DR.SHARIQ A SHAH RADIODIAGNOSIS SKIMS SRINAGAR

1. THYROID IMAGING
MODERATOR: DR NASEER AHMAD CHOH
SR RESIDENT INCHARGE: DR TEHLEEL ALTAF
PRESENTER: DR SHARIQ AHMAD SHAH

2. OVERVIEW
• Anatomy and embryology
• Imaging modalities
• Diffuse thyroid disease
• Evaluation of a thyroid nodule
• Recent developments

3. ANATOMY OF THYROID
SIZE:
NEWBORN: 18-20 mm long
8-9 mm AP
ADULTS: 4-6 cm long
13- 18 mm AP
isthmus :4-6 mm
VOLUME:
19.6 ml males
18.6 ml females

5. EMBRYOLOGY
• Develops from median and lateral anlages.
• Median anlage: arises in the middle of oropharynx at 4th
to 5th gestation age , gives rise to follicular tissue.
• Lateral anlage: arise from ultimobrachial bodies
(derivatives of fourth and fifth branchial pouches), gives
rise to parafollicular c cells.
• Fusion occurs by tenth week forming bilobed gland

6. IMAGING MODALITIES
• X RAY
• USG
• RADIONUCLIDE IMAGING
• CT / MRI

7. X ray
• Enlargement
• Tracheal shift or narrowing
• calcifications
• Retrosternal extension
• Bone destruction
• Pulmonary metastasis

8. Nuclear scintigraphy
• Agents used are I-123, I-131, TC-99
• Done with a gamma scintillation camera
• Normal gland shows homogenous
radionuclide uptake and distribution

9. INDICATIONS
• Assessment of anatomy
• Assessment of function
• Post operative assessment
• Detection of nodule – hot or cold or warm
• Detection of functional metastatic tissue in known
case of thyroid ca.
• Detection of retrosternal goitre.

10. CONTRAINDICATIONS
• Pregnancy
• Hypersensitivity to iodine
• Discard breast milk for 26 hrs after injection

11. PREPARATION
• Stop antithyroid drugs 2 days before.
• Stop thyroid hormones 1 week before.
• Avoid iodinated contrast 4 weeks before.
• Stop iodine rich foods ( fish , cauliflower) a week
before.
• Done after 4 hr fasting.

12. Normal thyroid scan

13. Diffuse toxic goitre

15. DIFFERENTIAL DIAGNOSIS
COLD NODULE
(8-25% chances of malignancy)
• Thyroiditis
• Cyst
• Fibrosis
• Non functioning
adenoma
• Multinodular goitre
• Malignancy
HOT NODULE
(Malignancy rare)
• Functioning
adenoma
• Thyroiditis

16. USG
• First choice of evaluation
• Acessible, inexpensive and non invasive
• High spatial resolution- 0.5 to 1 mm
• Size and volume measurements.
• Doppler USG ( PSV of major thyroid A = 20-40cm
/s and intraparenchymal arteries= 15-30cm/s)

18. Congenital anomalies
• Hypoplasia/aplasia
• Ectopia
• Thyroglossal cyst

19. Diffuse thyroid disease
• Thyroiditis
Acute suppurative
Sub acute granulomatous (De Quervans)
Chronic lymphocytic ( Hashimoto)
Invasive fibrous throiditis (Riedels)
• Graves disease

20. Sub acute thyroiditis

21. Hashimoto - micronodularity

22. Hasimoto- coarse septation

23. Graves disease

24. Invasive fibrous ( Riedel’s thyroiditis)

25. EVALUATION OF THYROID NODULE
• NODULE: a discrete lesion that is
radiologically distinct from sorrounding
parenchyma.
• Some Palpable lesions may not be
radiologically distinct….not considered as
nodule
• Non-palpable nodules detected on imaging
studies --- incidentalomas

26. • Prevalence
• Incidence of malignancy : 9-13 %

29. • Generally only nodules > 1 cm should be
evaluated.
• Long term studies showed no difference in
outcome between patients with biopsy proven
carcinoma < 1 cm undergoing thyroidectomy
and those with no surgical intervention.
( Ito et al, world j surg 2010;34;28-35)

31. Serum TSH
• Serum TSH should be measured during initial evaluation
• If serum TSH is subnormal, a radionuclide scan should
be performed.
• If serum TSH is normal or elevated, a radionuclide scan
should not be performed as the initial imaging
modality.
Serum thyroglobulin measurement
• Routine measurement of serum Tg is not recommended.
( revised ATA 2015)

32. TSH and Radionuclide scan
• A higher TSH level , even within upper part of
refrence range is associated with increased risk of
malignancy in a thyroid nodule
• If TSH is low, risk of malignancy depends on tracer
uptake in scan
Hot nodule : rarely harbours malignancy, no
need for cytology.
Cold nodule: non functioning

33. USG

34. SUSPICIOUS NODULE
1. Taller than wide shape
2. Spiculated or irregular margins .
3. Markedly hypoechoic nodule.
4. Predominant solid composition.
5. Microcalcification in a predominantly solid nodule (3 fold
risk).
6. Macrocalcification in a solid nodule ( 2 fold risk)
7. Absence of halo.
8. Intranodular vascularity.

