The value of hepatic diffusion-weighted MR imaging in demonstrating hepatic congestion secondary to pulmonary hypertension

The Liver in Heart Failure: From Biomarkers to Clinical Risk

Heart failure (HF) is a clinical syndrome due to heart dysfunction, but in which other organs are also involved, resulting in a complex multisystemic disease, burdened with high mortality and morbidity. This article focuses on the mutual relationship between the heart and liver in HF patients. Any cause of right heart failure can cause hepatic congestion, with important prognostic significance. We have analyzed the pathophysiology underlying this double interaction. Moreover, we have explored several biomarkers and non-invasive tests (i.e., liver stiffness measurement, LSM) potentially able to provide important support in the management of this complex disease. Cardiac biomarkers have been studied extensively in cardiology as a non-invasive diagnostic and monitoring tool for HF. However, their usefulness in assessing liver congestion in HF patients is still being researched. On the other hand, several prognostic scores based on liver biomarkers in patients with HF have been proposed in recent years, recognizing the important burden that liver involvement has in HF. We also discuss the usefulness of a liver stiffness measurement (LSM), which has been recently proposed as a reliable and non-invasive method for assessing liver congestion in HF patients, with therapeutic and prognostic intentions. Lastly, the relationship between LSM and biomarkers of liver congestion is not clearly defined; more research is necessary to establish the clinical value of biomarkers in assessing liver congestion in HF patients and their relationship with LSM.

Part 2: Disease of the Heart and Liver: A Relationship That Cuts Both Ways

Diseases known to affect both the heart and liver include a variety of infectious, autoimmune, and metabolic disorders, as well as toxins: most commonly alcohol. As damage to both the heart and liver progresses, transplantation is a reasonable therapeutic option. Heart failure patients with underlying congestive hepatopathy receiving cardiac transplant have demonstrated improved liver enzyme levels posttransplant. Patients with severe end-stage liver disease requiring a liver transplant must undergo careful preoperative evaluation as surgical stress exposes the myocardium to high levels of catecholamines. Clinicians must consider both cardiac and hepatic complications when evaluating heart failure, cirrhosis, and nonalcoholic fatty liver disease. In Part 2 of this review, we discuss new noninvasive techniques for assessing liver fibrosis in the preoperative stage. Both serum and radiologic studies, such as transient elastography, have begun to take the place of liver biopsy due to their decreased morbidity. Last, we explore the current research examining the benefit of combined heart-liver transplant, although more longitudinal outcome studies are needed.

Liver parenchymal changes and association with cardiac magnetic resonance imaging findings in repaired tetralogy of Fallot: an intravoxel incoherent motion magnetic resonance imaging study

BACKGROUND

Liver disease can develop in repaired tetralogy of Fallot (TOF) from hepatic congestion caused by volume and pressure overload of the right ventricle. Noninvasive assessment of the liver is important for diagnosing and managing children with TOF.

OBJECTIVE

To evaluate subclinical hepatic changes without liver function test abnormality in adolescents with repaired TOF using intravoxel incoherent motion (IVIM) MRI and cardiac MRI findings.

MATERIALS AND METHODS

We included 106 young adults (75 with repaired TOF and 31 healthy individuals) in the study. Liver IVIM MRI examinations were performed with 10 b values (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 s/mm²). Two observers measured IVIM MRI parameters D true, D* and f, as well as apparent diffusion coefficient (ADC) values in liver segments 5-8.

RESULTS

D* and f values were significantly lower in adolescents with TOF (P = 0.003 vs. P = 0.05, respectively). ADC values were higher in adolescents with TOF (P = 0.005). However, we found no significant difference between adolescents with and without TOF in terms of Dtrue (P = 0.53). There was a significant correlation between f value and right ventricular ejection fraction. The intraclass correlation coefficient (ICC) analysis of the two observers showed substantial-to-excellent agreement for D, f, D true and ADC (0.7, 0.8, 0.9 and 0.8, respectively).

