The value of acoustic radiation force impulse (ARFI) in the differential diagnosis of thyroid nodules

Objectives

The aim of this study was to investigate the value of shear wave velocity value (SWV) and shear wave velocity ratio (SWR) in differentiating between malignant and benign thyroid nodules using virtual touch tissue quantification (VTQ) of acoustic radiation force impulse (ARFI) technology.

Methods

The SWV and SWR were analyzed in 155 thyroid nodules in 155 patients (93 benign and 62 malignant) and eighty normal thyroid glands. The diagnostic performance of SWV and SWR were compared.

Results

The mean value of SWV of malignant nodules differed significantly from those of the benign nodules (6.34 ± 2.58 m/s vs. 2.15 ± 0.59 m/s, P < 0.05) and the normal thyroid (1.96 ± 0.31 m/s, P < 0.05). There was no statistically significant difference between the mean value of SWV of benign nodules and normal thyroid (P > 0.05). The mean value of SWR of malignant nodules differed significantly from those of the benign nodules (2.99 ± 1.45 vs. 1.07 ± 0.34, P < 0.05). The sensitivity, specificity, positive predictive values, negative predictive values and accuracy of SWV in differentiating between malignant and benign nodules were 96.80%, 95.70%, 93.75%, 97.80% and 96.13% respectively based on the cutoff point as 2.84 m/s. Those of SWR were 91.90%, 81.70%, 77.03%, 93.83% and 85.83% based on the cutoff point as 1.32. The diagnostic accuracy rate of SWV was statistically higher than that of SWR (P < 0.05).

Conclusion

VTQ of ARFI technology provides the quantitative information of thyroid tissue elasticity and has high accuracy rate in differentiating between malignant and benign nodules. It is a useful complement for conventional ultrasonography.     

二维超声与声触诊组织成像对甲状腺良恶性结节诊断的对比研究

目的 探讨二维超声和声脉冲辐射力声触诊组织成像（virtual touch tissue imaging,VTI）在鉴别甲状腺良恶性结节的价值.方法 对128例甲状腺结节患者的136个结节分析,所有患者接受二维超声和VTI检查,绘制两种方法诊断甲状腺恶性结节的ROC曲线,比较其诊断价值.结果 构建ROC曲线获得两种方法的曲线下的面积为0.757、0.884,VTI成像的曲线下面积明显大于二维超声（P＜0.004）;以≥4分、≥Ⅳ级分别为良、恶性肿块二维超声和VTI的最佳截断点,其诊断甲状腺恶性结节的敏感性、特异性和准确性分别为62.8％、81.3％、76.4％和86.3％、83.8％、83.8％.结论 声触诊组织成像对甲状腺良恶性结节的诊断有一定价值.     

超声助力式弹性成像和声触诊组织成像量化技术对浅表软组织肿物诊断的价值

目的探讨超声助力式弹性成像(EI)和声触诊组织成像量化(VTQ)技术对浅表软组织肿物的诊断价值。方法回顾性收集经活检或手术病理证实且常规超声诊断有浅表软组织肿物的病人50例,共64个肿物。采用常规超声测量肿物大小、纵横比并观察其形态、边界、内部回声等指标,彩色多普勒观察血流信号,采用助力式EI获得肿物的弹性影像,并进行半定量评分,采用VTQ技术测量剪切波速度(SWV)。以病理结果为金标准,计算常规超声、EI评分和VTQ技术对良恶性浅表软组织肿物的诊断效能。采用Wilcoxon秩和检验比较良恶性肿物间的SWV,绘制SWV的受试者操作特征(ROC)曲线,计算ROC曲线下面积(AUC)。结果64个肿物中,病理诊断良性肿物51个,恶性肿物13个。常规超声诊断浅表软组织肿物良恶性的敏感度、特异度、准确度分别为76.9%(10/13)、90.2%(46/51)、87.5%(56/64),EI诊断的敏感度、特异度、准确度分别为76.9%(10/13)、88.2%(45/51)、85.9%(55/64),EI联合常规超声诊断的敏感度、特异度及准确度分别为84.6%(11/13)、94.1%(48/51)、92.2%(59/64)。VTQ检测恶性肿物的SWV高于良性肿物(P<0.05)。取SWV值2.995 m/s作为诊断阈值时,VTQ鉴别诊断肿物良恶性的AUC为0.983,其敏感度、特异度分别为92.3%、90.2%。结论EI弹性评分可半定量反映肿物组织的硬度信息,VTQ可定量评估肿物组织硬度弹性特征,两种成像模式对鉴别诊断浅表软组织肿物良恶性有一定价值。     

