Breast tumors: computer-assisted quantitative assessment with color Doppler US

[Quantitative methods in sonography]

B‑mode and color Doppler ultrasound are standard radiological methods to quantify tissue echo texture and tissue perfusion. Microstructure and composition of tissue influence echo texture parameters and acoustic parameters, such as speed of sound, attenuation and backscatter and quantitative color Doppler image parameters are influenced by the hemodynamics in depictable vessels. Dynamic contrast-enhanced ultrasound enables quantification of tissue perfusion and ultrasound elastography assists in assessing tissue stiffness. B‑mode texture analysis, analysis of high-frequency echo signals and quantitative color Doppler image analysis are able to contribute to the assessment of tissue microstructure but have so far not been implemented clinically due to their complexity. Dynamic contrast-enhanced ultrasound and ultrasound elastography have proven to be robust under clinical conditions.

Assessment of Tumor Vascularization: Immunohistochemical and Non-Invasive Methods

Growth of solid tumors beyond a certain mass is dependent on the vascular bed from pre-existing host vasculature. The process of angiogenesis is essential not only for primary tumor growth but also for metastasis. The number of microvessels within the invasive component of a primary tumor reflects the degree of tumor angiogenesis. At present the most widely used method to assess neovascularization is the quantitation of intratumoral microvessel density (IMD) by immunohistochemical methods in which specific markers for endothelial cells are employed. In this paper we analyze the different methods used to assess IMD, as well as their advantages and potential methodological pitfalls. Several studies have shown a close correlation between IMD, tumor growth and the occurrence of metastasis, suggesting that IMD is a prognostic indicator of clinical relevance. Furthermore, preliminary studies suggest that determination of angiogenesis may predict responsiveness to some forms of conventional anticancer therapy. Although the histological microvessel density technique is the current gold standard to characterize tumor angiogenesis, it may not be the ideal tool for clinical purposes because it needs to be performed on biopsy material and does not assess the functional pathways involved in the angiogenic activity of tumors. Non-invasive assessment of tumor vascularity is possible in vivo by means of Doppler sonography, dynamic contrast-enhanced magnetic resonance imaging (MRI) and positron emission tomography (PET). These methods may be preferable to histological assay because they are non-invasive, survey the entire tumor, reflect both anatomic and physiologic characteristics, and may be useful to monitor the activity of antiangiogenic therapies.

Chemoprotection Across the Tumor Border: Cancer Cell Response to Doxorubicin Depends on Stromal Fibroblast Ratios and Interstitial Therapeutic Transport

INTRODUCTION

Increasing evidence suggests that the tumor microenvironment reduces therapeutic delivery and may lead to chemotherapeutic resistance. At tumor borders, drug is convectively transported across a unique microenvironment composed of inverse gradients of stromal and tumor cells. These regions are particularly important to overall survival, as they are often missed through surgical intervention and contain many invading cells, often responsible for metastatic spread. An understanding of how cells in this tumor-border region respond to chemotherapy could begin to elucidate the role of transport and intercellular interactions in relation to chemoresistance. Here we examine the contribution of drug transport and stromal fibroblasts to breast cancer response to doxorubicin using in silico and in vitro models of the tumor-stroma interface.

METHODS

2D culture systems were utilized to determine the effects of modulated ratios of fibroblasts and cancer cells on overall cancer cell viability. A homogenous breast mimetic in vitro 3D collagen I-based hydrogel system, with drug delivered via pressure driven flow (0.5 µm/s), was developed to determine the effects of transport and fibroblasts on doxorubicin treatment efficacy. Using a novel layered tumor bulk-to-stroma transition in vitro 3D hydrogel model, ratios of MDA-MB-231s and fibroblasts were seeded in successive layers creating cellular gradients, yielding insight into region specific cancer cell viability at the tumor border. In silico models, utilizing concentration profiles developed in COMSOL Multiphysics, were optimized for time dependent viability prediction and confirmation of in vitro findings.

RESULTS

In general, the addition of fibroblasts increased viability of cancer cells exposed to doxorubicin, indicating a protective effect of co-culture. More specifically, however, modulating ratios of cancer cells (MDA-MB-231):fibroblasts in 2D co-cultures, to mimic the tumor-stroma transition, resulted in a linear decrease in cancer cell viability from 77% (4:1) to 44% (1:4). Similar trends were seen in the breast-mimetic in vitro 3D collagen I-based homogenous hydrogel system. Our in vitro and in silico tumor border models indicate that MDA-MB-231s at the top of the gel, indicative of the tumor bulk, receive the greatest concentration of drug for the longest time, yet cellular death is lowest in this region. This trend is reversed for MDA-MB-231s alone.

CONCLUSION

Together, our data indicate that fibroblasts are chemoprotective at lower density, resulting in less tumor death in regions of higher chemotherapy concentration. Additionally, chemotherapeutic agent transport properties can modulate this effect.

Role of 3D power Doppler ultrasound in the further characterization of suspicious breast masses

PURPOSE

To investigate effectiveness of vascular indices obtained with 3D power Doppler ultrasound in the further characterization of breast masses and prevention of unnecessary biopsies.

MATERIALS AND METHODS

Between April 2013 and March 2014, 109 patients (age range, 17-85 years; mean age, 47 years) with 117 radiologically or clinically suspicious breast masses were prospectively evaluated with 3DPDUS before biopsy. Mass volume (MV), vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated using Virtual Organ Computer-aided Analysis (VOCAL) software and they were correlated with the final diagnosis. Cutoff values of vascular indices were determinated and diagnostic efficacy was calculated with receiver operating curve (ROC) analysis.

RESULTS

All vascular indices, age of patients and tumor volume were significantly lower in benign masses compared with malignant ones (p<0.001). AUCs were 0.872, 0.867 and 0.789 for VI, VFI and FI, respectively. The diagnostic efficacy of VI (for cutoff 1.1; 83% sensitivity, 82% specificity and 82% accuracy) and VFI (for cutoff 0.4; 80% sensitivity, 83% specificity and 80% accuracy) were significantly higher than FI (for cutoff 33,9; 73% sensitivity, 69% specificity and 71% accuracy). It was found that with the use of vascular indices of 3DPDUS in the further characterization of suspicious breast masses between 24% to 37% of unnecessary biopsies could have been avoided.

CONCLUSION

The vascular indices obtained with 3DPDUS seem reliable in the further characterization of suspicious breast masses and might be used to decrease unnecessary biopsies.

Three-dimensional contrast-enhanced sonography in the assessment of breast tumor angiogenesis: correlation with microvessel density and vascular endothelial growth factor expression

OBJECTIVES

The purpose of this study was to differentiate perfusion and vascular characteristics between benign and malignant breast lesions by 3-dimensional contrast-enhanced sonography and evaluate their correlation with microvessel density and vascular endothelial growth factor (VEGF) expression for further clinical exploration.

METHODS

Three-dimensional contrast-enhanced sonography was performed in 183 patients with breast lesions, and sonographic characteristics were carefully observed for further analysis. The mean microvessel density and VEGF expression were measured by immunohistochemical analysis.

