Double contrast-enhanced MRI of viral hepatitis-induced cirrhosis: correlation of gross morphological signs with hepatic fibrosis

Noninvasive staging of liver fibrosis: review of current quantitative CT and MRI-based techniques

Liver fibrosis features excessive protein accumulation in the liver interstitial space resulting from repeated tissue injury due to chronic liver disease. Liver fibrosis eventually proceeds to cirrhosis and associated complications. So, early diagnosis and staging of liver fibrosis are of vital importance for clinical treatment. Liver biopsy remains the gold standard for the diagnosing and staging of fibrosis, but it is suboptimal due to various limitations. Recently, efforts have been made to migrate toward noninvasive techniques for assessing liver fibrosis. CT is relatively easy to perform, relatively standardized for different scanners, and does not require additional hardware in liver fibrosis staging. MRI is frequently performed to characterize indeterminate liver lesions. Because it does not use ionizing radiation and features high image contrast, its role has increased in the staging of liver fibrosis. More recently, several studies on liver fibrosis staging using deep learning algorithms in CT or MRI have been proposed and have shown meaningful results. In this review, we summarize the basic concept, diagnostic performance, and advantages and limitations of each technique to noninvasively stage liver fibrosis.

Gallbladder fossa volume decreased in livers without gallbladders: A cadaveric study

The gallbladder normally lies within a fossa on the visceral surface of the liver. The primary purpose of this study was to determine whether the volume of this fossa was reduced after cholecystectomy. Livers were obtained from embalmed cadavers of 19 females and 15 males with a mean age of 84.1 ± 10.8 yrs. The presence of a gallbladder was assessed, the volume of the irregularly-shaped gallbladder fossa determined from a mold of the fossa, and the dimensions of each fossa were estimated. The mean volume of gallbladder fossae from livers with gallbladders (n = 26; 13 females and 13 males) was 31.01 ± 17.82 ml, which was significantly greater than fossae in livers without gallbladders (n = 8, 6 females, 2 males) which was 8.75 ± 4.72 ml (P<0.0001). This difference still was significant after correcting fossa volume for overall liver weight and length of the femur. Livers with gallbladders had significantly larger dimensions (depth, length, and width) of their fossae molds than did livers without gallbladders (P<0.05). The largest percentage difference between the two groups in these dimensions was in the fossae depth, and there was a significant, positive correlation between all three of these dimensions and the overall volume of the fossae. Even looking only at female livers which tend to be smaller, gallbladder fossa volume was reduced in livers without a gallbladder. Thus, the present study demonstrated that the mean gallbladder fossa volume was significantly decreased in livers lacking gallbladders, even after correcting for the liver weight and size of the individual. While the mechanisms behind these changes in fossa volume currently are unknown, alterations in mechanical pressure relayed to adjacent liver cells after gallbladder removal may play a role in these fossa volume differences.

Sclerotic changes of cavernous hemangioma in the cirrhotic liver: long-term follow-up using dynamic contrast-enhanced computed tomography

PURPOSE

To determine the intra- and extralesional factors that predict sclerotic degeneration of hepatic hemangiomas in the cirrhotic liver on long-term follow-up computed tomography (CT) examinations.

MATERIALS AND METHODS

Fifty-seven hepatic hemangiomas (> 5 mm in diameter) in 41 cirrhotic patients, recruited over a 5-year period (January 2005-December 2009), were subjected to CT to determine which factors predict sclerotic contraction or degeneration in hemangiomas. Prior and follow-up CT examinations (from 2000 to 2018) were included to observe time-related changes. The patients' gender, age, cause of cirrhosis, progression of background liver cirrhosis, lesion size/location/contrast enhancement pattern, and serum aspartate transaminase to platelet ratio index were correlated with sclerotic changes of each lesion.

RESULTS

According to the dynamic CT features, 36 of 57 (63%) hemangiomas were determined to have sclerotic changes during the follow-up period (1.1-14.4 years, median: 7.8 years), including 28 lesions (49%) reduced by ≥ 20% in diameter. In univariate analysis, age (p = 0.047) and morphological progression of background cirrhosis (p = 0.013) were significantly related to sclerotic change of hemangiomas. In the logistic regression analysis, only morphological progression of background liver cirrhosis independently predicted sclerotic change (odds ratio: 4.88, p = 0.007). With the exception of exophytic location free from size reduction (p = 0.023 in multivariate analysis), no other analyzed factors were significantly correlated with sclerotic changes.

CONCLUSION

Overall, sclerotic changes of hepatic cavernous hemangioma followed the morphological progression of background liver cirrhosis, while exophytic lesions tended to be free of size reduction.

