Contrast-enhanced Power Doppler Imaging Research Articles

Static and Dynamic Cumulative Maximum Intensity Display Mode for Subharmonic Breast Imaging

The purpose of this study was to test the efficacy of static and dynamic cumulative maximum intensity (CMI) subharmonic imaging (SHI) in breast ultrasound studies. Contrast-enhanced SHI was performed in 14 women using a modified LOGIQ 9 scanner (GE Healthcare, Milwaukee, WI) transmitting/receiving at 4.4/2.2 MHz. Following mammography, baseline scans of gray scale ultrasound and power Doppler imaging (PDI) were performed. Contrast-enhanced PDI and gray scale SHI were performed after contrast agent administration. Static CMI-SHI is a composite image summarizing blood flow over multiple frames using the maximum intensity projection technique. The dynamic CMI-SHI mode depicts the gradual inflow pattern of the contrast agent in blood vessels. Both CMI-SHI modes were set up using a new automated sum-absolute-difference-based block-matching algorithm to reduce noise and blurring and compensate for motion artifacts. Evaluation of the imaging modes for detecting breast cancer was done by an experienced radiologist, blinded to histopathologic findings. Sensitivity, specificity, and receiver operating characteristic (ROC) analyses were computed and compared for all ultrasound imaging modes and mammography. Results Of the 16 lesions, 4 were malignant. The area under the ROC curve (A(z)) for the diagnosis of breast cancer was 0.64 for gray scale and PDI, 0.67 for contrast-enhanced PDI, 0.76 for mammography, 0.78 for SHI, and 0.75 for static CMI-SHI. For the dynamic CMI-SHI mode, the A(z) increased to 0.90, and this was significantly better than mammography (P = .03). The new dynamic CMI-SHI mode produced the highest A(z) for the diagnosis of breast cancer compared to conventional techniques and thus appears to improve diagnosis of breast cancer relative to conventional techniques, albeit based on a limited patient population.

The prognostic value of angiogenic activity evaluation with contrast enhanced power doppler imaging in axillary-node-negative breast carcinoma

To determine the value of contrast ultrasound on evaluating tumor angiogenic activity and its prognostic value in axillary-node-negative breast carcinoma (ANNBC). Power doppler imaging (PDI) was used to observe intratumoral vascularization before and post contrast agents injection. Intratumoral blood flow signals were measured and intratumoral vessel positive total areas (VPTA) were analyzed with computer-assisted quantitative assessment. Sections of malignant tumors were analyzed for the intratumoral microvessel density (MVD) by immunohistochemistry using monoclonal antibody to factor VIII-related antigen. The relationships within VPTA, MVD and prognosis were the main outcome measures. There was no significant correlation between VPTA and MVD before contrast agents used while there was a positive correlation between them after that. However, VPTA and MVD had significant correlation with histology grade and tumor recurrence and metastasis while had no correlation with the general clinic pathologic factors. VPTA and MVD were significantly higher in postoperative cases with recurrence or metastasis than those in cases with tumor-free. Total survival rate and tumor-free survival rate of high-VPTA or high-MVD group were significantly lower than those of low-VPTA or low-MVD group. The value of VPTA by contrast enhanced PDI was a beneficial prognostic indicator. High VPTA in ANNBC patients may has worse prognosis and antiangiogenic therapy is strongly suggested on them.

Contrast Enhanced Ultrasound for Radio Frequency Ablation of Canine Prostates: Initial Results