36. AMERICAN THYROID ASSOCIATION
NODULE GUIDELINES , JANUARY 2016.
•

38. HIGH HIGH
INTDD LOW
VERY LOW

39. Thyroid nodule evaluation and
management algorithm

40. Recommendations for initial follow up
of nodules with
BENIGN FNAC

41. 1. Nodules with high suspicion US pattern:
repeat US and USG guided FNAC within
12 months.
2.Nodules with low to intermediate suspicion US
pattern:
repeat US at 12 months
rapid growth or development of new
suspicious features repeat FNAC

42. 3. Nodules with very low suspicion:
utility of surveillance not known
4. If a nodule has undergone repeat FNAC with a
second benign cytology
no need to follow up with US

43. Follow up for nodules that do not
meet FNAC criteria

44. high suspicion us pattern repeat us in 6-12
months
low or intermediate suspicion us
pattern
repeat us at 12- 24
months
>1 cm nodules with very low
suspicion pattern
repeat us at > 24
months
< 1 cm nodules with very low
suspicion us pattern
no need of follow up

45. CROSS SECTIONAL IMAGING
• Important adjunctive anatomic information.
• Better delineation of lesion within thyroid.
• Detection of lymph node metastasis.
• Extension of disease to adjacent tissues of neck.
• Assess paraspinal muscle, esophageal, tracheal,
jugular vein invasion.

46. CT SCAN
• On NCCT thyroid appears as two wedge
shaped structures of homogenous attenuation
with density of 80- 100 HU because of iodine
content
• Enhances homogenously on iv contrast.
• Contrast interferes with radionuclide scan. so
scan should be performed either before CT or
6 weeks after it.

47. NCCT CECT

48. GOITRE

49. MRI
• Dedicated surface coils centered over thyroid.
• T1 : thyroid shows homogenous signal intensity
slightly greater than that of neck muscles.
• T2: gland is hyperintense relative to neck muscles
• Gadolinium contrast can be administered.
• Gadolinium does not interfere with iodine uptake
and organification, so can be used in conjunction
with scintigraphy.

50. T1W T2W

51. RECENT DEVELOPMENTS

52. PERFUSION CT
• Measures temporal changes in tissue density after
iv contrast.
• Quantifies abnormal vasculature within tumours,
thus allowing assessment of tumour agressiveness.
• Benign tumours have been found to show low BF
and MTT compared to malignant tissue.

53. DIFFUSION WEIGHTED MRI:
• Performed with the aim of differentiating
malignant from benign lesions.
• This technique evaluates rate of microscopic
water diffusion in tissues.
• All benign nodules have higher mean ADC value
than malignant nodules.

54. CONTRAST ENHANCED ULTRASOUND
• Enhancement pattern is recognised.
• Ring enhancement correlates with benign
lesions while heterogenous enhancement
correlates with malignant lesions.

55. COLLOID
CYSTIC PAPILLARY CA

56. ELASTOGRAPHY
• Obtains information about tissue stiffness non
invasively.
• Elastography score (ES) is assigned based on colour
pattern of lesion relative to sorrounding tissue.
• Red ( soft tissue), green ( intermediate degree of
stiffness), blue ( anelastic tissue).
• An ES of 4-5 is highly predictive of malignancy
(sensitivity 94%).

57. ELASTOGRAM PATTERNS
• PATTERN 1: Whole nodule elastic
• PATTERN 2: Most part elastic, inconsistent
inelastic areas
• PATTERN 3: Constant portions of anelastic areas
• PATTERN 4: Uniformly anelastic

58. BENIGN NOD
HYPERPLASIA
PAPILLARY CA

59. PET SCAN
• Used in follow up of patients with thyroid cancer due
to incresed glucose metabolism by malignant
tumours
• May be useful in tumours which don’t concentrate
iodine.
• In patients with raised thyroglobulin levels after
thyroidectomy, whole body scans are obtained to
identify regions of FDG uptake.

60. MAGNETIC RESONANCE
SPECTROSCOPY

61. OPTICAL COHERENCE TOMOGRAPHY

62. Thyriod ultrasound reporting lexicon--
TIRADS

65. Refrences
1. Carol rumack, diagnostic ultrasound 4e
2. David sutton,text book or radiology & imaging
3. Journal am coll radiol 2015;12:1272-1279
4. Open journal of radiology,2013,3 103-107
5. Radiology;vol 260:number 3-september 2011
6. Radiographics 2014;34:276-293

66. THANKS