RESULTS

Pathologic results showed 35 benign and 148 malignant cases. Malignancy and benignity differed significantly in peripheral vessel characteristics (number, distribution, course, degree of dilatation, and penetrating vessels), rim perfusion and coarseness degree, intratumoral perfusion type, and intratumoral vessel dilatation (P< .05) but not the presence of peripheral and intratumoral vessels and intratumoral perfusion (P > .05). The specificity of penetrating vessels was 88.6% for diagnosing malignancy. The sensitivity, specificity, and accuracy of rim perfusion coarseness were 90.2%, 70.4%, and 85.3% respectively. The sensitivity of the intratumoral perfusion type was 77.8%, whereas the specificity of intratumoral vessel dilatation was 88.9%. Microvessel density and VEGF expression were significantly correlated with perfusion and vascular characteristics (P < .05), except the presence of peripheral vessels, rim perfusion, and intratumoral perfusion (P> .05). The presence of intratumoral vessels was related to VEGF (P< .05) but not microvessel density (P > .05).

CONCLUSIONS

Three-dimensional contrast-enhanced sonographic characteristics were statistically different between benign and malignant breast lesions. Some of them also correlated significantly with microvessel density and VEGF expression and therefore have potential for objective evaluation of tumor angiogenesis.

An ideal blood mimicking fluid for doppler ultrasound phantoms

In order to investigate the problems of detecting tumours by ultrasound it is very important to have a portable Doppler flow test object to use as a standardising tool. The flow Doppler test objects are intended to mimic the flow in human arteries. To make the test meaningful, the acoustic properties of the main test object components (tissue and blood mimic) should match closely the properties of the corresponding human tissues, while the tube should ideally have little influence. The blood mimic should also represent the haemodynamic properties of blood. An acceptable flow test object has been designed to closely mimic blood flow in arteries. We have evaluated the properties of three blood mimicking fluid: two have been described recently in the literature, the third is a local design. One of these has emerged as being particularly well matched to the necessary characteristics for in-vitro work.

Breast Sonography - 2D, 3D, 4D Ultrasound or Elastography?

SUMMARY: The aim of this publication is to give an answer to the question whether 2D, 3D and 4D sonography of the breast can be replaced by elastography or whether elastography is an adjunct tool to B-mode imaging. The Breast Imaging and Reporting Data System (BI-RADS) ultrasound (US) descriptors of a lesion besides vascularity are based on B-mode imaging. US elastography displays the mechanical tissue properties. This information can be obtained by freehand compression and decompression. Acoustic radiation force impulse imaging (ARFI) produces stress with low-frequency push pulses. Manual compression by the transducer is not necessary. Shear wave elastography (SWE) is the combination of ARFI and the measurement of the consecutive shear wave propagations in the tissue. A quantification of the elasticity in kilopascal (kPa) is offered. Discussing B-mode imaging and elastography combined with the literature, elastography is seen as an addition to B-mode imaging with the potential to increase the specificity of the B-mode imaging-based BI-RADS assessment. In spite of additional elasticity information, the sensitivity remains high. A time-saving diagnostic algorithm for 2D, 3D US and elastography is described. In conclusion, it must be said that elasticity is not a stand-alone US modality able to replace 2D and 3D sonography.

Multimodality computer-aided breast cancer diagnosis with FFDM and DCE-MRI

RATIONALE AND OBJECTIVES

To investigate a multimodality computer-aided diagnosis (CAD) scheme that combines image information from full-field digital mammography (FFDM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for computerized breast cancer classification.

MATERIALS AND METHODS

From a retrospective FFDM database with 432 lesions (255 malignant, 177 benign) and a retrospective DCE-MRI database including 476 lesions (347 malignant, 129 benign), we constructed a multimodality dataset of 213 lesions (168 malignant, 45 benign). Each lesion was present on both FFDM and DCE-MRI images and deemed to be a difficult case given the necessity of having both clinical imaging exams. Using a manually indicated lesion location (ie, a seed point on FFDM images or a region of interest on DCE-MRI images, the computer automatically segmented the mass lesions and extracted lesion features). A subset of features was selected using linear stepwise feature selection and merged by a Bayesian artificial neural network to yield an estimate of the probability of malignancy. Receiver operating characteristic (ROC) analysis was used to evaluate the performance of the selected features in distinguishing between malignant and benign lesions.

RESULTS

With leave-one-lesion-out cross-validation on the multimodality dataset, the mammography-only features yielded an area under the ROC curve (AUC) of 0.74 +/- 0.04, and the DCE-MRI-only features yielded an AUC of 0.78 +/- 0.04. The combination of these two modalities, which included a spiculation feature from mammography and two kinetic features from DCE-MRI, yielded an AUC of 0.87 +/- 0.03. The improvement of combining multimodality information was statistically significant as compared to the use of single modality information alone.

CONCLUSIONS

A CAD scheme that combines features extracted from FFDM and DCE-MRI images may be advantageous to single-modality CAD in the task of differentiating between malignant and benign lesions.

Quantification of left to right shunt in patent ductus arteriosus by color Doppler

Ultrasound is a reliable tool to diagnose patent ductus arteriosus in premature infants but no reliable noninvasive method exists to quantify ductal flow. The aim of this study was to quantify the size of the shunt via persistent ductus arteriosus from pixel counts in color Doppler flow images. A cotton band was placed around the ductus arteriosus of newborn lambs to adjust the magnitude of flow. For flow measurements, ultrasonic transit time flow probes were applied around the ascending aorta and ductus arteriosus. Twenty-four different flow states were attained in four newborn lambs. An Acuson Sequoia scanner equipped with a 7 MHz transducer was used to register Doppler data and images with maximal color distribution during diastole in the pulmonary artery longitudinal sections (PALS). Each image-pixel was matched with the color velocity bar and the pixels were assigned to the corresponding flow velocity. The total area showing color relative to the area of the PALS correlated well with the amount of ductal flow (r = 0.87, r(2) = 0.75, p < 0.001). When Qp/Qs was >1.4:1, more than 40% of the area in PALS in diastole exhibited color information. Similarly, the color pixel velocities squared correlated with the size of the shunt. Quantification of the percentage of pixels in a color Doppler registration via a computer-based analysis shows a high correlation with the size of ductal shunting.

Suspicious breast lesions: assessment of 3D Doppler US indexes for classification in a test population and fourfold cross-validation scheme

PURPOSE

To assess the diagnostic performance of various Doppler ultrasonographic (US) vascularity measures in conjunction with grayscale (GS) criteria in differentiating benign from malignant breast masses, by using histologic findings as the reference standard.

MATERIALS AND METHODS

Institutional Review Board and HIPAA standards were followed. Seventy-eight women (average age, 49 years; range, 26-70 years) scheduled for breast biopsy were included. Thirty-eight patient scans were partially analyzed and published previously, and 40 additional scans were used as a test set to evaluate previously determined classification indexes. In each patient, a series of color Doppler images was acquired and reconstructed into a volume encompassing a suspicious mass, identified by a radiologist-defined ellipsoid, in which six Doppler vascularity measures were calculated. Radiologist GS ratings and patient age were also recorded. Multivariable discrimination indexes derived from the learning set were applied blindly to the test set. Overall performance was also confirmed by using a fourfold cross-validation scheme on the entire population.

RESULTS

By using all cases (46 benign, 32 malignant), the area under the receiver operating characteristic curve (A(z)) values confirmed results of previous analyses: Speed-weighted pixel density (SWPD) performed the best as a diagnostic index, although statistical significance (P = .01) was demonstrated only with respect to the normalized power-weighted pixel density. In both learning and test sets, the three-variable index (SWPD-age-GS) displayed significantly better diagnostic performance (A(z) = 0.97) than did any single index or the one two-variable index (age-GS) that could be obtained without the data from the Doppler scan. Results of the cross validation confirmed the trends in the two data sets.

