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.

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.

Subharmonic-Aided Pressure Estimation for Monitoring Interstitial Fluid Pressure in Tumors: Calibration and Treatment with Paclitaxel in Breast Cancer Xenografts.

Interstitial fluid pressure (IFP) in rats with breast cancer xenografts was non-invasively estimated using subharmonic-aided pressure estimation (SHAPE) versus an invasive pressure monitor. Moreover, monitoring of IFP changes after chemotherapy was assessed. Eighty-nine rats (calibration n = 25, treatment n = 64) were injected with 5 × 106 breast cancer cells (MDA-MB-231). Radiofrequency signals were acquired (39 rats successfully imaged) with a Sonix RP scanner (BK Ultrasound, Richmond, BC, Canada) using a linear array (L9-4, transmit/receive: 8/4 MHz) after administration of Definity (Lantheus Medical Imaging, North Billerica, MA, USA; 180 µL/kg) and compared with readings from an invasive pressure monitor (Stryker, Berkshire, UK). An inverse linear relationship was established between tumor IFP and SHAPE (y = -1.06x + 28.27, r = -0.69, p = 0.01) in the calibration group. Use of this relationship in the treatment group resulted in r = 0.74 (p < 0.05) between measured (pressure monitor) and SHAPE-estimated IFP (average error: 6.24 mmHg). No significant before/after differences were observed with respect to paclitaxel treatment (5 mg/kg, Mayne Pharma, Paramus, NJ, USA) with either method (p ≥ 0.15).

Contrast-enhanced ultrasound evaluation of residual blood flow to hepatocellular carcinoma after treatment with transarterial chemoembolization using drug-eluting beads: a prospective study.

OBJECTIVES: To evaluate the accuracy and change over time of contrast-enhanced ultrasound (US) imaging for assessing residual blood flow after transarterial chemoembolization of hepatocellular carcinoma with drug-eluting beads at 2 different follow-up intervals. METHODS: Data from 16 tumors treated by transarterial chemoembolization with drug-eluting beads were successfully obtained. As part of the study, patients provided consent to undergo contrast-enhanced US examinations the morning before embolization, 1 to 2 weeks after embolization, and the morning before follow-up contrast-enhanced magnetic resonance imaging (MRI) or computed tomography (CT) (1 month after embolization). Blinded review of contrast-enhanced US and MRI/CT studies were performed by 2 radiologists who evaluated residual flow as no change, partial change, or no residual flow. Inter- and intra-reader variability rates were calculated before discordant individual reads were settled by consensus. RESULTS: The only adverse event reported during the contrast-enhanced US examinations was a single episode of transient back pain. Contrast-enhanced US at 1 to 2 weeks after embolization (n = 14) resulted in 100% sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Contrast-enhanced US 1 month after embolization (n = 15) resulted in 75% sensitivity, 100% specificity, 100% positive predictive value, 92% negative predictive value, and 93% accuracy. Inter-reader agreement was 86% for contrast-enhanced US at 1 to 2 weeks, 93% for contrast-enhanced US at 1 month, and 100% for contrast-enhanced MRI/CT at 1 month, whereas intra-reader agreement was 71% for contrast-enhanced US at 1 to 2 weeks, 87% for contrast-enhanced US at 1 month, and 91% for MRI/CT. CONCLUSIONS: Contrast-enhanced US imaging at 1 to 2 weeks after the procedure may be a viable alternative to MRI/CT for evaluating residual blood flow after transarterial chemoembolization with drug-eluting beads, albeit with a higher degree of reader variability.

Contrast-Enhanced Subharmonic and Harmonic Ultrasound of Renal Masses Undergoing Percutaneous Cryoablation.

