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The Diagnostic Value of 3D Power Doppler Ultrasound Combined With VOCAL in the Vascular Distribution of Breast Masses
ARTICLE IN PRESS
Original Investigation
The diagnostic value of 3D power Doppler ultrasound combined with VOCAL in the vascular distribution of breast masses Huizhu Wang, MDy, Bing Yan, PhDy, Lifang Yue, MD, Mingyu He, PhD, Yuehua Liu, MD, Hezhou Li, MD Abbreviations MG Gray Mean MP Power Mean VFI vascular flow index AUC Under the area of the ROC curve 3D-PDA three-dimensional power Doppler Ultrasound VOCAL Virtual Organ-aided Analysis BI-RADS Breast imaging reporting and data System
Rationale and Objectives: This study uses a three-dimensional energy Doppler technique combined with the Virtual Organ Computer-aided Analysis (VOCAL) method in order to determine the diagnostic threshold of blood flow index in breast tumors to provide a reference for evaluation and treatment options. Materials and methods: We collected 322 solid lesions which had been operated. Each lesion met the definite pathological diagnosis; collected lesions included 262 cases of benign lesions and 60 cases of malignant lesions. All examinations were performed by using GE LOGIQ E9 with VOCAL software. Volume and four distinct vascular indices of gray mean (MG), power mean, ratio (R), and vascular flow index (VFI) were calculated by using the VOCAL software. Sampling and calculation were repeated three times and the mean value was calculated. Results: The average age and power of the malignant group were greater than those of the benign group, ie p < .01 which had significant differences. The gray mean of the malignant group was lower than that of the benign group, ie p > .05 which had no significant differences between benign and malignant groups. The ratio, vascular flow index and volume had significant differences, i.e. p < .01. The area under the receiver operating characteristic curve (AUC) were 0.864, 0.830, 0.800, 0.758, and 0.764 for age, power, ratio, vascular flow index, and volume, respectively. The research indicators were higher than 50% of the curve showing their diagnostic value. The cut-off points of age, power, ratio, vascular flow index, and volume were 37.5, 26.56, 0.031, 0.846, and 1.75, respectively. Their corresponding sensitivity were 93.3%, 75%, 81.7%, 68.3%, 63.3%, and the specificity were 68.7%, 81%, 70.2%, 75.6%, and 81.7%, respectively. Comparison of vascular indices combined with the Breast imaging reporting and data System (BI-RADS) score and simple BI-RADS method, the AUC of power + BI-RADS, ratio + BI-RADS, VFI + BI-RADS, and BI-RADS alone are 0.928, 0.903, 0.895, and 0.796, respectively, which were higher than 50% of the curve. Sensitivity was 81.7%, 80%, 88.3%, 86.7%, and specificity was 88.5%, 85.5%, 77.1%, 69.5%, respectively. The power + BI-RADS method has the highest AUC among these three methods. Conclusions: Quantitative measurement of blood flow and blood vessel distribution in breast tumors by three-dimensional power Doppler ultrasound combined with the VOCAL method is more accurate and sensitive than the traditional two-dimensional ultrasound. And this method has potential promising applications in many current active research areas, such as the studies of random distribution of intratumoral blood vessels or the normalization of tumor blood vessels. Three-dimensional power Doppler ultrasound combined with the VOCAL method provides a new approach to achieving accurate judgments and the method evaluates the curative effect in breast cancer patients. Key Words: VOCAL; 3-dimensional; Power Doppler; Ultrasound; Breast; BI-RADS. © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Acad Radiol 2019; &:1–6 From the Department of Ultrasound, the third affiliated hospital of Zhengzhou University, No. 7 Kangfu Qian Street, Erqi District, Zhengzhou, 450052, China (H.W., L.Y., H.L.); Henan Key Laboratory of Digestive Organ Transplantation, the first affiliated hospital of Zhengzhou University, Zhengzhou, China (B.Y.); Center for ultrasound molecular imaging and therapeutics, School of medicine, University of Pittsburgh, Pittsburgh, PA, USA (M.H.); Department of Obstetrics and Gynecology, the third affiliated hospital of Zhengzhou University, Zhengzhou, China (Y.L.). Received January 19, 2019; revised February 27, 2019; accepted February 28, 2019. Declare of interests: No author declared competing interests. The authors declare that all data supporting the findings of this study are available within the article and its additional files. The corresponding author had full access to all data and final responsibility for the decision to submit the manuscript for publication. Address correspondence to: H.L. e-mail: [email protected] y These authors contributed equally to this work. © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.acra.2019.02.023
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ARTICLE IN PRESS WANG ET AL
INTRODUCTION
T
he incidence of breast cancer is increasing yearly, early diagnosis and treatment deliver the best prognosis. It’s reported that breast cancer cells produce vascular endothelial growth factor, which can stimulate the growth of blood vessels accompanied by the morphological changes (1,2). The malignant vessel differs from normal ones, which include uneven thickness, increased density, and irregular serpentine courses. Using the vascular 3D ultrasound imaging technology, the dilated afferent artery, and the abundant heterogeneous interior vasculature with regard to organization and structure malformation, and even arteriovenogenesis, are usually observed in malignant tumors by visualizing the internal vasculature. Whereas, the peripheral structures of blood vessels near the benign counterpart usually show regular and normal vessel morphology. Three-dimensional power Doppler Ultrasound (3D-PDA) is a newly developed technology combing the three-dimensional ultrasound with power Doppler. 3D-PDA provides clear and comprehensive sonogram images, tumor-related blood flow information, low-velocity blood flow change data, tracks the construction and distribution of blood vessels in tumors, as well as improves diagnostic accuracy of breast malignant tumors (3,4). Virtual Organ Computer-aided Analysis (VOCAL) software is the computer-guided virtual histology analysis, which can calculate the gray mean (MG) (average gray in interesting area), power mean (average brightness value of color voxels), ratio (proportion of color voxels in interesting area), and vascular flow index ([VFI], power mean multiples by ratio) to quantify the distribution of blood vessels in breast tumors. VOCAL was originated from 3D-view and 4D-view software installed on Krez machine which was acquired by GE company and was also developed and installed on the GE LOGIQ from 2007. At present, the studies of vascular distribution in breast masses working to differentiate malignant tumors from benign tumors are hot topics attracting interest from researchers and clinicians, while most studies are qualitative evaluation and lack quantitative evaluation. In this study, three-dimensional power Doppler technique combining with VOCAL method (5) was used to determine the diagnostic threshold of blood flow index in breast tumors and provide a reference for evaluation and treatment options. MATERIALS AND METHODS All examinations were performed by using GE LOGIQ E9 with a volumetric linear probe. This transducer is a broadbased linear-array probe with a frequency of 612 MHz, it has 50 mm scanning width and a sweep angle of 529° to allow for the performance of a 3D volume scan. Patients took off their upper outer garment, lay in a supine position, and place their arms over the head. During the performed 3D volume scan, all patients were asked to hold their breath approximately 20 seconds. The following power Doppler 2
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settings were used to standardize our assessment of breast vascularization: (frequency 6.3; gain 19.0; pulse repetition frequency, 0.8 KHz; wall motion filter, 100; line density/frame average 3/6; sample volume/package size 4/14; artifact on 100%). After the mass was localized in the 2D view, 3D static power Doppler scanning was performed by using the widest scanning angle (30°) covering the whole breast mass. After the examination, the VOCAL software was used to obtain the volume data. The rotation angle was set to 30°and six different consecutive mass sections were obtained. The volume and three vascular indices of gray mean (MG), power mean (MP), ratio (R) and vascular flow index (VFI) were calculated using the VOCAL software. Sampling and calculation were repeated three times and the mean value was calculated. Each data group was completed by two ultrasound doctors who had 10+ years of ultrasound examination experience. Data Analysis
IBM SPSS software (24.0 version, Armonk, NY) was used for statistical analysis of the data. The data that follow normal distribution are compared by Independent-Sample t Test, and the data that follow non-normal distribution are compared by Nonparametric Tests. Multivariate analysis was performed by logistic regression analysis. Age, mass volume, vascular indices, simple Breast imaging reporting and data System (BI-RADS) score, and BI-RADS method combing with vascular indices were evaluated by the receiver operating characteristic curve (ROC). The ROC was used to determine the diagnostic efficiency. A p < .05 was considered statistically significant.
