1. Role of imaging in management of thyroid nodules
Abstract ID – IRIA

2. Investigations Ultrasound – Best modality USG guided FNAC CT MRI
Technetium-99m pertechnetate or 131/123I scintigraphy
Ga68 DOTA scintigraphy
PET-CT

3. USG descriptors of thyroid nodules
Echogenicity
Hyperechoic (> thyroid), Isoechoic (= thyroid), Hypoechoic (< strap muscles)
Taller > wide
Shape
Microcalcification = / < 1mm
Calcifications
Margin
Circumscribed, Microlobulated, Irregular
Vascularity
Central or peripheral
Composition
Solid, Cystic, Mixed
Radiology. 2011 Sep;260(3):892-9

4. US features of benign nodules
Uniform halo around nodule
Enlarged thyroid with
multiple nodules
Predominantly cystic Avascular
Peri-nodular or spoke-and-wheel like appearance of vessels
Radiographics May-Jun;27(3):847-60

5. Less specific features
US features of malignant nodules
Specific features
Less specific features
Microcalcifications
Markedly hypoechoic
Taller than wide in transverse plane
Extension beyond thyroid margin
Cervical lymph node metastasis
No halo around nodule
Ill-defined or irregular margin
Solid
Increased central vascularity
Radiographics May-Jun;27(3):847-60

6. 1. Calcifications Microcalcifications
Psammoma bodies
Common in papillary carcinoma
Specificity 86%–95%
Positive Predictive Value: 42 – 94 %
Inspissated colloid calcifications
May mimic microcalcifications
Distinguished by ring down/reverberation artefact
Coarse calcifications
MC in medullary carcinomas
May coexist with microcalcifications in papillary cancers
Peripheral calcification
Most common in MNG
Break in peripheral
calcification – malignant
change in an underlying
multinodular goitre
Radiographics May-Jun;27(3):847-60

7. 2. Margins, contour and shape
Hypoechoic halo
highly suggestive of benignity
pseudocapsule of fibrous
connective tissue or
compressed thyroid parenchyma
specificity 95%
Ill-defined margins
> 50% of its border is not clearly demarcated
indicate infiltration of adjacent parenchyma
sensitivity: 53%– 89% and specificity 7%–97%
Hence frank invasion beyond the capsule has to be demonstrated on HPE
Shape
taller than wide
93% specificity for malignancy
Contour
Smooth and rounded
Irregular/jagged edges
Radiographics May-Jun;27(3):847-60

8. 3. Echogenicity of the nodule
4. Vascularity
Marked intrinsic hypervascularity
Flow in the central part of tumour > surrounding thyroid parenchyma
Benign nodules
Perinodular vascularity – 25% of circumference
Complete avascularity is a more useful sign
These features are more useful in selecting a nodule for FNAC in multinodular goitre
Malignant nodules are solid and hypoechoic
Sensitivity 87% but low specificity %
Marked hypoechogenicity
Darker than strap muscle
Specificity 94%
Radiographics May-Jun;27(3):847-60

9. 5. Local invasion and lymph node metastasis
Features of nodal involvement
Rounded bulging shape
Increased size
Replaced fatty hilum
Irregular margins
Heterogeneous echotexture
Calcifications / Cystic areas
Vascularity throughout the lymph node instead of normal central hilar vessels

10. TIRADS - Thyroid image reporting and data system
TIRADS 1 - normal thyroid gland
TIRADS 2 - benign lesions
TIRADS 3 - probably benign lesions 
TIRADS 4 - suspicious lesions (4a, 4b, and 4c with increasing risk of malignancy)
TIRADS 5 - probably malignant lesions (> 80% risk of malignancy)
TIRADS 6 - biopsy proven malignancy
J Clin Endocrinol Metab May;94(5):

11. TIRADS 2 – Colloid nodules - 0% risk of malignancy
Avascular anechoic lesion with echogenic specks (colloid type I)
Vascular heteroechoic non-expansile, non-encapsulated nodules with peripheral halo (colloid type II)
Isoechoic or heteroechoic, non-encapsulated, expansile vascular nodules (colloid type III)
Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral vascularity
<5% risk of malignancy
TIRADS 3
J Clin Endocrinol Metab May;94(5):

