Endocrine GW

Question 1

Thyroid hormones

Answer 1

T3 triiodothyronine

T4 tetraiodothyronine

Question 2

What cells trap iodide in thyroid

Answer 2

Thyroid follicular cells trap iodide through the iodide pump

Question 3

Iodide is oxidized to form 1 of 2 molecules

Answer 3

MIT or DIT

Question 4

One MIT and one DIT molecule =

Answer 4

T3

Question 5

One DIT and one DIT molecule =

Answer 5

T4

Question 6

What does the anterior pituitary gland produce and secrete

Answer 6

TSH - thyroid stimulating hormone

Question 7

Hypothalamus produces and secretes what hormone

Answer 7

TRF - thyrotropin releasing factor

Question 8

Which RP can be used for but is not recommended for routine imaging

Answer 8

I131

Question 9

Indications for thyroid imaging

Answer 9

Relate gland structure to function
Evaluate size and nodules/masses
Identify ectopic tissue

Question 10

Thyroid RPs and doses

Answer 10

pertechnetate 2-10 mCi (imaging)

I123 0.1-0.2 (uptake)
- 0.2-0.6 (imaging)

I131 0.004-0.01 (uptake)
- 0.05 - 0.2 (imaging)

Question 11

Administration to imaging time for each RP for thyroid

Answer 11

Pertechnetate 15-30 minutes

I123 3-4 or 16-24 hours

I131 6-24 hours

Question 12

How long may a low iodine diet be recommended prior

Answer 12

3-10 days prior

Question 13

How to magnify views with pinhole collimator

Answer 13

Bring collimator closer to neck

Question 14

Most interfering drugs and procedures must be withheld

Answer 14

2-4 weeks

Thyroxine (thyroid med) 4-6 weeks

Antithyroid meds 2-8 days

Question 15

Which lobe of thyroid is larger

Answer 15

Right

Question 16

Nonfunctioning “cold” nodules means

Answer 16

Cancer
Cyst
Hematoma
Inflammatory conditions
Benign adenoma

Question 17

Hot nodules mean

Answer 17

Typically benign

Question 18

Thyroid uptake at 2-6 hours reflects what function

Answer 18

Iodide trapping and organification

Question 19

Iodide uptake is useful for

Answer 19

Hyperthyroidism who need i131 therapy
Organification defects
Thyroiditis

Question 20

Thyroid uptake and imaging prep

Answer 20

Fast from midnight the night before and for 2 hours after taking pill

Question 21

What distance is the uptake probe

Answer 21

25-30 cm

Question 22

Normal uptake values

Answer 22

4 hours: 6-18%

24 hours: 10-35%

Question 23

Factors that can increase uptake

Answer 23

Iodine deficiency
Pregnancy
Lithium
Rebound after stoping thyroid meds

Question 24

Factors that can cause decreased uptake

Answer 24

Renal failure, severe congestive heart failure
Excess iodine including recent contrast
Meds containing T4 and antithyroid meds

Question 25

Whole body thyroid imaging after thyroidectomy to identify residual tissue or areas of mets RP and dose

Answer 25

I131 1-10 mCi (controversial) 123 1-2 mCi (is being considered)

Question 26

Administration to imaging time for WB thyroid imaging

Answer 26

24 hours 48 optimal?

Question 27

TSH level must be _____ before WB thyroid residual post thyroidectomy imaging

Answer 27

Greater than 30-50 mU/L

Question 28

Parathyroid imaging is useful for

Answer 28

Hyperparathyroidism - excess PTH

Question 29

Excess PTH does what

Answer 29

Stimulates removal of calcium from bones and causes hypercalcemia in the blood

Question 30

Parathyroid imaging pt prep

Answer 30

None

Question 31

Parathyroid dual phase RP, dose, and technique

Answer 31

99mTc Sestamibi 5-25 mCi -Localizes in both thyroid and parathyroid but washes out of thyroid Early imaging (10 mins) And delayed imaging (1.5-2.5 hours)

Question 32

Parathyroid dual tracer RPs and where they localize

Answer 32

99m Tc pertechnetator OR i123 -localize in thyroid AND 99mTc sestamibi OR Tl201 - localizes in both thyroid and abnormal parathyroid

Question 33

Which RP is subtracted from which in dual tracer parathyroid imaging

Answer 33

The ones that localize in thyroid or subtracted from the ones that localize in abnormal parathyroid

Question 34

What pathology is often coincided with hyperparathyroidism

Answer 34

Thyroid disease - can cause false positive and non uniform uptake

Question 35

Which parathyroid technique has more advantages

Answer 35

Dual phase

Question 36

Which RP should go first in dual tracer parathyroid

Answer 36

Either one but the advantage to tech going first is that the pt doesn’t have to remain in one position as long as

Question 37

Disadvantage of tech/Tl201 dual tracer parathyroid imaging

Answer 37

Downscatter

Question 38

Adrenal gland cortex produces

Answer 38

Steroid hormones -cholesterol is a building block

Question 39

Adrenal medulla produces what hormone

Answer 39

Catecholamines

Question 40

RP and dose used to image adrenal medulla

Answer 40

I123 mIBG 10 mCi I131 mIBG 0.5 mCi

Question 41

RP used to image adrenal cortex

Answer 41

I131 radiolabeled cholesterol

Question 42

Where is free iodine secreted

Answer 42

Urine

Question 43

Adrenal imaging acquisition

Answer 43

I131 - Imaged at 1, 3, and 7 days I123 - 24-48 hours *Image from vertex to pelvis

Question 44

Normal i123 or i131 mIBG uptake

Answer 44

Liver, spleen, heart Maybe salivary glands and bladder from free iodine

Question 45

Pt prep for adrenal imaging

Answer 45

Lugols solution 1 day prior and 6-7 days after administration

Question 46

Common antithyroid drugs

Answer 46

Propylthiouracil, methimazole (tapazole), carbimazole

Question 47

Common thyroid meds

Answer 47

Synthroid, cytomel, levothyroxine