声触诊组织定量技术在低温条件下兔肾改变评价中应用研究

目的探讨应用声触诊组织定量(VTQ)技术观察低温条件下兔肾改变的价值。方法建立-20℃~-25℃兔低温模型,分别于低温前(T_0)、低温2 h(T_1)、低温4 h(T_2)、低温6 h(T_3)、低温8 h(T_4)5个时间点对肾进行二维超声与VTQ检查,观察各个时间点肾回声、长径、宽径、厚度以及肾的剪切波速度(SWV)。结果各时间点二维图像比较,肾皮质回声未发生明显改变,各时间点肾长径、宽径、厚度、体积比较,差异也均无统计学意义(P>0.05)。T_1~T_4各时间点兔肾SWV值随时间变化逐渐升高,与T_0时间点比较,差异均有统计学意义(P<0.05)。结论 VTQ技术可反映低温条件下兔肾硬度变化,更早地为临床提供有用的信息。     

The application of Virtual Touch tissue quantification (VTQ) in diagnosis of thyroid lesions: A preliminary study

Objectives

Virtual Touch tissue quantification (VTQ) is a quantified ultrasound (US) acoustic radiation force impulse (ARFI) imaging method that provides numerical measurements (wave-velocity values) of tissue stiffness. The purpose of this study was to detect whether VTQ could be applied to differentiate between benign and malignant thyroid lesions.

Methods

Healthy subjects’ thyroid tissue and thyroid lesions were examined by VTQ to analyze their elasticity after conventional ultrasound. All the thyroid lesions were analyzed pathologically after surgery and correlated the VTQ values with the pathological results.

Results

The VTQ value of healthy thyroid tissue, the benign lesions, and the malignant lesions were 1.69 ± 0.41 m/s, 2.03 ± 0.42 m/s, and 3.10 ± 1.08 m/s, respectively. The VTQ value of the malignant lesions was higher than that of the healthy thyroid tissue and the benign lesions (both p < 0.001). The VTQ value of the benign lesions was higher than that of the healthy thyroid tissue (p < 0.001). With a cutoff value of 2.42 m/s, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for differentiating between the benign and the malignancy lesions were 80.00%, 89.23%, 87.05%, 69.56%, and 93.54%, respectively.

Conclusions

VTQ could provide quantitative elasticity measurements, which might play an important role in differentiating between benign and malignant thyroid lesions.     

Normal breast tissue stiffness measured by a new ultrasound technique: Virtual touch tissue imaging quantification (VTIQ)

Objective

To evaluate normal breast tissue stiffness with virtual touch tissue imaging quantification (VTIQ) using prospectively collected data.

Materials and Methods

B-mode ultrasound and VTIQ were performed in 132 breasts in 97 women. Mean values of VTIQ for parenchyma and fatty tissue were compared between those measured in healthy breasts and in the surrounding of histologically proven benign and malignant breast lesions. Moreover we reviewed VTIQ values according to breast density measured by the American College of Radiology (ACR) categories. In addition we analyzed re-test reliability of VTIQ.

Results

In 132 breasts the mean VTIQ values in parenchyma were significantly higher than in fatty tissue (3.23 m/s ± 0.74 versus 2.5 m/s ± 0.61; p < 0.0001). In healthy breasts as well as in the surrounding of a benign or malignant lesions the VTIQ values of parenchyma were similar (p = 0.12). In fatty tissue, small differences between mean VTIQ values of 2.25 m/s ± 0.51, 2.52 m/s ± 0.48 and 2.65 m/s ± 0.71 (p = 0.01) in the respective groups were observed. The comparison of mean VTIQ values of parenchyma and fatty tissue in more and less dense breasts (ACR 1 + 2 versus ACR 3 + 4 breasts) also yielded no statistically significant difference. The re-test reliability of VTIQ assessed with three independent measurements was moderate (interclass-correlation of 0.52 (p < 0.0001)).

Conclusion

VTIQ is a reliable method for measuring the stiffness of breast tissue. We propose standard values for healthy parenchyma and fatty tissues independent of the surrounding tissue or the ACR category.     

