Acoustic Radiation Force Impulse Technology Research Articles

Preliminary Study on the Diagnostic Value of Acoustic Radiation Force Impulse Technology for Differentiating Between Benign and Malignant Thyroid Nodules

This study aimed to evaluate the diagnostic value of acoustic radiation force impulse (ARFI) elasticity imaging for differentiating between benign and malignant thyroid lesions. Hospitalized patients needing thyroid surgery were evaluated. After routine thyroid sonography, the patients underwent ARFI elasticity imaging. Virtual Touch tissue imaging (VTI) and Virtual Touch tissue quantification (VTQ; Siemens Medical Solutions, Mountain View, CA) were used to qualitatively and quantitatively analyze the elasticity and hardness of nodules. For statistical analysis, the Student t test, analysis of variance, and the χ(2) test were used to compare the elastic parameters. Of the 98 thyroid nodules observed in 72 hospitalized patients, 56 were nodular goiters, 16 thyroid adenomas, 4 thyroiditis, and 22 thyroid malignancies, with mean VTQ values ± SD of 2.034 ± 0.484, 1.835 ± 0.364, 2.293 ± 0.787, and 3.941 ± 1.393 m/s, respectively. The elastic parameters of malignant nodules were significantly higher than those of benign nodules (P < .001) and the surrounding thyroid parenchyma (P < .001). There was no significant difference between the VTQ value of benign nodules and that of the surrounding normal thyroid parenchyma (P > .05). For differentiating between benign and malignant nodules, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accordance rate were 86.36%, 93.42%, 79.17%, 95.95%, and 91.84% based on the standard VTQ value (2.555m/s). In total, 77.6% (59 of 76) of the benign nodules showed softer and equal images in the VTI mode, and 77.3% (17 of 22) of the malignant nodules showed stiffer images (P < .001). Acoustic radiation force impulse imaging has high sensitivity and specificity in evaluating benign and malignant thyroid nodules and therefore had good diagnostic value in clinical applications.

Virtual Touch Tissue Quantification Using Acoustic Radiation Force Impulse Technology

The purpose of this study was to investigate the clinical usage of Virtual Touch tissue quantification (VTQ; Siemens Medical Solutions, Mountain View, CA) implementing sonographic acoustic radiation force impulse technology for differentiation between benign and malignant solid breast masses. A total of 143 solid breast masses were examined with VTQ, and their shear wave velocities (SWVs) were measured. From all of the masses, 30 were examined by two independent operators to evaluate the reproducibility of the results of VTQ measurement. All masses were later surgically resected, and the histologic results were correlated with the SWV results. A receiver operating characteristic curve was calculated to assess the diagnostic performance of VTQ. A total of 102 benign lesions and 41 carcinomas were diagnosed on the basis of histologic examination. The VTQ measurements performed by the two independent operators yielded a correlation coefficient of 0.885. Applying a cutoff point of 3.065 m/s, a significant difference (P < .001) was found between the SWVs of the benign (mean ± SD, 2.25 ± 0.59 m/s) and malignant (5.96 ± 2.96 m/s) masses. The sensitivity, specificity, and area under the receiver operating characteristic curve for the differentiation were 75.6%, 95.1%, and 85.6%, respectively. When the repeated non-numeric result X.XX of the SWV measurements was designated as an indicator of malignancy, the sensitivity, specificity, and accuracy were 63.4%, 100%, and 89.5%. Virtual Touch tissue quantification can yield reproducible and quantitative diagnostic information on solid breast masses and serve as an effective diagnostic tool for differentiation between benign and malignant solid masses.

