IS TIRADS A PRACTICAL AND ACCURATE

SYSTEM FOR USE IN DAILY CLINICAL PRACTICE?

Presented by Dr Roshan Valentine

PG Resident

St Johns Medical College Bangalore

AUTHORS:Anuradha Chandramohan, Abhishek Khurana, B T Pushpa, Marie Therese Manipadam1, DukhabandhuNaik2,Nihal Thomas2, Deepak Abraham3, MazhuvancharyJacob Paul3, CMC Vellore

INTRODUCTION

• 12% of adult Asian population have a palpable nodule

• 80% among children in iodine-deficient parts of India.

• Incidence of thyroid cancer is low.

• Ultrasound is a widely accepted imaging modality for the initial assessment

• Thyroid Imaging Reporting and Data System (TIRADS) described by Kwak et al.[15] is a relatively simple system which can be easily adopted

OBJECTIVE

To assess

• Positive predictive value

• Inter-observer variability of TIRADS

MATERIALS AND METHODS

STUDY POPULATION• IERB Review

• Dept of radiology at CMC vellore

• Jan 2012 – nov 2012

• Estimated sample size for assessing inter-reader reliability – 250

• 346 nodules of 307 pts

INCLUSION CRITERIA• Solitary nodule and nodules in MNG > 1cm

• FNAC – benign/malignant lesion

• Undergone Surgery -FNAC yielded suspicious for malignancy, indeterminate or inadequate sampling

MATERIALS AND METHODS

THYROID ULTRASOUND• ACUSON S2000 AND ACUSON ANTARES Siemens

• 7-11Mhz probe

• 2 radiologists with 8 years experience

• Reviewed by a 3rd radiologist (3 yrs experience)

• Features assessed for :

1)Composition: solid cystic mixed

2)Echogenicity

3)margins: well defined +/- halo sigin , microlobulated , ill-defined , irregular

4)Calcification :micro/macro

5) Shape : round/t>w or oval

MATERIALS AND METHODS

THYROID ULTRASOUND

Features suggesting malignancy :• Hypoechoic or markedly hypoechoic

• Irregular/spiculated

• Microlobulated

• Ill defined/fuzzy margins

• Microcalcifications

• Round shape

MATERIALS AND METHODS

TIRADS CATEGORISATION

• Cat 2: completely cystic , comet tail artefacts or spongiform

• Cat 3: Solid, oval, well-defined, isoechoic nodules

• Cat 4 a, b and c

THYROID FNAC

• FNAC b/w 12h to 2 days post USG

• By Surgeon and radiologist

• 2-3 aspirations by 23g needle attached to 5cc syringe

• Cytology technician to confirm the adequacy of the specimen

• BETHESDA system by cytopathologists for classification• Class I: inadequate

• Class II : benign

• Class III: atypical or follicular cells of indeterminate significance

• Class IV: follicular neoplasm

• Class V: suspicious for malignancy

• Class VI : Malignant

THYROID FNAC

TIRADS≤3 + non diag

FN/HPE+notplanned for Sx

Follow for 1 year with USG every 6mnth

No change in nodule

BENIGN

STATISTICAL ANALYSIS

• SPSS analytics 16.0 software

• Receiver operating characteristic (ROC) curve for TIRADS efficacy

• Inter-rater reliability was measured using the quadratic weighted kappa statistics,

RESULTS

• Total of 272 nodules : 154 benign ; 118 malignant

• Malignancy : M>F

• Among malignant nodules , males were older than females

RESULTS

RESULTS

RESULTS

Diagnostic performance of TIRADS on considering

Sn(%) Sp(%) PPV(%) NPV(%) Accuracy(%)

Benign: 2&3Malignant : 4a,4b,4c & 5

72 68.8 63.9 76.2 70.2

Benign 2,3 & 4aMalignant : 4b,4c & 5

60.2 85.1 75.5 73.6 74.2

RESULTS

INTER-OBSERVER AGREEMENT• Overall substantial agreement for assigning TIRADS category

• poor agreement for assigning TIRADS categories 4a and 4b

DISCUSSION

• Several classification system to stratify thyroid malignancy

Risk – complex

• The classification by Kwak et al is simple and similar to BIRADS and familiar to most radiologists – hence used

• Study by Kim et al reported the USG suspicious features malignancy

DISCUSSION

DISCUSSION

• PPV and specificity improved when TIRADs4a → 3.

• Thus its better to follow up 4a Pts than subjecting them to surgery

LIMITATIONS

• No prior training for examiners

• Referral centre – hence most of the lesions included were malignant(selection bias)

• 34/112 malignant nodules were follicular variant of papillary cancers – benign appearance.• TB thyroid – rare and can mimic malignancy

• False positive and false negative of cytology results

• USG – guided FNAC in only 30% , rest were blind FNAC by surgeons

CONCLUSION

• PPV for malignancy was high for TIRADS category 5 and 4c nodules

• Reassigning TIRADS 4a →3 will improve PPV and specificity.

• Overall agreement between observers for assigning TIRADS category was substantial

• Thus, TIRADS is a simple and practical method of assessing thyroid nodules and can be used in practice.

TIRADS

TIRADS 1 - normal thyroid gland

TIRADS 2 - benign lesions

TIRADS 3 - probably benign lesions

TIRADS 4 - suspicious lesions (subclassified as 4a, 4b and 4c with increasing risk of malignancy)

TIRADS 5 - probably malignant lesions (more than 80% risk of malignancy)

TIRADS 6 - biopsy proven malignancy