We determined the feasibility of contrast enhanced ultrasound for radio frequency ablation of the entire prostate as a method of minimally invasive treatment for prostate cancer in a canine model. Approval of the Institutional Animal Use and Care committee was obtained. Initially 5 dogs (group 1) were tested using variable power (5 to 30 W), time (4 to 12 minutes), bolus (0.01 to 0.04 ml/kg) and infusion (3 to 11 ml per minute at 0.015 microl/kg) injections of an ultrasound contrast agent with conventional grayscale power Doppler and pulse inversion harmonic imaging to establish optimal parameters. Subsequently 4 dogs (group 2) underwent entire prostate ablation using parameters based on group 1. The size of the thermal lesions and residual viable tissue was measured with ImageJ software (National Institutes of Health, Bethesda, Maryland) on ultrasound and pathological study. Linear regression and Student's t test were used for statistical analysis. A bolus of 0.04 ml/kg, an infusion of 11 ml per minute at 0.015 microl/kg and the contrast enhanced pulse inversion harmonic imaging mode were ranked best for guiding ablation. Thermal lesion volume was proportional to ablation power and time. There was no significant difference in measured thermal lesion size in group 1 between ultrasound and pathological findings (mean +/- SD 1.51 +/- 0.74 and 1.46 +/- 0.74 cm3, p = 0.56) or in residual viable tissue in group 2 (0.43 +/- 0.043 and 0.41 +/- 0.291 cm3, p = 0.21). The average volume of prostate ablation achieved in group 2 was 96.3%. Contrast enhanced pulse inversion harmonic imaging is able to guide, monitor and control radio frequency ablation of the entire prostate.

Detection of tumor vascularity in hepatocellular carcinoma with contrast-enhanced Dynamic Flow imaging: Comparison with contrast-enhanced power Doppler imaging.

To compare the effectiveness of contrast-enhanced Dynamic Flow imaging and contrast-enhanced power Doppler imaging using Levovist(®) as a microbubble contrast agent in evaluating intratumoral vascularity in hepatocellular carcinoma (HCC). Twenty-nine patients with 54 hepatocellular carcinoma nodules (before treatment, 31; after treatment, 23) were studied with both Dynamic Flow and power Doppler imaging with intravenous injection of Levovist(®). Tumor vascularity was categorized as 0, no blood flow signals within the tumor; 1, dotlike blood flow signals within the tumor; 2, moderate blood flow signals within the tumor; and 3, abundant blood flow signals within the tumor. Detectability of intratumoral vascularity of hepatocellular carcinoma in three groups based on tumor depth, blooming and noise artifacts on contrast-enhanced Dynamic Flow and contrast-enhanced power Doppler imaging were also compared with results obtained using dynamic CT as a the gold standard. The effectiveness of contrast-enhanced Dynamic Flow and contrast-enhanced power Doppler imaging in assessing therapeutic effect were compared at the same time. The ability of contrast-enhanced Dynamic Flow Doppler imaging to detect tumor vascularity in the superficial and intermediate hepatocellular carcinoma groups was close to that of contrast-enhanced power Doppler imaging (p>0.05). However, contrast-enhanced Dynamic Flow imaging demonstrated tumor parenchymal stain in 28 hepatocellular carcinoma nodules (61%), which was not detected by contrast-enhanced power Doppler imaging. Further, significantly fewer artifacts appeared in contrast-enhanced Dynamic Flow imaging than in contrast-enhanced power Doppler imaging (p<0.001). In assessing therapeutic response, the sensitivity of contrast-enhanced Dynamic Flow imaging was similar to that of dynamic CT. In deep areas, however, those more than 6 cm below the surface of the body, contrast-enhanced Dynamic Flow imaging was less sensitivity than contrast-enhanced power Doppler imaging (p=0.005). Contrast-enhanced Dynamic Flow imaging provides an effective approach to assessing intratumoral vascularity and therapeutic response in HCC lesions situated less than 6 cm from the surface of the body. It is superior to contrast-enhanced power Doppler imaging in its ability to detect tumor parenchymal stain and production of fewer artifacts.

Multigated contrast-enhanced power Doppler to measure blood flow in mice tumors.

This study evaluated an image-gating method using contrast-enhanced power Doppler ultrasound (US) to estimate blood perfusion in mice tumors. A mathematical model that compensates for the effect of bubble destruction by US pulses was used to determine contrast flow through an image plane. Multigated power Doppler images were obtained following contrast injection. Contrast flow index (CFI) was determined by measuring the area under the color level vs. time curve for each gating frequency. CFI was compared with true flow. The method was first evaluated using a flow phantom with variable flow rates, and then verified in a mouse model with implanted tumors. Color levels in Doppler images were modulated with gating frequency due to variable destruction of microbubbles by US pulses. CFI measured from the images correlated strongly with true flow in the flow phantom (r(2) = 0.87). The proposed method yielded reproducible CFI for mice tumors, suggesting that multigated contrast-enhanced power Doppler imaging may provide noninvasive measurement of tumor perfusion in mice.