RESULTS A total of 222 patients (age range, 1872 years; mean age, 37.0 years) were treated in our hospital between May 2016November 2017. The median age of the benign group is 33.8 (1866 years) and 50.8 (2872 years) in the malignant group. We had Ultrasound scans before biopsy, surgery, chemotherapy, or radiotherapy. The length of tumors ranges from 7 mm to 39 mm. Inclusion criteria: patients who did not undergo radiotherapy, chemotherapy, or biopsy before examination; exclusion criteria: those with cystic or cysticsolid lesions as seen on two-dimensional ultrasound. A total of 322 solid lesions underwent surgery with the definite pathological diagnosis. Among them, 60 of the 322 lesions (18.6%) were diagnosed as malignant including 56 nonspecific invasive carcinoma and four ductal carcinomas in pathological diagnosis. Total 262 cases (81.4%) were benign lesions including 162 fibroadenomas, 52 adenopathies with fibroadenomas, 39 adenopathies, two lipomas, one pyogenic inflammation, six intraductal papillomas (Table 1) in the pathological classification. BI-RADS is the most commonly used classification system to assess the malignant and benign lesions. The blood-flow parameter method, BI-RADS classification method, and
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DIAGNOSTIC VALUE OF 3D-PDA COMBINED WITH VOCAL
TABLE 1. The Pathological Types of 322 Lesions Benign (n = 262)
Malignant (n = 60)
Pathology
n
Pathology
n
Fibroadenoma
162
56
Adenopathy with fibroadenoma adenopathy Lipoma Pyogenic inflammation Intraductal papilloma
52
Nonspecific invasive carcinoma Ductal carcinoma
4
39 2 1 6
their combination method are compared in this study to find the most accurate noninvasive examination method which could provide information for diagnosis, treatment options, and prognosis of breast tumors. Therefore, the study of quantitative assessment of blood vessels in benign/malignant breast masses promises to improve cancer screening and to provide a reference for clinical treatment. In the 60 malignant cases, eight were classified as BI-RADS 3, 46 as BI-RADS 4, and six as BI-RADS 5 in imaging diagnosis. Among the 262 benign lesions, there were 202 classified as BI-RADS 3, 60 as BI-RADS 4, zero as BI-RADS 5 in imaging diagnosis. In benign or malignant breast masses, age, gray mean, and power mean follow the normal distribution. The average age and power of the malignant group were greater than those of the benign group, ie p < .01 which exhibited significant differences. The MG of the malignant group was lower than that of the benign group, ie p > .05 which exhibited no significant differences between benign and malignant groups. The ratio, vascular flow index and volume follow a non-normal distribution which had significant differences, ie p < .01 (Table 2) (Figs 1 and 2). The area under the ROC curve (AUC) were 0.864, 0.830, 0.800, 0.758, and 0.764 for age, power, ratio, vascular flow index, and volume, respectively. The research indicators were higher than 50% of the curve showing their diagnostic value (Table 3 and Fig 3). The cut-off points of age, power, ratio, blood flow index, and volume were 37.5, 26.56, 0.031, 0.846, and 1.75, respectively. Their corresponding sensitivity were 93.3%, 75%, 81.7%, 68.3%, 63.3% and the specificity were 68.7%, 81%, 70.2%, 75.6%, and 81.7%, respectively. These indices showed their clinical significance in terms of differentiating the benign or malignant breast masses (p < .001) (Table 3).
Figure 1. 3-dimensional imaging and checking of breast Fibroadenoma. (Color version of figure is available online.)
Figure 2. 3-dimensional imaging and checking of breast of nonspecific invasive carcinoma. (Color version of figure is available online.)
The purple line is higher than other color lines which shows age has bigger AUC and better diagnostic value than mass volume and other vascular indices (Fig 3). Comparison of vascular indices Combining with the BIRADS score and Simple BI-RADS method, the AUC of power + BI-RADS, ratio + BI-RADS, VFI + BI-RADS, and BI-RADS alone are 0.928, 0.903, 0.895, and 0.796, respectively, which were higher than 50% of the curve,
TABLE 2. The Comparison of Age, Vascular Indices and Mass Volume Between Benign and Malignant Breast Masses
Age (x § s) Gray mean (x § s) Power mean (x § s) Ratio (median § quartile) Vascular flow index (VFI) (median § quartile) Volume (median § quartile)
Benign
Malignant
33.80 § 10.42 36.26 § 8.03 21.71 § 5.21 0.02 [0.010.04] 0.44 [0.200.83] 0.5 [0.31.4]
50.83 § 11.08 30.96 § 5.22 30.49 § 7.36 0.62 [0.0350.14] 1.12 [0.572.24] 2.75 [0.64.6]
p-value 0.000 0.07 0.000 0.000 0.000 0.000
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WANG ET AL
TABLE 3. Results of Receiver Operating Characteristic (ROC) Analysis of each vascular index
Age Power Ratio VFI Volume (cm3)
AUC
Cut-off point
Sensitivity (%)
Specificity (%)
p value
0.864 0.830 0.800 0.758 0.764
37.5 26.56 0.031 0.846 1.75
93.3 75 81.7 68.3 63.3
68.7 81 70.2 75.6 81.7
<0.001 <0.001 <0.001 <0.001 <0.001
The green line is higher than other color lines which shows power + BI-RADS has bigger AUC and better diagnostic value than other vascular indices combining with the BI-RADS score and simple BI-RADS method (Fig 4).
