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Biomedical subjects

D O Cosgrove

Publications and source records attributed to D O Cosgrove.

At least 37 records · Page 2Linked to original sources
PubMed2000

Liver lesions: intermittent second-harmonic gray-scale US can increase conspicuity with microbubble contrast material-early experience.

The authors investigated the effect of intermittent second-harmonic gray-scale (ISHGS) ultrasonography (US) with SH U 508A microbubbles on the conspicuity of focal liver lesions. Twenty-three patients were included in the study. Images were analyzed subjectively and quantitatively. Objective lesion conspicuity was increased. In 12 of the 15 patients with liver malignancy, gray-scale defects were seen in previously unsuspected areas. ISHGS US may improve the sensitivity of US for liver lesions.

Adult↗
PubMed2000

Hepatic malignancies: improved detection with pulse-inversion US in late phase of enhancement with SH U 508A-early experience.

Twenty consecutive patients with known liver malignancies underwent ultrasonography (US) in conventional B mode and in pulse-inversion mode in the late hepatic-specific parenchymal phase after intravenous administration of SH U 508A, a microbubble US contrast agent. Two experienced readers assessed subjective and objective conspicuity, number of lesions, and smallest lesion diameter in each mode. Subjective and objective conspicuity were improved with pulse-inversion mode, and smaller lesions were depicted with pulse-inversion mode than with conventional B mode, improving the detection of metastases less than 1 cm in size.

Adult↗
PubMed1999

Non-invasive diagnosis of hepatic cirrhosis by transit-time analysis of an ultrasound contrast agent.

BACKGROUND: Hepatic cirrhosis is accompanied by several haemodynamic changes including arterialisation of the liver, intrahepatic shunts, pulmonary arteriovenous shunts, and a hyperdynamic circulatory state. We postulated that the hepatic first pass of a bolus of an ultrasound contrast agent injected into a peripheral vein is accelerated in patients with cirrhosis. We investigated this first pass in patients with diffuse liver disease and in normal controls to assess whether it provides useful differential diagnostic information. METHODS: We enrolled 15 patients with biopsy-proven cirrhosis, 12 patients with biopsy-proven non-cirrhotic diffuse liver disease, and 11 normal controls. We carried out continuous spectral doppler ultrasonography of a hepatic vein from 20 s before to 3 min after a peripheral intravenous bolus injection of 2.5 g Levovist. The intensity of the doppler signal was measured and used to plot time-intensity curves. FINDINGS: Patients with cirrhosis showed a much earlier onset of enhancement (arrival time; mean 18.3 s) and peak enhancement (mean 55.5 s) than controls (49.8 s and 97.5 s) or patients with non-cirrhotic diffuse liver disease (35.8 s and 79.7 s). All patients with cirrhosis had an arrival time of the bolus of less than 24 s, whereas the arrival time was 24 s or more in 22 of the 23 other participants. Peak enhancement was higher in patients with cirrhosis (mean 48.7 units) than in the other two groups (12.5 and 12.3 units, respectively). We found highly significant differences between the patients with cirrhosis and each of the other two groups for all variables (p<0.005), whereas we found no significant differences between non-cirrhotic patients and controls. INTERPRETATION: Our preliminary study suggests that analysis of liver transit time of a bolus of ultrasound contrast agent provides useful information about haemodynamic changes in patients with cirrhosis. Measurement of the arrival time of the bolus allows discrimination of patients with cirrhosis from controls and from patients with non-cirrhotic diffuse liver disease, and has potential as a non-invasive test for cirrhosis.

Adult↗
PubMed1999

Stimulated acoustic emission to image a late liver and spleen-specific phase of Levovist in normal volunteers and patients with and without liver disease.

Quantitative studies were performed to investigate liver- specific uptake of the microbubble Levovist, using stimulated acoustic emission (SAE), which can detect microbubbles even when stationary or slow-moving. These comprised studies of biodistribution comparing the liver and kidney in five normal volunteers, reproducibility in 34 patients, comparison between cirrhotics and controls (n = 9 each) and maximal depth of effect at different frequencies (180 measurements in 31 patients). Stimulated acoustic emission lasted beyond 30 min, with strongly liver-specific properties in each volunteer and was highly reproducible. No difference in the amount of SAE in the superficial liver was seen between cirrhotic and normal livers, but attenuation was higher in cirrhotics. This demonstrates a frequency-dependent effect on liver SAE penetration. We conclude that the liver uptake of Levovist lasts over 30 min, is reproducible, occurs even where diffuse liver disease is present and can be used to assess tissue attenuation in a novel fashion.

