Thyroid image reporting and data system (TI-RADS)

TI-RADS is a risk stratification system for classifying thyroid lesions, originating from a study from 2009 3, and described in an American College of Radiology (ACR) white paper in 2015 1. Its use was originally advocated in a similar vein to the use of BI-RADS for breast lesions. 

In 2017, a new white paper 2 was released by the ACR committee on thyroid imaging with a standardized scoring system, with guidance on fine needle aspiration (FNA) and follow-up. This resulted in the revised ACR TI-RADS system which superseded the original TI-RADS described herein.


Originally this classification system was proposed by Horvath et al. 3 in 2009, with a modified recommendation from Jin Kwak et al. in 2011 4.

Similar to BI-RADS category, the sonographic TI-RADS classification was as follows:

  • TI-RADS 1: normal thyroid gland
  • TI-RADS 2: benign lesions
  • TI-RADS 3: probably benign lesions 
  • TI-RADS 4: suspicious lesions (subclassified as 4a, 4b, and later 4c 4 with increasing risk of malignancy)
  • TI-RADS 5: probably malignant lesions (more than 80% risk of malignancy)
  • TI-RADS 6: biopsy proven malignancy
TI-RADS 2 category
  • 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)

These conditions have 0% risk of malignancy.

TI-RADS 3 category
  • hyperechoic, isoechoic or hypoechoic nodules, with partially formed capsule and peripheral vascularity, usually in setting of Hashimoto thyroiditis (Hashimoto pseudonodule)

Modified TIRADS classification 4 have simplified TIRADS 3 category as none of the suspicious malignant sonographic features described below. These lesions are mostly benign with <5% risk of malignancy 3.

TI-RADS 4 and 5 categories

These categories are based on five suspicious sonographic features of malignancy:

  • solid component
    • high stiffness of nodule on elastography if available
  • markedly hypoechoic nodule
  • microlobulations or irregular margins
  • microcalcifications
  • taller-than-wider shape
  • TI-RADS 4a: one suspicious feature
  • TI-RADS 4b: two suspicious features
  • TI-RADS 4c: three/four suspicious features
  • TI-RADS 5: all five suspicious features

TI-RADS 4a has 5-10% risk of malignancy, 4b and 4c may have 10-80% risk of malignancy. TI-RADS 5 category lesion have >80% risk of malignancy 3.

See also

Thyroid pathology
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Article information

rID: 21448
System: Head & Neck
Synonyms or Alternate Spellings:
  • Thyroid Image Reporting and Data System
  • TIRADS (Thyroid Image Reporing and Data System)

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