DISCUSSION
Figure 3. Graph shows ROC curve for age. Vascular indices and volume. (Color version of figure is available online.)
showing that the evaluation method could be used to differentiate the malignant and benign masses. Sensitivity was 81.7%, 80%, 88.3%, 86.7% and specificity was 88.5%, 85.5%, 77.1%, 69.5%, respectively. ROC showed that the AUC of three blood flow indices combined with BI-RADS method were higher than that of single BI-RADS method (Fig 4). The power + BI-RADS method has the highest AUC among these three methods (Table 4 and Fig. 4).
In this study, the gray scale has low diagnostic value in terms of differentiating between the benign and the malignant breast masses that are consistent with the findings of Wang et al (6) Most of the benign and malignant breast lesions display inner low echo level. The small malignant lesions display the homogeneous echo, whereas the internal echoes of large malignant breast tumors can be inhomogeneous because of interior liquefaction, necrosis, or calcification. It is difficult to distinguish malignant lesions from benign lesions with unclear margins. Therefore, gray scale index was ignored in the judgment of benign or malignant tumors. Ductal carcinoma often leads to a poorer prognosis compared to nonspecific invasive carcinoma (7). The average age and the average volume of solid intraductal carcinoma in this study (four cases) were higher than the critical values, ie 37.5 years and 1.75 cm3, respectively. Lateef et al reported 77% of patients with intraductal cancer were over 40 years old (8). Among four cases, one patient showed two different pathologies in two different masses, intraductal and nonspecific invasive carcinoma. And the lesion from another patient showed combined intraductal carcinoma and nonspecific invasive carcinoma pathology. The two-dimensional sonogram is not able to easily identify intraductal carcinoma and nonspecific invasive carcinoma. The exclusion of cystic solid lesions in the study may be due to the insufficient number of subjects and limited information provided. Sirous et al studied 1110 cases of breast masses with Doppler technique and found that the number of blood vessels in malignant masses were much higher than those TABLE 4. The Comparison of BI-RADS Method and BI-RADS Combing with Vascular Indices
Figure 4. ROC curve of BI-RADS method and BI-RADS combing with vascular indices. (Color version of figure is available online.)
4
Power+BI-RADS Ratio + BI-RADS VFI + BI-RADS BI-RADS
AUC
Sensitivity (%)
Specificity (%)
0.928 0.903 0.895 0.796
81.7 80 88.3 86.7
88.5 85.5 77.1 69.5
ARTICLE IN PRESS Academic Radiology, Vol &, No &&, && 2019
benign ones, but its clinical significance in judging benign and malignant tumors was limited (9). Therefore, we further quantify the distribution of blood vessels in breast masses. In this study, the power, ratio, and vascular flow index of malignant tumors were higher than those of benign tumors (p < .01). Nagy et al's study showed that capillaries and veins in malignant tumors could be distorted and enlarged, and the lesions can be classified into six types according to the structures and functions. The distribution of blood vessels in malignant tumors was very random and complex (10). Three-dimensional power Doppler technique can fully display the overall endmost blood flow in the tumor vascular structure that improves the visualization of the internal blood flow in breast cancer. The sensitivity/specificity of power index, ratio index, and vascular flow index in this study were 75%/81% (highest specificity), 81.7% (highest sensitivity)/70.2%, and 68.3%/75.6%, respectively. The structure of blood vessels in benign tumors has more similarities to that of surrounding glands, whereas the neovascularization, irregular shape, and even arteriovenous fistula in malignant tumors usually have abnormal features which can be detected. Clare and Mitchell (11) considered that blood vessels in breast cancer were not a random distribution. Some risk factors may get neglected and the relevant studies should be continued to investigate possible reasons for tumor occurrence in specific locations. It is possible that the growth direction of tumors may be predicted by measuring local blood flow parameters to provide more reference for clinical practice. Contrast-enhanced ultrasound is currently widely used in the sonographic diagnosis of breast tumors. Leng et al (12) found that the peripheral tissue of malignant masses showed more perfusion characteristics than the central region when using contrastenhanced ultrasound to test the micro-vessel density in breast masses. In this study, the visualization and measurement of the internal/peripheral blood flow in the tumor can also be achieved using the three-dimensional power imaging than the central region when using contrast-enhanced ultrasound to test the micro-vessel density in breast masses. Three-dimensional power imaging in this study can also visualize the distribution of the internal and peripheral blood flow of the tumor. Normalization of tumor vessels alleviates hypoxia in tumor microenvironment (1317), that can reduce the malignancy of tumors and increase the efficacy of traditional therapies (1820). Currently, contrastenhanced ultrasound can measure blood flow parameters and evaluate blood flow morphology using the diffusion software (21,22) . Moreover, detecting the tumor vascularization change in solid tumors is easier than detecting the tumor volume change in nonsolid tumors (2326). Therefore, contrast echocardiography is used as a method to evaluate the vascular response to antiangiogenic therapy and targeted therapy. Compared to the contrast-enhanced ultrasound, VOCAL combined with threedimensional power Doppler method is simpler, less laborious, and more repeatable than contrast echocardiography. The feasibility and stability of this methodology will be further verified and confirmed with a large sample size beyond that in this study.
DIAGNOSTIC VALUE OF 3D-PDA COMBINED WITH VOCAL
CONCLUSION Quantitative measurement of blood flow and blood vessel distribution in breast tumors by 3D-PDA combined with the VOCAL method is an important supplement to twodimensional Ultrasound, which combined with traditional twodimensional Ultrasound has more accurate and more sensitive than the traditional two-dimensional Ultrasound alone. This method has promising applications in many current hot research areas, such as the studies of the random distribution of intratumoral blood vessels and the normalization of tumor blood vessels, etc 3D-PDA combined with the VOCAL method provides a new approach to achieve accurate judgments and evaluate the curative effect of treatments in breast cancer patients.