Assessment of image quality of contrast-enhanced power doppler imaging in hepatocellular carcinoma with the personal ultrasound imager: Comparison with the conventional machine

To evaluate the usefulness of contrast-enhanced power Doppler imaging with the personal ultrasound imager in depicting intratumoral vascularity in hepatocellular carcinoma. Contrast-enhanced power Doppler imaging was used to examine 52 hepatocellular carcinoma nodules in 29 patients, using both the personal ultrasound imager and the conventional ultrasound machine in combination with intravenous injection of Levovist(®). Results obtained using dynamic CT were used as the gold standard. The ability of the personal ultrasound imager to detect intratumoral vascularity was compared with that of the conventional ultrasound machine, and the usefulness of the personal ultrasound imager in assessing therapeutic effect after nonsurgical treatment was compared with that of dynamic CT at the same time. The personal ultrasound imager and the conventional ultrasound machine, using the fundamental power Doppler imaging mode (p=0.13) and contrast-enhanced power Doppler imaging mode (p=0.41), did not differ significantly in depicting the vascularity of the 52 hepatocellular carcinomas. The sensitivity, specificity, and accuracy of contrast-enhanced power Doppler imaging on the personal ultrasound imager were 95.5%, 87.5%, and 94.2%, respectively, in close agreement with results obtained using dynamic CT. After the 22 hepatocellular carcinomas were treated, the personal ultrasound imager provided diagnostic accuracy of 90.9% on residual tumors when compared with results obtained by dynamic CT, and results obtained using the conventional ultrasound machine were similar. The highly portable personal ultrasound imager using Levovist(®)-enhanced power Doppler imaging can clearly depict the intratumoral vascularity of hepatocellular carcinoma nodules before and after treatment, achieving results very close to those obtained using the conventional diagnostic ultrasound machine. The personal ultrasound imager is an alternative to the conventional ultrasound machine for depicting tumor vascularity.

The influence of changing blood flow during the heart cycle of three-dimensional contrast enhanced power doppler imaging

The influence of changing blood flow during the heart cycle of three-dimensional contrast enhanced power doppler imaging

Contrast-Enhanced Power Doppler Imaging: Comparison With Scintigraphic Phases of Revascularization of the Femoral Head in Legg-Calvé-Perthes Disease

The authors evaluated the usefulness of an ultrasound contrast agent (SHU 508A) to help identify different scintigraphic phases of revascularization of the femoral head in children with Legg-Calvé-Perthes (LCP) disease. Eighteen unenhanced and contrast-enhanced power Doppler images and scintigrams of the pathologic hip in 18 children with LCP disease were compared. The scintigraphic stages of Conway's classification for LCP disease (stage A, recanalization; stage B, neovascularization) were compared with the degree of vascularity and mean peak enhancement ratios obtained from analysis of Doppler sonograms. Qualitatively, the patient's age (< or = or >7 years old) at the time of examination had a significant effect on the degree of vascularity visualized on postcontrast ultrasound images according to the scintigraphic stages. Quantitatively, there were no differences for overall mean peak enhancement ratios between stages A and B. Power Doppler ultrasound increased visualization of Doppler signals significantly but did not help in differentiating scintigraphic phases.

New developments in ovarian cancer screening

ABSTRACTDuring the last decade, a great interest in developing an effective strategy for ovarian cancer screening has been observed. Two distinct strategies have emerged: the first based on transvaginal ultrasound, and the second called multimodal screening. This review addresses most of the papers published on this topic in the last 5 years and summarizes recent developments in sections on the screening tests, target populations and newly published trials. The advantages of three-dimensional power Doppler imaging in the accurate detection and assessment of ovarian tumor angiogenesis are presented. The possible positive impact of three-dimensional (3D) ultrasound, 3D power Doppler and contrast-enhanced 3D power Doppler imaging on early detection of ovarian cancer and the accuracy of the ultrasound screening strategy are also discussed. Its role as a secondary screening tool is currently under evaluation at our Department in Zagreb.

