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At least 541 records · Page 30Linked to original sources
PubMed2005

1.5 Harmonic Imaging Sonography with microbubble contrast agent improves characterization of hepatocellular carcinoma.

AIM: To investigate the usefulness of 1.5 Harmonic Imaging Sonography with the use of the contrast agent Levovist for the diagnosis of hepatocellular carcinoma (HCC) and for the evaluation of therapeutic response. METHODS: Phantom experiments were performed to compare the contrast effects of 2(nd) harmonic imaging and 1.5 Harmonic Imaging Sonography. 1.5 Harmonic Imaging Sonography was employed to examine 36 patients with HCC (42 nodules) before and after the treatment and to compare against the findings obtained using other diagnostic imaging modalities. RESULTS: In 1.5 Harmonic Imaging Sonography, the tumor vessels of HCCs were clearly identified during the early phase, and late-phase images clearly demonstrated the differences in contrast enhancement between the tumor and surrounding hepatic parenchyma. Blood flow within the tumor was detected in 36 nodules (85.7%) during the early phase and in all 42 nodules (100%) during the late phase using 1.5 Harmonic Imaging Sonography, in 38 nodules (90.5%) using contrast-enhanced CT, in 34 nodules (81.0%) using digital subtraction angiography (DSA), and in 42 nodules (100%) using US CO(2) angiography. Following transcatheter arterial embolization, 1.5 Harmonic Imaging Sonography detected blood flow and contrast enhancement within the tumors that were judged to contain viable tissue in 20 of 42 nodules (47.6%). However, 6 of these 10 cases were not judged in contrast-enhanced CT. 1.5 Harmonic Imaging Sonography was compared with the US CO(2) angiography findings as the gold standard, and the sensitivity and specificity of these images for discerning viable and nonviable HCC after transcatheter arterial embolization were 100% and 100%, respectively. CONCLUSION: 1.5 Harmonic Imaging Sonography permits the vascular structures of HCCs to be identified and blood flow within the tumor to be clearly demonstrated. Furthermore, 1.5 Harmonic Imaging Sonography is potentially useful for evaluating the therapeutic effects of transcatheter arterial embolization on HCC.

Adult↗
PubMed2006

In vivo perfusion estimation using subharmonic contrast microbubble signals.

OBJECTIVE: The purpose of this study was to quantify perfusion in vivo using contrast-enhanced subharmonic imaging (SHI). METHODS: A modified LOGIQ 9 scanner (GE Healthcare, Milwaukee, WI) operating in gray scale SHI mode was used to measure SHI time-intensity curves in vivo. Four dogs received intravenous contrast bolus injections (dose, 0.1 mL/kg), and renal SHI was performed. After 3 contrast agent injections, a microvascular staining technique based on stable (nonradioactive) isotope-labeled microspheres (BioPhysics Assay Laboratory Inc, Worcester, MA) was used to quantify the degree of perfusion in 8 sections of each kidney. Low perfusion states were induced by ligating surgically exposed segmental renal arteries followed by contrast agent injections and microvascular staining. Digital clips were transferred to a personal computer, and SHI time-intensity curves were acquired in each section using Image-Pro Plus software (Media Cybernetics, Silver Spring, MD). Subharmonic fractional blood volumes were calculated, and the perfusion was estimated from the initial slope of the fractional blood volume uptake averaged over 3 injections. Subharmonic perfusion data were compared with the gold standard (ie, the microspheres) using linear regression analysis. RESULTS: In vivo gray scale SHI clearly showed flow and, thus, perfusion in the kidneys with almost complete suppression of tissue signals. In total, 270 SHI time-intensity curves were acquired, which reduced to 94 perfusion estimates after averaging. Subharmonic perfusion estimates correlated significantly with microsphere results (r = 0.57; P < .0001). The best SHI perfusion estimates occurred for high perfusion states in the anterior of the kidneys (r = 0.73; P = .0001). The corresponding root mean square error was 2.4%. CONCLUSIONS: Subharmonic perfusion estimates have been obtained in vivo. The perfusion estimates were in reasonable to good agreement with a microvascular staining technique.

Albumins↗
PubMed2006

Corona enhancement in ultrasonographical post-vascular phase images with microbubble contrast agent: a novel specific sign for hepatocellular carcinomas.

In 1.5 Harmonic Imaging ultrasonography (1.5 HI US), images are obtained in a band intermediate between the fundamental and 2nd harmonic components, resulting in stronger contrast enhancement than in conventional harmonic imaging. We attempted to assess the hemodynamics of hepatocellular carcinomas (HCC) with special attention to blood drainage using 1.5 HI US. Forty-two HCC nodules, metastatic liver tumors and hepatic hemangiomas were studied. In contrast studies, intermittent ultrasound transmission was performed for a period of up to 45 sec after the injection of contrast agent, which was regarded as the vascular phase. The time point of 5 min later was specified as the post-vascular phase, and images were obtained by single manual transmission for comparison of contrast enhancement with surrounding hepatic parenchyma. In addition, histological examination was performed. 1.5 HI US clearly demonstrated the strong tumor vessels in most HCCs. Corona enhancement, in which the areas surrounding the tumor are enhanced, was observed in 71.4% (30/42) of HCC nodules during the post-vascular phase. This sign was not observed in any other tumors. Histological findings revealed that CD34-positive-endothelial cells were prominent in the surrounding area of HCC. In conclusion, 1.5 HI US is an effective tool for evaluating hemodynamics in both early- and post-vascular phase. Corona enhancement may be due to the trapping of contrast agent in the endothelial cells in the surround of HCC nodules and be a novel specific sign for HCC.