RATIONALE AND OBJECTIVES: The objective of this study was to evaluate and compare contrast-enhanced subharmonic and harmonic ultrasound as tools for characterizing solid renal masses and monitoring their response to cryoablation therapy. MATERIALS AND METHODS: Sixteen patients undergoing percutaneous ablation of a renal mass provided informed consent to undergo ultrasound examinations the morning before and approximately 4 months after cryoablation. Ultrasound contrast parameters during pretreatment imaging were compared to biopsy results obtained during ablation (n = 13). Posttreatment changes were evaluated by a radiologist and compared to contrast-enhanced magnetic resonance imaging (MRI)/computed tomography (CT) follow-up. RESULTS: All masses initially showed heterogeneous enhancement with both subharmonic and harmonic ultrasound. Early contrast washout in the mass relative to the cortex was observed in 6 of 9 malignant and 0 of 4 benign lesions in subharmonic mode and 8 of 9 malignant and 1 of 4 benign lesions in harmonic imaging. In cases where the lesion was adequately visualized at follow-up (n = 12), subharmonic and harmonic ultrasound showed accuracies of 83% and 75%, respectively, in predicting treatment outcome. Although harmonic imaging showed less overall error, no significant differences (P > .29) in ablation cavity volumes were observed between MRI/CT and either contrast-imaging mode. CONCLUSIONS: Subharmonic and harmonic contrast-enhanced ultrasound may be a safe and accurate imaging alternative for characterizing renal masses and evaluating their response to cryoablation therapy. Although subharmonic imaging was more accurate in detecting effective cryoablation, harmonic imaging was superior in quantifying ablation cavity volumes.

Comparison of photoacoustically derived hemoglobin and oxygenation measurements with contrast-enhanced ultrasound estimated vascularity and immunohistochemical staining in a breast cancer model.

In this preliminary study, we compared two noninvasive techniques for imaging intratumoral physiological conditions to immunohistochemical staining in a murine breast cancer model. MDA-MB-231 tumors were implanted in the mammary pad of 11 nude rats. Ultrasound and photoacoustic (PA) scanning were performed using a Vevo 2100 scanner (Visualsonics, Toronto, Canada). Contrast-enhanced ultrasound (CEUS) was used to create maximum intensity projections as a measure of tumor vascularity. PAs were used to determine total hemoglobin signal (HbT), oxygenation levels in detected blood (SO2 Avg), and oxygenation levels over the entire tumor area (SO2 Tot). Tumors were then stained for vascular endothelial growth factor (VEGF), cyclooxygenase-2 (Cox-2), and the platelet endothelial cell adhesion molecule CD31. Correlations between findings were analyzed using Pearson's coefficient. Significant correlation was observed between CEUS-derived vascularity measurements and both PA indicators of blood volume (r = 0.49 for HbT, r = 0.50 for SO2 Tot). Cox-2 showed significant negative correlation with SO2 Avg (r = -0.49, p = 0.020) and SO2 Tot (r = -0.43, p = 0.047), while CD31 showed significant negative correlation with CEUS-derived vascularity (r = -0.47, p = 0.036). However, no significant correlation was observed between VEGF expression and any imaging modality (p > 0.08). Photoacoustically derived HbT and SO2 Tot may be a good indicator of tumor fractional vascularity. While CEUS correlates with CD31 expression, photoacoustically derived SO2 Avg appears to be a better predictor of Cox-2 expression.

Contrast-enhanced ultrasound-guided Sentinel lymph node biopsy of the ocular conjunctiva.

OBJECTIVES/HYPOTHESIS: Sentinel lymph node biopsy (SLNB) has been utilized for cutaneous melanoma and other malignancies arising from the eye and ocular adnexa. Currently, SLNB requires blue dyes and/or radiopharmaceuticals; both of which have significant shortcomings. This study sought to evaluate the feasibility of SLNB with the use of real-time, contrast-enhanced ultrasound (CEUS) as an alternative technique for tumors arising in the conjunctiva. STUDY DESIGN: Prospective feasibility study in a porcine model. METHODS: Twelve experiments were performed on six non-tumor-bearing Yorkshire swine. An ultrasound contrast agent, Sonazoid (GE Healthcare, Oslo, Norway), (99m) technetium ((99m) Tc), and methylene blue (MB) (Covidien, Mansfield, MA) were injected in the ocular conjunctiva. Sentinel lymph nodes (SLNs) were localized with CEUS and findings were compared to that of MB and (99m) Tc. Fisher exact test was used. RESULTS: Contrast-enhanced SLNs were identified within an average of 6.2 minutes from time of injection of Sonazoid. A total of 17 SLNs were identified by at least one of the three techniques. Correlation between Sonazoid and (99m) Tc was 94.1% (16/17 SLNs). Correlation between (99m) Tc and MB was 88.2% (15/17). One SLN that was positive for (99m) Tc but negative for Sonazoid and was considered to be a false positive (1/17); findings were similar for MB (1/17). Differences between the three techniques were not significant (P = .886). CONCLUSIONS: CEUS-guided injection of conjunctiva for SLNB is technically feasible and correlates well with standard detection techniques. This technique shows promise for rapid, real-time, intraoperative imaging for SLNB, using a widely available imaging modality and avoiding the need for radiopharmaceuticals. LEVEL OF EVIDENCE: NA

Contrast-enhanced sonography for detection of secondary lymph nodes in a melanoma tumor animal model.