CONCLUSION

Quantitative Doppler US vascularity measurements considerably contribute to malignant breast tissue identification beyond subjective GS evaluation alone. The SWPD-age-GS index has high performance (A(z) = 0.97), regardless of incidental performance variations in its single variable components.

Clinical biomarkers of angiogenesis inhibition

INTRODUCTION

An expanding understanding of the importance of angiogenesis in oncology and the development of numerous angiogenesis inhibitors are driving the search for biomarkers of angiogenesis. We review currently available candidate biomarkers and surrogate markers of anti-angiogenic agent effect.

DISCUSSION

A number of invasive, minimally invasive, and non-invasive tools are described with their potential benefits and limitations. Diverse markers can evaluate tumor tissue or biological fluids, or specialized imaging modalities.

CONCLUSIONS

The inclusion of these markers into clinical trials may provide insight into appropriate dosing for desired biological effects, appropriate timing of additional therapy, prediction of individual response to an agent, insight into the interaction of chemotherapy and radiation following exposure to these agents, and perhaps most importantly, a better understanding of the complex nature of angiogenesis in human tumors. While many markers have potential for clinical use, it is not yet clear which marker or combination of markers will prove most useful.

Intra-tumor flow index can predict the malignant potential of breast tumor: dependent on age and volume

The aim of this study was to assess tumor vascularity through three dimensional (3D) power Doppler breast ultrasound (US) and propose a decision model for the classification of benign and malignant breast tumors. Patient recruitment for this study was performed consecutively during a 13-mo period (January 2003 to February 2004). A total of 102 benign and 93 malignant solid breast images were analyzed. Three-dimensional power Doppler US imaging was performed using a Voluson730 ultrasound system equipped with a relative stopping power index (RSP) 6 to 12 transducer. The Virtual Organ Computer-aided Analysis (VOCAL)-imaging program (version 2.1) was used to analyze the stored volume. Histogram indices of the vascularization index (VI), flow index (FI) and vascularization-flow index (VFI) for the intra-tumor and for shells with a thickness of 3 mm surrounding the breast lesion were calculated and showed that for both, malignancy had a higher VI, FI and VFI than benignancy, with statistical significance. Multivariate and stepwise logistic regression revealed the model (including patient age, volume and intra-tumor FI in 3D power Doppler vascularity) to be the best choice for malignant breast tumor characterization. The receiver operating characteristics (ROC) index for the performance of the model was 0.926. Histogram indices for the intra-tumor FI in the 3D power Doppler scan are a good choice of parameter for differentiating between malignant and benign tumors with respect to the power of sensitivity, no matter whether one index is suggested or the patients' age and volume are considered.

Diagnostic algorithm: How to make use of new 2D, 3D and 4D ultrasound technologies in breast imaging

The aim of this publication is to present a time saving diagnostic algorithm consisting of two-dimensional (2D), three-dimensional (3D) and four-dimensional (4D) ultrasound (US) technologies. This algorithm of eight steps combines different imaging modalities and render modes which allow a step by step analysis of 2D, 3D and 4D diagnostic criteria. Advanced breast US systems with broadband high frequency linear transducers, full digital data management and high resolution are the actual basis for two-dimensional breast US studies in order to detect early breast cancer (step 1). The continuous developments of 2D US technologies including contrast resolution imaging (CRI) and speckle reduction imaging (SRI) have a direct influence on the high quality of three-dimensional and four-dimensional presentation of anatomical breast structures and pathological details. The diagnostic options provided by static 3D volume datasets according to US BI-RADS analogue assessment, concerning lesion shape, orientation, margin, echogenic rim sign, lesion echogenicity, acoustic transmission, associated calcifications, 3D criteria of the coronal plane, surrounding tissue composition (step 2) and lesion vascularity (step 6) are discussed. Static 3D datasets offer the combination of long axes distance measurements and volume calculations, which are the basis for an accurate follow-up in BI-RADS II and BI-RADS III lesions (step 3). Real time 4D volume contrast imaging (VCI) is able to demonstrate tissue elasticity (step 5). Glass body rendering is a static 3D tool which presents greyscale and colour information to study the vascularity and the vascular architecture of a lesion (step 6). Tomographic ultrasound imaging (TUI) is used for a slice by slice documentation in different investigation planes (A-,B- or C-plane) (steps 4 and 7). The final step 8 uses the panoramic view technique (XTD-View) to document the localisation within the breast and to make the position of a lesion simply reproducible.

Value of contrast-enhanced ultrasound and elastography in imaging of prostate cancer

PURPOSE OF REVIEW

Prostate cancer is the most commonly diagnosed malignancy in men. Gray-scale ultrasound-guided systematic biopsy is the standard of care for prostate cancer detection in men with an elevated prostate-specific antigen or an abnormal digital rectal examination. Systematic biopsy may miss up to 35% of clinically relevant cancers. Color and power Doppler ultrasound, ultrasound contrast agents, and elastography have and will dramatically change the role of ultrasound in prostate cancer diagnosis.

RECENT FINDINGS

Several reports have demonstrated that contrast-enhanced ultrasound investigations of the blood flow of the prostate allow for prostate cancer visualization and therefore, for targeted biopsies. Comparisons between systematic and contrast-enhanced ultrasound-targeted biopsies have shown that the targeted approach detects more cancers with a lower number of biopsy cores. Furthermore, contrast-enhanced ultrasound has been shown to detect cancers with higher Gleason scores compared with the systematic approach, which seems to improve prostate cancer grading. In addition, elastography is a new ultrasound technique that allows for the assessment of tissue elasticity.

SUMMARY

Contrast-enhanced ultrasound and elastography improve prostate cancer detection and may be useful for prostate cancer grading and staging. Future clinical trials will be needed to determine the promise of these new advances for ultrasound of the prostate evolving into clinical applications.

A review of breast ultrasound

Frequent advances in transducer design, electronics, computers, and signal processing have improved the quality of ultrasound images to the extent that sonography is now a major mode of imaging for the clinical diagnosis of breast cancer. Breast ultrasound is routinely used for differentiating cysts and solid nodules with high specificity. In combination with mammography, ultrasound is used to characterize solid masses as benign or malignant. There is growing interest in using Doppler ultrasound and contrast agents for measuring tumor blood flow and for imaging tumor vascularity. Ease of use and real-time imaging capability make breast ultrasound a method of choice for guiding breast biopsies and other interventional procedures. Breast ultrasound is used in many forms. B-mode is the most common form of imaging for the breast, although compound imaging and harmonic imaging are being increasingly applied to better visualize breast lesions and to reduce image artifacts. These developments, together with the formulation of a standardized lexicon of solid mass features, have improved the diagnostic performance of breast ultrasound. Several approaches that are currently being investigated to further improve performance include: (1) computer-aided-diagnosis; (2) the assessment of tumor vascularity and tumor blood flow with Doppler ultrasound and contrast agents; and (3) tissue elasticity imaging. In the future, ultrasound will play a greater role in differentiating benign from malignant masses and in the diagnosis of breast cancer.

Prostate ultrasound--for urologists only?