Adult↗
PubMed2006

Microbubble contrast for radiological imaging: 2. Applications.

Conventional Doppler provides information on blood flow including both flow and direction and flow velocity. Information on the slowly flowing blood at the capillary level, however, has not previously been available on state of the art Doppler. Contrast enhanced ultrasound provides, for the first time, information on tissue perfusion such that CEUS may now play a role in liver mass characterization and the evaluation of masses in other solid viscera similar to the role of contrast enhanced CT and MR scan. Renal applications include similar mass characterization and evaluation of renal perfusion and the renal vasculature. Surveillance of aortic stent grafts, monitoring RFA, and evaluation of both prostate and breast masses are further areas of interest. Our experience with ultrasound contrast expands progressively, and essentially adds vascular information to any region when blood flow information is required. The addition of CEUS to clinical practice has significant impact on patient management. In patients with an incidental liver mass on sonography, for example, characterization at the time of tis detection reduces the time to diagnosis and decreases referrals to CT or MR scan. Ultrasound contrast agents are easy to use, have a very low incidence of adverse events, and are unaffected by renal function. As they add no radiation for their use, they are highly appropriate in pediatric and young adult patients. Ultrasound is enhanced by addition of contrast agents.

Contrast Media↗
PubMed2006

Benign liver masses: imaging with microbubble contrast agents.

Benign focal liver lesions are frequently encountered in routine ultrasound (US) scanning as well as in staging US examination for the patients with known malignancy. Noninvasive characterization of benign liver masses by imaging features has been a challenge for the radiologist. Some benign liver masses show typical findings on US; however, these findings are not highly specific. Contrast-enhanced ultrasound (CEUS) is useful to make an instant, confident diagnosis of benign liver masses. Contrast-enhanced multiphasic computed tomography (CT) is an excellent imaging technique to detect and characterize focal liver masses. But there are a considerable number of indeterminate focal liver lesions, which require further evaluation. CEUS provides the evaluation of perfusion and hemodynamics of nodular liver lesions as well as real-time morphologic evaluation of lesion vascularity. Most benign liver masses show characteristic features on CEUS, allowing an accurate diagnosis. This review article describes typical enhancement features of common benign liver masses.

Adenoma↗
PubMed1997

Transrectal ultrasound microbubble contrast angiography of the prostate.

BACKGROUND: Prostate cancer, suspected by serum prostate-specific antigen (PSA) elevation and/or digital abnormalities, is not always evident on gray-scale or color Doppler transrectal ultrasound (TRUS). EchoGen (Sonus Pharmaceuticals, Inc., Bothell, WA), a blood vessel image enhancer able to visualize smaller, low-flow vessels and thus possibly the microvascular angiogenesis often associated with cancer, was employed to see if it would improve prostate cancer detection, particularly in patients with a rising serum PSA and prior negative biopsies. METHODS: Color Doppler TRUS was performed before and after intravenous injection of 0.05 ml/kg of EchoGen. Random and/or specifically directed sextant TRUS biopsies were performed. RESULTS: Fifteen patients with serum PSA elevations were included in the study. Fourteen had a negative prior biopsy (1-3 x). Prostate cancer was detected in 5 patients. Microvascular patterns were judged abnormal in 8 patients, 2 of which proved malignant, 2 of which were benign, and 1 of which was diagnosed with prostatis. False-negative results were observed in 3 patients, whose positive biopsy sites were from the prostate apex. CONCLUSIONS: Following EchoGen administration, prostate blood vessel image enhancement was noted in all patients, and there were no adverse reactions during or after EchoGen administration with the dose employed.

Aged↗
PubMed1987

Effect of intracoronary injections of sonicated microbubbles on left ventricular contractility.

Despite the recent interest in contrast-enhanced echocardiography as a means of defining myocardial perfusion, the effects of echo contrast agents on left ventricular (LV) contractility in humans remains poorly defined. This is particularly relevant because intracoronary injection of contrast agents used for angiographic visualization of coronary arteries produces significant alterations in LV hemodynamics. The relation of LV end-systolic wall stress (sigma es) to rate-corrected velocity of fiber shortening (Vcfc), a load-independent index of contractility, was studied in 7 patients undergoing elective coronary arteriography. Two-dimensional and targeted M-mode echocardiographic and central aortic pressure tracings were recorded during injections of standard volumes of angiographic (7 to 9 ml of nonsonicated Renografin-76) and echocardiographic (1.5 to 2.0 ml of sonicated Renografin-76) contrast agents into the left main coronary artery. The order in which agents were injected was randomly determined. Myocardial contractility was assessed under control conditions and 5 and 15 seconds after injection. Alterations in contractility relative to control were measured as the change in Vcfc after elimination of afterload (sigma es) as a confounding variable. An injection of Renografin-76 adequate for angiographic imaging of coronary artery anatomy resulted in a significant depression of LV contractility (p less than 0.001) in conjunction with a tendency toward increased afterload (p = 0.12); recovery occurred by 15 seconds after injection. The smaller amounts of sonicated Renografin-76 required to give adequate contrast enhancement of the myocardium did not alter LV contractile state or afterload.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