声触诊组织量化技术对肝纤维化的诊断价值

目的 评估声触诊组织量化（VTQ）技术对肝纤维化的诊断价值.方法 选取2011年6月~2012年12月来我院就诊的慢性肝炎患者（慢性肝炎组）60例、肝硬化患者（肝硬化组）45例及健康体检者（健康对照组）25例,利用VTQ技术测定右肝感兴趣区肝脏横向剪切波速度（SWV）;慢性肝炎患者同期行肝穿刺活检病理检查,分析SWV与肝纤维化程度的相关性,采用受试者工作特征（ROC）曲线,评价VTQ技术诊断肝纤维化的准确性.结果 健康对照组、慢性肝炎组及肝硬化组肝脏SWV分别为（2.0±0.2）m/s、（2.3±0.4）m/s 和（3.1±0.5）m/s,3者间具有显著性差异（P＜0.05）.随着肝纤维化程度加深,肝脏SWV增高,SWV值与肝纤维化分期呈正相关,相关系数为0.73（P〈0.05）;诊断≥S2及≥S3的ROC曲线下面积为0.94、0.92,诊断的临界值为1.36m/s、1.69m/s,灵敏性、特异性分别为0.88、0.88,0.92、0.76.结论 VTQ技术对肝纤维化具有较高的诊断价值.     

Combination of elastography and tissue quantification using the acoustic radiation force impulse (ARFI) technology for differential diagnosis of breast masses

Purpose

We evaluated the diagnostic performance of elastography and tissue quantification using acoustic radiation force impulse (ARFI) technology for differential diagnosis of breast masses.

Materials and methods

There were 161 mass lesions. First, lesion correspondence on ARFI elastographic images to those on the B-mode images was evaluated: no findings on ARFI images (pattern 1), lesions that were bright inside (pattern 2), lesions that were dark inside (pattern 4), lesions that contained both bright and dark areas (pattern 3). In addition, pattern 4 was subdivided into 4a (dark area same as B-mode lesion) and 4b (dark area larger than lesion). Next, shear wave velocity (SWV) was measured using virtual touch tissue quantification.

Results

There were 13 pattern 1 lesions and five pattern 2 lesions; all of these lesions were benign, whereas all pattern 4b lesions (n?=?43) were malignant. When the value of 3.59?m/s was chosen as the cutoff value, the combination of elastography and tissue quantification showed 91?% (83?C91) sensitivity, 93?% (65?C70) specificity, and 92?% (148?C161) accuracy.

Conclusion

The combination of elastography and tissue quantification is thought to be a promising ultrasound technique for differential diagnosis of breast-mass lesions.     

Diagnostic utility of real-time ultrasound elastography for prediction of malignancy in solid thyroid nodules

Aim of the work

To study the diagnostic utility of real-time ultrasound elastography (USE) in predicting malignancy in thyroid nodules.

Materials and methods

Forty-five patients with solitary solid thyroid nodules were included in this study. The thyroid nodules were examined by B-mode ultrasound, color flow Doppler ultrasound, and real-time ultrasound elastography (USE). The final diagnosis was obtained from histopathological findings. Tissue stiffness on USE was scored from 1 (low stiffness over the entire nodule) to 6 (high stiffness over the entire nodule and surrounding tissue).

Results

Twenty-eight (62.2%) patients had a final diagnosis of malignancy based on histopathological evidence of malignant thyroid nodules, while 17 (37.8%) were diagnosed as benign nodules. Anteroposterior/transverse (AP/T) diameter more than 1 cm, ill-defined margins and spot micro calcifications were the most predictive conventional ultrasound patterns of malignancy. Elasticity score of 4–6 was highly predictive of malignancy (P < 0.0001), with a sensitivity of 89.3%, a specificity of 88.2% and an accuracy of 88.9%.

Conclusion

Ultrasound elastography is an accurate non invasive tool for evaluating thyroid nodules. It has more appropriate value in the differential diagnosis of thyroid malignancy and enhances the diagnostic assurance of ultrasonographers.     

高频超声及声触诊组织量化技术对男性肩袖损伤患者冈上肌腱的评价

目的:应用高频超声及声触诊组织量化技术(VTIQ)评价男性肩袖损伤患者冈上肌腱的变化.方法:收集50例确诊的肩袖损伤男性患者,分为A组(35～59岁)28例和B组(≥60岁)22例.患者均行常规检查及VTIQ检查,测量冈上肌腱的厚度及其近端、远端的剪切波速度(SWV).结果:常规检查示B组双侧冈上肌腱厚度均大于A组(均...     