12. TIRADS 4 & 5 Based on five features: solid component
markedly hypoechoic nodule
microlobulations or irregular margins
microcalcifications
taller-than-wider shape
TIRADS 4a - one suspicious feature
TIRADS 4b - two suspicious features
TIRADS 4c - 3-4 suspicious features
TIRADS 5 - all five suspicious features
4a % risk of malignancy
4b & 4c % risk of malignancy
5 - >80% risk of malignancy
J Clin Endocrinol Metab May;94(5):

13. Pitfalls on USG - 1. Cystic variant of papillary carcinoma
Cystic component occurs in 13-26%
Predominant cystic appearance is rare
Can mimic benign cystic hyperplastic nodule
Look for
Solid components with vascularity
Solid excrescences protruding into the cyst
Angle of contact by the solid component with the cyst wall
Acute – malignancy
Obtuse – degenerating cyst (colloid)
Microcalcifications
RadioGraphics 2007; 27:847–865

14. 2. Diffusely infiltrative hypervascular tumour
This variant can be seen in papillary, follicular carcinomas and lymphoma
Mimics autoimmune conditions Ex. Graves / thyroiditis
De Quervain’s thyroiditis – hypoechoic nodule, may be taller than wide / may have microcalcification
Short duration of history of pain
Soft on Elastography
Look for
Echogenicity – markedly hypoechoic
History
Microcalcifications
Case of thyroid lymphoma – markedly hypoechoic and diffusely enlarged thyroid gland in a 62 year old man

15. ELASTOGRAPHY VTI – Virtual Touch Imaging
Objective evaluation of tissue stiffness to differentiate between benign and malignant nodules
Sensitivity – 96.3 %; Specificity – 96.2%
VTI – Virtual Touch Imaging
Reflects the elasticity of tissue with gray-scale image in the field of view (FOV)
Dark indicates hard tissue whereas the bright indicates soft tissue
VTQ – Virtual Touch Quantification
Range for shear wave velocity is 0–9 m/s (beyond this range displayed as “x.xxm/s”)
 The mean shear wave velocity of VTQ
malignant nodules – 3.88 ± 2.24 m/s
Benign nodules  ± 0.79 m/s
Ultrasonography 2014; 33(2): 75-82

16. FNAC CT & MRI CT protocol
Any palpable thyroid nodule if its not TIRADS 2 – FNAC should be done
CT & MRI
CT protocol
Non-contrast
Thin slice thickness – mm
Axial, coronal & sagittal planes
Neck & thorax (MC & AC – include liver)
Inferior to ultrasound in diagnosing thyroid cancer
Main role is in staging
Intravenous iodinated contrast agents interfere with the 131/123I uptake for at least 1–3 months
Advantage of MRI
avoids the use of iodinated contrast agents
Very specific in showing tracheal, oesophageal and recurrent laryngeal nerve invasion

17. CT preferred Calcification Retrosternal region Extent Metastasis
Mediastinal nodes

18. Ga68 DOTA PET/CT Thyroid scintigraphy
Somatostatin analogs labelled with Ga 68
High affinity for Somatostatin receptors
SSTR expressed – neurons & endocrine cells
Thyroid – medullary carcinoma
To localize an inconclusive nodule
Staging
Recurrence
Treatment response
Medullary
carcinoma
Thyroid scintigraphy
Indications
whole body scan for distant metastases
estimation of local residual thyroid post thyroidectomy
follow-up for tumour recurrence
Cold – 85% of nodules are cold, hence not used to diagnose malignancy

19. Imaging for post-op, pre-radiotherapy planning and surveillance
FDG-PET
Imaging in distant metastases
131I – treatment of functioning thyroid cancer & imaging of functioning metastases
Ga68 DOTA PET/CT
Bone scan / scintigraphy – bone metastases
CT / MRI – if needed
High negative predictive value
Incidental focal uptake in thyroid  Specific USG features  80 % malignant
Imaging for post-op, pre-radiotherapy planning and surveillance
To look for residual / recurrence of primary tumour & nodal involvement
Routinely done with ultrasound; CT / MRI – no significant role
Yearly ultrasound of the neck +/− FNA for surveillance of disease-free patients
PC/FC - normal thyroglobulin (Tg > 50 ng/mL – functioning metastases after complete ablation of thyroid tissue)
Cancer imaging.2008;8(1):57-59

20. Conclusion
Ultrasound plays a major role differentiating benign & malignant nodules
Specific features:
markedly reduced echogenicity
microcalcifications
taller than wide
local invasion
lymph node metastases
Histopathological examination – confirmatory
Recent advances – Elastography increases the positive predictive value when combined with conventional ultrasound