Yi-Feng Zhang

Virtual Touch Tissue Quantification of Acoustic Radiation Force Impulse: A New Ultrasound Elastic Imaging in the Diagnosis of Thyroid Nodules

Objective Virtual touch tissue quantification (VTQ) of acoustic radiation force impulse (ARFI) is a new quantitative technique to measure tissue stiffness. The study was aimed to assess the usefulness of VTQ in the diagnosis of thyroid nodules. Methods 173 pathologically proven thyroid nodules in 142 patients were included and all were examined by conventional ultrasound (US), conventional elasticity imaging (EI) and VTQ of ARFI. The tissue stiffness for VTQ was expressed as shear wave velocity (SWV) (m/s). Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance. Intra- and inter-observer reproducibility of VTQ measurement was assessed. Results The SWVs of benign and malignant thyroid nodules were 2.34±1.17 m/s (range: 0.61–9.00 m/s) and 4.82±2.53 m/s (range: 2.32–9.00 m/s) respectively (P<0.001). The mean SWV ratios between each nodule and the adjacent thyroid tissue were 1.19±0.67 (range: 0.31–6.87) for benign and 2.50±1.54 (range: 0.85–6.69) for malignant nodules (P<0.001). ROC analyses indicated that the area under the curve was 0.861 (95% CI : 0.804, 0.918) (P<0.001) for SWV and 0.831(95% CI : 0.761, 0.900)(P<0.001) for the SWV ratio. The cutoff points for the differential diagnosis were 2.87 m/s for SWV and 1.59 for SWV ratio. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for EI were 65.9%, 66.7%, 66.5%, 40.3%, and 85.1%, respectively, and were 63.6%–75%, 82.2%–88.4%, 80.3%–82.1%, 58.9%–65.1%, and 87.7%–90.5%, respectively, for VTQ. The diagnostic value of VTQ is the highest for nodules >20 mm and lowest for those ≤10 mm. The correlation coefficients were 0.904 for intraobserver measurement and 0.864 for interobserver measurement. Conclusions VTQ of ARFI provides quantitative and reproducible information about the tissue stiffness, which is useful for the differentiation between benign and malignant thyroid nodules. The diagnostic performance of VTQ is higher than that of conventional EI.

Conventional US, US Elasticity Imaging, and Acoustic Radiation Force Impulse Imaging for Prediction of Malignancy in Thyroid Nodules

PURPOSE To evaluate conventional ultrasonography (US), US elasticity imaging (EI), and acoustic radiation force impulse (ARFI) imaging in thyroid nodule malignancy prediction. MATERIALS AND METHODS This prospective study was institutional review board approved; informed consent was obtained. Study included 375 patients (mean age, 51 years; range, 18-75 years) with 441 pathologically proven thyroid nodules. In 281 women (mean age, 50 years; range, 18-75 years) and 94 men (mean age, 53 years; range, 18-74 years), conventional US, EI, Virtual Touch tissue imaging (VTi; Siemens, Mountain View, Calif), and Virtual Touch tissue quantification (VTq; Siemens) of ARFI imaging were performed for each nodule. Multivariate logistic regression analysis was performed to assess 17 independent variables for malignancy prediction. Diagnostic performance was evaluated with receiver operating characteristic (ROC) curve analysis. RESULTS There were 325 benign and 116 malignant nodules. Marked hypoechogenicity (odds ratio [OR]: 83.88; 95% confidence interval [CI]: 17.81, 394.99) was the strongest independent predictor for thyroid malignancy, followed by shape taller than wide (OR: 8.69; 95% CI: 2.87, 26.31), VTi (OR: 6.54; 95% CI: 3.61, 11.88), moderate hypoechogenicity (OR: 3.98; 95% CI: 1.13, 14.05), poorly defined margin (OR: 3.27; 95% CI: 1.22, 8.77), female sex (OR: 2.55; 95% CI: 1.33, 4.91), coarse background of surrounding thyroid tissue (OR: 2.01; 95% CI: 1.12, 3.62), and VTq (OR: 1.78; 95% CI: 1.28, 2.47) (all P < .05). EI was not significantly associated with thyroid malignancy (P = .855). Area under the ROC curve (Az) for VTq and VTi was higher than that with other significant independent variables. Az, sensitivity, and specificity were 0.91 (95% CI: 0.87, 0.94) and 0.86 (95% CI: 0.82, 0.90), 80% and 71.6%, and 93.8% and 83.4%, respectively, for VTi and VTq. VTq of at least 2.87 m/sec and VTi of at least grade IV were the best cutoff values for malignant thyroid nodules. CONCLUSION ARFI imaging is promising for malignant thyroid nodule prediction, with higher diagnostic performance than conventional US or EI. ARFI can be used to supplement conventional US to diagnose thyroid nodules in patients referred for surgery.

