Comparing contrast-enhanced color flow imaging and pathological measures of breast lesion vascularity

Diagnostic performance of ACR-TIRADS combined with superb microvascular imaging for differential diagnosis of mummified thyroid nodules and papillary thyroid carcinomas

Objective

The aim was to investigate the ability of superb microvascular imaging (SMI) to improve the differential diagnosis of mummified thyroid nodules (MTNs) and papillary thyroid carcinomas (PTCs) using the 2017 American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS).

Materials and methods

We enrolled 110 cases of MTNs and 110 cases of PTCs confirmed by fine needle aspiration (FNA) or surgery. Conventional ultrasound (US) and the quantity of microvessels detected by SMI were analyzed for all nodules. Thyroid nodules were initially categorized by ACR-TIRADS based on US imaging features and then reclassified based on ACR-TIRADS combined with SMI blood-flow grade (SMI-TIRADS). We compared the diagnostic performances of ACR-TIRADS and SMI-TIRADS by receiver operating characteristic curve, sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV).

Results

US-detected margin, shape, and echogenic foci differed between MTNs and PTCs (P < 0.05). The SMI blood-flow grade was significantly greater in PTCs compared with MTNs (Χ2 = 158.78, P < 0.05). There was no significant difference in ACR-TIRADS indicators between MTNs and PTCs (Χ2 = 1.585, P = 0.453); however, reclassification by SMI-TIRADS showed significant differences between the groups (Χ2 = 129.521, P < 0.001). The area under the curve was significantly lower for ACR-TIRADS compared with SMI-TIRADS (0.517 vs 0.887, P < 0.05). SMI-TIRADS had significantly higher diagnostic value for distinguishing MTNs and PTCs than ACR-TIRADS (sensitivity: 91.82% vs 74.55%, P < 0.05; specificity: 84.55% vs 21.82%, P < 0.05; accuracy: 88.18% vs 48.18%, P < 0.05; PPV: 85.59% vs 48.81%, P < 0.05; and NPV: 91.18% vs 46.15%, P < 0.05).

Conclusion

The detection of microvascular flow and large vessels in thyroid nodules by SMI resulted in high diagnostic specificity and sensitivity. ACR-TIRADS combined with SMI could effectively distinguish between MTNs and PTCs, to avoid unnecessary FNA or surgical excision.

CNN-based automatic segmentations and radiomics feature reliability on contrast-enhanced ultrasound images for renal tumors

Objective

To investigate the feasibility and efficiency of automatic segmentation of contrast-enhanced ultrasound (CEUS) images in renal tumors by convolutional neural network (CNN) based models and their further application in radiomic analysis.

Materials and methods

From 94 pathologically confirmed renal tumor cases, 3355 CEUS images were extracted and randomly divided into training set (3020 images) and test set (335 images). According to the histological subtypes of renal cell carcinoma, the test set was further split into clear cell renal cell carcinoma (ccRCC) set (225 images), renal angiomyolipoma (AML) set (77 images) and set of other subtypes (33 images). Manual segmentation was the gold standard and serves as ground truth. Seven CNN-based models including DeepLabV3+, UNet, UNet++, UNet3+, SegNet, MultilResUNet and Attention UNet were used for automatic segmentation. Python 3.7.0 and Pyradiomics package 3.0.1 were used for radiomic feature extraction. Performance of all approaches was evaluated by the metrics of mean intersection over union (mIOU), dice similarity coefficient (DSC), precision, and recall. Reliability and reproducibility of radiomics features were evaluated by the Pearson coefficient and the intraclass correlation coefficient (ICC).

Results

All seven CNN-based models achieved good performance with the mIOU, DSC, precision and recall ranging between 81.97%-93.04%, 78.67%-92.70%, 93.92%-97.56%, and 85.29%-95.17%, respectively. The average Pearson coefficients ranged from 0.81 to 0.95, and the average ICCs ranged from 0.77 to 0.92. The UNet++ model showed the best performance with the mIOU, DSC, precision and recall of 93.04%, 92.70%, 97.43% and 95.17%, respectively. For ccRCC, AML and other subtypes, the reliability and reproducibility of radiomic analysis derived from automatically segmented CEUS images were excellent, with the average Pearson coefficients of 0.95, 0.96 and 0.96, and the average ICCs for different subtypes were 0.91, 0.93 and 0.94, respectively.

Conclusion

This retrospective single-center study showed that the CNN-based models had good performance on automatic segmentation of CEUS images for renal tumors, especially the UNet++ model. The radiomics features extracted from automatically segmented CEUS images were feasible and reliable, and further validation by multi-center research is necessary.

Role and added value of contrast enhanced ultrasound of the painful scrotum in the emergency setting

Emergency imaging of the scrotum is part of routine medical practice. Indications include epididymitis/epididymo-orchitis, testicular torsion, trauma, tumors and infarction. Prompt diagnosis and management are needed to ensure optimal patient outcome. Ultrasound (US) is the initial, and often the only, imaging modality for testicular pathologies. Usually, B-mode and color Doppler US are adequate. In challenging cases, contrast-enhanced US (CEUS) facilitates final diagnosis or increases the examiner's confidence by confirming findings on non-enhanced US. This paper elaborates on the examination technique of CEUS for testicular pathologies, thereby showing its added value over baseline US techniques in the emergency setting.

A Novel Nomogram Based on Imaging Biomarkers of Shear Wave Elastography, Angio Planewave Ultrasensitive Imaging, and Conventional Ultrasound for Preoperative Prediction of Malignancy in Patients with Breast Lesions

Several studies have demonstrated the difficulties in distinguishing malignant lesions of the breast from benign lesions owing to overlapping morphological features on ultrasound. Consequently, we aimed to develop a nomogram based on shear wave elastography (SWE), Angio Planewave Ultrasensitive imaging (Angio PLUS (AP)), and conventional ultrasound imaging biomarkers to predict malignancy in patients with breast lesions. This prospective study included 117 female patients with suspicious lesions of the breast. Features of lesions were extracted from SWE, AP, and conventional ultrasound images. The least absolute shrinkage and selection operator (Lasso) algorithms were used to select breast cancer-related imaging biomarkers, and a nomogram was developed based on six of the 16 imaging biomarkers. This model exhibited good discrimination (area under the receiver operating characteristic curve (AUC): 0.969; 95% confidence interval (CI): 0.928, 0.989) between malignant and benign breast lesions. Moreover, the nomogram also showed demonstrated good calibration and clinical usefulness. In conclusion, our nomogram can be a potentially useful tool for individually-tailored diagnosis of breast tumors in clinical practice.