The value of ultrasound (US) in the diagnosis of prostate cancer has dramatically increased in the past decade. This is mainly related to the increasing incidence of prostate cancer, the most common cancer in men and one of the most important causes of death from cancer in men. The value of conventional gray-scale US for prostate cancer detection has been extensively investigated, and has shown a low sensitivity and specificity. Therefore conventional gray-scale US is mainly used by urologists for guiding systematic prostate biopsies. With the development of new US techniques, such as color and power Doppler US, and the introduction of US contrast agents, the role of US for prostate cancer detection has dramatically changed. Advances in US techniques were introduced to further increase the value of US contrast agents. Although most of these developments in US techniques, which use the interaction of the contrast agent with the transmitted US waves, are very sensitive for the detection of microbubbles, they are mostly unexplored, in particular for prostate applications. Early reports of contrast-enhanced US investigations of blood flow of the prostate have shown that contrast-enhanced US adds important information to the conventional gray-scale US technique. Furthermore, elastography or ‘strain imaging’ seems to have great potential in prostate cancer detection. Since these new advances in US are very sophisticated and need a long learning curve, radiologists, who are overall better trained with these new US techniques, will play a more important role in prostate cancer diagnosis. Current trends show that these new US techniques may allow for targeted biopsies and therefore replace the current ‘gold standard’ for prostate cancer detection—the systematic biopsy. Consequently the use of these new US techniques for the detection and clinical staging of prostate cancer is promising. However, future clinical trials will be needed to determine if the promise of these new US advances of the prostate evolves into clinical application.

Computer-assisted quantitative assessment of power Doppler US: effects of microbubble contrast agent in the differentiation of breast tumors

RATIONALE AND OBJECTIVES

To objectively quantify the effects of a microbubble contrast agent to differentiate breast tumors with power doppler ultrasound and to compare these results with color doppler ultrasound (CD US).

METHODS

In 47 patients a microbubble contrast agent was injected intravenously. Computer-assisted quantitative assessment of the color pixel density was performed to evaluate the increase in Doppler signals. Results were compared to previously published results of a color Doppler ultrasound study.

RESULTS

Peak color pixel density at contrast-enhanced power Doppler ultrasound was higher for carcinomas than for benign tumors (P < 0.03). Time to peak enhancement was shorter in carcinomas than in benign tumors (P < 0.01). For both parameters, diagnostic accuracy of power Doppler ultrasound was 69 and 78%, and for color Doppler ultrasound 62 and 76%, respectively.

CONCLUSIONS

Quantitative assessment of contrast-enhanced power Doppler ultrasound showed significant differences in malignant and benign breast tumors. Diagnostic accuracy of contrast-enhanced power Doppler ultrasound was higher compared to color Doppler ultrasound.

Hormonal variations in the vascularity of breast tissue

OBJECTIVE

The purpose of this study was to determine whether there are sonographically detectable variations in breast glandularity and vascularity due to hormonal changes during the course of a normal menstrual cycle.

METHODS

Gray scale and color and power Doppler sonographic evaluations were performed on 7 premenopausal patients over the course of 1 menstrual cycle. Progesterone and estradiol levels were measured from saliva collected from the patients. Vascularity was measured by mean color level, area covered by color pixels, and color-weighted fractional area.

RESULTS

Of the 5 volunteers not taking oral contraceptives, 4 had peaks in vascularity correlating with midcycle peak hormonal levels (50%-320% from baseline) on power Doppler sonography. On color Doppler sonography, 3 of 5 patients also had peaks in vascularity (60%-190% from baseline). The 2 patients taking oral contraceptives did not have any peaks in vascularity.

CONCLUSIONS

Vascularity changes in normal breast tissue that correlated with peak hormonal levels were detected in most of the volunteers. Therefore, hormonal variations in breast vascularity should be considered when evaluating breast lesions by sonography.

[Breast cancer. Sonography and magnetic resonance mammography]

Breast cancer is the most common malignant tumor in women: Almost 10% will suffer from breast cancer during their life; almost half of these will die of it. The spectrum of radiologic methods for diagnosing breast cancer is wide, including X-ray mammography, ultrasound, magnetic resonance mammography, and minimally invasive biopsies. This second part of two covers ultrasound of the breast and magnetic resonance mammography.

Correlation between Doppler vascular density and PSA response to radiation therapy in patients with localized prostate carcinoma

RATIONALE AND OBJECTIVES

The authors performed this study to ascertain whether there is a correlation between pretreatment Doppler vascular density (DVD) of the prostate and prostate-specific antigen (PSA) response following radiation therapy in prostate cancer patients.

MATERIALS AND METHODS

Prior to radiation therapy, 14 patients with biopsy-proven carcinoma (of Gleason grades 2-7) were imaged with transrectal ultrasound in gray-scale, color Doppler, and power Doppler modes. The Doppler images were analyzed for mean DVD with the aid of a computer program. PSA levels were measured before therapy and every 3 months after therapy. The PSA measurements were fitted to an exponential to determine PSA halving time (T1/2). Correlations were made between T1/2 and the following pretherapy measurements: mean DVD, PSA level, prostate volume, and Gleason grade.

RESULTS

Median follow-up time was 392 days. A linear correlation with regression coefficient (R) of 0.75-0.80 was observed between mean DVD and T1/2 for color Doppler and power Doppler imaging. In both imaging modes, each percentage increase in mean DVD led to an increase in T1/2 by 25 days. Pretherapy prostate volume, PSA level, and Gleason score did not correlate with T1/2.

CONCLUSION

The pretreatment mean DVD correlates inversely with the rate of posttherapy decline in PSA in patients with prostate cancer. That is, pretreatment vascularity prognosticates postirradiation PSA response. The mechanism underlying this correlative relationship is not known.

Role of color and power doppler imaging in differentiating between malignant and benign solid breast masses

PURPOSE

This study analyzed the color and power Doppler signals in solid breast masses and assessed their value in differentiating malignant from benign lesions.

METHODS

One hundred twenty-nine biopsy-proven solid breast masses (54 malignant and 75 benign) were evaluated with color and/or power Doppler sonography using a 7-MHz linear-array transducer. We retrospectively analyzed the location, shape, and penetration of the Doppler vascular signals in the breast masses. The location of the vascular signals was categorized as central, peripheral, or both. The shape of the signals was categorized as linear, irregular, branching, or a single dot. A penetrating vessel was defined as a continuous vascular signal extending from outside the lesion to inside it. In 43 cases, power and color Doppler sonograms were compared.

RESULTS

Doppler features suggestive of malignant lesions were the presence of both peripheral and central vascularity (odds ratio, 6.0), presence of penetrating vessels (odds ratio, 5.4), and presence of branching vessels (odds ratio, 13.7). Power Doppler sonography was more sensitive than color Doppler sonography in detecting vascular signals in 49% of cases.

CONCLUSIONS

Color (power) Doppler imaging is a valuable adjunct to conventional sonography in differentiating between malignant and benign breast lesions.

Texture analysis of lesions in breast ultrasound images

We investigate the use of Haralick's texture features and posterior acoustic attenuation descriptors (PAAD) for the characterization of ultrasound (US) breast lesions. 71 lesions (24 cyst, 21 benign solid mass and 26 malignant solid masses) were manually segmented on two-dimensional breast US images. 28 Haralick's descriptors and two PAAD were evaluated on these segmented lesions. Mean of Sum Average, Range of Sum Entropy and the second PAAD best discriminated cysts from noncysts. Range of Correlation and the second PAAD best discriminated solid malignant from benign lesions. Computerized analysis of breast US images can increase the specificity of breast sonography by providing a better characterization of solid lesions.

