HIGH YIELD II

Question 1

the triphasic technetium scan improves?

Answer 1

specificity

Question 2

what are the phases of triphasic technetium scan?

Answer 2

phase 1-dynamic images
phase 2-blood pool image
phase 3-delayed/static image
phase 4-24 hour delay

Question 3

name this phase of the technetium scan?

series of rapid 2-5 second images as tracer passes through vascular compartment (perfusion)

bulk of tracer is intravascular-radionuclide angiogram

strong gradient towards ECF

Answer 3

phase 1, dynamic images

Question 4

name this phase of the technetium scan?

after 5 min, 20-30% of injected tracer remains intravascular

images acquired after 5-15 min

reflects tracer redistribution into ECF, relative hyperemia

areas of inflammation cause capillaries to dilate, increasing blood flow

Answer 4

phase 2, blood pool image

Question 5

name this phase of the technetium scan?

after 4 hours, 55-60% of the initial dose is retained in skeleton, remaining 30-40% excreted via urine

reflects relative bone turnover

retained ECF tracer=unwanted background noise

Answer 5

phase III, delayed/static image

Question 6

name this phase of the technetium scan?

uptake in the lamellar bone ends at 4 hours and continues next 24 hours in woven bone

higher lesion to background ratio

PVD, vascularity compound

Answer 6

phase IV, 24 hour delay

Question 7

complicating factors of bone scans?

Answer 7

active sterile inflammation

• recent fracture
• diabetic foot
• neoplasm

early neonatal HOM

septic arthritis

false negatives w/ AB tx

Question 8

what are the reliability issues with bone scans?

Answer 8

remain hot for 9-12 months after major bone trauma, not 6 months

Question 9

for bone scans, how do we improve specificity?

Answer 9

sequential scanning via

scintigraphic modalities
gallium
WBC scans
antibody labeled WBCs

Question 10

what is the main mechanism of uptake with gallium scanning?

Answer 10

used as an inflammatory scan that binds to transferrin

also lactoferrin, found in high concentrations in inflammatory foci

Question 11

what is significant of Ga in OM imaging?

*when may it be more accurate?

Answer 11

2 isotopes with mulitple imaging sessions over many days

high radiation dosage

more accurate in monitoring OM therapy

vertebral OM

*monitoring therapy

Question 12

what does indium scanning look for?

Answer 12

WBC scan, non inflammatory

Question 13

indium scanning technique?

Answer 13

40-50 ml blood drawn and sent out

WBCs separated

re-inject into patient 2-3 hrs later

scan pt 24 hrs later

Question 14

when does indium photopeak? Tc?

half life of indium vs Tc?

Answer 14

173/247 keV, 140 KeV

2.8 days, 6 hrs

Question 15

T/F, for indium scanning, labeled WBCs do not usually accumulate at sites of increased bone mineral turnover in the absence of infection?

Answer 15

T

Question 16

major problems with in-WBC scanning?

Answer 16

rapid forming non-infected DNOAP
indium localization occurs at non-infected acute fracture sites
not bone seeking resulting in poor spatial resolution

Question 17

in labeled WBCs determine? Tc images provide?

Answer 17

presence of infection, providing sensitivity and specificity

anatomic detail like infection of bone, ST, both

Question 18

T/F, in Charcot arthropathy, WBC uptake within bone cannot automatically be equated with OM?

this leads to false positives, name some?

Answer 18

T

acute fracture
increased bone remodeling
fibre-osseous metaplasia

Question 19

name some disorders associated with increased WBC uptake?

Answer 19

acute fracture
active RA
Charcot joints
displacement or reactivation of marrow
heterotrophic bone
acute bone infarction

Question 20

what was the affect of Charcot pathology on marrow?

Answer 20

usually inactive, but yellow marrow is turned into red active marrow

• active post traumatic arthropathy
• early post op changes can lead to ectopic active marrow

Question 21

this type of marrow scan doesn’t have a tendency to accrete in infected marrow and provides an accurate map of active red marrow, exudes infected marrow? asymmetry indicates?

why is indium important?

Answer 21

Tc-sulfur colloid scan; infection
*labeled WBC activity outside normal marrow distribution represents infection

used to detect both sterile and infected reactivated marrow, reactivation can cause false positive indium scans

Question 22

this is a reliable way to diagnose marrow from infection and is superior to T3 bone or Tc/In scanning?

Answer 22

WBC/marrow scintigraphy