Quantitative analysis of superb microvascular imaging for monitoring tumor response to chemoradiotherapy in locally advanced cervical cancer

Objectives

As an ultrasound (US) image processing method, superb microvascular imaging (SMI) extracts and visualizes flow signals from vessels through advanced clutter suppression technology. We investigated the feasibility of SMI in monitoring treatment response in patients with locally advanced cervical cancer (LACC) undergoing chemoradiotherapy (CRT).

Methods

Forty-nine patients underwent CRT and received SMI examination at 3 time points: before therapy (baseline), 3 weeks during, and 1 month after CRT. The maximum tumor diameter (Dmax), vascularity index (VI), and their percentage changes (ΔDmax and ΔVI) were calculated. ΔDmax was compared with MRI results as the reference standard.

Results

Based on the MRI findings, 44 were classified as complete response (CR) group and 5 as partial response (PR) group. The Dmax and ΔDmax showed decrease in CR and PR groups at 3 weeks during CRT (P< 0.05), but no significant difference between the two groups (P > 0.05). Compared to the baseline, significant decrease in VI and ΔVI were observed at during and after treatment in the two groups (P< 0.05). Moreover, there were significant differences in VI and ΔVI at 3 weeks during CRT between the CR and PR groups (P< 0.05). ΔVI at 3 weeks during CRT showed a better predictive performance for responder prognosis than VI (AUC = 0.964, AUC = 0.950, respectively, P = 0.001), with a cut-off value of 41.6% yielding 100% sensitivity and 86.4% specificity.

Conclusions

The SMI parameters (VI and ΔVI) have potential for monitoring treatment response in LACC.

Diagnostic Value of Superb Microvascular Imaging in Differentiating Benign and Malignant Breast Tumors: A Systematic Review and Meta-Analysis

PURPOSE

We performed a systematic review and meta-analysis of studies that investigated the diagnostic performance of Superb Microvascular Imaging (SMI) in differentiating between benign and malignant breast tumors.

METHODS

Studies published between January 2010 and March 2022 were retrieved by online literature search conducted in PubMed, Embase, Cochrane Library, Web of Science, China Biology Medicine Disc, China National Knowledge Infrastructure, Wanfang, and Vip databases. Pooled sensitivity, specificity, and diagnostic odd ratios were calculated using Stata software 15.0. Heterogeneity among the included studies was assessed using I2 statistic and Q test. Meta-regression and subgroup analyses were conducted to investigate potential sources of heterogeneity. Influence analysis was conducted to determine the robustness of the pooled conclusions. Deeks' funnel plot asymmetry test was performed to assess publication bias. A summary receiver operating characteristic curve (SROC) was constructed.

RESULTS

Twenty-three studies involving 2749 breast lesions were included in our meta-analysis. The pooled sensitivity and specificity were 0.80 (95% confidence interval [CI], 0.77-0.84, inconsistency index [I2] = 28.32%) and 0.84 (95% CI, 0.79-0.88, I2 = 89.36%), respectively. The pooled diagnostic odds ratio was 19.95 (95% CI, 14.84-26.82). The area under the SROC (AUC) was 0.85 (95% CI, 0.81-0.87).

CONCLUSION

SMI has a relatively high sensitivity, specificity, and accuracy for differentiating between benign and malignant breast lesions. It represents a promising supplementary technique for the diagnosis of breast neoplasms.

3D Harmonic and Subharmonic Imaging for Characterizing Breast Lesions: A Multi-Center Clinical Trial

OBJECTIVE

Breast cancer is the most frequent type of cancer among women. This multi-center study assessed the ability of 3D contrast-enhanced ultrasound to characterize suspicious breast lesions using clinical assessments and quantitative parameters.

METHODS

Women with suspicious breast lesions scheduled for biopsy were enrolled in this prospective, study. Following 2D grayscale ultrasound and power Doppler imaging (PDI), a contrast agent (Definity; Lantheus) was administrated. Contrast-enhanced 3D harmonic imaging (HI; transmitting/receiving at 5.0/10.0 MHz), as well as 3D subharmonic imaging (SHI; transmitting/receiving at 5.8/2.9 MHz), were performed using a modified Logiq 9 scanner (GE Healthcare). Five radiologists independently scored the imaging modes (including standard-of-care imaging) using a 7-point BIRADS scale as well as lesion vascularity and diagnostic confidence. Parametric volumes were constructed from time-intensity curves for vascular heterogeneity, perfusion, and area under the curve. Diagnostic accuracy was determined relative to pathology using receiver operating characteristic (ROC) and reverse, step-wise logistical regression analyses. The κ-statistic was calculated for inter-reader agreement.

RESULTS

Data were successfully acquired in 219 cases and biopsies indicated 164 (75%) benign and 55 (25%) malignant lesions. SHI depicted more anastomoses and vascularity than HI (P < .021), but there were no differences by pathology (P > .27). Ultrasound achieved accuracies of 82 to 85%, which was significantly better than standard-of-care imaging (72%; P < .03). SHI increased diagnostic confidence by 3 to 6% (P < .05), but inter-reader agreements were medium to low (κ < 0.52). The best regression model achieved 97% accuracy by combining clinical reads and parametric SHI.

CONCLUSIONS

Combining quantitative 3D SHI parameters and clinical assessments improves the characterization of suspicious breast lesions.

The Role of Superb Microvascular Imaging and Shearwave Elastography in the Evaluation of Intraductal Papilloma-Like Lesions

OBJECTIVES

The aim of this study was to investigate the role of quantitative values obtained by superb microvascular imaging (SMI) and shearwave elastography (SWE) in the prediction of malignancy in intraductal papilloma-like lesions (IDPL).

METHODS

In the study, 61 patients between the ages of 14 to 73 years (mean age 44) diagnosed with IDPL on ultrasound (US) examination between the years 2020 and 2021 were included. The B-Mode US findings (shape, margins, size, echo pattern, and accompanying ductal dilatation), SMI vascular index (SMIvi), E-mean, and SWE-ratio values were recorded.

RESULTS

There was a statistically significant difference between malignant (n = 14) and benign (n = 47) groups in terms of symptoms (P = .005), size (P = .042), shape (P = .002), margins (P =  .001), echogenicity (P = .023), microcalcifications (P = .009), SMIvi (P = .031), E-mean (P < .005), and SWE-ratio (P = .007). According to receiver operating characteristic (ROC) curve analysis, sensitivity, specificity, accuracy, area under the curve (AUC), positive predictive values (PPV), and negative predictive values (NPV) were 57.1%, 87.2%, 80%, 0.722, 57.1%, 87.2% for US; 71.4%, 49%, 55.7%, 0.692, 30.3%, 85.7% for SMIvi; 85.7%, 71%, 74%, 0.864, 46%, 94.3% for E-mean, and 50%, 75.4%, 83%, 0.707, 91.5%, and 50% for SWE-ratio, respectively. Best results were obtained when SMI and SWE values were used together, achieving a sensitivity, specificity, accuracy, AUC, PPD, NPD of 78.6%, 93.6%, 93.4%, 0.872, 91.7%, and 93.9%, respectively.

