Rationale and Objectives
Thyroid nodules are common in the population, although the rate of malignancy is relatively low (5%–15%). The purpose of this study was to determine if introducing a modified standardized reporting format and management algorithm (Thyroid Imaging Reporting and Data System [TI-RADS]) affects radiologist reporting adherence, number of thyroid biopsies, and other measurable outcomes.
Materials and Methods
All thyroid biopsies performed over two 6-month periods were evaluated at a tertiary care hospital with Research Ethics Board approval. The first period was before implementation of TI-RADS and the second was several months after implementation of TI-RADS (using a modified version made through a multidisciplinary collaboration). The number of biopsies performed was determined in each of the two periods as well as the percent of positive malignancy, wait times, and rates of non-diagnostic/unsatisfactory and inconclusive biopsies, which included atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS).
Results
The average number of biopsies performed prior to implementing modified Kwak’s TI-RADS was 74 thyroid biopsies per month and the average number of diagnostic ultrasounds was 271. After the introduction of modified Kwak’s TI-RADS, the average number of thyroid biopsies decreased to 60 per month (an 18.9% reduction, P < .05), and the number of diagnostic ultrasound increased to 287 per month (a 5.9% increase from 2016 to 2017). The average wait time for a thyroid biopsy decreased from 5 to 3 weeks ( P < .05). There was a slight increase in the rate of positive malignancy results (from 15% to 18%), although it was not statistically significant. The rate of non-diagnostic/unsatisfactory and inconclusive results (including AUS and FLUS) remained unchanged (18% AUS/FLUS/15% non-diagnostic/unsatisfactory before and 17% AUS/FLUS/15% non-diagnostic/unsatisfactory after TI-RADS introduction, P > .05).
Conclusions
Introduction of a multidisciplinary-approved standardized reporting system with evidence-based management recommendations led to no statistically significant change in the number of diagnostic ultrasounds but a statistically significant reduction in the number of monthly thyroid biopsies and associated reduction in wait times.
Introduction
Studies have estimated that up to 67% of North Americans have thyroid nodules but that of these nodules only 5%–15% will be malignant . There has been a 2.4-fold increase in the incidence of thyroid cancer in the past 30 years; this increase in diagnosis is commonly considered to result from better technology and more frequent use of cross-sectional imaging . Despite an increase in overall thyroid diagnosis, the 5-year mortality rate for thyroid cancer has been stable at a relatively low 5%–7% since 2005 . Some studies estimate that up to 50% of thyroid cancers will remain indolent over a patient’s life time .
With more thyroid nodules being detected, emphasis should be placed on consistent imaging technique, template reporting use, and standardized management recommendations by radiologists. One of the main challenges in this sequence of events is determining which nodules require biopsy and which ones are better left alone ( Fig 1 ). A further concern is discerning which part of heterogenous nodules requires biopsy ( Fig 1 ).
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Methods
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TABLE 1
Modified Version of TI-RADS Used in Our Institution Entitled “COP-modified TI-RADS”
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COP, Community of Practice; TI-RADS, Thyroid Imaging Reporting and Data System; TOH, The Ottawa Hospital.
TABLE 2
Comparison of “COP-modified TI-RADS” to ATA Guidelines
COP-modified TI-RADS Definition COP-modified TI-RADS Management ATA Comparator Definition ATA Guideline Recommendation TR-1
NO ABNORMALITY IDENTIFIED No biopsy
No follow-up No specific category None TR-2
0% risk of malignancy BENIGN:
Spongiform
Colloid
Cyst
Giraffe hide pattern No biopsy
No follow-up BENIGN 0%
Purely cystic nodules (no solid component) No biopsy TR-3
<2% risk of malignancy
PROBABLY BENIGN:
Mixed composition
No suspicious US features No biopsy
No follow-up VERY LOW SUSPICION <3% risk of malignancy
Partially cystic nodules without any of the sonographic features described in low, intermediate or high suspicion patterns or Spongiform Consider biopsy at >20 mm (weak recommendation, low-quality evidence) TR-4F: New Thyroid COP designation*
DEFINITIONS
a) <10 mm and >1 “suspicious” features
b) Equivocal case (radiologist has low confidence in images provided)
c) Known prior cancer = (hemithyroidectomy) Yearly follow-up (indefinitely until category changes or until better evidence medicine published in literature) No specific guidelines exists as a direct comparison in ATA None as a direct equivalent to COP-modified TIRADS 4F does not exist in ATA TR-4A:
2%–10% risk of malignancy
LOW SUSPICION OF MALIGNANCY:
One suspicious US feature; eg, solid composition Follow-up at 12 months
Or
Biopsy at 15 mm if positive clinical factors (as per requesting physician) LOW Suspicion
5%–10% risk of malignancy
Isoechoic or hyperechoic solid nodule
Or
Partially cystic nodule with eccentric hypoechoic solid areas. NO microcalcification, irregular margin or extrathyroidal extension, or taller than wide shape Biopsy at 15 mm (weak recommendation, low-quality evidence) TR-4B*:
10%–20% risk of malignancy
INTERMEDIATE SUSPICION OF MALIGNANCY:
Solid AND hypoechoic to thyroid parenchyma Biopsy at 15 mm INTERMEDIATE Suspicion 10–20% risk of malignancy
Hypoechoic to thyroid
and > 95% solid nodule
With smooth margins Without microcalcifications, extrathyroidal extension, or taller than wide shape Recommend Biopsy at 1.5 cm (strong recommendation, low-quality evidence) TR-4B:
10%–50% risk of malignancy
INTERMEDIATE SUSPICION OF MALIGNANCY
Any TWO high suspicious features Biopsy at 10 mm HIGH Suspicion >70%–90%
Solid hypoechoic nodule or solid hypoechoic component of a partially cystic nodule with one or more of the following features: irregular margins (infiltrative, microlobulated), microcalcifications, taller than wide shape, rim calcifications with small extrusive soft tissue component, evidence of extrathyroidal extension Biopsy at 10 mm (strong recommendation, moderate-quality evidence) TR-4C:
50%–95% risk of malignancy
MODERATE CONCERN,
but not classic for malignancy:
(three or four suspicious US features) Biopsy at 10 mm Same as directly above Biopsy at 10 mm (strong recommendation, moderate-quality evidence) TR-5:
95% risk of malignancy
HIGHLY SUGGESTIVE OF MALIGNANCY:
Five suspicious US features from: solid composition, microcalcifications, taller than wide, hypoechoic, very hypoechoic, and irregular borders Biopsy at 10 mm Same as directly above Biopsy at 10 mm (strong recommendation, moderate-quality evidence)
ATA, American Thyroid Association; COP, Community of Practice; TI-RADS, Thyroid Imaging Reporting and Data System.
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Results
Adherence
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TABLE 3
Adherence Rate of Radiologist at the Beginning, Middle, and End of the Study Period
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Number of Biopsies
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TABLE 4
Average Number of Biopsies per Month Before and After the Introduction of TI-RADS
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Wait times
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TABLE 5
Average Wait Time for Thyroid Biopsies Across Our Institution Before and After TI-RADS Implementation ( P < .05)
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Malignancy Rates
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TABLE 6
Average Malignancy Rate of Confirmed Biopsies per Month Before and After TI-RADS Implementation ( P > .05)
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Insufficient/Inconclusive Rates
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Discussion
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PDSA/Adherence
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Number of Diagnostic Imaging Cases, Biopsies, and Wait Times
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Malignancy Rates
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Non-diagnostic/Unsatisfactory and AUS/FLUS Results
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Study Limitations
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Conclusion
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Acknowledgments
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