Thyroid Nodules: US Risk Stratification. Alex Tessnow, MD, FACE, ECNU University of Texas Southwestern Associate Professor of Medicine Dallas, Texas

Transcription

1 Thyroid Nodules: US Risk Stratification Alex Tessnow, MD, FACE, ECNU University of Texas Southwestern Associate Professor of Medicine Dallas, Texas

2 Which of the following is true? A. All echogenic foci represent microcalcifications B. Hypervascularity of any nodule is an independent risk factor for thyroid cancer C. A thin hypoechoic, regular halo surrounding an isoechoic nodule is generally suggestive of a low risk process D. In a multinodular thyroid gland the largest nodule is the most concerning for malignancy E. Spongiform nodules have an intermediate risk of malignancy

3 US Appearance of Nodules Composition (solid/cystic) Echogenicity (darkness on US) Margins Presence of calcifications Shape Vascularity

4 ATA 2015: Nodule Sonographic Pattern Risk of Malignancy High Suspicion 70-90% Intermediate Suspicion 10-20% Low Suspicion 5-10% Very low Suspicion <3% Benign <1% Haugen et al. Thyroid; October 2015 (epub)

5 Characteristics Suggesting Low Risk Nodules Hyperechoic nodule (especially in autoimmune thyroiditis) Pseudonodules in Hashimoto s Pure cyst without a solid component Colloid with reverberation artifact comet tails Spongiform Echotexture

6 Hyperechoic with background of Hashi s Nodule

7 Hyperechoic with background of Hashi s

8 Colloid within Nodule with Comet Tails

9 Colloid Within Nodule Cat s Eye (Comet Tail, Reverberation or Ringdown artifact)

10 Moon Radiology 2008; 247: Bonavita AJR 2009; 193: Spongiform nodules aggregation of multiple microcystic components in more than 50% of the volume of the nodule honeycomb of internal cystic spaces Only 1 in 360 spongiform nodules malignant 99.7% Specificity (Moon)

11 Spongiform echotexture

12 Spongiform Echotexture Note: Bright Linear Reflectors all posterior to the microcystic areas

13 What is the best description of this right lobe finding? A) It s a cyst because there is posterior acoustic enhancement B) It is ATA very low risk C) It could be a solid nodule, turn on Doppler to check D) It has an irregular halo

14 Thin-walled Cyst Enhancement

15 Looks cystic, but?

16 Halos & Margins Halo: sonolucent rim around an iso/hyperechoic nodule representing capsule Thin/regular lower risk Thick/irregular higher risk Hypoechoic Nodules ---- Margins: Smooth and regular Poorly Defined: interface between nodule and surrounding parenchyma is difficult to delineate Can be seen in hyperplastic nodules Irregular: the demarcation between the nodule and parenchyma is clearly visible but demonstrates and irregular, infiltrative or spiculated course. Higher risk

17 Halo Halo Edge Artifact

18 No Halo, but a Smooth Margin

19 Halo Thin Halo Benign Follicular Adenoma Thick, Irregular Halo Follicular CA

20 Subtle differences in halo Isoechoic Nodules Irregular halo Thinner halo

21 Margins Irregular Poorly defined, but not infiltrative (spongiform)

22 Infiltrative/Irregular Borders

23 Suspicious Sonographic Features Hypoechoic Microcalcifications Infiltrative margins Taller than wide on transverse view Abnormal cervical lymph nodes

24 Hypoechoic Compare to strap muscles and SCM

25 Hypoechoic

26 Hypoechoic

27 Markedly Hypoechoic

28 Calcifications Macrocalcifications: hyperechoic spots with acoustic shadowing ( dense calcifications ) Low-intermediate risk Microcalcifications: hyperechoic spots without acoustic shadowing (thought to represent psammoma bodies) (<1mm) High Risk Rim (eggshell) calcifications: curvi-linear hyperechoic calcification along periphery Higher risk if interrupted

29 Macrocalcification Patterns

30 Coarse Macrocalcification in PTC

31 Eggshell Calcifications with Shadowing Smooth Eggshell Maybe Reassuring Interrupted Eggshell Not reassuring

32 PTC in Graves Left lobe showing background heterogeneity and a calcified nodule which proved to be papillary thyroid cancer on FNA biopsy in this patient with

33 Microcalcification vs Comet Tail

34 Microcalcifications

35 Microcalcifications Dense and Microcalcifications

36 Microcalcifications in Papillary Cancer May be confused with comet tails If in doubt - assume microcalcifications

37 Small hyperechoic linear streaks just posterior to small cystic area NOT microcalcifications: sagittal sagittal

38 Microcalcifications

39 Transverse Longitudinal Calcifications in PTC

40 PTC

41 Does this nodule have microcalcifications? A. Yes B. No

42 Cystic PTC

43 Cystic PTC - UGFNA 4cm Left Cystic Nodule FNA - PTC

44 Invasion of Strap Muscle

45 Invasion of Carotid Sheath

46 Invasion of Trachea Cystic Papillary carcinoma invading the Trachea. Note the classic intra-cystic Cauliflower appearance.