Adult↗
PubMed1999

Improved imaging of liver metastases with stimulated acoustic emission in the late phase of enhancement with the US contrast agent SH U 508A: early experience.

PURPOSE: To see whether stimulated acoustic emission (SAE) in the liver parenchyma in the late phase of enhancement with SH U 508A increases the conspicuity of occult metastases at ultrasonography (US). MATERIALS AND METHODS: Eighteen patients with known hypo- or hypervascular hepatic metastases underwent US after SH U 508A administration, after a delay of at least 5 minutes, to ensure decay of blood pool enhancement. In 16 patients with visible metastases, conspicuity was compared on registered SAE and gray-scale scans by two blinded readers and by using computerized analysis of relative gray-scale and color Doppler conspicuity scores inside and outside the lesion. In nine patients, areas suspected of being involved but without definite gray-scale masses were imaged in the same way. Paired sections were analyzed by two blinded readers looking for parenchymal color defects without corresponding gray-scale masses; nine control images from three healthy volunteers were also included. RESULTS: Intense, transient parenchymal SAE was seen in all subjects. All metastases appeared as areas of reduced or absent signal. The conspicuity score was 80% for SAE versus 9% for gray-scale US (P < .001, Wilcoxon signed rank test). SAE-specific defects were seen in all patients but in none of the volunteers. Metastases seen on SAE but undetectable on gray-scale images were proved in three patients. CONCLUSION: SAE with SH U 508A improves the conspicuity of metastases. SAE-specific defects may reveal isoechoic or subtle metastases.

Biopsy↗
PubMed1998

Prolongation and optimization of Doppler enhancement with a microbubble US contrast agent by using continuous infusion: preliminary experience.

PURPOSE: To investigate whether continuous infusion of an echo-enhancing contrast agent for up to 15 minutes can provide uniform and prolonged enhancement. MATERIALS AND METHODS: Six volunteers each received one bolus and three infusions of a microbubble contrast agent over 6-15 minutes at (a) a standard rate (mean, 2.08 mL/min), (b) a fast rate at twice the standard rate, and (c) a slow rate at half the standard rate. Spectral Doppler intensitometry of the femoral artery was performed for all infusions. Spectral Doppler ultrasound (US) scans of the femoral artery and color Doppler US scans of the carotid artery were subjectively assessed. RESULTS: All infusions provided an equilibrium plateau of constant prolonged enhancement starting after 1-2 minutes and lasting until the end of the infusion. Enhancement at the plateau was +13 dB (slow rate), +17.1 dB (standard rate), and +18.3 dB (fast rate) compared with baseline. Saturation artifacts with infusions were markedly fewer than those with bolus injections. Dose effectiveness (duration of enhancement that measured at least 7.5 dB per gram of contrast agent) was markedly improved with the infusions, from 0.8 min/g for the bolus to 2.6 min/g for the slow infusion. CONCLUSION: Continuous infusion of the microbubble contrast agent provided prolonged and uniform enhancement of Doppler signals and improved image quality by minimizing saturation artifacts.

Adult↗
PubMed1998

Liver vascular transit time analyzed with dynamic hepatic venography with bolus injections of an US contrast agent: early experience in seven patients with metastases.

Spectral Doppler intensitometry to study transit of a bolus of an ultrasonographic (US) contrast agent in the hepatic veins was performed in seven patients suspected of having liver metastases and seven control subjects. All control subjects had a late response (rise time, > 25 seconds; time to peak intensity, > 45 seconds), whereas six of seven patients had an early response (rise time, < 25 seconds; time to peak intensity, < 45 seconds) (P < .01).

Adult↗
PubMed1997

The ureteric jet index: a novel measure of divided renal function.