Role of combined grey scale US and US tissue elastography in differentiating solid thyroid nodules

Background

Ultrasonographic (US) examination is an accurate method for detecting thyroid nodules, but its use in differentiating between benign and malignant thyroid nodules is relatively low. US elastography has been applied to study the hardness/elasticity of nodules to differentiate malignant from benign lesions thus deviating a significant group of patients from unnecessary FNAB.

Objectives

The aim of the study is to evaluate the validity of combined grey scale US and tissue elastography in differentiating benign form malignant solid thyroid nodules.

Methods

The study included 46 selected patients with solid thyroid nodules according to our inclusion and exclusion criteria. The patients underwent surgery for compressive symptoms or suspicion of malignancy on FNA cytology. US features and tissue elastography were scored according to the Rago criteria (1).

Results

On US elastography: all the 31 cases with a final diagnosis of benign nodule had a score of 1–3, while 14 of 15 (94.1%) with a final diagnosis of carcinoma had a score of 4–5, with a sensitivity of 93.3%, a specificity of 100% and an accuracy of 97.8%. Combined US and elastography reveals that hypoechogenicity/score 4–5 was most predictive of malignancy with sensitivity 80% and specificity 100%; and accuracy 93.4%.

Conclusions

US elastography seems to have great potential as a new tool for differentiating solid thyroid nodules and for recommending FNAC. Combined grey scale US features and US elastography added no significant value when compared with US elastography alone. Further prospective studies are needed.     

Treatment response assessment of radiofrequency ablation for hepatocellular carcinoma: usefulness of virtual CT sonography with magnetic navigation

Purpose

Virtual CT sonography using magnetic navigation provides cross sectional images of CT volume data corresponding to the angle of the transducer in the magnetic field in real-time. The purpose of this study was to clarify the value of this virtual CT sonography for treatment response of radiofrequency ablation for hepatocellular carcinoma.

Patients and methods

Sixty-one patients with 88 HCCs measuring 0.5–1.3 cm (mean ± SD, 1.0 ± 0.3 cm) were treated by radiofrequency ablation. For early treatment response, dynamic CT was performed 1–5 days (median, 2 days). We compared early treatment response between axial CT images and multi-angle CT images using virtual CT sonography.

Results

Residual tumor stains on axial CT images and multi-angle CT images were detected in 11.4% (10/88) and 13.6% (12/88) after the first session of RFA, respectively (P = 0.65). Two patients were diagnosed as showing hyperemia enhancement after the initial radiofrequency ablation on axial CT images and showed local tumor progression shortly because of unnoticed residual tumors. Only virtual CT sonography with magnetic navigation retrospectively showed the residual tumor as circular enhancement. In safety margin analysis, 10 patients were excluded because of residual tumors. The safety margin more than 5 mm by virtual CT sonographic images and transverse CT images were determined in 71.8% (56/78) and 82.1% (64/78), respectively (P = 0.13). The safety margin should be overestimated on axial CT images in 8 nodules.

Conclusion

Virtual CT sonography with magnetic navigation was useful in evaluating the treatment response of radiofrequency ablation therapy for hepatocellular carcinoma.     

两种声脉冲辐射力成像技术与慢性肾脏损害程度的相关性研究

目的研究两种声脉冲辐射力成像技术(ARFI)与慢性肾脏损害程度的相关性。方法选取61例慢性肾病患者作为肾病组(其中17例为IgA肾病患者),54名健康成年作为对照组;应用声触诊组织成像技术(VTI)联合灰阶图像定量分析软件与声触诊组织定量分析技术(VTQ),分别测定两组受检者肾实质灰阶值与剪切波(SWV),评估其与慢性肾病肾小球滤过率(GFR)分期及其与IgA肾病Lee病理分级之间的相关性。结果 (1)肾病组患者肾实质的SWV值为(2.83±0.67)m/s,对照组患者肾实质的SWV值为(3.56±0.45)m/s;肾病组患者肾实质的灰阶值为(88.46±17.42)dB,对照组患者肾实质的灰阶值为(64.04±11.00)dB;(2)慢性肾病患者肾实质灰阶值与GFR分期呈正相关性(r=0.72,P<0.05),其SWV值与GFR分期呈负相关性(r=-0.56,P<0.05);IgA肾病患者的肾实质灰阶值与其Lee病理分级呈正相关(r=0.71,P<0.05),其SWV值与Lee病理分级呈负相关(r=-0.79,P<0.05)。结论 VTQ技术测得的SWV值以及VTI技术结合灰阶图像分析软件所测得的灰阶值均可定量反映慢性肾脏损害程度。     