Acoustic Radiation Force Impulse Imaging for Noninvasive Evaluation of Renal Parenchyma Elasticity: Preliminary Findings

Objective To evaluate the diagnostic value of acoustic radiation force impulse (ARFI) to test the elasticity of renal parenchyma by measuring the shear wave velocity (SWV) which might be used to detect chronic kidney disease (CKD). Methods 327 healthy volunteers and 64 CKD patients were enrolled in the study. The potential influencing factors and measurement reproducibility were evaluated in the healthy volunteers. Correlations between SWV and laboratory tests were analyzed in CKD patients.?Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of ARFI. Results The SWV of healthy volunteers correlated significantly to age (r = −0.22, P<0.001, n = 327) and differed significantly between men and women (2.06±0.48 m/s vs. 2.2±0.52 m/s, P = 0.018, n = 327). However, it did not correlate significantly to height, weight, body mass index, waistline, kidney dimension and the depth for SWV measurement (n = 30). Inter- and intraobserver agreement expressed as intraclass coefficient correlation were 0.64 (95% CI: 0.13 to 0.82, P = 0.011) and 0.6 (95% CI: 0.31 to 0.81, P = 0.001) (n = 40). The mean SWV in healthy volunteers was 2.15±0.51 m/s, while was 1.81±0.43 m/s, 1.79±0.29 m/s, 1.81±0.44 m/s, 1.64±0.55 m/s, and 1.36±0.17 m/s for stage 1, 2, 3, 4 and 5 in CKD patients respectively. The SWV was significantly higher for healthy volunteers compared with each stage in CKD patients. ARFI could not predict the different stages of CKD except stage 5. In CKD patients, SWV correlated to e-GFR (r = 0.3, P = 0.018), to urea nitrogen (r =  −0.3, P = 0.016), and to creatinine (r =  −0.41, P = 0.001). ROC analyses indicated that the area under the ROC curve was 0.752 (95% CI: 0.704 to 0.797) (P<0.001). The cut-off value for predicting CKD was 1.88 m/s (sensitivity 71.87% and specificity 69.69%). Conclusion ARFI may be a potentially useful tool in detecting CKD.

Virtual touch tissue imaging on acoustic radiation force impulse elastography: a new technique for differential diagnosis between benign and malignant thyroid nodules.

Acoustic radiation force impulse elastography is a newly developed ultrasound elasticity imaging technique that included both Virtual Touch tissue quantification and Virtual Touch tissue imaging (VTI; Siemens Medical Solutions, Mountain View, CA). This study aimed to evaluate the usefulness of VTI in differentiating malignant from benign thyroid nodules.

Solid hypo-echoic thyroid nodules on ultrasound: the diagnostic value of acoustic radiation force impulse elastography.

The aim of the study described here was to evaluate the diagnostic performance of acoustic radiation force impulse (ARFI) elastography in the differential diagnosis between benign and malignant solid hypo-echoic thyroid nodules (SHTNs) on ultrasound. In this retrospective study, 183 histologically proven SHTNs in 159 patients were enrolled. Conventional US, as well as Virtual Touch tissue imaging (VTI) and Virtual Touch tissue quantification (VTQ) of ARFI elastography, was performed on each nodule. The VTI features of SHTNs were divided into six grades, where higher grades represent harder tissue. VTQ was expressed as shear wave velocity, where higher shear wave velocity values indicate stiffer tissue. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value and Youden index for ultrasound and ARFI were assessed. The 183 pathologically proven SHTNs included 117 benign and 66 malignant lesions. Nodules classified as VTI grades IV to VI were more frequently malignant (49/66, 74.2%) than benign (10/117, 8.5%) (p < 0.001). The mean shear wave velocity of VTQ for malignant SHTNs (mean ± standard deviation, 4.65 ± 2.68 m/s; range, 1.36-9 m/s) was significantly higher than that for benign SHTNs (2.34 ± 0.85 m/s, 0-5.7 m/s) (p < 0.001). The sensitivity, specificity, accuracy, positive predictive value, negative predictive value and Youden index were 27.3%-84.8%, 13.7%-89.7%, 39.3%-69.4%, 35.7%-60%, 61.5%-78.5%, and -0.015 to 0.37 for ultrasound; 68.2%, 76.9%, 73.8%, 62.5%, 81.1% and 0.451 for VTQ; and 74.2%, 91.5%, 85.2%, 83.1%, 86.3% and 0.657 for VTI, respectively. ARFI elastography performed at a superior level, compared with conventional ultrasound, in the differential diagnosis between malignant and benign SHTNs. The diagnostic performance of VTI is higher than that of VTQ.