Contrast-enhanced power Doppler imaging of normal and decreased blood flow in canine prostates

The purpose of this study was to investigate if Sonazoid™, a new ultrasound (US) contrast agent, can improve the delineation of areas with normal and decreased blood flow in the prostate. Sonazoid™ was administered in the dose range of 0.00625–0.0375 μL microbubbles/kg into five anaesthetised mongrel adult male dogs. Transrectal power Doppler imaging of the prostate was performed in 2-D and 3-D with a C9-5 end-fire probe, using an HDI 3000 scanner. An area of decreased blood flow was created by inducing tissue ablation with a CL60 laser system, to mimic an avascular lesion. A subjective assessment of the intraprostatic vessels and the prostate vascular architecture was performed, with and without Sonazoid™, before and after inducing the abnormal site. Visibility of the prostate blood flow improved following Sonazoid™ injection ( p < 0.001). A symmetric, radial vascular pattern was identified in the normal prostate prior to tissue ablation, but only on the enhanced images. After tissue ablation, a disturbance of the normal vascular pattern and identification of areas with lack of blood flow was possible, following Sonazoid™ injection. Furthermore, the location and size of these areas were verified in all dogs by gross histology examination. Sonazoid™ enhances the visibility of the prostate vascular architecture and improves, thereby the delineation of areas with normal and decreased blood flow. (E-mail: else.krueger.hagen@no.nycomed-amersham.com)

Tumor vascularization in experimental melanomas: correlation between unenhanced and contrast enhanced power doppler imaging and histological grading

The purpose of this study was to evaluate the reliability of unenhanced and enhanced power Doppler sonography in visualization of intratumoral angioneogenesis. Thirty-seven malignant melanomas, which had been implanted intra- or subcutaneously in 22 mice, were examined. Various B-mode criteria, power Doppler criteria and spectral Doppler parameters were evaluated before and after IV-application of the d-galactose-based contrast agent Levovist. After sonographic examination, all tumors were analyzed histologically with semiquantitative grading of tumoral vascularization. Unenhanced, in 70% of the tumors, no intratumoral vessels were visible using power Doppler, but only in 11% of the intracutaneous and in 0% of the subcutaneous after injection of the contrast agent. The enhanced mode was definitely superior to unenhanced Doppler in showing the intratumoral vascularity. The intratumoral vascular structure could be sufficiently analyzed in 30% of all tumors by unenhanced Doppler, but in 92% enhanced. The mean percentage vessel area increased about 433% after application of Levovist (intracutaneous: 485%, subcutaneous: 280%). Despite the missing direct correlation between the sonographically and histologically determined grade of tumor vascularization (Pearson’s correlation unenhanced 0,356, p < .05/enhanced 0.395, p < .05), the correlation between the percentage vessel area and the histologic grade of vascularization was improved after application of the contrast agent (Pearson’s correlation unenhanced 0.347, p < .05/enhanced 0.686, p < .01). We did not find a significant direct correlation between histologically and sonographically determined degree of vascularization. However, the correlation was improved using a d-galactose-based signal-enhancing agent in power Doppler sonography. (E-mail: ralf.schroeder@charite.de)

Evaluation of change in blood flow by contrast-enhanced power Doppler imaging during norepinephrine-induced renal vasoconstriction.

We evaluated the changes in flow induced by intrarenal infusion of norepinephrine by an ultrasonographic contrast agent and power Doppler imaging. Hypoperfusion was induced in dogs (N = 5) by infusing norepinephrine directly into the renal artery for 30 min at doses of 0.7 microg/kg/min, 1.0 microg/kg/min, and 1.9 microg/kg/min. Contrast agent injections were made before and after each infusion of norepinephrine. The transit of contrast agent through the kidney and color enhancement were measured by computer analysis of power Doppler images. Mean transit time and effective renal plasma flow were measured. The effective renal plasma flow decreased by 29%, 30%, and 64%, respectively, with the increasing doses of norepinephrine. Paralleling this change, the mean transit time, which corresponds to reduction in renal blood flow, increased by 26%, 43%, and 77%, respectively, from the preinfusion value. Regression analysis shows renal blood flow to decrease exponentially with norepinephrine dose. Renal blood flow changes measured by contrast-enhanced imaging correlated closely with the effective renal plasma flow measurements. Computer analysis of contrast-enhanced power Doppler images allowed measurement of renal blood flow. This technique may be useful in assessing renal perfusion during pharmacologic and other therapeutic interventional procedures.