OBJECTIVES: To investigate the use of contrast-enhanced ultrasound imaging (US) for detection of secondary lymph nodes (LNs) in a naturally occurring melanoma swine model compared to surgery and pathologic assessment. METHODS: Twenty-seven Sinclair swine were studied. The perfluorobutane microbubble contrast agent Sonazoid (GE Healthcare, Oslo, Norway) was administered (1.0 mL total dose) around the melanoma, and contrast-enhanced US was used to localize contrast-enhanced sentinel lymph nodes (SLNs). Then Sonazoid (dose, 0.25-1.0 mL) was injected into the SLNs to detect contrast-enhanced efferent lymphatic channels and secondary LNs. After peritumoral injection of blue dye, a surgeon (blinded to the contrast-enhanced US results) performed a radical LN dissection. Contrast-enhanced US was used to guide removal of any enhanced secondary LNs left after radical LN dissection. Clustered conditional logistic regression analyzed the benefit of contrast-enhanced US-directed secondary LN dissection over radical LN dissection using pathologic findings as the reference standard. RESULTS: A total of 268 secondary LNs were resected, with 59 (22%) containing metastases. Contrast-enhanced US detected 92 secondary LNs; 248 were identified by radical LN dissection; and 68 were identified by both methods. Metastases were detected in 20% (51 of 248) and 40% (37 of 92) of the secondary LNs identified by radical LN dissection and contrast-enhanced US, respectively. Thus, secondary LNs detected by contrast-enhanced US were nearly 5 times more likely to contain metastases than secondary LNs removed by radical LN dissection (odds ratio, 4.8; P < .0001). Twenty-two of the 180 secondary LNs (12%) identified only by radical LN dissection contained metastases, whereas contrast-enhanced US identified 20 secondary LNs after the surgeon completed the radical LN dissection, of which 8 (40%) contained metastases. CONCLUSIONS: Secondary LNs can be detected by using contrast-enhanced US after injection of Sonazoid into SLNs. Secondary LNs detected with contrast-enhanced US are significantly more likely to contain metastases than those removed by radical LN dissection.

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.

Adenocarcinoma of the ileocolic junction and multifocal hepatic sarcomas in an aged rhesus macaque (Macaca mulatta).

An aged male rhesus macaque in our colony had decreased appetite and a loss of interest in behavioral testing. CBC analysis revealed a regenerative, microcytic, hypochromic anemia with thrombocytosis, consistent with iron deficiency. A fecal occult blood test was positive. Ultrasound imaging revealed numerous, vascularized focal liver lesions that suggested metastases. The macaque's appetite continued to decrease, and he became more lethargic. At this point, the investigator elected to euthanize the macaque. At necropsy, the ileocolic junction was white and abnormally thickened, and the liver was pale tan with approximately 18 discrete white masses randomly scattered throughout the hepatic parenchyma. Histologically, the mass at the ileocolic junction was identified as an intestinal adenocarcinoma, whereas the liver masses were confirmed to be undifferentiated hepatic sarcomas. This case report describes a rhesus macaque that had 2 unrelated primary neoplasms. A review of the literature indicates that this rhesus macaque is the first reported to have an adenocarcinoma of the ileocolic junction and multiple hepatic sarcomas simultaneously.

Chronic liver disease: noninvasive subharmonic aided pressure estimation of hepatic venous pressure gradient.

