Infection and Inflammation Flashcards
inflammation is (non/specific) response to injury.
nonspecific
infection is a response due to?
microorganisms present
infection without inflammation can occur in what kind of patients?
those that are severely immunocompromised
what is the relationship between infection and inflammation?
inflammation doesn’t always mean infection, but infections typically cause inflammation
when the body is responding to infections, what does the body start to release?
histamine, bradykinin, serotonin
what do chemical mediators do to the body?
increase blood flow and capillary permability
diapedesis
movement of cells into tissues through the endothelial cells of the capillaries
cellular phase of infection
chemotaxis causing local macrophages and neutrophils to go to the site
chronic phase of infection
arrival of lymphocytes (B, T and NK cells)
what inhibits the infection process?
alcohol, NSAID, corticosteroid meds
types of granulocytes
1.neutrophils
2. eosinophils
3. basophils
types of agranulocytes
lymphocytes and monocytes
ratio of RBCs to WBCs
1000:1
what is the WBC imaging exam of choice for vertebral osteomyelitis/diskitis?
Gallium WBCs
what is the WBC imaging exam of choice for pulmonary infections and sarcoidosis of the lungs?
gallium WBCs
what is the difference between 111In-Oxine and 99mTc-HMPAO in terms of them labelling WBCs?
Oxine allows for the In to enter the cells, then in the cell, oxine diffuses out leaving In to bind intracellularly
99mTc-HMPAO enters the cells then changes into a secondary complex which prevents it from diffusing out of the cells
when labelling WBCs, cells should be re-injected into patients within ____ of removal.
3 hours
99mTc-HMPAO vs. 111In-Oxine
which has superior imaging characteristics?
99mTc-HMPAO
99mTc-HMPAO vs. 111In-Oxine
Which is produced by a cyclotron?
111In-Oxine
99mTc-HMPAO vs. 111In-Oxine
Which is preferred for peds?
99mTc-HMPAO
99mTc-HMPAO vs. 111In-Oxine
Which is earlier imaging time?
99mTc-HMPAO
99mTc-HMPAO vs. 111In-Oxine
Which is better for extremities? Why?
99mTc-HMPAO
due to higher photon flux
99mTc-HMPAO vs. 111In-Oxine
Which is better for abdominal/pelvic imaging? Why?
111In-Oxine
due to absence of bowel activity
99mTc-HMPAO vs. 111In-Oxine
which is the agent of choice for osteomyelitis in a diabetic foot and prosthetic joints? why?
111In-Oxine
due to its ability to perform dual isotope imaging
99mTc-HMPAO vs. 111In-Oxine
which has lower body bkg?
111In-Oxine
99mTc-HMPAO vs. 111In-Oxine
which is the agent of choice for chronic infections?
111In-Oxine
where does 99mTc-HMPAO localize?
regular bone marrow and at the site of inflammation
where does 111In-Oxine localize?
at the red marrow
which leukocyte is most likely to be labelled due to its high abundance?
neutrophils
what is the acceptable %tag for labelled WBCs?
40-60%
what collimator is used when imaging with 111In-Oxine?
medium energy collimators
when do you routinely image when using 111In-Oxine?
at 24hrs
with 99mTc-HMPAO, what do we initially see for normal biodistribution?
lungs, liver and spleen
with 99mTc-HMPAO, what do we see at 1-2 hrs for normal biodistribution?
lungs, liver, spleen, bladder, kidneys, bone marrow, + sometimes gallbladder
with 99mTc-HMPAO, what do we see at 3-4 hrs for normal biodistribution?
lung activity is decreasing
but bowel activity can be seen
when do we see bowel activity in all patients using 99mTc-HMPAO?
at 24hrs
digital subtraction
subtracting the SC image from the In-WBC image that were acquired simultaneously
what scan needs to be done first when the indication is osteomyelitis?
3-phase
if the SC scans show uptake in the same area has the WBC scans, what does it mean?
it means that it is negative for infection as the SC is used to show BM.
if that area has uptake with SC, means it is the site of BM.
what can cause a false positive for infection/inflammation studies?
- GI bleeds
- post sx wounds show uptake for 2-3 weeks, unless intense or beyond time
what is the half life of 67Ga?
78 hrs
what are the 4 energies of 67Ga?
93, 185, 296, 388 keV
what does 67Ga-Citrate bind to?
transferrin in blood
how is 67Ga-Citrate excreted? when?
kidney and bowel in first 24 hrs
just bowel after that
at sites of infection, what does 67Ga-Citrate bind to?
lactoferrin
what releases lactoferrin?
dying leukocytes and bacterial siderophores
when using 67Ga-Citrate for imaging for abscess, when do we image?
6-24 hrs
when using 67Ga-Citrate for imaging for tumors, when do we image?
48-72hrs
when imaging with 67Ga, what does the lambda sign represent?
it is a common indicator for sarcoidosis if there is also prominent salivary gland uptake
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for chronic infections and FUO with no recent hx of sx?
67Ga
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for lung imaging and nonbacterial infections?
67Ga
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for vertebral osteomyelitis?
67Ga
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for abdominal imaging?
111In
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for acute infections?
99mTc then 111In then 67Ga
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for IBD?
99mTc
67Ga Citrate, 111In WBC, 99mTc WBC
which is better for extremities?
99mTc
