Endocrine

Question 1

Rationale for parathyroid imaging

Answer 1

Hyperparathyroidism, localization of parathyroid adenomas

Question 2

Parathyroid contraindications

Answer 2

Pregnant, breast feeding, recent nuc med study, inability to stay still

Question 3

Parathyroid pt prep

Answer 3

No special prep, just focused Hx and labs

Serum calcium and PTH levels measured 1 month prior

Question 4

Parathyroid RP and doses

Answer 4

99mTc Sestamibi 20-30mCi

99mTc sodium pertechnetate 2-10mCi

I123 Sodium iodide 200-600 uCi oral

Question 5

Parathyroid RP injection to imaging time

Answer 5

10 mins with Sestamibi

30 mins with pertechnetate

4 hours with I123

Question 6

Parathyroid collimator

Answer 6

LEHR and pinhole

Question 7

3 ways parathyroid imaging protocols

Answer 7

Dual phase Sestamibi

Dual isotope with tech and Sestamibi

Dual isotope with i123 and sestamibi

Question 8

Parathyroid dual phase protocol

Answer 8

-Inject Sestamibi
-Take ANT images 10-30 mins after inj
-Wait 1.5-2.5 hours and take delay ANT images
-take spect or pinhole images in ANT and ANT OBL

Question 9

Parathyroid dual isotope tech/Sestamibi protocol

Answer 9

-Inject either one first but wait 10 mins with Sestamibi and 30 mins with tech
-obtain images of head and neck after appropriate wait times
*can immediately inject next RP after images are taken of first RP

Question 10

Parathyroid dual isotope i123/sestamibi

Answer 10

*administer i123 FIRST and wait 4 hours
-take ANT images
-inject sestamibi and wait 10 mins
-take ANT images

Question 11

Parathyroid subtraction technique

Answer 11

For tech/sestamibi: subtract the tech images from the sestamibi images

For i123/sestamibi: subtract the i123 images from the sestamibi images

Question 12

What reconstruction method is recommended for spect parathyroid

Answer 12

Iterative reconstruction

Question 13

How is iodine/iodide localized

Answer 13

Accumulated in thyroid follicular cells by an active transport mechanism (trapping) and then oxidized and bound to tyrosyl residues on thyroglobulin (organification)

Question 14

Indications of thyroid imaging

Answer 14

-Differentiation of hyperthyroidism (graves vs toxic nodular goiter)
-Detection and evaluation of hyperthyroidism and hypothyroidism
-localization of ectopic thyroid tissue
-exaltation of neck mass
-differentiation of thyroiditis

Question 15

Indications of thyroid uptake

Answer 15

-determination of i131 therapy dose
-differentiation of subacute or painless thyroiditis and factitious hyperthyroidism from graves
-confirmation of hyperthyroidism due to Graves’ disease

Question 16

Contraindications to thyroid uptake and imaging

Answer 16

Pregnant, breast feeding, recent nuc med study

Pt not properly prepped

Question 17

Pt prep for thyroid uptake and imaging

Answer 17

AVOID:
-thyroid hormones and antithyroid drugs
-iodine containing medications
-food rich in iodine
-large meals for 2 hours prior and 2 hours post administration

Question 18

How long to D/C contraindicated meds for thyroid uptake and imaging

Answer 18

-Antithyroid drugs withheld 2-4 days
-T4 therapy withheld 4-6 weeks
-T3 therapy withheld 2 weeks

-iodinated contrast within 3 weeks
-Amiodarone d/c for 6 months
-Betadine within 2-4 weeks

Question 19

Thyroid uptake and imaging RPs

Answer 19

I123 sodium iodide 100-300 uCi

99mTc pertechnetate 2-10 mCi

I131 sodium iodide 0.004 - 0.01 mCi

Question 20

Collimator for thyroid imaging

Answer 20

Pinhole

Question 21

Thyroid administration to uptake time

Answer 21

Tech: immediately

I123: 2-6 and 18-24 hrs

I131: 2-6 and 18-24 hrs

Question 22

Thyroid administration to imaging time

Answer 22

Tech: 15-30 minutes

I123: 3-4 hours

I131: not recommended for imaging, uptake only

Question 23

Which RP is not recommended for thyroid imaging, uptake only

Answer 23

I131

Question 24

Thyroid imaging views

Answer 24

ANT
LAO, RAO
ANT with marker

Question 25

Where to put radioactive markers for thyroid imaging

Answer 25

Sternal notch and thyroid cartilage On nodules

Question 26

Where/how to use uptake probe

Answer 26

25-30 cm and take counts for 1 min Neck Thigh Phantom Room background

Question 27

Collimator for WB thyroid imaging

Answer 27

LEAP

Question 28

Percent Radioiodine uptake (RAIU) formula

Answer 28

Neck counts - thigh counts ______________________________ Phantom counts - background counts

Question 29

I131 is no longer useful for:

Answer 29

Imaging the thyroid gland, as a diagnostic tracer

Question 30

I131 is useful for

Answer 30

WB imaging after a thyroidectomy, therapy for hyperthyroidism, thyroid remnant ablation, and thyroid cancer

Question 31

I131 T1/2 and energy

Answer 31

T1/2: 8.01 days 363 keV

Question 32

I131 emission

Answer 32

Beta and gamma

Question 33

I131 produced by

Answer 33

Fission/nuclear reactor

Question 34

I123 decays by

Answer 34

Electron capture

Question 35

I123 T1/2 and energy

Answer 35

T1/2: 13 hr 159 keV

Question 36

I123 uses

Answer 36

Thyroid imaging + uptake Calculating an uptake only, pretreatment diagnostic mets survey for thyroid cancer

Question 37

Normal values for 4 hr uptake

Answer 37

6-18%

Question 38

Normal values for 24 hr uptake

Answer 38

10-35%

Question 39

In parathyroid study, tech and i123 go where? Ate sestamibi and thallium go where? And which is subtracted from which?

Answer 39

1. Tech and i123 go to thyroid 2. Mibi and thallium go to thyroid and abnormal parathyroid (but wash out of thyroid 3. Subtract 1-2