Acoustic radiation force impulse imaging: normal values of spleen stiffness in healthy children

Background Acoustic radiation force impulse (ARFI) imaging is a noninvasive ultrasound elastography technique for evaluating tissue stiffness. The association of liver and spleen stiffness provides additional information in the assessment of portal hypertension. The technique and normal values of spleen stiffness by point shear wave elastography (p-SWE) in pediatrics have not been well documented. Objective Our aim is to describe the feasibility and normal ARFI elastography values in the spleen for healthy children and to compare measurements in two different probe positions (the axial and sagittal planes). Materials and methods Spleen p-SWE using ARFI values were measured with a 6C1 probe in 102 healthy children (age range: 8 weeks to 17 years) divided into four age groups. An average of nine (standard deviation: two) spleen stiffness measurements were taken during free breathing in each plane (axial and sagittal). The impact of age and measurement plane in the spleen was analyzed using multivariate models. Results There was no significant difference in spleen stiffness values taken at different ages, with an average of the medians of 2.43±0.31 m/s. There was no significant difference based on probe orientation: sagittal plane (median: 2.46±0.29 m/s) and axial plane (median: 2.43±0.32 m/s) with Student’s t-test P=0.18. The mean depth of measurement varied between 2.3 cm and 3.7 cm, according to age. Conclusion Normal spleen stiffness values using ARFI imaging in children do not vary with age and correspond to a median of 2.43 m/s. No significant difference was found when using different probe positions.

Comparative Efficacy of Ultrasonography and Acoustic Radiation Force Impulse (ARFI) Elastography in Prediction of Malignancy in Thyroid Nodules

Objective: The incidence of malignancy in thyroid nodules is infrequent, but this trend may be reversing. The present study was conducted to emphasize the diagnostic accuracy of acoustic radiation force impulse (ARFI) imaging, in addition to conventional gray-scale ultrasonography (US), for differentiating benign and malignant thyroid nodules. Methods: A total of 141 patients with thyroid nodules (≥10 mm) were included in the study and were evaluated with US, Doppler, and ARFI elastography using Siemens S2000 Acuson ultrasound equipment. Results: The sonographic patterns most predictive and indicative of malignancy included irregular margins and presence of microcalcifications. The Doppler findings in isolation were not extremely sensitive in the detection of malignancy. The shear wave velocity cutoff value on ARFI imaging using receiver operating characteristic curves for differentiation of benign and malignant nodules were noted at 2.87 m/s. ARFI imaging performed better than US and Doppler with sensitivity of 75%, specificity of 96%, and accuracy of 94%. Conclusion: ARFI elastography could be utilized as a reliable initial screening test for detection of malignancy in thyroid nodules.

Role of Ultrasound Acoustic Radiation Force Impulse in Differentiating Benign from Malignant Superficial Lymph Nodes

Objective: The purpose of this study was to evaluate the diagnostic performance of acoustic radiation force impulse (ARFI) imaging in differentiating benign from malignant peripheral lymphadenopathy. Materials and Methods: This was a prospective study approved by the Institutional Review Board with financial grant for the same. Ultrasound and ARFI imaging of peripheral lymph nodes were performed and correlated with pathological results, which were used as the reference standard. The virtual touch tissue imaging and virtual touch tissue quantification parameters of ARFI were analyzed in 86 lymph nodes, of which 78 were included in the study. Using receiver operating characteristic curve analysis, the diagnostic usefulness of ARFI values were evaluated with respect to their sensitivity, specificity, and area under the curve. Results: The mean area ratio of benign lymph nodes was 0.88 (±0.2) and that of malignant lymph nodes was 1.17 (±0.14). The mean shear wave velocities (SWV) of benign and malignant lymph nodes were 2.02 m/s (±0.94) and 3.7 m/s (±2.27), respectively. The sensitivity and specificity of virtual touch imaging area ratio in differentiating benign from malignant lymph nodes was 97% and 77%, of SWV was 71% and 70%, and of SWV ratio was 68% and 79%, respectively. Conclusion: As ARFI was found to have a superior diagnostic performance over conventional ultrasound and color Doppler in the characterization of lymph nodes, we recommend its routine use in differentiating benign from malignant nodes.

Clinical utility of TIRADS and ultrasound elastography in characterization of thyroid nodules

Background: Thyroid nodules are a common entity in an iodine deficient population, however malignant nodules are relatively uncommon with excellent prognosis. Ultrasound elastography is a useful tool for characterization of nodules and allows selection of tumors for FNAC. This study aimed to evaluate the diagnostic value of strain elastography and acoustic radiation force impulse (ARFI) imaging in differentiating malignant from benign thyroid nodules.Methods: This study included 100 thyroid nodules evaluated using ultrasound TIRADS classification. Strain elastography evaluated the nodules using the elasticity score and strain ratio followed by VTI and shear wave velocity generated from ARFI data to characterize the nodules. Final diagnoses were obtained from cytological and/or histological evaluation. The diagnostic performance of the two elastography methods was analyzed and compared by multiple receiver operating characteristic curve analysis.Results: Of the 100 thyroid nodules observed in 100 patients (82 females and 18 males), 22% were malignant nodules and 78% were benign. The cut off values for elasticity scores, mean SR, VTI grade and mean SWV for predicting malignant thyroid nodules were greater than or equal to score 2, 2.4, grade 3, 2.5m/s respectively. The area under the receiver operating characteristic curve for elasticity score, mean SR, VTI grade and mean SWV was 0.79, 0.78, 0.89 and 0.84, respectively (P>0.05) and the accuracy was 74, 81.6, 88 and 87.5%, respectively (P>0.05). The accuracy of the combined use of conventional sonography, strain elastography and ARFI imaging was 85.6% respectively, which was higher than that of conventional sonography (P>0.05).Conclusions: Strain elastography and ARFI imaging have high sensitivity and specificity for differentiating malignant from benign thyroid nodules and therefore have good clinical utility in evaluating these lesions.