Effect of Levovist on splanchnic hemodynamics in cirrhotic patients

A systematic review and meta-analysis of portal vein morphometry in pediatric and adult populations: Drawing the line between normal and abnormal findings

PURPOSE

The morphometry of the hepatic portal vein is of clinical importance, particularly in pre-operative assessments, surgical management, and diagnoses of liver conditions. This systematic review and meta-analysis aimed to characterize the morphometry of the normal portal vein in both pediatric and adult patients.

METHODS

The study, conducted using the PRISMA guidelines and registered with PROSPERO, utilized the MEDLINE, EMBASE, SCOPUS and Web of Science databases up to May 2020, and updated to May 2023. All studies reporting extractable data on diameter, length, and cross-sectional area (CSA) of the main, left, and right portal veins (PV, LPV, RPV, respectively) were included. The AQUA Tool was used to assess the quality of the included studies. Data analysis included subgroup analyses based on geographical location, sex, age, and imaging modality.

RESULTS

A total of 122 studies with 11,637 subjects were eligible for inclusion. Overall, the pooled mean diameter of the PV (PVD) was 10.09 mm (95% CI: 9.56-10.62). Significant differences in diameter were found between pediatric (6.60 mm; 95% CI: 5.38-7.82) and adult (10.72 mm; 95% CI: 10.25-11.19) subjects. Additionally, there was a significantly larger PVD measurement from computed tomography (CT) than other imaging modalities: CT, 13.28 mm (95% CI: 11.71-14.84); magnetic resonance imaging (MRI), 10.50 mm (95% CI: 9.35-11.66) and ultrasound (US), 9.81 mm (95% CI: 9.47-10.16). The mean diameters of the LPV and RPV were 8.27 mm (95% CI: 6.78-9.77) and 8.33 mm (95% CI: 6.70-9.95), respectively. Mean PV length in adults is 48.63 mm (95% CI: 35.63-61.64). Mean CSA of the PV was 1.09 cm2.

CONCLUSIONS

The study obtained aim to improve the understanding of portal vein anatomy, especially with relevance to surgical interventions of the liver in both pediatric and adult patients. Measurements from ultrasound imaging closely approximates the generated pooled PVD mean for pediatric and adult patients. CT imaging, however, significantly exceeded the established 13 mm threshold for adults. For pediatric patients, a threshold of 8 mm is proposed as a diagnostic upper limit for a normal PVD. Although not significant, the PVD decreased from the portal confluence towards its bifurcation.

Potential stagnation in the splanchnic hemodynamics demonstrated by the dynamic microbubbles in chronic liver disease

BACKGROUND AND AIM

Impaired splanchnic hemodynamics are well-documented phenomena in cirrhosis. However, comprehensive hemodynamic features from the superior mesenteric artery (SMA) to the superior mesenteric vein (SMV) via intestinal capillaries have not been studied. The aim was to examine splanchnic hemodynamics and their relationship with clinical presentations.

METHODS

Contrast-enhanced ultrasound was performed for both the SMA and SMV under fasting conditions and postprandially following ingestion of a liquid diet. The microbubble traveling time (MTT) was determined as the difference between the contrast onset in the SMA and SMV, indicating the time required for microbubble transit through the splanchnic circulation.

RESULTS

There were 192 subjects for fasting conditions (81 cirrhosis, 72 chronic hepatitis, 39 healthy controls), and 74/192 for postprandial conditions (44 cirrhosis, 11 chronic hepatitis, 19 healthy controls). The MTT (fasting; postprandial) was significantly longer in cirrhosis (7.7 ± 2.9 s; 7.0 ± 0.3 s) than in controls (5.4 ± 2.3 s, P < 0.001; 3.9 ± 0.9 s, P<0.001) and chronic hepatitis (6.3 ± 2.5 s, P=0.007; 5.1 ± 1.4 s, P=0.013). The MTT ratio (postprandial/fasting) showed disease-related changes: 0.75 ± 0.20 in controls, 0.78 ± 0.15 in chronic hepatitis, and 1.00 ± 0.28 in cirrhosis (P=0.003, vs controls; P=0.036, vs chronic hepatitis).

CONCLUSIONS

The real-time observation of traveling microbubble on the sonogram revealed a prolonged transit with a weak postprandial response in the intestinal circulation, suggesting better understanding of underlying pathophysiology of splanchnic hemodynamics in chronic liver disease.

Advances in ultrasonic diagnosis of hepatic fibrosis and early cirrhosis

With the development of medical ultrasonic technology, sonography has become an important means for diagnosis and evaluation of hepatic fibrosis and early cirrhosis. Two-dimensional sonography is the basic means of ultrasonic diagnosis and can be used to display the appearance and echo of the liver. Color Doppler sonography and Doppler frequency spectrum permit assessment of the portal venous system and detection of portal blood flow. They can be used not only for estimation of hepatic parenchymal changes but also for evaluation of portal hypertension and its complications. Contrast-enhanced ultrasound permits use of a blood-pool tracer and can assess the blood flow perfusion of hepatic parenchyma. Elasticity imaging indirectly reflects tissue pathological changes by measuring tissue elastic modulus. Fibroscan has shown great promise for staging and diagnosing hepatic fibrosis and monitoring the development of hepatic cirrhosis and portal hypertension, thus offering a new method for noninvasive diagnosis of hepatic diseases. The clinical application of these techniques has greatly improved the diagnosis of hepatic diseases. In this article, we will review the recent advances in ultrasonic diagnosis of hepatic fibrosis and early cirrhosis.

Diagnosis of liver cirrhosis with contrast-enhanced ultrasound

The assessment of the extent of liver fibrosis is very important for the prognosis and clinical management of chronic liver diseases. Although liver biopsy is the gold standard for the assessment of liver fibrosis, new non-invasive diagnostic methods are urgently needed in clinical work due to certain limitations and complications of biopsy. Noninvasive imaging studies play an important role in the diagnosis of focal liver disease and diffuse liver diseases. Among them, ultrasonography is the first choice for study of the liver in clinical work. With the development of ultrasound contrast agents and contrast specific imaging techniques, contrast-enhanced ultrasound (CEUS) shows good performance and great potential in the evaluation of liver fibrosis. Researchers have tried different kinds of contrast agent and imaging method, such as arrival time of contrast agent in the hepatic vein, and quantitative analysis of the enhancement level of liver parenchyma, to evaluate the degree of liver fibrosis during the past 10 years. This review mainly summarizes the clinical studies concerning the assessment of liver fibrosis using CEUS.