PURPOSE: To compare subharmonic aided pressure estimation (SHAPE) with pressure catheter-based measurements in human patients with chronic liver disease undergoing transjugular liver biopsy. MATERIALS AND METHODS: This HIPAA-compliant study had U.S. Food and Drug Administration and institutional review board approval, and written informed consent was obtained from all participants. Forty-five patients completed this study between December 2010 and December 2011. A clinical ultrasonography (US) scanner was modified to obtain SHAPE data. After transjugular liver biopsy with pressure measurements as part of the standard of care, 45 patients received an infusion of a microbubble US contrast agent and saline. During infusion, SHAPE data were collected from a portal and hepatic vein and were compared with invasive measurements. Correlations between data sets were determined by using the Pearson correlation coefficient, and statistical significance between groups was determined by using the Student t test. RESULTS: The 45 study patients included 27 men and 18 women (age range, 19-71 years; average age, 55.8 years). The SHAPE gradient between the portal and hepatic veins was in good overall agreement with the hepatic venous pressure gradient (HVPG) (R = 0.82). Patients at increased risk for variceal hemorrhage (HVPG ≥ 12 mm Hg) had a significantly higher mean subharmonic gradient than patients with lower HVPGs (1.93 dB ± 0.61 [standard deviation] vs -1.47 dB ± 0.29, P < .001), with a sensitivity of 100% and a specificity of 81%, indicating that SHAPE may be a useful tool for the diagnosis of clinically important portal hypertension. CONCLUSION: Preliminary results show SHAPE to be an accurate noninvasive technique for estimating portal hypertension.

Contrast-enhanced ultrasound imaging of sentinel lymph nodes after peritumoral administration of Sonazoid in a melanoma tumor animal model.

OBJECTIVES: The purpose of this study was to compare lymphosonography (ie, contrast-enhanced ultrasound imaging [US] after interstitial injection of a US contrast agent) for the detection of sentinel lymph nodes (SLNs) in swine with naturally occurring melanoma tumors to lymphoscintigraphy using blue dye-guided surgical dissection as the reference standard. Also, we sought to determine if lymphosonography can be used to characterize SLNs. METHODS: Sixty-three swine with 104 melanomas were evaluated. Contrast-specific US was performed after peritumoral injection (1 mL dose) of Sonazoid (GE Healthcare, Oslo, Norway). Lymphoscintigraphy was performed after peritumoral injections of technetium Tc 99m sulfur colloid. Peritumoral injection of 1% Lymphazurin (Ben Venue Labs, Inc, Bedford, OH) was used to guide SLN resection. The accuracy of SLN detection with the two imaging modalities was compared using the McNemar test. The SLNs were qualitatively and quantitatively characterized as benign or malignant based on the lymphosonography results with histopathology and RNA analyses used as the reference standards. RESULTS: Blue dye-guided surgery identified 351 SLNs. Lymphosonography detected 293 SLNs and 11 false-positives, while lymphoscintigraphy detected 231 SLNs and 20 false-positives. The accuracy of SLN detection was 81.8% for lymphosonography, which was significantly higher than the 63.2% achieved with lymphoscintigraphy (P < .0001). The accuracy of lymphosonography for SLN characterization was 80%. When the size of the enhanced SLN was taken into consideration to characterize SLNs, the accuracy was 86%. CONCLUSIONS: Lymphosonography is statistically better than lymphoscintigraphy for the detection of SLNs in this animal model. The ability to use lymphosonography as a means to characterize SLNs as benign or malignant is limited.

Parametric imaging using subharmonic signals from ultrasound contrast agents in patients with breast lesions.

Parametric maps showing perfusion of contrast media can be useful tools for characterizing lesions in breast tissue. In this study we show the feasibility of parametric subharmonic imaging (SHI), which allows imaging of a vascular marker (the ultrasound contrast agent) while providing near complete tissue suppression. Digital SHI clips of 16 breast lesions from 14 women were acquired. Patients were scanned using a modified LOGIQ 9 scanner (GE Healthcare, Waukesha, WI) transmitting/receiving at 4.4/2.2 MHz. Using motion-compensated cumulative maximum intensity (CMI) sequences, parametric maps were generated for each lesion showing the time to peak (TTP), estimated perfusion (EP), and area under the time-intensity curve (AUC). Findings were grouped and compared according to biopsy results as benign lesions (n = 12, including 5 fibroadenomas and 3 cysts) and carcinomas (n = 4). For each lesion CMI, TTP, EP, and AUC parametric images were generated. No significant variations were detected with CMI (P = .80), TTP (P = .35), or AUC (P = .65). A statistically significant variation was detected for the average pixel EP (P = .002). Especially, differences were seen between carcinoma and benign lesions (mean ± SD, 0.10 ± 0.03 versus 0.05 ± 0.02 intensity units [IU]/s; P = .0014) and between carcinoma and fibroadenoma (0.10 ± 0.03 versus 0.04 ± 0.01 IU/s; P = .0044), whereas differences between carcinomas and cysts were found to be nonsignificant. In conclusion, a parametric imaging method for characterization of breast lesions using the high contrast to tissue signal provided by SHI has been developed. While the preliminary sample size was limited, results show potential for breast lesion characterization based on perfusion flow parameters.

