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Thyroid NM Flashcards

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1
Q

Thyroid location

A

Level of II and III tracheal rings
4-5 cm by 1.5-2 cm

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2
Q

Thyroid weight

A

6-20 g

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3
Q

Pyramidal lobe

A

At surgery 80%
Remnant of thyroglossal duct
Can hypertrophy after thyroid resection

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4
Q

C cells = parafollicular cells

A

From neural crest
1% of cell population
Secrete Calcitonin in response to Calcium elevation
Express somatostatin receptors, Calcitonin generated peptid, gastrin releasing peptide
Medullary thyroid carcinoma
Independent of TSH
Inable to concentrate iodine

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5
Q

Nontoxic multinodular goiter

A

Increased thyroid hormone production
Only nodules >1 cm should be evaluated or <1 cm if malignant nature
Non palpable nodules ==same risk of malignancy as US confirmed palpable same size
Areas of iodine def - - goiter
4-17% fulfill criteria of malignant change, but majority is not malignant
Therapy with I131 to avoid surgery
100 microCi per g of thyroid tissue

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6
Q

Toxic Adenoma = Plummer Disease

A

TSH receptor mutation - - receptor is always activated - - rest of gland rest
Treatment with I131 in the phase of דיכוי - - kill adenomatous cells
Fixed max activity 16 mCi
Risk - genetic, female

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7
Q

Graves disease

A

AB to TSH receptor
60-80% of thyrotoxicosis
High iodine intake
Women, 20-50

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8
Q

Graves disease US

A

Diffusely enlarged
Increased vascularity on Doppler - - thyroid inferno
vs Hashimoto (normal blood flow)

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9
Q

Graves disease treatment

A

Antithyroid drugs = PTU, methimazole - - bone marrow tox, liver tox, relapse
Radioiodine therapy
Thyroidectomy when large goiter - - bleeding, laryngeal edema, hypopara, damage of recurrent laryngeal nerve

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10
Q

Graves disease Radionuclide treatment

A

I131 - - progressive destruction by beta, highly effective, cure rate 100%
Radiation thyroiditis 1-2 weeks after - - pain in anterior cervical region, thyrotoxic crisis (cytolysis)
Persistent hyperthyroidism - - second dose 8-12 months later
Fixed dose 5, 10, 15 mCi
Can conceive 6 months after
Use steroids if Ophtalmopathy

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11
Q

Hashimoto thyroiditis

A

Most common autoimmune disease, endocrine disorder, cause of hypothyroidism
Chronic inflammation
Enlarged, lymphocytic infiltration of thyroid, hypothyroidism
Primary ass with autoimmune disease

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12
Q

Hashimoto thyroiditis US

A

Hypoecho
Ground glass
Pseudonodules = bag of marbles
Tiny cystic lesions = Swiss cheese - - 2-3 mm
Fibrosis - - septa

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13
Q

Other forms of thyroiditis

A

Infectious (not viral)
De Quervain = subacute - - viral - - release of preformed thyroid hormone - - hypoecho to one lobe or a portion of lobe - - painful, palpable
Autoimmune
Riedels = chronic sclerosing thyroiditis - - overgrowth of connective tissue
Postpartum
Amiodarone

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14
Q

Risk for malignancy US

A

Microcalcification
Irregular or microlobulated margins
Hypoecho
Taller-than-wide
Hypervascular

Combi of at least 2

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15
Q

Tc pert

A

Beta and gamma, 140 keV, 6h
Iodomimetic
Transport through Na/I symporter, no organification
Max accumulation 15-20 min after IV, plateau 30 min
Image not later than after 30 min
1-10 mCi
5 min or 100000-200000 counts
High dose, high count, no preparation, lower radiation exposure
Nursing in 12-24h

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16
Q

I123

A

Pure gamma, 159 keV, 13h
Higher specificity and persistence of accumulation due to organification
Higher resolution, better visualisation of retrosternal, children, in case of low thyroid uptake
3-4h after PO 100-400 microCi
10 min or 50000-100000 counts
Breast feeding in 48 h