REFERENCES 1.
2. 3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Rathinavelu A, Alhazzani K, Dhandayuthapani S, et al. Anti-cancer effects of F16: a novel vascular endothelial growth factor receptor-specific inhibitor. Tumour Biol 2017; 39(11). https://doi.org/10.1177/ 1010428317726841. Botelho MC, Alves H. Endothelial progenitor cells in breast cancer. Int J Immunother Cancer Res 2016; 2:1–2. Shia WC, Huang YL, Wu HK, et al. Using flow characteristics in threedimensional power Doppler ultrasound imaging to predict complete responses in patients undergoing neoadjuvant chemotherapy. J Ultrasound Med 2017; 36(5):887–900. https://doi.org/10.7863/ultra.16.02078. Yamasato K, Zalud I. Three dimensional power Doppler of the placenta and its clinical applications. J Perinat Med 2017; 45(6):693–700. https:// doi.org/10.1515/jpm-2016-0366. Kupeli A, Sibel K, Eyuboglu I, et al. Role of 3D power Doppler ultrasound in the further characterization of suspicious breast masses. Eur. J. Radiol. 2016; 85:1–6. http://dx.doi.org/10.1016/j.ejrad.2015.10.019. Wang EF, Fu MG, Gao JX. The value of 3D power Doppler angiography and quantitative parameters in the diagnosis of small breast cancer. Chin J Ultrasound Med 2015; 31(10):901–903. Mathew J, Lee S, Syed BM, et al. A study of ductal versus non-ductal invasive breast carcinomas in older women: long-term clinical outcome and comparison with their younger counterparts. Breast Cancer Res Treat 2014; 147(3):671–674. https://doi.org/10.1007/s10549-014-3094-4. Lateef F, Jama S, Nasir S, et al. Invasive ductal carcinoma: correlation of immunophenotypic features with age. J Coll Phys Surg Pak 2017; 27(1). https://doi.org/2514. Sirous M, Sirous R, Nejad FK, et al. Evaluation of different aspects of power Doppler sonography in differentiating and prognosticationof breast masses. J Res Med Sci 2015; 20(2):133–139. Nagy JA, Chang SH, Shih SC, et al. Heterogeneity of the tumor vasculature. Semin Thromb Hemost 2010; 36(3):321–331. https://doi.org/ 10.1055/s-0030-1253454. Yu C, Mitchell JK. Non-randomness of the anatomical distribution of tumors. Cancer Convergence 2017; 1(1):4. https://doi.org/10.1186/ s41236-017-0006-7. Leng X, Huang G, Ma F, et al. Regional Contrast-Enhanced Ultrasonography (CEUS) characteristics of breast cancer and correlation with Microvessel Density (MVD). Med Sci Monit 2017; 23. https://doi.org/ 10.12659/msm.901734. Li W, Quan YY, Li Y, et al. Monitoring of tumor vascular normalization: the key points from basic research to clinical application. Cancer Manag Res 2018; 10:4163–4172. https://doi.org/10.2147/CMAR.S174712. Huang Y, Goel S, Duda DG, et al. Vascular normalization as an emerging strategy to enhance cancer immunotherapy. Cancer Res 2013; 73 (10):2943–2948. https://doi.org/10.1158/0008-5472.CAN-12-4354. Viallard C, Larrivee B. Tumor angiogenesis and vascular normalization: alternative therapeutic targets. Angiogenesis 2017; 20(4):409–426. https://doi.org/10.1007/s10456-017-9562-9. Martin JD, Fukumura D, Duda DG, et al. Reengineering the tumor microenvironment to alleviate hypoxia and overcome cancer heterogeneity. Cold Spring Harb Perspect Med 2016; 6(12). https://doi.org/10.1101/ cshperspect.a027094.
5
ARTICLE IN PRESS WANG ET AL
17.
18.
19.
20.
21.
6
Ning T, Jiang M, Peng Q, et al. Low-dose endostatin normalizes the structure and function of tumor vasculature and improves the delivery and anti-tumor efficacy of cytotoxic drugs in a lung cancer xenograft murine model. Thorac Cancer 2012; 3(3):229–238. https://doi.org/ 10.1111/j.1759-7714.2012.00111.x. Huber PE, Bischof M, Jenne Jr, et al. Trimodal cancer treatment: beneficial effects of combined antiangiogenesis, radiation, and chemotherapy. Cancer Res 2005; 65(9):3643–3655. Lin MI, Sessa WC. Antiangiogenic therapy: creating a unique “window” of opportunity. Cancer Cell 2004; 6(6):529–531. https://doi.org/10.1016/ j.ccr.2004.12.003. Huang Y, Yuan J, Righi E, et al. Vascular normalizing doses of antiangiogenic treatment reprogram the immunosuppressive tumor microenvironment and enhance immunotherapy. Proc Natl Acad Sci U S A 2012; 109 (43):17561–17566. https://doi.org/10.1073/pnas.1215397109. Hoyt K, Umphrey H, Lockhart M, et al. Ultrasound imaging of breast tumor perfusion and neovascular morphology. Ultrasound Med Biol 2015; 41 (9):2292–2302. https://doi.org/10.1016/j.ultrasmedbio.2015.04.016.
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22. Hudson JM, Ross Williams B, Karshafian R. Quantifying vascular heterogeneity using microbubble disruption-replenishment kinetics in patients with renal cell cancer. Invest Radiol 2014; 49:116–123. 23. Lassau N, Bonastre J, Kind Ml. Validation of dynamic contrast-enhanced ultrasound in predicting outcomes of antiangiogenic therapy for solid tumors. Invest Radiol 2014; 49:794–800. 24. Lassau N, Chapotot L, Benatsou B. Standardization of dynamic contrast-enhanced ultrasound for the evaluation of antiangiogenic therapies. Invest Radiol 2012; 47:711–716. 25. Frampas E, Lassau N, Zappa M, et al. Advanced hepatocellular carcinoma: early evaluation of response to targeted therapy and prognostic value of perfusion CT and dynamic contrast enhanced-ultrasound. Preliminary results. Eur J Radiol 2013; 82(5):e205–e211. https://doi.org/ 10.1016/j.ejrad.2012.12.004. 26. Lassau N, Coiffier B, Faivre L, et al. Study of intrapatient variability and reproducibility of quantitative tumor perfusion parameters evaluated with dynamic contrast-enhanced ultrasonography. Invest Radiol 2017; 52 (3):148–154. https://doi.org/10.1097/RLI.0000000000000324.