Differentiation of breast masses using 3-D sonographic and echo-enhancer-based evaluation of the vascular pattern: initial experiences

To evaluate the potential of combined 3-D B-mode and color Doppler (CD) data sets in the differentiation of breast masses, in 50 patients with histologically proven solid breast lesions, 3-D datasets were acquired. A 3-D display was created and volume calculation of tumors, their periphery and vasculature was performed. Time-intensity curves of enhancement after administration of a contrast agent were analyzed. Volumetry of tumor vasculature yielded no significant differences between malignant and benign tumors regarding vascularization of the center (2.60 vs. 2.88%) and periphery (6.66 vs. 3.78%). Only the mean values for the rise time in the center of the tumor, fibroadenoma (FA): 5.7 s and ductal invasive carcinoma (DIC): 15.8s; p = 0.05, and the time to peak in the periphery, FA: 21.0 s and DIC: 31.6 s; p = 0.03, differed significantly. The 3-D ultrasound (US) technique was of no additional value in differentiating breast masses. The calculation of time-intensity curves after administration of a contrast agent may be helpful in differentiating FA and DIC.

Advances in ultrasound for the detection of prostate cancer

The introduction of ultrasound (US) microbubble contrast agents has dramatically expanded the possibilities for US detection of prostate cancer. Recent advances in US technology have increased the value of US contrast agents. Many newer US techniques, which are quite sensitive for detection of microbubbles, are yet to be explored for prostate applications. A critical evaluation of the current status of transrectal US imaging for the detection of prostate cancer and background information for US contrast agents and imaging techniques are presented. Early results have demonstrated the feasibility of US contrast agents to enhance US imaging of prostatic disease. The application of US contrast agents for the detection and clinical staging of prostate cancer is promising. Future clinical trials are needed to determine whether the promise of contrast-enhanced US of the prostate will evolve into widespread clinical application.

Intra-tumoural microvessel density in human solid tumours

Over the last decade assessment of angiogenesis has emerged as a potentially useful biological prognostic and predictive factor in human solid tumours. With the development of highly specific endothelial markers that can be assessed in histological archival specimens, several quantitative studies have been performed in various solid tumours. The majority of published studies have shown a positive correlation between intra-tumoural microvessel density, a measure of tumour angiogenesis, and prognosis in solid tumours. A minority of studies have not demonstrated an association and this may be attributed to significant differences in the methodologies employed for sample selection, immunostaining techniques, vessel counting and statistical analysis, although a number of biological differences may account for the discrepancy. In this review we evaluate the quantification of angiogenesis by immunohistochemistry, the relationship between tumour vascularity and metastasis, and the clinicopathological studies correlating intra-tumoral microvessel density with prognosis and response to anti-cancer therapy. In view of the extensive nature of this retrospective body of data, comparative studies are needed to identify the optimum technique and endothelial antigens (activated or pan-endothelial antigens) but subsequently prospective studies that allocate treatment on the basis of microvessel density are required.

Strong impact of estrogen environment on Doppler variables used for differentiation between benign and malignant breast lesions

OBJECTIVES

To analyze the impact of an estrogen environment on the Doppler variables usually used for differentiation between benign and malignant lesions.

METHODS

A total of 142 malignant and 107 benign breast lesions was demonstrated (in 91 premenopausal and 152 postmenopausal patients) by B-mode ultrasound. Intratumoral vessels were visualized by color Doppler and blood flow velocity waveforms were analyzed by pulsed Doppler. The number of intratumoral vessels and the Doppler variables, peak systolic velocity, resistance and pulsatility indices and the peak systolic/diastolic ratio were evaluated in different endocrine milieus represented by menopausal status, phase of the menstrual cycle, intake of oral contraceptives or hormone replacement therapy.

RESULTS

In malignant tumors the Doppler variables resistance and pulsatility indices and the systolic/diastolic ratio were significantly higher in postmenopausal women than in premenopausal women. In benign tumors significantly higher values of resistance and pulsatility indices were also detected in post- compared to premenopausal women (P < or = 0.05). In premenopausal patients with benign tumors taking oral contraceptives the number of intratumoral vessels was significantly higher, while resistance index and systolic/diastolic ratio values were decreased compared to patients with spontaneous menstrual cycles. In postmenopausal patients hormone replacement therapy did not influence Doppler variables in the benign or the malignant groups.

CONCLUSION

Our results demonstrate a robust influence of menopausal status and oral contraceptives on Doppler variables of breast lesions. We believe it is likely that some of the differences in the Doppler variables found in reports comparing benign and malignant breast lesions were caused by their association with a pre- or postmenopausal status.

Technique of color Doppler quantification of vascularity in transplanted kidneys

A new technique for the quantification of vascularity based on the analysis of color Doppler images is described. We utilized velocity information obtained directly from cineloops transferred to a computer for off-line analysis. This methodology was used in transplanted kidneys to assess parenchymal vascularity on the basis of percentage color pixel density and mean flow velocity in mid-kidney cross-sectional regions of interest and the distance from the most peripheral color pixels to the capsule of the kidney. Other color Doppler quantitative methods have lacked reproducibility, and therefore before evaluation of the clinical usefulness of this technique, intraobserver reproducibility and interobserver reliability were assessed in 42 patients; no statistically significant variation was demonstrated. In 13 patients with normally functioning transplants, the mean maximum color pixel density was 34.7+/-13.4%, the mean flow velocity was 5.2+/-0.9 cm/second, and the mean distance to the capsule was 3.3+/-1.1 mm.

Changes of tumor vascularity during gene therapy monitored with color Doppler US

Using contrast-enhanced color Doppler (CD) sonography, we assessed alterations of tumor blood flow induced in 25 murine Morris hepatomas transfected with a gancyclovir- (GCV-)sensitizing Herpes simplex virus thymidine kinase (HSVtk) suicide gene in combination with systemic GCV treatment and compared findings with a control tumor. CD measurements were quantified by the color pixel density (CPD) and the mean encoded flow velocity (mean color value, MCV), using computer-assisted image analysis, and compared with histologic arteriole counts. During 5 days, the tumor volume remained constant. In HSVtk-expressing tumors, the median CPD dropped from 16% at baseline to 5% on day 5 (p = 0.001), remaining constant in controls. The MCV decreased from 1.9 cm/s to 1.6 cm/s in the HSVtk-expressing tumors (p = 0.001) and rose from 1.8 cm/s to 2.0 cm/s in the controls (p = 0.002). In an accompanying histologic arteriole assay, we found no alterations attributable to treatment.

Color Doppler sonography of the lateral thoracic (breast-feeding) arteries: a new approach to the diagnosis of breast disease?

OBJECTIVE

The main arteries to the breast are the lateral thoracic artery and to a lesser extent the internal thoracic artery. In this prospective open diagnostic study involving 94 women, we compared the intraindividual differences of Doppler indices in the lateral thoracic (breast-feeding) artery of breasts affected by cancer with those unaffected by disease.

METHODS

Sixty-seven consecutive patients were recruited from an outpatient unit for breast surgery and 27 volunteers were studied who were known to be without any breast disease (controls). In each patient we attempted to obtain Doppler indices from the lateral thoracic artery of both breasts. The difference in Doppler indices in each individual was assessed and statistical analysis was performed to assess whether these differences were significantly altered in women with cancer compared to healthy women.