CONCLUSIONS

The SMI and SWE examinations are successful in the differentiation of benign and malignant intraductal lesions. They complement each other and contribute to B-mode US in managing IDPLs especially when used together. Our study is the first to compare the quantitative data of SWE and SMI in the differentiation of IDPLs.

Superb Microvascular Imaging Technology Can Improve the Diagnostic Efficiency of the BI-RADS System

BACKGROUND

To explore whether superb microvascular imaging (SMI)SMI can improve the diagnostic efficiency by evaluating the vascular index (VI) and vascular architecture (VA) in breast lesions.

METHODS

This is a retrospective study of data collected prospectively for research use. Taking 225 consecutive cases of breast lesions from November 2016 to December 2017 as a training set, the VI values and VA types of benign and malignant lesions were calculated based on the pathological results. Taking 238 consecutive cases of breast lesions from January 2018 to October 2018 as the verification set, the diagnostic sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated to compare the diagnostic efficacy.

RESULTS

The training set included 225 breast lesions and the validation set 238 breast lesions. The VI value in the malignant group (10.3 ± 8.0) was significantly higher than that in the benign group (4.3 ± 5.0)(P<0.001). A VI value of 4.05 was used as the diagnostic threshold for differentiating benign from malignant lesions, with a sensitivity of 80.5%, a specificity of 61.9%, an accuracy of 71.1%, a PPV of 62.9%, a NPV of 76.9%, and an area under the curve of 0.758 (0.696-0.819). There was a significant difference in the types of benign and malignant VA (P < 0.001), and the PPV of the root hair-like and crab claw-like VAs were 93.9% and 100.0%, respectively. The diagnostic sensitivity, specificity, accuracy, PPV, NPV and area under the AUC curve were 58.0%, 98.2%, 97.0%, 70.3% and 0.781, respectively (95%CI: 0.719-0.844). SMI combined with conventional ultrasound improved the diagnostic specificity (70.0% vs. 90.0%), accuracy (87.4% vs. 96.6%), and PPV (82.5% vs. 93.2%) without decreasing the diagnostic sensitivity (99.3%), yielded higher diagnostic performance with the area under the ROC curve was 0.941 (95%CI: 0904-0.979) compared with conventional US alone (P < 0.001).

CONCLUSION

A VI value 4.05 is a cut-off value with good diagnostic efficacy. The residual root-like and crab claw-like VAs are the characteristic VAs of malignant lesions. Conventional ultrasound combined with the VI and VA can improve the diagnostic specificity, accuracy and PPV without reducing the diagnostic sensitivity.

Super-resolution ultrasound localization microscopy based on a high frame-rate clinical ultrasound scanner: an in-human feasibility study

Non-invasive detection of microvascular alterations in deep tissuesin vivoprovides critical information for clinical diagnosis and evaluation of a broad-spectrum of pathologies. Recently, the emergence of super-resolution ultrasound localization microscopy (ULM) offers new possibilities for clinical imaging of microvasculature at capillary level. Currently, the clinical utility of ULM on clinical ultrasound scanners is hindered by the technical limitations, such as long data acquisition time, high microbubble (MB) concentration, and compromised tracking performance associated with low imaging frame-rate. Here we present a robust in-human ULM on a high frame-rate (HFR) clinical ultrasound scanner to achieve super-resolution microvessel imaging using a short acquisition time (<10 s). Ultrasound MB data were acquired from different human tissues, including a healthy liver and a diseased liver with acute-on-chronic liver failure, a kidney, a pancreatic tumor, and a breast mass using an HFR clinical scanner. By leveraging the HFR and advanced processing techniques including sub-pixel motion registration, MB signal separation, and Kalman filter-based tracking, MBs can be robustly localized and tracked for ULM under the circumstances of relatively high MB concentration associated with standard clinical MB administration and limited data acquisition time in humans. Subtle morphological and hemodynamic information in microvasculature were shown based on data acquired with single breath-hold and free-hand scanning. Compared with contrast-enhanced power Doppler generated based on the same MB dataset, ULM showed a 5.7-fold resolution improvement in a vessel based on a linear transducer, and provided a wide-range blood flow speed measurement that is Doppler angle-independent. Microvasculatures with complex hemodynamics can be well-differentiated at super-resolution in both normal and pathological tissues. This preliminary study implemented the ultrafast in-human ULM in various human tissues based on a clinical scanner that supports HFR imaging, indicating the potentials of the technique for various clinical applications. However, rigorous validation of the technique in imaging human microvasculature (especially for those tiny vessel structure), preferably with a gold standard, is still required.

Clinical value and application of contrast-enhanced ultrasound in the differential diagnosis of malignant and benign breast lesions

The aim of the present study was to assess the performance of contrast-enhanced ultrasound in distinguishing between malignant and benign breast lesions and the diagnostic value of its clinical application. A total of 52 cases with malignant breast tumors and 73 cases with benign breast lesions were included in the study. Time-intensity curves (TICs) for contrast-enhanced ultrasound were recorded, and the perfusion parameters were obtained and analyzed. Typical features of malignant breast tumors included irregular shape and vascular morphology, uneven contrast agent distribution, filling defects and contrast agent retention, ‘fast-out’ wash-out mode, unclear boundaries and uneven internal echo. Benign lesions were characterized by ‘slow-out’ or synchronous wash-out mode. Regarding perfusion, the starting time of the perfusion of the Sone-Vue microbubble contrast (always 20-30 sec) and time to peak (TTP) were significantly earlier for the malignant lesions, while the wash-out time was later. A significantly greater peak intensity, rising slope and area under the TIC were observed for the malignant breast lesions. All of the malignant breast lesions exhibited an enlarged focus scope on ultrasound, while no obvious focus scope enhancement was observed for benign breast lesions. Furthermore, the TICs of 88.4% of malignant breast lesions were of the fast-rising and slow-declining type, while the TICs of 75.3 and 17.8% of the benign breast lesions were of the slow-rising and fast-declining, and fast-rising and fast-declining type, respectively. Receiver operating characteristics analysis indicated that the TTP, wash-out time and rising slope might contribute to the differential diagnosis between malignant and benign breast lesions. In conclusion, TIC parameters of contrast-enhanced ultrasound have promising clinical value in differentiating between malignant and benign breast lesions. The TTP, wash-out time and rising slope may contribute to the diagnosis of patients with breast lesions to facilitate timely treatment and prognostication of breast cancer patients.