Original Investigation
The diagnostic value of 3D power Doppler ultrasound combined with VOCAL in the vascular distribution of breast masses Huizhu Wang, MDy, Bing Yan, PhDy, Lifang Yue, MD, Mingyu He, PhD, Yuehua Liu, MD, Hezhou Li, MD Abbreviations MG Gray Mean MP Power Mean VFI vascular flow index AUC Under the area of the ROC curve 3D-PDA three-dimensional power Doppler Ultrasound VOCAL Virtual Organ-aided Analysis BI-RADS Breast imaging reporting and data System
Rationale and Objectives: This study uses a three-dimensional energy Doppler technique combined with the Virtual Organ Computer-aided Analysis (VOCAL) method in order to determine the diagnostic threshold of blood flow index in breast tumors to provide a reference for evaluation and treatment options. Materials and methods: We collected 322 solid lesions which had been operated. Each lesion met the definite pathological diagnosis; collected lesions included 262 cases of benign lesions and 60 cases of malignant lesions. All examinations were performed by using GE LOGIQ E9 with VOCAL software. Volume and four distinct vascular indices of gray mean (MG), power mean, ratio (R), and vascular flow index (VFI) were calculated by using the VOCAL software. Sampling and calculation were repeated three times and the mean value was calculated. Results: The average age and power of the malignant group were greater than those of the benign group, ie p < .01 which had significant differences. The gray mean of the malignant group was lower than that of the benign group, ie p > .05 which had no significant differences between benign and malignant groups. The ratio, vascular flow index and volume had significant differences, i.e. p < .01. The area under the receiver operating characteristic curve (AUC) were 0.864, 0.830, 0.800, 0.758, and 0.764 for age, power, ratio, vascular flow index, and volume, respectively. The research indicators were higher than 50% of the curve showing their diagnostic value. The cut-off points of age, power, ratio, vascular flow index, and volume were 37.5, 26.56, 0.031, 0.846, and 1.75, respectively. Their corresponding sensitivity were 93.3%, 75%, 81.7%, 68.3%, 63.3%, and the specificity were 68.7%, 81%, 70.2%, 75.6%, and 81.7%, respectively. Comparison of vascular indices combined with the Breast imaging reporting and data System (BI-RADS) score and simple BI-RADS method, the AUC of power + BI-RADS, ratio + BI-RADS, VFI + BI-RADS, and BI-RADS alone are 0.928, 0.903, 0.895, and 0.796, respectively, which were higher than 50% of the curve. Sensitivity was 81.7%, 80%, 88.3%, 86.7%, and specificity was 88.5%, 85.5%, 77.1%, 69.5%, respectively. The power + BI-RADS method has the highest AUC among these three methods. Conclusions: Quantitative measurement of blood flow and blood vessel distribution in breast tumors by three-dimensional power Doppler ultrasound combined with the VOCAL method is more accurate and sensitive than the traditional two-dimensional ultrasound. And this method has potential promising applications in many current active research areas, such as the studies of random distribution of intratumoral blood vessels or the normalization of tumor blood vessels. Three-dimensional power Doppler ultrasound combined with the VOCAL method provides a new approach to achieving accurate judgments and the method evaluates the curative effect in breast cancer patients. Key Words: VOCAL; 3-dimensional; Power Doppler; Ultrasound; Breast; BI-RADS. © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Acad Radiol 2019; &:1–6 From the Department of Ultrasound, the third affiliated hospital of Zhengzhou University, No. 7 Kangfu Qian Street, Erqi District, Zhengzhou, 450052, China (H.W., L.Y., H.L.); Henan Key Laboratory of Digestive Organ Transplantation, the first affiliated hospital of Zhengzhou University, Zhengzhou, China (B.Y.); Center for ultrasound molecular imaging and therapeutics, School of medicine, University of Pittsburgh, Pittsburgh, PA, USA (M.H.); Department of Obstetrics and Gynecology, the third affiliated hospital of Zhengzhou University, Zhengzhou, China (Y.L.). Received January 19, 2019; revised February 27, 2019; accepted February 28, 2019. Declare of interests: No author declared competing interests. The authors declare that all data supporting the findings of this study are available within the article and its additional files. The corresponding author had full access to all data and final responsibility for the decision to submit the manuscript for publication. Address correspondence to: H.L. e-mail: [email protected] y These authors contributed equally to this work. © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.acra.2019.02.023
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ARTICLE IN PRESS WANG ET AL
INTRODUCTION
T
he incidence of breast cancer is increasing yearly, early diagnosis and treatment deliver the best prognosis. It’s reported that breast cancer cells produce vascular endothelial growth factor, which can stimulate the growth of blood vessels accompanied by the morphological changes (1,2). The malignant vessel differs from normal ones, which include uneven thickness, increased density, and irregular serpentine courses. Using the vascular 3D ultrasound imaging technology, the dilated afferent artery, and the abundant heterogeneous interior vasculature with regard to organization and structure malformation, and even arteriovenogenesis, are usually observed in malignant tumors by visualizing the internal vasculature. Whereas, the peripheral structures of blood vessels near the benign counterpart usually show regular and normal vessel morphology. Three-dimensional power Doppler Ultrasound (3D-PDA) is a newly developed technology combing the three-dimensional ultrasound with power Doppler. 3D-PDA provides clear and comprehensive sonogram images, tumor-related blood flow information, low-velocity blood flow change data, tracks the construction and distribution of blood vessels in tumors, as well as improves diagnostic accuracy of breast malignant tumors (3,4). Virtual Organ Computer-aided Analysis (VOCAL) software is the computer-guided virtual histology analysis, which can calculate the gray mean (MG) (average gray in interesting area), power mean (average brightness value of color voxels), ratio (proportion of color voxels in interesting area), and vascular flow index ([VFI], power mean multiples by ratio) to quantify the distribution of blood vessels in breast tumors. VOCAL was originated from 3D-view and 4D-view software installed on Krez machine which was acquired by GE company and was also developed and installed on the GE LOGIQ from 2007. At present, the studies of vascular distribution in breast masses working to differentiate malignant tumors from benign tumors are hot topics attracting interest from researchers and clinicians, while most studies are qualitative evaluation and lack quantitative evaluation. In this study, three-dimensional power Doppler technique combining with VOCAL method (5) was used to determine the diagnostic threshold of blood flow index in breast tumors and provide a reference for evaluation and treatment options. MATERIALS AND METHODS All examinations were performed by using GE LOGIQ E9 with a volumetric linear probe. This transducer is a broadbased linear-array probe with a frequency of 612 MHz, it has 50 mm scanning width and a sweep angle of 529° to allow for the performance of a 3D volume scan. Patients took off their upper outer garment, lay in a supine position, and place their arms over the head. During the performed 3D volume scan, all patients were asked to hold their breath approximately 20 seconds. The following power Doppler 2
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settings were used to standardize our assessment of breast vascularization: (frequency 6.3; gain 19.0; pulse repetition frequency, 0.8 KHz; wall motion filter, 100; line density/frame average 3/6; sample volume/package size 4/14; artifact on 100%). After the mass was localized in the 2D view, 3D static power Doppler scanning was performed by using the widest scanning angle (30°) covering the whole breast mass. After the examination, the VOCAL software was used to obtain the volume data. The rotation angle was set to 30°and six different consecutive mass sections were obtained. The volume and three vascular indices of gray mean (MG), power mean (MP), ratio (R) and vascular flow index (VFI) were calculated using the VOCAL software. Sampling and calculation were repeated three times and the mean value was calculated. Each data group was completed by two ultrasound doctors who had 10+ years of ultrasound examination experience. Data Analysis
IBM SPSS software (24.0 version, Armonk, NY) was used for statistical analysis of the data. The data that follow normal distribution are compared by Independent-Sample t Test, and the data that follow non-normal distribution are compared by Nonparametric Tests. Multivariate analysis was performed by logistic regression analysis. Age, mass volume, vascular indices, simple Breast imaging reporting and data System (BI-RADS) score, and BI-RADS method combing with vascular indices were evaluated by the receiver operating characteristic curve (ROC). The ROC was used to determine the diagnostic efficiency. A p < .05 was considered statistically significant.