Acoustic Radiation Force Impulse Imaging: A New Tool for the Diagnosis of Papillary Thyroid Microcarcinoma

Purpose. To evaluate the diagnostic performance of ARFI imaging in differentiating between benign and malignant thyroid nodules <1 cm. Materials and Methods. 173 pathologically proven thyroid nodules (77 benign, 96 malignant) in 157 patients were included in this study. Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of conventional ultrasound (US) and ARFI imaging in papillary thyroid microcarcinoma (PTMC). The independent risk factors for predicting PTMC were evaluated. Results. The mean SWV value of benign and malignant thyroid nodules were 2.57 ± 0.79 m/s (range: 0.90–4.92 m/s) and 3.88 ± 2.24 m/s (range: 1.49–9.00 m/s) (P = 0.000). Az for VTI elastography score was higher than that for hypoechoic, absence of halo sign, and type III vascularity (P < 0.05). The optimal cut-offs for VTI elastography score and SWV were score 4 and 3.10 m/s. Gender, hypoechoic, taller than wide, VTI elastography score ≥ 4, and SWV > 3.10 m/s had been found to be independent risk factors for predicting PTMC. Conclusion. ARFI elastography can provide elasticity information of PTMC quantitatively (VTQ) and directly reflects the overall elastic properties (VTI). Gender, hypoechogenicity, taller than wide, VTI elastography score ≥ 4, and SWV > 3.10 m/s are independent risk factors for predicting PTMC. ARFI elastography seems to be a new tool for the diagnosis of PTMC.

Acoustic Radiation Force Impulse Elastography: A Useful Tool for Differential Diagnosis of Thyroid Nodules and Recommending Fine-Needle Aspiration: A Diagnostic Accuracy Study

Abstract To investigate the diagnostic performance of combined use of conventional ultrasound (US) and elastography, including conventional strain elastography such as elasticity imaging (EI) and acoustic radiation force impulse (ARFI) elastography, and to evaluate their usefulness in recommending fine-needle aspiration (FNA). A total of 556 pathologically proven thyroid nodules were evaluated by US, EI, and ARFI examinations in this study. Three blinded readers scored the likelihood of malignancy for 4 datasets (ie, US alone, US and EI, US and virtual touch tissue imaging [VTI], and US and virtual touch tissue quantification [VTQ]). The diagnostic performances of 4 datasets in differentiating malignant from benign thyroid nodules were evaluated. The decision-making changes for FNA recommendation in the indeterminate nodules or the probably benign nodules on conventional US were evaluated after review of elastography. The diagnostic performance in terms of area under the ROC curve did not show any change after adding EI, VTI, or VTQ for analysis; and no differences were found among different readers; however, the specificity and positive predictive value (PPV) improved significantly after adding VTI or VTQ for analysis in the senior reader. For the indeterminate nodules on US that were pathologically benign, VTQ made correct decision-making changes from FNA biopsy to follow-up in a mean of 82.6% nodules, which was significantly higher than those achieved by EI (46.8%) and VTI (54.4%) (both P < 0.05). With regard to the probably benign nodules on US that were pathologically malignant, EI made the highest correct decision-making change from follow-up to FNA biopsy in a mean of 62.6% nodules (compared with 41.5% on VTQ, P < 0.05). The results indicated that ARFI increases the specificity and PPV in diagnosing thyroid nodules. US combined VTQ might be helpful in reducing unnecessary FNA for indeterminate nodules on US whereas US combined EI is useful to detect the false negative nodules that are probably benign on conventional US.

Parametric imaging with contrast-enhanced ultrasound: usefulness for characterization of dynamic effects of microvascularization for hepatocellular carcinoma and focal nodular hyperplasia.