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17
Q

I131

A

Beta and gamma 364 keV 8 days
Limited to uptake test, monitoring of DTC treatment, ectopic thyroid (retrosternal, lingual, struma ovarii), dosimetric pretreatment evaluation
High gamma–no sternal attenuation
24h after PO
10 min or >50000 counts

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18
Q

Pitfalls

A

Medication, CT contrast - - no uptake
Acute/subacute thyroiditis
Therapy with TSH suppressive doses of HRT
Hyperthyroidism (too much hormones)
Local contamination
Esophageal activity - - drink water

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19
Q

Nodules

A

Hot = hyperfunctioning - - almost never malignant
Cold = hypofunctioning - - 3-15% malignant
Indeterminate - - 3-15% malignant
Predictive value is low, esp if nodule <1 cm

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20
Q

RAIU

A

I131 PO 30-100 microCi
Measure at 4h and 24h
24h <20% - - no therapy

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21
Q

Radionuclide Therapy

A

I131, beta, 2.4 mm range in tissue
Cellular necrosis, inflammation, follicles destruction, fibrosis
Goal - to achieve hypothyroidism and reduce volume

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22
Q

Radionuclide therapy of benign
preparation

A

2 weeks low-iodine diet
4 weeks CeCT
3 months Amiodarone (definitive treatment for Amiodarone-induced thyrotoxicosis
3 weeks Lugol, topical iodine, Li (can block release from thyroid)

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23
Q

Radionuclide therapy and
Elderly, heart disease, systemic illness

A

Pretreatment with thionamides (PTU, MTMZL) to avoid radiation induced thyroiditis
Stop 3-5 days before, resume 2-3 days after to prevent thyroid storm
Beta blockers - no need to stop

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24
Q

Radionuclide therapy and pregnancy

A

Abs Contra
Fetal thyroid concentrates iodine by week 10-13
Stop breastfeeding and no resume