RESULTS A total of 222 patients (age range, 1872 years; mean age, 37.0 years) were treated in our hospital between May 2016November 2017. The median age of the benign group is 33.8 (1866 years) and 50.8 (2872 years) in the malignant group. We had Ultrasound scans before biopsy, surgery, chemotherapy, or radiotherapy. The length of tumors ranges from 7 mm to 39 mm. Inclusion criteria: patients who did not undergo radiotherapy, chemotherapy, or biopsy before examination; exclusion criteria: those with cystic or cysticsolid lesions as seen on two-dimensional ultrasound. A total of 322 solid lesions underwent surgery with the definite pathological diagnosis. Among them, 60 of the 322 lesions (18.6%) were diagnosed as malignant including 56 nonspecific invasive carcinoma and four ductal carcinomas in pathological diagnosis. Total 262 cases (81.4%) were benign lesions including 162 fibroadenomas, 52 adenopathies with fibroadenomas, 39 adenopathies, two lipomas, one pyogenic inflammation, six intraductal papillomas (Table 1) in the pathological classification. BI-RADS is the most commonly used classification system to assess the malignant and benign lesions. The blood-flow parameter method, BI-RADS classification method, and
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DIAGNOSTIC VALUE OF 3D-PDA COMBINED WITH VOCAL
TABLE 1. The Pathological Types of 322 Lesions Benign (n = 262)
Malignant (n = 60)
Pathology
n
Pathology
n
Fibroadenoma
162
56
Adenopathy with fibroadenoma adenopathy Lipoma Pyogenic inflammation Intraductal papilloma
52
Nonspecific invasive carcinoma Ductal carcinoma
4
39 2 1 6
their combination method are compared in this study to find the most accurate noninvasive examination method which could provide information for diagnosis, treatment options, and prognosis of breast tumors. Therefore, the study of quantitative assessment of blood vessels in benign/malignant breast masses promises to improve cancer screening and to provide a reference for clinical treatment. In the 60 malignant cases, eight were classified as BI-RADS 3, 46 as BI-RADS 4, and six as BI-RADS 5 in imaging diagnosis. Among the 262 benign lesions, there were 202 classified as BI-RADS 3, 60 as BI-RADS 4, zero as BI-RADS 5 in imaging diagnosis. In benign or malignant breast masses, age, gray mean, and power mean follow the normal distribution. The average age and power of the malignant group were greater than those of the benign group, ie p < .01 which exhibited significant differences. The MG of the malignant group was lower than that of the benign group, ie p > .05 which exhibited no significant differences between benign and malignant groups. The ratio, vascular flow index and volume follow a non-normal distribution which had significant differences, ie p < .01 (Table 2) (Figs 1 and 2). The area under the ROC curve (AUC) were 0.864, 0.830, 0.800, 0.758, and 0.764 for age, power, ratio, vascular flow index, and volume, respectively. The research indicators were higher than 50% of the curve showing their diagnostic value (Table 3 and Fig 3). The cut-off points of age, power, ratio, blood flow index, and volume were 37.5, 26.56, 0.031, 0.846, and 1.75, respectively. Their corresponding sensitivity were 93.3%, 75%, 81.7%, 68.3%, 63.3% and the specificity were 68.7%, 81%, 70.2%, 75.6%, and 81.7%, respectively. These indices showed their clinical significance in terms of differentiating the benign or malignant breast masses (p < .001) (Table 3).
Figure 1. 3-dimensional imaging and checking of breast Fibroadenoma. (Color version of figure is available online.)
Figure 2. 3-dimensional imaging and checking of breast of nonspecific invasive carcinoma. (Color version of figure is available online.)
The purple line is higher than other color lines which shows age has bigger AUC and better diagnostic value than mass volume and other vascular indices (Fig 3). Comparison of vascular indices Combining with the BIRADS score and Simple BI-RADS method, the AUC of power + BI-RADS, ratio + BI-RADS, VFI + BI-RADS, and BI-RADS alone are 0.928, 0.903, 0.895, and 0.796, respectively, which were higher than 50% of the curve,
TABLE 2. The Comparison of Age, Vascular Indices and Mass Volume Between Benign and Malignant Breast Masses
Age (x § s) Gray mean (x § s) Power mean (x § s) Ratio (median § quartile) Vascular flow index (VFI) (median § quartile) Volume (median § quartile)
Benign
Malignant
33.80 § 10.42 36.26 § 8.03 21.71 § 5.21 0.02 [0.010.04] 0.44 [0.200.83] 0.5 [0.31.4]
50.83 § 11.08 30.96 § 5.22 30.49 § 7.36 0.62 [0.0350.14] 1.12 [0.572.24] 2.75 [0.64.6]
p-value 0.000 0.07 0.000 0.000 0.000 0.000
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WANG ET AL
TABLE 3. Results of Receiver Operating Characteristic (ROC) Analysis of each vascular index
Age Power Ratio VFI Volume (cm3)
AUC
Cut-off point
Sensitivity (%)
Specificity (%)
p value
0.864 0.830 0.800 0.758 0.764
37.5 26.56 0.031 0.846 1.75
93.3 75 81.7 68.3 63.3
68.7 81 70.2 75.6 81.7
<0.001 <0.001 <0.001 <0.001 <0.001
The green line is higher than other color lines which shows power + BI-RADS has bigger AUC and better diagnostic value than other vascular indices combining with the BI-RADS score and simple BI-RADS method (Fig 4).