'Hepato-diaphragmatic fat interposition' and 'increased right hemi-diaphragmatic thickness': new imaging signs for early diagnosis of hepatic cirrhosis on routine CT abdomen

BACKGROUND

Cirrhosis of liver is often a silent disease and need early diagnosis for effective treatment strategy.

OBJECTIVES

The present article aims to describe new imaging signs for early diagnosis of cirrhosis on routine CT. These are 'hepato-diaphragmatic fat interposition' (HDFI) and 'increased right hemi-diaphragmatic thickness' (increased r-DT sign).

MATERIALS AND METHODS

This was a retrospective study based on the presence or absence of cirrhosis of liver (n = 100). 'HDFI sign' was labeled as positive if F is more than 50% of D; where F is the medio-lateral extent of the intra-abdominal fat along the postero-medial margin of liver and D is the distance from the lateral vertebral margin to the medial margin of the outer-most rib in the same axial image. Increased 'r-DT sign' is labeled when the dimension on right side exceeds left side by at least 0.2 cm. Pearson χ² was performed to calculate the p value. A p value of < 0.05 was considered to indicate a significant difference.

RESULTS

There was a significant difference between cirrhotic and normal group, The sensitivity, specificity, positive predictive value and the negative predictive value of HDFI sign was found to be 94%, 62%, 71.21% and 91.17%, while that of increased r-DT sign was found to be 96%,52%, 66.66% and 92.85%. The area under the ROC curve for the HDFI sign was found to be 0.78 as compared to 0.74 for the increased r-DT sign.

CONCLUSION

Both these new signs should be used as additional imaging signs for early diagnosis of cirrhosis.

Clinical and Preclinical Imaging of Hepatosplenic Schistosomiasis

Schistosomiasis, a neglected tropical disease, is a major cause of chronic morbidity and disability, and premature death. The hepatosplenic form of schistosomiasis is characterized by hepatosplenomegaly, liver fibrosis, portal hypertension, and esophageal varices, whose rupture may cause bleeding and death. We review currently available abdominal imaging modalities and describe their basic principles, strengths, weaknesses, and usefulness in the assessment of hepatosplenic schistosomiasis (HSS). Advanced imaging methods are presented that could be of interest for hepatosplenic schistosomiasis evaluation by yielding morphological, functional, and molecular parameters of disease progression. We also provide a comprehensive view of preclinical imaging studies and current research objectives such as parasite visualization in hosts, follow-up of the host's immune response, and development of noninvasive quantitative methods for liver fibrosis assessment.

Multidetector Computed Tomography for Retrospective, Noninvasive Staging of Liver Fibrosis

Although not traditionally used to assess hepatic fibrosis, computed tomography (CT) is fast, accessible, robust, and commonly used for abdominal indications. CT metrics are often easily retrospectively obtained without special equipment. Metrics such as liver segmental volume ratio, which quantifies regional hepatic volume changes; splenic volume; and liver surface nodularity scoring show diagnostic performance comparable to elastography techniques for detecting significant and advanced fibrosis. Other emerging CT tools, such as CT texture analysis and fractional extracellular volume, have also shown promise in identifying fibrosis and warrant further study.

Evaluation of hepatic fibrosis: a review from the society of abdominal radiology disease focus panel

Hepatic fibrosis is potentially reversible; however early diagnosis is necessary for treatment in order to halt progression to cirrhosis and development of complications including portal hypertension and hepatocellular carcinoma. Morphologic signs of cirrhosis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) alone are unreliable and are seen with more advanced disease. Newer imaging techniques to diagnose liver fibrosis are reliable and accurate, and include magnetic resonance elastography and US elastography (one-dimensional transient elastography and point shear wave elastography or acoustic radiation force impulse imaging). Research is ongoing with multiple other techniques for the noninvasive diagnosis of hepatic fibrosis, including MRI with diffusion-weighted imaging, hepatobiliary contrast enhancement, and perfusion; CT using perfusion, fractional extracellular space techniques, and dual-energy, contrast-enhanced US, texture analysis in multiple modalities, quantitative mapping, and direct molecular imaging probes. Efforts to advance the noninvasive imaging assessment of hepatic fibrosis will facilitate earlier diagnosis and improve patient monitoring with the goal of preventing the progression to cirrhosis and its complications.

Four-dimensional flow magnetic resonance imaging in cirrhosis

Since its introduction in the 1970’s, magnetic resonance imaging (MRI) has become a standard imaging modality. With its broad and standardized application, it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging. In addition to sonography and computer tomography, MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases, for determining disease severity, and for assessing therapeutic success. MRI techniques have improved over the last few decades, revealing not just morphologic information, but functional information about perfusion, diffusion and hemodynamics as well. Four-dimensional (4D) flow MRI, a time-resolved phase contrast-MRI with three-dimensional (3D) anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body. The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest. Over the last few years, 4D flow MRI has been increasingly performed in the abdominal region. By applying different acceleration techniques, taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min. These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system. The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition, data analysis, visualization and quantification. Furthermore, in this article we highlight its development, focussing on the clinical application of the technique.