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25
Radionuclide therapy and iodine sensitivity
Safe
26
Surgery benign
Tracheal narrowing <1 cm - - steroids <5-6 mm - - surgery 80 g gland - - surgery
27
Induced hypothyroidism
2-3 months after radioiodide therapy Levothyroxine as soon as TSH elevation is detected
28
Radioiodide therapy side effects
Inflammation with edema Transitory hyperthyroidism - - steroids and beta blockers to prevent Rare - - autoimmune thyroid disease 2-6 months after Ophtalmopathy - - stop smoking, take steroids, start HRT after treatment
29
Efficacy of radioiodine treatment
Volume reduction to 30-40% within 1 year Further reduction to 50-60% next year Within 2-3 years hypothyroidism
30
Malignant thyroid disease
Thyroid nodule - - 4-5% of all thyroid nodules Women Sporadic/familial Differentiated TC: papillary and follicular Anaplastic TC = Stage IV Medullary TC
31
Thyroid cancer M
Lung (PTC and young) Bone (FTC and old) Skin Brain
32
Associated disease with Thyroid cancer
Gardner syndrome Cowden syndrom - - FTC RET oncogene Hashimoto - - thyroid lymphoma
33
PET indication for thyroid cancer
DTC Post Thyroidectomy Eleveted Thyroglobulin Negative I131 WBS Tumor become iodine insensitive - - flip-flop - - FDG avid
34
ATC
Stage IV IVB unresectable Rapid grow - - big firm nodule, recently developed, 3-15 cm Dysphonia Dysphagia, dyspnea 30-40% regional LN and vocal cord paralysis Surgery, chemo, EBRT Very poor prognosis Death from airway obstruction
35
Dedifferentiation of DTC
44% of ATC had previous or concurrent DTC
36
ATC mutations
BRAF V600E RAS + BRAF - - resistance to vemurafenib
37
MTC
C-cells Sporadic 75% MEN2 - - 100% MTC, 50% pheo, 20-30% PHP Hereditary - - RET mutation Only 1% low diff - - do not produce Calcitonin - - marker Well-diff
38
Elevated Calcitonin
Renal failure Autoimmune disease Hyperpara FTC Net of Pancreas Prostate ca Lung ca
39
Calcitonin in stimulation test with calcium, pentagastrin
Do not increase
40
MTC treatment
Surgery I131-MIBG Y90- and Lu177 DOTA - TOC/NOC/TATE Advanced/recurrent/metastatic - - TKI
41
ATA guideline FNA
>1 cm with high suspicion >1 cm with intermediate suspicion >1.5 cm with low suspicion >2 cm with very low suspicion (spongiform)
42
Cytology
Thy1 - nondiagnostic aspirate Thy2 - benign Thy3 - cytology is not diagnostic Thy4 - suspicious for malignant Thy5 - malignant
43
DTC NM
Espression of NIS gene reduced - - cold nodule - - can be benign nonfunctioning adenoma Thyroid scan low specificity FDG - - 4% increased focal uptake in thyroid - - incidentaloma - - 20% malignant
44
ATC NM
High levels of GLUT1 and GLUT3-- FDG the best US, CT, MRI for defining local extent
45
MTC NM
Neuroendocrine features Express receptors for somatostatin - - MIBG image and therapy, FDOPA, radiolabeled somatostatin analogs therapy FDG is suboptimal Normal Calcitonin - - excellent response - - 10 year survival 100% Useless imaging if Calcitonin <150 pg/mL
46
Calcitonin >150 pg/mL
Neck US LN recurrence most common
47
Calcitonin >500 pg/mL
CT, MRI, PET
48
Thyroid cancer T
49
Thyroid cancer N
VI, VII II-V retropharyngeal
50
Thyroid cancer M0
<55 years - - Stage I
51
Thyroid cancer M1
<55 years - - Stage II
52
Thyroid cancer surgery
FTC - - solitary nodule PTC - multifocal growth - - total Thyroidectomy - - vocal cords palsy, permanent hypopara PTC in single small nodule - - lobectomy + neck US Central LN dissection
53
Adjuvant ablation of postsurgical remnant
DTC - - to eliminate any residual, macroscopically normal thyroid left TSH stimulation > 30 microIU/mL: stop L-thyroxine for 4-6 weeks or rhTSH 0.9 mg IM 2 days I131 ablation 30-100 mCi WBS 4-7 days after
54
No benefit from ablation
Tumor <1.5 cm LN negative Unifocal microcarcinoma T1a
55
Ablation preparation
2 weeks low-iodine diet Stop L thyroxine for 4-6 weeks to TSH > 30 microIU/mL or rhTSH Urine iodine content Iodine / creatinine ratio <250 microg/g NPO from midnight
56
LN suspicious
FNA, Tg <1 cm - - I131 therapy Bigger - - surgery, radioiodine therapy
57
Recurrent DTC
Poorly diff - - do not concentrate iod FDG TKI sorafenib and Lenvatinib
58
Thyroid stunning
