Ultrasound of Thyroid Nodules:Guidelines and Trends

Ann Podrasky MD, FSRUAssociate Clinical Professor, Florida International University

Adjunct Professor, Miami Dade CollegeSection Chief, Ultrasound, Baptist Health South Florida

Disclosures

Ann Podrasky: Consultant: Siemens Healthineers

Brand names are included in this presentation for participant clarification purposes only. No product promotion should be inferred.

Thyroid Cancer: SEER 2019, U.S. pop.

Thyroid Cancer Trends

• In U.S., incidence ↑3x, 4.8 to 15 per 100,000 1975-2014– 3.3% of all cancers in the United States in 2012

• Trend: disproportionate increase in diagnosis of small papillary thyroid cancers without significant change in mortality (0.5 per 100,000 people)

• Higher incidence due to the Ultrasound detection of subclinical disease and possibly environmental factors.

Nodule Guidelines should apply to all types of Thyroid Cancer

• Papillary thyroid carcinoma: 80% of thyroid malignancies and often contains macro- and microcalcifications

• Follicular carcinomas: next most common malignancy, account for 11% of thyroid malignancy

• Medullary carcinomas:– more frequently sporadic– may be familial in association with multiple endocrine neoplasia type 2 (MEN 2a)

• Anaplastic carcinomas: usually ill-defined or infiltrative lesions

• Don’t forget about non-thyroidal Nodules!• Lymphoma• Metastases

Which Thyroid Nodule Guideline?

This Photo by Unknown Author is licensed under CC BY-SA

ACR-TIRADS

ATA

K-RADS

EU-TIRADS

NCCN

Hx of Thyroid Nodule Guidelines

• Society of Ultrasound in Radiologists (SRU) Consensus: 2005• 1st TIRADS: Horvath etal 2009• ATA: 2009 Guidelines and Management• KRADS: 2010• ATA revised: 2015 Guidelines and Management• EU-TIRADS: 2017• ACR-TIRADS: 2017

Thyroid Ultrasound ScanningKey to Success is Organization• Use protocol-driven exams

– Order of imaging standardized

• Static imaging (Long and Trans), then do dynamic clips, then measure nodules

• Accuracy in imaging:– Don’t be limited by probe footprint to measure a length or view large nodule

• Use Trapezoid feature, extended field of view– Consider all probes and frequencies, change settings– Look at forest not trees

• Look for outer nodule margin, not just any rounded area

• Measure nodules SUPERIOR to INFERIOR– Makes it easier to localize for bx

• Always include full survey of lymph nodes

Report descriptors are best CommunicationACR Lexicon for Nodules Terminology!

• Composition• Solid• Cystic• Mixed • Spongiform

• Echogenicity• Hyper-, isoechoic• Hypoechoic

– Don’t overcall hypoechoic!—many are isoechoic with hypoechoic rim• Very hypoechoic, more than muscle, more suspicious

• Shape– Taller than wide– Round– Oval

• Margin– Lobular– Irregular

• Calcifications– Punctate echogenic foci– Macroca++– Foci with comet-tail artifacts

Grant E etal, JACR 2015 Dec.1272-1279

Classic features PTC

SolidHypoechoicOvalLobularMicroCa++

What is best guideline? All use combination of features

• Hypoechoic• Taller than wide (transverse plane)• Solid or solid and cystic• Microcalcifications• Macrocalcifications• Lobular or irregular borders

• Color or power doppler vascularity: not considered predictive

• Hypoechoic rim: not specific– Thin, even: tendency to benign– Thick, irregular: tendency to Ca

• Size: not independent risk factor for malignancy but guides management– Follicular, Hurthle cell tend to be larger

• Number of nodules: no safety

Multiple Societies have Guidelines for Nodule Management

Higher Sensitivity

KTANCCNATA

Higher Specificity

AACEACR-TIRADS

FSESRU

Lowest Rate of Unnecessary FNAB

ACR-TIRADSFSE

AACESRUATA

NCCNKTA

57 y/o Fpapillary Ca

ACR TIRADS

acr.org

Risks CaMiddleton etal AJR 2017

Goal of ACR TIRADS: Reduce the number of Benign Biopsies

• Higher size cutoffs for low suspicion nodules

• Thyroid cancers > 1cm that are potentially missed will be followed up

• Various recent studies support– Atilla K etal, Endocrine, 2018 Sep; 61(3): 398-402