Characterizing Breast Lesions Using Quantitative Parametric 3D Subharmonic Imaging: A Multicenter Study

RATIONALE AND OBJECTIVES

Breast cancer is the leading type of cancer among women. Visualization and characterization of breast lesions based on vascularity kinetics was evaluated using three-dimensional (3D) contrast-enhanced ultrasound imaging in a clinical study.

MATERIALS AND METHODS

Breast lesions (n = 219) were imaged using power Doppler imaging (PDI), 3D contrast-enhanced harmonic imaging (HI), and 3D contrast-enhanced subharmonic imaging (SHI) with a modified Logiq 9 ultrasound scanner using a 4D10L transducer. Quantitative metrics of vascularity derived from 3D parametric volumes (based on contrast perfusion; PER and area under the curve; AUC) were generated by off-line processing of contrast wash-in and wash-out. Diagnostic accuracy of these quantitative vascular parameters was assessed with biopsy results as the reference standard.

RESULTS

Vascularity was observed with PDI in 93 lesions (69 benign and 24 malignant), 3D HI in 8 lesions (5 benign and 3 malignant), and 3D SHI in 83 lesions (58 benign and 25 malignant). Diagnostic accuracy for vascular heterogeneity, PER, and AUC ranged from 0.52 to 0.75, while the best logistical regression model (vascular heterogeneity ratio, central PER, and central AUC) reached 0.90.

CONCLUSION

3D SHI successfully detects contrast agent flow in breast lesions and characterization of these lesions based on quantitative measures of vascular heterogeneity and 3D parametric volumes is promising.

The Vascular Index of Superb Microvascular Imaging Can Improve the Diagnostic Accuracy for Breast Imaging Reporting and Data System Category 4 Breast Lesions

PURPOSE

To investigate whether the vascular index (VI) of superb microvascular imaging (SMI) could improve the diagnostic efficiency for BI-RADS 4 breast lesions and reduce the number of unnecessary biopsies.

PATIENTS AND METHODS

For this study, we selected 222 consecutive BI-RADS 4 breast lesions detected by ultrasound and confirmed by pathology from January 2016 to October 2018. A VI of 4.0 was set as the cutoff value to degrade BI-RADS classification. We calculated the accuracy, sensitivity and PPV of a BI-RADS diagnosis alone and the combination of BI-RADS and the VI.

RESULTS

Pathologically, of the 222 lesions, 129 were confirmed to be benign, and 93 were found to be malignant. A VI of 4.0 was set as the cutoff value; when the VI≤4.0, those BI-RADS 4 masses were downgraded one level (4C-4B, 4B-4A, 4A-3) to an integral BI-RADS grade, while the others maintained the conventional grade. A total of 54 BI-RADS 4 lesions were degraded to BI-RADS 3, including 53 benign lesions and 1 malignant lesion. The diagnostic accuracy (65.3% vs 41.9%) and PPV (54.8% vs 41.9%) were significantly improved. The sensitivity decreased slightly (98.9% vs 100%) because 1 of the 54 downgraded BI-RADS 4 lesions, which had a pathological type of invasive ductal carcinoma, was incorrectly downgraded.

CONCLUSION

SMI is a noninvasive tool for visualizing the vascular structure with high-resolution microvascular images. As a quantitative index, the VI can be used to appropriately downgrade benign lesions classified as BI-RADS 4, which can improve the diagnostic accuracy and PPV and reduce unnecessary biopsies.

Advanced Ultrasound Imaging for Patients in Oncology: DCE-US

Neovascularization is a key stage in the growth of malignancies beyond 2-3 mm³. This neoangiogenesis is an important target for novel anticancer treatments [1], and many new antiangiogenesis or antivascular treatments aim at destroying or limiting the growth of tumor vessels [2].

Vascular index measured by smart 3-D superb microvascular imaging can help to differentiate malignant and benign breast lesion

Purpose: The purpose of our study was to prospectively evaluate the diagnostic performance of the vascular index (VI, defined as the ratio of Doppler signal pixels to pixels in the total lesion) measured via Smart 3-D superb microvascular imaging (SMI) for breast lesions.

Patients and methods: Two hundred and thirty-two consecutive patients with 236 breast lesions referred for biopsy at Peking Union Medical College Hospital were enrolled in the study from December 2016 to November 2017. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of VI were calculated with histopathologic results as the reference standard.

Results: Of the 236 breast lesions, 121 were malignant and 115 were benign. The mean VI was significantly higher in malignant lesions (9.7±8.2) than that in benign ones (3.4±3.3) (P<0.0001). Sensitivity, specificity, PPV, NPV and accuracy of VI (4.0 as the threshold) were respectively: 76.0%, 66.1%, 70.2%, 72.4% and 71.2% (P<0.05).

Conclusion: Smart three-dimensional (3-D) SMI is a noninvasive tool using two-dimensional (2-D) scanning to generate 3-D vascular architecture with a high-resolution image of micro-vessels. This can be used as a qualitative guide to identify the optimal 2-D SMI plane with the most abundant vasculature to guide VI quantitative measurements of breast lesions. Smart 3-D SMI may potentially serve as a noninvasive tool to accurately characterize benign versus malignant breast lesions.

Angiogenesis Research in Mouse Mammary Cancer Based on Contrast-enhanced Ultrasonography: Exploratory Study

RATIONALE AND OBJECTIVES

The objective of this study was to investigate the contrast-enhanced ultrasound (CEUS) characteristics of tumor angiogenesis in mouse mammary cancer.

MATERIALS AND METHODS

Twenty-four mice were examined with ultrasound and CEUS at 2-12 days after implantation. Four to five mice were assessed daily, and one to three mice were then sacrificed for histology. All of the histologic slides were reviewed and correlated with CEUS findings.