RESULTS

Lateral thoracic arteries could be visualized in 88% of the study population. Significantly lower values for pulsatility and resistance indices and systolic/diastolic ratios were obtained in the lateral thoracic arteries of breasts affected by cancer as compared to the contralateral breasts (1.73 +/- 0.39 vs. 2.05 +/- 0.47, P = 0.003; 0.78 +/- 0.06 vs. 0.84 +/- 0.06, P < 0.0001; 4.71 +/- 1.24 vs. 6.75 +/- 3.38, P = 0.0008, respectively). Using the intraindividual difference of pulsatility index, resistance index and systolic/diastolic ratio to screen for malignancy, sensitivities for breast cancer of 78%, 85% and 83%, respectively, were achieved. Depending on the cut-off level, specificity reached 94%.

CONCLUSION

The intraindividual difference in Doppler indices in women with breast cancer may be a useful test for the diagnosis of breast lesions.

Renal blood flow changes induced with endothelin-1 and fenoldopam mesylate at quantitative Doppler US: initial results in a canine study

PURPOSE

To evaluate quantitative Doppler ultrasonography (US) for assessing renal blood flow changes induced with endothelin-1 (ET-1) and fenoldopam mesylate in conscious dogs.

MATERIALS AND METHODS

A blood flow probe was surgically implanted around the renal artery in eight adult dogs. Color and power Doppler US images were acquired in conscious restrained dogs during intravenous infusion of ET-1 and fenoldopam mesylate. Simultaneous with imaging, blood flow through the renal artery was measured with the implanted probe. The color level of the images within the region representing the kidney was analyzed to derive flow indices. These indices were compared with direct-flow measurements.

RESULTS

The flow indices, color-weighted flow area (CWFA), and percentage of area of color, derived from color and power Doppler US images, correlated linearly with direct flow. The mean color level of color and power Doppler US images correlated weakly with direct flow. Pre- versus postinfusion CWFA decreased with all ET-1 infusions (P < or =.032). Infusion of fenoldopam mesylate increased CWFA in all cases (P < or =.032).

CONCLUSION

Quantitative Doppler US enabled successful measurement of the flow changes induced with ET-1 and fenoldopam mesylate. Quantitative Doppler US is potentially useful as a noninvasive surrogate endpoint in evaluating the action of various therapeutic agents.

Fibroadenomas: computer-assisted quantitative evaluation of contrast-enhanced power Doppler features and correlation with histopathology

We aimed to evaluate whether the histopathologic variability of fibroadenomas accounts for their varied appearance in contrast enhanced power Doppler (PD). Forty patients with fibroadenomas (aged 19 to 61 years) underwent power Doppler ultrasound (US) prior to and following IV bolus injection of a microbubble contrast agent. A 3-min computer-assisted assessment of the color pixel density (CPD) was used for objective evaluation of the increase in color Doppler signals. Enhancement characteristics were correlated to histopathologic features of microvessel density and epithelial hyperplasia, patient's age, tumor size, use of exogenous hormones and menopausal status. Epithelial hyperplasia was diagnosed in 19 patients. Compared to baseline values, patients with epithelial hyperplasia showed a significant increase in mean CPD following contrast media administration (p < 0.01). There was a significant correlation to patient's age (p < 0.0001) and tumor size (p < 0.0001), but not to the use of exogenous hormones and menopausal status. Microvessel counts did not show a significant correlation to CPD at baseline (p = 0.07) or with CPD on contrast enhanced PD (p = 0.13), or with patient age (p = 0.43) or tumor size (p = 0.34). Intratumoral epithelial hyperplasia, primarily occurring in young patients, may contribute to the differential diagnostic overlap in some fibroadenomas and thus limit the ability of PD to distinguish between benign and malignant masses on the basis of enhancement characteristics.

Use of Doppler ultrasound in the evaluation of breast carcinoma

Ultrasound is an imaging modality commonly used to evaluate breast lesions in hopes to distinguish benign from malignant solid masses. Angiogenesis, defined as the emergence of new vessels to further the growth of tumor, has stimulated interest in the potential uses of Doppler ultrasound in patients with breast cancer. This article describes different forms of Doppler ultrasound, including color Doppler (CD), power Doppler (PD), and spectral Doppler (SD), as well as 3-dimensional (3D) ultrasound and ultrasound contrast media. We review the role of Doppler ultrasound in distinguishing benign from malignant solid breast masses. We also discuss the role of ultrasound in predicting tumor grade, histology, node status, and lymphatic vascular invasion, and in monitoring breast cancer treatment.

The evolving role of sonography in evaluating solid breast masses

Many investigators have attempted to use ultrasound imaging to differentiate benign from malignant solid breast masses. Studies have evaluated several generations of gray-scale imaging, Doppler, color Doppler, and power Doppler imaging, and several unconventional ultrasound techniques. Although various individual studies have shown promise, ultrasound criteria for avoiding biopsy of solid lesions have not been widely adopted. Considerable observer variability also remains an important obstacle. This article reviews the results, strengths, and weaknesses of some of the key studies addressing this issue. Fundamental criteria for a successful ultrasound model are also specified.

An objective characterization of atherosclerotic lesion: an alternative method to identify unstable plaque

BACKGROUND AND PURPOSE

The aim of this study was to evaluate a computer-assisted technique to characterize atherosclerotic plaque.

METHODS

In 9 subjects (7 men, 2 women; mean age 33 years), known anatomic areas (carotid, fat, muscle, iliotibial tract, and tibia) were scanned with an Acuson duplex ultrasound machine with 72 machine settings. The ultrasound images of these anatomic areas were recorded on magneto-optical disks. Echo amplitude statistics were obtained, and the mean pixel value (MPV) was used to assess the level of echogenicity. The ideal settings of this particular scanner for optimal discrimination between these tissues types were identified by the Heuristic Index of Discrimination. With these settings, carotid artery scanning was performed on 17 patients (15 men, 2 women; mean age 65 years), and the image analysis of their ultrasound carotid plaques was compared with their histological findings.

RESULTS

In this study, discrimination between the selected tissues was found to be optimal when the controls were set at log 40 dB, 0/2/0, and gain of -5 dB. The MPV of the carotid specimens scanned at this setting correlated significantly with the histological findings (Spearman correlation, P=0.002).

CONCLUSIONS

Computer-assisted image analysis to give the MPV is a technique that may be used to identify unstable atherosclerotic plaques reliably.

Computer-aided detection and diagnosis of breast cancer

The limitations of radiologists when interpreting mammogram examinations provides a reasonable, if not compelling, basis for application of computer techniques that have the potential to improve diagnostic performance. Computer algorithms, at their present state of development, show great promise for clinical use. It can be expected that such use will only improve as computer technology and computer methods continue to become more formidable. The eventual role of computers in mammographic detection and diagnosis has not been fully defined, but their effect on practice may one day be very significant.

The role of enhanced Doppler ultrasound in differentiation of benign vs. malignant scar lesion after breast surgery for malignancy

AIM

To evaluate the benefit of echo-contrast-enhanced Doppler sonography in the differentiation of benign vs. malignant breast lesions after surgical removal of a malignant breast mass.

METHODS

Thirty-eight patients referred for biopsy of a palpable, suspicious scar lesion 1-15 years (mean 3.3 years) after surgery for breast cancer were examined. During baseline ultrasound examination a subjective scoring system of the vascularity, the number, the regularity of vessels' course and their Doppler parameters were assessed. After injection of an ultrasound contrast agent (Levovist) the same scoring system was applied to the parameters together with enhancement kinetics, enhancement intensity and enhancement pattern. Any increase in the scoring level of two or more characteristics (vascularity, number of vessels, intensity of enhancement in the tumor or regularity score of vessels in the lesion) was defined as suspicious for malignancy. A marked increase of enhancement in the immediate tumor periphery was also regarded as suspicious for malignancy. The sonographic results were assessed prospectively and correlated with the histology of the lesion.