Static and dynamic cumulative maximum intensity display mode for subharmonic breast imaging: a comparative study with mammographic and conventional ultrasound techniques.

OBJECTIVE: 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. METHODS: 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). CONCLUSIONS: 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.

Thyroid lymphosonography: a novel method for evaluating lymphatic drainage.

OBJECTIVES: We evaluated lymphosonography, or contrast-enhanced, ultrasonography (US)-guided sentinel lymph node (SLN) detection, as a technique for demonstrating the lymphatic drainage of the thyroid gland. METHODS: In this prospective animal study, four 50-kg Yorkshire swine underwent transcutaneous injection of a US contrast agent and methylene blue dye into the thyroid gland. Contrast-enhanced US was used to identify draining lymphatic channels and SLNs. Sentinel node biopsy was conducted. Subsequently, bilateral neck and upper mediastinal dissection was carried out. RESULTS: In 3 of 4 cases, a blue dye-positive and US contrast-positive SLN was identified. We identified SLNs in level IV in 2 cases. One case revealed 2 adjacent nodes in the superior mediastinum. In 1 case, a lymphatic channel was identified traveling into the mediastinum, but exposure of the SLN could not be obtained. No residual blue dye-positive or US contrast-positive nodes were identified on subsequent dissection. CONCLUSIONS: Lymphosonography of the thyroid gland in a porcine model correlates well with blue dye-guided sentinel node biopsy and is technically feasible, although in some cases access to the SLN may be difficult. This technique could potentially enable a detailed analysis of thyroidal lymphatic drainage if applied to humans.

Lymphosonographic sentinel node biopsy of the supraglottis in a swine model.

OBJECTIVE: To test the feasibility of a novel contrast-enhanced ultrasound (CEUS) technique, or lymphosonography, for sentinel node biopsy (SNB) of the supraglottis in a porcine model. STUDY DESIGN AND SETTING: In this prospective, nonrandomized animal study, blue dye and ultrasound contrast agent were injected into the supraglottis in seven 50-kg Yorkshire swine. Transcutaneous CEUS was used to identify real-time lymphatic flow of contrast through lymph channels (LC) to the sentinel lymph node (SLN). SNB was carried out, visually identifying a blue node, with the assistance of intraoperative CEUS. Bilateral modified radical neck dissections were performed to search for any residual contrast-positive or blue SLNs. RESULTS: In each case, at least one SLN was identified by preoperative CEUS. A total of 12 nodes were identified on preoperative CEUS, and 11 of 12 nodes were stained with blue dye (91.7%). No residual blue or contrast-positive nodes were identified on neck dissection. CONCLUSIONS: Lymphosonographic SNB of the supraglottis in a porcine model is technically feasible, and yields results comparable to traditional blue dye-guided techniques. No "shine-through" effect or nonsequential nodal enhancement occurred. This technique holds promise for sentinel node biopsy and allows a novel method for in vivo investigation of the lymphatic system.

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

This study was conducted to compare quantifiable measures of vascularity obtained from contrast-enhanced color flow images of breast lesions to pathologic vascularity measurements. Nineteen patients with solid breast masses received Levovist Injection (10 mL at 300 mg/mL; Berlex Laboratories, Montville, NJ, USA). Color flow images of the mass pre and post contrast were obtained using an HDI 3000 scanner (Philips Medical Systems, Bothell, WA, USA) optimized for clinical scanning on an individual basis. After surgical removal, specimens were sectioned in the same planes as the ultrasound images and stained with an endothelial cell marker (CD31). Microvessel area (MVA) and intratumoral microvessel density (MVD) were determined for vessels 10-19 microm, 20-29 microm, 30-39 microm, 40-49 microm and > or =50 microm in diameter using a microscope and image processing software. From the ultrasound images, the number of color pixels before and after contrast administration relative to the total area of the breast mass was calculated as a first-order measure of fractional tumor vascularity. Vascularity measures were compared using reverse stepwise multiple linear regression analysis. In total, 58 pathology slides (with 8,106 frames) and 185 ultrasound images were analyzed. There was a significant increase in flow visualization pre to post Levovist injection (p = 0.001), but no differences were found between the 11 benign and the eight malignant lesions (p > 0.35). Ultrasound vascularity measurements post contrast correlated significantly with pathology (0.15 < or = r2 < or = 0.46; p < 0.03). The 30-39 microm vessel range contributed most significantly to the MVD relationship (p < 0.001), whereas the MVA was mainly influenced by vessels 20-29 microm (p < 0.004). Precontrast ultrasound only correlated with pathology for relative MVA (r2 = 0.16; p = 0.01). In conclusion, contrast-enhanced color flow imaging provides a noninvasive measure of breast tumor neovascularity, corresponding mainly to vessels 20-39 microm in diameter, when used in a typical clinical setting.