RESULTS

A total of 46 cases of ultrasound examination had been performed in 24 mice. The mice were classified into three groups according to the tumor growth: group 1 (2~6 days after implantation, n = 20 cases), group 2 (7~9 days after implantation, n = 15 cases), and group 3 (10~12 days after implantation, n = 11 cases). In group 1, all tumors presented as a homogeneous hypoechoic mass with no color Doppler signals. However, three CEUS patterns were observed: 14 tumors presented as type I (peripheral ring enhancement with no enhancement within the tumor), 4 tumors presented as type II (peripheral ring enhancement with deep penetration), and 2 tumors presented as type III (homogeneous or heterogeneous enhancement in the entire tumor). In group 2, there was only difference in the echo (heterogeneous or not) and color Doppler signals (with or without) among the tumors in conventional ultrasound, but four CEUS patterns were observed and most presented as type III (53.3%, 8/15). In group 3, most tumors presented as a heterogeneous solid mass (81.8%, 9/11) with color signals (100%, 11/11), and almost all tumors presented as enhancement of type IV (peripheral ring enhancement with focal nodular enhancement) (90.9%, 10/11).The histologic results showed that the enhanced areas mainly corresponded to tumor cells, large tortuous vessels, and an inflammatory cell infiltrate. Nonenhanced areas corresponded to large areas of necrotic tissue or tumor cells, which arranged loosely with the small zone of necrosis.

CONCLUSIONS

CEUS could image the progression of vessel formation. Moreover, most importantly, CEUS is able to identify angiogenesis before the change of tumor color Doppler, and presents different enhanced patterns at different tumor growth times, which corresponded to tumor histologic features.

Significance of microvascular evaluation of ductal lesions on breast ultrasonography: Influence on diagnostic performance

We aim to investigate the significance of microvascular ultrasonography in breast ductal lesions for distinguishing benign from malignant lesions. Sixty-two ductal lesions were evaluated with gray-scale and three Doppler techniques before biopsy, Superb Microvascular Imaging (SMI), color Doppler (CDI), and power Doppler imaging (PDI). We evaluated number, distribution, and morphology of vessels. The area under the ROC curve of combined use of Doppler imaging was greater than that of gray-scale only and SMI had higher value than CDI and PDI (p < 0.05). Microvascular ultrasonography improves diagnostic performance that distinguishes benign from malignant breast ductal lesions, and SMI is superior to CDI and PDI.

First-in-Human Study of Acoustic Angiography in the Breast and Peripheral Vasculature

Screening with mammography has been found to increase breast cancer survival rates by about 20%. However, the current system in which mammography is used to direct patients toward biopsy or surgical excision also results in relatively high rates of unnecessary biopsy, as 66.8% of biopsies are benign. A non-ionizing radiation imaging approach with increased specificity might reduce the rate of unnecessary biopsies. Quantifying the vascular characteristics within and surrounding lesions represents one potential target for assessing likelihood of malignancy via imaging. In this clinical note, we describe the translation of a contrast-enhanced ultrasound technique, acoustic angiography, to human imaging. We illustrate the feasibility of this technique with initial studies in imaging the hand, wrist and breast using Definity microbubble contrast agent and a mechanically steered prototype dual-frequency transducer in healthy volunteers. Finally, this approach was used to image pre-biopsy Breast Imaging Reporting and Data System (BI-RADS) 4 and 5 lesions <2 cm in depth in 11 patients. Results indicate that sensitivity and spatial resolution are sufficient to image vessels as small as 0.2 mm in diameter at depths of ~15 mm in the human breast. Challenges observed include motion artifacts, as well as limited depth of field and sensitivity, which could be improved by correction algorithms and improved transducer technologies.

Vascular Alterations in Axillary and Brachial Vessels in Patients with Axillary Web Syndrome After Breast Cancer Surgery

BACKGROUND

Surgical manipulations of the axilla may cause a condition known as Axillary Web Syndrome (AWS). The systems compromised and the sequence of events leading to this syndrome remains unknown. This study evaluated clinical, surgical, and vascular factors associated with onset and duration of AWS after breast cancer surgery.

METHODS AND RESULTS

In this prospective study, 155 women were included. They were submitted to a physical examination that consisted of ultrasound Doppler of axillary and brachial vessels and the evaluation of AWS in 1, 3, and 6 months after breast cancer surgery. Women with advanced disease had a significantly higher incidence of AWS than those with early stage breast cancer (p = 0.02). In addition, women who underwent mastectomy or axillary lymph node dissection (ALND) had a significantly higher incidence of AWS in the 1-month (p < 0.01; p < 0.01) and 3-months (p < 0.01; p = 0.02) assessment rounds, respectively. The cross-sectional area of brachial artery was significantly smaller (p = 0.04) in women with AWS at the 3-months postoperative visit. The peak systolic velocity and the blood flow of the axillary artery was significantly higher in women with AWS 6 months after surgery (p < 0.03 and p = 0.02 respectively).

CONCLUSION

Our study confirm the combined changes of lymphatic and vascular systems in woman with AWS, since AWS was associated with more extensive dissection of axillary lymph nodes, compromised lymph nodes, and with abnormalities of the vascular parameters.

Modulation of mammary tumor vascularization by mast cells: Ultrasonographic and histopathological approaches

AIMS

The inhibition of mast cells' degranulation may be an approach to prevent the formation of new vessels during the mammary carcinogenesis.

MATERIALS AND METHODS

Female Sprague-Dawley rats were randomly divided into five experimental groups. Mammary tumors were induced by intraperitoneal injection of N-methyl-N-nitrosourea (MNU). Animals from group II were treated with ketotifen for 18weeks immediately after the MNU administration, while animals from group III only received the ketotifen after the development of the first mammary tumor. Mammary tumors vascularization was assessed by ultrasonography (Doppler, B Flow and contrast-enhanced ultrasound) and immunohistochemistry (vascular endothelial growth factor-A).

KEY FINDINGS AND SIGNIFICANCE

Similar to what occurs in women with breast cancer, the majority of MNU-induced mammary tumors exhibited a centripetal enhancement order of the contrast agent, clear margin and heterogeneous enhancement. Ultrasonographic and immunohistochemical data suggest that the inhibition of mast cells' degranulation did not change the mammary tumors vascularization.

Contrast-Enhanced Ultrasound with VEGFR2-Targeted Microbubbles for Monitoring Regorafenib Therapy Effects in Experimental Colorectal Adenocarcinomas in Rats with DCE-MRI and Immunohistochemical Validation

OBJECTIVES

To investigate contrast-enhanced ultrasound (CEUS) with VEGFR2-targeted microbubbles for monitoring therapy effects of regorafenib on experimental colon carcinomas in rats with correlation to dynamic contrast-enhanced MRI (DCE-MRI) and immunohistochemistry.