RESULTS

Of the 38 patients with a clinically-suspicious scar lesion, there were 28 true scars and 10 malignant scar lesions. All scar lesions showed no or slight vascularity on baseline sonography. After Echocontrast-enhancement a significant increase in tumor vascularity and the number of tumor vessels could be demonstrated in all 10 malignant lesions but in only one of the 28 benign scars.

CONCLUSION

Scars pose inherent technical problems for optimal mammography. Sonographic evaluation of the vascularity of the lesion with contrast enhancing agents showed improved diagnostic accuracy in the hands of an experienced examiner.

Prognostic assessment of sonography and tumor volumetry in advanced cancer of the head and neck by use of doppler ultrasonography

OBJECTIVE

The objective of this trial was to examine the degree of tumor vascularity in lymph node metastases as depicted by computer-assisted color Doppler sonography and the tumor volumes associated with prognosis in carcinomas of the oropharynx and hypopharynx after primary radiochemotherapy.

PATIENTS AND METHODS

In a prospective trial, 25 patients with advanced squamous cell carcinomas of the oropharynx and hypopharynx (stage IV UICC 1997) were treated with radiochemotherapy. The color Doppler findings were quantified with a computer-assisted protocol that quantitatively describes color Doppler images by the relative color pixel density (CPD). As important prognostic cofactor, total tumor volume (TTV) was calculated from CT sections and related to the degree of vascularity.

RESULTS

Low CPD in neck metastases showed a correlation with better overall survival. A high-CPD group and a high-TTV group (median survival 10.1 months) were determined and were compared with all other CPD/TTV combinations (median survival 28.4 months); the difference in survival was significant (P = 0.002).

CONCLUSION

The results indicate that high tumor vascularity in combination with high TTV indicates a particularly bad prognosis in patients treated with primary radiochemotherapy for head and neck cancer.

Computerized analysis of lesions in US images of the breast

RATIONALE AND OBJECTIVES

Breast sonography is not routinely used to distinguish benign from malignant solid masses because of considerable overlap in their sonographic appearances. The purpose of this study was to investigate the computerized analyses of breast lesions in ultrasonographic (US) images in order to ultimately aid in the task of discriminating between malignant and benign lesions.

MATERIALS AND METHODS

Features related to lesion margin, shape, homogeneity (texture), and posterior acoustic attenuation pattern in US images of the breast were extracted and calculated. The study database contained 184 digitized US images from 58 patients with 78 lesions. Benign lesions were confirmed at biopsy or cyst aspiration or with image interpretation alone; malignant lesions were confirmed at biopsy. Performance of the various individual features and output from linear discriminant analysis in distinguishing benign from malignant lesions was studied by using receiver operating characteristic (ROC) analysis.

RESULTS

At ROC analysis, the feature characterizing the margin yielded Az values (area under the ROC curve) of 0.85 and 0.75 in distinguishing between benign and malignant lesions for the entire database and for an "equivocal" database, respectively. The equivocal database contained lesions that had been proved to be benign or malignant at cyst aspiration or biopsy. Linear discriminant analysis round-robin runs yielded Az values of 0.94 and 0.87 in distinguishing benign from malignant lesions for the entire database and for the equivocal database, respectively.

CONCLUSION

Computerized analysis of US images has the potential to increase the specificity of breast sonography.

Association of endometrial blood flow as determined by a modified colour Doppler technique with subsequent outcome of in-vitro fertilization

An endometrial thickness of 10 mm or more has been reported to be favourable for embryo implantation. Nevertheless, many women participating in in-vitro fertilization (IVF) programmes have adequate endometrial thickness but do not achieve satisfactory implantation. With the aid of power Doppler sonography, we examined the association between intra-endometrial vascularity and reproductive outcome. For this study, we enrolled only women with endometrial thickness >/=ISOdia>/=10 mm and excluded those with apparent endometrial pathologies. Of 95 women undergoing IVF cycles, there resulted 37 intrauterine pregnancies. The women were of similar age, body mass index, peak oestradiol concentration and endometrial thickness, and a similar number of embryos were transferred. Those women with an intra-endometrial power Doppler area (EPDA) <5 mm2 achieved a significantly lower pregnancy rate (23. 5 versus 47.5%, P = 0.021) and implantation rate (8.1 versus 20.2%, P = 0.003) than those with an EPDA >/=ISOdia>/=5 mm2. We conclude that, in addition to endometrial thickness, EPDA may serve as a factor indicative of endometrial receptivity. Women with adequate endometrial thickness but a small EPDA tended to have an unfavourable reproductive outcome.

Estimation of blood perfusion using ultrasound

Ways to measure blood perfusion using ultrasound techniques such as continuous-wave Doppler, pulsed Doppler, colour Doppler and power Doppler will be reviewed. From a certain standpoint, blood perfusion may be defined as the difference between arterial inflow and arterial outflow from a considered volume, i.e. capillary flow. The low velocities and small blood volumes involved make the signal-to-noise ratio, dynamic range and frequency resolution critical factors in the detection system. Another limiting factor is tissue motion which obscures the blood signal. Perfusion may still under certain conditions be estimated with the first moment of the Doppler power spectrum, as obtained with any Doppler ultrasound method. Modern flow mapping techniques also make it possible to estimate perfusion by counting the number of pixels that indicate flow, but low flow velocities cannot be included in the estimate. Future high-frequency systems may, however, provide very detailed images of minute flow distributions in superficial layers. Contrast agents are widely used today to enhance the blood signal, and a technique named harmonic imaging can suppress movement artefacts from surrounding tissue. Transient signals from disrupting contrast agent particles in an ultrasound field can potentially be used for perfusion quantification. Future developments to extract the blood flow signal from its noisy environment, aside from contrast agents, may be multiple sample volumes, frequency compounding and/or improved signal processing. The lack of an adequate perfusion phantom for verification of measurements of microcirculatory flow becomes, however, more apparent with improved detectability of slow flows.

Sensitivity of color Doppler sonography: an experimental approach

The purpose of this study was to estimate the size required for small vessels to become detectable with color Doppler sonography. A murine experimental tumor was examined with color Doppler sonography after injection of 1.5 mL of the contrast medium Levovist. Histologically, we measured vessel diameters inside the tumor, as well as in its direct neighborhood. With color Doppler at a transmit frequency of 7 MHz, vessels were only detected in the tumor's environment, but not inside. By histology, the 95% quantile of the vessel diameter distribution was found to be 21 microm inside the tumor, 37 microm in the underlying muscle, and 73 microm in the directly adjacent connective tissue. Vessels in the upper range of the size distribution in the muscle and connective tissue are probably detectable. Using the 95% quantile as an estimate, and correcting the values for possible shrinkage, using a factor of 1.91 reported in the literature, vessels in the 74-134 microm range may be detected under the given conditions, whereas vessels measuring 38 microm or less are inaccessible to color Doppler.

D-galactose-based signal-enhanced color Doppler sonography of breast tumors and tumorlike lesions

RATIONALE AND OBJECTIVES

This study sought to evaluate prospectively the diagnostic potential of unenhanced and enhanced color Doppler and power Doppler for the differentiation of tumors and tumorlike lesions of the breast.

