Liver microbubble transit time compared with histology and Child-Pugh score in diffuse liver disease: a cross sectional study

BACKGROUND

A previous pilot study showed that early arrival time of a microbubble in a hepatic vein is a sensitive indicator of cirrhosis.

AIM

To see if this index can also grade diffuse liver disease.

PATIENTS

Thirty nine fasted patients with histologically characterised disease were studied prospectively. Nine patients had no evidence of liver fibrosis, 10 had fibrosis without cirrhosis, and 20 had cirrhosis (five Child's A, seven Child's B, and eight Child's C).

METHODS

Bolus injections of a microbubble (Levovist; Schering, Berlin) were given intravenously, followed by a saline flush. Time intensity curves of hepatic vein and carotid artery spectral Doppler signals were analysed. Hepatic vein transit time (HVTT) was calculated as the time after injection at which a sustained signal increase >10% of baseline was seen. Carotid delay time (CDT) was calculated as the difference between carotid and hepatic vein enhancement.

RESULTS

Diagnostic studies were achieved in 38/39 subjects. Both HVTT and CDT became consistently shorter with worsening disease, as follows (means (SD)): HVTT: no fibrosis 44 (25) s, fibrosis 26 (8) s, Child's A 21 (1) s, Child's B 16 (3) s, and Child's C 16 (2) s; CDT: no fibrosis 31 (29) s, fibrosis 14 (6) s, Child's A 8 (1) s, Child's B 4 (4) s, and Child's C 3 (3) s. These differences were highly significant (p<0.001, ANOVA comparison). A HVTT <24 s and a CDT <10 s were 100% sensitive for cirrhosis (20/20 and 18/18, respectively) but not completely specific: 2/8 subjects with fibrosis had CDT values <10 s and 3/9 had HVTT <24 s.

CONCLUSION

This minimally invasive test shows promise not only in diagnosing cirrhosis but also in assessing disease severity.

[Comparison of bolus and infusion of the ultrasound contrast media levovist for color doppler ultrasound of renal arteries]

PURPOSE

To investigate if the duration of Doppler enhancement of the ultrasound contrast agent Levovist can be prolonged by continuous infusion compared to bolus injections in patients.

METHODS

12 patients with suspected renal artery stenosis were included. Each patient received 1 or 2 bolus injections of 4 g each and a "fast" infusion of 3 ml/min (average dose: 7 g) of Levovist. In 8 patients an additional "slow" infusion of 1 ml/min (average dose 4.2 g) was given. The duration of "strong" Doppler signal enhancement and the visualization of vessels were compared.

RESULTS

The duration of strong enhancement was substantially prolonged by the slow infusion (bolus 6:21 min, fast infusion: 8:57 min, slow infusion: 15:12 min, p < 0.001). The dose effectiveness (duration of strong enhancement per 1 g Levovist) was markedly improved from 0:57 min (bolus) to 3:36 min (slow infusion). Visualisation of the renal arteries was more complete with the slow infusion.

CONCLUSION

Levovist infusions at 1 ml/min are superior to bolus injections in the assessment of renal arteries. They prolong the enhancement, make more efficient use of a given dose of contrast material and thus allow additional clinically relevant information to be obtained at reduced cost.

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.

[Color doppler ultrasonography in peripheral artery occlusive disease: continuous application of a signal enhancer]

PURPOSE

The effect of continuous infusion of a signal enhancer on the diagnostic efficacy of Doppler ultrasound in peripheral artery disease was evaluated.

METHODS

35 patients with peripheral artery disease were investigated by Doppler ultrasound before and during infusion of a signal enhancer (Levovist). Femoral and popliteal arteries were examined. Angiographic diagnoses included occlusions (24) and stenoses (22). They were compared to plain and enhanced Doppler findings. Artefacts and effects on signal intensity were evaluated.

RESULTS

An increased Doppler signal was observed starting 1 min 35 s (mean) after begin of the infusion. It persisted for 11 min 46 s (mean). Signal enhanced studies provided less over- (0/1) and underestimation (3/5) of the findings and evaluation in the adductor channel was less compromised. Signal enhanced studies highlighted collaterals.

CONCLUSION

Doppler ultrasound in patients with peripheral arterial disease is improved by continuous application of a signal enhancer.

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.