OBJECTIVE To evaluate whether parametric imaging with contrast-enhanced ultrasound (CEUS) is equal to experienced radiologists after review of CEUS in differentiating hepatocellular carcinoma (HCC) from focal nodular hyperplasia (FNH). METHODS An image processing software was used to quantitatively analyze the CEUS clips of 30 HCCs (mean diameter, 3.4±0.9 cm; range, 1.8-5.0 cm) and 30 FNHs (mean diameter, 3.0±1.1 cm; range, 1.1-5.0 cm). Low mechanical index contrast specific imaging modes and contrast agent of SonoVue® were applied for CEUS. Fourteen HCCs were pathologically diagnosed and 16 were clinically diagnosed, whereas all the FNHs were confirmed by pathological examination. Quantitative parameters of HCC and FNH were compared. The diagnostic performance between parametric imaging and two experienced readers was compared using the receiver operating characteristic (ROC) curve analysis. RESULTS On parametric imaging, the rise time, time to peak and mean transit time for HCC and FNH were 16.7±11.1 s vs. 21.9±9.0 s (P=0.052), 29.9±14.1 s vs. 33.2±11.1 s (P=0.322), 115.0±90.9 s vs. 271.5±147.6 s (P<0.001), respectively. The ROC analysis showed that, for the differentiation between HCC and FNH, the cut-off point for mTT was 107.93 s with the Az value of 0.817 (95% CI: 0.703-0.931), and the Az value was 0.834 (95%CI: 0.728-0.941) for two experienced readers (P=0.417 compared with mTT). The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were 96.7%, 66.7%, 81.7%, 74.4%, and 95.2%, respectively, for parametric imaging, and 86.7%, 76.7%, 81.7%, 78.8%, and 85.2%, respectively, for two experienced readers (all P>0.05 compared with parametric imaging). CONCLUSION Parametric imaging with CEUS is helpful for characterization the typical dynamic effects of microvascularization of HCC and FHH and is equal to experienced readers in the differential diagnosis between HCC and FNH.

Hepatocellular carcinoma after ablation: The imaging follow-up scheme

Percutaneous ablation using thermal or chemical methods has been widely used in the treatment of hepatocellular carcinoma (HCC). Nowadays, contrast-enhanced imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS) are widely used to evaluate local treatment response after ablation therapies. CEUS is gaining increasing attention due to its characteristics including real-time scanning, easy performance, lack of radiation, wide availability, and lack of allergy reactions. Several studies have documented that CEUS is comparable to CT or MRI in evaluating local treatment efficacy within 1 mo of treatment. However, little information is available regarding the role of CEUS in the follow-up assessment after first successful ablation treatment. Zheng et al found that in comparison with contrast-enhanced computed tomography (CECT), the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of CEUS in detecting local tumor progression (LTP) were 67.5%, 97.4%, 81.8%, 94.4% and 92.3%, respectively, and were 77.7%, 92.0%, 92.4%, 76.7% and 84.0%, respectively for the detection of new intrahepatic recurrence. They concluded that the sensitivity of CEUS in detecting LTP and new intrahepatic recurrence after ablation is relatively low in comparison with CECT, and CEUS cannot replace CECT in the follow-up assessment after percutaneous ablation for HCC. These results are meaningful and instructive, and indicated that in the follow-up period, the use of CEUS alone is not sufficient. In this commentary, we discuss the discordance between CT and CEUS, as well as the underlying mechanisms involved. We propose the combined use of CT and CEUS which will reduce false positive and negative results in both modalities. We also discuss future issues, such as an evidence-based ideal imaging follow-up scheme, and a cost-effectiveness analysis of this imaging follow-up scheme.

The diagnostic performance of shear wave speed (SWS) imaging for thyroid nodules with elasticity modulus and SWS measurement

To evaluate the diagnostic performance of a new technique of shear wave speed (SWS) imaging for the diagnosis of thyroid nodule with elasticity modulus and SWS measurement. 322 thyroid nodules in 322 patients (216 benign nodules, 106 malignant nodules) were included in this study. All the nodules received conventional ultrasound (US) and SWS imaging (Aplio500, Toshiba Medical Systems, Japan) before fine-needle aspiration (FNA) and/or surgery. The values of E-max and E-mean with elastic modulus (61.27 ± 36.31 kPa and 31.89 ± 19.11 kPa) or SWS (4.45 ± 1.49 m/s and 3.26 ± 2.71 m/s) in malignant nodules were significantly higher than those in benign lesions (29.18 ± 18.62 kPa and 15.85 ± 6.96 kPa, or 2.98 ± 0.85 m/s and 2.19 ± 0.42 m/s, all P < 0.001). No significant differences in area under the curve (AUC) between the SWS imaging parameters were found (all P > 0.05). In multivariate logistic regression analysis, E-max (m/s) with SWS was identified to be the strongest independent predictor for malignant nodules (odds ratio [OR] = 16.760), followed by poorly-defined margin (OR = 7.792), taller-than-wide shape (OR = 3.160), micro-calcification (OR = 2.422), and E-max (kPa) with elastic modulus (OR = 0.914). The AUC was 0.813 for E-max with SWS (m/s) and 0.796 for E-max with elastic modulus (kPa). With cut-off SWS value of 3.52 m/s in E-max, sensitivity of 69.8%, specificity of 81.5%, and accuracy of 77.6% were achieved. SWS imaging is a valuable tool in predicting thyroid malignancy. E-max with SWS measurement is the strongest independent predictor for thyroid malignancy.