• 2847 nodules bx’d under 2009 ATA reclassified by ACR TIRADS, 98.8% of TIRADS 2 and 3 were benign

Higher risk of missing malignancy for ACR vs. ATA

– ATA and ACR had similar diagnostic efficacy overall (223 nodules):

• ATA: sens. 77.3%, spec. 76.6%, PPV 55.3%, NPV 90%• ACR: “ 78.4%, “ 73.2%, “ 52.3%, “ 90%

– Subanalysis of TR3 and TR4 < 1.5 cm:• 40 TR3, 10% malignant• 31 TR4, 38% malignant

Ahmadi etal Endocrine Practice 2019, May; 25(5): 413-422. retrospective review

ATA and ACR comparison points

• Similarities:– Similar lexicon for morphology– Relative categories of Low, Intermediate, High suspicion

• Differences:– Mixed iso- or hyperechoic solid and cystic nodule without Ca++ would score TIRADS 2 in ACR

(no FNA) vs. ATA (FNA > 1.5 cm)

– ACR TIRADS has higher cutoff sizes than ATA for FNA for TIRADS 3 (2.5 vs. 2.0 cm) and TIRADS 4 (1.5 vs. 1.0 cm)

– ACR suggests to limit number of nodules to follow to 4, and assign each a TIRADS score, ATA does not

Trends in Reporting

• Structured reporting– Automated transfer of lobe measurements into report

• Reduces errors of voice recognition dictation

– Further automation• Nodule measurements

– Follow nodule growth over time

Cervical Lymph Node evaluation

• Every thyroid Ultrasound document Levels 2-6• Routinely image in trans

– Abnormal? Take long and Color doppler

• Pt. has known positive biopsy: do detailed lymph node mapping

• Post-thyroidectomy surveillance

30 y/o M

Inconclusive FNA (Bethesda III)

• 20-30% of cases• Use molecular testing:

– Multiple markers now available to guide management pre-operatively

– One recent article uses K-RAS to increase rate of malignancy to 50% in combination with US TIRADS

• (Wu etal, PLoS ONE 14(7): e0219383)

Elastography Thyroid NodulesStrain vs. 2D-Shear Wave• Strain is compression technique initially used, operator

dependent (WFUMB guidelines 2017, European)

• Meta-analysis for 131 studies detecting malignant thyroid nodules using SWE:– Sensitivity, 84.3 %, specificity 88.4 % and ROC characteristics 93 % – PPV: 27.7–44.7 % and NPV: 98.1–99.1 % in screening analysis.

• ARFI imaging w/ pSW velocity vs. ARFI imaging alone: ↑ specificity (100% vs. 80.0%) & PPV (100 % vs. 72.9%)– ARFI elastography is useful tool in differentiating malignant from

benign thyroid nodules with Bethesda category III results on FNAC

Lin P etal European RadiologyNovember 2014, Volume 24, pp 2729–2738

Zhao C etal, Oncotarget. 2017 Jan 3;8(1):1580-1592.

AUS/FLUS original Dx

• Are the shear wave physics as applicable in thyroid nodules similar to liver?

• Artifacts?• What are cut-off values for

each manufacturer?

Zhao C, Ultrasonography Apr 2019

Microvascular Imaging• Suppresses motion artifact and still displays weak signal

in small vessel flow• Utility of info on malignant vessels?

Kong J etal JUM 2017

Contrast-enhanced UltrasoundNeck Lymph Node Architecture

Radiopaedia.org

Summary

• Guidelines used right now depends on your local practice– Multidisciplinary approach is best

• ATA and ACR-TIRADS hopefully will meet in consensus panel

• Consider Ultrasound features of nodules in light of patient risk factors and clinical judgement