DISCUSSION
Figure 3. Graph shows ROC curve for age. Vascular indices and volume. (Color version of figure is available online.)
showing that the evaluation method could be used to differentiate the malignant and benign masses. Sensitivity was 81.7%, 80%, 88.3%, 86.7% and specificity was 88.5%, 85.5%, 77.1%, 69.5%, respectively. ROC showed that the AUC of three blood flow indices combined with BI-RADS method were higher than that of single BI-RADS method (Fig 4). The power + BI-RADS method has the highest AUC among these three methods (Table 4 and Fig. 4).
In this study, the gray scale has low diagnostic value in terms of differentiating between the benign and the malignant breast masses that are consistent with the findings of Wang et al (6) Most of the benign and malignant breast lesions display inner low echo level. The small malignant lesions display the homogeneous echo, whereas the internal echoes of large malignant breast tumors can be inhomogeneous because of interior liquefaction, necrosis, or calcification. It is difficult to distinguish malignant lesions from benign lesions with unclear margins. Therefore, gray scale index was ignored in the judgment of benign or malignant tumors. Ductal carcinoma often leads to a poorer prognosis compared to nonspecific invasive carcinoma (7). The average age and the average volume of solid intraductal carcinoma in this study (four cases) were higher than the critical values, ie 37.5 years and 1.75 cm3, respectively. Lateef et al reported 77% of patients with intraductal cancer were over 40 years old (8). Among four cases, one patient showed two different pathologies in two different masses, intraductal and nonspecific invasive carcinoma. And the lesion from another patient showed combined intraductal carcinoma and nonspecific invasive carcinoma pathology. The two-dimensional sonogram is not able to easily identify intraductal carcinoma and nonspecific invasive carcinoma. The exclusion of cystic solid lesions in the study may be due to the insufficient number of subjects and limited information provided. Sirous et al studied 1110 cases of breast masses with Doppler technique and found that the number of blood vessels in malignant masses were much higher than those TABLE 4. The Comparison of BI-RADS Method and BI-RADS Combing with Vascular Indices
Figure 4. ROC curve of BI-RADS method and BI-RADS combing with vascular indices. (Color version of figure is available online.)
4
Power+BI-RADS Ratio + BI-RADS VFI + BI-RADS BI-RADS
AUC
Sensitivity (%)
Specificity (%)
0.928 0.903 0.895 0.796
81.7 80 88.3 86.7
88.5 85.5 77.1 69.5
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benign ones, but its clinical significance in judging benign and malignant tumors was limited (9). Therefore, we further quantify the distribution of blood vessels in breast masses. In this study, the power, ratio, and vascular flow index of malignant tumors were higher than those of benign tumors (p < .01). Nagy et al's study showed that capillaries and veins in malignant tumors could be distorted and enlarged, and the lesions can be classified into six types according to the structures and functions. The distribution of blood vessels in malignant tumors was very random and complex (10). Three-dimensional power Doppler technique can fully display the overall endmost blood flow in the tumor vascular structure that improves the visualization of the internal blood flow in breast cancer. The sensitivity/specificity of power index, ratio index, and vascular flow index in this study were 75%/81% (highest specificity), 81.7% (highest sensitivity)/70.2%, and 68.3%/75.6%, respectively. The structure of blood vessels in benign tumors has more similarities to that of surrounding glands, whereas the neovascularization, irregular shape, and even arteriovenous fistula in malignant tumors usually have abnormal features which can be detected. Clare and Mitchell (11) considered that blood vessels in breast cancer were not a random distribution. Some risk factors may get neglected and the relevant studies should be continued to investigate possible reasons for tumor occurrence in specific locations. It is possible that the growth direction of tumors may be predicted by measuring local blood flow parameters to provide more reference for clinical practice. Contrast-enhanced ultrasound is currently widely used in the sonographic diagnosis of breast tumors. Leng et al (12) found that the peripheral tissue of malignant masses showed more perfusion characteristics than the central region when using contrastenhanced ultrasound to test the micro-vessel density in breast masses. In this study, the visualization and measurement of the internal/peripheral blood flow in the tumor can also be achieved using the three-dimensional power imaging than the central region when using contrast-enhanced ultrasound to test the micro-vessel density in breast masses. Three-dimensional power imaging in this study can also visualize the distribution of the internal and peripheral blood flow of the tumor. Normalization of tumor vessels alleviates hypoxia in tumor microenvironment (1317), that can reduce the malignancy of tumors and increase the efficacy of traditional therapies (1820). Currently, contrastenhanced ultrasound can measure blood flow parameters and evaluate blood flow morphology using the diffusion software (21,22) . Moreover, detecting the tumor vascularization change in solid tumors is easier than detecting the tumor volume change in nonsolid tumors (2326). Therefore, contrast echocardiography is used as a method to evaluate the vascular response to antiangiogenic therapy and targeted therapy. Compared to the contrast-enhanced ultrasound, VOCAL combined with threedimensional power Doppler method is simpler, less laborious, and more repeatable than contrast echocardiography. The feasibility and stability of this methodology will be further verified and confirmed with a large sample size beyond that in this study.
DIAGNOSTIC VALUE OF 3D-PDA COMBINED WITH VOCAL
CONCLUSION Quantitative measurement of blood flow and blood vessel distribution in breast tumors by 3D-PDA combined with the VOCAL method is an important supplement to twodimensional Ultrasound, which combined with traditional twodimensional Ultrasound has more accurate and more sensitive than the traditional two-dimensional Ultrasound alone. This method has promising applications in many current hot research areas, such as the studies of the random distribution of intratumoral blood vessels and the normalization of tumor blood vessels, etc 3D-PDA combined with the VOCAL method provides a new approach to achieve accurate judgments and evaluate the curative effect of treatments in breast cancer patients.
