TU Imaging Flashcards
three NE tumors
pheochromocytoma, neuroblastoma, paraganglioma
paraganglioma
pheochromocytoma occurring by the adrenal
pheochromocytoma
benign and in the adrenal medulla
neuroblastoma
malignant and typically, when it presents itself, mets has already occurred
accounts for 10% of all childhood ca
dose of 123I-mIBG
typically, 370 MBq
dose of 131I-mIBG
40-80 MBq
peds dose
5.2 MBq/kg, max 370 MBq
mechanism of uptake for 123I/131I-mIBG
taken up in chromaffin cells by active transport
123I/131I-mIBG is an analogue of?
norepinephrine
purpose of pretreating pts with SSKI?
decreases thyroid uptake
injection to imaging time with 123I-mIBG
24 hrs
injection to imaging time for 131I-mIBG
24 and 48 hrs
half life for 131I
8 days
half-life for 123I
13.2 hrs
what collimators are used?
MEAP/HEAP
energy for 123I
159 keV, no beta emission
energy for 131I
364 keV, with beta emission
where are neuroblastomas usually found?
1/3 in adrenals
1/3 in abdomen
1/5 in chest
NE have high density of SSTR. which subtypes do the analog of somatostatin labelled with 111In have an affinity for?
subtype 2 and 5
carcinoid syndrome
symptoms due to the release of too much serotonin
carcinoid crisis
severe case of flushing, low BP, difficulty breathing and irregular heart beat
111In-Octreoscan/Octreotide is an analogue of?
peptide somatostatin
when do we image when using 111In-octreotide?
at 4-6 hrs, 24hrs and sometimes 48 hrs if requested
what are the energies that 111In has?
173 and 247 keV
mIBG is used for adrenal NETs only. T/F
true
what is an alternative somatostatin analogue used? what subtype does it bind to?
68Ga-dotatate
bings to subtype 2
why 68Ga PET scans?
- scans can be completed in 2 hrs
- radiation dose is less with 68Ga