CONCLUSION

The results of our study suggest that impaired microperfusion with increased ADC values in adolescents with repaired TOF reflect hepatic congestion rather than fibrosis. Hepatic congestion characterized by decreased ADC values can be easily differentiated before fibrotic changes occur by using IVIM MRI to assess diffusion and microcapillary perfusion separately.

Diffusion tensor imaging of the spleen in prediction and grading of esophageal varices in cirrhotic children with portal hypertension

PURPOSE

To assess diffusion tensor imaging (DTI) of spleen in prediction and grading of esophageal varices (OV) in cirrhotic children.

METHODS

This prospective study was conducted upon 30 children with cirrhotic children with OV and 10 age-gender matched controls that underwent DTI of abdomen. Mean diffusivity (MD) and fractional anisotropy (FA) of spleen were calculated and matched with the grading of OV at endoscopy and laboratory biomarkers of portal hypertension.

RESULTS

Mean ADC of spleen in patient was significantly different (p = 0.001) from that of controls by both reviewers respectively. The cutoff ADC measurement of the spleen used for prediction of OV was ≥ 0.75 and ≥ 0.76 × 10^-3mm²/s with AUC was 0.993 and 0.997 for both reviewers respectively. The FA of the spleen in patient was different (p = 0.01) from of controls of both reviewers respectively. Cutoff FA of spleen used for prediction of OV was ≤ 0.35 and ≤ 0.36 for both observers respectively. ADC and FA of spleen was correlated with platelets count (r =  - 0.713, 0.392; p = 0.001, 0.012) and prothrombin time (r = 0.518, - 0.380; p = 0.001, 0.016).

CONCLUSION

DTI metrics of spleen can predict and grade OV and correlated with laboratory biomarkers of portal hypertension.

Evaluation of liver stiffness with magnetic resonance elastography in patients with constrictive pericarditis: Preliminary findings

PURPOSE

To evaluate with magnetic resonance elastography (MRE) whether patients with constrictive pericarditis (CP) have increased hepatic stiffness. CP results in reduced pericardial compliance, ventricular interdependence, and right heart failure. Patients with untreated CP may develop liver fibrosis and ultimately cirrhosis due to chronic venous congestion. Chronic venous congestion ± fibrosis may lead to increased liver stiffness.

MATERIALS AND METHODS

Prospectively, patients with suspected CP underwent 2D transthoracic echocardiography, cardiac MRI, and liver MRE. An automated method was used to draw regions of interest (ROIs) on the stiffness maps to calculate the mean liver stiffness in kilopascals (kPa). A t-test with α = 0.05 was performed between stiffness values of patients with positive and negative CP findings based on previously published echocardiography criteria.

RESULTS

Nineteen patients met inclusion criteria with a mean ± standard deviation (SD) age of 51 ± 16 years. Nine patients (47%) had CP. Mean liver stiffness trended higher in patients with CP compared to those without CP (4.04 kPa vs. 2.46; P = 0.045). Liver stiffness correlated with MRI septal bounce (P = 0.04), inferior vena cava size (P = 0.003), echo abnormal septal motion (P = 0.04), and echo mitral inflow variation >25% (P = 0.02). Only MRI septal bounce predicted CP by echocardiography (P < 0.001).

CONCLUSION

CP was associated with increased liver stiffness. The increased stiffness is most likely secondary to chronic hepatic venous congestion and/or fibrosis. MRE may be useful for noninvasive liver stiffness assessment in CP. J. Magn. Reson. Imaging 2016;44:81-88.

Spleen magnetic resonance diffusion-weighted imaging for quantitative staging hepatic fibrosis in miniature pigs: An initial study

AIM

To determine whether spleen diffusion-weighted imaging (DWI) parameters might classify liver fibrosis stage.