The aim of this study was to evaluate an index of divided renal function based on the quantification of the ureteric jets seen on colour Doppler ultrasound of the bladder. Thirty-one patients attending for scintigraphic renography underwent colour Doppler ultrasound with video recording for 5 min. Divided renal function was calculated as the proportion of jets from the right-sided orifice ('jet index'). This was compared with the corresponding 'scintigraphic index' found using Patlak-Rutland graphical analysis. Absolute discrepancies were calculated. Twenty-eight of thirty-one (90%) of studies were diagnostic for the calculation of jet indices. The mean jet index was 52% (n=28, SEM=5.8%) compared to a mean scintigraphic index of 54% (n = 28, SEM = 4.0%). The two scores were correlated, with a correlation coefficient of 0.72 and the median absolute difference between the two scores was 7.7%. Forty-three per cent (12/28) of subjects had discrepancies in the two scores of 5% or less. The score differences, however, showed a highly skewed distribution with 32% (9/28) subjects showing discrepancies over 20%. This discordant group (> 20% difference) included three patients with functional pelviureteric obstruction, one with a pelvic mass and one with an underfilled bladder. Two patients with very poor quality jets had impaired renal function. In one case, the index improved after angioplasty for renal artery stenosis. This simple test is a useful adjunct to urinary tract ultrasound but should be interpreted alongside evidence of renal obstruction, and complements rather than replaces existing tests.

Adolescent↗
PubMed1997

Power Doppler US of the normal prepubertal testis: does it live up to its promises?

PURPOSE: To assess whether power Doppler ultrasound (US) improves the detection of flow in normal prepubertal testes. MATERIALS AND METHODS: Seventy-two normal testes of 38 prepubertal boys (age range, 2 weeks to 12.5 years) were scanned with color and power Doppler US (7-MHz transducer). The two modalities were compared subjectively to determine which one was more sensitive for detection of flow. Only reproducible intratesticular flow signals were considered positive; capsular flow was disregarded. RESULTS: Power Doppler US depicted flow in 50 testes (69%), while color Doppler US depicted flow in 47 testes (65%, not statistically significant). Power and color Doppler US combined depicted flow in 57 testes (79%), which was significant when compared with color Doppler US alone (P = .002). Detection of flow was subjectively easier with power Doppler US in 10 of 72 testes, while it was easier with color Doppler US in 14 of 72 testes. Motion artifacts were greater with power Doppler US. CONCLUSION: Power Doppler US was equally sensitive as conventional color Doppler US in the detection of flow in normal prepubertal testes. Combining both modalities improved detection of flow in 14% of cases and may be useful in excluding torsion in children. For a positive preoperative diagnosis of torsion in children, radionuclide scintigraphy remains the imaging modality of choice.

Artifacts↗
PubMed1997

Spontaneous dissections of the internal carotid artery: appearances on colour Doppler ultrasound.

Spontaneous dissection of the internal carotid artery (ICA) is an unusual finding. We present an analysis of five patients (aged 40-60 years) with ICA dissections, describing the various flow patterns detected on colour Doppler ultrasound. Particular attention was paid to the presence of a dual lumen, the direction of flow in the false lumen and the velocity/spectral broadening of the Doppler trace obtained from the true and false lumens. Four different patterns were observed. Narrowing of the true lumen by the false lumen thrombus was seen in two cases with a low velocity Doppler waveform; three cases had a patent false lumen ("double lumen" pattern); the direction of flow in the patent false lumen varied from being (i) forward, (ii) reversed and (iii) bidirectional. The flow dynamics in carotid dissections are complex and are primarily dependent upon the presence of thrombus within the false lumen, the entry and exit flaps if the false lumen is patent, the motion of the flap wall and the extent of the dissection. They illustrate the diverse nature of the disease and Doppler ultrasound plays an important role in the imaging of ICA dissections.

Adult↗
PubMed1995

Device to enhance visibility of needle or catheter tip at color Doppler US.

The authors tested a device that allows the tip of a needle to be visualized at color Doppler ultrasonography. The device directs an oscillating air column through a 0.016-inch inner-diameter hollow stylet, creating movement at only the needle tip. The movement is reliably and accurately displayed as a beacon of color at depths of 15 cm in vitro.

Catheterization↗