MATERIALS AND METHODS

Human colorectal adenocarcinoma xenografts (HT-29) were implanted subcutaneously in n = 21 (n = 11 therapy group; n = 10 control group) female athymic nude rats (Hsd: RH-Foxn1rnu). Animals were imaged at baseline and after a one-week daily treatment with regorafenib or a placebo (10 mg/kg bodyweight), using CEUS with VEGFR2-targeted microbubbles and DCE-MRI. In CEUS tumor perfusion was assessed during an early vascular phase (wash-in area under the curve = WiAUC) and VEGFR2-specific binding during a late molecular phase (signal intensity after 8 (SI8min) and 10 minutes (SI10min)), using a conventional 15L8 linear transducer (transmit frequency 7 MHz, dynamic range 80 dB, depth 25 mm). In DCE-MRI functional parameters plasma flow (PF) and plasma volume (PV) were quantified. For validation purposes, CEUS parameters were correlated with DCE-MRI parameters and immunohistochemical VEGFR2, CD31, Ki-67 and TUNEL stainings.

RESULTS

CEUS perfusion parameter WiAUC decreased significantly (116,989 ± 77,048 a.u. to 30,076 ± 27,095a.u.; p = 0.005) under therapy with no significant changes (133,932 ± 65,960 a.u. to 84,316 ± 74,144 a.u.; p = 0.093) in the control group. In the therapy group, the amount of bound microbubbles in the late phase was significantly lower in the therapy than in the control group on day 7 (SI8min: 283 ± 191 vs. 802 ± 460 a.u.; p = 0.006); SI10min: 226 ± 149 vs. 645 ± 461 a.u.; p = 0.009). PF and PV decreased significantly (PF: 147 ± 58 mL/100 mL/min to 71 ± 15 mL/100 mL/min; p = 0.003; PV: 13 ± 3% to 9 ± 4%; p = 0.040) in the therapy group. Immunohistochemistry revealed significantly fewer VEGFR2 (7.2 ± 1.8 vs. 17.8 ± 4.6; p < 0.001), CD31 (8.1 ± 3.0 vs. 20.8 ± 5.7; p < 0.001) and Ki-67 (318.7 ± 94.0 vs. 468.0 ± 133.8; p = 0.004) and significantly more TUNEL (672.7 ± 194.0 vs. 357.6 ± 192.0; p = 0.003) positive cells in the therapy group. CEUS parameters showed significant (p < 0.05) correlations to DCE-MRI parameters and immunohistochemistry.

CONCLUSIONS

CEUS with VEGFR2-targeted microbubbles allowed for monitoring regorafenib functional and molecular therapy effects on experimental colorectal adenocarcinomas with a significant decline of CEUS and DCE-MRI perfusion parameters as well as a significant reduction of specifically bound microbubbles under therapy, consistent with a reduced expression of VEGFR2.

Comparing Quantitative Immunohistochemical Markers of Angiogenesis to Contrast-Enhanced Subharmonic Imaging

OBJECTIVES

Different methods for obtaining tumor neovascularity parameters based on immunohistochemical markers were compared to contrast-enhanced subharmonic imaging (SHI).

METHODS

Eighty-five athymic nude female rats were implanted with 5 × 10(6) breast cancer cells (MDA-MB-231) in the mammary fat pad. The contrast agent Definity (Lantheus Medical Imaging, North Billerica, MA) was injected, and SHI was performed using a modified Sonix RP scanner (Analogic Ultrasound, Richmond, British Columbia, Canada) with a L9-4 linear array (transmitting/receiving frequencies, 8/4 MHz). Afterward, specimens were stained for endothelial cells (CD31), vascular endothelial growth factor (VEGF), and cyclooxygenase 2 (COX-2). Tumor neovascularity was assessed in 4 different ways using a histomorphometry system (×100 magnification: (1) over the entire tumor; (2) in small sub-regions of interest (ROIs); (3) in the tumor periphery and centrally; and (4) in 3 regions of maximum marker expression (so-called hot spots). Results from specimens and from SHI were compared by linear regression.

RESULTS

Fifty-four rats (64%) showed tumor growth, and 38 were successfully imaged. Subharmonic imaging depicted the tortuous morphologic characteristics of tumor neovessels and delineated small areas of necrosis. The immunohistochemical markers did not correlate with SHI measures over the entire tumor area or over small sub-ROIs (P > .18). However, when the specimens were subdivided into central and peripheral regions, COX-2 and VEGF correlated with SHI in the periphery (r = -0.42; P = .005; and r = -0.32; P = .049, respectively).

CONCLUSIONS

When comparing quantitative contrast measures of tumor neovascularity to immunohistochemical markers of angiogenesis in xenograft models, ROIs corresponding to the biologically active region should be used to account for tumor heterogeneity.

Application of a Novel Microvascular Imaging Technique in Breast Lesion Evaluation

Conventional power Doppler imaging (PDI) and the novel Superb Microvascular Imaging (SMI) technique were applied to observe the distribution of microvessels in 135 breast lesions, using semi-quantitative grading, penetrating vessel evaluation and flow distribution pattern to evaluate diagnostic efficacy. Compared with PDI, SMI detected more flow signals and details of microvessels. Further, when a centrally distributed branching or diffusing mode was used as a criterion for diagnosing malignancy, SMI improved diagnosis of breast masses. Sensitivity, specificity, positive predictive value and negative predictive value of SMI-assessed flow distribution were 85.4%, 92.6%, 83.3% and 93.5%, respectively, compared with 70.7%, 92.6%, 80.5% and 87.9% for PDI. We also found that flow distribution pattern analysis is superior to semi-quantitative grading and the penetrating vessel method in differentiating malignant breast lesions. Our work here further supports SMI as a novel and promising technique in visualizing microvasculature in breast lesions that may be of paramount use in initial diagnosis as well as follow-up assessment in various treatment regimes.

Dynamic contrast-enhanced ultrasound parametric maps to evaluate intratumoral vascularization

OBJECTIVES

The purposes of this study were to assess the reliability of parametric maps from dynamic contrast-enhanced ultrasound (DCE-US) to reflect the heterogeneous distribution of intratumoral vascularization and to predict the tissue features linked to vasculature. This study was designed to compare DCE-US parametric maps with histologic vascularity measurements.

MATERIALS AND METHODS

Dynamic contrast-enhanced ultrasound was performed on 17 melanoma-bearing nude mice after a 0.1-mL bolus injection of SonoVue (Bracco SPA, Milan, Italy). The parametric maps were developed from raw linear data to extract pixelwise 2 semiquantitative parameters related to perfusion and blood volume, namely, area under the curve (AUC) and peak intensity (PI). The mathematical method to fit the time-intensity curve for each pixel was a polynomial model used in clinical routine and patented by the team. Regions of interest (ROIs) were drawn on DCE-US parametric maps for whole tumors and for several local areas of 15 mm within each tumor (iROI), the latter reflecting the heterogeneity of intratumoral blood volume. As the criterion standard correlation, microvessel densities (MVDs) were determined for both ROI categories. In detail, for all iROI of 15 mm, MVD and maturity were divided separately for vessels of 0 to 10 μm, 10 to 40 μm, and greater than 40 μm in diameter, and the results were correlated with the ultrasound findings.

