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Role of imaging in management of thyroid nodules Abstract ID – IRIA - 1240.

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Presentation on theme: "Role of imaging in management of thyroid nodules Abstract ID – IRIA - 1240."— Presentation transcript:

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 131/123 I scintigraphy Ga68 DOTA scintigraphy PET-CT

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

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

5 Specific features Microcalcifications Markedly hypoechoic Taller than wide in transverse plane Extension beyond thyroid margin Cervical lymph node metastasis Less specific features No halo around nodule Ill-defined or irregular margin Solid Increased central vascularity US features of malignant nodules 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 % Radiographics May-Jun;27(3): Coarse calcifications MC in medullary carcinomas May coexist with microcalcifications in papillary cancers Inspissated colloid calcifications May mimic microcalcifications Distinguished by ring down/reverberation artefact Peripheral calcification Most common in MNG Break in peripheral calcification – malignant change in an underlying multinodular goitre

7 2. Margins, contour and shape Hypoechoic halo highly suggestive of benignity pseudocapsule of fibrous connective tissue or compressed thyroid parenchyma specificity 95% Radiographics May-Jun;27(3): Shape taller than wide 93% specificity for malignancy 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 Contour Smooth and rounded Irregular/jagged edges

8 3. Echogenicity of the nodule Malignant nodules are solid and hypoechoic Sensitivity 87% but low specificity 15-27% Marked hypoechogenicity Darker than strap muscle Specificity 94% Radiographics May-Jun;27(3): 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

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) J Clin Endocrinol Metab May;94(5): Vascular heteroechoic non- expansile, non- encapsulated nodules with peripheral halo (colloid type II) Isoechoic or heteroechoic, non- encapsulated, expansile vascular nodules (colloid type III) TIRADS 3 Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral vascularity <5% risk of malignancy

12 J Clin Endocrinol Metab May;94(5): TIRADS 4 & 5 Based on five features: 1.solid component 2.markedly hypoechoic nodule 3.microlobulations or irregular margins 4.microcalcifications 5.taller-than-wider shape TIRADS 4a - one suspicious feature TIRADS 4b - two suspicious features TIRADS 4c suspicious features TIRADS 5 - all five suspicious features 4a % risk of malignancy 4b & 4c % risk of malignancy 5 - >80% risk of malignancy

13 Cystic component occurs in 13-26% Predominant cystic appearance is rare Can mimic benign cystic hyperplastic nodule RadioGraphics 2007; 27:847–865 Pitfalls on USG - 1. Cystic variant of papillary carcinoma 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

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 Case of thyroid lymphoma – markedly hypoechoic and diffusely enlarged thyroid gland in a 62 year old man Look for  Echogenicity – markedly hypoechoic  History  Microcalcifications

15 ELASTOGRAP HY Objective evaluation of tissue stiffness to differentiate between benign and malignant nodules Sensitivity – 96.3 %; Specificity – 96.2% Ultrasonography 2014; 33(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

16 CT & MRI Inferior to ultrasound in diagnosing thyroid cancer Main role is in staging Intravenous iodinated contrast agents interfere with the 131/123 I 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 Any palpable thyroid nodule if its not TIRADS 2 – FNAC should be done FNA C CT protocol Non-contrast Thin slice thickness – mm Axial, coronal & sagittal planes Neck & thorax (MC & AC – include liver)

17 Calcification CT preferred Retrosternal region Metastasis Mediastinal nodes Extent

18 Ga68 DOTA PET/CT 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 Indications whole body scan for distant metastases estimation of local residual thyroid post thyroidectomy follow-up for tumour recurrence Thyroid scintigraphy Cold – 85% of nodules are cold, hence not used to diagnose malignancy Medullary carcinoma

19 High negative predictive value Incidental focal uptake in thyroid  Specific USG features  80 % malignant FDG-PETImaging in distant metastases 131 I – treatment of functioning thyroid cancer & imaging of functioning metastases Ga68 DOTA PET/CT Bone scan / scintigraphy – bone metastases CT / MRI – if needed Cancer imaging.2008;8(1):57-59 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)

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

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