REFERENCES 1.
2. 3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Rathinavelu A, Alhazzani K, Dhandayuthapani S, et al. Anti-cancer effects of F16: a novel vascular endothelial growth factor receptor-specific inhibitor. Tumour Biol 2017; 39(11). https://doi.org/10.1177/ 1010428317726841. Botelho MC, Alves H. Endothelial progenitor cells in breast cancer. Int J Immunother Cancer Res 2016; 2:1–2. Shia WC, Huang YL, Wu HK, et al. Using flow characteristics in threedimensional power Doppler ultrasound imaging to predict complete responses in patients undergoing neoadjuvant chemotherapy. J Ultrasound Med 2017; 36(5):887–900. https://doi.org/10.7863/ultra.16.02078. Yamasato K, Zalud I. Three dimensional power Doppler of the placenta and its clinical applications. J Perinat Med 2017; 45(6):693–700. https:// doi.org/10.1515/jpm-2016-0366. Kupeli A, Sibel K, Eyuboglu I, et al. Role of 3D power Doppler ultrasound in the further characterization of suspicious breast masses. Eur. J. Radiol. 2016; 85:1–6. http://dx.doi.org/10.1016/j.ejrad.2015.10.019. Wang EF, Fu MG, Gao JX. The value of 3D power Doppler angiography and quantitative parameters in the diagnosis of small breast cancer. Chin J Ultrasound Med 2015; 31(10):901–903. Mathew J, Lee S, Syed BM, et al. A study of ductal versus non-ductal invasive breast carcinomas in older women: long-term clinical outcome and comparison with their younger counterparts. Breast Cancer Res Treat 2014; 147(3):671–674. https://doi.org/10.1007/s10549-014-3094-4. Lateef F, Jama S, Nasir S, et al. Invasive ductal carcinoma: correlation of immunophenotypic features with age. J Coll Phys Surg Pak 2017; 27(1). https://doi.org/2514. Sirous M, Sirous R, Nejad FK, et al. Evaluation of different aspects of power Doppler sonography in differentiating and prognosticationof breast masses. J Res Med Sci 2015; 20(2):133–139. Nagy JA, Chang SH, Shih SC, et al. Heterogeneity of the tumor vasculature. Semin Thromb Hemost 2010; 36(3):321–331. https://doi.org/ 10.1055/s-0030-1253454. Yu C, Mitchell JK. Non-randomness of the anatomical distribution of tumors. Cancer Convergence 2017; 1(1):4. https://doi.org/10.1186/ s41236-017-0006-7. Leng X, Huang G, Ma F, et al. Regional Contrast-Enhanced Ultrasonography (CEUS) characteristics of breast cancer and correlation with Microvessel Density (MVD). Med Sci Monit 2017; 23. https://doi.org/ 10.12659/msm.901734. Li W, Quan YY, Li Y, et al. Monitoring of tumor vascular normalization: the key points from basic research to clinical application. Cancer Manag Res 2018; 10:4163–4172. https://doi.org/10.2147/CMAR.S174712. Huang Y, Goel S, Duda DG, et al. Vascular normalization as an emerging strategy to enhance cancer immunotherapy. Cancer Res 2013; 73 (10):2943–2948. https://doi.org/10.1158/0008-5472.CAN-12-4354. Viallard C, Larrivee B. Tumor angiogenesis and vascular normalization: alternative therapeutic targets. Angiogenesis 2017; 20(4):409–426. https://doi.org/10.1007/s10456-017-9562-9. Martin JD, Fukumura D, Duda DG, et al. Reengineering the tumor microenvironment to alleviate hypoxia and overcome cancer heterogeneity. Cold Spring Harb Perspect Med 2016; 6(12). https://doi.org/10.1101/ cshperspect.a027094.
5
ARTICLE IN PRESS WANG ET AL
17.
18.
19.
20.
21.
6
Ning T, Jiang M, Peng Q, et al. Low-dose endostatin normalizes the structure and function of tumor vasculature and improves the delivery and anti-tumor efficacy of cytotoxic drugs in a lung cancer xenograft murine model. Thorac Cancer 2012; 3(3):229–238. https://doi.org/ 10.1111/j.1759-7714.2012.00111.x. Huber PE, Bischof M, Jenne Jr, et al. Trimodal cancer treatment: beneficial effects of combined antiangiogenesis, radiation, and chemotherapy. Cancer Res 2005; 65(9):3643–3655. Lin MI, Sessa WC. Antiangiogenic therapy: creating a unique “window” of opportunity. Cancer Cell 2004; 6(6):529–531. https://doi.org/10.1016/ j.ccr.2004.12.003. Huang Y, Yuan J, Righi E, et al. Vascular normalizing doses of antiangiogenic treatment reprogram the immunosuppressive tumor microenvironment and enhance immunotherapy. Proc Natl Acad Sci U S A 2012; 109 (43):17561–17566. https://doi.org/10.1073/pnas.1215397109. Hoyt K, Umphrey H, Lockhart M, et al. Ultrasound imaging of breast tumor perfusion and neovascular morphology. Ultrasound Med Biol 2015; 41 (9):2292–2302. https://doi.org/10.1016/j.ultrasmedbio.2015.04.016.
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22. Hudson JM, Ross Williams B, Karshafian R. Quantifying vascular heterogeneity using microbubble disruption-replenishment kinetics in patients with renal cell cancer. Invest Radiol 2014; 49:116–123. 23. Lassau N, Bonastre J, Kind Ml. Validation of dynamic contrast-enhanced ultrasound in predicting outcomes of antiangiogenic therapy for solid tumors. Invest Radiol 2014; 49:794–800. 24. Lassau N, Chapotot L, Benatsou B. Standardization of dynamic contrast-enhanced ultrasound for the evaluation of antiangiogenic therapies. Invest Radiol 2012; 47:711–716. 25. Frampas E, Lassau N, Zappa M, et al. Advanced hepatocellular carcinoma: early evaluation of response to targeted therapy and prognostic value of perfusion CT and dynamic contrast enhanced-ultrasound. Preliminary results. Eur J Radiol 2013; 82(5):e205–e211. https://doi.org/ 10.1016/j.ejrad.2012.12.004. 26. Lassau N, Coiffier B, Faivre L, et al. Study of intrapatient variability and reproducibility of quantitative tumor perfusion parameters evaluated with dynamic contrast-enhanced ultrasonography. Invest Radiol 2017; 52 (3):148–154. https://doi.org/10.1097/RLI.0000000000000324.