RESULTS

Among the 17 studied mice, a total of 64 iROIs were analyzed. For the whole-tumor ROI set, AUC and PI values significantly correlated with MVD (rAUC = 0.52 [P = 0.0408] and rPI = 0.70 [P = 0.0026]). In the case of multiple iROI, a strong linear correlation was observed between the DCE-US parameters and the density of vessels ranging in their diameter from 0 to 10 μm (rAUC = 0.68 [P < 0.0001]; rPI = 0.63 [P < 0.0001]), 10 to 40 μm (rAUC = 0.98 [P = 0.0003]; rPI = 0.98 [P = 0.0004]), and greater than 40 μm (rAUC = 0.86 [P = 0.0120]; rPI = 0.92 [P = 0.0034]), respectively. However, the DCE-US parameter values of perfusion and blood volume were not significantly different according to the diameters (AUC: P = 0.1731; PI: P = 0.2918) and maturity of blood vessels.

CONCLUSIONS

Parametric maps of DCE-US can be reliably established from raw linear data and reflect the heterogeneous histological measures of vascularization within tumors. In contrast, the values of DCE-US parametric maps (AUC, PI) do not allow deduction of heterogeneous tissue features such as the diameters and maturity of vascular networks.

Value of sonographic bidirectional arterial flow combined with elastography for diagnosis of breast imaging reporting and data system category 4 breast masses

OBJECTIVES

The purpose of this study was to evaluate the role of bidirectional arterial flow combined with ultrasound elastography for differentiation of American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) category 4 masses.

METHODS

A total of 116 BI-RADS category 4 breast masses were evaluated with color Doppler sonography, spectral analysis, and elastography. The sensitivity, specificity, accuracy, positive and negative predictive values, and receiver operator characteristic curve were used to estimate the diagnostic performance for each modality and the combination method.

RESULTS

The combination method had the best sensitivity (81.1%) but less specificity (94.9%) and the best accuracy (90.5%). The discriminating power of the combined method (area under the curve [AUC], 0.880; 95% confidence interval [CI], 80.0%-96.0%) was significantly higher than that of bidirectional arterial flow (AUC, 0.818; 95% CI, 72.0%-91.6%; P< .01) and elastography (AUC, 0.765; 95% CI, 65.9%-87.0%; P< .01).

CONCLUSIONS

Bidirectional arterial flow evaluation, when combined with elastography, could potentially improve diagnostic accuracy for BI-RADS category 4 breast masses.

Recent developments in dynamic contrast-enhanced ultrasound imaging of tumor angiogenesis

Angiogenesis is a critical process for tumor growth and metastatic dissemination. There is tremendous interest in the development of noninvasive methods for imaging tumor angiogenesis, and ultrasound (US) is an emerging platform technology to address this challenge. The introduction of intravascular microbubble contrast agents not only allows real-time visualization of tumor perfusion during an US examination, but they can be functionalized with specific ligands to permit molecular US imaging of angiogenic biomarkers that are overexpressed on the tumor endothelium. In this article, we will review current concepts and developing trends for US imaging of tumor angiogenesis, including relevant preclinical and clinicsal findings.

The antiangiogenic effects of a vascular endothelial growth factor decoy receptor can be monitored in vivo using contrast-enhanced ultrasound imaging

The development of antiangiogenic therapies has stimulated interest in noninvasive imaging methods to monitor response. We investigated whether the effects of a vascular endothelial growth factor decoy receptor (VEGF Trap, Regeneron Pharmaceuticals, Tarrytown, NY) could be monitored in vivo using contrast-enhanced ultrasonography (CEUS). Twenty nude mice (in two groups) were implanted with a human melanoma cell line (DB-1). The active group received VEGF Trap (4 × 25 mg/kg over 2 weeks), whereas the control group received an inactive protein. An ultrasound contrast agent was injected followed by power Doppler imaging (PDI) and pulse inversion harmonic imaging (PIHI; regular and intermittent). Specimens were sectioned in the same planes as the images and stained for endothelial cells (CD31), cyclooxygenase-2 (COX-2), VEGF, and hypoxia (Glut1). Measures of tumor vascularity obtained with the different imaging modes were compared to immunohistochemical markers of angiogenesis. Mean tumor volume was smaller in the active group than in the control group (656 ± 225 vs 1,160 ± 605 mm3). Overall, PDI and VEGF correlated (r  =  .34; p =  .037). Vascularity decreased from control to treated mice with intermittent PIHI, as did the expression of CD31 and COX-2 (p ≤ .02), whereas VEGF increased (p  =  .05). CEUS appears to allow in vivo monitoring of the antiangiogenic effects of VEGF Trap in the DB-1 human melanoma xenograft model.

Correlation of ultrasound contrast agent derived blood flow parameters with immunohistochemical angiogenesis markers in murine xenograft tumor models

PURPOSE

In this study we used temporal analysis of ultrasound contrast agent (UCA) estimate blood flow dynamics and demonstrate their improved correlation to angiogenesis markers relative to previously reported, non-temporal fractional vascularity estimates.

MATERIALS AND METHODS

Breast tumor (NMU) or glioma (C6) cells were implanted in either the abdomen or thigh of 144 rats. After 6, 8 or 10 days, rats received a bolus UCA injection of Optison (GE Healthcare, Princeton, NJ; 0.4 ml/kg) during power Doppler imaging (PDI), harmonic imaging (HI), and microflow imaging (MFI) using an Aplio ultrasound scanner with 7.5 MHz linear array (Toshiba America Medical Systems, Tustin, CA). Time-intensity curves of contrast wash-in were constructed on a pixel-by-pixel basis and averaged to calculate maximum intensity, time to peak, perfusion, and time integrated intensity (TII). Tumors were then stained for four immunohistochemical markers (bFGF, CD31, COX-2, and VEGF). Correlations between temporal parameters and the angiogenesis markers were investigated for each imaging mode. Effects of tumor model and implant location on these correlations were also investigated.

RESULTS

Significant correlation over the entire dataset was only observed between TII and VEGF for all three imaging modes (R=-0.35, -0.54, -0.32 for PDI, HI and MFI, respectively; p<0.0001). Tumor type and location affected these correlations, with the strongest correlation of TII to VEGF found to be with implanted C6 cells (R=-0.43, -0.54, -0.52 for PDI, HI and MFI, respectively; p<0.0002).

