S1_L2_MSKI - 7-10 Flashcards
CORTICAL bones are __ in MRI
dark
bursa appears __ in t2
white
in t2 mri of the shoulder, it will look __
dark bc of fat conteent
ELEMENTS OF AN MRI SCANNER
magnet
gradient coils
rf coils
workstation
computer
Rests within a gantry large enough for the
human body and within the necessary receiver coils
magnet
The magnet has a field strength of around _ Tesla
0.3 – 3
1 Tesla = __ time the Earth’s magnetic field
20,000
_are also common where the patient is not fully surrounded by a magnet
Open scanners
how many gradient coils
3
Three gradient coils, one for each
__ are located within the _ of the MRI unit
orthogonal plane, core
The _ produce sequential
variations in the magnetic field that are used for providing _
gradient coils, spatial info
RF COILS serves 2 prposes
○ (1) Transmission of RF pulses that alter
the alignment of the protons
○ (2) Receive the signals emitted from the
protons
Send and receives radiofrequency, which
in turn uses it to create pictures of the
body
rf coils
Encircles the patient for the reception of larger areas
such as the hip, spine, and pelvis
● Body Coil
gradient coil is Too large for the resolution of smaller joints t or f
f, rf coil
Imaging protocols are selected by the MRI technologist or
radiologist prior to imaging
WORKSTATION
Directs the scanning process, converts data from
the RF coils and reconstructs the images
COMPUTER
computer converts data from __
rf coils
Direct of the scanning process, converts the data that is
received by the radiofrequency
coils and reconstructs it
computer
Greater ability to scan
claustrophobic/obese patients in MRI
open scanners
Reduction of scanning noise in what ype of mri scanner
open scanners
Ability to examine joints in WB conditions
to be able to detect protrusions,
herniations and spinal stenosis
upright scanners
Possibilities for performing tests or
procedures during scanning
open scanners
there is _ field strength, requiring adjustment of imaging sequences in open
scanner
lower
there is higer signal to noise ration in open scanners t or f
f, lower
○ Longer scanning times in open scanners t or f
t
Ability to examine patients too big to fit into the bore of the
magnet or must be scanned in the upright position for patients
with medical conditions such as
heart failure or seer thoracic kyphosis
UPRIGHT SCANNERS
Longer scanning times in both upright and open t orf
t
Possible image degradation in open t or f
f, iin upright
Placement of the patient in a painful
position which may increase movement which will
lead to decreased image quality in open t or f
f, in upright
As much as possible, you can move in MRI t or f
f, cannot move in MRI
Coronal Images are viewed from the _ (facing the patient)
front
● Axial images are viewed from _
below
Sagittal images are viewed from _
for either side of the body
left to right
T1: FAT
high signal intesnity
T1: free water
low signal intesnity
T1: red bone marrow
intermediate intensity
T1: yelllow bone marrow
high signal intesnity
T2: fat
intermediate singal density
T2: free water
high signal intesnity
T1/T2 for tnedons lig, menisci
Low signal intensity
T1/t2: cortical bone
Low signal intensity
T1: muscles
internmediate signal intensity
T2: muscles
intermediate but slghtly lower
T1: cartilage
intermediate
T2: cartilage
intermediate
T1: acute
high signal intensity
T2 acute
low to moderate signal intensity
Moderate to high intensities on both T1
and T2 weighted images in what hemorrhage
subacute hemrrohage
t1 chronic hemorrhage
variable intesnity
t2 chornic hemorrhage
high signal intesnity
INFLAMMATION & OTHER PATHOLOGY
THAT INC FREE WATER CONTENT in T1
low signal intesnity
INFLAMMATION & OTHER PATHOLOGY
THAT INC FREE WATER CONTENT in T2
increased signal intensity
PROLIFERATED SYNOVIUM ASSOCIATED WITH RA in T1/T2
● Intermediate to high density on both
Associated with infiltration of fate and fluid
muscle atrophy
t1 t2 muscle atrophy?
Increased signal intensity on T1 and T2
weighted images
Contain little to no free water in _
soft tissue calcifications
t1/t2 of soft tissue calcifications
low siignal intesnity
SOFT TISSUE TUMORS has __
high free water content
t1 soft tissue
low signal intesnity
t2 soft tissue
high signal intesnity
BONE TUMORS t1/t2
Various intensities, depends on osteolytic or osteogenic
Displayed as straight or serpingious (worm-like) lines of
low signal intensities on both T1 and T2
ACUTE FRACTURES
These lines are typically surrounded by _ in acute fx
bone marrow edema
t1 acute fx
low singal intesnity
t2 acute fx
high signal intesnity
May display as bone bruises,
stress fx
t1 stress fx
low signal intesnity
t2 stress fx
high signal intensity
MRI Has replaced _ for the detection of meniscal tears
athroscopy,
t or f use ct scan for Disc herniation and nerve root impingement
f, mri
Ability to stage neoplasms in bone and soft tissues as well as the
extent of soft tissue
invasion
mri
Soft tissue detail esp for sports injuries such as tendons,
ligaments, menisci, etc.
mri
Changes and variations in bone marrow for the
diagnosis of bone tumors, stress fractures, and avascular necrosis
mri
LIMITATIONS OF MRI
● Imaging of cortical bone
● Length of time needed to produce and image
● High cost for imaging
CONTRAINDICATIONS & HEALTH CONCERNS
● Ferromagnetic surgical clips can be displaced
● Orthopedic hardware can cause image
distortion
● Possible malfunctioning of a pacemaker
within or near the magnetic field
● Claustrophobia
● Children and patients who are not able to stay
still need to be sedated
Displacement of brain aneurysm clips
can cause __
fatal hemorrhages
Creates images based on the radiodensity of tissues
CT SCAN
Creates images based on the energy emitted from
hydrogen protons in water or soft tissues
MRI
● Less expense
● Greater availability
● Faster imaging times
● Thinner slices
● Less loss of image
quality owing to
motion
● Easier imaging of
individuals with metal implants
CT SCAN
● Greater contrast resolution for soft tissue imaging
● Greater ability to image organs surrounded by dense bones structures
● No ionizing radiation
● Less risk of missing disease processes missed by one sequence are picked up
by using another sequcne
MRI