Prior diagnostic I131 - - non ablative up to 10 Gy - - reduced NIS expression in response to irradiation induced DNA damage - - 50% reduced ability to concentrate and store radioiodide - - reduced uptake If I131 as preablation assessment - - no more than 2 mCi and ablation within 48-72 h
59
I123 used as preablation assessment
Auger electrons No stunning effect
60
15% of DTC dedifferentiate
After several courses of I131 Retinoic acid Selumetinib Reinduce iodine uptake ability
61
DTC +MTS, non iodine avid, rapidly grow
Only Doxorubicin
62
Radioiodine ablation Relative Contra
Bone marrow depression Impaired pulmonary function - - significant accumulation Intracranial DTC lesion - - oedema and compression Functional deficit of salivary gland
63
Radioiodine ablation Side effects
Hypothyroidism 2-3 weeks after reintroduction of L-thyroxine Nausea, gastric pain - - PPI Sialoadenitis - - fluids and lemon juice Loss or change of taste Steroid to prevent radiation induced inflammation Transient impairment of male gonadal function
64
Second malignancy or leukemia
After repeat ablation + EBRT >500 mCi
65
Exposure to I131 affects outcome of pregnancy and offspring
No evidence
66
Diffuse lung MTS
Radiation fibrosis if 150 mCi at short intervals <6 months <80 mCi after 48h
67
Levothyroxine treatment PTC, FTC Post-op
To correct post op hypothyroidism To suppress secretion of TSH Young - - higher dose T3 and T4 should be normal No adverse effects on bone maturation, final height, pubertal development Not to take the morning before blood test - - increase T4 by 25% Aim - - TSH 0.1-0.5 microIU/mL
68
Iodine daily requirement
150 microg Bread, milk, seafood
69
24h uptake <10-15%
Stimulation with recombinant human TSH 0.3 mg for MNG 0.9 mg for DTC
70
Measure radioiodine dose for MNG
Thyroid mass * 3.7 MBq = initial activity Uptake 30% - - thyroid mass *3.7 : 0.3
71
Most common of all thyroid disease
MNG
72
Most common cause of hyperthyroidism
Graves Toxic Adenoma
73
Graves disease risk
Infections Iodine intake Smoking Psychic stress
74
Graves disease lab
Elevated bilirubin, liver enzymes, ferritin Microcytic anemia. Thrombocytopenia
75
Thyroid scintigraphy Indication
All cases of thyroid nodule MNG if TSH is low Ectopic thyroid Retrosternal goiter
76
C cells vs follicular cells
Junction of Upper 1/3 and lower 2/3, along central axis Functional independence from TSH Inability to concentrate and retain iodide Production and secretion of Calcitonin
77
Ablation Indication
DTC moderate - high risk No role - in ATC and poorly diff TC - - do not concentrate iodine
78
Benefits from adjuvant ablation
Decrease recurrence Early detection Sensitive I131 WBS Any subsequent I131 therapy will be more effective
79
Ablation successful
90% if uptake in residue <2% - - residual mass <2g 2/3 if uptake in residue >2% - - residual mass >2g
80
T3 three times per day
Tachycardia
81
DTC follow up after primary treatment 6-12 m
Serum Tg - - 20-25% anti Tg autoAB interfere - - not reliable Undetectable under L-thyroxine suppressive therapy - - confirm with TSH stimulation test - - can be avoided if basal Tg <0.1 ng/mL, but reserved for gray zone 0.1-1 ng/mL Cutoff Tg 2 ng/mL (FDA 2.5 ng/mL) I131 WBS Neck US
82
Bulkier recurrence limited to LN
Surgery
83
No uptake on post treatment WBS
Stop treatment with I131
84
Uptake %
Graves 50-80% MNG 20-30% Normal 4h 4-15% Normal 24h 10-30%
85
Tc pert high radiation dose to thyroid
Beta High gamma Long T1/2 Contaminants I124 and I125 increase radiation dose
86
Cold nodule
10-30% risk of malignancy
87
Nodule hot on Tc pert, but cold on I123
2-3%
88
Uptake dd thyroiditis vs Graves
Thyroiditis - - abnormally low Graves - - abnormally high
89
Thyroid whole body scan biodistribution
Stomach, urinary clearance Remnant thyroid or MTS
90
1 weeks after administration of 100 mCi I131
Residual tissue in thyroid bed Local MTS under ablation Physiological liver uptake No uptake in stomach and small bowel - - >48h
91
FDG thyroid cancer
ATC MTC Hurtle cell
92
FDG diffuse bilateral uptake
Thyroiditis Graves Hypothyroidism

NM By Myself (25 decks)

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