47 Taller than wide Nodule is taller than wide on the transverse view

48 What About Intranodular Flow? B-Mode Power Doppler NO LONGER CONSIDERED AN INDEPENDENT

49 PTC lack of Doppler Don t be re-assured by lack of Doppler flow!

50 US Prediction of Thyroid Cancer Sensitivity Specificity Microcalcifications 45% 85% Absence of halo 66% 46% Poorly defined margins 64% 77% Hypoechoic 80% 45% Increased Doppler flow 67% 81% Taller than Wide 48% 92% MicroCa 2+ + irreg margin 30% 95% MicroCa 2+ + hypoechoic 28% 95% Solid + hypoechoic 73% 69% Brkljacic J Clin Ultrasound 1994; Takashima J Clin Ultrasound 1994; Rago Euro J Endorinol 1998; Cerbone Horm Res 1999; Leenhardt J Clin Endocrinol Metab 1999; Kim AJR 2002;

51 Factors Contributing to Variability of US Reporting US machine properties Probe frequency Gain, power output Use of harmonics or post image acquisition software e.g. smoothing Image interpretation Static vs. real time Use of video Patient factors Depth of nodule

52 US Pattern Recognition While individual features are suggestive, combining features and pattern recognition are the keys to US risk stratification of thyroid nodules

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54 Russ G. Ulttasonography 2016; 35: Moon WJ Radiology 2008; 247: Cystic or almost completely cystic almost universally benign Spongiform composition 0 points Colloid cyst No FNA Mixed Cystic-Solid -- 2 points (w/ no suspicious features)

55 ACR TI-RADS System FNA Indications TIRADS 3-5 Consider FNA

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57 Kappa values TIRADS - Interobserver TIRADS 2-5 TIRADS 4-5 Cheng et al. Russ et al.

58 ATA 2015: Nodule Sonographic Pattern Risk of Malignancy High Suspicion 70-90% Intermediate Suspicion 10-20% Low Suspicion 5-10% Very low Suspicion <3% Benign <1% Haugen et al. Thyroid; October 2015

59 Which of the following statements regarding FNA is most accurate? A. All nodules greater than 1-1.5cm should undergo FNA B. A high suspicion nodule with benign initial does not require repeat FNA C. FNA is indicated for all nodules with calcifications D. Size is more important than characteristics when considering a nodule for FNA

60 R8 US Pattern and suggested FNA cutoffs Sonographic Pattern Estimated malignancy risk FNA size cutoff Strength of rec Quality of evidence High suspicion >70-90% > 1 cm Strong Moderate Intermediate 10-20% > 1 cm Strong Low suspicion Low suspicion 5-10% > 1.5 cm Weak Low Very low suspicion < 3% > 2 cm Weak Moderate One option is surveillance Benign < 1% No biopsy Strong Moderate FNA is not recommended for nodules that do not meet the above criteria, Strong Moderate Haugen et al. Thyroid; January 2016

61 Micronodules Concerning for PTC

62 Sonographic appearance of micro PTC and risk 50% 14% 2% 30% <5% Risk of invasion starts at >= 7mm

63 R23 Follow-up of nodules with benign cytology Sonographic Pattern High suspicion Intermediate/ Low suspicion Very low suspicion Repeat US and US FNA within 12 months Repeat US at 12-24m If growth or new suspicious US feature, repeat FNA OR continued observation Utility of surveillance US and assessment of nodule growth as an indicator for repeat FNA is not known. If repeated, US should at > 24 months IF 2 nd US FNA done with benign cytology, US surveillance for continued risk of malignancy is Strength of rec Strong Weak Weak Strong Quality of evidence Moderate Low Low Moderate

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65 Conclusions Ultrasound is the cornerstone of thyroid nodule evaluation and always includes evaluation of the regional lymph nodes Pattern recognition is more valuable than individual suspicious features FNA decision making is based on the risk stratification of the nodule pattern