horizontal slice
axial slice
describe the horizontal slice
divides the brain into superior and inferior parts
like slicing bread
coronal slice
how is a CT/MRI image viewed
as if you are looking at the PT
as if the PT is lying on their back and their feet are directed towards you (you are standing at the PT’s feet)f
why are the eyes dark on imaging
there is fluid present in them
divides the body into left and right
sagittal slice
any vertical plane that divides the body into front and back
coronal/frontal slice
can audiologists order imaging
no
we can refer to the physician and recommend the tests are ordered for xyz reasons
Lab tests are helpful in
evaluating the health status of an individual
if your readings are abnormal, does that mean it is actually abnormal?
not necessarily
5% of healhty PT’s falls outside the normal range
reasons for abnormal results
Race
Diet
Age
Gender
Menstrual cycle
Degree of physical activity
Problems with collection/handling of the specimen
Use of non-prescription drugs
Use of prescription drugs
Alcohol intake
Illnesses
why are the norms based off of caucasians?
a lot of medical testing and research is done in first world countries and that is why data is based off of caucasians
what do blood tests test for
Blood sugar levels
Cholesterol levels
Infections
Electrolyte (potassium, chloride, etc.) imbalance
Minerals (e.g., calcium and phosphate)
Hemoglobin levels
Cardiac function
Renal function
Hepatic function
Markers for some diseases such as cancers and arthritis
Genetic tests
why is genetic testing performed in humans
Diagnose/rule out a genetic condition
Diagnose/rule out viral infection such as the novel Corona virus
Presymptomatic or predictive testing
Identifies the presence of variant genes that cause disease or increase disease risk, even if someone appears to be healthy
Establish risk factors for inherited diseases
Establish paternity
Prenatal diagnosis of genetic conditions
Medico-legal cases
Pharmacogenomics testing to predict the response to certain medications
Transplantation testing to determine whether an organ or tissue is a match for the transplant between a donor and recipient
what is A1C
hemoglobin test
blood cells replenish every 180 days so extra glucose is in your blood, because they have this turn around, it tells the avg of glucose over this period, more accurate marker for diabetes, gives a dynamic range
what can be an effect in elderly with low potassium if electrolytes are out of whack
affects the heart
& hearing
do they test an entire genome?
no
have to look for a specific gene and they will say whether you have it or not
How do you know if you have corona?
looked at genetics of the virus to see what you have
what is pharmacogenomics testing
talor making medicine to suit chemical makeup -
this will work for me or it won’t
asthma medicine will close the airways instead of opening them up during an attack
new branch of medicine combining genetics & pharmacology to create the best outcomes of medicine -
pharmacogenomics testing
Urine test/analysis is used to detect
Urinary tract infection
Kidney and bladder disease
Drug use/abuse, etc.
long term diabetes affects structures that have
capillaries (tiny blood vessels) & high blood flow (very vascular)
kidney failure is one of the major symtpms of this
diabetes
what is albumin in your urine
low levels can indicate kidney dysfunction
protein uria =
kidneys are not fxning well
risk averse in america, why?
because Dr. can be sued
so they go for the more expensive tests to make sure they do not miss anything
why do Dr.s choose MRI over an ABR for vestib schwanomas?
they will choose an MRI over the ABR (sensitivity is not as high in ABR than an MRI) and insurance would pay for the MRI but not ABR
what deters good medicine in the us?
transportation and cost
cheapest, around for a long time, limited use because of the other ones that give more info
x ray
3 main imaging techniques
x ray
ct
mri
which imaging has radiation
ct & xray
when you get a mammogram, is that a screening or diagnostic?
screening test
screen, mri, then biopsy
what is a biopsy
anything that is removed from the body to find the presence, cause or extent of a disease
examination of tissue, such as liver, bone, and tumors, removed from the body to discover the presence, cause, or extent of a disease
what is the GOLD STANDARD
biopsy
what is the most expensive and invasive test
biopsy
why do patient’s postpone procedures?
they do not have the $ to cover it
form of electromagnetic radiation, like visible light
x ray
have higher energy and can pass through most objects, including the body
x rays
what are medical x rays used to do
used to generate images of tissues and structures inside the body
How does an image form on an x ray
x ray travels through the body and passes through the x ray detector on the other side of the PT, creating an image that represents a shadow formed by objects in the body
what structures are the best for x ray. why
bony structures
it is hard so it weakens the light and shines as a lighter shadow and makes it more clear on an x ray
if you suspect a fracture of ossicles or otosclerosis they will do what
a CT
not an x ray because they are so tiny you cannot see on this
what is a CT
combines a series of X-ray images taken from different angles around the body
how does a ct work
uses computer processing to create cross-sectional images (slices) of the bones, blood vessels and soft tissues inside the body
what does ct stand for
computerized tomography
what is a ct used for
diagnose disease or injury, and to plan medical, surgical, or radiation treatment
Each CT rotation yields
several images of thin slices of the body part being investigated
what is a CT with a contrast
iodine injected in the veins and shows up differently
is there a blockage?
