# Relationship between the mean diameter of the thyroid lobes and the transverse diameter of the trachea: an ultrasound marker for goiters

## TL;DR

This study shows that the ratio of thyroid lobe diameter to trachea diameter measured by ultrasound can reliably detect goiters.

## Contribution

The study introduces a new ultrasound-based biomarker for goiter detection using the MTLD:TTD ratio.

## Key findings

- An MTLD:TTD ratio exceeding 1.7 cm in adults and 2.4 cm in children/adolescents reliably indicates goiter.
- The MTLD:TTD ratio has 89% sensitivity and 93% specificity for goiter detection.
- The biomarker shows a strong linear correlation with thyroid volume (R² = 0.82).

## Abstract

To evaluate the relationship between the mean thyroid lobe diameter (MTLD)
and the transverse tracheal diameter (TTD), as determined by ultrasound, in
order to validate its efficacy as a quantitative marker of goiter.

Thyroid ultrasound images were analyzed. Standardized measurements included
the MTLD [(transverse + anteroposterior diameter) ∕ 2], TTD, and thyroid
volume [transverse diameter × anteroposterior diameter ×
length × 0.470]. Statistical correlation and regression analyses were
employed to assess the interactions among those variables and their
diagnostic utility in goiter detection.

A total of 300 thyroid ultrasound images (200 of adults and 100 of
children/adolescents) were evaluated. We identified a significant
correlation between the MTLD:TTD ratio and goiter. When the MTLD exceeded
the normative TTD threshold (> 1.7 cm in adults; > 2.4 cm in
children/adolescents), the mean thyroid volume was consistently elevated, in
the adult patients—12.5 ± 2.1 mL (normal range, 7–10 mL)—and in the
pediatric patients—18.3 ± 3.6 mL (normal range, 5.0–16.1
mL)—confirming goiter (p < 0.001). Regression analysis
demonstrated a strong linear relationship between thyroid volume and the
MTLD (R² = 0.82; β = 1.34; p < 0.001), with 89%
sensitivity and 93% specificity for goiter prediction. An abnormal tracheal
index (1.7–2.4 vs. the observed mean of 2.6 ± 0.3) was found to
increase diagnostic accuracy (AUC = 0.94; 95% CI: 0.91–0.97).

The MTLD:TTD ratio is a reliable ultrasound biomarker for goiter detection,
demonstrating strong diagnostic performance and volumetric correlation.