METHODS

Ninety-two patients with 110 tumors or tumorlike lesions of the breast were investigated by unenhanced and enhanced color and power Doppler ultrasound. The sonomorphologic aspects of vascularization were analyzed. In addition, maximal systolic frequency shift, resistance, and pulsatility indices were determined.

RESULTS

In 15 (24%) of 63 primary carcinomas, 15 (68%) of 22 fibroadenomas, and all (100%) of 14 postoperative lesions, the sonomorphologic analysis for the differential diagnosis of breast tumors was improved after contrast enhancement in color Doppler mode. In comparing unenhanced color Doppler to power Doppler, the latter was found to be slightly superior (sensitivity, 60% vs. 67%; specificity, 39% vs. 45%, respectively); after enhancement, both modes were equivalent (sensitivity, 100% vs. 100%; specificity, 95% vs. 95%, respectively). Signal enhancement resulted in a significant improvement in sensitivity and specificity (P < 0.01). Typical signs of malignancy were irregular vessel calibers, serpiginous courses, penetration of the tumor's margin, and irregular reticular vascularization. The quantitative parameters proved not to be helpful for the differential diagnosis of breast tumors.

CONCLUSIONS

By improved analysis of the vascularization pattern, d-galactose-enhanced color Doppler sonography was found to provide more reliable differential diagnostic information than unenhanced Doppler ultrasound in tumors and tumorlike lesions of the breast.

Color Doppler sonography of normal breasts: detectability of arterial blood vessels and typical flow patterns

In a prospective study, 200 healthy female breasts were examined using color Doppler sonography to study the detectability and the resistive indices (RIs) of arterial vessels. In each breast, we attempted to detect two to three vessels and recorded the frequency spectrum with RI of each vessel. Blood vessels (n = 522) could be demonstrated in 196 (98%) breasts. Continuous diastolic flow (RI < 1) was found in 520 (99.6%) vessels. The mean RI of premenopausal women was 0.64; that of postmenopausal women was 0.70. This difference is highly statistically significant (p < 0.0001), but there is a marked overlap between the RIs of both groups. The variation in RI values of all women (up to 0.45), as well as in the breasts of the same woman (up to 0.31), was considerable. We conclude that modern color Doppler devices permit the detection of blood flow in the breast with regularity. Continuous diastolic flow (RI < 1) is a typical flow pattern. The variations of RI between women, and even for the same woman, are remarkable. The mean RI of premenopausal women is lower than the value for postmenopausal women.

3-D color Doppler image quantification of breast masses

In this article, new measures obtained from color Doppler images are introduced and a pilot study is described, in which these and previously published indices are evaluated for use in future work. Twenty women with breast masses observed on mammography and going to surgical biopsy were studied. Of the masses, 11 proved to be benign and 9 were malignant. Both 3-D mean frequency shift (f-CDI) and power mode Doppler (p-CDI) imaging were performed. To identify the mass and other regions of interest, vessels were displayed as rotatable 3-D color volumes, superimposed on selectable grey-scale/color flow slices. Doppler signals were recorded in each of 6 ellipsoidal regions of interest in and around the mass and 2 in normal tissues. Seven measures were computed in each region, three from power mode, two from mean frequency and two from combinations of both. Radiologists rated the grey-scale appearances of the masses on a scale of 1 to 5 (5=most suspicious) for each of 6 conventional grey-scale criteria. Of the individual vascularity measures in individual ROIs, the log speed-weighted pixel density and log power-weighted pixel density in the lesion internal periphery showed the greatest discrimination of malignancy, although neither was statistically significant nor as good as the peak variables described below. The mean visual grey-scale rating was the best discriminator overall, but two peak vascularity measures each made promising scatterplots in conjunction with the average visual grey-scale rating. These two vascularity measures were the log peak normalized power-weighted pixel density (peak NPD) and log of peak mean Doppler frequency times the peak NPD (vM x NPD(M)). Each of these two values was the maximum in any one of the five chosen ROIs closely associated with the mass. A possible rationale for the relative success of these peak values is the blood signal's normalization and the inhomogeneity of most breast cancers and the expectation that the highest velocities (shunting) and largest collections of blood are not necessarily in the same region in and around the tumor. Peak NPD of cancers varied with age, decreasing by a factor of 45 from 33 to 77 y.

Power Doppler in breast tumours: a comparison with conventional colour Doppler imaging

OBJECTIVE

Tumour vascularity can be assessed in-vivo using Doppler ultrasound. The purpose of this study was to determine whether Power Doppler imaging (PDI) better differentiates benign from malignant breast masses than conventional colour doppler imaging (CDI) on the basis of assessment of tumour vascularity.

METHODS

One-hundred women with solid breast lumps (51 malignant lesions, 49 benign lesions) were investigated using a Toshiba SSA-270A ultrasound machine with a 5.0 MHz (3.75 MHz Doppler reference frequency) or a 7. 5 MHz (5.0 MHz Doppler reference frequency) linear array probe. The vascularity within or at the periphery of the mass was subjectively assessed from the CDI and Power Doppler images by two independent observers. It was assumed that the absence of vascularity indicated benignity and the presence of flow malignancy.

RESULTS

CDI showed sensitivities of 62 and 42% and specificities of 62 and 62% using the 5 and 7.5 MHz probes respectively. PDI showed sensitivities of 76 and 51% and specificities of 56 and 48% using the 5 and 7.5 MHz probes respectively. A comparison of images of the 59 lesions investigated with both probes on both CDI and PDI concluded that the 5 MHz (3.75 MHz DRF) probe displayed equal vascularity to the 7.5 MHz (5.0 MHz DRF) probe in 76% of cases and greater vascularity in 24% of cases on CDI, and 68 and 31% of cases respectively on PDI.

CONCLUSION

Power Doppler imaging with a 5 MHz (3.75 MHz DRF) probe increases the sensitivity of Doppler ultrasound to malignant breast tumours but the sensitivity achieved is not high enough to propose it as a screening investigation.

Use of colour and spectral Doppler ultrasound examination in gynaecology

Objective: To review and sum up the published literature on gynecological Doppler ultrasound examination. Methods: Publications on gynecological Doppler ultrasound examination already known by the author, publications found in the bibliographic database Medline, and publications found in the reference lists of available studies were read, and relevant information was extracted and summarized. Results: Reference data representative of normal findings at transvaginal color and spectral Doppler ultrasound examination of the uterine and ovarian arteries have been established in healthy pre- and post-menopausal women and in normal early pregnancies. Blood flow velocities in the uterine and ovarian arteries change during the normal menstrual cycle and are very different in pre- and post-menopausal women. Lower blood flow velocities and higher pulsatility index (PI) values have been recorded in the ovarian arteries after the menopause. Uterine artery blood flow velocities increase and uterine artery PI values and resistance index (RI) values decrease with gestational age in the first trimester. There is not yet an established role of the gynecological Doppler ultrasound examination in clinical practice. It remains unclear whether the gynecological Doppler ultrasound examination contributes substantially to the clinical management of early pregnancy complications or infertility problems, to the differential diagnosis of pelvic masses or uterine pathology. Conclusions: Large prospective studies-preferably randomized controled trials-are needed to determine the clinical value of the gynecological Doppler ultrasound examination. Copyright 1997 Elsevier Science Ireland Ltd.