Iron-based superparamagnetic nanoparticle contrast agents for MRI of infection and inflammation

OBJECTIVE. In this article, we summarize the progress to date on the use of superparamagnetic iron oxide nanoparticles (SPIONs) as contrast agents for MRI of inflammatory processes. CONCLUSION. Phagocytosis by macrophages of injected SPIONs results in a prolonged shortening of both T2 and T2* leading to hypointensity of macrophage-infiltrated tissues in contrast-enhanced MR images. SPIONs as contrast agents are therefore useful for the in vivo MRI detection of macrophage infiltration, and there is substantial research and clinical interest in the use of SPION-based contrast agents for MRI of infection and inflammation. This technique has been used to identify active infection in patients with septic arthritis and osteomyelitis; importantly, the MRI signal intensity of the tissue has been found to return to its unenhanced value on successful treatment of the infection. In SPION contrast-enhanced MRI of vascular inflammation, animal studies have shown decreased macrophage uptake in atherosclerotic plaques after treatment with statin drugs. Human studies have shown that both coronary and carotid plaques that take up SPIONs are more prone to rupture and that abdominal aneurysms with increased SPION uptake are more likely to grow. Studies of patients with multiple sclerosis suggest that MRI using SPIONs may have increased sensitivity over gadolinium for plaque detection. Finally, SPIONs have enabled the tracking and imaging of transplanted stem cells in a recipient host.

Invasive and non-invasive diagnosis of cirrhosis and portal hypertension

With advances in the management and treatment of advanced liver disease, including the use of antiviral therapy, a simple, one stage description for advanced fibrotic liver disease has become inadequate. Although refining the diagnosis of cirrhosis to reflect disease heterogeneity is essential, current diagnostic tests have not kept pace with the progression of this new paradigm. Liver biopsy and hepatic venous pressure gradient measurement are the gold standards for the estimation of hepatic fibrosis and portal hypertension (PHT), respectively, and they have diagnostic and prognostic value. However, they are invasive and, as such, cannot be used repeatedly in clinical practice. The ideal noninvasive test should be safe, easy to perform, inexpensive, reproducible as well as to give numerical and accurate results in real time. It should be predictive of long term outcomes related with fibrosis and PHT to allow prognostic stratification. Recently, many types of noninvasive alternative tests have been developed and are under investigation. In particular, imaging and ultrasound based tests, such as transient elastography, have shown promising results. Although most of these noninvasive tests effectively identify severe fibrosis and PHT, the methods available for diagnosing moderate disease status are still insufficient, and further investigation is essential to predict outcomes and individualize therapy in this field.

Segmental difference of the hepatic fibrosis from chronic viral hepatitis due to hepatitis B versus C virus infection: comparison using dual contrast material-enhanced MRI

OBJECTIVE

We wanted to identify the geographic differences in hepatic fibrosis and their associations with the atrophy-hypertrophy complex in patients with chronic viral hepatitis using the dual-contrast material-enhanced MRI (DC-MRI) with gadopentetate dimeglumine and ferucarbotran.

MATERIALS AND METHODS

Patients with chronic C (n = 22) and B-viral hepatitis (n = 35) were enrolled for determining the subjective grade of fibrosis (the extent and thickness of fibrotic reticulations) in the right lobe (RL), the caudate lobe (CL), the medial segment (MS) and the lateral segment (LS) of the liver, with using a 5-grade scale, on the gradient echo T2(*)-weighted images of DC-MRI. The fibrosis grades of different segments were compared using the Kruskal-Wallis test followed by post-hoc analysis to establish the segment-by-segment differences. The incidences of two pre-established morphologic signs of cirrhosis were also compared with each other between the two groups of patients.

RESULTS

There were significant intersegmental differences in fibrosis grades of the C-viral group (p = 0.005), and the CL showed lower fibrosis grades as compared with the grades of the RL and MS, whereas all lobes were similarly affected in the B-viral group (p = 0.221). The presence of a right posterior hepatic notch was significantly higher in the patients with intersegmental differences of fibrosis between the RL and the CL (19 out of 25, 76%) than those without such differences (6 out of 32, 19%) (p < 0.001). An expanded gallbladder fossa showed no significant relationship (p = 0.327) with the segmental difference of the fibrosis grades between the LS and the MS.

CONCLUSION

The relative lack of fibrosis in the CL with more advanced fibrosis in the RL can be a distinguishing feature to differentiate chronic C-viral hepatitis from chronic B-viral hepatitis and this is closely related to the presence of a right posterior hepatic notch.