METHODS

Sixteen miniature pigs were prospectively used to model liver fibrosis, and underwent spleen DWI by using b = 300, 500 and 800 s/mm(2) on 0, 5th, 9th, 16th and 21st weekend after the beginning of modeling. Signal intensity ratio of spleen to paraspinous muscles (S/M), spleen exponential apparent diffusion coefficient (eADC) and apparent diffusion coefficient (ADC) for each b-value were statistically analyzed.

RESULTS

With increasing stages of fibrosis, S/M for all b-values showed a downward trend; and spleen eADC and ADC for b = 300 s/mm(2) showed downward and upward trends, respectively (all P < 0.05). The area under the receiver-operator curve (AUC) of spleen DWI parameters was 0.777 or more by S/M for classifying each fibrosis stage, and 0.65 or more by eADC and 0.648 or more by ADC for classifying stage ≥3 or cirrhosis. Among the spleen DWI parameters, S/M for b = 300 s/mm(2) was the best parameter in classifying stage 1 or more, 2 or more and 3 or more with AUC of 0.875, 0.851 and 0.843, respectively; and spleen eADC for b = 300 s/mm(2) was best in classifying stage 4 with an AUC of 0.988.

CONCLUSION

Spleen DWI may be used to stage liver fibrosis.

Pharmacokinetics of oral treprostinil sustained release tablets during chronic administration to patients with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive vascular disease that ultimately leads to right ventricular failure and death. Treprostinil diolamine is an oral prostacyclin analogue; sustained release tablets of oral treprostinil are currently being evaluated for efficacy and safety as a potential therapy in patients with PAH. Previous attempts at developing an oral prostanoid have been limited by rapid absorption and short plasma half-life; thus, the aim of this study was to characterize the pharmacokinetic profile of treprostinil diolamine in PAH patients after chronic dosing. The study enrolled 74 PAH patients who had been taking treprostinil diolamine for a minimum of 4 weeks (range: 0.5-16 mg). We collected plasma samples over 12 hours and estimated pharmacokinetic parameters using noncompartmental methods. Seventy patients had complete data. After chronic twice-daily oral dosing of treprostinil diolamine, mean area under the curve (AUC0-12) of treprostinil increased from 5244 to 20,4086 pg·hr-·mL- and mean maximum observed plasma concentration (Cmax) increased from 1383 to 33588 pg/mL. The apparent clearance (CL/F) was similar across all doses, indicating a linear dose-exposure relationship after twice-daily dosing. We conclude that twice-daily oral treprostinil provides sustained and proportional treprostinil concentrations over a wide range of doses during chronic administration to PAH patients.

The use of DWI to assess spleen and liver quantitative ADC changes in the detection of liver fibrosis stages in chronic viral hepatitis

This study aimed to evaluate the changes in spleen and liver diffusion-weighted magnetic resonance imaging (DWI) in chronic viral hepatitis patients. The study comprised 47 patients and 30 healthy volunteers. DWIs were obtained. Apparent Diffusion Coefficient (ADC) measurements were made by transferring the images to the workstation. The measurements of value b 1000 were made from a total of five points of the liver and three points of the spleen. Liver biopsy was performed on the 47 patients. The fibrosis stages of the patients were defined according to the METAVIR scoring system. Student's t-test was used in the comparison of mean ages, liver and spleen ADC values between the patient and the control group. Kruskal-Wallis followed by Mann-Whitney U Test with Bonferroni adjustment was performed in the comparison of mean ADC values of the patients at different stages and the control group. A statistically significant difference was determined between the patient and control group in respect of liver and spleen mean ADC values (P<0.05). F3 group showed a significant difference compared to control and F1 and F4 group showed a significant difference compared to control, F1, F2 and F3 group in terms of the mean liver ADC value (P<0.01). F3 and F4 group showed a significant difference compared to control and F1 group in terms of the mean spleen ADC value (P<0.01). As a result we believe that the measurement of liver and spleen ADC values may be an indicator in the determination of the level of fibrosis.