Systematic differences between ultrasound and pathological evaluation of thyroid nodules: a method comparison study.

Area of Science:

• Endocrinology
• Radiology
• Pathology

Background:

• Thyroid nodule size is crucial for clinical decisions.
• Discrepancies between ultrasound size (USS) and pathological size (PS) are common but not systematically analyzed.
• This study aimed to quantify bias between USS and PS measurements.

Purpose of the Study:

• To uncover and analyze systematic differences (bias) between ultrasound size (USS) and pathological size (PS) measurements of thyroid nodules.
• To determine if USS and PS measurements are interchangeable in clinical practice.
• To investigate potential discrepancies in size classification for smaller nodules.

Main Methods:

• Retrospective analysis of 121 patients undergoing thyroidectomy for solitary nodules.
• Ordinary least product regression to assess constant and proportional bias in unidimensional USS and PS.
• Comparison of 3D volume measurements in a subgroup of 31 patients.
• Defined acceptable interchangeability limits as a 20% difference.

Main Results:

• No significant constant or proportional bias was found between USS and PS (regression: USS = 0.863 + 1.040 × PS).
• Discrepancies were noted for nodules <10 mm (P=0.004).
• Overtreatment due to USS >10 mm but PS <10 mm occurred in 4.1% of patients.
• Subgroup analysis of 3D volume measurements showed no bias.

Conclusions:

• USS and PS measurements are generally interchangeable, with no significant systematic bias.
• USS may misclassify smaller thyroid nodules, potentially leading to unnecessary workup and overtreatment.
• Clinical decisions, especially for smaller nodules, should consider potential discrepancies between USS and PS measurements.