“Calvarial Butterfly” new multidetector computed tomography (MDCT) virtual osteoscopic (VO) fingerprint for identification

Purpose

The battle between criminal associations and law enforcement still rages to this day, providing ever more elusive ways to mask away the characteristics which will lead criminals, eventually, to justice. So we tried to find an easy way using one of the MDCT applications namely “virtual osteoscopy” to create a new internal “fingerprint” that could not be manipulated by any means.

Methods and material

Virtual osteoscopic evaluation (post-processing technique) of the calvarial bones of 1120 patients was carried out using the available software “Syngo” from Siemens Medical Technology – Erlangen – Germany; following routine MDCT evaluation of the brain due to different complaints. The generated images were reviewed, analyzed and the results were tabulated. Thorough evaluation of the axial cuts regarding any abnormalities including skull features, skull vault thickness, paranasal sinuses, brain lesions or normal variants which may be kept as a reference hand in hand with the virtual osteoscopic findings of the Calvarial Butterfly.

Results

The generated data were tabulated regarding the patterns of the generated Butterfly-like structure representing the external features of the diploic space marrow cavity at the occipital protuberance level. From the examined patients it was shown that each individual had a unique Butterfly-like structure having distinct external features, patterns as well as calculated volumes.

Conclusion

The 3D virtual endoscopic models with the generated Butterfly-like appearance (i.e. virtual osteoscopy) at the occipital region will play a major role in the cases of identification and anthropology in both in vivo and in vitro cases and will solve a lot of forensic medicine mysteries.     

Microwave ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma undetectable by conventional ultrasonography

Objectives

To evaluate the efficiency and feasibility of microwave (MW) ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma (HCC) undetectable by conventional ultrasonography.

Methods

18 patients with 18 HCC nodules (undetectable on conventional US but detectable by intravenous contrast-enhanced CT or MRI) were enrolled in this study. Before MW ablation, US images and MRI or CT images were synchronized using the internal markers at the best timing of the inspiration. Thereafter, MW ablation was performed under real-time virtual navigation system guidance. Therapeutic efficacy was assessed by the result of contrast-enhanced imagings after the treatment.

Results

The target HCC nodules could be detected with fusion images in all patients. The time required for image fusion was 8–30 min (mean, 13.3 ± 5.7 min). 17 nodules were successfully ablated according to the contrast enhanced imagings 1 month after ablation. The technique effectiveness rate was 94.44% (17/18). The follow-up time was 3–12 months (median, 6 months) in our study. No severe complications occurred. No local recurrence was observed in any patients.

Conclusions

MW ablation assisted by a real-time virtual navigation system is a feasible and efficient treatment of patients with HCC undetectable by conventional ultrasonography.     

Comparison analysis between conventional ultrasonography and ultrasound elastography of thyroid nodules

Objective

To compare the effectiveness of conventional ultrasonography and ultrasound elastography in differential diagnosis of thyroid nodular diseases.

Methods

244 patients with 291 thyroid nodules were examined by ultrasonography and ultrasound elastography respectively; the examination results were compared against pathological findings to determine the effectiveness of these two examination methods.

Results

The sensitivity and positive predictive value of conventional ultrasonography is higher than those of ultrasound elastography, but its specificity, accuracy, and negative predictive value is lower than those of the later.

Conclusions

Ultrasound elastography is superior to conventional ultrasonography in differential diagnosis of thyroid nodules. However, ultrasonography is the basis of examination; only on this basis, an additional ultrasound elastography examination could greatly improve the diagnostic rate of thyroid nodular diseases.     

Can real-time ultrasound elastography using the color score and strain ratio differentiate between benign and malignant solitary thyroid nodules?

Background

Solitary thyroid nodule may represent a multitude of thyroid disorders; therefore, detection of whether these nodules are benign or malignant is crucial for patient’s triage.

Objective

To evaluate the diagnostic performance of the latest generation of real-time ultrasound elastography (USE) in differentiation between benign and malignant solitary thyroid nodules.

