Acoustic radiation force impulse imaging for differentiation of thyroid nodules

PLoS One. 2012;7(8):e42735. doi: 10.1371/journal.pone.0042735. Epub 2012 Aug 29.


Background: Acoustic Radiation Force Impulse (ARFI)-Imaging is an ultrasound-based elastography method enabling quantitative measurement of tissue stiffness. The aim of the present study was to evaluate sensitivity and specificity of ARFI-imaging for differentiation of thyroid nodules and to compare it to the well evaluated qualitative real-time elastography (RTE).

Methods: ARFI-imaging involves the mechanical excitation of tissue using acoustic pulses to generate localized displacements resulting in shear-wave propagation which is tracked using correlation-based methods and recorded in m/s. Inclusion criteria were: nodules ≥5 mm, and cytological/histological assessment. All patients received conventional ultrasound, real-time elastography (RTE) and ARFI-imaging.

Results: One-hundred-fifty-eight nodules in 138 patients were available for analysis. One-hundred-thirty-seven nodules were benign on cytology/histology, and twenty-one nodules were malignant. The median velocity of ARFI-imaging in the healthy thyroid tissue, as well as in benign and malignant thyroid nodules was 1.76 m/s, 1.90 m/s, and 2.69 m/s, respectively. While no significant difference in median velocity was found between healthy thyroid tissue and benign thyroid nodules, a significant difference was found between malignant thyroid nodules on the one hand and healthy thyroid tissue (p = 0.0019) or benign thyroid nodules (p = 0.0039) on the other hand. No significant difference of diagnostic accuracy for the diagnosis of malignant thyroid nodules was found between RTE and ARFI-imaging (0.74 vs. 0.69, p = 0.54). The combination of RTE with ARFI did not improve diagnostic accuracy.

Conclusions: ARFI can be used as an additional tool in the diagnostic work up of thyroid nodules with high negative predictive value and comparable results to RTE.

MeSH terms

  • Acoustics
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Biopsy, Fine-Needle
  • Elasticity Imaging Techniques / methods*
  • Female
  • Humans
  • Male
  • Medical Oncology / methods
  • Middle Aged
  • Predictive Value of Tests
  • ROC Curve
  • Reproducibility of Results
  • Thyroid Nodule / diagnosis*
  • Thyroid Nodule / diagnostic imaging*
  • Ultrasonography / methods

Grant support

The authors have no support or funding to report.