Ultrasonographic tissue quantification of the breast using acoustic radiation force impulse technology: phantom study and clinical application

The aim of this study was to perform the phantom experiment and demonstrate the clinical usefulness of tissue quantification using a linear array transducer and acoustic radiation force impulse (ARFI) technology. For the phantom study, the commercially available Elasticity QA Phantom Model 049 was used. First, we measured the shear wave velocity (m/s) for the four spheres and the background of the phantom. Then, the shear wave velocity at nine sites was measured, with the region of interest being moved gradually from a shallow region (3 mm) to a deeper region (38 mm). For the clinical study, the shear wave velocities of 15 solid breast mass lesions were measured. The phantom study confirmed the feasibility of quantitative determination of the degree of tissue hardness. Dispersion of the measured values tended to be somewhat increased for the depths of 3 mm and 38 mm. The mean shear wave velocity was 2.07-2.93 m/s for five benign lesions, whereas higher shear wave velocities (n = 2) (7.15, 7.44 m/s) or "X.XX" (unmeasurable state) (n = 7) were found for malignant lesions other than mucinous carcinoma (2.44 m/s). ARFI tissue quantification is a potentially promising ultrasonographic technique for diagnosing breast lesions.

An abdominal and thyroid status with Acoustic Radiation Force Impulse Elastometry – A feasibility study

Acoustic Radiation Force Impulse (ARFI) is a new method for the quantification of tissue elasticity. To date, ARFI technology has not been applied systematically to establish an abdominal and thyroid status. The aim of this prospective feasibility study was to evaluate ARFI elastometry performed on various healthy abdominal organs and the thyroid gland. 94 patients (43 females, 51 males) with a mean age of 54 years and 20 healthy controls were enrolled in the study. A routine ultrasound examination of the abdomen was scheduled in 72, and of the thyroid in 25. ARFI elastometry was performed in liver, spleen, pancreas, prostate, kidneys and thyroid gland with the ultrasound system Acuson S2000. ARFI values are proportional to tissue elasticity. Patients with ultrasonic or anamnestic evidence of diseased organs were excluded from the analysis. ARFI measurements were compared with the aid of the t-test and correlated using Spearman's correlation coefficient. ARFI elastometry proved feasible and the measurements obtained in the various organs differed significantly. Among healthy organs the spleen showed the highest mean ARFI velocities, followed by the kidney, thyroid, pancreas and the prostate. The lowest ARFI values were regularly found in healthy liver. Measurements in the kidneys and the spleen showed high standard deviation. ARFI elastometry may describe parenchymal stiffness of various abdominal organs and the thyroid gland. Further investigations are needed to compare these baseline findings in healthy organs with those of various tumours or diseases affecting the individual organs.

Tissue Quantification With Acoustic Radiation Force Impulse Imaging: Measurement Repeatability and Normal Values in the Healthy Liver

The purpose of this study was to describe the most reliable measurement procedure for acoustic radiation force impulse technology and to define the normal wave velocity values in a healthy liver. Twenty healthy volunteers underwent acoustic radiation force impulse imaging tissue quantification and were enrolled in this prospective study. All patients were examined by two independent operators at the same time. Twenty-four measurements per subject were obtained. Intraoperator and interoperator evaluations were performed. Statistical comparison of all mean data was performed with Student's t test. A value of p < 0.05 was considered significant. A comparative analysis was performed, and interclass correlation coefficients were calculated. The operators obtained 960 measurements. A statistically significant difference was found between the mean shear wave velocity values obtained by one operator deep in the right lobe of the liver and the values obtained on the surface of the right lobe (1.56 vs 1.90 m/s) and between the mean values obtained deep in the right lobe and those obtained deep in the left lobe (1.56 vs 1.84 m/s). The other operator had similar results. The distribution of all mean values obtained by both operators deep in the right hepatic lobe exhibited less dispersion (95% CI, 1.391-1.725) than those obtained on the surface (95% CI, 1.664-2.136). In 77.5% of cases, the shear wave speeds were between 1 and 2 m/s. No statistically significant difference was found in the comparisons performed on the right hepatic lobe by the two operators. The interclass correlation coefficient calculated for measurements deep in the right lobe was 0.87 (p < 0.0001). Acoustic radiation force impulse imaging quantification of hepatic tissue is more reproducible when applied to the deeper portion of the right lobe of the liver.