Materials and methods

Thirty consecutive patients who were referred for surgical treatment were prospectively examined by real-time USE. Tissue stiffness on real-time USE was determined with light compression using the standard elastography color scoring system according to Rago criteria ranging from 1 (low stiffness over the entire nodule) to 5 (high stiffness over the entire nodule and surrounding tissue). The strain ratio (normal tissue to lesion strain ratio) was calculated. The histopathological examination of these resected nodules was used as the diagnostic standard of reference.

Results

Scores of 1 and 2 with Rago criteria were highly significant seen in benign nodules, whereas, scores of 4 and 5 with Rago criteria were highly significant seen in malignant nodules (p < 0.001) with a sensitivity, specificity and diagnostic accuracy of 78.6%, 78.9% and 78.8% respectively. Additionally, the best strain ratio cut-off value for discrimination between benign and malignant nodules by using receiver operating characteristic analysis was 2.20 (area under the curve of 0.861; p value <0.001) with a consequential sensitivity, specificity and diagnostic accuracy of 85.7%, 90.5% and 88.6% respectively.

Conclusion

Both the color score and the strain ratio are higher in malignant solitary thyroid nodules than those in benign ones. Consequently, real-time USE can be used for the differentiation of benign and malignant solitary thyroid nodules. Eventually, this reduces the number of superfluous surgical procedures on benign thyroid nodules.     

Acoustic Radiation Force Impulse (ARFI) ultrasound imaging of solid focal liver lesions

Objective

The aim of this paper was to evaluate the application of ARFI ultrasound imaging and its potential value for characterizing focal solid liver lesions.

Materials and methods

In this multicentric prospective study, over a total non-consecutive period of four months, all patients underwent ARFI US examination. Two independent operators performed 5 measurements per each lesion and 2 measurements in the surrounding liver. According to the definitive diagnosis, a mean velocity value and standard deviations were obtained in each type of focal solid lesion, compared by using t-test, and the inter-operator evaluation was performed by using the Student's t-test. A comparison between the total mean values of each type of lesion and the mean value of the parenchyma was performed.

Results

40 lesions were evaluated and a total of 400 measurements were obtained. The lesions were: 6/40(15%) hepatocellular carcinomas, 7/40(17.5%) hemangiomas, 5/40(12.5%) adenomas, 9/40(22.5%) metastases and 13/40(32.5%) focal nodular hyperplasias. The total mean values obtained were: 2.17 m/s in HCCs, 2.30 m/s in hemangiomas, 1.25 m/s in adenomas, 2.87 m/s in metastases and 2.75 m/s in FNHs. The inter-operator evaluation resulted non-statistically different (p > 0.05). A significant difference (p < 0.05) was always found by comparing adenomas to the other lesions. 160 measurements were obtained in the surrounding parenchyma, with a no significant difference between values measured in adenomas and in the surrounding liver.

Conclusions

ARFI technology with Virtual Touch tissue quantification could non-invasively provide significant complementary information regarding the tissue stiffness, useful for the differential diagnosis of focal solid liver lesions.     

Efficacy of thyroid ultrasound elastography in differential diagnosis of small thyroid nodules

Objective

To explore the efficacy of thyroid ultrasound (US) elastography in differential diagnosis of small thyroid nodules.

Methods

This HIPAA-compliant study was approved by the Institutional Review Board and all patients provided written informed consent. Thirty-five patients with 38 small thyroid nodules as seen on transverse ultrasound image formed our study population. An US examination and a separate thyroid elastography examination with pulsation from the carotid artery used as the compression source were performed before fine-needle aspiration. Baseband US data were acquired for off-line elastography processing, where a semi-quantitative index for each nodule was calculated. The Kruskal–Wallis nonparametric rank sum test was used to assess equality of population means among the different types of thyroid nodules. Maximum likelihood estimation of the curve parameters for a binomial receiver operating characteristic (ROC) curve was performed.

Results

Elasticity contrast index calculated with elastography was effective in distinguishing between small papillary thyroid carcinomas (PTMC, n = 8) and other lesions (n = 30) in small thyroid nodules (p = 0.0036). The area under the ROC curve for diagnosing PTMCs was 0.812 with a 95% confidence interval of 0.653–0.920. The cut-off value of ECI of 3.6 led to a sensitivity of 100% and a specificity of 60% for detecting PTMCs.

Conclusion

Noninvasive evaluation of small thyroid nodules is possible using thyroid US elastography with in vivo compression to pick out the most suspicious thyroid nodules for fine-needle aspiration (FNA) and avoid FNA in benign nodules.     