drawback of CTs
exposed to more radiation
explain contrast done in ct
Contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines, or other structures
how can contrast be taken
mouth
iv
enema
can contrast material cause allergic reactions?
yes, iodine based material
what does a ct image depend on
density of the tissue
what color is air on ct
black
what is more black on ct
fat
shades of grey on ct
fluid, blood, muscle, soft tissues
what is white on a ct
bone
what are the advantages of ct
Usually, a higher resolution than X-ray or MRI
Bone is seen better with CT for example, ossicles
Bone and air are well differentiated with CT
It is cheaper and faster
Better tolerated
what are some disadvantages of ct
Ionizing radiation; same risk as X-rays
Metal can present as artifact
Poorer soft tissue contrast, for example, nerves
More adverse reactions to the IV CT iodine-based contrast material used; greater risk of allergic reactions and renal problems
CT images are acquired only in the axial/horizontal plane
use extremely powerful magnets combined with electromagnetic fields and coils which produce radio waves, to produce detailed images of organs and tissues in the body
MRI
what does mri stand for
magnetic resonance imaging
based on the magnetization properties of atomic nuclei
mri
what is the cheapest option
x ray
What is T1 weighted MRI
Enhances the signal of the fatty tissue and suppresses the signal of the water
what is t2 weighted MRI
Enhances the signal of the water
how can you easily differentiate T1 & T2
by looking at the CSF
CSF is dark
T1
CSF is bright
T2
colors
fMRI
more blood flow to the area
more color on fMRI
Fat is bright and fluid is dark
T1
Fluid is bright on
T2
which is ideal for picking up tissue edema
t2
what is used in fmri
t2
what is the fmri
allows visualization of neural activity in the brain by detecting areas of increased blood flow
Bone and air are dark on
all sequences
Bone marrow is bright on
T1
what is the unit of measurement quantifying strength of magnetic field of an MRI
tesla (T)
what are the tesla ranges
.5-3.0 T
1.5 T is most common
what is the highest strength in humans of an mri
10 T (university of minnesota in 2018)
what are higher teslas available for
research
how are CIs affected by MRIs
have to take off the external magnet, the internal magnet and put the Cochlear Nucleus Implant bandage & splint kit you can go into a 1.5T
if you have to go up to 3 T you have to have the implanted magnet removed surgically
how are BAHA affected by mri
remove sound processor
new device approved for up to 3 T
what disorder is an ABI used for
Bilateral schwanomas = NF2 = sacrifices both cochlear nerves, so ABI is the procedure
the only FDA approval use for ABI
NF2
(neurofibromatosis)
how is ABI affected by MRI
outer magnet is removed and can withstand up to 1.5T
it is designed to be compatible with mri
higher level mri is contraindicated and unable to perform because it will cause tissue damage
advantages of mri
most used in neurology and neurosurgery (head and neck issues)
escellent tissue contrast
contrast material (dye-iodine vs. gadolinium) detection is superior to the CT scan, also non-iodine-based gadolinium causes less allergic reactions and renal problems
visualize anatomy in all three planes; axial (horizontal), sagittal, and coronal
posterior fossa is more easily visualized on MRI than CT
No ionizing radiation required; no radiation risks
Non-invasive
More sensitive for tumor detection and detection of small soft tissue structures than CT scan
Detection of acute ischemic stroke (within 12 hours of onset)
Sensitive to detection of old blood, e.g., hemorrhagic strokes
higher teslas are more expensive
yes
disadvantages of mri
Expensive
It cannot distinguish between air and compact bone
Longer exam time than CT - no movement for 3 to 7 minutes
Metal artifacts
Patients may suffer from claustrophobia
are open mri units as sensitive
may not be
blood vessel ruptures and blood pools into the brain & more common
hemmorragic
blood supply to part of the brain is blocked or reduced & less common
ischemic
what are contraindications of MRI
implanted electrical devices such as pacemakers, CIs, & ABIs
if you are suspecting an acoustic neuroma, what do you do
recommend an MRI
nerve visualization
MRI
Congenital bony anomalies, dehiscence, bone lesions (osteospongiosis), otosclerosis
CT
Cholesteatoma and middle ear tumors
both ct and Mri
Pre-operation evaluation for cochlear implant
Usually CT but MRI can be used too
Trauma such as skull fractures
CT
Mastoiditis, malignant otitis, strokes, cholesterol granuloma, arterial and venous anomalies, pulsatile tinnitus
CT & MRI
what is pulsatile tinnitus
tinnitus that follows the heart beat
i hear my heart in my ears
pulsatile tinnitus
why is pulsatile an issue?
it is not an ear problem
it is a blood vessel problem
Carotids obstruction etc. can lead to heart issues, strokes, etc.