CONCLUSIONS

While UCA-derived temporal blood flow parameters were found to correlate strongly with VEGF expression, these correlations were also found to be influenced by both tumor type and implant location.

Guidelines and good clinical practice recommendations for Contrast Enhanced Ultrasound (CEUS) in the liver - update 2012: A WFUMB-EFSUMB initiative in cooperation with representatives of AFSUMB, AIUM, ASUM, FLAUS and ICUS

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

Contrast enhanced maximum intensity projection ultrasound imaging for assessing angiogenesis in murine glioma and breast tumor models: A comparative study

The purpose of this study was to prospectively compare noninvasive, quantitative measures of vascularity obtained from four contrast enhanced ultrasound (US) techniques to four invasive immunohistochemical markers of tumor angiogenesis in a large group of murine xenografts. Glioma (C6) or breast cancer (NMU) cells were implanted in 144 rats. The contrast agent Optison (GE Healthcare, Princeton, NJ) was injected in a tail vein (dose: 0.4ml/kg). Power Doppler imaging (PDI), pulse-subtraction harmonic imaging (PSHI), flash-echo imaging (FEI), and Microflow imaging (MFI; a technique creating maximum intensity projection images over time) was performed with an Aplio scanner (Toshiba America Medical Systems, Tustin, CA) and a 7.5MHz linear array. Fractional tumor neovascularity was calculated from digital clips of contrast US, while the relative area stained was calculated from specimens. Results were compared using a factorial, repeated measures ANOVA, linear regression and z-tests. The tortuous morphology of tumor neovessels was visualized better with MFI than with the other US modes. Cell line, implantation method and contrast US imaging technique were significant parameters in the ANOVA model (p<0.05). The strongest correlation determined by linear regression in the C6 model was between PSHI and percent area stained with CD31 (r=0.37, p<0.0001). In the NMU model the strongest correlation was between FEI and COX-2 (r=0.46, p<0.0001). There were no statistically significant differences between correlations obtained with the various US methods (p>0.05). In conclusion, the largest study of contrast US of murine xenografts to date has been conducted and quantitative contrast enhanced US measures of tumor neovascularity in glioma and breast cancer xenograft models appear to provide a noninvasive marker for angiogenesis; although the best method for monitoring angiogenesis was not conclusively established.

Optimizing breast cancer follow-up: diagnostic value and costs of additional routine breast ultrasound

A total of 2,546,325 breast cancer survivors are estimated to live in the United States. The organized breast cancer follow-up programs do not generally include breast ultrasound in asymptomatic women. The purpose of our prospective study was to investigate the efficacy of breast ultrasound in detecting previously occult recurrences. A total of 735 eligible patients with a history of breast cancer were recruited. We assessed the same patient population before (routine follow-up program) and after (study follow-up program) the introduction of an additional ultrasound examination. In the routine follow-up program 245 of 735 patients (33.3% [95% confidence-interval (CI): 29.9-36.7]) had an ultrasound due to abnormal local or mammographic findings. 490 of 735 patients (66.7% [95% CI: 63.3-70.1]) were initially considered asymptomatic and received an additional ultrasound exclusively within the study follow-up program. All positive examination results were followed by accelerated core needle biopsy. The routine follow-up program led to a biopsy in 66 of 735 patients (9.0%) revealing a recurrent cancer in 27 cases (3.7%). The study follow-up program with the additional ultrasound led to another 21 biopsies raising the total number of patients who had to undergo a biopsy from 9.0% (95% CI: 6.9-11.1) to 11.8% (95% CI: 9.5-14.2). Finally, we diagnosed a previously occult malignant lesion in an additional six patients following this protocol. Therefore, the rate of detected recurrences rose from 3.7% (95% CI: 2.3-5.0) in the routine follow-up program to 4.5% (95% CI: 3.0-6.0) in the study follow-up program (p = 0.041). Negative side effects were the additional costs (the costs per detected malignancy in the routine follow-up program were $2455.69; the costs for each additionally detected malignancy in the study follow-up program were $7580.30), the higher overall biopsy rate (9.0 vs. 11.8%) and the elevated benign biopsies rate (59.1% vs. 71.4%). Regarding these results, the advantages and disadvantages of additional breast ultrasound must be discussed for every follow-up patient individually even today, as we can detect a significantly higher number of previously occult malignancies.

Contrast-enhanced ultrasound for molecular imaging of angiogenesis

INTRODUCTION

Molecular imaging of angiogenesis using contrast-enhanced ultrasound allows for functional, real-time, inexpensive imaging of angiogenesis. The addition of stabilized microbubbles as contrast agents greatly improves ultrasound signal to noise ratio/signal strength/image quality (up to 25 dB) and allows for imaging of angiogenic vasculature.

METHODS

In this article recent advances in the usage of contrast-enhanced ultrasound for molecular imaging of angiogenesis are reviewed.

RESULTS

The usage of commercially available agents and correlations between their imaging parameters and molecular markers of angiogenesis are reviewed. Recent developments in ultrasound contrast agents targeted to angiogenic markers for both diagnosis and monitoring are discussed. Finally, a brief overview of the emerging field of chemotherapeutic-loaded agents, which can be used with ultrasound-triggered drug delivery, is provided.

Monitoring angiogenesis in human melanoma xenograft model using contrast-enhanced ultrasound imaging

The potential for noninvasive monitoring and quantification of tumor angiogenesis with contrast-enhanced ultrasound imaging has been investigated in a murine cancer model. Seventy athymic nude mice were implanted with the human melanoma cell line DB-1 but only 30 of these were available for the final study. The 30 mice were divided into three groups (10 mice/group), which were studied with contrast-enhanced ultrasound imaging 4, 5 or 6 weeks post-implantation. Power Doppler and pulse inversion harmonic imaging (PIHI) were performed (in real time and intermittently) with a Sonoline Elegra scanner (Siemens Medical Solutions, Issaquah, WA) following injection of Optison (dose: 0.4-0.6 ml/kg; GE Healthcare, Princeton, NJ). Ultrasound results were compared to immunohistochemical stains for endothelial cells (CD31), vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2). Linear regression analysis indicated statistically significant correlations between the percent area stained with VEGF and ultrasound measures of tumor neovascularity obtained with all three techniques (p < 0.01). Contrast-enhanced ultrasound imaging of tumor neovascularity appears to provide a noninvasive marker of angiogenesis corresponding to the expression of VEGF in the DB-1 model and may become a useful tool for monitoring clinical anti-angiogenic therapies.