Ultrasound-guided contrast-enhanced sentinel node biopsy of the head and neck in a porcine model.

OBJECTIVE: To test the feasibility of contrast-enhanced ultrasound (CEUS)-guided sentinel lymph node biopsy (SNB) of the head and neck in a porcine model. STUDY DESIGN AND SETTING: In this prospective, nonrandomized study, methylene blue and Sonazoid were injected into the lateral tongue or floor of mouth (FOM) of four swine. Real-time CEUS was used to identify contrast in the lymphatic channels flowing to the sentinel lymph node (SLN). Endoscopic or open SNB was performed. Neck dissection was then performed, and the residual nodal packet was examined for remaining contrast-enhancing or blue dye-stained nodes. RESULTS: In all eight procedures, the SLN was visualized with ultrasound and blue dye. Seven procedures identified a single SLN, and one identified two SLNs. Subsequent neck dissections revealed no other nodes containing methylene blue or contrast in the nodal specimen or operative bed. CONCLUSION/SIGNIFICANCE: CEUS-guided SNB of the head and neck in swine is feasible, with success comparable to blue dye-guided SNB. This technique may offer several advantages over traditional techniques, and warrants further study.

Breast lesions: imaging with contrast-enhanced subharmonic US--initial experience.

PURPOSE: To prospectively compare accuracy of gray-scale subharmonic imaging (SHI) with that of standard gray-scale ultrasonography (US), power Doppler US (with and without contrast material), and mammography for the diagnosis of breast cancer, with histopathologic or clinical follow-up results as the reference standard. MATERIALS AND METHODS: This HIPAA-compliant pilot study had institutional review board approval; all subjects gave written informed consent. Fourteen women (age range, 37-66 years) had 16 biopsy-proved breast lesions. In SHI, pulses are transmitted at one frequency, but only echoes at half that frequency (the subharmonic) are received. A US scanner was modified to perform gray-scale SHI (transmitting at 4.4 and receiving at 2.2 MHz). Precontrast imaging (gray-scale US and power Doppler) was followed by contrast material-enhanced power Doppler and gray-scale SHI. A reader blinded to mammographic and pathologic findings assessed diagnosis on a six-point scale. Sensitivity, specificity, accuracy, and receiver operating characteristic (ROC) curves were computed for mammography, gray-scale and power Doppler imaging (pre- and postcontrast), and SHI. RESULTS: Of the 16 lesions, four (25%) were malignant. Mammography had 100% sensitivity and 20% specificity. Sensitivity and specificity, respectively, were 50% and 92% for precontrast imaging and 75% and 75% for contrast-enhanced power Doppler. SHI had 75% sensitivity and 83% specificity. Specificity was higher for all US modes than for mammography (P<.04). There were no significant differences in specificity among US modes or in sensitivity (P>or=.50). Area under the ROC curve for the diagnosis of breast cancer was 0.64 for standard gray-scale US and power Doppler US, 0.67 for contrast-enhanced power Doppler US, 0.76 for mammography, and 0.78 for SHI (P>.20). Contrast enhancement was better with SHI than with power Doppler (100% vs 44% of lesions with good or excellent enhancement; P=.004). CONCLUSION: SHI appears to improve the diagnosis of breast cancer relative to conventional US and mammography, albeit on the basis of results in a very limited number of subjects.

Contrast enhanced ultrasound for radio frequency ablation of canine prostates: initial results.

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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%. CONCLUSIONS: Contrast enhanced pulse inversion harmonic imaging is able to guide, monitor and control radio frequency ablation of the entire prostate.