The utility of acoustic radiation force impulse imaging in diagnosing acute appendicitis and staging its severity

PURPOSE

The aim of this study was to investigate the feasibility of using acoustic radiation force impulse (ARFI) imaging to diagnose acute appendicitis.

METHODS

Abdominal ultrasonography (US) and ARFI imaging were performed in 53 patients that presented with right lower quadrant pain, and the results were compared with those obtained in 52 healthy subjects. Qualitative evaluation of the patients was conducted by Virtual Touch™ tissue imaging (VTI), while quantitative evaluation was performed by Virtual Touch™ tissue quantification (VTQ) measuring the shear wave velocity (SWV). The severity of appendix inflammation was observed and rated using ARFI imaging in patients diagnosed with acute appendicitis. Alvarado scores were determined for all patients presenting with right lower quadrant pain. All patients diagnosed with appendicitis received appendectomies. The sensitivity and specificity of ARFI imaging relative to US was determined upon confirming the diagnosis of acute appendicitis via histopathological analysis.

RESULTS

The Alvarado score had a sensitivity and specificity of 70.8% and 20%, respectively, in detecting acute appendicitis. Abdominal US had 83.3% sensitivity and 80% specificity, while ARFI imaging had 100% sensitivity and 98% specificity, in diagnosing acute appendicitis. The median SWV value was 1.11 m/s (range, 0.6–1.56 m/s) for healthy appendix and 3.07 m/s (range, 1.37–4.78 m/s) for acute appendicitis.

CONCLUSION

ARFI imaging may be useful in guiding the clinical management of acute appendicitis, by helping its diagnosis and determining the severity of appendix inflammation.Acute appendicitis is among the most common causes of acute abdominal pain (1, 2). Despite significant improvements in medical technology, the diagnosis of appendicitis is typically based on clinical findings, resulting in a false-positive rate of 8%–30% (3–6). It is widely understood that ultrasonography (US) and computed tomography (CT) are effective imaging modalities in the detection of appendicitis, although certain limitations to both techniques are apparent. Namely, visualization of the appendix is impossible in nearly 15% of healthy people, and among patients with suspected appendicitis, detection of tip appendicitis or periappendiceal inflammation is relatively poor (7–11). Previous studies employing graded-compression US reported widely variable rates of diagnostic accuracy, with sensitivity ranging from 44% to 100% and specificity ranging from 47% to 99% (12).The use of scoring systems enhances the sensitivity and specificity of the available imaging modalities in the diagnosis of acute appendicitis. In addition, scoring systems aim to minimize the risk of clinical complications and avoid the costs associated with delayed diagnosis or unnecessary appendectomies. Among current scoring systems, the Alvarado system has proven to be a cost-effective method of classifying patients according to acute appendicitis risk. The efficacy of the Alvarado system has been demonstrated in clinical studies, which identified a diagnostic cutoff score of 4–6 for acute appendicitis. Appendectomy is strongly indicated among patients with a score of ≥7, while patients scoring 5 or 6 should receive follow-up care (13). However, the sensitivity and specificity of the Alvarado system do not exceed 90%.The mechanical properties of a tissue can be determined using acoustic radiation force impulse (ARFI) imaging. The technique of ARFI imaging comprises two different methods: Virtual Touch™ tissue imaging (VTI) and Virtual Touch™ tissue quantification (VTQ). VTI provides a qualitative map (elastogram) of relative stiffness for a user-defined region of interest. Using this method, stiff tissue may be differentiated from soft tissue even if it is appearing isoechoic using conventional US imaging. VTQ is a modified application of US ARFI imaging that generates shear wave velocity (SWV) corresponding to tissue stiffness. VTQ has been used to determine tissue elasticity of a variety of organ systems, inflammatory processes, congestion, and fibrosis. ARFI imaging capability is an integral component of the existing US equipment and may be performed as a part of standard US procedures. SWV can be quantified through the application of standard B-mode US. Recent data demonstrated a strong correlation between ARFI imaging and hepatic fibrosis staging (6–8), and investigations of renal tumor diagnosis have also been conducted (14–17). The diagnosis of acute appendicitis by quantitative real-time elastography has been previously reported, although clinical data demonstrating the efficacy of the technique in a substantial number of patients is lacking (18). The aim of the present study was to evaluate the efficacy of ARFI imaging in diagnosis of acute appendicitis.